Reversibility of lung collapse and hypoxemia in early acute respiratory distress syndrome.
BACKGROUND
The hypothesis that lung collapse is detrimental during the acute respiratory distress syndrome is still debatable. One of the difficulties is the lack of an efficient maneuver to minimize it.


OBJECTIVE
To test if a bedside recruitment strategy, capable of reversing hypoxemia and collapse in > 95% of lung units, is clinically applicable in early acute respiratory distress syndrome.


METHODS
Prospective assessment of a stepwise maximum-recruitment strategy using multislice computed tomography and continuous blood-gas hemodynamic monitoring.


RESULTS
Twenty-six patients received sequential increments in inspiratory airway pressures, in 5 cm H(2)O steps, until the detection of Pa(O(2)) + Pa(CO(2)) >or= 400 mm Hg. Whenever this primary target was not met, despite inspiratory pressures reaching 60 cm H(2)O, the maneuver was considered incomplete. If there was hemodynamic deterioration or barotrauma, the maneuver was to be interrupted. Late assessment of recruitment efficacy was performed by computed tomography (9 patients) or by online continuous monitoring in the intensive care unit (15 patients) up to 6 h. It was possible to open the lung and to keep the lung open in the majority (24/26) of patients, at the expense of transient hemodynamic effects and hypercapnia but without major clinical consequences. No barotrauma directly associated with the maneuver was detected. There was a strong and inverse relationship between arterial oxygenation and percentage of collapsed lung mass (R = - 0.91; p < 0.0001).


CONCLUSIONS
It is often possible to reverse hypoxemia and fully recruit the lung in early acute respiratory distress syndrome. Due to transient side effects, the required maneuver still awaits further evaluation before routine clinical application.
Borges
João B
JB
Respiratory Intensive Care Unit, Pulmonary Department, and General Intensive Care Unit, Emergency Clinics Division, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil.
Okamoto
Valdelis N
VN
Matos
Gustavo F J
GF
Caramez
Maria P R
MP
Arantes
Paula R
PR
Barros
Fabio
F
Souza
Ciro E
CE
Victorino
Josué A
JA
Kacmarek
Robert M
RM
Barbas
Carmen S V
CS
Carvalho
Carlos R R
CR
Amato
Marcelo B P
MB
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001469:Barotrauma / Q000209:etiology; D003422:Critical Care / Q000379:methods*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000628:therapy*; D055370:Lung Injury; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration / Q000009:adverse effects*; D001261:Pulmonary Atelectasis / Q000209:etiology / Q000628:therapy*; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000150:complications / Q000401:mortality / Q000628:therapy*; D014057:Tomography, X-Ray Computed
D010100:Oxygen