Driving performance of outpatients achieving discharge criteria after deep sedation is worse than these of their escort-driver: a prospective observational study on simulator.

Background: Achieving post-anesthesia discharge criteria after surgery or outpatient procedures does not mean that the patient has regained all his or her faculties, such as driving. Although mandated by many clinical guidelines, there is no evidence that escort-drivers reduce the risk of traffic accidents after deep sedation. The purpose of this study was to evaluate that hypothesis that driving performance as measured using a driving simulation would not differ between patients who had undergone deep sedation for gastrointestinal endoscopy meeting discharge criteria and their escorts. Methods: This prospective study included patients scheduled for ambulatory gastrointestinal endoscopy under deep propofol sedation (patient group) and their escorts (escort group). Driving performance of escorts and patients (when discharge criteria were met) was assessed using a driving simulator. Results: 30 patients and their escorts were included. Patients crossed the midline significantly more frequently than escorts (3 [2-4] (median [IQR]) and 2 [1-3] crossings, respectively, p=0.015]. Patients were speeding for a higher proportion of the distance traveled compared with escorts (37 (20)% (mean (SD)) and 24 (17)% in patients and escorts, respectively, p = 0.029). There were no significant differences between groups in other simulation parameters. Conclusions: The ability to stay within the traffic lanes, as measured by the number of midline crossing during a simulated driving performance, is impaired in patients who meet discharge criteria after gastrointestinal endoscopy under deep sedation compared with their escorts. This finding does not support a practice of allowing patients to drive themselves home after these procedures.

Association between exposure to anaesthesia and surgery and long-term cognitive trajectories in older adults: report from the Mayo Clinic Study of Aging.

BACKGROUND: The link between exposure to general anaesthesia and surgery (exposure) and cognitive decline in older adults is debated. We hypothesised that it is associated with cognitive decline. METHODS: We analysed the longitudinal cognitive function trajectory in a cohort of older adults. Models assessed the rate of change in cognition over time, and its association with exposure to anaesthesia and surgery. Analyses assessed whether exposure in the 20 yr before enrolment is associated with cognitive decline when compared with those unexposed, and whether post-enrolment exposure is associated with a change in cognition in those unexposed before enrolment. RESULTS: We included 1819 subjects with median (25th and 75th percentiles) follow-up of 5.1 (2.7-7.6) yr and 4 (3-6) cognitive assessments. Exposure in the previous 20 yr was associated with a greater negative slope compared with not exposed (slope: -0.077 vs -0.059; difference: -0.018; 95% confidence interval: -0.032, -0.003; P=0.015). Post-enrolment exposure in those previously unexposed was associated with a change in slope after exposure (slope: -0.100 vs -0.059 for post-exposure vs pre-exposure, respectively; difference: -0.041; 95% confidence interval: -0.074, -0.008; P=0.016). Cognitive impairment could be attributed to declines in memory and attention/executive cognitive domains. CONCLUSIONS: In older adults, exposure to general anaesthesia and surgery was associated with a subtle decline in cognitive z-scores. For an individual with no prior exposure and with exposure after enrolment, the decline in cognitive function over a 5 yr period after the exposure would be 0.2 standard deviations more than the expected decline as a result of ageing. This small cognitive decline could be meaningful for individuals with already low baseline cognition.

What do recent human studies tell us about the association between anaesthesia in young children and neurodevelopmental outcomes?

Anaesthetic and sedative drugs transiently disrupt normal neural activity to facilitate healthcare procedures in children, but they can also cause long-term brain injury in experimental animal models. The US Food and Drug Administration (FDA) has recently advised that repeated or lengthy exposures to anaesthetic and sedative drugs prior to 3 yr of age have the potential to harm the development of children's brains and added warnings to these drug labels. Paediatric anaesthesia toxicity could represent a significant public health issue, and concern about this potential injury in children has become an important issue for families, paediatric clinicians and healthcare regulators. Since late 2015, important new data from five major clinical studies have been published. This narrative review aims to provide a brief overview of the preclinical and clinical literature, including a comprehensive review of these recent additions to the human literature. We integrate these new data with prior studies to provide further insights into how these clinical findings can be applied to children.

Postoperative delirium in elderly patients is associated with subsequent cognitive impairment.

BACKGROUND: We examined the risk for postoperative delirium (POD) in patients with mild cognitive impairment (MCI) or dementia, and the association between POD and subsequent development of MCI or dementia in cognitively normal elderly patients. METHODS: Patients ≥65 yr of age enrolled in the Mayo Clinic Study of Aging who were exposed to any type of anaesthesia from 2004 to 2014 were included. Cognitive status was evaluated before and after surgery by neuropsychological testing and clinical assessment, and was defined as normal or MCI/dementia. Postoperative delirium was detected with the Confusion Assessment Method for the intensive care unit. Logistic regression analyses were performed. RESULTS: Among 2014 surgical patients, 74 (3.7%) developed POD. Before surgery, 1667 participants were cognitively normal, and 347 met MCI/dementia criteria. The frequency of POD was higher in patients with pre-existing MCI/dementia compared with no MCI/dementia {8.7 vs 2.6%; odds ratio (OR) 2.53, [95% confidence interval (CI) 1.52-4.21]; P <0.001}. Postoperative delirium was associated with lower education [OR, 3.40 (95% CI, 1.60-7.40); P =0.002 for those with <12 vs ≥16 yr of schooling]. Of the 1667 patients cognitively normal at their most recent assessment, 1152 returned for postoperative evaluation, and 109 (9.5%) met MCI/dementia criteria. The frequency of MCI/dementia at the first postoperative evaluation was higher in patients who experienced POD compared with those who did not [33.3 vs 9.0%; adjusted OR, 3.00 (95% CI, 1.12-8.05); P =0.029]. CONCLUSIONS: Mild cognitive impairment or dementia is a risk for POD. Elderly patients who have not been diagnosed with MCI or dementia but experience POD are more likely to be diagnosed subsequently with MCI or dementia.

Obstructive sleep apnoea and perioperative complications in bariatric patients.

BACKGROUND: The objective of this study was to determine the relationship between perioperative complications and the severity of obstructive sleep apnoea (OSA) in patients undergoing bariatric surgery who had undergone preoperative polysomnography (PSG). METHODS: The records of 797 patients, age >18 yr, who underwent bariatric operations (442 open and 355 laparoscopic procedures) at Mayo Clinic and were assessed before operation by PSG, were reviewed retrospectively. OSA was quantified using the apnoea-hypopnoea index (AHI) as none (≤ 4), mild (5-15), moderate (16-30), and severe (≥ 31). Pulmonary, surgical, and 'other' complications within the first 30 postoperative days were analysed according to OSA severity. Logistic regression was used to assess the multivariable association of OSA, age, sex, BMI, and surgical approach with postoperative complications. RESULTS: Most patients with OSA (93%) received perioperative positive airway pressure therapy, and all patients were closely monitored after operation with pulse oximetry on either regular nursing floors or in intensive or intermediate care units. At least one postoperative complication occurred in 259 patients (33%). In a multivariable model, the overall complication rate was increased with open procedures compared with laparoscopic. In addition, increased BMI and age were associated with increased likelihood of pulmonary and other complications. Complication rates were not associated with OSA severity. CONCLUSIONS: In obese patients evaluated before operation by PSG before bariatric surgery and managed accordingly, the severity of OSA, as assessed by the AHI, was not associated with the rate of perioperative complications. These results cannot determine whether unrecognized and untreated OSA increases risk.

Comparison of two ventilatory strategies in elderly patients undergoing major abdominal surgery.

BACKGROUND: 'Open lung' ventilation is commonly used in patients with acute lung injury and has been shown to improve intraoperative oxygenation in obese patients undergoing laparoscopic surgery. The feasibility of an 'open lung' ventilatory strategy in elderly patients under general anaesthesia has not previously been assessed. METHODS: 'Open lung' ventilation (recruitment manoeuvres, tidal volume 6 ml kg(-1) predicted body weight, and 12 cm H(2)O PEEP) (RM group) was compared with conventional ventilation (no recruitment manoeuvres, tidal volume 10 ml kg(-1) predicted body weight, and zero end-expiratory pressure) in elderly patients (>65 yr) undergoing major open abdominal surgery with regard to oxygenation, respiratory system mechanics, and haemodynamic stability. We also monitored the serum levels of the interleukins (IL)-6 and IL-8 before and after surgery to determine whether the systemic inflammatory response to surgery depends on the ventilatory strategy used. RESULTS: Twenty patients were included in each group. The RM group tolerated open lung ventilation without significant haemodynamic instability. Intraoperative Pa(o(2)) improved in the RM group (P<0.01) and deteriorated in controls (P=0.01), but postoperative Pa(o(2)) was similar in both groups. The RM group had improved breathing mechanics as evidenced by increased dynamic compliance (36%) and decreased airway resistance (21%). Both IL-6 and IL-8 significantly increased after surgery, but the magnitude of increase did not differ between the groups. CONCLUSIONS: A lung recruitment strategy in elderly patients is well tolerated and improves intraoperative oxygenation and lung mechanics during laparotomy.

Intraoperative ventilator settings and acute lung injury after elective surgery: a nested case control study.

BACKGROUND: While acute lung injury (ALI) is among the most serious postoperative pulmonary complications, its incidence, risk factors and outcome have not been prospectively studied. OBJECTIVE: To determine the incidence and survival of ALI associated postoperative respiratory failure and its association with intraoperative ventilator settings, specifically tidal volume. DESIGN: Prospective, nested, case control study. SETTING: Single tertiary referral centre. PATIENTS: 4420 consecutive patients without ALI undergoing high risk elective surgeries for postoperative pulmonary complications. MEASUREMENTS: Incidence of ALI, survival and 2:1 matched case control comparison of intraoperative exposures. RESULTS: 238 (5.4%) patients developed postoperative respiratory failure. Causes included ALI in 83 (35%), hydrostatic pulmonary oedema in 74 (31%), shock in 27 (11.3%), pneumonia in nine (4%), carbon dioxide retention in eight (3.4%) and miscellaneous in 37 (15%). Compared with match controls (n = 166), ALI cases had lower 60 day and 1 year survival (99% vs 73% and 92% vs 56%; p<0.001). Cases were more likely to have a history of smoking, chronic obstructive pulmonary disease and diabetes, and to be exposed to longer duration of surgery, intraoperative hypotension and larger amount of fluid and transfusions. After adjustment for non-ventilator parameters, mean first hour peak airway pressure (OR 1.07; 95% CI 1.02 to 1.15 cm H(2)O) but not tidal volume (OR 1.03; 95% CI 0.84 to 1.26 ml/kg), positive end expiratory pressure (OR 0.89; 95% CI 0.77 to 1.04 cm H(2)O) or fraction of inspired oxygen (OR 1.0; 95% CI 0.98 to 1.03) were associated with ALI. CONCLUSION: ALI is the most common cause of postoperative respiratory failure and is associated with markedly lower postoperative survival. Intraoperative tidal volume was not associated with an increased risk for early postoperative ALI.

Perioperative tobacco use interventions in Japan: a survey of thoracic surgeons and anaesthesiologists.

BACKGROUND: Tobacco use interventions in surgical patients who smoke could benefit both their short-term outcome and long-term health. Anaesthesiologists and surgeons can play key roles in delivering these interventions. This study determined the practices, attitudes, and beliefs of these physicians regarding tobacco use interventions in Japan. METHODS: Questionnaires were mailed to a national random sampling of Japanese anaesthesiologists and thoracic surgeons (1000 in each group). RESULTS: The survey response rate was 62%. More than 80% of respondents agreed or strongly agreed with the statements affirming the benefits of abstinence to surgical patients. However, only 26% of surgeons and 6% of anaesthesiologists reported almost always providing help to their patients to quit smoking. Compared with anaesthesiologists, surgeons were more likely to perform the elements of current recommendations for brief intervention, and to have attitudes favourable to tobacco use interventions. The most significant barrier to intervention identified by both groups was a lack of time to perform counselling. Compared with non-smokers, physicians who smoked were less likely to perform each of the recommended tobacco interventions CONCLUSIONS: Although current rates of intervention provided by anaesthesiologists and surgeons are low, there is considerable interest among these physicians in learning more about interventions. Given the relatively high prevalence of smoking in Japan and the potential for surgery to serve as a 'teachable moment' to promote abstinence from smoking, leadership by these specialists in the area of tobacco control could have a major impact on public health in Japan.

The frequency of perioperative vision loss.

UNLABELLED: The frequency of perioperative vision loss, especially for spinal surgery, has been increasing recently. We undertook a retrospective study to determine the frequency of this outcome in a large surgical population receiving general or central neuraxis regional anesthesia for noncardiac procedures from 1986 to 1998. Specific criteria were used to separate cases in which the surgical procedure likely directly contributed to the vision loss. Vision loss was present if any part of the visual field was affected. Initial database screening found 405 cases of new-onset vision loss or visual changes in 410,189 patients who underwent 501,342 anesthetics and who survived at least 30 days after their final procedures. Two hundred sixteen of these patients regained full vision or acuity within 30 days. Of the 189 patients who developed vision deficits for longer than 30 days, 185 underwent ophthalmologic or neurologic procedures in which ocular or cerebral tissues were surgically damaged or resected. The remaining 4 patients (1 per 125,234 overall; 0.0008%) developed prolonged vision loss without direct surgical trauma to optic or cerebral tissues. In this large study population of noncardiac surgical patients, including those who underwent spinal surgical procedures, the frequency of perioperative vision loss persisting for longer than 30 days was very small. IMPLICATIONS: Vision loss and blindness after surgery and anesthesia is a very rare event. In this study, only one per 125,234 patients undergoing noncardiac surgery developed vision loss persisting for longer than 30 days.

Calcium sensitization produced by G protein activation in airway smooth muscle.

We determined whether activation of G proteins can affect the force developed for a given intracellular Ca(2+) concentration ([Ca(2+)]; i.e., the Ca(2+) sensitivity) by mechanisms in addition to changes in regulatory myosin light chain (rMLC) phosphorylation. Responses in alpha-toxin-permeabilized canine tracheal smooth muscle were determined with Ca(2+) alone or in the presence of ACh, endothelin-1 (ET-1), or aluminum fluoride (AlF; acute or 1-h exposure). Acute exposure to each compound increased Ca(2+) sensitivity without changing the response to high [Ca(2+)] (maximal force). However, chronic exposure to AlF, but not to chronic ACh or ET-1, increased maximal force by increasing the force produced for a given rMLC phosphorylation. Studies employing thiophosphorylation of rMLC showed that the increase in force produced by chronic AlF exposure required Ca(2+) during activation to be manifest. Unlike the acute response to receptor agonists, which is mediated solely by increases in rMLC phosphorylation, chronic direct activation of G proteins further increases Ca(2+) sensitivity in airways by additional mechanisms that are independent of rMLC phosphorylation.

Effects of halothane on sarcoplasmic reticulum calcium release channels in porcine airway smooth muscle cells.

BACKGROUND: Volatile anesthetics relax airway smooth muscle (ASM) by altering intracellular Ca2+ concentration ([Ca2+]i). The authors hypothesized that relaxation is produced by decreasing sarcoplasmic reticulum Ca2+ content via increased Ca2+ "leak" through both inositol trisphosphate (IP3) and ryanodine receptor channels. METHODS: Enzymatically dissociated porcine ASM cells were exposed to acetylcholine in the presence or absence of 2 minimum alveolar concentration (MAC) halothane, and IP3 levels were measured using radioimmunoreceptor assay. Other cells were loaded with the Ca2+ indicator fluo-3 and imaged using real-time confocal microscopy. RESULTS: Halothane increased IP3 concentrations in the presence and absence of acetylcholine. Inhibition of phospholipase C blunted the IP3 response to halothane. Exposure to 2 MAC halothane induced a transient [Ca2+]i response, suggesting depletion of sarcoplasmic reticulum Ca2+. Exposure to 20 microM Xestospongin D, a cell-permeant IP3 receptor antagonist, resulted in a 45+/-13% decrease in the [Ca2+]i response to halothane compared with halothane exposure alone. In permeabilized cells, Xestospongin D or 0.5 mg/ml heparin decreased the [Ca2+]i response to halothane by 65+/-13% and 68+/-22%, respectively, compared with halothane alone. In both intact and permeabilized cells, 20 microM ryanodine blunted the [Ca2+]i response to halothane by 32+/-13% and 39+/-21%, respectively, compared with halothane alone. Simultaneous exposure to Xestospongin D and ryanodine completely inhibited the [Ca2+]i response to halothane. CONCLUSIONS: The authors conclude that halothane reduces sarcoplasmic reticulum Ca2+ content in ASM cells via increased Ca2+ leak through both IP3 receptor and ryanodine receptor channels. Effects on IP3 receptor channels are both direct and indirect via elevation of IP3 levels.

The effects of ethanol on CA(2+) sensitivity in airway smooth muscle.

UNLABELLED: Halothane and other volatile anesthetics relax air-way smooth muscle (ASM) in part by decreasing the amount of force produced for a given intracellular Ca(2+) concentration (the Ca(2+) sensitivity) during muscarinic receptor stimulation. To determine whether this is a unique property of the volatile anesthetics, we tested the hypothesis that ethanol, another compound with anesthetic properties, also inhibits calcium sensitization induced by muscarinic stimulation of ASM. A beta-escin permeabilized canine tracheal smooth muscle preparation was used. Ethanol was applied to permeabilized muscles stimulated with calcium in either the absence or presence of acetylcholine. In intact ASM, ethanol produced incomplete relaxation (approximately 40%) at concentrations up to 300 mM. Ethanol significantly increased Ca(2+) sensitivity both in the presence and the absence of muscarinic receptor stimulation. Although ethanol did not affect regulatory myosin light chain (rMLC) phosphorylation during stimulation with Ca(2+) alone, it decreased rMLC phosphorylation by Ca(2+) during muscarinic receptor stimulation. Ethanol, like volatile anesthetics, inhibits increases in rMLC phosphorylation produced by muscarinic receptor stimulation at constant [Ca(2+)](i). However, despite this inhibition, the net effect of ethanol is to increase Ca(2+) sensitivity (defined as the force maintained for a given [Ca(2+)](i)) by a mechanism that is independent of changes in rMLC phosphorylation. IMPLICATIONS: In permeabilized airway smooth muscle, ethanol, like volatile anesthetics, inhibits increases in regulatory protein phosphorylation caused by stimulation of the muscle when intracellular calcium concentration is constant. However, unlike volatile anesthetics, ethanol causes a net increase in force through a process not dependent on protein phosphorylation, an action favoring bronchoconstriction.

Halothane increases smooth muscle protein phosphatase in airway smooth muscle.

BACKGROUND: Halothane relaxes airway smooth muscle, in part, by decreasing the force produced for a given intracellular [Ca(2+)] (i.e., Ca(2+) sensitivity) during muscarinic stimulation, an effect produced by a decrease in regulatory myosin light-chain (rMLC) phosphorylation. The authors tested the hypothesis that halothane reduces rMLC phosphorylation during muscarinic stimulation at constant intracellular [Ca(2+)] by increasing smooth muscle protein phosphatase (SMPP) activity, without changing myosin light-chain kinase (MLCK) activity. METHODS: Enzyme activities were assayed in beta-escin permeabilized strips of canine tracheal smooth muscle. Under conditions of constant intracellular [Ca(2+)], the rate of rMLC phosphorylation was measured by Western blotting during inhibition of SMPP with microcystin-LR (to assay MLCK activity) or during inhibition of MLCK by wortmannin and adenosine triphosphate depletion (to assay SMPP activity). The effect of halothane (0.8 mm) on enzyme activities and isometric force during stimulation with 0.6 microm Ca(2+) and 10 microm acetylcholine was determined. RESULTS: Halothane produced a 14 +/- 8% (mean +/- SD) decrease in isometric force by significantly reducing rMLC phosphorylation (from 32 +/- 9% to 28 +/- 9%). Halothane had no significant effect on any parameter of a monoexponential relation fit to the data for the MLCK activity assay. In contrast, halothane significantly decreased the half-time for rMLC dephosphorylation in the SMPP activity assay (from 0.74 +/- 0.28 min to 0.44 +/- 0.10 min), indicating that it increased SMPP activity. CONCLUSIONS: Halothane decreases Ca(2+) sensitivity and rMLC phosphorylation in airway smooth muscle during muscarinic receptor stimulation by increasing SMPP activity, without affecting MLCK, probably by disrupting receptor G-protein signaling pathways that inhibit SMPP.

Lower extremity neuropathies associated with lithotomy positions.

BACKGROUND: The goal of this project was to study the frequency and natural history of perioperative lower extremity neuropathies. METHODS: A prospective evaluation of lower extremity neuropathies in 991 adult patients undergoing general anesthetics and surgical procedures while positioned in lithotomy was performed. Patients were assessed with use of a standard questionnaire and neurologic examination before surgery, daily during hospital stay in the first week after surgery, and by phone if discharged before 1 postoperative week. Patients in whom lower extremity neuropathies developed were observed for 6 months. RESULTS: Lower extremity neuropathies developed in 15 patients (1.5%; 95% confidence interval, 0.8-2.5%). Unilateral or bilateral nerves were affected in patients as follows: obturator (five patients), lateral femoral cutaneous (four patients), sciatic (three patients), and peroneal (three patients). Paresthesia occurred in 14 of 15 patients, and 4 patients had burning or aching pain. No patient had weakness. Symptoms were noted within 4 h of completion of the anesthetic in all 15 patients. These symptoms resolved within 6 months in 14 of 15 patients. Prolonged positioning in a lithotomy position, especially for more than 2 h, was a major risk factor for this complication (P = 0.006). CONCLUSIONS: In this surgical population, lower extremity neuropathies were infrequent complications that were noted very soon after surgery and anesthesia. None resulted in prolonged disability. The longer patients were positioned in lithotomy positions, the greater the chance of development of a neuropathy. These findings suggest that a reduction of duration of time in lithotomy positions may reduce the risk of lower extremity neuropathies.

Relationship between force and regulatory myosin light chain phosphorylation in airway smooth muscle.

We tested the hypothesis that increases in force at a given cytosolic Ca(2+) concentration (i.e., Ca(2+) sensitization) produced by muscarinic stimulation of canine tracheal smooth muscle (CTSM) are produced in part by mechanisms independent of changes in regulatory myosin light chain (rMLC) phosphorylation. This was accomplished by comparing the relationship between rMLC phosphorylation and force in alpha-toxin-permeabilized CTSM in the absence and presence of acetylcholine (ACh). Forces were normalized to the contraction induced by 10 microM Ca(2+) in each strip, and rMLC phosphorylation is expressed as a percentage of total rMLC. ACh (100 microM) plus GTP (1 microM) significantly shifted the Ca(2+)-force relationship curve to the left (EC(50): 0.39 +/- 0.06 to 0.078 +/- 0.006 microM Ca(2+)) and significantly increased the maximum force (104.4 +/- 4.8 to 120.2 +/- 2.8%; n = 6 observations). The Ca(2+)-rMLC phosphorylation relationship curve was also shifted to the left (EC(50): 1.26 +/- 0.57 to 0.13 +/- 0.04 microM Ca(2+)) and upward (maximum rMLC phosphorylation: 70.9 +/- 7.9 to 88.5 +/- 5. 1%; n = 6 observations). The relationships between rMLC phosphorylation and force constructed from mean values at corresponding Ca(2+) concentrations were not different in the presence and absence of ACh. We find no evidence that muscarinic stimulation increases Ca(2+) sensitivity in CTSM by mechanisms other than increases in rMLC phosphorylation.

S-nitrosoglutathione-induced decrease in calcium sensitivity of airway smooth muscle.

The purpose of this study was to examine whether the nitric oxide donor S-nitrosoglutathione (GSNO) relaxes canine tracheal smooth muscle (CTSM) strips by decreasing Ca(2+) sensitivity [i.e., the amount of force for a given intracellular Ca(2+) concentration ([Ca(2+)](i))]. We further investigated whether GSNO decreases Ca(2+) sensitivity by altering the relationship between regulatory myosin light chain (rMLC) phosphorylation and [Ca(2+)](i) and the relationship between force and rMLC phosphorylation. GSNO (100 microM) relaxed intact CTSM strips contracted with 45 mM KCl by decreasing Ca(2+) sensitivity in comparison to control strips without significantly decreasing [Ca(2+)](i). GSNO reduced the amount of rMLC phosphorylation for a given [Ca(2+)](i) but did not affect the relationship between isometric force and rMLC phosphorylation. These results show that in CTSM strips contracted with KCl, GSNO decreases Ca(2+) sensitivity by affecting the level of rMLC phosphorylation for a given [Ca(2+)](i), suggesting that myosin light chain kinase is inhibited or that smooth muscle protein phosphatases are activated by GSNO.

Risk of surgery and anesthesia for ischemic stroke.

BACKGROUND: The goal of this study was to determine if the combination of surgery and anesthesia is an independent risk factor for the development of incident (first-time) ischemic stroke. METHODS: All residents of Rochester, MN, with incident ischemic stroke from 1960 through 1984 (1,455 cases and 1,455 age- and gender-matched controls) were used to identify risk factors associated with ischemic stroke. Cases and controls undergoing surgery involving general anesthesia or central neuroaxis blockade before their stroke/index date of diagnosis were identified. A conditional logistic regression model was used to estimate the odds ratio of surgery and anesthesia for ischemic stroke while adjusting for other known risk factors. RESULTS: There were 59 cases and 17 controls having surgery within 30 days before their stroke/index date. After adjusting for previously identified risk factors, surgery within 30 days before the stroke/index date (perioperative period) was found to be an independent risk factor for stroke (P<0.001; odds ratio, 3.9; 95% confidence interval, 2.1-7.4). In an analysis that excluded matched pairs where the case and/or control underwent surgery considered "high risk" for stroke (cardiac, neurologic, or vascular procedures), "non-high-risk surgery" was also found to be an independent risk factor for perioperative stroke (P = 0.002; odds ratio, 2.9; 95% confidence interval, 1.5-5.7). CONCLUSION: Our results suggest that there is an increased risk of ischemic stroke in the 30 days after surgery and anesthesia. This risk remains elevated even after excluding surgeries (cardiac, neurologic, and vascular surgeries) considered to be high risk for ischemic stroke.