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Harsha Shanthanna,1 Alparslan Turan,2 Jessica Vincent,3 Remie Saab,2 Yaron Shargall,4 Turlough O’Hare,1 Kimberly Davis,5 Sylvanus Fonguh,3 Kumar Balasubramaniam,3 James Paul,1 Ian Gilron,6 Henrik Kehlet,7 Daniel I Sessler,2 Mohit Bhandari,8 Lehana Thabane,9 PJ Devereaux9 1Department of Anesthesia, McMaster University, Hamilton, ON, Canada; 2Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic, Cleveland, OH, USA; 3Population Health Research Institute, Hamilton, ON, Canada; 4Department of Surgery, St Joseph’s Healthcare Hamilton, Hamilton, ON, Canada; 5Acute Pain Service, St. Joseph Healthcare Hamilton, Hamilton, ON, Canada; 6Departments of Anesthesiology and Perioperative Medicine, Biomedical and Molecular Sciences, Centre for Neuroscience Studies and School of Policy Studies, Queen’s University, Kingston, ON, Canada; 7Section of Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark; 8Department of Surgery, McMaster University, Hamilton, ON, Canada; 9Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, ON, CanadaCorrespondence: Harsha ShanthannaDepartment of Anesthesia, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, CanadaTel +1 905-525-9140 ext. 21737Fax +1 905-523-1224Email shanthh@mcmaster.caPurpose: We conducted a feasibility 2× 2 factorial trial comparing N-methyl-D-aspartate (NMDA) antagonists (intravenous ketamine and oral memantine) versus placebo and intravenous steroids versus placebo, in patients having elective video-assisted thoracic surgery lobectomies, at St. Joseph’s Hamilton, Canada, and Cleveland Clinic, Cleveland, USA. Our feasibility objectives were: 1) recruitment rate/week; 2) recruitment of ≥ 90% of eligible patients; and 3) > 90% follow-up. Secondary objectives were incidence and intensity of persistent post-surgical pain (PPSP) and other clinical and safety outcomes.Methods: Using computerized randomization, patients were allocated to one of four groups: NMDA active with steroid placebo; NMDA placebo with steroid active; both NMDA and steroid active; both NMDA and steroid placebo. Patients, health providers, and data analysts were blinded to allocation. Patients were followed for 3 months after randomization.Results: The trial was initiated in May 2017 at Hamilton and, after subsequent regulatory and ethics approval, in April 2018 at Cleveland. The trial had to be stopped after only 1 month of recruitment in Cleveland because the packaged study medications (memantine) expired and we were unable to procure the dosage required. Among 41 eligible patients, 27 (66%) were randomized. The recruitment rate/week was 0.63, 95% confidence interval (CI): 0.47– 0.79 in Hamilton; and 1, 95% CI: 0.83– 1.17 in Cleveland. Follow-up was complete for all 24 patients (100%) in Hamilton, and 3 of 4 patients in Cleveland. In total, only 4 patients (15%), and 2 patients (7%) had persistent pain at rest and with movement, respectively. There were no significant differences between groups for other outcomes.Conclusion: The trial had to be stopped prematurely due to non-availability of study medications. Trial feasibility objectives of recruiting 90% of eligible patients and recruiting at least one patient/week per site were not met. Consideration for protocol changes will be necessary for the full trial.Trial Registration: NCT02950233.Keywords: persisting pain, chronic pain, prevention, NMDA antagonists, steroids, ketamine

The Thermoregulatory Threshold in Humans during Halothane Anesthesia. By Sessler DI, Olofsson CI, Rubinstein EH, Beebe JJ: ANESTHESIOLOGY 1988; 68: 836-42. Reprinted with permission.Although suppression of thermoregulatory mechanisms by anesthetics is generally assumed, the extent to which thermoregulation is active during general anesthesia is not known. The only thermoregulatory responses available to anesthetized, hypothermic patients are vasoconstriction and nonshivering thermogenesis. To test anesthetic effects on thermoregulation, the authors measured skin-surface temperature gradients (forearm temperature - fingertip temperature) as an index of cutaneous vasoconstriction in unpremedicated patients anesthetized with 1% halothane and paralyzed with vecuronium during elective, donor nephrectomy. Patients were randomly assigned to undergo maximal warming (warm room, humidified respiratory gases, and warm intravenous fluids; n = 5) or standard temperature management (no special warming measures; n = 5). Skin-surface temperature gradients of 4°C or more were prospectively defined as significant vasoconstriction. Normothermic patients (average minimum esophageal temperature = 36.4° ± 0.3°C [SD]) did not demonstrate significant vasoconstriction. However, each hypothermic patient displayed significant vasoconstriction at esophageal temperatures ranging from 34.0 to 34.8°C (average temperature = 34.4° ± 0.2°C). These data indicate that active thermoregulation occurs during halothane anesthesia, but that it does not occur until core temperature is approximately 2.5°C lower than normal. In two additional hypothermic patients, increased skin-temperature gradients correlated with decreased perfusion as measured by a laser Doppler technique. Measuring skin-surface temperature gradients is a simple, noninvasive, and quantitative method of determining the thermoregulatory threshold during anesthesia. [ABSTRACT FROM AUTHOR]

BACKGROUND: Low mean arterial pressure (MAP) and deep hypnosis have been associated with complications and mortality. The normal response to high minimum alveolar concentration (MAC) fraction of anesthetics is hypotension and low Bispectral Index (BIS) scores. Low MAP and/or BIS at lower MAC fractions may represent anesthetic sensitivity. The authors sought to characterize the effect of the triple low state (low MAP and low BIS during a low MAC fraction) on duration of hospitalization and 30-day all-cause mortality. METHODS: Mean intraoperative MAP, BIS, and MAC were determined for 24,120 noncardiac surgery patients at the Cleveland Clinic, Cleveland, Ohio. The hazard ratios associated with combinations of MAP, BIS, and MAC values greater or less than a reference value were determined. The authors also evaluated the association between cumulative triple low minutes, and excess length-of-stay and 30-day mortality. RESULTS: Means (±SD) defining the reference, low, and high states were 87 ± 5 mmHg (MAP), 46 ± 4 (BIS), and 0.56 ± 0.11 (MAC). Triple lows were associated with prolonged length of stay (hazard ratio 1.5, 95% CI 1.3-1.7). Thirty-day mortality was doubled in double low combinations and quadrupled in the triple low group. Triple low duration >=60 min quadrupled 30-day mortality compared with <=15 min. Excess length of stay increased progressively from <=15 min to >=60 min of triple low. CONCLUSIONS: The occurrence of low MAP during low MAC fraction was a strong and highly significant predictor for mortality. When these occurrences were combined with low BIS, mortality risk was even greater. The values defining the triple low state were well within the range that many anesthesiologists tolerate routinely. [ABSTRACT FROM AUTHOR]

BACKGROUND: Volume replacement with colloid solution and topical [alpha]-2 agonists may each moderate the progressive increase in intraocular pressure (IOP) during prone surgery. The authors tested the hypotheses that during prolonged prone surgery, IOP increases less with goal-directed intravenous administration of 5% albumin than with goal-directed administration of lactated Ringer's solution, and with topical [alpha]-2 agonist brimonidine than with placebo eye drops. METHODS: Patients having complex prone spine surgery were factorially randomized to albumin and topical placebo (n = 15); albumin and topical brimonidine (n = 16); lactated Ringer's solution and topical placebo (n = 13); and lactated Ringer's solution and topical brimonidine (n = 16). IOP was measured with a pneumotonometer. The primary outcome was time-weighted average intraoperative IOP. RESULTS: Prone positioning increased IOP a mean ± SD of 12 ± 6 mmHg. IOP increased to 38 ± 10 mmHg at the end of anesthesia (approximately 5.5 h). Time- weighted average intraoperative IOP in the brimonidine group was 4 (95% CI: 1, 8) mmHg lower than in the placebo group (P = 0.023), but no different in the crystalloid and albumin groups (mean difference (95% CI) of -2 (-5, 2) mmHg (P = 0.34). There was no interaction between the two randomized factors. CONCLUSIONS: Brimonidine slightly reduced the primary outcome of intraoperative time-weighted average IOP, whereas there was no significant difference between goal-directed albumin or crystalloid administration. Brimonidine thus helps reduce IOP during spine surgery, but maintaining adequate blood pressure might play a more important role. [ABSTRACT FROM AUTHOR]

Background: Previously, we have demonstrated that extending a continuous femoral nerve block (cFNB) from overnight to 4 days after total knee arthroplasty (TKA) provides clear benefits during the infusion, but not subsequent to catheter removal. However, there were major limitations in generalizing the results of that investigation, and we subsequently performed a very similar study using a multicenter format, with many health care providers, in patients on general orthopedic wards, thus greatly improving inference of the results to the general population. Not surprisingly, the perioperative/short-term outcomes differed greatly from the first, more limited study. We now present a prospective follow-up study of the previously published, multicenter, randomized controlled clinical trial to investigate the possibility that an extended ambulatory cFNB decreases long-term pain, stiffness, and functional disability after TKA, which greatly improves inference of the results to the general population.Methods: Subjects undergoing TKA received a cFNB with ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to continue either perineural ropivacaine (n=28) or normal saline (n=26). Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality of life was measured using the Western Ontario and McMaster Universities Osteoarthritis Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months after surgery. This index evaluates pain, stiffness, and physical functional disability. For inclusion in the analysis, we required a minimum of 4 of the 6 time points, including day 7 and at least 2 of months 3, 6, and 12.Results: The 2 treatment groups had similar Western Ontario and McMaster Universities Osteoarthritis scores for the mean area-under-the-curve calculations (point estimate for the difference in mean area under the curve for the 2 groups [overnight infusion group - extended infusion group]=3.8; 95% confidence interval, -3.8 to +11.3; P=0.32) and at all individual time points (P>0.05).Conclusions: This investigation found no evidence that extending an overnight cFNB to 4 days improves (or worsens) subsequent pain, stiffness, or physical function after TKA in patients of multiple centers convalescing on general orthopedic wards. [ABSTRACT FROM AUTHOR]

We compared the efficacy of the Airway Scope and McCoy laryngoscope as intubation tools with the neck stabilised by a rigid cervical collar. After induction of anaesthesia and neck stabilisation, 100 patients were randomly assigned to tracheal intubation with an Airway Scope or McCoy laryngoscope. Overall intubation success rate, time required for intubation, number of intubation attempts required for successful intubation, and airway complications related to intubation were recorded. Overall intubation success rates were 100% with both devices and a similar number of intubation attempts were required. However, the mean (SD) time required for successful intubation was shorter with the Airway Scope (30 (7) s) than with the McCoy laryngoscope (40 (14) s; p < 0.0001). The incidences of intubation complications were similar, but oesophageal intubation (in six cases) occurred only with McCoy laryngoscope. [ABSTRACT FROM AUTHOR]

BACKGROUND: Many commonly used anesthetic agents produce a dose-dependent amplitude reduction and latency prolongation of evoked responses, which may impair diagnosis of intraoperative spinal cord injury. Dexmedetomidine is increasingly used as an adjunct for general anesthesia. Therefore, the authors tested the hypothesis that dexmedetomidine does not have a clinically important effect on somatosensory and transcranial motor evoked responses. METHODS: Thirty-seven patients were enrolled and underwent spinal surgery with instrumentation during desflurane and remifentanil anesthesia with dexmedetomidine as an anesthetic adjunct. Upper- and lower-extremity transcranial motor evoked potentials and somatosensory evoked potentials were recorded during four defined periods: baseline without dexmedetomidine; two periods with dexmedetomidine (0.3 and 0.6 ng/ml), in a randomly determined order; and a final period 1 h after drug discontinuation. The primary outcomes were amplitude and latency of P37/N20, and amplitude, area under the curve, and voltage threshold for transcranial motor evoked potential stimulation. RESULTS: Of the total, data from 30 patients were evaluated. Use of dexmedetomidine, as an anesthetic adjunct, did not have an effect on the latency or amplitude of sensory evoked potentials greater than was prespecified as clinically relevant, and though the authors were unable to claim equivalence on the amplitude of transcranial motor evoked responses due to variability, recordings were made throughout the study in all patients. CONCLUSION: Use of dexmedetomidine as an anesthetic adjunct at target plasma concentrations up to 0.6 ng/ml does not change somatosensory or motor evoked potential responses during complex spine surgery by any clinically significant amount. [ABSTRACT FROM AUTHOR]

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown. [ABSTRACT FROM AUTHOR]

Boosting a patient's oxygen intake and maintaining normal body heat during and after ob/gyn surgery may cut the postop infection rate. [ABSTRACT FROM AUTHOR]