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Background Overt stroke after non-cardiac surgery has a substantial impact on the duration and quality of life. Covert stroke in the non-surgical setting is much more common than overt stroke and is associated with an increased risk of cognitive decline and dementia. Little is known about covert stroke after non-cardiac, non-carotid artery surgery. Methods We undertook a prospective, international cohort study to determine the incidence of covert stroke after non-cardiac, non-carotid artery surgery. Eligible patients were ≥65 yr of age and were admitted to hospital for at least three nights after non-cardiac, non-carotid artery surgery. Patients underwent a brain magnetic resonance study between postoperative days 3 and 10. The main outcome was the incidence of perioperative covert stroke. Results We enrolled a total of 100 patients from six centres in four countries. The incidence of perioperative covert stroke was 10.0% (10/100 patients, 95% confidence interval 5.5–17.4%). Five of the six centres that enrolled patients reported an incident covert stroke, and covert stroke was found in patients undergoing major general (3/27), major orthopaedic (3/41), major urological or gynaecological (3/22), and low-risk surgery (1/12). Conclusions This international multicentre study suggests that 1 in 10 patients ≥65 yr of age experiences a perioperative covert stroke. A larger study is required to determine the impact of perioperative covert stroke on patient-important outcomes. Clinical trial registration NCT01369537.

Background Maximising patient comfort during and after surgery is a primary concern of anaesthetists and other perioperative clinicians, but objective measures of what constitutes patient comfort in the perioperative period remain poorly defined. The Standardised Endpoints in Perioperative Medicine initiative was established to derive a set of standardised endpoints for use in perioperative clinical trials. Methods We undertook a systematic review to identify measures of patient comfort used in the anaesthetic, surgical, and other perioperative literature. A multi-round Delphi consensus process that included up to 89 clinician researchers was then used to refine a recommended list of outcome measures. Results We identified 122 studies in a literature search, which were the basis for a preliminary list of 24 outcome measures and their definitions. The response rates for Delphi Rounds 1, 2, and 3 were 100% (n=22), 90% (n=79), and 100% (n=13), respectively. A final list of six defined endpoints was identified: pain intensity (at rest and during movement) at 24 h postoperatively, nausea and vomiting (0–6 h, 6–24 h, and overall), one of two quality-of-recovery (QoR) scales (QoR score or QoR-15), time to gastrointestinal recovery, time to mobilisation, and sleep quality. Conclusions As standardised outcomes will support benchmarking and pooling (meta-analysis) of trials, one or more of these recommended endpoints should be considered for inclusion in clinical trials assessing patient comfort and pain after surgery.

Objective To determine which bedside method of detecting inadvertent endobronchial intubation in adults has the highest sensitivity and specificity. Design Prospective randomised blinded study. Setting Department of anaesthesia in tertiary academic hospital. Participants 160 consecutive patients (American Society of Anesthesiologists category I or II) aged 19-75 scheduled for elective gynaecological or urological surgery. Interventions Patients were randomly assigned to eight study groups. In four groups, an endotracheal tube was fibreoptically positioned 2.5-4.0 cm above the carina, whereas in the other four groups the tube was positioned in the right mainstem bronchus. The four groups differed in the bedside test used to verify the position of the endotracheal tube. To determine whether the tube was properly positioned in the trachea, in each patient first year residents and experienced anaesthetists were randomly assigned to independently perform bilateral auscultation of the chest (auscultation); observation and palpation of symmetrical chest movements (observation); estimation of the position of the tube by the insertion depth (tube depth); or a combination of all three (all three). Main outcome measures Correct and incorrect judgments of endotracheal tube position. Results 160 patients underwent 320 observations by experienced and inexperienced anaesthetists. First year residents missed endobronchial intubation by auscultation in 55% of cases and performed significantly worse than experienced anaesthetists with this bedside test (odds ratio 10.0, 95% confidence interval 1.4 to 434). With a sensitivity of 88% (95% confidence interval 75% to 100%) and 100%, respectively, tube depth and the three tests combined were significantly more sensitive for detecting endobronchial intubation than auscultation (65%, 49% to 81%) or observation(43%, 25% to 60%) (P

We used a complex computer model of human thermal behavior to simulate the human thermal responses to epidural anesthesia. The circulatory changes that accompany onset of sympathetic blockade were modelled by forcing blood flow in the lower extremities to increase to 300% of baseline. Model responses were compared to those measured in five human volunteers in whom epidural anesthesia was induced. The model responses for average skin temperature, central temperature and cutaneous heat loss closely resembled those measured in volunteers. The human thermal model provides a convenient tool for investigating the mechanisms of anestheticrelated hypothermia.

Redistribution of heat from the core to the cool peripheral compartments of the body causes hypothermia during epidural anesthesia. Diminishing the temperature gradient between the core and peripheral tissues by warming the body via the skin before anesthesia should prevent this hypothermia. We measured core temperature, skin temperatures, and cutaneous heat loss in seven volunteers who received two lidocaine epidural injections during a single study day. One epidural injection was given after the volunteer had rested in a cool room (approximately 22 degrees C) ("no prewarming") for 2 h, and one injection was given after the volunteer had been covered with a forced air warming mattress (approximately 38 degrees C) ("prewarming") for 2 h. Skin temperatures were higher after prewarming. The decrease in core temperature during epidural anesthesia was smaller after prewarming [mean within patient difference (prewarming-no prewarming): 0.41; P = 0.003]. However, heat loss was greater after prewarming (mean within patient difference: 26.4; P = 0.02). Shivering was less after prewarming. We conclude that prewarming decreases redistribution hypothermia caused by epidural block. These results support the hypothesis that redistribution of heat within the body, not heat loss, is the most important etiology of hypothermia from epidural anesthesia.