What is mechanical ventilation (MV)?

From the Guidelines

Mechanical ventilation should be initiated in patients with respiratory failure, with a focus on lung-protective strategies, such as maintaining tidal volumes of 6-8 mL/kg of ideal body weight and plateau pressures below 30 cmH2O, as recommended by the American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline 1.

Key Considerations

• The primary indications for mechanical ventilation include respiratory failure, airway protection, respiratory muscle fatigue, and to reduce the work of breathing.
• Initial ventilator settings should include a tidal volume of 6-8 mL/kg of ideal body weight, respiratory rate of 12-20 breaths per minute, PEEP of 5-10 cmH2O, and FiO2 starting at 100% and titrated down based on oxygen saturation goals.
• Sedation is often required using medications like propofol, midazolam, or dexmedetomidine.
• Lung-protective strategies are essential to prevent ventilator-induced lung injury, particularly maintaining plateau pressures below 30 cmH2O.
• Regular assessment of readiness for extubation should be performed using spontaneous breathing trials.

Ventilator Modes

• Volume-controlled ventilation (VCV) is a common mode of ventilation, which delivers a set tidal volume with each breath.
• Pressure-controlled ventilation (PCV) is another mode, which delivers a set inspiratory pressure with each breath.
• Pressure support ventilation (PSV) is a mode that provides a set level of pressure support with each spontaneous breath.

Complications

• Ventilator-associated pneumonia is a common complication of mechanical ventilation.
• Barotrauma and volutrauma are also potential complications, which can be prevented by maintaining plateau pressures below 30 cmH2O.
• Oxygen toxicity is another potential complication, which can be prevented by titrating FiO2 down based on oxygen saturation goals.

Liberation from Mechanical Ventilation

• Regular assessment of readiness for extubation should be performed using spontaneous breathing trials.
• Patients who pass the spontaneous breathing trial should be extubated as soon as clinically appropriate.
• The use of noninvasive positive-pressure ventilation (NIPPV) has not been shown to be effective in reducing the incidence of respiratory failure in sepsis or its attributable mortality 1.

From the Research

Mechanical Ventilation Strategies

• The mainstay of treatment for Acute Respiratory Distress Syndrome (ARDS) includes a lung protective ventilation strategy with low tidal volumes (4-8 mL/kg predicted body weight), adequate positive end-expiratory pressure (PEEP), and maintaining a plateau pressure of < 30 cm H2O 2.
• Current management of COVID-19 related respiratory failure requiring invasive mechanical ventilation should focus on supportive care, preventing further lung injury from mechanical ventilation, and treating the underlying cause 2.

Sedation and Analgesia in Mechanical Ventilation

• Current ICU analgesia/sedation guidelines promote analgesia first and minimization of sedation, wakefulness, delirium prevention and early rehabilitation to facilitate ventilator and ICU liberation 3, 4.
• Deep sedation, especially early in the course of mechanical ventilation, is associated with prolonged time to liberation from mechanical ventilation, longer ICU stays, longer hospital stays, and increased mortality 4.
• Dexmedetomidine may prevent ICU delirium when administered nocturnally at low doses, and can reduce the duration of mechanical ventilation compared to midazolam 5.

Comparison of Sedatives in Mechanical Ventilation

• Dexmedetomidine was not inferior to midazolam and propofol in maintaining light to moderate sedation in ICU patients receiving prolonged mechanical ventilation 5.
• Propofol and midazolam are frequently given by continuous infusion for sedation in critically ill, mechanically ventilated patients, with propofol having a faster and more reliable wake-up time 6.
• The choice of sedative should be based on the individual patient's needs and medical history, with consideration of the potential benefits and risks of each medication 5, 6.