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Evaluation of a method for isocapnic hyperventilation: a clinical pilot trial
Author(s) -
Hallén K.,
Jildenstål P.,
Stenqvist O.,
Ricksten S.E.,
Lindgren S.
Publication year - 2018
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.13008
Subject(s) - medicine , hyperventilation , clinical trial , pilot trial , anesthesia , physical therapy , intensive care medicine , randomized controlled trial , surgery
Background Isocapnic hyperventilation ( IHV ) is a method that shortens time to extubation after inhalation anaesthesia using hyperventilation ( HV ) without lowering airway CO 2 . In a clinical trial on patients undergoing long‐duration sevoflurane anaesthesia for major ear–nose–throat ( ENT ) surgery, we evaluated the utility of a technique for CO 2 delivery ( DCO 2 ) to the inspiratory limb of a closed breathing circuit, during HV , to achieve isocapnia. Methods Fifteen adult ASA 1–3 patients were included. After end of surgery, mechanical HV was started by doubling baseline minute ventilation. Simultaneously, CO 2 was delivered and dosed using a nomogram developed in a previous experimental study. Time to extubation and eye opening was recorded. Inspired ( FICO 2 ) and expired ( FETCO 2 ) CO 2 and arterial CO 2 levels were monitored during IHV . Cognition was tested pre‐operatively and at 20, 40 and 60 min after surgery. Results A DCO 2 of 285 ± 45 ml/min provided stable isocapnia during HV (13.5 ± 4.1 l/min). The corresponding FICO 2 level was 3.0 ± 0.3%. Time from turning off the vaporizer (1.3 ± 0.1 MAC age) to extubation (0.2 ± 0.1 MAC age) was 11.3 ± 1.8 min after 342 ± 131 min of anaesthesia. Pa CO 2 and FETCO 2 remained at normal levels during and after IHV . In 85% of the patients, post‐operative cognition returned to pre‐operative values within 60 min. Conclusions In this cohort of patients, a DCO 2 nomogram for IHV was validated. The patients were safely extubated shortly after discontinuing long‐term sevoflurane anaesthesia. Perioperatively, there were no adverse effects on arterial blood gases or post‐operative cognition. This technique for IHV can potentially be used to decrease emergence time from inhalation anaesthesia.