Assessment of PEEP-induced reopening of collapsed lung regions in acute lung injury: are one or three CT sections representative of the entire lung?
OBJECTIVE
To study whether PEEP-induced reopening of collapsed lung regions--defined as the decrease in nonaerated lung volume measured on a single or three computerized tomographic (CT) sections--is representative of the decrease in overall nonaerated lung volume.


METHODS
Review of 39 CT scans obtained in consecutive patients with Acute Lung Injury.


METHODS
Fourteen-bed surgical intensive care unit of a University Hospital.


RESULTS
PEEP-induced decrease in nonaerated lung volume was measured in 39 patients with ALI on a single juxtadiaphragmatic CT section, on three CT sections--apical, hilar, and juxtadiaphragmatic--and on contiguous apex-to-diaphragm CT sections. The percentage of decrease in nonaerated lung volume following PEEP, was compared between one, three and all CT sections using a linear regression analysis and Bland and Altman's method. The decrease in nonaerated lung volume measured on a single and three CT sections was significantly correlated with the decrease in nonaerated lung volume measured on all CT sections: R=0.83, P<0.0001 for one CT section and R=0.92, P<0.0001 for three CT sections. However, measurements performed on a single CT section were poorly representative of the overall lung: bias -6%, limits of agreement ranging between -37% and +25%. Measurements performed on three CT sections overestimated by 11% the overall decrease in nonaerated lung volume: bias -11%, limits of agreement ranging between -29% and +7%.


CONCLUSIONS
PEEP-induced reopening of collapsed lung regions measured on a single or three CT sections sensibly differs from the reopening of collapsed lung regions measured on the overall lung. The inhomogeneous distribution of PEEP-induced reopening of collapsed lung regions along the cephalocaudal axis probably explains these discrepancies.
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Réanimation Chirurgicale Pierre Viars, Department of Anesthesiology, La Pitié-Salpêtrière Hospital, 47-83, Boulevard de l'Hôpital, 75013 Paris, France.
Malbouisson
L M
LM
Mourgeon
E
E
Goldstein
I
I
Coriat
P
P
Rouby
J J
JJ
D000328:Adult; D000368:Aged; D015982:Bias; D015986:Confounding Factors, Epidemiologic; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D016014:Linear Models; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D011652:Pulmonary Circulation; D012123:Pulmonary Ventilation; D012128:Respiratory Distress Syndrome / Q000145:classification / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards*; D014655:Vascular Resistance