BACKGROUND Monitoring oxygen consumption (VO2) is neither recommended nor included in peri-operative haemodynamic algorithms aiming at optimising oxygen delivery (DO2) in major abdominal surgery. Estimates of peri-operative VO2 changes are uncertain in earlier publications and have limited generalisability in the current high-risk surgical population. In a prospective non-interventional observational study in elderly patients undergoing major abdominal procedures, we investigated the change of VO2 after induction of anaesthesia and secondarily, the further changes during and after surgery in relation to DO2 and estimated oxygen extraction ratio (O2ER) by routine monitoring. METHODS VO2 was determined by indirect calorimetry (QuarkRMR) in 20 patients more than 65 years (ASA II to IV), scheduled for elective open upper abdominal surgery with combined epidural and general anaesthesia. Data were collected during 20-minute periods pre-operatively and after anaesthesia induction, with subsequent measurements during surgery and postoperatively. Simultaneously, DO2 was monitored using LiDCOplus. The O2ER was estimated from arterial–central venous oxygen content calculation. Mixed models were used to analyse the peri-operative changes. RESULTS VO2 decreased after induction of anaesthesia by a mean of 34% (95% CI, 28 to 39). After 2 h of surgery, VO2 was reduced by 24% (95% CI, 20 to 27) compared with the awake baseline measurements. Pre-operative mean DO2 was 440 (95% CI, 396 to 483) ml min−1 m−2 and decreased by a mean of 37% (95% CI, 30 to 43) during anaesthesia. The estimated O2ER did not change intra-operatively 0.24 (95% CI, 0.21 to 0.26) but increased postoperatively to 0.31 (95% CI, 0.27 to 0.36). The changes of VO2 were parallel with changes of DO2 and O2ER in the intra-operative period. CONCLUSION General anaesthesia reduced VO2 by approximately a third in elderly patients undergoing major abdominal surgery. Parallel changes of intra-operative VO2 and delivery were demonstrated while oxygen extraction was low. The relevance of these changes needs further assessment in relation to outcomes and haemodynamic interventions. TRIAL REGISTRATION Clinicaltrials.gov NCT 03355118.
Feasible estimations of perioperative changes in oxygen consumption could enable larger studies of its role in postoperative outcomes. Current methods, by pulmonary artery catheterisation or breathing gas analysis, are often regarded as either invasive or technically requiring. In this pilot study, we investigated the relationship between estimations of oxygen consumption, based on minimal-invasive cardiac output and arterial-central venous blood gas sampling, and indirect calorimetry in the perioperative period using the data collected during a clinical trial on perioperative oxygen transport.In 20 patients >65 years during epidural and general anaesthesia for open abdominal surgery, Fick-based estimations of oxygen consumption(EVO2), the product of cardiac output from LiDCO™plus(LiDCO Ltd, Cambridge, UK) and arterial-central venous oxygen content difference, were compared with indirect calorimetry(GVO2) using QuarkRMR(COSMED, srl. Italy). Eighty-five simultaneous intra- and postoperative measurements at different time-points were analysed for prediction, parallelity and by traditional agreement assessment. There was an overall association between GVO2 and EVO2, 73(95% CI 62 to 83) + 0.45(95% CI 0.29 to 0.61) EVO2 ml min-1m-2, P<0.0001. GVO2 and EVO2 changed in parallel intra- and postoperatively when normalised to their respective overall means. Unadjusted mean difference between GVO2 and EVO2 indexed for body surface area was 26(95% CI 20 to 32) with limits of agreement (1.96SD) of -32 to 85 ml min-1m-2 and did not change over time. There was low correlation for absolute agreement, ICC(A,1) 0.37(95% CI 0.34 to 0.65) [F(84,10.2)=3.07, P=0.0266].Despite lack of absolute agreement, the estimated oxygen consumption changed in parallel to the metabolic measurements in the perioperative period. Prediction or trending of oxygen consumption by this or similar methods could be further evaluated in larger samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.