mechanical ventilation seyed alireza mahdavi. ventilator settings
TRANSCRIPT
Ventilator settings
1. Ventilator mode
2. Respiratory rate
3. Tidal volume or pressure settings
4. Inspiratory flow
5. I:E ratio
6. PEEP
7. FiO2
8. Inspiratory trigger
SpontaneousBreathing
Mechanical Ventilation
Pre
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Time
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CMV
SIMV
Bivent
APRV
CPAP
Concepts and Modes of Mechanical Ventilation
Positive End-expiratory Pressure (PEEP)
What is PEEP?
What is the goal of PEEP?
Improve oxygenation
Diminish the work of breathing
Different potential effects
PEEP
What are the secondary effects of PEEP? Barotrauma Diminish cardiac output
Regional hypoperfusion NaCl retention Augmentation of I.C.P.? Paradoxal hypoxemia
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 than 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
COPD and Asthma
Goals:
Diminish dynamic hyperinflationDiminish work of breathingControlled hypoventilation
(permissive hypercapnia)
Diminish DHI
How?Diminish minute ventilation
Low Vt (6-8 cc/kg)Low RR (8-10 b/min)Maximize expiratory time
Controlled hypercapnia
How?
Control the ventilation to keep adequate pressures up to a PH > 7.20 and/or a PaCO2 of 80 mmHg
Controlled hypercapnia
CI:Head pathologiesSevere HTNSevere metabolic acidosisHypovolemiaSevere refractory hypoxiaSevere pulmonary HTNCoronary disease
Restrictive Pattern
Intrapulmonary:
Intra-alveolar filling processes
Alterations in lung interstitium
Extrapulmonary
Pleural disease
Chest wall abnormalities
Neuromuscular disease