What are the appropriate ventilator settings?

From the Guidelines

Ventilator settings should be individualized based on the patient's condition, but generally start with 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 of 40-60% to maintain oxygen saturation above 92%. For patients with ARDS, use lung-protective ventilation with lower tidal volumes (4-6 mL/kg) and higher PEEP (10-15 cmH2O) as recommended by the American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline 1. Initial mode selection typically includes volume-controlled ventilation for stable patients or pressure-controlled for those with compliance issues.

Key Considerations

• Adjust settings based on arterial blood gases, targeting a pH of 7.35-7.45 and PaCO2 of 35-45 mmHg.
• Monitor plateau pressures, keeping them below 30 cmH2O to prevent barotrauma, as suggested by the international expert panel-based consensus recommendations 1.
• Sedation with medications like propofol (5-50 mcg/kg/min) or midazolam (1-5 mg/hr) may be necessary, along with pain control.
• Position the patient with the head of bed elevated 30 degrees (i.e., ‘beach chair’) before induction of anesthesia to prevent atelectasis and improve respiratory function 1.
• Use non-invasive positive-pressure ventilation (NIPPV) or continuous positive airway pressure (CPAP) before the loss of spontaneous ventilation to attenuate anesthesia-induced respiratory changes, if not contraindicated 1.

Additional Recommendations

• The ventilator should initially be set to deliver a tidal volume of 6-8 ml/kg of predicted body weight and PEEP of 5 cm H2O, with zero end-expiratory pressure (ZEEP) not recommended 1.
• Appropriate PEEP and recruitment maneuvers may improve intraoperative respiratory function and prevent postoperative pulmonary complications (PPCs) 1.
• Dynamic compliance, driving pressure (Pplate-PEEP), and Pplat should be monitored on all controlled mechanically ventilated patients, in addition to standard monitoring (ASA/ESA) 1.

From the Research

Ventilator Settings

The appropriate ventilator settings for critically ill patients can be determined based on several studies.

• Tidal volume: 4 to 8 mL/kg of predicted body weight 2, 3, 4, 5
• Positive end-expiratory pressure (PEEP): ≥5 cm H2O 6, 2, 3, 4, 5
• Peak or plateau pressure: ≤30 cm H2O 6, 2, 4, 5
• Respiratory rate: 20 to 35 breaths per minute 2
• Fraction of inspired oxygen (FiO2): titrated to maintain peripheral oxygen saturation (SpO2) levels of 88 to 95% 2, 5

Lung Protective Ventilation

Lung protective ventilation is recommended as an initial approach to mechanical ventilation in both perioperative and critical care settings 2.

• Prevention of volutrauma: tidal volume 4 to 8 mL/kg of predicted body weight with plateau pressure <30 cmH2O 2
• Prevention of atelectasis: PEEP ≥5 cmH2O, as needed recruitment maneuvers 2
• Adequate ventilation: respiratory rate 20 to 35 breaths per minute 2
• Prevention of hyperoxia: titrate FiO2 to SpO2 levels of 88 to 95% 2

Specific Patient Populations

For patients with COVID-19 acute respiratory distress syndrome (ARDS), closed-loop mechanical ventilation may be associated with a higher degree of lung-protective ventilation than conventional mechanical ventilation 5. For patients with severe and persistent ARDS, a ventilatory strategy based on PEEP above the lower inflection point of the pressure volume curve of the respiratory system set on day 1 with a low tidal volume may result in improved outcome 4.