https://pubmed.ncbi.nlm.nih.gov/27626833/

Notes

1. Mechanical ventilation and ventilator-induced lung injury:
   • Mechanical ventilation is used to sustain life in patients with acute respiratory failure, but it carries the risk of ventilator-induced lung injury (VILI).
   • Lung-protective ventilation has been shown to reduce the risk of VILI in patients with acute respiratory distress syndrome (ARDS).
2. Extending the concept of VILI:
   • Patients with hypoxemic respiratory failure who have high respiratory drive may also be at risk of lung injury, even if they are not intubated or ventilated.
   • Lung-protective ventilation could be considered as a prophylactic therapy to mitigate patient self-inflicted lung injury (P-SILI).
3. Interactions between ventilation and lung disease:
   • Understanding the forces applied to the lungs and the resulting deformation is essential for recognizing and reducing VILI.
   • Monitoring driving pressure, a physiologically sound approach, can help set ventilation strategy in patients with ARDS.
4. Spontaneous breathing during MV:
   • Spontaneous ventilation during mechanical ventilation for ARDS can worsen lung injury.
   • Use of neuromuscular blocking agents has been shown to decrease biotrauma and improve outcomes.
   • Spontaneous breathing may cause more injury in lungs with pre-existing injury compared to controlled mechanical ventilation.
5. Lung injury in nonintubated patients:
   • Noninvasive ventilation (NIV) has limited success in patients with hypoxemic respiratory failure, and large tidal volumes may contribute to failure of NIV.
   • Increased tidal volumes and ventilation in nonintubated patients may cause lung injury similar to VILI.
   • Therapies that minimize generation of large tidal volumes should be considered as prophylactic therapy to avoid the progression of lung injury.
6. Reducing dead space and ventilatory need:
   • The ratio of dead space to tidal volume is a strong indicator of ARDS severity.
   • Nasal delivery of heated and humidified oxygen at high flow rates can potentially reduce physiological dead space and ventilatory need.
7. Challenges in evidence-gathering:
   • Recognition of lung injury caused by mechanical ventilation took a long time, and similar challenges exist in nonintubated patients.
   • Limited monitoring of ventilatory variables in nonintubated patients makes assessment more difficult.
8. ILI (23).MV as a Necessary Protection:
   • Spontaneously breathing patients with high respiratory drive should minimize P-SILI.
   • Intubation and a lung-protective ventilatory strategy can achieve this goal.
9. Applying the Concepts:
   • Understanding basic physiological concepts can help clinicians prevent severe lung injury and ARDS.
   • Greater implementation of lung protection is needed for both intubated and nonintubated patients.

Abstract

Mechanical ventilation is used to sustain life in patients with acute respiratory failure. A major concern in mechanically ventilated patients is the risk of ventilator-induced lung injury, which is partially prevented by lung-protective ventilation. Spontaneously breathing, nonintubated patients with acute respiratory failure may have a high respiratory drive and breathe with large tidal volumes and potentially injurious transpulmonary pressure swings. In patients with existing lung injury, regional forces generated by the respiratory muscles may lead to injurious effects on a regional level. In addition, the increase in transmural pulmonary vascular pressure swings caused by inspiratory effort may worsen vascular leakage. Recent data suggest that these patients may develop lung injury that is similar to the ventilator-induced lung injury observed in mechanically ventilated patients. As such, we argue that application of a lung-protective ventilation, today best applied with sedation and endotracheal intubation, might be considered a prophylactic therapy, rather than just a supportive therapy, to minimize the progression of lung injury from a form of patient self-inflicted lung injury. This has important implications for the management of these patients.

Keywords: gas exchange; hyperventilation; noninvasive ventilation; ventilator-induced lung injury.

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