Do periodic hyperinflations improve gas exchange in patients with hypoxemic respiratory failure?

Prolonged artificial ventilation may result in worsening gas exchange and pulmonary compliance in patients with otherwise normal lungs. Prolonged hyperinflations to 40 cm H2O can completely reverse deterioration of gas exchange and compliance in such patients. Similar efforts have effectively recruited atelectatic lung regions in critically ill patients. Less aggressive hyperinflations have not improved lung function in patients with abnormal lungs with hypoxemia. However, sustained exaggerated hyperinflations may successfully open collapsed lung units in these patients when standard recruitment techniques fail. We compared periodic hyperinflations of 40 cm H2O lasting 15 to 30 sec associated with body positioning (directed recruitment [DR]) to standard bag-sigh-suctioning (BSS) for their effects on gas exchange and pulmonary compliance in 16 stable surgical ICU patients with hypoxemic respiratory failure of 24-h duration or longer. Patients were sequentially alternated between DR and BSS (group 1, BSS followed by DR; group 2, DR followed by BSS). Neither technique, alone or in sequence, resulted in a sustained (greater than or equal to 5 min) improvement or deterioration in either gas exchange or pulmonary compliance. We conclude that neither BSS nor DR reliably affects gas exchange or compliance in patients with established hypoxemic respiratory failure.