Does alveolar recruitment occur with positive end-expiratory pressure in adult respiratory distress syndrome patients?

• Published in: Journal of critical care Vol. 8; no. 1; pp. 34 - 42
• Main Authors: Valta, Päivi, Takala, Jukka, Eissa, N.Tony, Milic-Emili, Joseph
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier Inc 01.03.1993; Elsevier
• Subjects: Adult; Aged; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Carbon Dioxide - blood; Emergency and intensive respiratory care; Female; Humans; Intensive care medicine; Lung Compliance; Lung Volume Measurements; Male; Medical sciences; Middle Aged; Oxygen - blood; Plethysmography; Positive-Pressure Respiration; Pulmonary Alveoli - physiopathology; Respiratory Distress Syndrome, Adult - physiopathology; Respiratory Distress Syndrome, Adult - therapy; Tidal Volume; Human; Positive end expiratory pressure; Lung function; Respiratory disease; Respiratory intensive care; Adult; Respiratory distress; Artificial ventilation
• ISSN: 0883-9441; 1557-8615
• DOI: 10.1016/0883-9441(93)90031-F

We studied the effects of positive end-expiratory pressure (PEEP) (2 to 14 cm H 2O) on alveolar recruitment (Vrec), static respiratory compliance, and end-expiratory lung volume (EELV) in nine sedated, paralyzed, mechanically ventilated adult respiratory distress syndrome patients. Positive end-expiratory pressure was applied in increasing and decreasing steps of 2 cm H 2O. Flow, tidal volume, and airway pressure were measured. We used the rapid airway occlusion technique to determine static end-inspiratory elastic recoil pressure of the respiratory system (Pst, rs) and intrinsic PEEP (PEEPi). The changes in EELV were measured with respiratory inductive plethysmography. Alveolar recruitment was estimated as the difference in lung volume between PEEP and zero end-expiratory pressure (ZEEP) for the same end-inspiratory Pst,rs (20 cm H 2O). We found that (1) Vrec with PEEP up to 14 cm H 2O was in general rather small and was absent in two patients; (2) all patients exhibited PEEN at ZEEP (5.6 ± 1.0 cm H 2O) and little change in EELV and Vrec was achieved until the external PEEP exceeded PEEPi; (3) if end-inspiratory Pst, rs is high at ZEEP, there is little or no alveolar recruitment with PEEP; and (4) Vrec and EELV were slightly higher during stepwise deflation than stepwise inflation with PEEP, except at ZEEP where EELV did not change after inflation-deflation runs with PEEP.