Does End-tidal PCO2 Reflect Adequately Arterial PCO2 during One-lung Ventilation for Thoracoscopy? / 대한마취과학회지

ABSTRACT

BACKGROUND: Maintenance of normal arterial carbon dioxide tension (PaCO2) is not generally a problem if the same tidal volume can be maintained when changing from two-lung(TLV) to one-lung ventilation(OLV). However, there have been a few studies on the use of capnography in monitoring the adequacy of ventilation during one-lung anesthesia. We have therefore studied how closely end-tidal PCO2 (PETCO2) values reflect changes in PaCO2 in patients undergoing thoracoscopic sympathectomy during TLV and after transition to OLV. METHODS: We have measured arterial oxygen tension(PaO2), PaCO2, PETCO2, and (PaCO2-PETCO2) in 24 adult, either sex, patients by infra-red spectrometry. They were measured after induction of anesthesia, in supine position(TLVsup), after a lateral decubitus position(TLVlat), at 15 minutes after left OLV(OLVLt), after right OLV(OLVRt), and at 10 minutes in the supine position re-positioned at the end of the operation(TLVrep). Data were analyzed with a one-way analysis of variance with repeated measures followed by multiple comparision. The correlation between PaCO2 and PETCO2 were tested using linear regression. RESULTS: PaCO2 did not significantly change, whereas PETCO2 significantly decreased at OLVLt, OLVRt compared with TLVsup value (OLVLt, 29.7 mmHg OLVRt, 30.5 mmHg and TLVsup, 33.6 mmHg; P0.65, P<0.0006) CONCLUSIONS: In the patients undergoing thoracoscopic sympathectomy with TLV or OLV in the lateral decubitus position, PETCO2 is a reliable estimate of the PaCO2. However, when the operative time is prolonged the arterial PCO2 may be more reliable than PETCO2.