Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
MECHANICAL VENTILATION Seyed Alireza Mahdavi
Ventilator settings • Ventilator mode • Respiratory rate • Tidal volume or pressure settings • Inspiratory flow • I:E ratio • PEEP • FiO2 • Inspiratory trigger
Concepts and Modes of Mechanical Ventilation Spontaneous Breathing Mechanical Ventilation Pressure CMV Time SIMV Pressure Time Bivent Pressure Time APRV Pressure Time CPAP Pressure Time
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 activity • Lesions 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 hyperinflation • Diminish work of breathing • Controlled hypoventilation (permissive hypercapnia)
Diminish DHI • Why?
Diminish DHI • How? • Diminish minute ventilation • Low Vt (6-8 cc/kg) • Low RR (8-10 b/min) • Maximize expiratory time
Diminish work of breathing • How: • Add PEEP (about 85% of PEEPi) • Applicable in COPD and Asthma.
Controlled hypercapnia • Why? • Limit high airway pressures and thus diminish the risk of complications
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 pathologies • Severe HTN • Severe metabolic acidosis • Hypovolemia • Severe refractory hypoxia • Severe pulmonary HTN • Coronary disease
Restrictive Pattern • Intrapulmonary: Intra-alveolar filling processes Alterations in lung interstitium • Extrapulmonary Pleural disease Chest wall abnormalities • Neuromuscular disease
Management of Mechanical Ventilation • Volume • Pressure • I:E ratio • Mode