TY - THES ID - 136448661 TI - Arterial to end-tidal CO2 gradients during isocapnic hyperventilation AU - Jouwena, Jennifer AU - Van De Velde, Marc AU - Neyrinck, Arne AU - Hendrickx, Jan AU - KU Leuven. Faculteit Geneeskunde. Opleiding Master in de specialistische geneeskunde (uitdovend programma vanaf 2019-2020) (Leuven) PY - 2022 PB - Leuven KU Leuven. Faculteit Geneeskunde DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:136448661 AB - Purpose: Isocapnic hyperventilation (ICHV) is occasionally used to maintain the end-expired CO2 partial pressure (PEtCO2) when the inspired CO2 (PICO2) rises. Whether maintaining PEtCO2 with ICHV during an increase of the PICO2 also maintains arterial PCO2 (PaCO2) remains poorly documented. Methods: 12 ASA PS I - II patients 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. PICO2 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 PEtCO2 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 PICO2 level and compared using ANOVA. Results: Age, height, and weight were 66 (6) years, 171 (6) cm, and 75 (8) kg, respectively. Capnograms were normal and hemodynamic parameters remained stable. PEtCO2 could be maintained within 4.7 - 4.9% in all patients at all times except in 1 patient with 1.5% PICO2 and 5 patients with 2.0% PICO2; data from the one patient in whom both 1.5 and 2.0% PICO2 resulted in PEtCO2 > 5.1% were excluded from analysis. Pa-Et CO2 gradients did not change when PICO2 increased. Conclusion: The effect of a modest rise of PICO2 up to 1.5% on PEtCO2 during RARP can be readily overcome by increasing ventilation without altering the Pa-Et CO2 gradients. At higher PICO2, airway pressures may become a limiting factor, which requires further study. ER -