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Modelling of the Effect of End‐Tidal Carbon Dioxide on Cerebral Oxygen Saturation in Beach Chair Position under General Anaesthesia
Author(s) -
Kim So Yeon,
Chae Dong Woo,
Chun YongMin,
Jeong Kyu Hee,
Park Kyungsoo,
Han Dong Woo
Publication year - 2016
Publication title -
basic and clinical pharmacology and toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.805
H-Index - 90
eISSN - 1742-7843
pISSN - 1742-7835
DOI - 10.1111/bcpt.12549
Subject(s) - hypercapnia , medicine , anesthesia , desflurane , general anaesthesia , remifentanil , diabetes mellitus , anesthetic , propofol , endocrinology , acidosis
Patients undergoing shoulder surgery in the beach chair position ( BCP ) under general anaesthesia may be at risk of cerebral desaturation. Increasing end‐tidal carbon dioxide (Et CO 2 ) is the most convenient and powerful method for the management of cerebral desaturation. The purpose of this study was to investigate the quantitative relationship between Et CO 2 and cerebral oxygen saturation ( rSO 2 ) and to identify the associated influencing factors. Fifty‐one patients undergoing arthroscopic shoulder surgery in the BCP under general anaesthesia completed this study. Desflurane and remifentanil were used, and Et CO 2 was steadily increased and then decreased by adjusting the ventilator settings every 3 min. so that time lag of rSO 2 response to Et CO 2 changes could be delineated. Near‐infrared spectroscopy was used to monitor rSO 2 response. An indirect response model was used to examine the relationship between Et CO 2 and rSO 2 . To determine the relevant covariates, a stepwise approach was used. There was a linear relationship between rSO 2 and Et CO 2 with a slight delay in the peak of rSO 2 relative to Et CO 2 . Increase in end‐tidal desflurane concentration led to a slower response of rSO 2 to the changes of Et CO 2 ( p = 0.0002). The presence of diabetes mellitus reduced the reactivity of rSO 2 to Et CO 2 changes ( p < 0.0001). This model‐based approach revealed that diabetes mellitus attenuates the response of rSO 2 to changes in Et CO 2 . The management of cerebral desaturation by hypercapnia in patients with diabetes may be less effective than in non‐diabetic patients under general anaesthesia with BCP.