학술논문
Arterial to end-tidal CO2 gradients during isocapnic hyperventilation
Document Type
Original Paper
Author
Source
Journal of Clinical Monitoring and Computing. 37(1):311-317
Subject
Language
English
ISSN
1387-1307
1573-2614
1573-2614
Abstract
Isocapnic hyperventilation (ICHV) is occasionally used to maintain the end-expired CO2 partial pressure (PET CO2 ) when the inspired CO2 (PI CO2 ) rises. Whether maintaining PET CO2 with ICHV during an increase of the PI CO2 also maintains arterial PCO2 (Pa CO2 ) remains poorly documented. 12 ASA PS I–II subjects undergoing a robot-assisted radical prostatectomy (RARP) (n = 11) or cystectomy (n = 1) under general endotracheal anesthesia with sevoflurane in O2 /air (40% inspired O2 ) were enrolled. PI CO2 was sequentially increased from 0 to 0.5, 1.0, 1.5 and 2% by adding CO2 to the inspiratory limb of the circle system, while increasing ventilation to a target PET CO2 of 4.7–4.9% by adjusting respiratory rate during controlled mechanical ventilation. Pa-ET CO2 gradients were determined after a 15 min equilibration period at each PI CO2 level and compared using ANOVA. Mean (standard deviation) age, height, and weight were 66 (6) years, 171 (6) cm, and 75 (8) kg, respectively. Capnograms were normal and hemodynamic parameters remained stable. PET CO2 could be maintained within 4.7–4.9% in all subjects at all times except in 1 subject with 1.5% PI CO2 and 5 subjects with 2.0% PI CO2 ; data from the one subject in whom both 1.5 and 2.0% PI CO2 resulted in PET CO2 > 5.1% were excluded from analysis. Pa-ET CO2 gradients did not change when PI CO2 increased. The effect of a modest rise of PI CO2 up to 1.5% on PET CO2 during RARP can be readily overcome by increasing ventilation without altering the Pa-ET CO2 gradients. At higher PI CO2 , airway pressures may become a limiting factor, which requires further study.