Mixed venous blood gas sampling is not influenced by the speed of withdrawal in cardiac surgery patients.
OBJECTIVE
To determine whether mixed venous blood gas sampling obtained by pulmonary artery catheter (PAC) is influenced by the speed of withdrawal.


METHODS
Prospective, observational study.


METHODS
Surgical intensive care unit at a university hospital.


METHODS
Twenty-five patients in the early postoperative period of cardiac surgery.


RESULTS
After verification of the adequate position of the PAC, measurements of mixed venous blood gas oxygen saturation, oxygen partial pressure (PO(2)), carbon dioxide partial pressure (PCO(2)), pH and bicarbonates were obtained at two different rates of withdrawal. A slow sampling was taken at a mean speed of 3 ml/min and a fast sampling at 18 ml/min for each patient. The mean difference in venous oxygen saturation between slow and fast samplings was -0.18+/-1.3%, venous PO(2): -0.2+/-1.3 mmHg, venous PCO(2): 0.1+/-0.9 mmHg, venous pH: 0+/-0.03, venous bicarbonates: 0.03+/-0.5 mmol/l.


CONCLUSIONS
Using the Bland & Altman method, we showed a satisfactory agreement between slow and fast mixed venous blood gas sampling techniques when measuring PO(2), oxygen saturation, PCO(2), pH and bicarbonates though a PAC.
Department of Medicine, CHUM (Notre-Dame Hospital), 1560 Sherbrooke East, Montreal, Quebec H2L 4M1, Canada.
Emmanuel
E
Sirdar
Jean-Gilles
JG
Guimond
Isabelle
I
Coiteux
Sylvain
S
Bélisle
Denis
D
Babin
Marie-Claude
MC
Guertin
André
A
Denault
D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis / Q000379:methods*; D002407:Catheterization, Swan-Ganz / Q000379:methods*; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D013903:Thoracic Surgery; D013997:Time Factors; D014680:Veins