What are the guidelines for initiating and managing mechanical ventilation (MV) in patients with respiratory failure?

Mechanical Ventilation in Respiratory Failure

Mechanical ventilation should be initiated in patients with respiratory failure based on clinical criteria including airway obstruction, altered consciousness (GCS ≤ 8), hypoventilation, or hypoxemia (PaO₂ < 60 mmHg despite high-flow oxygen) to prevent further deterioration and reduce mortality. 1

Indications for Mechanical Ventilation

• Respiratory failure characterized by hypoxemia (PaO₂ < 60 mmHg despite high-flow oxygen) or hypoventilation (PaCO₂ > 50 mmHg with pH < 7.35) 1
• Airway protection in patients with altered consciousness (Glasgow Coma Scale ≤ 8) 1
• High respiratory rate (> 35 breaths/min) and low vital capacity (< 15 ml/kg) 1
• Excessive work of breathing that may lead to respiratory muscle fatigue 2

Types of Mechanical Ventilation

Non-Invasive Ventilation (NIV)

• Should be considered first in patients with dyspnea and/or persistent hypoxemia despite oxygen therapy when medical staff is adequately trained 2
• Continuous Positive Airway Pressure (CPAP) improves oxygenation, decreases symptoms of acute heart failure, and reduces need for endotracheal intubation 2
• Non-invasive Positive Pressure Ventilation (NIPPV) decreases the need for endotracheal intubation in cardiogenic pulmonary edema 2
• Contraindicated in patients with impaired consciousness, severe respiratory or cardiovascular failure 2

Invasive Mechanical Ventilation

• Requires endotracheal intubation or tracheostomy 2
• Indicated when non-invasive methods fail or are contraindicated 2
• Should not be used to reverse hypoxemia that could be better managed with oxygen therapy, CPAP, or NIPPV 2

Ventilation Strategies

Lung-Protective Ventilation

• Use lower tidal volumes (4-8 ml/kg predicted body weight) and lower inspiratory pressures (plateau pressure ≤ 30 cmH₂O) in patients with ARDS 2
• Keep positive end-expiratory pressure (PEEP) applied with caution to limit adverse hemodynamic effects 2
• Use low tidal volumes (approximately 6 ml/kg lean body weight) to keep end-inspiratory plateau pressure below 30 cmH₂O 2

Positioning

• Prone positioning for more than 12 hours per day is strongly recommended for patients with severe ARDS 2
• Semi-recumbent position (head of bed raised to 30-45°) reduces risk of tracheal aspiration and hospital-acquired pneumonia 2
• Unconscious patients should be placed in lateral position to keep airway clear 2

Advanced Strategies for Refractory Cases

• Higher PEEP in patients with moderate or severe ARDS 2
• Recruitment maneuvers in patients with moderate or severe ARDS 2
• Venovenous extracorporeal membrane oxygenation (VV-ECMO) for patients with PaO₂/FiO₂ < 80 or pH < 7.25 with PCO₂ > 60 2
• Avoid routine use of high-frequency oscillatory ventilation in moderate or severe ARDS 2

Monitoring During Mechanical Ventilation

• Monitor oxygenation with pulse oximetry, targeting saturation of approximately 90% (PaO₂ around 60 mmHg) 1
• Use capnography to ensure appropriate ventilation 3
• Assess driving pressure, transpulmonary pressure, and pressure-volume loops to ensure adequate PEEP and minimize excess distending pressure 3
• Monitor airway cuff pressures to minimize risk of airway injury and ventilator-associated pneumonia 3
• For ICU sedation in mechanically ventilated patients, propofol should be initiated slowly with continuous infusion (5-50 mcg/kg/min) to minimize hypotension 4

Potential Complications and Mitigation Strategies

• Ventilator-induced lung injury (VILI): Minimize by using lung-protective ventilation strategies 5
• Hemodynamic compromise: May affect cardiovascular performance, cerebral perfusion pressure, and renal function 6
• Patient self-inflicted lung injury (P-SILI): Can occur in spontaneously breathing patients with high respiratory drive 5
• Ventilator-associated pneumonia: Reduce risk with proper positioning and airway management 3
• Ventilator-induced diaphragm dysfunction: Avoid through appropriate ventilator settings and weaning protocols 7

Special Considerations

• In patients with idiopathic pulmonary fibrosis (IPF) and respiratory failure, mechanical ventilation is generally not recommended due to high mortality (87-96%) 2
• Mechanical ventilation in IPF should only be used after discussion with patients and caregivers regarding goals of care 2
• In rare circumstances, mechanical ventilation may be appropriate as a bridge to lung transplantation in IPF patients 2
• Abrupt discontinuation of sedation in mechanically ventilated patients should be avoided to prevent anxiety, agitation, and resistance to mechanical ventilation 4

Weaning from Mechanical Ventilation

• Evaluate level of sedation and assess CNS function daily to determine minimum dose of sedatives required 4
• Infusions of sedatives should be adjusted to maintain minimal level of sedation throughout the weaning process 4
• Personalize mechanical ventilation based on individual physiological characteristics and responses to therapy 7