ABSTRACT
In 46 patients undergoing cardiac surgery blood PO2 was continuously monitored with an in-line oxygen electrode during cardiopulmonary bypass and readings were compared with intermittent measurements of samples on a blood gas analyser. In 35 patients in whom arterial PO2 was monitored, there were rapid changes in PO2 and the mean difference between the in-line electrode and the blood gas analyser was 6.63 kPa (p less than 0.001). Venous PO2 was monitored in 11 patients and, in contrast to the arterial readings, the venous PO2 was relatively stable. The mean difference between the in-line electrode readings and the blood gas analyser was 0.21 kPa (p less than 0.05). The advantages of continuous monitoring of blood PO2 are described and the relative merits of mixed venous PO2 and mixed venous oxygen saturation measurements are discussed.
Subject(s)
Blood Gas Analysis/instrumentation , Cardiopulmonary Bypass , Intraoperative Care , Monitoring, Physiologic/instrumentation , Adult , Aged , Electrodes , Female , Humans , Infant , Male , Middle Aged , Oxygen/blood , Oxygenators , Partial PressureABSTRACT
A transcutaneous electrochemical sensor designed to estimate arterial oxygen (Pao2) and carbon dioxide (Paco2) tensions simultaneously and continuously was evaluated in newborn infants with respiratory illnesses. After calibration with two dry gas mixtures the sensor gave estimates of Pao2 and Paco2 that were comparable with those obtained by two separate electrodes that are already established in clinical use.
Subject(s)
Carbon Dioxide/blood , Electrochemistry/instrumentation , Oxygen/blood , Respiration Disorders/blood , Calibration , Female , Humans , Infant, Newborn , Male , Partial PressureABSTRACT
The technique of intermittent sampling of blood during extracorporeal circulation and in vitro analysis to establish that the blood-gas status of the patient is within acceptable limits has drawbacks which may be overcome by continuous monitoring. An evaluation of an oxygen monitoring system and a comparison with a blood gas analyser have been performed. Blood of known PO2 was circulated at 15 degrees, 25 degrees and 37 degrees C in an extracorporeal system and the monitor readings and results from samples analysed on a blood gas analyser were compared with calculated partial pressures. There was no significant difference between the calculated value and the monitor readings but the blood gas analyser results were significantly lower (p less than 0.01) than the calculated values of the tonometered blood. The reasons for this difference and the potential clinical advantages of continuous monitoring are discussed.
