Continuous monitoring of arterial blood gases and pH during intraoperativerapid blood administration using a paratrend sensor

Background and Objectives: The aim of this study was to determine the effec ts of rapid transfusion of packed red cells on the arterial blood gases and acid-base status of the recipient. Materials and Methods: We studied 16 pa tients (mean age 66.3 +/- 9.9 years) who received rapid transfusion of 632. 8 +/- 287.2 g of packed red cells in CPDA-1, stored before use for a period of 15.2 +/- 4.4 days. During transfusion, monitoring of pH, PCO2 and PO2 w as continuous using an intra-arterial multiparameter sensor (Paratrend 7, B iomedical Sensors, UK), Results: The rate of the transfusion was 73.1 +/- 9 .6 g/min and the duration of observation was 35.8 +/- 12.8 min. Arterial pH decreased from 7.446 +/- 0.023 to 7.385 +/- 0.034 (p < 0.001) and PCO2 inc reased from 32.31 +/- 1.35 to 36.41 +/- 1.86 mmHg (p<0.001). Delta pH and D elta PCO2 showed significant correlation to the weight and the age of the t ransfused blood (p<0.001 for both dependent variables). The rate of pH chan ge was positively but insignificantly correlated to the rate of the transfu sion. Base excess was significantly decreased and end-tidal CO2 (PetCO(2)) was increased from 25.8 +/- 2.0 to 28.1 +/- 2.3 mmHg (p < 0.05), significan tly correlating to the amount and age of the administered component (p < 0. 05), PetCO(2) was not elevated when PCO2 changes were minimal. Alterations in PO2 were not specific and our clinical impression was that they were rel ated to unmeasured parameters. Conclusion: Our findings suggest that the fa ll in pH and the elevation in PCO2 which occur during rapid transfusion of packed red cells may go undetected or be misinterpreted if the acid-base st atus of the recipient is not monitored continously. These alterations are m ainly of metabolic character and depend on the amount and age of the transf used component. Our data suggest that arterial sampling is essential during massive transfusions. Copyright (C) 2000 S. Karger AG, Basel.