What are the recommended newer modes of mechanical ventilation (MV) for patients with various respiratory conditions, including Acute Respiratory Distress Syndrome (ARDS) and Chronic Obstructive Pulmonary Disease (COPD)?

Newer Modes of Mechanical Ventilation

Newer modes of mechanical ventilation such as pressure-controlled ventilation, airway pressure release ventilation, and neurally adjusted ventilatory assist (NAVA) may be considered in select patients requiring high levels of ventilatory support, but no data currently support improved mortality or morbidity outcomes compared to conventional volume-cycled ventilation. 1

Evidence-Based Recommendations for Standard Practice

Primary Ventilation Strategy

• Low tidal volume ventilation (6-8 ml/kg predicted body weight) remains the cornerstone of lung-protective ventilation and should be prioritized over any newer mode. 1, 2
• Volume-cycled ventilation using assist-control mode is appropriate at the outset of mechanical ventilation for patients with sepsis-related respiratory failure or ARDS, as no mode has been proven superior in terms of outcomes. 1
• Plateau pressure must be maintained strictly below 30 cmH2O regardless of ventilation mode to prevent barotrauma and ventilator-induced lung injury. 3, 2

PEEP Application

• Application of PEEP (minimum 5 cmH2O) is appropriate and may provide dramatic improvements in PaO2 by ameliorating changes in closing volume and lung derecruitment. 1, 2
• For COPD patients specifically, PEEP should be set at 4-8 cmH2O to offset intrinsic PEEP and improve triggering, but never higher than measured intrinsic PEEP. 3, 4, 2

Newer Modes: Limited Role

Pressure-Controlled and Airway Pressure Release Ventilation

• Pressure-controlled ventilation or airway pressure release ventilation may play a role in select patients requiring high levels of ventilatory support, although no data support improved outcomes at this time. 1
• These modes are potentially confusing to unfamiliar physicians, making them less than desirable to recommend broadly. 1
• Early airway pressure release ventilation should be considered only in certain COPD patients who remain difficult to ventilate after 12 hours of ventilator optimization. 3

High-Frequency Oscillatory Ventilation

• High-frequency or oscillatory ventilation has been tested in adults with ARDS and not shown to be of any significant benefit. 1
• Ongoing trials are attempting to determine whether certain patient subgroups may benefit from such modes, but current evidence does not support routine use. 1

Neurally Adjusted Ventilatory Assist (NAVA)

• NAVA uses the electrical activity of the diaphragm (EAdi) to trigger ventilator breaths and adjust ventilatory assist to neural drive, potentially improving patient-ventilator synchrony. 5, 6
• While NAVA demonstrates superior patient-ventilator synchrony in experimental and clinical studies, little evidence proves superiority on clinically relevant endpoints such as mortality, duration of mechanical ventilation, or ICU length of stay. 5
• In a randomized crossover trial of ARDS patients, NAVA was feasible for maintaining protective tidal volumes in only 75% of patients, with 25% requiring protocol interruption due to inability to maintain VT below 6.5 ml/kg. 7
• Patient populations with major patient-ventilator asynchrony (such as COPD patients and small children) may potentially benefit from NAVA, though definitive outcome data are lacking. 5

Proven Adjunctive Therapies Over Newer Modes

For Severe ARDS (PaO2/FiO2 < 150 mmHg)

• Prone positioning for >12 hours/day is strongly recommended and has proven mortality benefit in severe ARDS (PaO2/FiO2 <100). 1, 2
• Prone positioning is safe and results in improvements in oxygenation in approximately 65% of patients with ALI/ARDS. 1
• Neuromuscular blocking agents should be considered in severe cases. 1

Simple, Readily Available Therapies

• Inhaled beta-agonists reduce inspiratory pressure and increase lung compliance by reducing airway resistance, though without significant benefits in overall outcome. 1
• Elevating the head of the bed at least 30 degrees at all times reduces the incidence of gastric material migrating to the trachea. 1
• Specific enteral nutritional formulae with antioxidants and amino acid compositions designed to reduce inflammatory lipid mediators have been demonstrated to improve gas exchange and reduce the duration of mechanical ventilation and ICU stay in ARDS patients. 1

Critical Pitfalls to Avoid

• Do not abandon low tidal volume ventilation in favor of newer modes—lung-protective ventilation with 6-8 ml/kg predicted body weight remains the only ventilation strategy with proven mortality benefit. 1, 2
• Avoid implementing newer modes that are unfamiliar to the clinical team, as this introduces risk of mismanagement without proven benefit. 1
• Do not delay proven interventions (prone positioning, neuromuscular blockade in severe ARDS) while attempting newer ventilation modes. 1
• For COPD patients, ensure adequate expiratory time with I:E ratio of 1:2 to 1:4 regardless of mode to prevent air trapping and auto-PEEP. 3, 4, 2

Disease-Specific Considerations

ARDS Management

• Noninvasive support with close monitoring is a reasonable initial approach in less severely ill patients with ARDS. 1
• PEEP selection should be based on gas exchange, hemodynamic status, lung recruitability, end-expiratory transpulmonary pressure, and driving pressure. 1
• Consider esophageal pressure measurement to guide ventilator management in complex cases. 1

COPD-Specific Modifications

• Set respiratory rate at 10-14 breaths/min with prolonged expiratory time to prevent breath stacking and auto-PEEP. 3, 4, 2
• Accept permissive hypercapnia with pH >7.2 if hemodynamically stable to avoid excessive ventilation. 3, 2
• Target oxygen saturation of 88-92% to avoid worsening hypercapnia from excessive oxygen administration. 3, 4, 2
• Plan early transition to noninvasive ventilation post-extubation, as prophylactic NIV reduces reintubation risk in hypercapnic COPD patients. 4