Mismatch of arterial and central venous blood gas analysis during haemorrhage.
OBJECTIVE
Arterial base excess and lactate levels are key parameters in the assessment of critically ill patients. The use of venous blood gas analysis may be of clinical interest when no arterial blood is available initially.


METHODS
Twenty-four pigs underwent progressive normovolaemic haemodilution and subsequent progressive haemorrhage until the death of the animal. Base excess and lactate levels were determined from arterial and central venous blood after each step. In addition, base excess was calculated by the Van Slyke equation modified by Zander (BE(z)). Continuous variables were summarized as mean +/- SD and represent all measurements (n = 195).


RESULTS
Base excess according to National Committee for Clinical Laboratory Standards for arterial blood was 2.27 +/- 4.12 versus 2.48 +/- 4.33 mmol(-l) for central venous blood (P = 0.099) with a strong correlation (r(2) = 0.960, P < 0.001). Standard deviation of the differences between these parameters (SD-DIFBE) did not increase (P = 0.355) during haemorrhage as compared with haemodilution. Arterial lactate was 2.66 +/- 3.23 versus 2.71 +/- 2.80 mmol(-l) in central venous blood (P = 0.330) with a strong correlation (r(2) = 0.983, P < 0.001). SD-DIFLAC increased (P < 0.001) during haemorrhage. BE(z) for central venous blood was 2.22 +/- 4.62 mmol(-l) (P = 0.006 versus arterial base excess according to National Committee for Clinical Laboratory Standards) with strong correlation (r(2) = 0.942, P < 0.001). SD-DIFBE(z)/base excess increased (P < 0.024) during haemorrhage.


CONCLUSIONS
Central venous blood gas analysis is a good predictor for base excess and lactate in arterial blood in steady-state conditions. However, the variation between arterial and central venous lactate increases during haemorrhage. The modification of the Van Slyke equation by Zander did not improve the agreement between central venous and arterial base excess.
Theusinger
Oliver M
OM
Institute of Anaesthesiology, University Hospital Zurich, Zurich. oliver.theusinger@usz.ch
Thyes
Caroline
C
Frascarolo
Philippe
P
Schramm
Sebastian
S
Seifert
Burkhardt
B
Spahn
Donat R
DR
D000137:Acid-Base Imbalance / Q000097:blood*; D000818:Animals; D001784:Blood Gas Analysis / Q000379:methods*; D016638:Critical Illness; D006438:Hemodilution / Q000379:methods; D006470:Hemorrhage / Q000503:physiopathology*; D007773:Lactates / Q000097:blood; D013552:Swine
D007773:Lactates