Drainage of pleural effusion in mechanically ventilated patients: Time to measure chest wall compliance?

Abstract

PurposePleural effusion (PE) is commonly encountered in mechanically ventilated, critically ill patients and is generally addressed with evacuation or by fluid displacement using increased airway pressure (PAW). However, except when massive or infected, clear evidence is lacking to guide its management. The aim of this study was to investigate the effect of recruitment maneuvers and drainage of unilateral PE on respiratory mechanics, gas exchange, and lung volume. Materials and methodsFifteen critically ill and mechanically ventilated patients with unilateral PE were enrolled. A 3-step protocol (baseline, recruitment, and effusion drainage) was applied to patients with more than 400 mL of PE, as estimated by chest ultrasound. Predefined subgroup analysis compared patients with normal vs reduced chest wall compliance (CCW). Esophageal and PAWs, respiratory system, lung and CCWs, arterial blood gases, and end-expiratory lung volumes were recorded. ResultsIn the whole case mix, neither recruitment nor drainage improved gas exchange, lung volume, or tidal mechanics. When CCW was normal, recruitment improved lung compliance (81.9 [64.8-104.1] vs 103.7 [91.5-111.7] mL/cm H2O, P < .05), whereas drainage had no significant effect on total respiratory system mechanics or gas exchange, although it measurably increased lung volume (1717 vs 2150 mL, P < .05). In the setting of reduced CCW, however, recruitment had no significant effect on total respiratory system mechanics or gas exchange, whereas pleural drainage improved respiratory system and CCWs as well as lung volume (42.7 [38.9-50.0] vs 47.0 [43.8-63.3], P < .05 and 97.4 [89.3-97.9] vs 126.7 [92.3-153.8] mL/cm H2O, P < .05 and 1580 vs 1750 mL, P < .05, respectively). ConclusionsDrainage of a moderate-sized effusion should not be routinely performed in unselected population of critically ill patients. We suggest that measurement of CCW may help in the decision-making process.