Association Between Anesthesiologist Sex and Patients' Postoperative Outcomes: A Population-based Cohort Study.

OBJECTIVE: To examine the association of anesthesiologist sex on postoperative outcomes. BACKGROUND: Differences in patient postoperative outcomes exist, depending on whether the primary surgeon is male or female, with better outcomes seen among patients treated by female surgeons. Whether the intraoperative anesthesiologist's sex is associated with differential postoperative patient outcomes is unknown. METHODS: We performed a population-based, retrospective cohort study among adult patients undergoing one of 25 common elective or emergent surgical procedures from 2007 to 2019 in Ontario, Canada. We assessed the association between the sex of the intraoperative anesthesiologist and the primary end point of the adverse postoperative outcome, defined as death, readmission, or complication within 30 days after surgery, using generalized estimating equations. RESULTS: Among 1,165,711 patients treated by 3006 surgeons and 1477 anesthesiologists, 311,822 (26.7%) received care from a female anesthesiologist and 853,889 (73.3%) from a male anesthesiologist. Overall, 10.8% of patients experienced one or more adverse postoperative outcomes, of whom 1.1% died. Multivariable adjusted rates of the composite primary end point were higher among patients treated by male anesthesiologists (10.6%) compared with female anesthesiologists (10.4%; adjusted odds ratio 1.02, 95% CI: 1.00-1.05, P =0.048). CONCLUSIONS: We demonstrated a significant association between sex of the intraoperative anesthesiologist and patient short-term outcomes after surgery in a large cohort study. This study supports the growing literature of improved patient outcomes among female practitioners. The underlying mechanisms of why outcomes differ between male and female physicians remain elusive and require further in-depth study.

Crosstalk between GABAA receptors in astrocytes and neurons triggered by general anesthetic drugs.

General anesthetic drugs cause cognitive deficits that persist after the drugs have been eliminated. Astrocytes may contribute to such cognition-impairing effects through the release of one or more paracrine factors that increase a tonic inhibitory conductance generated by extrasynaptic γ-aminobutyric acid type A (GABAA) receptors in hippocampal neurons. The mechanisms underlying this astrocyte-to-neuron crosstalk remain unknown. Interestingly, astrocytes express anesthetic-sensitive GABAA receptors. Here, we tested the hypothesis that anesthetic drugs activate astrocytic GABAA receptors to initiate crosstalk leading to a persistent increase in extrasynaptic GABAA receptor function in neurons. We also investigated the signaling pathways in neurons and aimed to identify the paracrine factors released from astrocytes. Astrocytes and neurons from mice were grown in primary cell cultures and studied using in vitro electrophysiological and biochemical assays. We discovered that the commonly used anesthetics etomidate (injectable) and sevoflurane (inhaled) stimulated astrocytic GABAA receptors, which in turn promoted the release paracrine factors, that increased the tonic current in neurons via a p38 MAPK-dependent signaling pathway. The increase in tonic current was mimicked by exogenous IL-1ß and abolished by blocking IL-1 receptors; however, unexpectedly, IL-1ß and other cytokines were not detected in astrocyte-conditioned media. In summary, we have identified a novel form of crosstalk between GABAA receptors in astrocytes and neurons that engages a p38 MAPK-dependent pathway. Brief commentary BACKGROUND: Many older patients experience cognitive deficits after surgery. Anesthetic drugs may be a contributing factor as they cause a sustained increase in the function of "memory blocking" extrasynaptic GABAA receptors in neurons. Interestingly, astrocytes are required for this increase; however, the mechanisms underlying the astrocyte-to-neuron crosstalk remain unknown. TRANSLATIONAL SIGNIFICANCE: We discovered that commonly used general anesthetic drugs stimulate GABAA receptors in astrocytes, which in turn release paracrine factors that trigger a persistent increase in extrasynaptic GABAA receptor function in neurons via p38 MAPK. This novel form of crosstalk may contribute to persistent cognitive deficits after general anesthesia and surgery.

Surgeon Sex and Health Care Costs for Patients Undergoing Common Surgical Procedures.

Importance: Prior research has shown differences in postoperative outcomes for patients treated by female and male surgeons. It is important to understand, from a health system and payer perspective, whether surgical health care costs differ according to the surgeon's sex. Objective: To examine the association between surgeon sex and health care costs among patients undergoing surgery. Design, Setting, and Participants: This population-based, retrospective cohort study included adult patients undergoing 1 of 25 common elective or emergent surgical procedures between January 1, 2007, and December 31, 2019, in Ontario, Canada. Analysis was performed from October 2022 to March 2023. Exposure: Surgeon sex. Main Outcome and Measure: The primary outcome was total health care costs assessed 1 year following surgery. Secondarily, total health care costs at 30 and 90 days, as well as specific cost categories, were assessed. Generalized estimating equations were used with procedure-level clustering to compare costs between patients undergoing equivalent surgeries performed by female and male surgeons, with further adjustment for patient-, surgeon-, anesthesiologist-, hospital-, and procedure-level covariates. Results: Among 1 165 711 included patients, 151 054 were treated by a female surgeon and 1 014 657 were treated by a male surgeon. Analyzed at the procedure-specific level and accounting for patient-, surgeon-, anesthesiologist-, and hospital-level covariates, 1-year total health care costs were higher for patients treated by male surgeons ($24 882; 95% CI, $20 780-$29 794) than female surgeons ($18 517; 95% CI, $16 080-$21 324) (adjusted absolute difference, $6365; 95% CI, $3491-9238; adjusted relative risk, 1.10; 95% CI, 1.05-1.14). Similar patterns were observed at 30 days (adjusted absolute difference, $3115; 95% CI, $1682-$4548) and 90 days (adjusted absolute difference, $4228; 95% CI, $2255-$6202). Conclusions and Relevance: This analysis found lower 30-day, 90-day, and 1-year health care costs for patients treated by female surgeons compared with those treated by male surgeons. These data further underscore the importance of creating inclusive policies and environments supportive of women surgeons to improve recruitment and retention of a more diverse and representative workforce.

Surgeon Sex and Long-Term Postoperative Outcomes Among Patients Undergoing Common Surgeries.

Importance: Sex- and gender-based differences in a surgeon's medical practice and communication may be factors in patients' perioperative outcomes. Patients treated by female surgeons have improved 30-day outcomes. However, whether these outcomes persist over longer follow-up has not been assessed. Objective: To examine whether surgeon sex is associated with 90-day and 1-year outcomes among patients undergoing common surgeries. Design, Setting, and Participants: A population-based retrospective cohort study was conducted in adults in Ontario, Canada, undergoing 1 of 25 common elective or emergent surgeries between January 1, 2007, and December 31, 2019. Analysis was performed between July 15 and October 20, 2022. Exposure: Surgeon sex. Main Outcomes and Measures: An adverse postoperative event, defined as the composite of death, readmission, or complication, was assessed at 90 days and 1 year following surgery. Secondarily, each of these outcomes was assessed individually. Outcomes were compared between patients treated by female and male surgeons using generalized estimating equations with clustering at the level of the surgical procedure, accounting for patient-, procedure-, surgeon-, anesthesiologist-, and facility-level covariates. Results: Among 1 165 711 included patients, 151 054 were treated by a female and 1 014 657 by a male surgeon. Overall, 14.3% of the patients had 1 or more adverse postoperative outcomes at 90 days and 25.0% had 1 or more adverse postoperative outcomes 1 year following surgery. Among these, 2.0% of patients died within 90 days and 4.3% died within 1 year. Multivariable-adjusted rates of the composite end point were higher among patients treated by male than female surgeons at both 90 days (13.9% vs 12.5%; adjusted odds ratio [AOR], 1.08; 95% CI, 1.03-1.13) and 1 year (25.0% vs 20.7%; AOR, 1.06; 95% CI, 1.01-1.12). Similar patterns were observed for mortality at 90 days (0.8% vs 0.5%; AOR 1.25; 95% CI, 1.12-1.39) and 1 year (2.4% vs 1.6%; AOR, 1.24; 95% CI, 1.13-1.36). Conclusions and Relevance: After accounting for patient, procedure, surgeon, anesthesiologist, and hospital characteristics, the findings of this cohort study suggest that patients treated by female surgeons have lower rates of adverse postoperative outcomes including death at 90 days and 1 year after surgery compared with those treated by male surgeons. These findings further support differences in patient outcomes based on physician sex that warrant deeper study regarding underlying causes and potential solutions.

Association Between Surgeon and Anesthesiologist Sex Discordance and Postoperative Outcomes: A Population-based Cohort Study.

OBJECTIVE: The aim of this study was to examine the effect of surgeon-anesthesiologist sex discordance on postoperative outcomes. SUMMARY BACKGROUND DATA: Optimal surgical outcomes depend on teamwork, with surgeons and anesthesiologists forming two key components. There are sex and sex-based differences in interpersonal communication and medical practice which may contribute to patients' perioperative outcomes. METHODS: We performed a population-based, retrospective cohort study among adult patients undergoing 1 of 25 common elective or emergent surgical procedures from 2007 to 2019 in Ontario, Canada. We assessed the association between differences in sex between surgeon and anesthesiologists (sex discordance) on the primary endpoint of adverse postoperative outcome, defined as death, readmission, or complication within 30 days following surgery using generalized estimating equations. RESULTS: Among 1,165,711 patients treated by 3006 surgeons and 1477 anesthesiologists, 791,819 patients were treated by sex concordant teams (male surgeon/male anesthesiologist: 747,327 and female surgeon/female anesthesiologist: 44,492), whereas 373,892 were sex discordant (male surgeon/female anesthesiologist: 267,330 and female surgeon/male anesthesiologist: 106,562). Overall, 12.3% of patients experienced >1 adverse postoperative outcomes of whom 1.3% died. Sex discordance between surgeon and anesthesiologist was not associated with a significant increased likelihood of composite adverse postoperative outcomes (adjusted odds ratio 1.00, 95% confidence interval 0.97-1.03). CONCLUSIONS: We did not demonstrate an association between intraoperative surgeon and anesthesiologist sex discordance on adverse postoperative outcomes in a large patient cohort. Patients, clinicians, and administrators may be reassured that physician sex discordance in operating room teams is unlikely to clinically meaningfully affect patient outcomes after surgery.

Sleep fragmentation, microglial aging, and cognitive impairment in adults with and without Alzheimer's dementia.

Sleep disruption is associated with cognitive decline and dementia in older adults; however, the underlying mechanisms are unclear. In rodents, sleep disruption causes microglial activation, inhibition of which improves cognition. However, data from humans are lacking. We studied participants in two cohort studies of older persons-the Rush Memory and Aging Project and the Religious Orders Study. We assessed sleep fragmentation by actigraphy and related this to cognitive function, to neocortical microglial marker gene expression measured by RNA sequencing, and to the neocortical density of microglia assessed by immunohistochemistry. Greater sleep fragmentation was associated with higher neocortical expression of genes characteristic of aged microglia, and a higher proportion of morphologically activated microglia, independent of chronological age- and dementia-related neuropathologies. Furthermore, these were, in turn, associated with worse cognition. This suggests that sleep fragmentation is accompanied by accelerated microglial aging and activation, which may partially underlie its association with cognitive impairment.

Dexmedetomidine Prevents Excessive γ-Aminobutyric Acid Type A Receptor Function after Anesthesia.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Postoperative delirium is associated with poor long-term outcomes and increased mortality. General anesthetic drugs may contribute to delirium because they increase cell-surface expression and function of α5 subunit-containing γ-aminobutyric acid type A receptors, an effect that persists long after the drugs have been eliminated. Dexmedetomidine, an α2 adrenergic receptor agonist, prevents delirium in patients and reduces cognitive deficits in animals. Thus, it was postulated that dexmedetomidine prevents excessive function of α5 γ-aminobutyric acid type A receptors. METHODS: Injectable (etomidate) and inhaled (sevoflurane) anesthetic drugs were studied using cultured murine hippocampal neurons, cultured murine and human cortical astrocytes, and ex vivo murine hippocampal slices. γ-Aminobutyric acid type A receptor function and cell-signaling pathways were studied using electrophysiologic and biochemical methods. Memory and problem-solving behaviors were also studied. RESULTS: The etomidate-induced sustained increase in α5 γ-aminobutyric acid type A receptor cell-surface expression was reduced by dexmedetomidine (mean ± SD, etomidate: 146.4 ± 51.6% vs. etomidate + dexmedetomidine: 118.4 ± 39.1% of control, n = 8 each). Dexmedetomidine also reduced the persistent increase in tonic inhibitory current in hippocampal neurons (etomidate: 1.44 ± 0.33 pA/pF, n = 10; etomidate + dexmedetomidine: 1.01 ± 0.45 pA/pF, n = 9). Similarly, dexmedetomidine prevented a sevoflurane-induced increase in the tonic current. Dexmedetomidine stimulated astrocytes to release brain-derived neurotrophic factor, which acted as a paracrine factor to reduce excessive α5 γ-aminobutyric acid type A receptor function in neurons. Finally, dexmedetomidine attenuated memory and problem-solving deficits after anesthesia. CONCLUSIONS: Dexmedetomidine prevented excessive α5 γ-aminobutyric acid type A receptor function after anesthesia. This novel α2 adrenergic receptor- and brain-derived neurotrophic factor-dependent pathway may be targeted to prevent delirium.

High Concentrations of Tranexamic Acid Inhibit Ionotropic Glutamate Receptors.

BACKGROUND: The antifibrinolytic drug tranexamic acid is structurally similar to the amino acid glycine and may cause seizures and myoclonus by acting as a competitive antagonist of glycine receptors. Glycine is an obligatory co-agonist of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Thus, it is plausible that tranexamic acid inhibits NMDA receptors by acting as a competitive antagonist at the glycine binding site. The aim of this study was to determine whether tranexamic acid inhibits NMDA receptors, as well as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate subtypes of ionotropic glutamate receptors. METHODS: Tranexamic acid modulation of NMDA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and kainate receptors was studied using whole cell voltage-clamp recordings of current from cultured mouse hippocampal neurons. RESULTS: Tranexamic acid rapidly and reversibly inhibited NMDA receptors (half maximal inhibitory concentration = 241 ± 45 mM, mean ± SD; 95% CI, 200 to 281; n = 5) and shifted the glycine concentration-response curve for NMDA-evoked current to the right. Tranexamic acid also inhibited α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (half maximal inhibitory concentration = 231 ± 91 mM; 95% CI, 148 to 314; n = 5 to 6) and kainate receptors (half maximal inhibitory concentration = 90 ± 24 mM; 95% CI, 68 to 112; n = 5). CONCLUSIONS: Tranexamic acid inhibits NMDA receptors likely by reducing the binding of the co-agonist glycine and also inhibits α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid and kainate receptors. Receptor blockade occurs at high millimolar concentrations of tranexamic acid, similar to the concentrations that occur after topical application to peripheral tissues. Glutamate receptors in tissues including bone, heart, and nerves play various physiologic roles, and tranexamic acid inhibition of these receptors may contribute to adverse drug effects.