PowerPoint
Presented By :-HAIFAAEffects of Mechanical Ventilation onPATIENT
BODY
OUTLINEOBJECTIVESINTRODUCTIONMechanical ventilationModes of
VentilationIndications for mechanical ventilationGOALS OF
MECHANICAL VENTILATIONEffects of Mechanical Ventilation on
RESPIRATORY SYSTEMEffects of Mechanical Ventilation on
Cardiovascular systemEffects of Mechanical Ventilation on RENAL
SYSTEMEffects of Mechanical Ventilation on CNSEffects of Mechanical
Ventilation on GASTROINTESTINALEffects of Mechanical Ventilation on
Large BowelEffects of Mechanical Ventilation on Liver and
GallbladderEffects of Mechanical Ventilation on SLEEPOTHER Effects
of Mechanical Ventilation MONITORINGsummary
OBJECTIVES
What is the Mechanical Ventilation What are Mechanical
Ventilation modesWhat are the Indications for mechanical
ventilationIdentify the GOALS OF MECHANICAL VENTILATIONIdentify the
Effects of Mechanical Ventilation on patient body
INTRODUCTIONHuman heart is functionally divided into right and
left side. Each side may be further subdivided into a ventricle and
an atrium. The primary function of each atrium is to act as a
reserviour and booster pump for venous return to the heart. And ,
the primary physiological function of each ventricle is to maintain
circulation of blood to the organs of the body .
Mechanical ventilationMechanical ventilation, in the healthcare
setting or home, helps patients breathe by assisting the inhalation
of oxygen into the lungs and the exhalation of carbon dioxide.
Depending on the patients condition, mechanical ventilation can
help support or completely control breathing
Modes of VentilationAssist/control (A/C)Continuous positive
airway pressure ventilation (CPAP)Synchronized intermittent
mandatory ventilation (SIMV)Pressure control ventilation (PCV or
PC)Positive end expiratory pressure (PEEP)Pressure support
ventilation (PSV or PS)
Indications for mechanical ventilationVentilatory failure
Oxygenation failure Excessive ventilatory workload Impending
respiratory failure
VENTILATORY FAILUREDrug overdose Spinal cord injury Head injury
& strokeNeuromuscular dysfunctionSleep disorders Acute airflow
obstruction Chest traumaPostoperative thoracic & upper
abdominal Electrolyte imbalance General anaesthesia
OXYGENATION FAILURE &INCREASED VENTILATORY WORKLOADAcute
lung injury/ARDS Acute severe airflow obstruction Dead space
ventilation Shunts Congenital heart diseases Shock High metabolic
rate & Obesity General anaesthesia & Postop
GOALS OF MECHANICAL VENTILATIONMaintain patient comfort Allow a
normal, spontaneous breathing pattern whenever possible Maintain a
PaCO between 35 - 45 mmHg Maintain a PaO sufficient to meet
cellular O demands but avoid oxygen toxicity Avoid acid-base and
electrolyte imbalances Avoid respiratory muscle fatigue and
atrophy
Effects of Mechanical Ventilation onRESPIRATORY
SYSTEMRespiratory systemdecreased lung compliancemore uneven
distribution of ventilationincrease in dead space and in ratio of
dead space to tidal volumePatients with normal lungsfall in FRC and
increased alveolar to arterial oxygen gradientdue to extensive
dependent atelectasisPatients with abnormal lungsin patients who
have been hypoventilating near residual volume, mechanical
ventilation will increase FRC and tidal volume
Effects of Mechanical Ventilation on Cardiovascular system
Positive pressure ventilation results in:rise in pleural
pressurerise in intra-abdominal pressureincreased lung volumes
The extent of these changes relative to any given level of
airway pressure will depend on the lung and chest wall compliance
and airway resistanceIn any individual patient the overall effects
will depend on the patient's underlying pathophysiology.
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Effects of Mechanical Ventilation on Cardiovascular
systemPreloadLV preload is usually (but not invariably) reduced by
a variety of mechanismsVenous returnin a volume resuscitated
patientvenous return does not fallintrathoracic pressure is
positive rather than negative butintra-abdominal pressure also
risespressure gradient between abdomen and thorax is maintainedin a
patient with an open abdomenvenous return should
fallintra-abdominal pressure does not risepressure gradient not
maintained
Effects of Mechanical Ventilation on Cardiovascular
systemchanges in LVEDV do not necessarily parallel changes in
RVEDVRV and LV confined by pericardiumas a result increase in RVEDV
decreases LV compliance and vice versain a patient with pulmonary
hypertension a reduction in venous return as a result of positive
pressure ventilation will reduce the size of a dilated RV and hence
increase LV compliance and LV preload
Effects of Mechanical Ventilation on Cardiovascular
systemPulmonary vascular resistancedecreased RV stroke volume and
hence LV preload because of compression of pulmonary vessels by
positive alveolar pressureLV complianceat high lung volumes lungs
compress the heart reducing LV compliance and hence LV
end-diastolic volumeAfterloadafterload = wall tension (T) during
contraction
where Ptm= transmural pressure, R=radius and H=wall
thicknesstransmural pressure=intraventricular pressure-pleural
pressurepleural pressure increased by positive pressuretherefore
transmural pressure and afterload must be decreased by positive
pressure ventilation
Effects of Mechanical Ventilation on Cardiovascular
systemMyocardial oxygen consumptionmyocardial oxygen consumption
was previously thought to be determined by stroke work. However it
is now known that it is determined by the sum of stroke work and
elastance-defined potential work. The latter is the potential
energy in the ventricle at end-systole. Figure below illustrates
this relationship. Myocardial oxygen consumption is proportional to
the shaded area. As mechanical ventilation generally decreases
preload and afterload it shifts the pressure-volume loop to the
left and down decreasing elastance-defined potential work and thus
myocardial oxygen consumption.
in patients with coronary artery disease reducing myocardial
oxygen consumption may improve the balance between oxygen demand
and supply resulting in an improvement in LV function. Thus in
these patients mechanical ventilation may increase LV
contractility.
Effects of Mechanical Ventilation on Cardiovascular
systemCardiac outputoverall effect depends on whether ventricle is
normal or abnormalin a patient with normal LV contractility
increased intrathoracic pressure decreases LVEDV more than LVESV
resulting in a fall in stroke volumein a patient with decreased LV
contractility, intrathoracic pressure decreases LVEDV less than
LVESV resulting in a rise in stroke volume (figure below). Note the
decreased slope of the end systolic pressure volume relationship
due to decreased contractility
Effects of Mechanical Ventilation on RENAL SYSTEMNot all studies
have shown a decrease in renal blood flow with positive pressure
ventilation. Those patients who are volume depleted are more
susceptible to reduced cardiac output.renal blood flow falls if
cardiac output fallsDecreased sodium secretion due to fall in
cardiac output and decreased secretion of atrial natriuretic
factorIncreased water retention due to increased secretion of ADH,
particularly in children.
Effects of Mechanical Ventilation on RENAL SYSTEMThe usual renal
response to reduction of cardiac output and mean arterial
pressure.Reduction in urine output secondary to a fall in the
transmural pressure of the right atrium that results in reduction
of the secretion of atrial naturitic peptide and the activation of
renin-angiotensin-aldosterone system and pituitary vasopressin
secretion
Effects of Mechanical Ventilation onCNSincreased intrathoracic
pressure decreases venous drainage from head and may increase ICP.
If, however, mechanical ventilation results in a decrease in
PaCO2ICP may actually fallNB adverse effects of mechanical
ventilation are far outweighed by benefits in brain injured
patients
Effects of Mechanical Ventilation on GASTROINTESTINAL
Esophagus,Stomach and Small Intestine
Erosive esophagitis (30-50% of patients ventilated >48
hours)NG tubePoor lower esophageal sphincter tone and refluxOpiates
and adrenergic agonistsDuodenogastroesophageal reflux through the
action of trypsinUpper gastrointestinal hemorrhage:StressDecreased
gastric mucosal protection secondary to a fall in splanchnic blood
flowDecreased motility of stomach and small intestine
Effects of Mechanical Ventilation onLarge Bowel
ConstipationAbdominal distension
Effects of Mechanical Ventilation onLiver and Gallbladder
Reduction in portal venous flow secondary to the fall in cardiac
output.Hepatic engorgement.Reduction in drug clearance secondary to
reduction of hepatic blood flow.
Effects of Mechanical Ventilation on SLEEPDISRUPT SLEEP Noise
disruptionVentilator alarm: inappropriate thresholdDelayed alarm
inactivationHumidifier alarmsDisruption by nursing
interventionsAirway suctionNebulizer deliveryVentilation-related
pharmacological disruption BenzodiazepinesOipoids
OTHER Effects of Mechanical Ventilation DECUBITUS ULCERS
MALNUTRITION
DEPRESSHION & ANXIETY
DELEIRIUM
MONITORINGPhysical examination for all body systems focusing on
the resp system Assess the patient for decreased cardiac output
Administer a sedative as ordered to relax the patient Evaluate the
settings of mechanical ventilator Ensure patient safety
summary EFFECTS OF MECHANICAL VENTILATIONDecrease in venous
return Decrease in cardiac outputDecrease in pulmonary capillary
blood flow Increase in pulmonary vascular resistanceIncrease in
central venous pressureIncreased intracerebral venous
pressureDecreased CSF absorption Increased intraabdominal
pressureIncreased vasopressin secretion
summary EFFECTS OF MECHANICAL VENTILATION Decreased GFR &
urine outputIncreased fluid retentionParadoxical fall in
PaOBarotrauma/volutrauma Ventilator-associated pneumonia Oxygen
toxicityProlonged intubation airway problemsPressure
soresVentilator dependence
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