Prone-position ventilation induces sustained improvement in oxygenation in patients with acute respiratory distress syndrome who have a large shunt.
OBJECTIVE
Prone-position ventilation (PPV) induces acute improvement in oxygenation in many patients with acute respiratory distress syndrome (ARDS), with some maintaining their oxygenation even after they were returned to the supine position, but it is unclear what clinical factors determine the sustained oxygenation benefit. We hypothesized that patients with ARDS who have a larger shunt would have a better acute and sustained oxygenation response to PPV.


METHODS
Prospective, nonrandomized interventional study.


METHODS
Medical and surgical intensive care units, university tertiary care center.


METHODS
Twenty-two consecutive patients, with ARDS with an average PaO2/FiO2 of 94, were administered PPV for 12 hrs followed by supine-position ventilation for 2 hrs.


METHODS
Hemodynamic and gas exchange variables were monitored. The shunt was measured as venous admixture at an FiO2 of 1.0, and compliances of the respiratory system, lung, and chest wall were measured by the esophageal balloon technique before PPV, during PPV, and during subsequent supine-position ventilation.


RESULTS
Fourteen patients (64%) responded to PPV, with PaO2/FiO2 increasing by > or =20. These changes were associated with a decrease in chest wall compliance. Responders had significantly shorter time from ARDS to PPV, a lower baseline PaO2/FiO2, and a higher venous admixture. All responders maintained the improvement in oxygenation and had a greater respiratory system compliance after returning to the supine position. Time from ARDS to PPV and baseline lung injury score were negatively associated, whereas chest wall compliance, heart rate, and PaCO2 were positively associated with sustained improvement in oxygenation.


CONCLUSIONS
PPV induced acute and sustained improvement in oxygenation in many patients with ARDS. The sustained improvement is more significant if PPV is administered early to patients with a larger shunt and a more compliant chest wall. Measuring venous admixture and chest wall compliance before PPV may help select a subgroup of patients with ARDS who may benefit the most from PPV.
Lee
David Lin
DL
Department of Medicine, Kaohsiung Veterans General Hospital, Kaohsiung City, Taiwan, Republic of China.
Chiang
Hung-Ting
HT
Lin
Shoa-Lin
SL
Ger
Luo-Ping
LP
Kun
Ming-Ho
MH
Huang
Yuh-Chin T
YC
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D016684:Prone Position; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D012128:Respiratory Distress Syndrome / Q000378:metabolism* / Q000628:therapy*
D010100:Oxygen