Near-infrared spectroscopy assessed cerebral oxygenation during open abdominal aortic aneurysm repair: relation to end-tidal CO2 tension

Abstract

During open abdominal aortic aneurism (AAA) repair cerebral blood flow is challenged. Clamping of the aorta may lead to unintended hyperventilation as metabolism is reduced by perfusion of a smaller part of the body and reperfusion of the aorta releases vasodilatory substances including CO2. We intend to adjust ventilation according end-tidal CO2 tension (EtCO2) and here evaluated to what extent that strategy maintains frontal lobe oxygenation (ScO2) as determined by near infrared spectroscopy. For 44 patients [5 women, aged 70 (48-83) years] ScO2, mean arterial pressure (MAP), EtCO2, and ventilation were obtained retrospectively from the anesthetic charts. By clamping the aorta, ScO2 and EtCO2 were kept stable by reducing ventilation (median, -0.8 l min(-1); interquartile range, -1.1 to -0.4; P < 0.001). During reperfusion of the aorta a reduction in MAP by 8 mmHg (-15 to -1; P < 0.001) did not prevent an increase in ScO2 by 2 % (-1 to 4; P < 0.001) as EtCO2 increased 0.5 kPa (0.1-1.0; P < 0.001) despite an increase in ventilation by 1.8 l min(-1) (0.9-2.7; P < 0.001). Changes in ScO2 related to those in EtCO2 (r = 0.41; P = 0.0001) and cerebral deoxygenation (-15 %) was noted in three patients while cerebral hyperoxygenation (+15 %) manifests in one patient. Thus changes in ScO2 were kept within acceptable limits (±15 %) in 91 % of the patients. For the majority of the patients undergoing AAA repair ScO2 was kept within reasonable limits by reducing ventilation by approximately 1 l min(-1) upon clamping of the aorta and increasing ventilation by approximately 2 l min(-1) when the lower body is reperfused.

Low vs high hemoglobin trigger for transfusion in vascular surgery: a randomized clinical feasibility trial

“…The required sample size for the desaturation load could not be estimated because of a lack of background data. 27 All analyses were based on the intention-to-treat population and adjusted for age and type of surgery. 28 Postoperative Hb (longitudinal outcome) was analyzed with generalized estimated equations (GEE), using STATA (version 15/MP).…”

Cerebral Tissue Oxygen Saturation Is Enhanced in Patients following Transcatheter Aortic Valve Implantation: A Retrospective Study

“…This means that, within physiological ranges, cerebral blood flow enhances linearly with rising PaCO 2 [ 34 , 35 ]. The relation of PaCO 2 and rSO 2 has been examined in various clinical settings using wide ranges of target PaCO 2 , from 35 mmHg to 55 mmHg [ 36 , 37 , 38 , 39 ]. rSO 2 increases in association with PaCO 2 , but the magnitude of this increase is not fully understood.…”

Elevated Renal Oxygen Extraction During Open Abdominal Aortic Aneurysm Repair Is Related to Postoperative Renal Dysfunction

“…Maintenance of anesthesia was with propofol (0.08 mg/[kg*min]) and remifentanil (0.3-0.4 µg/ [kg*min]). Following oral intubation, 70% O 2 was provided and ventilation aimed at an end-tidal CO 2 tension of 4.5 to 5.0 kPa 18 (Dräger CATO M32040, Drägerwerk, Lübeck, Germany). For epidural anesthesia bupivacaine (15-25 mg) was followed by infusion at 20 mg/h.…”