Effect of alveolar recruitment maneuver in early acute respiratory distress syndrome according to antiderecruitment strategy, etiological category of diffuse lung injury, and body position of the patient.
OBJECTIVE
To assess how the level of positive end-expiratory pressure (PEEP) (antiderecruitment strategy), etiological category of diffuse lung injury, and body position of the patient modify the effect of the alveolar recruitment maneuver (ARM) in acute respiratory distress syndrome (ARDS).


METHODS
Prospective clinical trial.


METHODS
Medical intensive care unit at a tertiary hospital.


METHODS
Forty-seven patients with early ARDS, including 19 patients from our preliminary study.


METHODS
From baseline ventilation at a tidal volume of 8 mL/kg and PEEP of 10 cm H2O, the ARM (a stepwise increase in the level of PEEP up to 30 cm H2O with a concomitant decrease in the magnitude of tidal volume down to 2 mL/kg) was given with (ARM + PEEP, n = 20) or without (ARM only, n = 19) subsequent increase of PEEP to 15 cm H2O. In eight other patients, PEEP was increased to 15 cm H2O without a preceding ARM (PEEP only).


RESULTS
In all three groups, Pao2 was increased by the respective intervention (all p<.05). In the ARM-only group, Pao2 at 15 mins after intervention was lower than Pao2 immediate after intervention (p =.046). In the ARM + PEEP group, no such decrease in Pao2 was observed, and Pao2 at 15, 30, 45, and 60 mins after intervention was higher than in the ARM-only group (all p<.05). Compared with the PEEP-only group, Pao2 of the ARM + PEEP group was higher immediately after intervention and at the later time points (all p <.05). Compared with patients with ARDS associated with direct lung injury (pulmonary ARDS), patients with ARDS associated with indirect lung injury (extrapulmonary ARDS) showed a greater increase in Pao2 (27 +/- 21% vs. 130 +/- 112%; p=.002) and a greater decrease in radiologic scores (1.0 +/- 2.4 vs. 3.4 +/- 1.5; p=.005) after the ARM. The increase in Pao2 induced by the ARM was greater for patients in the supine position than for patients in the prone position (61 +/- 82% vs. 21 +/- 14%; p=.028). Consequently, Pao immediately after the ARM was similar in the two groups of patients in different positions.


CONCLUSIONS
After the ARM, a sufficient level of PEEP is required as an antiderecruitment strategy. Pulmonary ARDS and extrapulmonary ARDS may be different pathophysiologic entities. An effective ARM may obviate the need for the prone position in ARDS at least in terms of oxygenation.
Lim
Chae-Man
CM
Department of Internal Medicine, Asan Medical Center, University of Ulsan, Seoul, Korea.
Jung
Hoon
H
Koh
Younsuck
Y
Lee
Jin Seoung
JS
Shim
Tae-Sun
TS
Lee
Sang-Do
SD
Kim
Woo-Sung
WS
Kim
Dong Soon
DS
Kim
Won-Dong
WD
D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D011187:Posture; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000503:physiopathology*; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*