Résumé
End-tidal carbon dioxide tension or concentration monitoring is characterized with noninvasive,convenient and fast reaction,which Can be continuously monitored and dynamically displayed On electrocardiogram monitor.The technique has been extensively applied in the operation room,intensive care unit and emergency room.
Résumé
BACKGROUND: The monitoring of end-tidal carbon dioxide tension (PETCO2) and oxygen supply may be required in spontaneously breathing patients during spinal anesthesia, particulary in cases involving high spinal block, underlying pulmonary disease, and use of a sedative drug. We investigated changes in PETCO2 and arterial oxygen tension versus oxygen flow rate via a nasal cannula, and the correlation between arterial carbon dioxide tension (PaCO2) and PETCO2 in spontaneously breathing patients during spinal anesthesia. METHODS: Thirty adult patients participated in this study. We performed spinal anesthesia with an optimal dose of heavy marcaine. After determining the sensory blockade level, PETCO2 was sampled from hub of a 14-gauge central catheter piercing one of the two nasal oxygen prongs, and oxygen flow rates (2, 3, 4 or 5 L/min) were measured by on-line capnography. The oxygen flow rates were varied every 5 minutes, and PETCO2 values and arterial samples for PaCO2 and arterial oxygen tension (PaO2) analysis were obtained at the end of each 5-minute period. RESULTS: No significant difference in PETCO2 was observed at the different oxygen flow rates. The results show that PETCO2 correlates closely with PaCO2 irrespective of oxygen flow rate. The PaO2 values were; 155.7 +/- 26.3, 192.7 +/- 36.6, 217.0 +/- 40.6 and 241.4 +/- 51.3 mmHg at nasal oxygen flow rates of 2, 3, 4 and 5 L/min, respectively. CONCLUSIONS: The measurement of PETCO2 via this nasal cannula was useful for continuous, noninvasive monitoring during spinal anesthesia irrespective of oxygen flow rate.
Sujets)
Adulte , Humains , Rachianesthésie , Bupivacaïne , Capnographie , Dioxyde de carbone , Cathéters , Maladies pulmonaires , Oxygène , RespirationRésumé
BACKGROUND: Maintenance of adequate concentration of carbon dioxide during hypothermic cardiopulmonary bypass is important in order to improve tissue perfusion by maintaining vasodilatation. This study evaluated the usefulness of the analysis of gas sampled from the exhaust port of a membrane oxygenator in the estimation of carbon dioxide tension in arterial blood (PaCO2). METHODS: One hundred sixty four arterial blood gases were drawn from 45 adult and 30 pediatric cardiac surgical patients undergoing hypothermic cardiopulmonary bypass. Carbon dioxide tensions were measured in the membrane oxygenator exhaust gas (swept gas; PswCO2) using a capnography and in arterial blood using intermittent gas analysis. We compared the PswCO2 with temperature-uncorrected (alpha-stat) and -corrected (pH-stat) PaCO2 during cardiopulmoary bypass. RESULTS: The mean PaCO2 measured with alpha-stat and pH-stat, and PswCO2 obtained in adult patients during hypothermic cardiopulmonary bypass were 29.8 +/- 4.9, 19.5 +/- 4.1 and 22.3 +/- 4.2 mmHg, respectively. In pediatric patients, alpha-stat PaCO2, pH-stat PaCO2 and PswCO2 were 39.7 +/- 7.7, 24.7 +/- 6.2 and 20.3 +/- 6.0 mmHg, respectively. There was a significant positive correlation between PswCO2 and alpha-stat PaCO2 (adult patients: slope = 0.49, r = 0.64, P < 0.001; pediatric patients: slope = 0.53, r = 0.68, P < 0.001) and pH-stat PaCO2 (adult patients: slope = 0.85, r = 0.81, P < 0.001; pediatric patients: slope = 0.73, r = 0.73, P < 0.001). On comparison of subsequent measurements, 3.8% (adult patients) and 11.4% (pediatric patients) of changes in PaCO2 and PswCO2 were in opposite direction. CONCLUSIONS: Our results indicate that in adult and pediatric patients undergoing hypothermic cardiopulmonary bypass PswCO2 can be an indicator of changes in trend of PaCO2.