Dose-dependent relationship between intra-procedural hypoxaemia or hypocapnia and postoperative delirium in older patients.

BACKGROUND: Previous studies indicated an association between impaired cerebral perfusion and post-procedural neurological disorders. We investigated whether intra-procedural hypoxaemia or hypocapnia are associated with delirium after surgery. METHODS: Inpatients ≥60 yr of age undergoing anaesthesia for surgical or interventional procedures between 2009 and 2020 at an academic healthcare network in the USA (Massachusetts) were included in this hospital registry study. The primary exposure was intra-procedural hypoxaemia, defined as peripheral oxygen saturation <90% for >2 cohering min. The co-primary exposure was hypocapnia during general anaesthesia, defined as end-tidal carbon dioxide pressure ≤25 mm Hg for >5 cohering min. The primary outcome was delirium within 7 days after surgery. RESULTS: Of 71 717 included patients, 1702 (2.4%) developed postoperative delirium, and hypoxaemia was detected in 2532 (3.5%). Of 42 894 patients undergoing general anaesthesia, 532 (1.2%) experienced hypocapnia. The occurrence of either hypoxaemia (adjusted odds ratio [ORadj]=1.71; 95% confidence interval [CI], 1.40-2.07; P<0.001) or hypocapnia (ORadj=1.77; 95% CI, 1.30-2.41; P<0.001) was associated with a higher risk of delirium within 7 days. Both associations were dependent on the magnitude, and increased with event duration (ORadj=1.03; 95% CI, 1.02-1.04; P<0.001 and ORadj=1.01; 95% CI, 1.00-1.01; P=0.005, for each minute increase in the longest continuous episode, respectively). There was no association between occurrence of hypercapnia and postoperative delirium (ORadj=1.24; 95% CI, 0.90-1.71; P=0.181). CONCLUSIONS: Intra-procedural hypoxaemia and hypocapnia were dose-dependently associated with a higher risk of postoperative delirium. These findings support maintaining normal gas exchange to avoid postoperative neurological disorders.

Association Between Intraoperative Arterial Hypotension and Postoperative Delirium After Noncardiac Surgery: A Retrospective Multicenter Cohort Study.

BACKGROUND: It is unclear whether intraoperative arterial hypotension is associated with postoperative delirium. We hypothesized that intraoperative hypotension within a range frequently observed in clinical practice is associated with increased odds of delirium after surgery. METHODS: Adult noncardiac surgical patients undergoing general anesthesia at 2 academic medical centers between 2005 and 2017 were included in this retrospective cohort study. The primary exposure was intraoperative hypotension, defined as the cumulative duration of an intraoperative mean arterial pressure (MAP) <55 mm Hg, categorized into and short (<15 minutes; median [interquartile range {IQR}], 2 [1-4] minutes) and prolonged (≥15 minutes; median [IQR], 21 [17-31] minutes) durations of intraoperative hypotension. The primary outcome was a new diagnosis of delirium within 30 days after surgery. In secondary analyses, we assessed the association between a MAP decrease of >30% from baseline and postoperative delirium. Multivariable logistic regression adjusted for patient- and procedure-related factors, including demographics, comorbidities, and markers of procedural severity, was used. RESULTS: Among 316,717 included surgical patients, 2183 (0.7%) were diagnosed with delirium within 30 days after surgery; 41.7% and 2.6% of patients had a MAP <55 mm Hg for a short and a prolonged duration, respectively. A MAP <55 mm Hg was associated with postoperative delirium compared to no hypotension (short duration of MAP <55 mm Hg: adjusted odds ratio [ORadj], 1.22; 95% confidence interval [CI], 1.11-1.33; P < .001 and prolonged duration of MAP <55 mm Hg: ORadj, 1.57; 95% CI, 1.27-1.94; P < .001). Compared to a short duration of a MAP <55 mm Hg, a prolonged duration of a MAP <55 mm Hg was associated with greater odds of postoperative delirium (ORadj, 1.29; 95% CI, 1.05-1.58; P = .016). The association between intraoperative hypotension and postoperative delirium was duration-dependent (ORadj for every 10 cumulative minutes of MAP <55 mm Hg: 1.06; 95% CI, 1.02-1.09; P =.001) and magnified in patients who underwent surgeries of longer duration (P for interaction = .046; MAP <55 mm Hg versus no MAP <55 mm Hg in patients undergoing surgery of >3 hours: ORadj, 1.40; 95% CI, 1.23-1.61; P < .001). A MAP decrease of >30% from baseline was not associated with postoperative delirium compared to no hypotension, also when additionally adjusted for the cumulative duration of a MAP <55 mm Hg (short duration of MAP decrease >30%: ORadj, 1.13; 95% CI, 0.91-1.40; P = .262 and prolonged duration of MAP decrease >30%: ORadj, 1.19; 95% CI, 0.95-1.49; P = .141). CONCLUSIONS: In patients undergoing noncardiac surgery, a MAP <55 mm Hg was associated with a duration-dependent increase in odds of postoperative delirium. This association was magnified in patients who underwent surgery of long duration.

Effect of Intraoperative Arterial Hypotension on the Risk of Perioperative Stroke After Noncardiac Surgery: A Retrospective Multicenter Cohort Study.

BACKGROUND: Intraoperative cerebral blood flow is mainly determined by cerebral perfusion pressure and cerebral autoregulation of vasomotor tone. About 1% of patients undergoing noncardiac surgery develop ischemic stroke. We hypothesized that intraoperative hypotension within a range frequently observed in clinical practice is associated with an increased risk of perioperative ischemic stroke within 7 days after surgery. METHODS: Adult noncardiac surgical patients undergoing general anesthesia at Beth Israel Deaconess Medical Center and Massachusetts General Hospital between 2005 and 2017 were included in this retrospective cohort study. The primary exposure was intraoperative hypotension, defined as a decrease in mean arterial pressure (MAP) below 55 mm Hg, categorized into no intraoperative hypotension, short (<15 minutes, median [interquartile range {IQR}], 2 minutes [1-5 minutes]) and prolonged (≥15 minutes, median [IQR], 21 minutes [17-31 minutes]) durations. The primary outcome was a new diagnosis of early perioperative ischemic stroke within 7 days after surgery. In secondary analyses, we assessed the effect of a MAP decrease by >30% from baseline on perioperative stroke. Analyses were adjusted for the preoperative STRoke After Surgery (STRAS) prediction score, work relative value units, and duration of surgery. RESULTS: Among 358,391 included patients, a total of 1553 (0.4%) experienced an early perioperative ischemic stroke. About 42% and 3% of patients had a MAP of below 55 mm Hg for a short and a prolonged duration, and 49% and 29% had a MAP decrease by >30% from baseline for a short and a prolonged duration, respectively. In an adjusted analysis, neither a MAP <55 mm Hg (short duration: adjusted odds ratio [ORadj], 0.95; 95% confidence interval [CI], 0.85-1.07; P = .417 and prolonged duration: ORadj, 1.18; 95% CI, 0.91-1.55; P = .220) nor a MAP decrease >30% (short duration: ORadj, 0.97; 95% CI, 0.67-1.42; P = .883 and prolonged duration: ORadj, 1.30; 95% CI, 0.89-1.90; P = .176) was associated with early perioperative stroke. A high a priori stroke risk quantified based on preoperatively available risk factors (STRAS prediction score) was associated with longer intraoperative hypotension (adjusted incidence rate ratio, 1.04; 95% CI, 1.04-1.05; P < .001 per 5 points of the STRAS prediction score). CONCLUSIONS: This study found no evidence to conclude that intraoperative hypotension within the range studied was associated with early perioperative stroke within 7 days after surgery. These findings emphasize the importance of perioperative cerebral blood flow autoregulation to prevent ischemic stroke.

Effects of Volatile Anesthetics on Postoperative Ischemic Stroke Incidence.

Background Preclinical studies suggest that volatile anesthetics decrease infarct volume and improve the outcome of ischemic stroke. This study aims to determine their effect during noncardiac surgery on postoperative ischemic stroke incidence. Methods and Results This was a retrospective cohort study of surgical patients undergoing general anesthesia at 2 tertiary care centers in Boston, MA, between October 2005 and September 2017. Exclusion criteria comprised brain death, age <18 years, cardiac surgery, and missing covariate data. The exposure was defined as median age-adjusted minimum alveolar concentration of all intraoperative measurements of desflurane, sevoflurane, and isoflurane. The primary outcome was postoperative ischemic stroke within 30 days. Among 314 932 patients, 1957 (0.6%) experienced the primary outcome. Higher doses of volatile anesthetics had a protective effect on postoperative ischemic stroke incidence (adjusted odds ratio per 1 minimum alveolar concentration increase 0.49, 95% CI, 0.40-0.59, P<0.001). In Cox proportional hazards regression, the effect was observed for 17 postoperative days (postoperative day 1: hazard ratio (HR), 0.56; 95% CI, 0.48-0.65; versus day 17: HR, 0.85; 95% CI, 0.74-0.99). Volatile anesthetics were also associated with lower stroke severity: Every 1-unit increase in minimum alveolar concentration was associated with a 0.006-unit decrease in the National Institutes of Health Stroke Scale (95% CI, -0.01 to -0.002, P=0.002). The effects were robust throughout various sensitivity analyses including adjustment for anesthesia providers as random effect. Conclusions Among patients undergoing noncardiac surgery, volatile anesthetics showed a dose-dependent protective effect on the incidence and severity of early postoperative ischemic stroke.

Adverse Outcomes Associated With Delaying or Withholding ß-Blockers After Cardiac Surgery: A Retrospective Single-Center Cohort Study.

BACKGROUND: Ideal timing of postoperative ß-blockers is unclear. We hypothesized that patients who do not receive ß-blockers immediately after cardiac surgery would have increased in-hospital mortality (primary outcome) and postoperative hemodynamic, pulmonary, neurologic, or respiratory complications (secondary outcomes). METHODS: We performed a retrospective cohort study evaluating patients who underwent cardiac surgery at our institution from January 1, 2013 to September 30, 2017. We compared outcomes between patients who received ß-blockers by postoperative day (POD) 5 with outcomes in patients who did not receive ß-blockers at any time or received them after POD 5. Inverse probability of treatment weighting was used to minimize confounding. Univariate logistic regression analyses were performed on the weighted sets using absent or delayed ß-blockers as the independent variable and each outcome as dependent variables in separate analyses. A secondary analysis was performed in patients prescribed preoperative ß-blockers. E-values were calculated for significant outcomes. RESULTS: All results were confounder adjusted. Among patients presenting for cardiac surgery, not receiving ß-blockers by POD 5 or at any time was not associated with the primary outcome in-hospital mortality, estimated odds ratio (OR; 99.5% confidence interval [CI]) of 1.6 (0.49-5.1), P = .28. Not receiving ß-blockers by POD 5 or at any time was associated with postoperative atrial fibrillation, estimated OR (99.5% CI) of 1.5 (1.1-2.1), P < .001, and pulmonary complications, estimated OR (99.5% CI) of 3.0 (1.8-5.2), P < .001. E-values were 2.4 for postoperative atrial fibrillation and 5.6 for pulmonary complications. Among patients presenting for cardiac surgery taking preoperative ß-blockers, not receiving ß-blockers by POD 5 or at any time was not associated with the primary outcome mortality, with estimated OR (99.5% CI) of 1.3 (0.43-4.1), P = .63. In this subset, not receiving ß-blockers by POD 5 or at any time was associated with increased adjusted ORs of postoperative atrial fibrillation (OR = 1.6; 99.5% CI, 1.1-2.4; P < .001) and postoperative pulmonary complications (OR = 2.8; 99.5% CI, 1.6-5.2; P < .001). Here, e-values were 2.7 for postoperative atrial fibrillation and 5.1 for pulmonary complications. For the sensitivity analyses for secondary outcomes, exposure and outcome periods overlap. Outcomes may have occurred before or after postoperative ß-blocker administration. CONCLUSIONS: Among patients who undergo cardiac surgery, not receiving postoperative ß-blockers within the first 5 days after cardiac surgery or at any time is not associated with in-hospital mortality and is associated with, but may not necessarily cause, postoperative atrial fibrillation and pulmonary complications.

Severity and duration of hypoxemia during outpatient endoscopy in obese patients: a retrospective cohort study.

PURPOSE: We sought to quantify the severity and duration of hypoxemic events in morbidly obese patients during outpatient endoscopy procedures performed under deep sedation. METHODS: This was a retrospective cohort study using intraprocedural pulse oximetry readings from 11,595 American Society of Anesthesiologists physical status score I-III adult patients who underwent deep sedation for elective endoscopy at free standing ambulatory centres between June 2015 and June 2016. Unadjusted and risk-adjusted logistic regression analyses explored the relationship between increasing categories of body mass index (BMI) and intraoperative hypoxemia, severe hypoxemia, and prolonged hypoxemia. RESULTS: Hypoxemia occurred in 600 (13%) patients with normal BMI, 314 (18%) with class I obesity, 159 (27%) with class II obesity, and 24 (19%) with class III obesity. Adjusted odds ratio (AOR) for any occurrence of intraoperative hypoxemia increased from 1.61 (95% confidence interval [CI], 1.35 to 1.90; P < 0.001) in the class I obesity group to 2.61 (95% CI, 2.05 to 3.30; P < 0.001) in patients with class II obesity, when compared with patients with normal BMI. Adjusted odds ratio of severe hypoxemia were significant in the class I obesity group (AOR, 1.47; 95% CI, 1.13 to 1.89; P = 0.003), and the class II obesity group (AOR, 2.59; 95% CI, 1.86 to 3.57; P < 0.001). Adjusted odds ratio of prolonged hypoxemia increased with each category of BMI from 1.97 (95% CI, 1.08 to 3.69) in the overweight group to 9.20 (95% CI, 4.74 to 18.03) in patients with class III obesity. CONCLUSIONS: The incidence of severe hypoxemia increased nearly six-fold in obese patients and 8.5-fold in class III obese patients when compared with those of normal BMI. Intravenous fentanyl was associated with intraoperative hypoxemia independent of BMI. Patients who represent the highest risk for hypoxia should be stratified to procedure locations with adequate resources for the safest care.

RéSUMé: OBJECTIF: Nous avons tenté de quantifier la gravité et la durée des complications hypoxémiques chez les patients obèses morbides pendant les interventions endoscopiques ambulatoires réalisées sous sédation profonde. MéTHODE: Nous avons réalisé une étude de cohorte rétrospective en nous fondant sur les relevés d'oxymétrie de pouls intra-procéduraux de 11 595 patients adultes de statut physique ASA (American Society of Anesthesiologists) I-III ayant subi une sédation profonde pour une endoscopie non urgente dans des centres ambulatoires indépendants entre juin 2015 et juin 2016. Les analyses de régression logistique non ajustées et ajustées en fonction du risque ont examiné la relation entre des catégories croissantes d'indice de masse corporelle (IMC) et l'hypoxémie, l'hypoxémie sévère et l'hypoxémie prolongée peropératoires. RéSULTATS: L'hypoxémie a touché 600 (13 %) patients ayant un IMC normal, 314 (18 %) patients souffrant d'une obésité de classe I, 159 (27 %) patients avec une obésité de classe II, et 24 (19 %) patients souffrant d'obésité de classe III. Le rapport de cotes ajusté (RCA) pour tout épisode d'hypoxémie peropératoire a augmenté de 1,61 (intervalle de confiance [IC] 95 %, 1,35 à 1,90; P < 0,001) dans le groupe obésité de classe I à 2,61 (IC 95 %, 2,05 à 3,30; P < 0,001) chez les patients présentant une obésité de classe II, par rapport aux patients avec un IMC normal. Les rapports de cotes ajustés pour l'hypoxémie sévère étaient significatifs dans le groupe de patients obèses de classe I (RCA, 1,47; IC 95 %, 1,13 à 1,89; P = 0,003) et dans le groupe de patients obèses de classe II (RCA, 2,59; IC 95 %, 1,86 à 3,57; P < 0,001). Les rapports de cotes ajustés pour l'hypoxémie prolongée ont augmenté avec chaque catégorie d'IMC, passant de 1,97 (IC 95 %, 1,08 à 3,69) dans le groupe en surcharge pondérale à 9,20 (IC 95 %, 4,74 à 18,03) chez les patients atteints d'obésité de classe III. CONCLUSION: L'incidence d'hypoxémie sévère a augmenté de près de six fois chez les patients obèses et de 8,5 fois chez les patients obèses de classe III par rapport aux patients ayant un IMC normal. L'administration intraveineuse de fentanyl était associée à une hypoxémie peropératoire indépendante de l'IMC. Les patients qui présentent le risque le plus élevé d'hypoxie devraient être stratifiés à être pris en charge dans des établissements disposant des ressources nécessaires pour offrir les soins les plus sécuritaires possibles.

Relationship Between Preoperative Antidepressant and Antianxiety Medications and Postoperative Hospital Length of Stay.

BACKGROUND: Patients on antidepressant or antianxiety medications often have complex perioperative courses due to difficult pain management, altered coping mechanisms, or medication-related issues. This study examined the relationship between preoperative antidepressants and antianxiety medications on postoperative hospital length of stay while controlling for confounding variables. METHODS: From an administrative database of 48,435 adult patients who underwent noncardiac surgery from 2011 to 2014 at a single, large urban academic institution, multivariable zero-truncated negative binomial regression analyses controlling for age, sex, medical comorbidities, and surgical type were performed to assess whether preoperative exposure to antidepressant or antianxiety medication use was associated with postoperative hospital length of stay. RESULTS: There were 5111 (10.5%) patients on antidepressants and 4912 (10.1%) patients on antianxiety medications. The median length of stay was 3 days (interquartile range = 2-6). After controlling for confounding variables, preoperative antidepressant medication was associated with increased length of stay with an incidence rate ratio of 1.04 (99% confidence interval, 1.0-1.08, P < .001) and antianxiety medication with an incidence rate ratio of 1.1 (99% confidence interval, 1.06-1.14; P < .001). CONCLUSIONS: The association between antidepressants or antianxiety medications and increased postoperative length of stay suggests that these patients may require greater attention in the perioperative period to hasten recovery, which may involve integrating preoperative counseling, postoperative psychiatric consults, or holistic recovery approaches into enhanced recovery protocols.

A retrospective study of opioid prescribing patterns at hospital discharge in surgical patients with obstructive sleep apnea.

PURPOSE: Obstructive sleep apnea (OSA) is a risk factor for complications with postoperative opioid use, and in those patients with known or suspected OSA, minimization of postoperative opioids is recommended. We hypothesize that despite these recommendations, surgical patients with known or suspected OSA are prescribed postoperative opioids at hospital discharge at similar doses to those without OSA. METHODS: This was a retrospective analysis of the electronic health records of surgical patients from 1 November 2016 to 30 April 2017 at a single academic institution. Patients with a known diagnosis of OSA or a STOP-Bang score ≥ 5 were compared with those without OSA for the amount of postoperative discharge opioid medication using multivariable linear regression. RESULTS: Of the 17,671 patients analyzed, 1,692 (9.6%) had known or suspected OSA with 1,450 (86%) of these patients discharged on opioid medications. Of the 15,979 patients without OSA, 12,273 (77%) were discharged on opioid medications. The total median [interquartile range (IQR)] oral morphine equivalents (OME) for all patients was 150 [0-338] mg and for patients with known or suspected OSA was 160 [0-450] mg, an unadjusted comparison showing an 18% difference in OME (95% confidence interval [CI], 3% to 35%; P = 0.02). The analysis, after adjusting for confounders, showed no significant difference in the amount of opioids prescribed to OSA or non-OSA patients (8% difference in total OME; 95% CI, -6% to 25%; P = 0.26). CONCLUSION: This study shows that surgical patients at risk for OSA or confirmed OSA are prescribed opioids at similar rates and doses upon discharge despite guidelines that recommend minimizing opioid use in OSA patients. These findings indicate a need to implement different strategies to reduce the prescription of opioids to patients with OSA.

Increasing body mass index and the incidence of intraoperative hypoxemia.

STUDY OBJECTIVE: Obese patients regularly present for surgery and have greater hypoxemia risk. This study aimed to identify the risk and incidence of intraoperative hypoxemia with increasing body mass index (BMI). DESIGN: This was a retrospective cohort study. SETTING: Operating room. PATIENTS: A total of 15,238 adult patients who underwent general anesthesia for elective noncardiac surgery at a single large urban academic institution between January 2013 and December 2014. INTERVENTIONS: Unadjusted and risk-adjusted logistic regression analyses explored the relationship between increasing categories of BMI and intraoperative hypoxemia, severe hypoxemia, and prolonged hypoxemia. MEASUREMENTS: Intraoperative pulse oximeter readings and preoperative patient characteristics. MAIN RESULTS: With normal BMI, 731 (16%) patients experienced hypoxemia compared with 1150 (28%) obese patients. Adjusted odds ratio (AOR) of intraoperative hypoxemia increased with each category of BMI from 1.27 (95% confidence interval [CI], 1.12-1.44) in overweight patients to 2.63 (95% CI, 2.15-3.23) in patients with class III obesity. AOR of severe hypoxemia was significant with class I obesity (AOR, 1.32; 95% CI, 1.08-1.60), class II obesity (AOR, 2.01; 95% CI, 1.59-2.81), and class III obesity (AOR, 2.27; 95% CI, 1.75-2.93). AOR of prolonged hypoxemia increased with BMI from 3.29 (95% CI, 1.79-6.23) with class I obesity to 9.20 (95% CI, 4.74-18) with class III obesity. CONCLUSIONS: Despite existing practices to limit hypoxemia in obese patients, the odds of experiencing intraoperative hypoxemia increase significantly with increasing categories of BMI. Further practices may need to be developed to minimize the risk of intraoperative hypoxemia in obese patients.

Preoperative Evaluation Clinic Visit Is Associated with Decreased Risk of In-hospital Postoperative Mortality.

BACKGROUND: As specialists in perioperative medicine, anesthesiologists are well equipped to design and oversee the preoperative patient preparation process; however, the impact of an anesthesiologist-led preoperative evaluation clinic (PEC) on clinical outcomes has yet to be fully elucidated. The authors compared the incidence of in-hospital postoperative mortality in patients who had been evaluated in their institution's PEC before elective surgery to the incidence in patients who had elective surgery without being seen in the PEC. METHODS: A retrospective review of an administrative database was performed. There were 46 deaths from 64,418 patients (0.07%): 22 from 35,535 patients (0.06%) seen in PEC and 24 from 28,883 patients (0.08%) not seen in PEC. After propensity score matching, there were 13,964 patients within each matched set; there were 34 deaths (0.1%). There were 11 deaths from 13,964 (0.08%) patients seen in PEC and 23 deaths from 13,964 (0.16%) patients not seen in PEC. A subanalysis to assess the effect of a PEC visit on deaths as a result of failure to rescue (FTR) was also performed. RESULTS: A visit to PEC was associated with a reduction in mortality (odds ratio, 0.48; 95% CI, 0.22 to 0.96, P = 0.04) by comparison of the matched cohorts. The FTR subanalysis suggested that the proportion of deaths attributable to an unanticipated surgical complication was not significantly different between the two groups (P = 0.141). CONCLUSIONS: An in-person assessment at the PEC was associated with a reduction in in-hospital mortality. It was difficult to draw conclusions about whether a difference exists in the proportion of FTR deaths between the two cohorts due to small sample size.