Published in:
01-10-2004 | Brief Report
Mixed venous blood gas sampling is not influenced by the speed of withdrawal in cardiac surgery patients
Published in: Intensive Care Medicine | Issue 10/2004
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Objective
To determine whether mixed venous blood gas sampling obtained by pulmonary artery catheter (PAC) is influenced by the speed of withdrawal.
Design
Prospective, observational study.
Setting
Surgical intensive care unit at a university hospital.
Subjects
Twenty-five patients in the early postoperative period of cardiac surgery.
Measurements and main results
After verification of the adequate position of the PAC, measurements of mixed venous blood gas oxygen saturation, oxygen partial pressure (PO2), carbon dioxide partial pressure (PCO2), 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 PO2: −0.2±1.3 mmHg, venous PCO2: 0.1±0.9 mmHg, venous pH: 0±0.03, venous bicarbonates: 0.03±0.5 mmol/l.
Conclusion
Using the Bland & Altman method, we showed a satisfactory agreement between slow and fast mixed venous blood gas sampling techniques when measuring PO2, oxygen saturation, PCO2, pH and bicarbonates though a PAC.