CONTINUOUS FIBEROPTIC ARTERIAL AND VENOUS-BLOOD GAS MONITORING IN HEMORRHAGIC-SHOCK

Study objective: To compare the performance of continuous fiberoptic b lood gas monitoring with standard, intermittent blood gas sampling in the measurement of arterial and central venous blood gases during mark ed hemodynamic changes. Design: Prospective, consecutive, enrollment, experimental study, Setting: Research laboratory at a university medic al center, Participants: Seven anesthetized, mechanically ventilated p igs, Interventions: Severe shock was induced by hemorrhage in pigs mon itored by a pulmonary artery catheter, an arterial line, and two fiber optic blood gas sensors: one intra-arterial, and the other inserted in to the superior vena cava via right internal jugular vein cutdown. Fib eroptic blood gas monitor measurements were compared with standard int ermittent blood gas sampling, Measurements and results: A total of 184 blood gas samples were compared in seven animals at baseline, during shock, and after resuscitation. The baseline mean (+/-1 SD) cardiac ou tput decreased from 4.0+/-0.9 to 1.2+/-0.6 L/min during shock and retu rned to baseline after retransfusion (3.9+/-1.3 L/min), The comparison of continuous fiberoptic blood gas monitoring with intermittent blood gas sampling showed a bias+/-precision of 0.035+/-0.047 for arterial pH, 0.021+/-0.031 for central venous pH, -4.09+/-2.96 mm Hg(-0.55+/-0. 39 kPa) for arterial PCO2, -3.67+/-2.44 mm Hg (-0.49+/-0.33 kPa) for c entral venous PCO2, -5.79+/-9.64 mm Hg (-0.77+/-1.29 kPa) for arterial PO2, and -7.85+/-8.52 mm Hg (-1.05+/-1.14 kPa) for central venous PO2 . Conclusions: Continuous fiberoptic blood gas monitoring agrees close ly with standard intermittent blood gas sampling during severe hemodyn amic shifts and has a comparable accuracy for both arterial and venous blood gas measurements, Changes in venous PCO2 have recently been sho wn to correlate with changes in global tissue per-fusion (eg, changes in cardiac output). Such data, available immediately via continuous ve nous blood gas monitoring, may be useful for monitoring shock and the response to resuscitation.