Functional brain network and trail making test changes following major surgery and postoperative delirium: a prospective, multicentre, observational cohort study

BACKGROUND: Delirium is a frequent complication after surgery in older adults and is associated with an increased risk of long-term cognitive impairment and dementia. Disturbances in functional brain networks were previously reported during delirium. We hypothesised that alterations in functional brain networks persist after remission of postoperative delirium and that functional brain network alterations are associated with long-term cognitive impairment. METHODS: In this prospective, multicentre, observational cohort study, we included older patients who underwent clinical assessments (including the Trail Making Test B [TMT-B]) and resting-state functional MRI (rs-fMRI) before and 3 months after elective surgery. Delirium was assessed on the first seven postoperative days. RESULTS: Of the 554 enrolled patients, 246 remained after strict motion correction, of whom 38 (16%) developed postoperative delirium. The rs-fMRI functional connectivity strength increased 3 months after surgery in the total study population (β=0.006; 95% confidence interval [CI]: 0.001-0.011; P=0.013), but it decreased after postoperative delirium (β=-0.015; 95% CI: -0.028 to 0.002; P=0.023). No difference in TMT-B scores was found at follow-up between patients with and without postoperative delirium. Patients with decreased functional connectivity strength declined in TMT-B scores compared with those who did not (β=11.04; 95% CI: 0.85-21.2; P=0.034). CONCLUSIONS: Postoperative delirium was associated with decreased brain functional connectivity strength after 3 months, suggesting that delirium has a long-lasting impact on brain networks. The decreased connectivity strength was associated with significant cognitive deterioration after major surgery. CLINICAL TRIAL REGISTRATION: NCT02265263

Perioperative Quality Initiative (POQI) consensus statement on the physiology of blood pressure control as applied to perioperative medicine.

Background: A multi-disciplinary, international working subgroup of the Third Perioperative Quality Initiative (POQI) consensus meeting reviewed the (patho)physiology and measurement of arterial blood pressure (ABP), as applied to perioperative medicine. Methods: We addressed predefined questions by undertaking a modified Delphi analysis, in which primary clinical research and review articles were identified using MEDLINE. Strength of recommendations, where applicable, were graded by NICE guidelines. Results: Perioperative ABP management is a physiologically-complex challenge influenced by multiple factors: (i) ABP is the input pressure to organ blood flow, but is not the sole determinant of perfusion pressure; (ii) blood flow is often independent of changes in perfusion pressure, due to autoregulatory changes in vascular resistance; (iii) microvascular dysfunction uncouples microvascular blood flow from ABP (haemodynamic incoherence) From a practical clinical perspective, we identified that: (i) ambulatory measurement is the optimal method to establish baseline ABP; (ii) automated and invasive ABP measurements have inherent physiological and technical limitations; (iii) individualised ABP targets may change over time, especially during the perioperative period. There remains a need for research in non-invasive, continuous arterial pressure measurements, macro- and microcirculatory control, regional perfusion pressure measurement and the development of sensitive, specific and continuous measures of cellular function to evaluate blood pressure management in a physiologically coherent manner. Conclusion: The multivariable, complex physiology contributing to dynamic changes in perioperative ABP may be underappreciated clinically. The frequently unrecognised dissociation between ABP, organ blood flow, microvascular and cellular function requires further research that develops a more refined, contextualized clinical approach to this routine measurement

Risk Factors Associated with Ischemic Optic Neuropathy after Spinal Fusion Surgery

Background: Perioperative visual loss, a rare but dreaded complication of spinal fusion surgery, is most commonly caused by ischemic optic neuropathy (ION). The authors sought to determine risk factors for ION in this setting. Methods: Using a multicenter case-control design, the authors compared 80 adult patients with ION from the American Society of Anesthesiologists Postoperative Visual Loss Registry with 315 adult control subjects without ION after spinal fusion surgery, randomly selected from 17 institutions, and matched by year of surgery. Preexisting medical conditions and perioperative factors were compared between patients and control subjects using stepwise multivariate analysis to assess factors that might predicti ION. Results: After multivariate analysis, risk factors for ION after spinal fusion surgery included male sex (odds ratio [OR] 2.53, 95% CI 1.35-4.91, P = 0.005), obesity (OR 2.83, 95% CI 1.52-5.39, P = 0.001), Wilson frame use (OR 4.30, 95% CI 2.13-8.75, P < 0.001), anesthesia duration (OR per 1 h = 1.39, 95% CI 1.22-1.58, P < 0.001), estimated blood loss (OR per 1 l = 1.34, 95% CI 1.13-1.61, P = 0.001), and colloid as percent of nonblood replacement (OR per 5% = 0.67, 95% CI 0.52-0.82, P < 0.001). After cross-validation, area under the curve = 0.85, sensitivity = 0.79, and specificity = 0.82. Conclusions: This is the first study to assess ION risk factors in a large, multicenter case-control fashion with detailed perioperatiVe data. Obesity, male sex, Wilson frame use, longer anesthetic duration, greater estimated blood loss, and decreased percent colloid administration were significantly and independently associated with ION after spinal fusion surgery

Manual of preoperative and postoperative care, 2nd.ed/ The Committee on Pre and Postoperative Care

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