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doi: 10.4037/ccn2011595 2011;31:30-44Crit Care Nurse Irene Grossbach, Linda Chlan and Mary Fran Tracyand Ventilator-Related ResponsesOverview of Mechanical Ventilatory Support and Management of Patient-

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patient-ventilator dyssynchrony.Responsibilities related to ventilatormanagement may vary among acutecare settings, but the nurse is usuallythe “first-line manager” challengedwith patient- and ventilator-relatedproblems. As a result, it is essentialthat nurses thoroughly understandthe basics of ventilator support,including ventilator modes, settings,and alarms. It is also important tobe skilled in promptly identifyingand managing common patient-and ventilator-related problems inorder to provide optimal patient-centered care and prevent compli-cations. Prompt recognition ofproblems and action by the nursemay resolve acute respiratory distress,dyspnea, and increased work ofbreathing and prevent adverse events.

The purpose of this article is topresent an overview of mechanicalventilation modes and the assess-ment and management of dyspneaand patient-ventilator dyssynchrony.Strategies are presented to managepatients’ responses to mechanicalventilatory support. Finally,

Irene Grossbach, RN, MSNLinda Chlan, RN, PhDMary Fran Tracy, RN, PhD, CCNS

Overview of Mechanical Ventilatory Support and Management of Patient- andVentilator-Related Responses

mon therapy in subacute and long-term care settings. The primarygoals of mechanical ventilatorysupport are to normalize arterialblood gas levels and acid-baseimbalance by providing adequateventilation and oxygenation.Mechanical ventilation can decreasethe patient’s work of breathing byunloading respiratory muscles in asynchronous manner.1 Mechanicalventilation can also maintain long-term respiratory support of patientswith chronic ventilatory problems.

Critical care nurses encounternumerous issues related to ventila-tor support, including physiologicalconditions that impede optimalventilator function, dyspnea, and

Mechanical ventila-tory support isroutinely neededfor critically illadults in inten-

sive care units and is also a com-

Nurses must be knowledgeable about the function and limitations of ventilatormodes, causes of respiratory distress and dyssynchrony with the ventilator, andappropriate management in order to provide high-quality patient-centered care.Prompt recognition of problems and action by the nurse may resolve acute respira-tory distress, dyspnea, and increased work of breathing and prevent adverse events.This article presents an overview of mechanical ventilation modes and the assess-ment and management of dyspnea and patient-ventilator dyssynchrony. Strategiesto manage patients’ responses to mechanical ventilatory support and recommenda-tions for staff education also are presented. (Critical Care Nurse. 2011;31[3]:30-45)

©2011 American Association of Critical-Care Nurses doi: 10.4037/ccn2011595

This article has been designated for CE credit.A closed-book, multiple-choice examinationfollows this article, which tests your knowl-edge of the following objectives:

1. Differentiate various (common) modes ofmechanical ventilation

2. Identify management strategies for patientresponses to mechanical ventilatory support

3. Discuss assessments and causes ofpatient-ventilator dyssynchrony

CEContinuing Education

30 CriticalCareNurse Vol 31, No. 3, JUNE 2011 www.ccnonline.org

Feature



recommendations for staff educationare presented. Only a brief review ofcommonly used ventilation modesand basic operation is provided; inter-ested readers are referred elsewherefor more in-depth information.1-10

Common Modes of Ventilatory Support

Ventilator parameters vary bymanufacturer; however, basic param-eters are present on all machines:percent oxygen, tidal volume and/or

minute ventilation, respiratory rate,inspiratory time or flow rate, andalarm limit settings. A thoroughunderstanding of common ventila-tor settings will assist nurses in opti-mizing patients’ care to meet theoverall oxygenation and ventilationgoals, maintain safe lung pressures,and provide breathing comfort(Table 1).

Mode of ventilation refers tothe method of inspiratory supportprovided by the mechanical ventila-tor. It is the specific combinationof breathing pattern and controlvariables to deliver inspiration.4

Selection of mode is based on theclinician’s familiarity and experience

Irene Grossbach has practiced as a pulmonary clinical nurse specialist for 28 years and isan adjunct assistant professor in the school of nursing at the University of Minnesota inMinneapolis.

Linda Chlan is an associate professor in the school of nursing at the University of Minnesotain Minneapolis.

Mary Fran Tracy is a critical care clinical nurse specialist at the University of MinnesotaMedical Center, Fairview in Minneapolis.

Authors

Corresponding author: Irene Grossbach, RN, MSN, 3043 East Calhoun Parkway, Minneapolis, MN 55408 (e-mail:[email protected]).

To purchase electronic or print reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA 92656.Phone, (800) 899-1712 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, [email protected].

www.ccnonline.org CriticalCareNurse Vol 31, No. 3, JUNE 2011 31

Table 1 Definitions of ventilator and patient parameters

• Fraction of inspired oxygen (FIO2): The concentration of oxygen in the inspired gas. It can be set from 0.21 (room air) to 1.0 (100%).

• Tidal volume (Vt): The volume of gas, either inhaled or exhaled, during a breath and commonly expressed in milliliters. Vt is generallyset between 8 and 12 mL/kg but may be set lower (eg, 6 mL/kg or lower) to prevent lung overdistension and injury.

• Respiratory rate (RR) or frequency: The number of breaths per minute that the ventilator delivers. RR is commonly set between 10and 20 breaths per minute. If the patient is making spontaneous breathing efforts, RR will be higher.

• Minute ventilation (VE): The average volume of gas entering, or leaving, the lungs per minute, commonly expressed in liters perminute. The product of Vt and RR = VE. Normal VE is between 5 and 10 L/min.

• Peak flow rate or peak inspiratory flow: The highest flow, or speed, that is set to deliver the Vt during inspiration, usually measured inliters per minute. When the flow rate is set higher, the speed of gas delivery is faster and inspiratory time is shorter.

• Inspiratory(I) and expiratory(E) time and I/E ratio: The speed at which the Vt is delivered. Setting a shorter inspiratory time (I) resultsin a faster inspiratory flow rate. Average adult I is 0.7 to 1.0 s; I/E ratio is usually 1:2 or 1:3.

• Peak airway pressure (Paw): Represents the total pressure that is required to deliver the Vt and depends upon various airway resistance,lung compliance, and chest wall factors. It is expressed in centimeters of water (cm H2O).

• Plateau pressure (Pplat): The pressure that is needed to distend the lung, which can be measured by applying an end-inspiratory pausesetting on the ventilator. It is expressed in centimeters of water.

• Sensitivity or trigger sensitivity: Effort, or negative pressure, required by the patient to trigger a machine breath, commonly set so thatminimal effort (-1 to -2 cm H2O) is required to trigger the breath. Some ventilators may have flow triggering, which is more sensitivethan pressure triggering if the flow setting is set correctly. A decrease in flow is sensed when the patient makes a spontaneous effortand triggers the machine to deliver the breath.

• Positive end-expiratory pressure (PEEP): The amount of positive pressure that is maintained at end-expiration. It is expressed in centimeters of water.The purpose of PEEP is to increase end-expiratory lung volume and reduce air-space closure at end-expiration.

• Continuous positive airway pressure (CPAP): Continuous pressurization of the breathing circuit when a patient breathes spontaneously.CPAP may be used as a last step in the weaning process or as a noninvasive method of providing a pneumatic splint to the upper airway in obstructive sleep apnea.3

• Mandatory breath: A breath in which the timing and/or size of the breath is controlled by the ventilator; the machine triggers and/orcycles the breath.4

• Spontaneous breath: A breath in which both the timing and size are controlled by the patient; the patient both triggers and cycles thebreath.4

• Functional residual capacity: Volume of gas present in the lungs at the end of passive expiration.



and the institutional preferences.11

Some modes guarantee a constantvolume (volume-targeted or volume-controlled) with each machine breath,whereas other modes guarantee aconstant pressure (pressure-targetedor pressure-controlled). An additionaloption on some ventilators is a dual-controlled mode that combines thefeatures of volume- and pressure- targeted ventilation to ensure a mini-mum tidal volume (Vt) or minuteventilation (V· E) while limiting pres-sure. Table 2 summarizes differencesbetween volume- and pressure- targeted ventilation.

Volume-Targeted ModesIn a volume-targeted mode, Vt is

the targeted parameter, and a fixed Vtis delivered with each breath. Volume-targeted modes are the most com-monly used modes.12 The mode maybe labeled by different names, includ-ing controlled mandatory ventilation,continuous mandatory ventilation,and assist/control mode ventilation.

In volume-targeted modes, theventilator delivers machine-guaranteed

breaths at the set respiratory rateand Vt if the patient is not makingrespiratory efforts due to sedation,paralysis, or other factors affectingdrive to breathe. For example, if theclinician sets the Vt at 600 mL andthe respiratory rate at 10 breaths perminute, the V· E delivered is 6 L/min(600 mL × 10 breaths per minute).The ventilator sensitivity dial iscommonly set so that it takes mini-mal effort (-1 to -2 cm H2O) for thepatient to trigger the machine breath.If the patient is making inspiratoryefforts, inspiration is triggered andthe machine delivers additionalmachine breaths at the set Vt. Theinspiratory flow rate, or the speedat which the breath is delivered, isfixed; therefore, it does not changeto match the patient’s respiratoryrate and breathing pattern.

Studies have shown that patients’work of breathing can be substantialin assist/control mode, occurringthroughout the inspiratory phase,especially if the patient is air hungryand the inspiratory flows providedby the ventilator are low.2 The patient

is dependent upon the clinician toreadjust the flow rate setting todecrease work of breathing. Forexample, a patient who breathesfaster requires adjustment to ahigher flow rate to match inspira-tory efforts. If the flow rate doesnot match inspiratory efforts, it iscommon for the patient to experi-ence shortness of breath, anxiety,and agitation and for various othersigns and symptoms of increasedwork of breathing to develop.Immediate adjustment to an appro-priate flow rate setting may be thekey intervention that prevents oralleviates breathing discomfort.

Pressure-Targeted ModesPressure is the ventilator’s tar-

geted parameter in pressure sup-port ventilation. Breaths in thismode are triggered by the patientand augment or support a patient’sspontaneous inspiratory effortwith a preset positive pressurelevel. Inspiration ends after deliv-ery of the set inspiratory pressure.Two pressure-targeted modes are


Table 2 Differences in parameters between volume-targeted and pressure-targeted ventilator modes

Volume-targeted modes (Examples: CMV, VCV, A/C, SIMV)

Volume constant: Guarantees volume at expense of letting airwaypressure vary

Inspiration: Terminates when preset Vt delivered

Preset Vt delivered unless a specified pressure limit is exceeded(upper airway pressure alarm is set) or patient’s cuff or ventila-tor tubing has air leaks that cause a decrease in Vt delivered

Peak airway pressure: Variable; determined by changes in airwayresistance, lung compliance, or extrapulmonary factors. The peakairway pressure increases as needed to deliver prescribed Vt

Inspiratory flow rate: Fixed; if patient inspires faster or more vig-orously, work of breathing increases; clinician needs to promptlycorrect airway resistance and/or lung compliance problems,readjust flow-rate setting higher to match inspiratory demands

Pressure-targeted modes (Examples: PSV, PCV)

Volume variable: Guarantees pressure at expense of letting Vt vary

Inspiration: Terminates when preset pressure reached

Preset pressure delivered: Volume is variable and determined byset pressure level, airway resistance, and lung compliance factors,specified time or flow cycling criteria

Peak airway pressure: Fixed; determined by set pressure level;volume delivered is variable and decreases with increased airwayresistance, decreased lung compliance, or extrapulmonary factors

Inspiratory flow rate: Variable; if patient inspires faster or morevigorously, variable flow rate may match change in inspiratorydemand or may be insufficient; clinician needs to promptly correctairway resistance and/or lung compliance problems, may needto readjust pressure support, inspiratory, expiratory time settings

Abbreviations: A/C, assist control; CMV, controlled mechanical ventilation or continuous mandatory ventilation; PSV, pressure support ventilation; PCV, pressurecontrol ventilation; SIMV, synchronized intermittent mandatory ventilation; VCV, volume controlled ventilation; Vt, tidal volume.



common: pressure support ventila-tion and pressure control mode.

Pressure Support Ventilation. Inpressure support ventilation, vol-ume is variable, rather than a fixedVt as in volume-targeted modes,and is determined by the patient’seffort or drive, preset pressure level,and various airway resistance andlung compliance factors. Flow rateis also variable, depending on thepatient’s needs and not fixed by aclinician as it is in volume-targetedmodes. The clinician does not set arespiratory rate setting, and themode does not function if the patientis apneic. Although pressure sup-port ventilation is commonly thoughtof as a weaning mode with low pres-sure support levels set to overcomeresistance in the endotracheal tubeand ventilator circuit, high pressuresupport levels may also providealmost total ventilator support.13

Pressure Control Mode. Pressurecontrol ventilation operates in amanner similar to pressure supportventilation in that it relies on a pre-set pressure to determine the vol-ume delivered and volume is variabledepending on various factors thataffect airway resistance and/or lungcompliance. However, in pressurecontrol mode, a respiratory rate isset by the clinician in order to sup-port patients with apnea or an unre-liable respiratory drive. Pressurecontrol mode may be used in patientswith acute respiratory distress syn-drome to control plateau pressuresand Vt. Patients with acute respira-tory distress syndrome have low lungcompliance; therefore, inappropri-ately high Vt and pressure settingscan overstretch and injure the lung.Current strategies in such patientsshould be focused on limiting Vt

and maximal lung stretch. An initialVt of 6 mL/kg ideal body weight is areasonable starting point and maybe decreased to maintain maximallung distending pressures less than30 to 35 cm H2O.14,15

Dual-Controlled ModesNewer ventilators offer hybrid

modes that combine features of volume-targeted and pressure-targeted ventilation in an attempt to avoid both the high peak airwaypressures of volume ventilation andthe varying tidal volumes that mayoccur with pressure ventilation.2

Volume and pressure control vari-ables adjust automatically to ensurea minimum Vt or V· E. Several manu-facturers incorporate this mode intheir ventilators, with manufacturersusing different names for the samedual-controlled modes. Examples ofthis type of mode are pressure-regulated volume control (Servo300 and Servo-I, AVEA, CareFusion,San Diego, California) and volumeventilation plus (Puritan Bennett840, Covidien Puritan Bennett,Boulder, Colorado). Pressure-targetedlogic is used when the ventilatordetermines after each breath if thepressure applied to the airway wasadequate to deliver the desired Vt. If the Vt did not meet the set tar-get, the ventilator adjusts the pres-sure applied on the next breath.With some modes, such as volume-assured pressure support ventilation(Bird 8400 Sti, CareFusion) andpressure augmentation (BEAR 1000,CareFusion), inspiratory support isprovided in the same manner as inpressure support ventilation, butthe inspiratory pressure is adjustedwithin the current breath to obtainthe assured Vt if the set Vt is not

being achieved.3,12 Although thistechnology seems promising, objec-tive evidence has not shown thatany of the alternative methods ofventilation are more successful thanconventional mechanical ventilationwith proper attention to Vt. Nofindings from randomized trialsindicate improved outcomes,including mortality.16

Other ModesSynchronized Intermittent Manda-

tory Ventilation (SIMV) Plus PressureSupport. Two modes are in opera-tion on the SIMV plus pressure sup-port mode: mandatory breaths arevolume-targeted and spontaneousbreaths are pressure-targeted. Thepatient receives a preset number ofvolume-targeted mandatory breathsat a set Vt. For example, if the SIMVrate is set at 4 breaths per minuteand the Vt at 600 mL, the patientreceives the mandatory Vt of 600mL and 4 breaths, resulting in a V· E

of 2400 mL/min (600 mL × 4 breathsper minute). Between mandatorybreaths, the patient breathes spon-taneously on pressure supportedbreaths. The ventilator recognizesspontaneous breaths and deliversmandatory breaths only betweenthe spontaneous breaths, therebypreventing competition betweenthe 2 breath types. Pressure supportis routinely provided in SIMV modeto overcome circuit and tube resist-ance, thereby preventing increasedwork of breathing on the sponta-neous breaths. If the patient is nottaking spontaneous breaths whileon a low SIMV rate, it is essential toincrease the SIMV rate or switch toa full support mode like continuousmandatory ventilation in order toachieve adequate minute ventilation.




Continuous Positive AirwayPressure (CPAP). CPAP refers todelivery of a continuous level ofpositive airway pressure main-tained throughout the respiratorycycle. The ventilator does not pro-vide breaths during CPAP; thepatient must initiate all breaths. Ifa patient is on CPAP of 5 cm H2O,5 cm of positive pressure is appliedto the airway on inspiration andexpiration. CPAP, similar to posi-tive end-expiratory pressure(PEEP), is used to restore andmaintain the amount of air left inthe lungs at end expiration, or func-tional residual capacity. The appli-cation of positive pressure to theairways during expiration maykeep alveoli open and prevent earlyclosure during expiration. Thepresence of an artificial airwayallows intrathoracic pressure todecrease to zero, which is belowthe usual level of intrathoracicpressure. PEEP/CPAP levels of 5 cm H2O are often used to provide“physiologic PEEP.”17 CPAP may beused as a last step in the process ofdiscontinuing mechanical ventila-tion. It is also used as a noninvasivemethod of providing a pneumaticsplint to the airways in patientswith obstructive sleep apnea.3,11

Opening the airways with positivepressure prevents the upper airwayfrom collapsing with each breath.

A thorough understanding ofthe ventilator being used, includ-ing delivery modes, function ofsettings, and specific patient set-tings assists in appropriatelyevaluating and managing patients’responses. This understandingcan allow nurses to more quicklytroubleshoot problems whenthey arise.

Patient- and Ventilator-Related ProblemsGeneral Considerations and Troubleshooting Interventions

Patients not tolerating mechani-cal ventilation support may beworking to breathe and appear anx-ious, restless, agitated, and in respi-ratory distress. They may try to talkand sit up to improve breathingcomfort. The ventilator may appearto be “out of sync” with breathingefforts, and ventilator alarms maysound. Usual signs and symptomsof problems may not be observed ifpatients are sedated, unconscious,paralyzed, or experiencing neuro-muscular weakness. It is essential toappropriately set and interpret ven-tilator alarms and to promptly iden-tify and correct patient- and/orventilator-related problems. Table 3provides a detailed list of physiolog-ical, psychological, and ventilatorfactors that contribute to respiratorydistress and focuses on interventionsfor optimal care of all ventilator-dependent patients.

The troubleshooting process isguided by the severity of the distressand the stability of the patient’scondition. If the patient is in severeacute respiratory distress or is hemo-dynamically unstable, the patientshould be immediately disconnectedfrom the ventilator and manuallyresuscitated with 100% oxygen. Ifthe patient quickly improves withmanual resuscitation, the likelyproblem is the ventilator settings orcircuit.12 When the patient appearsanxious or short of breath, or if ven-tilator alarms sound, it is importantto make immediate, systematicassessments. The initial focus shouldbe patient-centered and not machine-centered. It is important to avoid

the false sense of security that,because the patient is supported bythe ventilator, he/she is receivingadequate ventilation. The ventilatoralarm can be silenced for up to 2minutes, during which the nursecan perform an assessment. Thepatient should be assessed forhemodynamic stability, adequateoxygenation, excess secretions,secure tubing connections to theventilator, and other conditionssuch as anxiety or pain. Furtherassessments of the ventilator asneeded include verification thatventilator settings and ventilatorfunction are appropriate and con-fir ma tion that connections aresecure and tubings are not kinked.

Alarm silencing once or repeatedalarm silencing without evaluatingand correcting the problem maycause prolonged periods of inade-quate ventilation. Sedated or para-lyzed patients may be severelyhypoventilated and in deterioratingcondition but not exhibit signs ofrespiratory distress because of theeffects of sedative and other med-ications and conditions that bluntthe normal responses to hypoxemiaand hypercapnia. Patients may beunable to communicate distressthrough facial expressions and ges-tures. Pulse oximetry measurementsof oxygen saturation (SpO2) mayremain greater than 90%, despitesevere hypoventilation. If the patientinitially has a high SpO2 (eg, 98%),but is hypoventilated and respira-tory acidemia develops, SpO2 meas-urements will decrease but maycontinue to be 90% or greater. Staffmay be comfortable with the valueand not question why the SpO2decreased from 98% to 90%. As theSpO2 reading decreases, the FIO2





Table 3 Potential causes of anxiety and respiratory distress with suggested interventionsa

Causes/triggers

Peak airway pressure and low tidalvolume may alarm

Airway irritation causing cough,secretions, bronchospasm

Air leaks causing volume loss

Attempting to speak, inability tocommunicate wants and needs

Airway irritation and discomfortdue to tube jarring, movement,displacement

Biting down on orally placed tube,resulting in peak airway pressurealarming, decreased tidal volumedelivery

Tube or securing device causingdiscomfort, agitation, and potentialerosion from pressure on lips,cheeks, or in mouth; displacedtube

Adverse drug effects; Sleep deprivation causing agitation,

confusion, uncooperative behavior

Intensive care unit environment(noises, unfamiliar people, pro-cedures, fear of unknown, etc)

Inadequate inspiratory flow rateto meet inspiratory demandsresulting in feeling of not gettingenough air

Inappropriately set ventilatormode, alarm settings

Interventions

Correct problems causing increased airway resistance, decreased lung compliance, and pressurelimit alarming; recheck ventilator to make sure prescribed tidal volume is delivered

Notify physician of unexplained high airway pressure and to assist in evaluation including pneumo -thorax, pulmonary edema, or problems decreasing lung compliance

Manually ventilate as needed and call for assistance

Prevent unnecessary cough, irritation, shortness of breath: • Suction only as needed for secretions• Do not instill normal saline• Ensure water condensation from tubing does not drain into patient’s airway• Maintain thin secretions for better clearance by providing optimal airway humidification

Assess, correct air leaks in endotracheal tube, tracheostomy cuff, ventilator system; recheckventilator to make sure prescribed tidal volume is delivered

Implement effective communication system (see article by Grossbach et al19 in this issue of Criiti-cal Care Nurse).

Prevent tube jarring and movementGuide and support artificial airway and tubing in manner that prevents tube from pulling and

jarring during turning and movement; may disconnect, turn, reconnect airway adapter (may becontraindicated in patients in unstable condition)

Obtain necessary assistance with turning, transferring so one person can provide specific attention to prevent pulling and jarring tube

Properly support tube on ventilator arm; unclip ventilator tubing from ventilator supportarm/reattach in manner that prevents tube from being pulled or jarred and maintains optimaltube alignment and support

Stabilize artificial airway with 1 hand when reconnecting ventilator adapter or with airway suctioning

Explain why not to bite down on tube, remind as needed; may be able to place tube in edentulousarea of mouth; use tube-securing method with bite block if needed

Inspect for proper tube position; secure tube in manner that prevents skin breakdown, maximizescomfort, and avoids displacement

Reposition orally placed tube as neededMonitor for skin breakdown at endotracheal or tracheostomy tube location

Evaluate for adverse drug effects causing anxiety, agitationProvide calm, confident, reassuring approachExplain interventions, provide frequent orientation to surroundings and reassuranceMaintain consistent staffing when possible

Coordinate interventions to allow periods of uninterrupted sleep; offer noise-canceling headsets,earplugs

Implement relaxation techniques: coaching, touch, music, or other methods defined by patientAllow patients to participate in decision making as capable

Adjust flow-rate setting to meet inspiratory demandsVentilate manually as needed, compressing bag in synchrony with patient’s inspiratory efforts

Call for assistance to evaluate ventilator for appropriate mode, correct settings, and delivery ofprescribed volume

Avoid interventions that create shortness of breath (weaning when not ready, inappropriate ventilator modes, suboptimal position)

Offer fan with airflow directed toward face, which may help decrease dyspnea, assuming thatpatient and/or ventilator-related problems are corrected; position for breathing comfort

a Based on evidence from Grossbach.18



may be increased without analyzingand correcting the underlying prob-lems that are causing the oxygendesaturation, such as inadequate ven-tilation. Hypoventilation may resultin both hypoxemia and hypercapnia.The resulting severe acute respiratoryacidemia can lead to decreasedblood pressure, cardiovasculardecompensation, and cardiac arrest.

Factors Influencing Volume DeliveryTargets. The ability of the ventilatorto deliver the preset tidal volume isinfluenced by the amount of pres-sure required to deliver that vol-ume. Peak airway pressure, or forcerequired to deliver the preset Vt, isvariable and increases with increasedairway resistance, decreased lungcompliance, and factors that makeit difficult for the chest wall toexpand. Increased airway resistancedescribes mechanical factors thatnarrow the airway and impede theflow of inspired air to the lungs.Increased airway resistance can becaused by a smaller diameter endo-tracheal tube, biting on the endo-tracheal tube, obstruction withsecretions, and bronchospasm. Fasterrespiratory rates also increase resist-ance because of greater air turbulence.

Lung compliance measures theease of expansion of the lung andthorax. Decreased lung compliancerequires more pressure to delivervolume and expand the lung becauseof various conditions includingatelectasis, pulmonary edema,fibrosis, and pneumonia. Chest wallor extrapulmonary factors that con-tribute to increased peak airway pres-sure include certain positions thatmay restrict expansion of the chestwall and lung, abdominal distention,forced abdominal muscle contrac-tions, and shivering (Figure 1).20 As

airway resistance increases or lungcompliance decreases, the peakinspiratory airway pressure increasesto deliver the preset Vt. The presetVt is delivered unless the specifiedupper airway pressure alarm limit isreached. At that point, the ventila-tor stops delivery of volume.

Loss of the preset volume occursif an air leak develops in the endo-tracheal or tracheostomy tube cuffor the ventilator system. A low vol-ume alarm sounds if the Vt or V· E isless than the preset low volume limitset by the clinician. With volumelosses, it is common for patients toexhibit anxiety, restlessness,

increased work of breathing, andother signs and symptoms of acuterespiratory distress. It is essential tocorrect airway resistance and/orlung compliance problems to main-tain Vt delivery.

Factors Influencing PressureDelivery Targets. Tidal volume inpressure-controlled modes is vari-able and changes with various fac-tors that affect airway resistanceand/or lung compliance. For exam-ple, the set pressure used to provideadequate Vt and breathing comfortmay become inadequate if the patientdevelops mucous plugs or bron-chospasm, resulting in respiratory


Figure 1 Factors that increase airway resistance and decrease lung compliance. Reprinted from Grossbach20 with permission.

Factors that decrease lung compliance• Pulmonary edema

(cardiac, noncardiac)• Pneumonia• Atelectasis• Endotracheal tube

displacement• Pneumothorax

“Extrapulmonary” factors• Positions restricting

expansion• Forced abdominal

contractions on expiration• Increased abdominal

pressure against diaphragm due to ascites, gas distention

• Shivering, other muscle contractions

• Chest wall injury, malformation

Factors that increase airway resistance• Biting down on tube• Endotracheal tube obstructed,

narrowed, displaced• Cough• Secretions• Bronchospasm• Fast respiratory rate

[



distress and potential cardiopul-monary deterioration if the problemis not resolved. A sudden resolutionof the resistance or complianceproblem may increase Vt to anamount larger than desired. Clini-cians must be alert to monitoringthe patient’s Vt and properly settingVt and V· E alarm limits, and be pre-pared to make frequent ventilatoradjustments when managing apatient whose pulmonary status maychange rapidly, as in acute asthmaor pulmonary edema. Volume-targeted or dual-controlled strate-gies are favored to maintain a con-stant Vt in situations where thepatient has frequent changes in air-way resistance or pressure.12 Pressuresupport ventilation is contraindi-cated if the patient is apneic or hasan unreliable ventilatory drive dueto central nervous depression fromdrugs or other situations.18

Dyspnea. Dyspnea is describedin many ways, including feelingshort of breath, having difficult oruncomfortable breathing, feelingbreathless, running out of air, “hardto breathe,” “can’t get a deep breath,”“can’t breathe,” feel like suffocating,a heavy chest, or “chest tightness.”It is frequently described as airhunger, choking, or heavy breath-ing.21,22 In general, only patientswith chronic obstructive pul-monary disease, but not healthyindividuals, volunteered affectivewords such as “frightening,” “wor-ried,” “helpless,” “depressed,” and“awful” to describe their breathingdifficulty.22 These affective descrip-tions are intended to convey thethreat perceived by the patients totheir breathing difficulty.23,24

Various clinical conditions con-tribute to dyspnea.25,26 Common

situations or events can trigger acycle of anxiety, agitation, frustration,fear, helplessness, and dyspnea.Examples include inability to com-municate needs, unclear or inade-quate explanations from caregivers,and inappropriate ventilator modesor settings that do not match thepatient’s respiratory demands. Evensmall losses in Vt can cause signifi-cant acute respiratory distress. Bron-chospasm may worsen in patientswith chronic obstructive pulmonarydisease or asthma or in other sus-ceptible patients, which furtherincreases airway resistance, work ofbreathing, and shortness of breath.Increased work of breathing mayincrease anxiety, stress, and oxygenrequirements and may result inhypoxemia and respiratory acidemiaif the patient does not receive appro-priate intervention (Figure 2).18

Signs of respiratory distressinclude increased respiratory rate,changes in mental state, anxiety,restlessness, distressed appearance,nasal flaring, making attempts to

breathe through the mouth, diaphore-sis, sitting upright or attempting tosit up in bed, use of accessory mus-cles in the neck, and forced abdomi-nal muscle contractions duringexpiration. Blood pressure andheart rate may or may not changesignificantly, depending on thevasoactive medications the patientis receiving. Also, patients who areheavily sedated or experiencingsevere muscle weakness or non-chemical paralysis will not exhibitthe increased respiratory muscleactivity normally observed. Respira-tory distress and increased work ofbreathing may be caused by a com-bination of factors related to thepatient and factors related to theequipment: air leaks, increased air-way resistance, decreased lung com-pliance, inadequate ventilatorsettings, and anxiety or pain.

A patient-centered approach tooptimal ventilator managementshould include routine assessmentfor dyspnea27 by using an appropriateinstrument for assessing dyspnea.25


Figure 2 Anxiety–shortness of breath cycle. Reprinted from Grossbach18 with permission.

Anxiety

↑Respiratory rate

↑Oxygen, energy requirements

↑Work of breathing

↑Airway resistance

↑Muscle tension,bronchoconstriction

Inability tomeet demands

Decompensation

↓PaO2Hypoxemia↑PaCO2

Acidemia

Shortness of breath

Event



dyssynchrony, a common cause ofdyspnea and respiratory distress.

Patient-Ventilator Dyssynchrony

Patient-ventilator dyssynchronyis defined as a situation in which thepatient’s breaths fail to coincide ormatch exactly with the ventilator-assisted breaths. This commonphenomenon can affect patients’outcomes, including duration ofmechanical ventilation31-35 and hos-pital length of stay.36

Patients exhibit various signsand symptoms of respiratory distresswhen the ventilator is not appropri-ately configured to meet the patient’sinspiratory and expiratory demands.Sensations of “fighting the ventila-tor,” being out of sync, and workingto breathe are due to dyssynchronybetween the patient’s respiratoryefforts and the ventilator. A nurse’sfirst inclination may be to encouragethe patient to “calm down,” “relax,”slow your breathing,” and “breathewith the machine” rather thanadjusting the ventilator to matchthe patient’s demands, clearing theairway of secretions, or determin-ing what the patient is trying tocommunicate in efforts to meetother needs, such as pain or a strongdesire to see a family member.

Dyssynchrony often is seriousduring all 3 phases of breath delivery:the trigger phase, the flow deliveryphase, and the breath cycling offphase.31 To achieve patient-ventilatorsynchrony, the ventilator must senseand respond quickly to inspiratoryefforts, provide inspiratory flow ofoxygen gas that matches the patient’sinspiratory demands, terminate thebreath with the patient’s terminationof inspiration, and cycle to expiration

to match the patient’s exhalationphase. To optimize patients’ com-fort and reduce the work of breath-ing, it is crucial that the machinebe adjusted to meet the patient’srequirements, including appropri-ate trigger sensitivity settings, inspi-ratory flow, inspiratory time, Vt,and an exhalation phase thatmatches the patient’s expiratorypattern. The patient is dependentupon the nurse to make accurateobservations of the ventilator inter-face. Simple observations of theventilator being “in sync” with thepatient’s efforts show easy ability totrigger the ventilator breath, deliv-ery of the breath coinciding withinspiration, appropriate breath ter-mination when the patient appearsto stop inspiration, and the ventila-tor exhalation phase properly timedto coincide with when the patientappears to be exhaling. The patientappears comfortable, conveysbreathing comfort, and is able torest and sleep. Causes for and man-agement of patient-ventilator dys-synchrony are described next.

Causes of Dyssynchrony Appropriate ventilator modes

must be selected and settingsadjusted to match and be in syn-chrony with the patient’s inspira-tory efforts. Dyssynchrony may bedue to delayed or ineffective trigger-ing, auto-triggering, insufficient flowto meet the patient’s demands, dou-ble triggering, and an exhalationphase that is out of sync with thepatient’s breathing pattern (Table 4).

Delayed or Ineffective Triggering.The most common cause of dyssyn-chrony is ineffective triggering,37

which is defined as failure of thepatient’s inspiratory muscle effort


Dyspnea assessment is useful todetermine whether ventilatoradjustments and various interven-tions, such as positioning, use of afan, music, or other relaxation tech-niques, improve breathing comfort.One dyspnea evaluation protocolasked responsive patients: “Are youfeeling short of breath right now?”and, if yes, “Is your shortness ofbreath mild, moderate, or severe?”28

These 3 broad dyspnea ratings limitpatients’ responses to changes indyspnea. The 2 most commoninstruments used to measure dysp-nea in critical care are the visualanalog scale (VAS) and the Borgscale.25,29 The VAS is a 100-mm hori-zontal line with endpoints of 0 (noshortness of breath) and 100 (worstpossible shortness of breath). Thepatient rates the degree of shortnessof breath on this line. The modifiedBorg scale is a 12-item instrumentwith numbers corresponding todescriptions regarding the amountof dyspnea,14 with no dyspnea ratedas 0 and worst imaginable dyspnearated as 10. Correlations betweenthe 2 scales are strong, and validityand reliability have been deter-mined with critically ill patients.30

The use of these instruments requiresthat patients be alert and oriented.Furthermore, each instrument is 1-dimensional; only intensity or dis-tress of dyspnea is measured.25

Various physiological, psychological,and equipment factors contributeto dyspnea and acute respiratorydistress. Evidence supports bestpractice in the assessment and man-agement of critically ill patientsexperiencing dyspnea.25 The follow-ing section describes the patient-ventilator interaction, focusing onthe causes and management of



to trigger or cycle a ventilator breath.34

The patient feels short of breath andmay demonstrate

• tachypnea, • anxiety, • restlessness,• use of accessory muscles in the

neck, • tracheal tug (downward pull

of the trachea), • nasal flaring, • paradoxical movement of the

abdominal wall during inspi-ration,

• hypertension, or• hypotension and decrease in

arterial oxygen saturation. Inability to trigger a breath can

occur even though the patient is onoptimal levels of ventilation support

to maintain normal gas exchangeand can occur on either volume orpressure modes of ventilation.Patients with frequent ineffectivetriggering may receive excessive lev-els of ventilatory support becauseof ventilator adjustments made inan effort to correct the problem.38

The main problems that can causeineffective triggering are inappropri-ately set trigger sensitivity settingsand lung hyperinflation. When thetrigger sensitivity setting is set toonegative, the patient must useincreased respiratory muscle workto trigger the breath.34 Triggeringmechanisms for delivering breathsare based on detecting either a pres-sure change or a flow change. Withpressure triggering, the machine

sensitivity setting is commonly setso that the patient needs to generateonly a minimal negative pressure (-1or 2 cm) to trigger the breath. Withflow triggering, continuous flow ismaintained through the circuit andthe ventilator is triggered once thepatient is able to generate a presetinspiratory flow. Flow triggering hasbecome the default triggeringmethod; however, just like pressuretriggering, setting the sensitivitylevel too sensitive can cause machinecycling without patient effort (auto-cycling) or failure to cycle.39 Patientswith high V· E and obstructive airwaydisease can have lung hyperinflation,also referred to as intrinsic PEEP,auto-PEEP, or “air trapping.” Patientswith intrinsic PEEP will have difficulty


Table 4 Potential causes and suggested management of patient-ventilator dyssynchrony

Ventilator dyssynchrony

1. Trigger phaseTrigger setting delayed orineffective in triggeringbreath; auto-triggering

2. Flow delivery phaseInspiratory delivery of airtoo slow or fast

3. Breath cycling off phaseExhalation timing appears tobe “out of sync” withpatient’s attempt to exhale

Goals

Patient exhibits easy ability to trigger ventilator breath

Appears comfortable, conveysbreathing comfort

Inspiratory flow of gas matchespatient’s inspiratory effort

Patient appears comfortable,conveys breathing comfort

Ventilator breath terminateswhen patient ends inspiratoryeffort

Ventilator exhalation phasecoincides with patient’s exhalation phase

Patient appears comfortable,conveys breathing comfort

Management

Prevent, manage lung hyperin-flation by decreasing tidal vol-ume, changing inspiratory andexpiratory phase parameters,switching to another mode,and correcting physiologicalabnormalities that increase air-way resistance

Change to another mode of ven-tilation

Correct air leaks in patientor ventilator system

Adjust flow rate setting to meetinspiratory demands, perhapsby setting a higher inspiratoryflow rate or shorter inspiratorytime to deliver air faster if thepatient has a high respiratoryrate and is working hard tobreathe during inspiration

Adjust flow, volume, and/or respiratory rate setting to meetpatient’s needs

Change to other mode of ventilation

Causes

Trigger sensitivity set too highor low

Lung hyperinflation or “airtrapping”

Air leaks that cause loss ofpositive end-expiratorypressure and automaticcycling of ventilator

Inspiratory flow, inspiratorytime, or inspiratory to expi-ratory ratio setting too lowor high

Inspiratory flow, tidal volume,and/or respiratory rate set-tings are affecting expiratorytiming



triggering the ventilator because ofthe need to create additional inspi-ratory muscle effort to reduce theairway pressure to the ventilatortrigger level.40,41 Wasted breathingefforts trying to trigger the ventila-tor can significantly increase thework of breathing.

Adverse effects of air trappinginclude increased intrathoracic pres-sure. Increased thoracic pressure canimpede systemic blood return to theheart with resulting deterioration ofblood pressure and cardiac output.The patient can be disconnectedfrom the ventilator to check for anincrease in blood pressure in casesof ventilator-related hypotension.42

When the ventilator is initially dis-connected, carefully observe forprolonged expiration of air andimmediate clinical improvement,which can be diagnostic for lunghyperinflation. Do not hyperventi-late with the manual resuscitationbag; rather, one should time thecompressions with the bag to matchthe patient’s inspiratory efforts. Ifthe patient immediately improveswith manual ventilation (and auto-PEEP is excluded), the likely problemis the ventilator settings or circuit.12

The primary intervention should beto implement aggressive measuresto correct physiological abnormali-ties that create increased airwayresistance and intrinsic PEEP. Theventilator should be reassessed forproper function and, after thepatient is reattached, appropriatelyadjusted. Adjustments may includechanging inspiratory and expiratoryphase parameters, switching toanother mode, or increasing the setPEEP to the level of auto-PEEP.Increasing the ventilator PEEP levelputs the sensitivity at a low, “easy to

trigger” level again, making the ven-tilator more responsive to breathingefforts, but it may not eliminateineffective triggering.43

Auto-Triggering. Patients exhibit-ing an unexplained high respiratoryrate, but not making inspiratorymuscle efforts visually or by ventila-tor readings, should be evaluatedfor a sensitivity setting that is toolow and may be causing the machineto self cycle (auto-trigger). Auto-triggering can also be caused by airleaks, which cause loss of Vt andPEEP. In situations where PEEP isset, the machine sensitivity settingautomatically readjusts to a positivevalue to maintain a minimal triggerlevel. For example, if PEEP is set at5 cm, the sensitivity setting auto-matically readjusts to +3 or +4 cm.Air leaks in the patient or ventilatorsystem cause loss of PEEP, whichcreates auto-triggering if the sensi-tivity is set at a positive level. If thisproblem goes unrecognized, thepatient may be given unnecessarilyhigh amounts of sedatives and neu-romuscular blocking agents todecrease the respiratory rate andcorrect the respiratory alkalosiswhen the correct solution is to rec-ognize the machine self-cyclingproblem and make appropriateadjustments in the sensitivity set-ting or correct air leak problems.

Insufficient Inspiratory FlowDelivery. Critically ill patients com-monly have high respiratorydemands, resulting in the need forhigher inspiratory flow rates. Theinspiratory flow, inspiratory time,or inspiratory to expiratory ratiosetting determines the speed withwhich air is delivered to the patient.Setting a higher inspiratory flowrate or a shorter inspiratory time

delivers the air faster on inspira-tion. Breathing can be very uncom-fortable if the inflation time is settoo short or too long. The patientmay be on a full ventilator supportmode yet be in severe acute respira-tory distress and working hard tobreathe if the peak flow is too lowand the patient is demanding moregas than the ventilator is set up tosupply. It is essential to adjust theventilator flow rate setting to matchthe patient’s inspiratory demands.These adjustments may need to bemade frequently if the patient’s res-piratory status is labile.

Automatic tube compensation,a feature on some ventilators, appliesa positive pressure to compensatefor endotracheal tube resistanceand may overcome work of breath-ing imposed by the endotrachealtube, improve patient-ventilatorsynchrony by varying flow as thepatient’s demand changes, andreduce air trapping by compensat-ing for imposed expiratory resist-ance.44 Several variables are enteredinto the ventilator system to achieveautomatic tube compensation,including tube type, diameter, per-centage of support, and trigger sen-sitivity. Although automatic tubecompensation may be helpful forthe uncomfortable, dyssynchronouspatient with high inspiratory flowdemands who is on high levels ofpressure support ventilation,45,46

entering incorrect information cancause respiratory discomfort anddyssynchrony. For example, settingan internal tube diameter lowerthan the actual diameter leads toovercompensation by the ventilator.Setting a diameter higher than theactual tube diameter leads to under-compensation. Narrowing of the




tube due to accumulation of secre-tions or kinks in the endotrachealtube causes inaccurate calculations47

and suboptimal performance of theautomatic tube compensation fea-ture. The patient should be continu-ally monitored for increased work ofbreathing and adequacy of ventila-tion, such as Vt and respiratory rate.47

Double Triggering of the Ventilator.Double triggering, also known asbreath stacking, is the delivery of 2consecutive ventilator cycles sepa-rated by a very short expiratorytime. This situation can occur if theVt is set too low or the ventilatorydemand is high and the inspiratorytime set on the ventilator is shorterthan the patient’s inspiratory time.The patient’s effort is not completedat the end of the first ventilatorbreath, and a second ventilator cycleis triggered. The problem occursmore commonly in assist/controlmodes, where inspiratory flow ratesare fixed.38 Double triggering maycause excessive lung pressures andVt delivery. It can also aggravatehyperinflation, increasing the bur-den on respiratory muscles.9 Thepatient appears to be dyssynchro-nous with the ventilator duringinspiratory efforts, triggering anextra ventilator breath. Peak inspi-ratory airway pressure may be higherand may set off the upper airwaypressure alarm. Because the goalsare to reduce work of breathing andmaintain safe lung pressures, man-agement includes adjustment ofinspiratory time to match inspiratoryefforts and changing to pressure-targeted modes of ventilation.48

In volume-targeted modes, itmay also be possible to increase theinspiratory time or Vt in small incre-ments to the point where double

triggering stops without creatingundesirable high alveolar (lung) pres-sures. The appropriately adjustedVt may completely result in cessa-tion of all breathing efforts andappearance of breathing comfort.Other measures to strictly controlundesirable lung volumes and pres-sures include sedation and/orchemical paralysis.

Dyssynchrony in ExhalationPhase. Expiration timing is affectedby the inspiratory flow, Vt, and res-piratory rate settings. For example,the patient breathing fast on a volume-control mode needs a highinspiratory flow rate and will be outof sync, as exhibited by the patienttrying to exhale when the machineis still delivering the inspiration.Exhalation timing appears to be outof sync with the patient’s attempt toexhale. Observations include workof breathing during exhalation withforced abdominal contractions. Ifthe upper airway pressure alarmsounds, less Vt is delivered and mayworsen this vicious cycle. Adjustingthe machine to match inspiratoryflow demands or changing toanother ventilation mode mayresolve the problem.

Achieving Optimal Patient-Ventilator Care

Comprehensive education aboutventilator modes, function of dials,and various skills to prevent and man-age various patient- and ventilator-related problems promotes optimalpatient-centered care. Meaningfuleducational programs support com-petent performance49 and empowernurses to be more proactive in thecare of patients receiving mechani-cal ventilation. Teaching and evalu-ating clinical know ledge, skills, and

problem-solving abilities shouldinclude didactic and interactiveactivities with regular training ses-sions to prevent the decrease in per-formance that may occur with time.50

Ventilator simulator sessions in smallgroups can be incorporated as ateaching strategy for learning how totroubleshoot patient- and ventilator-related problems. Simulations couldinclude use of a test balloon or com-mercial simulator. Learning wouldbe enhanced by the student breath-ing through the ventilator circuitand actually experiencing the effectsof various ventilator modes, dialadjustments, and simulated prob-lems that cause alarm situations.Competency assessment toolsshould be evaluated to determinetheir benefit in assessing and main-taining respiratory care skills andimproving patients’ outcomes(Table 5). Orientation programsabout the ventilator and patientmanagement, including a mechani-cal ventilation learning laboratory,can be evaluated to determinewhether they meet desired outcomes.

Many decisions regarding venti-lator purchase for hospitals aremade by respiratory therapists andphysicians. Although newer, moreadvanced ventilators may be desir-able for complex cases, attemptsshould be made to avoid using vari-ous ventilator brands. When severaldifferent ventilators are used in thehospital, it may impair the abilityof nurses, respiratory therapists,and medical staff to achieve andmaintain the unique knowledge andskills necessary to provide optimalventilator management.

Basic competencies should beachieved in order to provide expertcare to ventilator-dependent patients.

www.ccnonline.org CriticalCareNurse Vol 31, No. 3, JUNE 2011 41 at OREGON HEALTH SCIENCES UNIV on October 1, 2012ccn.aacnjournals.orgDownloaded from


Ventilator-specific “user friendly”quick reference guides, as presentedin Table 6, can be provided duringstaff education and made availableon each unit for reference. A pictureof the ventilator’s front control panelwith a brief definition and descrip-tion of dials and displays should also

be provided to staff. Comprehensivepatient-ventilator troubleshootingguides are also available for educa-tion and reference.52-54

SummaryNurses must be knowledgeable

about the function and limitationsof ventilator modes, causes of respi-ratory distress and dyssynchronywith the ventilator, and appropriatemanagement in order to providehigh-quality patient-centered care.It is essential that critical care nursesstrive to develop the knowledge andskills necessary for comprehensive

and successful management ofpatients receiving ventilatory sup-port. The health care team involvedin the different aspects of ventilatorcare should collaborate and sharetheir unique expertise with thegoals of meeting the patient’sneeds, optimizing patients’ com-fort, and preventing complicationsduring mechanical ventilation. CCN


Table 5 Basic skill competencies for the care of ventilator-dependent patients

Competency

Speaks directly to patient when providing any care

Sets up manual resuscitation bag including adjustment of fraction of inspired oxygen (FIO2)

Demonstrates correct ventilation with manual resuscitation bag

Verbalizes assessments used to determine whether patient requires suctioningDemonstrates correct suction procedure (open and closed suction catheter system)Educates patient as appropriate on purpose of suctioning, anticipated sensations, interventions to decrease

discomfort

Articulates plan for oral careDemonstrates correct oral care techniques

Verbalizes methods used to communicate effectively with patient Verbalizes usual questions to ask when patient conveys that something is needed Articulates the communication care plan for individual patients Uses communication aids/devices appropriately to explore patient’s needsDemonstrates clinical performance with a variety of patients

Verbalizes assessments indicating properly secured endotracheal tube, tracheostomy tube; properlysecures endotracheal or tracheostomy tube; meticulous skin care and skin assessment

Repositions endotracheal tube

Positions tubing on ventilator arm in manner that maintains optimal tube alignment and prevents pullingand tube movement

Turns patient in manner that avoids pulling or jarring of tube

Provides call light system for patient before leaving room

Discusses appropriate use of sedatives and pain medications with ventilator patients

Verbalizes causes for following alarms/conditionsDemonstrates corrective actions for following alarms/conditions

a. High pressureb. Low exhaled volumec. Low inspiratory pressured. Apneae. Disconnectionf. Unplanned extubation

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To learn more about mechanical ventilation,read “International Perspectives on the Influ-ence of Structure and Process of WeaningFrom Mechanical Ventilation” in the Ameri-can Journal of Critical Care, 2011;20:e10-e18.doi:10.4037/ajcc2011430. Available atwww.ajcconline.org.




Table 6 Quick reference guide: patient-ventilator-related problems/managementa

Alarm problem

1. High pressureAlarm occurs if 2 consecutive breaths

are limited because they reach the highpressure setting; inspiratory pressurephase ends (no more volume is deliv-ered) and the exhalation valve opens toprevent excessive pressure (determinedby upper pressure alarm limit that wasset)

Continuous hi pres (high pressure)Alarm registers if pressures do notdecrease to below high pressure setting

2. Low ex (exhaled) tidal volumeAlarm occurs if delivered tidal volume

less than low tidal volume alarm set-ting for 3 or 4 consecutive breaths

3. Low insp (inspiratory) pressureAlarm occurs if monitored circuit pres-

sure is low—below setting on low inspi-ratory pressure dial

5. Apnea Alarm occurs if patient has not triggered

a breath within the 20-second apneainterval; can occur only in spontaneousmode-pressure support ventilation

6. DisconnectAlarm occurs if measured exhaled tidal

volume is 15% or less of delivered volume for 4 consecutive breaths

7. Vent inop (Ventilator inoperable)Alarm occurs if hardware failure or

critical software error that could com-promise safe ventilation. Safety valveopens → state allows patient tobreathe only room air unassisted

8. Air intake blocked Alarm occurs if ventilator has detected

above-normal resistance at the airintake filter (back of machine)

9. Fan failed alertAlarm occurs if fan filter is occluded or

fan is not operational

Causes

Blocked or kinked tube, otherincreased airway resistanceand/or decreased lung compli-ance factors that increase peakairway pressure to above limit,resulting in prescribed volumenot being delivered

Attempting to speak, inability tocommunicate wants, needs

Biting down on orally placedtube resulting in peak airwaypressure alarming, potential fordecreased tidal volume delivery

Air leaks due to loose, discon-nected ventilator circuit or nebulizer connections, tear orcrack in tubing; cuff leak

Air leaks causing volume loss

Apnea, unstable ventilatory drivebecause of medicationsdepressing central nervoussystem, clinical condition

Major air leaks: circuit disconnect,major cuff leak

Hardware failure or critical soft-ware error

Back of ventilator occluded

Ventilator not warmed up or fanfilter occluded

Interventions

Suction secretions as neededEnsure water condensation from tubing does not drain

into patient’s airwayPrevent tube jarring and movement during turning patient

and disconnecting and reconnecting ventilator adapterAdminister bronchodilators as ordered

Implement effective communication system (see articleby Grossbach et al19 in this issue of Critical Care Nurse)

Explain why not to bite down on tube, remind asneeded; may be able to place tube in edentulous areaof mouth; use tube securing method with bite block ifneeded

Evaluate patient, make sure attached to ventilatorAssess, correct air leaks in endotracheal, tracheostomy

cuff, ventilator system; recheck ventilator to makesure prescribed tidal volume is delivered; call forassistance as needed

Correct problems causing high airway pressures asoutlined in problem 1

Ventilate manually if patient is in acute respiratory dis-tress and unable to immediately correct problem

Check all tubing connections (including temperatureprobe, nebulizer attachment sites) to make sure tight,and secure as needed

Evaluate, inflate cuff as needed for leaksReevaluate ventilator to make sure patient is receiving

prescribed tidal volume

Assess, correct air leaks in endotracheal, tracheostomycuff, ventilator system

Recheck ventilator to make sure prescribed tidal volumeis delivered; call for assistance as needed

Check patient, ventilate manually as neededMay need to switch to mode that provides more

ventilation supportReevaluate need for medications that are depressing

ventilation

Evaluate patient for major air leak (ventilator circuit disconnection), connect circuit

Correct cuff leak problems Obtain assistance, ventilate manually as needed

Ventilate manually; call respiratory therapyRespiratory therapist must evaluate/retest ventilator for

proper function

Check patient; ventilate manually as neededCheck for visible occlusions (curtain, clothing, or furni-

ture blocking the air intake at back of machine); donot cover back of ventilator—keep open to air

Make sure ventilator has warmed up sufficientlyRespiratory therapist should check fan filter for occlu-

sions and clean as needed; replace air intake filter ifneeded

Press alarm reset key; if this does not resolve problem,change ventilator

a List of alarm problems in left column adapted from Puritan Bennett 700 Series Operator’s Manual.51



Financial DisclosuresNone reported.

References1. Huang YT, Singh, J. Basic modes of mechan-

ical ventilation. In: Peters J, Papadakos BL,eds. Mechanical Ventilation: Clinical Applica-tions and Pathophysiology. Philadelphia, PA:Saunders; 2008:247-268.

2. Pierson DJ. A primer on mechanical ventila-tion. 2008. http://courses.washington.edu/med610/mechanicalventilation/mv_primer.html. Accessed February 25, 2011.

3. Burns SM. Mechanical ventilation andweaning. In: Carlson K, ed. AACN AdvancedCritical Care Nursing. St Louis, MO: Saun-ders Elsevier; 2009:469-492.

4. Chatburn RJ. Classification of ventilatormodes: update and proposal for implemen-tation. Respir Care. 2007;52(3):301-323.

5. MacIntyre NR, Branson, RD. MechanicalVentilation. 2nd ed. Philadelphia, PA: Else-vier; 2009.

6. MacIntyre NR. Controversies in mechanicalventilation. Clin Chest Med. 2008;29(2):225-356.

7. Burns SM. AACN Protocols for Practice: Careof Mechanically Ventilated Patients. 2nd ed.Boston, MA: Jones and Bartlett Publishers;2007.

8. Rose L. Advanced modes of mechanical ven-tilation. AACN Adv Crit Care. 2006;17(2):145-158.

9. Tobin MJ. Principles and Practice of Mechani-cal Ventilation. 2nd ed. New York, NY:McGraw-Hill; 2006.

10. Branson RD, Johannigman JA. What is theevidence base for the newer ventilationmodes? Respir Care. 2004;49(7):742-760.

11. Bozyk R, Hyzy RC. Modes of mechanicalventilation. Up to Date. Last updated April30, 2010. http://www.utdol.com/online/content/topic.do?topicKey=cc_medi/7480. Accessed February 25, 2011.

12. Santanilla JI, Daniel B, Yeow ME. Mechani-cal ventilation. Emerg Med Clin North Am.2008;26(3):849-862.

13. Brochard L, Haraf A, Lorino H. Inspiratorypressure support prevents diaphragmaticfatigue during weaning from mechanicalventilation. Am Rev Respir Dis. 1989;139(2):513-521.

14. MacIntyre NR. Is there a best way to set tidalvolume for mechanical ventilatory support?Clin Chest Med. 2008;29:225-231.

15. MacIntyre NR. Guidelines for alternativemodes of ventilation used in the managementof patients with ARDS. http://www.thoracic.org/clinical/critical-care/salvage-therapies-h1n1/pages/alternative-modes.php.Accessed March 3, 2011.

16. Ryland PB, Roy TM, Kosseifi SG. Ventilation,mechanical. http://emedicine.medscape.com/article/304068-overview. UpdatedApril 13, 2010. Accessed February 25, 2011.

17. St John RE, Burns SM. Airway and ventilatorymanagement. In: Chulay M, Burns S, eds.AACN Essentials of Progressive Care Nursing.New York, NY: McGraw-Hill; 2007:87-124.

18. Grossbach I. Mechanical ventilation. In:Geiger-Bronsky M, Wilson D, eds. Respira-tory Nursing: A Core Curriculum. New York,NY: Springer Publishing Co; 2008:497-523.

19. Grossbach I, Stranberg S, Chlan L. Promot-ing effective communication for patientsreceiving mechanical ventilation. Crit CareNurse. 2011;31(3):46-61.

20. Grossbach I. AACN Clinical Simulations:Pulmonary System. CD-ROM for Windows4.0. Philadelphia, PA: Lippincott Williams &Wilkins; 2001.

21. DelFabbro E, Dalai S, Bruera E. Symptomcontrol in palliative care—part 111: dysp-nea and delirium. J Palliat Med. 2006;9(2):422-436.

22. Schwartzstein RM. Language of dyspnea.In: Mahler DA, O’Donnell DE, eds. Dysp-nea. Boca Raton, FL: Taylor & Francis; 2005.

23. Williams M, Cafarella P, Olds T, et al. Thelanguage of breathlessness differentiatesbetween patients with COPD and age-matched adults. Chest. 2008;134(3):489-496.

24. Mahler DA, Baird JC. Are you fluent in thelanguage of dyspnea? Chest. 2008;134(3):476-477.

25. Spector N, Connolly MA, Carlson KK. Dys-pnea: applying research to bedside practice.Crit Care Nurse. 2007;18(1):45-60.

26. American Thoracic Society. Dyspnea: mech-anisms, assessment, and management: aconsensus statement. Am J Respir Crit CareMed. 1999;159:321-340.

27. Hansen-Flaschen JH. Dyspnea in the venti-lated patient: a call for patient-centered ven-tilation. Respir Care. 2000;45(12):1460-1467.

28. Karampela I, Hansen-Flaschen J, Smith S,Reily D, Fuchs BD. A dyspnea evaluationprotocol for respiratory therapists: a feasi-bility study. Respir Care. 2002;47(10):1158.

28. Spector N, Klein D. Chronic critically illdyspneic patients: mechanisms and clinicalmeasurement. AACN Clin Issues. 2001;12(2):220-233.

30. Powers J, Bennett SJ. Measurement of dysp-nea in patients treated with mechanical ven-tilation. Am J Crit Care. 1999;8(4):254-261.

31. MacIntyre N. New advances in mechanicalventilation. http://www.medscape.org/viewarticle/568522. Published January 15,2008. Accessed February 25, 2011.

32. Kondili E, Prinianakis G, Georgopoulos D.Patient-ventilator interaction. Br J Anaesth.2003;91:106-119.

33. Kondili E, Akoumianaki E, Alexopoulou C,Georgopoulos D. Identifying and relievingasynchrony during mechanical ventilation.Expert Rev Respir Med. 2009;3(1):231-243.

34. Thille AW, Brochard L. Promoting patient-ventilator synchrony. Clin Pulm Med. 2007;14(10):350-359.

35. deWit M, Miller K, Green D, et al. Ineffec-tive triggering predicts increased durationof mechanical ventilation. Crit Care Med.2009;37(10):2740-2745.

36. Mellott KG, Graap MJ, Munro CL, et al.Patient-ventilator dyssynchrony: clinicalsignificance and implications for practice.Crit Care Nurse. 2010;29(6):41-56.

37. Robinson BRH, Branson RD. Consequencesof ventilator asynchrony: why can’t we all getalong? Crit Care Med. 2009;37(10):2848-2849.

38. Thille AW, Rodriguez P, Cabello B. Patient-ventilator asynchrony during assistedmechanical ventilation. Int Care Med. 2006;32(10):1515-1522.

39. France T. Flow trigger vs pressure trigger.Respir Therapy. 2007;2(5):36.

40. Dhand R.Ventilator graphics and respiratorymechanics in the patient with obstructivelung disease. Respir Care. 2005;50(2):246-259.

41. Blanch L, Bernabe F, Lucangelo U. Measure-ment of air trapping, intrinsic positive end-expiratory pressure, and dynamichyperinflation in mechanically ventilatedpatients. Respir Care. 2005;50(1):110-123.

42. Wiener CM, Fauci AS, Braunwald E, et al.Harrison’s Principles of Internal Medicine.17th ed. New York, NY: McGraw-Hill Com-panies, Inc; 2008.

43. Amanullah S, Beaulieu KA. Ventilatorgraphics. http://emedicine.medscape.com/article/305120-overview. Updated June11, 2008. Accessed February 25, 2011.

44. Bonetto C, Calo MN, Delgado MO,Mancebo J. Modes of pressure delivery andpatient-ventilator interaction. Respir CareClin North Am. 2005;11(2):247-263.

45. Marini JJ, Wheeler AP. Critical Care Medicine:The Essentials. 3rd ed. Philadelphia, PA:Lippincott Williams & Wilkins; 2006:129.

46. Vitacca M, Bianchi L, Zanotti E, et al.Assessment of physiologic variables andsubjective comfort under different levels ofpressure support ventilation. Chest. 2004;126(3):851-859.

47. Unoki T, Serita A, Grap MJ. Automatic tubecompensation during weaning from mechan-ical ventilation: evidence and clinical impli-cations. Crit Care Nurse. 2008;28(4):34-42.

48. Kallet RH, Luce JM. Detection of patient-ventilator asynchrony during low tidal vol-ume ventilation using ventilator waveformgraphics. Respir Care. 2002;47(2):183-187.

49. Schmalenberg C, Kramer M, Brewer BB, et al.Clinically competent peers and support foreducation: structures and practices thatwork. Crit Care Nurse. 2008;28(4):54-65.

50. Harrison J, Selhorst D, Penfil S, Cullen E,Rendle J, Hertzog J. Ongoing respiratorycare practitioner education: evaluation of amechanical ventilation learning laboratory[abstract]. Respir Care. www.rcjournal.com/abstracts/2002/?id=OF-02-072. Published2002. Accessed February 25, 2011.

51. Puritan-Bennett 700 Series Ventilator SystemOperator’s Manual. St Louis, MO: Mallinck-rodt, Inc: March 1999.

52. Grossbach I. Management of patient-ventilator related problems, part 1. CritCare Nurse. 1986;6(4):58-70.

53. Grossbach I. Management of patient-venti-lator related problems, part 2. Crit CareNurse. 1986;6(5):64-79.

54. Grossbach I. Ventilator troubleshootingguide. In: Chulay M, Burns S, eds. AACNEssentials of Progressive Care Nursing. NewYork, NY: McGraw-Hill; 2007:487-497.




CE Test Test ID C31132: Overview of Mechanical Ventilatory Support and Management of Patient- and Ventilator-Related ResponsesLearning objectives: 1. Differentiate various (common) modes of mechanical ventilation 2. Identify management strategies for patient responses to mechanical ventilatory support 3. Discuss assessments and causes of patient-ventilator dyssynchrony

Program evaluationYes No

Objective 1 was met � �Objective 2 was met � �Objective 3 was met � �Content was relevant to my

nursing practice � �My expectations were met � �This method of CE is effective

for this content � �The level of difficulty of this test was: � easy � medium � difficult

To complete this program, it took me hours/minutes.

Test answers: Mark only one box for your answer to each question. You may photocopy this form.

1. When the flow rate to deliver tidal volume during inspiration is sethigher, which of the following results?a. The speed of gas delivery is slower and inspiratory time is shorterb. The speed of gas delivery is faster and inspiratory time is longerc. The speed of gas delivery is faster and inspiratory time is shorterd. The speed of gas delivery is slower and inspiratory time is longer

2. Which of the following best describes the volume of gas inhaled orexhaled during a breath?a. Minute ventilationb. Peak flow ratec. Tidal volumed. Functional residual capacity

3. What is the minute ventilation on assist-control mode if the cliniciansets the tidal volume at 700 mL and the respiratory rate at 12 breathsper minute?a. 5 L/minute c. 7 L/minuteb. 6.4 L/minute d. 8.4 L/minute

4. Which of the following is a volume-targeted ventilator mode?a. Volume variableb. Fixed inspiratory flow ratec. Preset pressure deliveryd. Fixed peak airway pressure

5. Which of the following is a pressure-targeted ventilator mode?a. Assist/controlb. Pressure controlc. Continuous mandatory ventilationd. Controlled mandatory ventilation

6. Which of the following factors increases airway resistance?a. Bronchospasmb. Pneumoniac. Atelectasisd. Pneumothorax

7. Which of the following factors decreases lung compliance?a. Tachypneab. Pulmonary edemac. Airway secretionsd. Cough

8. Which of the following is a potential result of inappropriate inter-vention in the anxiety-shortness of breath cycle?a. Hypoxemia and metabolic alkalosisb. Hypercapnia and metabolic acidemiac. Hypoxemia and respiratory acidemiad. Hypercapnia and metabolic alkalosis

9. Which of the following alarm problems is caused by a blocked orkinked endotracheal tube?a. Apnea c. Low exhaled tidal volumeb. Low inspiratory pressure d. High pressure

10. Which of the following observations indicates that the ventilatorflow rate setting matches the patient’s inspiratory efforts?a. Easy ability of the patient to trigger the breath and delivery of the

breath coincides with inspiratory effortsb. Easy ability of the patient to trigger the breath and neck accessory

muscle use during inspirationc. Effort required to trigger the breath with respiratory muscle contractions

during inspirationd. Effort required to trigger the breath with respiratory muscle

contractions during inspiration and expiration

11. Which of the following changes should be made to match theinspiratory demands of a patient breathing fast?a. Set a lower inspiratory flow rate or a longer inspiratory time to deliver

the breath slower on inspirationb. Set a higher inspiratory flow rate or a shorter inspiratory time to

deliver the breath faster on inspirationc. Coach the patient to relax and slow down breathing to coincide with the

ventilator breathd. Readjust the sensitivity setting on the ventilator to help slow down

breathing

12. What is the potential result of alarm silencing once or repeatedalarm silencing?a. No problem as long as the patient does not exhibit signs and symptoms

of respiratory distressb. Severe acute respiratory academia, which can lead to cardiovascular

decompensation and cardiac arrestc. Severe hypoxemia and acute metabolic alkalosisd. Acute metabolic acidosis

For faster processing, takethis CE test online atwww.ccnonline.org

(“CE Articles in this issue”)or mail this entire page to:

AACN, 101 Columbia Aliso Viejo, CA 92656.

Test ID: C31132 Form expires: June 1, 2013 Contact hours: 1.0 Fee: AACN members, $0; nonmembers, $10 Passing score: 9 correct (75%) Synergy CERP: Category A Test writer: Denise Hayes, RN, MSN, CRNP

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SignatureThe American Association of Critical-Care Nurses is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center’s Commission on Accreditation.

AACN has been approved as a provider of continuing education in nursing by the State Boards of Nursing of Alabama (#ABNP0062), California (#01036), and Louisiana (#ABN12). AACN programming meets the standards for most other states requiring mandatory continuing education credit for relicensure.

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