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MECHANICAL VENTILATION
Soumya Ranjan ParidaBasic B.Sc. Nursing 4th year
Sum Nursing College
PresentationDifferent settings to considerMonitoring of the patientDifferent type of patientCOPD, AsthmaARDS
Trouble shooting
Ventilator settings
Ventilator settings1. Ventilator mode2. Respiratory rate3. Tidal volume or pressure settings4. Inspiratory flow5. I:E ratio6. PEEP7. FiO28. Inspiratory trigger
CMV
A/CV
SIMV
PSV(pressure support ventilation)
Spontaneous inspiratory efforts trigger the ventilator to provide a variable flow of gas in order to attain a preset airway pressure.Can be used in adjunct with SIMV.
Respiratory Rate
1. What is the pt actual rate demand?
Tidal Volume or Pressure setting
Maximum volume/pressure to achieve good ventilation and oxygenation without producing alveolar overdistention
Max cc/kg? = 10 cc/kg
Some clinical exceptions
Inspiratory flowVaries with the Vt, I:E and RR
Normally about 60 l/min
Can be majored to 100- 120 l/min
I:E Ratio
1:2
Prolonged at 1:3, 1:4, …
Inverse ratio
FIO2The usual goal is to use the minimum Fio2 required to have a PaO2 > 60mmhg or a sat >90%
Start at 100%
Oxygen toxicity normally with Fio2 >40%
Inspiratory TriggerNormally set automatically
2 modes:
Airway pressureFlow triggering
Positive End-expiratory Pressure (PEEP)
What is PEEP?
What is the goal of PEEP?
Improve oxygenation
Diminish the work of breathing
Different potential effects
PEEPWhat are the secondary effects of PEEP? Barotrauma Diminish cardiac output
Regional hypoperfusion NaCl retention Augmentation of I.C.P.? Paradoxal hypoxemia
PEEPContraindication:No absolute CI
BarotraumaAirway traumaHemodynamic instability I.C.P.?Bronchospasm?
PEEPWhat PEEP do you want?
Usually, 5-10 cmH2O
Monitoring of the patient
Look at your patientQuestion your pt
Examine your pt
Monitor your pt
Look at the synchronicity of your pt breathing
Pressures
Compliance pressure (Pplat)
Represent the static end inspiratory recoil pressure of the respiratory system, lung and chest wall respectively
Measures the static compliance or elastance
PplatMeasured by occluding the ventilator 3-5 sec at the end of inspirationShould not exceed 30 cmH2O
Peak Pressure (Ppeak)Ppeak = Pplat + Pres
Where Pres reflects the resistive element of the respiratory system (ET tube and airway)
PpeakPressure measured at the end of inspiration
Should not exceed 50cmH2O?
Auto-PEEP or Intrinsic PEEP
What is Auto-PEEP?
Normally, at end expiration, the lung volume is equal to the FRC
When PEEPi occurs, the lung volume at end expiration is greater then the FRC
Auto-PEEP or Intrinsic PEEP
Why does hyperinflation occur?
Airflow limitation because of dynamic collapse
No time to expire all the lung volume (high RR or Vt)
Expiratory muscle activityLesions that increase expiratory resistance
Auto-PEEP or Intrinsic PEEP
Auto-PEEP is measured in a relaxed pt with an end-expiratory hold maneuver on a mechanical ventilator immediately before the onset of the next breath
Auto-PEEP or Intrinsic PEEP
Adverse effects:
Predisposes to barotrauma Predisposes hemodynamic compromises Diminishes the efficiency of the force
generated by respiratory muscles Augments the work of breathing Augments the effort to trigger the ventilator
Different types of patient
COPD and AsthmaGoals:
Diminish dynamic hyperinflationDiminish work of breathingControlled hypoventilation
(permissive hypercapnia)
Diminish DHIWhy?
Diminish DHIHow?Diminish minute ventilation
Low Vt (6-8 cc/kg)Low RR (8-10 b/min)Maximize expiratory time
Diminish work of breathingHow: Add PEEP (about 85% of PEEPi)
Applicable in COPD and Asthma.
Controlled hypercapniaWhy?
Limit high airway pressures and thus diminish the risk of complications
Controlled hypercapniaHow?
Control the ventilation to keep adequate pressures up to a PH > 7.20 and/or a PaCO2 of 80 mmHg
Controlled hypercapniaCI:Head pathologiesSevere HTNSevere metabolic acidosisHypovolemiaSevere refractory hypoxiaSevere pulmonary HTNCoronary disease
A.R.D.S.Ventilation with lower tidal volume as
compared with traditional volumes for acute lung injury and the ARDS
The Acute Respiratory Distress Syndrome Network
N Engl J Med 2000;342:1301-08
MethodsMarch 96 – March 9910 university centersInclusion:Diminish PaO2Bilateral infiltrateWedge < 18
ExclusionRandomized
MethodsA/C 28d or weaning2 groups: 1. Traditional Vt (12cc/kg) 2. Low Vt (6cc/kg)
End point: 1. Death 2. Days of spontaneous breathing 3. Days without organ failure or barotrauma
ResultsThe trails were stopped after 861 pt because of lower mortality in low Vt group
Trouble Shooting
Trouble ShootingDoctor, doctor, his pressures are going up!!!
What is your next step?
Trouble Shooting1. Call the I.T., he will take care of it!2. Where is the staff?3. I dont know this pt, and run!4. Ask which pressure is going up
Trouble ShootingPpeak is up
Look at your Pplat
Trouble ShootingIf your Pplat is high, you are faced with a COMPLIANCE problem
If your Pplat is N, you are faced with a RESISTIVE problem
DD?
Trouble Shooting
Trouble ShootingDoctor, doctor, my patient is very agitated!
What is your next step?
Trouble Shooting1. Give an ativan to the nurse!2. Give haldol 10mg to the patient!3. Take 5mg of morphine for yourself!4. Look at your pt!
Trouble ShootingAt the time of intubation, fighting is largely due to anxiety
But what do you do if pt is stable and then becomes agitated?
Trouble Shooting1. Remove pt from ventilator2. Initiate manual ventilation3. Perform P/E and assess monitoring indices4. Check patency of airway5. If death is imminent, consider and treat
most likely causes6. Once pt is stabilized, undertake more
detailed assessement and management
Trouble Shooting
ConclusionType of patient Tidal Volume RR PEEP FIO2 Ins. Flow I:E Note Note
Normal 10 cc/kg 10 to 12 0 to 5 100%. 60 l/min 1:2.
ARDS 6 cc/kg 10 to 12 5 to 15 100%. 60 l/min 1:2.
COPD 6 cc/kg 10 to 12 5 to 10 100%. 100 to 120 1:3 to 1:4 PH>7.2PCO2 <80 mmhgTrigger to consider
Trauma 10 cc/kg 10 to 12 0. 100%. 60 l/min 1:2.
Pediatric 8-10 cc/kg Varies age 3 to 5 100%. 60 l/min 1:2. Trigger to consider