CARBON-DIOXIDE REBREATHING METHOD OF CARDIAC-OUTPUT MEASUREMENT DURING ACUTE RESPIRATORY-FAILURE IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE
R. Neviere et al., CARBON-DIOXIDE REBREATHING METHOD OF CARDIAC-OUTPUT MEASUREMENT DURING ACUTE RESPIRATORY-FAILURE IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE, Critical care medicine, 22(1), 1994, pp. 81-85
Objective: To compare measurement of cardiac output by the CO2 rebreat
hing method vs. the thermodilution cardiac output technique in the set
ting of acute respiratory failure in patients with chronic obstructive
pulmonary disease. Design: Prospective, comparative study of two meth
ods in a consecutive sample.Setting: Intensive care unit. Patients: Tw
enty-five patients with chronic obstructive pulmonary disease with acu
te respiratory failure were studied. The patients were being mechanica
lly ventilated and monitored with systemic and pulmonary artery cathet
ers. Measurements and Main Results: Cardiac output was determined, usi
ng both the thermodilution technique and an indirect CO2 Fick method.
Veno-arterial CO2 content difference was calculated from an estimated
mixed venous PcO(2), obtained by an equilibrium CO2 rebreathing method
and measured PaCO2, PCO2, was converted to content using the equation
of the CO2 dissociation curve described by McHardy. A wide range of c
ardiac output was studied. There was a significant correlation between
thermodilution and CO2 rebreathing methods (r(2) = .92, p < .001). Th
e mean difference between thermodilution and CO2 rebreathing methods w
as -0.06 L/min/m(2), standard deviation for the bias was 0.028 L/min/m
(2), and 95% confidence interval for the bias was -0.120 to -0.001 L/m
in/m(2). Conclusion: Our results suggest that the CO2 rebreathing meth
od may be a reliable noninvasive technique to determine cardiac output
in mechanically ventilated patients with chronic obstructive pulmonar
y disease.