Cerebral autoregulation and cerebral blood flow response to mean arterial pressure challenge following induction of general anaesthesia for neuroradiology procedure

IntroductionIntraoperative hypotension is common following general anaesthesia induction with propofol, but its impact on cerebral autoregulation (CA) remains unclear. We investigate the incidence and risk factors of impaired CApost-propofol induction and its recovery after a mean arterial pressure (mAP) challenge.MethodsWe included 40 non-emergency neuroradiology surgery patients [58 (47, 58)years old., 57% women]. We recorded mAP, mean blood flow velocity in the mean cerebral artery (MCAvmean), and regional cerebral oxygen saturation (rSO2). We computed the mean flow index (Mxa) pre and post mAP challenge. Mxa > 0.3 defined poor CA.ResultsAfter anaesthesia induction, 21 (53%) had impaired CBF autoregulation (CA−, Mxa > 0.3). The average mAP was 66 ± 9 mmHg, average MCAv was 39 ± 12 cm.s−1, and rSO2 was 63 ± 7%. We found no significant difference in age, norepinephrine infusion rate, and cardiovascular risks factors were similar between CA− and CA+ (Mxa ≤ 0.3) patients. Among the 22 patients (CA−: n = 14; CA+: n = 8) undergoing mAP challenge, there was a significant Mxa improvement and MCAv increase among CA− patients, (CA−: 0.63 ± 0.18 vs. 0.28 ± 0.20, p < 0.001), and [absolute variation: 1 (0.7–1.5) vs. 7 (3–9) cm.sec−1], respectively.ConclusionAfter induction of general anaesthesia for neuroradiology procedure, 53% of the patients had an impaired CA, regardless of age or medical history. Importantly, a mAP challenge effectively restored CA and improved CBF.Clinical Trial Registrationidentifier, NCT0428886

Neurovascular coupling methods in healthy individuals using transcranial Doppler ultrasonography: A systematic review and consensus agreement

Neurovascular coupling (NVC) is the perturbation of cerebral blood flow (CBF) to meet varying metabolic demands induced by various levels of neural activity. NVC may be assessed by Transcranial Doppler ultrasonography (TCD), using task activation protocols, but with significant methodological heterogeneity between studies, hindering cross-study comparisons. Therefore, this review aimed to summarise and compare available methods for TCD-based healthy NVC assessments. Medline (Ovid), Scopus, Web of Science, EMBASE (Ovid) and CINAHL were searched using a predefined search strategy (PROSPERO: CRD42019153228), generating 6006 articles. Included studies contained TCD-based assessments of NVC in healthy adults. Study quality was assessed using a checklist, and findings were synthesised narratively. 76 studies (2697 participants) met the review criteria. There was significant heterogeneity in the participant position used (e.g., seated vs supine), in TCD equipment, and vessel insonated (e.g. middle, posterior, and anterior cerebral arteries). Larger, more significant, TCD-based NVC responses typically included a seated position, baseline durations >one-minute, extraneous light control, and implementation of previously validated protocols. In addition, complementary, combined position, vessel insonated and stimulation type protocols were associated with more significant NVC results. Recommendations are detailed here, but further investigation is required in patient populations, for further optimisation of TCD-based NVC assessments

Cerebral autoregulation and cerebral blood flow response to mean arterial pressure challenge following induction of general anaesthesia for neuroradiology procedure

International audienceIntroduction Intraoperative hypotension is common following general anaesthesia induction with propofol, but its impact on cerebral autoregulation (CA) remains unclear. We investigate the incidence and risk factors of impaired CApost-propofol induction and its recovery after a mean arterial pressure (mAP) challenge. Methods We included 40 non-emergency neuroradiology surgery patients [58 (47, 58)years old., 57% women]. We recorded mAP, mean blood flow velocity in the mean cerebral artery (MCAv$_{ mean}$ ), and regional cerebral oxygen saturation (rSO2). We computed the mean flow index (Mxa) pre and post mAP challenge. Mxa > 0.3 defined poor CA. Results After anaesthesia induction, 21 (53%) had impaired CBF autoregulation (CA−, Mxa < 0.3). The average mAP was 66 ± 9 mmHg, average MCAv was 39 ± 12 cm.s$^{−1}$ , and rSO 2 was 63 ± 7%. We found no significant difference in age, norepinephrine infusion rate, and cardiovascular risks factors were similar between CA− and CA+ (Mxa ≤ 0.3) patients. Among the 22 patients (CA−: n = 14; CA+: n = 8) undergoing mAP challenge, there was a significant Mxa improvement and MCAv increase among CA− patients, (CA−: 0.63 ± 0.18 vs. 0.28 ± 0.20, p < 0.001), and [absolute variation: 1 (0.7–1.5) vs. 7 (3–9) cm.sec$^{−1}$ ], respectively. Conclusion After induction of general anaesthesia for neuroradiology procedure, 53% of the patients had an impaired CA, regardless of age or medical history. Importantly, a mAP challenge effectively restored CA and improved CBF. Clinical Trial Registration identifier, NCT0428886

Propofol Requirement and EEG Alpha Band Power During General Anesthesia Provide Complementary Views on Preoperative Cognitive Decline

International audienceBackground: Although cognitive decline (CD) is associated with increased post-operative morbidity and mortality, routinely screening patients remains difficult. The main objective of this prospective study is to use the EEG response to a Propofol-based general anesthesia (GA) to reveal CD. Methods: 42 patients with collected EEG and Propofol target concentration infusion (TCI) during GA had a preoperative cognitive assessment using MoCA. We evaluated the performance of three variables to detect CD (MoCA &lt; 25 points): age, Propofol requirement to induce unconsciousness (TCI at SEF 95 : 8–13 Hz) and the frontal alpha band power (AP at SEF 95 : 8–13 Hz). Results: The 17 patients (40%) with CD were significantly older ( p &lt; 0.001), had lower TCI ( p &lt; 0.001), and AP ( p &lt; 0.001). We found using logistic models that TCI and AP were the best set of variables associated with CD (AUC: 0.89) and performed better than age ( p &lt; 0.05). Propofol TCI had a greater impact on CD probability compared to AP, although both were complementary in detecting CD. Conclusion: TCI and AP contribute additively to reveal patient with preoperative cognitive decline. Further research on post-operative cognitive trajectory are necessary to confirm the interest of intra operative variables in addition or as a substitute to cognitive evaluation

Impact of impaired cerebral blood flow autoregulation on electroencephalogram signals in adults undergoing propofol anaesthesia: a pilot study

International audienceBackground: Cerebral autoregulation actively maintains cerebral blood flow over a range of MAPs. During general anaesthesia, this mechanism may not compensate for reductions in MAP leading to brain hypoperfusion. Cerebral autoregulation can be assessed using the mean flow index derived from Doppler measurements of average blood velocity in the middle cerebral artery, but this is impractical for routine monitoring within the operating room. Here, we investigate the possibility of using the EEG as a proxy measure for a loss of cerebral autoregulation, determined by the mean flow index. Methods: Thirty-six patients (57.5 [44.25; 66.5] yr; 38.9% women, non-emergency neuroradiology surgery) anaesthetised using propofol were prospectively studied. Continuous recordings of MAP, average blood velocity in the middle cerebral artery, EEG, and regional cerebral oxygen saturation were made. Poor cerebral autoregulation was defined as a mean flow index greater than 0.3. Results: Eighteen patients had preserved cerebral autoregulation, and 18 had altered cerebral autoregulation. The two groups had similar ages, MAPs, and average blood velocities in the middle cerebral artery. Patients with altered cerebral autoregulation exhibited a significantly slower alpha peak frequency (9