Screening of ARDS patients using standardized ventilator settings: influence on enrollment in a clinical trial.
OBJECTIVE
The American-European consensus conference (AECC) definition for acute respiratory distress syndrome (ARDS) requires a PaO(2)/F(I)O(2)< or =200 mmHg, regardless of ventilator settings. We report the results of using standardized ventilator settings to screen and enroll ARDS patients in a clinical trial of high-frequency oscillatory ventilation (HFOV), including the impact on study enrollment, and potential effects on study outcome.


METHODS
Prospective cohort study.


METHODS
Intensive care units in two teaching hospitals. PARTICIPANTS. A consecutive sample of 41 patients with early ARDS by AECC criteria (baseline PaO(2)/F(I)O(2)< or =200) who met all other inclusion/exclusion criteria for the HFOV trial.


METHODS
Patients were placed on standardized ventilator settings (tidal volume 7-8 ml/kg, PEEP 10 cmH(2)O, F(I)O(2) 1.0), and the PaO(2)/F(I)O(2) was reassessed after 30 min.


RESULTS
Seventeen patients (41.5%) had PaO(2)/F(I)O(2) ratios that remained < or =200 mmHg [Persistent ARDS; PaO(2)/F(I)O(2)=94+/-36 (mean+/-SD)] and went on to inclusion in the HFOV study; however, in 24 patients (58.5%) the PaO(2)/F(I)O(2) was >200 mmHg [Transient ARDS; PaO(2)/F(I)O(2)=310+/-74] and these patients were ineligible for the HFOV study. The ICU mortality was significantly greater (52.9 vs 12.5%; p=0.01) in the Persistent ARDS patients.


CONCLUSIONS
The use of these standardized ventilatory significantly impacted the PaO(2)/F(I)O(2) ratio and therefore the ARDS prevalence and trial enrollment. These results have effects on the evaluation of the current ARDS literature and conduct of clinical trials in ARDS and hence consideration should be given to the use of standardized ventilatory settings in future ARDS trials.
Ferguson
Niall D
ND
Division of Respirology, Department of Medicine, and the Interdepartmental Division of Critical Care Medicine, University Health Network and Mount Sinai Hospital, University of Toronto, Toronto, Canada. n.ferguson@utoronto.ca
Kacmarek
Robert M
RM
Chiche
Jean-Daniel
JD
Singh
Jeffrey M
JM
Hallett
David C
DC
Mehta
Sangeeta
S
Stewart
Thomas E
TE
D015982:Bias; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011446:Prospective Studies; D012015:Reference Standards; D012107:Research Design; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy