Non-invasive determination of effective pulmonary blood flow: evaluation of a simplified rebreathing method.
OBJECTIVE
To evaluate a new technical approach to measuring effective pulmonary blood flow (PBF) in mechanically ventilated patients.


METHODS
Prospective clinical study; evaluation of accuracy and reproducibility.


METHODS
Effective pulmonary blood flow was determined non-invasively in 32 mechanically ventilated patients by using a new rebreathing system (PBF(rb)). Cardiac output corrected for intrapulmonary shunt was taken as reference value (PBF(thd)). Bias, precision and reproducibility of the rebreathing method were calculated from duplicate measurements in each patient.


RESULTS
The mean difference between PBF(rb) and PBF(thd) was - 0.67 +/- 0.83 l min(-1). The mean difference between duplicate measurements with the rebreathing system was 0.16 +/- 0.36 l min(-1). However, the accuracy of the rebreathing system tended to decrease in patients with PBF levels greater than 6 l min(-1).


CONCLUSIONS
The new device appears to be reliable for determination of PBF values below 6 l min(-1). With this limitation, the present method may be used as a trend-indicator of PBF in mechanically ventilated patients.
Reutershan
J
J
Department of Anaesthesiology and Intensive Care, University Hospital of Tübingen, Germany. joerg.reutershan@med.uni-tuebingen.de
Ressel
M
M
Wagner
T
T
Schröder
T
T
Dietz
K
K
Fretschner
R
R
D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002302:Cardiac Output; D003422:Critical Care / Q000379:methods; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000503:physiopathology; D008168:Lung / Q000098:blood supply* / Q000503:physiopathology*; D008171:Lung Diseases / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011652:Pulmonary Circulation; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D012119:Respiration; D012121:Respiration, Artificial; D012129:Respiratory Function Tests / Q000295:instrumentation* / Q000379:methods*; D012680:Sensitivity and Specificity