CONTINUOUS INTRAVASCULAR BLOOD GLAS ANALY SIS - CLINICAL-EVALUATION OF A NEW FIBER OPTIC MONITOR

Continuous monitoring of blood gases and pH could add substantially to patient safety. During the last decade, efforts have been made to dev elop continuous optochemical blood gas sensors. The initial evaluation of such fibreoptic-based systems showed major patient-interface probl ems [11]. We evaluated a new intra-arterial blood gas monitoring syste m (PB3300, Puritan-Bennett, Carlsbad CA) under routine clinical condit ions. Methods. After institutional review board approval and with writ ten informed consent, 38 sensors were tested in 25 patients with acute respiratory failure (e.g., the acute respiratory distress syndrome, c omplications after lung transplantation). Two conventional bench-top b lood gas analysers (ABL 520 and ABL 300, Radiometer, Copenhagen) serve d as criterion standards. The mean differences (bias) and standard dev iations (SD) of the differences (precision) were calculated according to the method of Bland and Altman [2]. In addition, linear regression analysis and correlation coefficients were calculated. The quality of blood pressure tracings was assessed using a grading system. Results. The median sensor lifetime was 81.3 h; 869 blood samples (median 14 pe r sensor) were analysed for the comparison of continuous and conventio nal blood gas analysis. The ranges for measured parameters were: pH: 6 .92 to 7.55; PCO2: 20 to 83 torr; PO2: 31 to 518 torr. The mean differ ences (SD) were: pH: -0.03 (0.03) or -0.4 (0.4)%; PCO2: -2.6 (4.1) tor r or -6.9 (10.9)%; PO2: -3.4 (10.5) torr or -2.9 (7.0)%. The results o f linear regression analysis and the correlation coefficients are depi cted in Table 2. The mean grade of blood pressure tracings was satisfa ctory for the clinical setting. Conclusions. The continuous blood gas monitor is sufficiently accurate and precise for clinical use. Bias an d precision are better than those known from former studies evaluating fibreoptic blood gas monitors under experimental conditions [7]. Cost -effectiveness was not an issue of this study.