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Warfarin therapy is underused for stroke prevention in patients with atrial fibrillation. A clearer understanding of warfarin's risk-benefit profile will enable you to prescribe it safely and appropriately. [ABSTRACT FROM AUTHOR]

Purpose: The benefits of intraoperative dialysis during orthotopic liver transplantation remain controversial. In patients with anuric renal failure and portopulmonary hypertension, maintaining venous return during caval clamping and unclamping along with minimizing fluid overload is critical to avoiding right ventricular strain and failure., Clinical Features: We present the case of a 54-yr-old female who underwent orthotopic liver transplantation for alcohol-related liver disease with acute decompensation including severe hepatorenal syndrome (anuric requiring dialysis), probable hepatopulmonary syndrome, moderate pulmonary hypertension (right ventricular systolic pressure, 44 mm Hg), hepatic encephalopathy (grade 2), and esophageal varices. Prior to incision, pulmonary arterial pressures were 48/28 (mean, 35) mm Hg with a central venous pressure of 30 mm Hg, cardiac output of 7.4 L·min -1 , and pulmonary vascular resistance of 98 dynes·sec·cm -5 . In the context of right ventricular strain and volume overload observed on transthoracic echocardiography, we inserted an additional dialysis catheter into the right femoral vein. We initiated dialysis using the two catheters as a circuit (femoral line to the dialysis machine; blood was reinjected via the subclavian line) acting as a limited venovenous bypass, allowing right ventricular offloading and hemodialysis throughout the case. We removed 4.5 L via hemodialysis during the surgery, while avoiding acidosis, hyperkalemia, and sodium shifts. The patient tolerated reperfusion adequately despite pre-existing right ventricular dilation and dysfunction., Conclusion: We report on the use two hemodialysis catheters in a patient undergoing orthotopic liver transplantation as a circuit for simultaneous anuric hepatorenal syndrome and moderate pulmonary hypertension with right ventricular dilation and dysfunction. We believe this technique was instrumental in the patient's successful transplant., (© 2024. Canadian Anesthesiologists' Society.)

Background: Patients with frailty consistently experience higher rates of perioperative morbidity and mortality; however, costs attributable to frailty remain poorly defined. This study sought to identify older patients with and without frailty using a validated, multidimensional frailty index and estimated the attributable costs in the year after major, elective noncardiac surgery., Methods: The authors conducted a retrospective population-based cohort study of all patients 66 yr or older having major, elective noncardiac surgery between April 1, 2012, and March 31, 2018, using linked health data obtained from an independent research institute (ICES) in Ontario, Canada. All data were collected using standard methods from the date of surgery to the end of 1-yr follow-up. The presence or absence of preoperative frailty was determined using a multidimensional frailty index. The primary outcome was total health system costs in the year after surgery using a validated patient-level costing method capturing direct and indirect costs. Secondary outcomes included costs to postoperative days 30 and 90 along with sensitivity analyses and evaluation of effect modifiers., Results: Of 171,576 patients, 23,219 (13.5%) were identified with preoperative frailty. Unadjusted costs were higher among patients with frailty (ratio of means 1.79, 95% CI 1.76 to 1.83). After adjusting for confounders, an absolute cost increase of $11,828 Canadian dollar (ratio of means 1.53; 95% CI, 1.51 to 1.56) was attributable to frailty. This association was attenuated with additional control for comorbidities (ratio of means 1.24, 95% CI, 1.22 to 1.26). Among contributors to total costs, frailty was most strongly associated with increased postacute care costs., Conclusions: For patients with preoperative frailty having elective surgery, the authors estimate that attributable costs are increased 1.5-fold in the year after major, elective noncardiac surgery. These data inform resource allocation for patients with frailty., (Copyright © 2023 American Society of Anesthesiologists. All Rights Reserved.)

Despite being an essential part of whole-person care, patients with cancer often experience complex and under-treated pain. Managing cancer-related pain in patients who are also pregnant compounds the challenge for adequate pain management, as studies have largely excluded this population. Therapy for pain management should be guided by the cause and mechanism of pain. The objective of this review is to provide clinicians with an understanding of pain experienced by pregnant patients with cancer and medications that may be used to help manage cancer-related pain. Nociceptive pain results from damage to somatic or visceral tissues that may be directly caused by cancer. This type of pain can be managed in pregnant patients using acetaminophen and/or nonsteroidal antiinflammatory drugs as first-line agents. In nociceptive pain not managed by non-opioid analgesics, buprenorphine is recommended for those requiring chronic opioids to help manage their pain. Neuropathic pain that results from damage to the peripheral or central nervous system may also be directly caused by cancer, particularly chemotherapy. In pregnant patients, duloxetine and gabapentin should be considered first. Venlafaxine, pregabalin, tricyclic antidepressants, and sodium channel blockers should be avoided, if possible. Nociplastic pain is not directly caused by cancer but may be caused by ongoing peripheral nociceptive input or a condition that predates the cancer diagnosis. Duloxetine and gabapentin are reasonable agents to consider for treatment of nociceptive pain in pregnant patients. Cyclobenzaprine may also be helpful for nociplastic pain., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Unwarranted variation in anaesthesia practice is associated with adverse outcomes. Despite high-certainty evidence of benefit, a minority of hip fracture surgery patients receive a peripheral nerve block. Our objective was to estimate variation in peripheral nerve block use at the hospital, anaesthetist, and patient levels, while identifying predictors of peripheral nerve block use in hip fracture patients., Methods: After protocol registration (https://osf.io/48bvp/), we conducted a population-based cross-sectional study using linked administrative data in Ontario, Canada. We included adults >65 yr of age having emergency hip fracture surgery from April 1, 2012 to March 31, 2018. Logistic mixed models were used to estimate the variation in peripheral nerve block use attributable to hospital-, anaesthetist-, and patient-level factors with use of peripheral nerve block, quantified using the variance partition coefficient and median odds ratio. Predictors of peripheral nerve block use were estimated and temporally validated., Results: Of 50 950 patients, 9144 (18.5%) received a peripheral nerve block within 1 day of surgery. Patient-level factors accounted for 14% of variation, whereas 42% and 44% were attributable to the hospital and anaesthetist providing care, respectively. The median odds ratio for receiving a peripheral nerve block was 5.73 at the hospital level and 5.97 at the anaesthetist level. No patient factors had large associations with receipt of a peripheral nerve block (odds ratios significant at the 5% level ranged from 0.86 to 1.35)., Conclusions: Patient factors explain the minimal variation in peripheral nerve block use for hip fracture surgery. Interventions to increase uptake of peripheral nerve blocks for hip fracture patients will likely need to focus on structures and processes at the hospital and anaesthetist levels., (Copyright © 2021 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Background: Stereotactic brain biopsy techniques have been a focus of rapid technological innovation. The recent advent of frameless stereotaxy has invited the question of whether it can provide the same diagnostic yield as frame-based techniques, without increasing risk of harm to patients. The goal of this meta-analysis was to compare each of these techniques in terms of yield and safety., Methods: We independently searched four databases for English studies comparing frameless and frame-based stereotactic brain biopsies. Our primary outcome was biopsy diagnostic yield. Our secondary outcomes included mortality, morbidity (e.g., symptomatic postbiopsy intracranial hemorrhage, asymptomatic postbiopsy intracranial hemorrhage, new postbiopsy neurological deficit, and postbiopsy seizure), and frequency of repeat biopsy. We calculated pooled estimates and relative risks for dichotomous outcomes using Review Manager 5.3, with corresponding 95% confidence intervals., Results: A total of 3256 stereotactic brain biopsies (2050 frame based and 1206 frameless), from 20 studies, were included in our final analysis. The results did not demonstrate any significant difference between the two stereotactic systems in terms of diagnostic yield (risk ratio [RR] 1.00, 95% confidence interval [CI] 0.99-1.02, P = 0.64, I 2 = 0%). The only significant difference was the increased frequency of asymptomatic hemorrhages in the frameless group (RR 1.37, 95% CI 1.06-1.75, P = 0.01, I 2 = 0%). Application of Grading of Recommendations Assessment, Development, and Evaluation to the results yielded very low quality of all outcomes., Conclusion: Based on very low-quality evidence, both frame-based and frameless stereotaxy are safe and effective for biopsy of intracranial tumors. Further study of patient preference and cost comparing analysis is required to identify if either modality should be preferred., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Surgical Neurology International.)

Objectives: In many jurisdictions, ethical concerns require surrogate humane endpoints to replace death in small animal models of acute lung injury. Heterogenous selection and reporting of surrogate endpoints render interpretation and generalizability of findings between studies difficult. We aimed to establish expert-guided consensus among preclinical scientists and laboratory animal veterinarians on selection and reporting of surrogate endpoints, monitoring of these models, and the use of analgesia., Design: A three-round consensus process, using modified Delphi methodology, with researchers who use small animal models of acute lung injury and laboratory animal veterinarians who provide care for these animals. Statements on the selection and reporting of surrogate endpoints, monitoring, and analgesia were generated through a systematic search of MEDLINE and Embase. Participants were asked to suggest any additional potential statements for evaluation., Setting: A web-based survey of participants representing the two stakeholder groups (researchers, laboratory animal veterinarians). Statements were rated on level of evidence and strength of support by participants. A final face-to-face meeting was then held to discuss results., Subjects: None., Interventions: None., Measurements and Main Results: Forty-two statements were evaluated, and 29 were rated as important, with varying strength of evidence. The majority of evidence was based on rodent models of acute lung injury. Endpoints with strong support and evidence included temperature changes and body weight loss. Behavioral signs and respiratory distress also received support but were associated with lower levels of evidence. Participants strongly agreed that analgesia affects outcomes in these models and that none may be necessary following nonsurgical induction of acute lung injury. Finally, participants strongly supported transparent reporting of surrogate endpoints. A prototype composite score was also developed based on participant feedback., Conclusions: We provide a preliminary framework that researchers and animal welfare committees may adapt for their needs. We have identified knowledge gaps that future research should address., Competing Interests: Drs. McGinn, Fergusson, Barron, Liu, and Lalu institutions received funding from Canadian Institutes of Health Research (CIHR). Dr. Kristof received funding from Ottawa Hospital Research Institute (travel costs). Dr. Downey received support for article research from the National Institutes of Health. Dr. Brown received support for article research from CIHR. Dr. dos Santos disclosed that she is funded by CIHR. Dr. Lalu is supported by The Ottawa Hospital Anesthesia Alternate Funds Association and the University of Ottawa Junior Research Chair in Innovative Translational Research. All of work was completed at the Ottawa Hospital Research Institute in Ottawa, ON, Canada. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2020 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.)

More frequent and intense periods of extreme heat (heatwaves) represent the most direct challenge to human health posed by climate change. Older adults are particularly vulnerable, especially those with common age-associated chronic health conditions (e.g., cardiovascular disease, hypertension, obesity, type 2 diabetes, chronic kidney disease). In parallel, the global population is aging and age-associated disease rates are on the rise. Impairments in the physiological responses tasked with maintaining homeostasis during heat exposure have long been thought to contribute to increased risk of health disorders in older adults during heatwaves. As such, a comprehensive overview of the provisional links between age-related physiological dysfunction and elevated risk of heat-related injury in older adults would be of great value to healthcare officials and policy makers concerned with protecting heat-vulnerable sectors of the population from the adverse health impacts of heatwaves. In this narrative review, we therefore summarize our current understanding of the physiological mechanisms by which aging impairs the regulation of body temperature, hemodynamic stability and hydration status. We then examine how these impairments may contribute to acute pathophysiological events common during heatwaves (e.g., heatstroke, major adverse cardiovascular events, acute kidney injury) and discuss how age-associated chronic health conditions may exacerbate those impairments. Finally, we briefly consider the importance of physiological research in the development of climate-health programs aimed at protecting heat-vulnerable individuals., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: Resident logbooks (RLBs) documenting clinical case exposure are widespread in medical education despite evidence of poor accuracy. Electronic health records (e.g., anesthesia information management systems [AIMS]) may provide advantages for auditing longitudinal case exposure. We evaluated the agreement between AIMS and RLBs for tracking case exposure during anesthesiology residency., Methods: We performed a historical cohort study with anesthesiology residents (2011-2018, all of whom used a RLB contemporaneously with AIMS) working in a multisite academic health sciences network. The primary outcome was total case-load logging; secondary outcomes were volumes for seven surgical specialties (general, gynecology, neuro, orthopedic, thoracic, urology, and vascular surgery). Correlation of case numbers tracked by AIMS vs RLB was assessed using Pearson correlation; agreement was determined using Bland-Altman plots and intraclass correlation coefficients (ICC)., Results: Data from 27 anesthesiology residents were collected. Overall, mean (standard deviation) case numbers were generally greater with AIMS vs RLB [649 (103) vs 583 (191); P = 0.049). Total case volumes between systems had moderate correlation (r = 0.50) and agreement (intraclass correlation coefficient [ICC], 0.42; 95% CI, 0.34 to 0.59). Bland-Altman plots showed variable agreement between AIMS and RLB data [mean (SD) bias = 66 (166) cases]. For general, gynecology, neuro, orthopedic, thoracic, urology, and vascular surgery, there was a range of poor to moderate agreement (ICC, 0.23-0.57) between AIMS and RLB., Conclusion: For anesthesiology resident case-logging, the number of cases logged in an AIMS was higher with lower variance compared with RLBs. Anesthesia information management systems vs RLB data showed low-moderate correlation and agreement. Given the additional time and resources required for RLBs, AIMS may be a superior method for tracking cases where available.

There may be the potential to improve stroke recovery with mesenchymal stem cells (MSCs); however, questions about the efficacy and safety of this treatment remain. To address these issues and inform future studies, we performed a preclinical and clinical systematic review of MSC therapy for subacute and chronic ischemic stroke. MEDLINE, Embase, the Cochrane Register of Controlled Trials, and PubMed were searched. For the clinical review, interventional and observational studies of MSC therapy in ischemic stroke patients were included. For the preclinical review, interventional studies of MSC therapy using in vivo animal models of subacute or chronic stroke were included. Measures of safety and efficacy were assessed. Eleven clinical and 76 preclinical studies were included. Preclinically, MSC therapy was associated with significant benefits for multiple measures of motor and neurological function. Clinically, MSC therapy appeared to be safe, with no increase in adverse events reported (with the exception of self-limited fever immediately following injection). However, the efficacy of treatment was less apparent, with significant heterogeneity in both study design and effect size being observed. Additionally, in the only randomized phase II study to date, efficacy of MSC therapy was not observed. Preclinically, MSC therapy demonstrated considerable efficacy. Although MSC therapy demonstrated safety in the clinical setting, efficacy has yet to be determined. Future studies will need to address the discordance in the continuity of evidence as MSC therapy has been translated from "bench-to-bedside".

Machine learning analysis of social media data represents a promising way to capture longitudinal environmental influences contributing to individual risk for suicidal thoughts and behaviors. Our objective was to generate an algorithm termed "Suicide Artificial Intelligence Prediction Heuristic (SAIPH)" capable of predicting future risk to suicidal thought by analyzing publicly available Twitter data. We trained a series of neural networks on Twitter data queried against suicide associated psychological constructs including burden, stress, loneliness, hopelessness, insomnia, depression, and anxiety. Using 512,526 tweets from N  = 283 suicidal ideation (SI) cases and 3,518,494 tweets from 2655 controls, we then trained a random forest model using neural network outputs to predict binary SI status. The model predicted N  = 830 SI events derived from an independent set of 277 suicidal ideators relative to N  = 3159 control events in all non-SI individuals with an AUC of 0.88 (95% CI 0.86-0.90). Using an alternative approach, our model generates temporal prediction of risk such that peak occurrences above an individual specific threshold denote a ~7 fold increased risk for SI within the following 10 days (OR = 6.7 ± 1.1, P  = 9 × 10 -71 ). We validated our model using regionally obtained Twitter data and observed significant associations of algorithm SI scores with county-wide suicide death rates across 16 days in August and in October, 2019, most significantly in younger individuals. Algorithmic approaches like SAIPH have the potential to identify individual future SI risk and could be easily adapted as clinical decision tools aiding suicide screening and risk monitoring using available technologies., Competing Interests: Competing interestsThe authors have entered into a research partnership with TryCycle Data Systems Inc. on November 14, 2019 to evaluate the efficacy of the above algorithm at identifying SI risk in a clinical setting. This evaluation and the relationship are independent from the work as reported in this journal article. In addition, the authors declare that they do not have any other relationship with the company, and that no financial transactions are involved in this partnership., (© The Author(s) 2020.)

We sought to replicate and expand upon previous work demonstrating antenatal TTC9B and HP1BP3 gene DNA methylation is prospectively predictive of postpartum depression (PPD) with ~80% accuracy. In a preterm birth study from Emory, Illumina MethylEPIC microarray derived 1st but not 3rd trimester biomarker models predicted 3rd trimester Edinburgh Postnatal Depression Scale (EPDS) scores ≥ 13 with an AUC=0.8 (95% CI: 0.63-0.8). Bisulfite pyrosequencing derived biomarker methylation was generated using bisulfite pyrosequencing across all trimesters in a pregnancy cohort at UC Irvine and in 3rd trimester from an independent Johns Hopkins pregnancy cohort. A support vector machine model incorporating 3rd trimester EPDS scores, TTC9B, and HP1BP3 methylation status predicted 4 week to 6 week postpartum EPDS ≥ 13 from 3rd trimester blood in the UC Irvine cohort (AUC=0.78, 95% CI: 0.64-0.78) and from the Johns Hopkins cohort (AUC=0.84, 95% CI: 0.72-0.97), both independent of previous psychiatric diagnosis. Technical replicate predictions in a subset of the Johns Hopkins cohort exhibited strong cross experiment correlation. This study confirms the PPD prediction model has the potential to be developed into a clinical tool enabling the identification of pregnant women at future risk of PPD who may benefit from clinical intervention., Competing Interests: Conflict of Interest Z.K. and J.P. are listed as investors on a patent to use the above biomarkers to predict postpartum depression. Z.K. is the founder of and holds equity in METHYX LLC. He also serves as the company's Managing Member. METHYX LLC intends to license technology used in the study that is described in this publication. This arrangement has been reviewed and approved by the Johns Hopkins University in accordance with its conflict of interest policies. J.P. received legal consulting fees from Astra Zeneca, Eli Lilly, Johnson & Johnson, and Abbott Pharmaceuticals and received research support from the NIMH, the Stanley Medical Research Foundation, and SAGE Therapeutics. No additional conflicts of interest are noted., (Copyright © 2019. Published by Elsevier B.V.)

Background: Physical activity (PA) remains under prescribed by physicians. Motivation and confidence are clear drivers of frequency of promoting PA. Research shows demographic differences in physicians' preventive practices, yet none have included medical students who form habits during training., Objectives: Study objectives were to (i) examine how Canadian medical students' motivation to recommend PA to future patients differs according to six demographic variables (i.e. gender, ethnicity, year of study, university, proposed specialty and academic background) and (ii) examine how Canadian medical students' confidence to recommend PA to future patients differs according to these same demographic variables., Methods: A cross-sectional design was used. First to fourth year medical students from three medical schools responded to an online survey (N = 221)., Results: Female participants were more motivated to counsel patients on PA and refer to an exercise specialist compared to males (P < 0.01). Second year students were more motivated to assess a patients' level of PA compared to third and fourth year students (P < 0.01). Students pursuing family medicine were more confident to assess and counsel compared to students pursuing paediatrics (P < 0.01)., Conclusion: Given that motivation and confidence have a positive influence on frequency-promoting PA, these results suggest where future efforts should focus, to improve PA promotion in medical practice. Physical inactivity continues to be a major issue worldwide, and medical students as future physicians have a unique opportunity to enhance PA amongst the population., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved.For permissions, please e-mail: journals.permissions@oup.com.)

Despite the evidence supporting the benefits of physical activity in the prevention and treatment of most medical conditions, physical activity remains under-prescribed by physicians. Medical students will form habits during training that they are likely to maintain as future physicians. The overall purpose of this study was to investigate the underlying mechanism(s) contributing to frequency in recommending physical activity, to provide insight into how we can increase physical activity recommendations in future practice as physicians. First to fourth year medical students at three Canadian universities responded to an online survey ( N  = 221; 12% response rate) between November 2017 and January 2018. Results revealed that engaging in strenuous physical activity was a strong predictor for frequency in recommending physical activity to patients ( p  < .001). Confidence in recommending physical activity mediated the relationship between strenuous physical activity and frequency recommending physical activity ( p  = .005); motivation did not mediate this relationship. Students were more motivated, than they were confident, to assess, advise, counsel, prescribe and refer patients regarding physical activity ( p  < .05). While 70% of students stated they are aware of the Canadian physical activity guidelines, only 52% accurately recalled them. Findings suggest that increased training related to physical activity should be included in the medical school curriculum to increase students' confidence to recommend physical activity. Another way to increase confidence and frequency in recommending physical activity is to help students engage in more strenuous physical activity themselves, which will ultimately benefit both medical students and their future patients., Competing Interests: None to declare.

Poor reporting quality may contribute to irreproducibility of results and failed 'bench-to-bedside' translation. Consequently, guidelines have been developed to improve the complete and transparent reporting of in vivo preclinical studies. To examine the impact of such guidelines on core methodological and analytical reporting items in the preclinical anesthesiology literature, we sampled a cohort of studies. Preclinical in vivo studies published in Anesthesiology, Anesthesia & Analgesia, Anaesthesia, and the British Journal of Anaesthesia (2008-2009, 2014-2016) were identified. Data was extracted independently and in duplicate. Reporting completeness was assessed using the National Institutes of Health Principles and Guidelines for Reporting Preclinical Research. Risk ratios were used for comparative analyses. Of 7615 screened articles, 604 met our inclusion criteria and included experiments reporting on 52 490 animals. The most common topic of investigation was pain and analgesia (30%), rodents were most frequently used (77%), and studies were most commonly conducted in the United States (36%). Use of preclinical reporting guidelines was listed in 10% of applicable articles. A minority of studies fully reported on replicates (0.3%), randomization (10%), blinding (12%), sample-size estimation (3%), and inclusion/exclusion criteria (5%). Statistics were well reported (81%). Comparative analysis demonstrated few differences in reporting rigor between journals, including those that endorsed reporting guidelines. Principal items of study design were infrequently reported, with few differences between journals. Methods to improve implementation and adherence to community-based reporting guidelines may be necessary to increase transparent and consistent reporting in the preclinical anesthesiology literature., Competing Interests: The authors have declared that no competing interests exist.

Population aging and global warming generate important public health risks, as older adults have increased susceptibility to heat stress (SHS). We defined and validated sex-specific screening criteria for SHS during work and leisure activities in hot environments in individuals aged 31-70 years using age, anthropometry, and cardiorespiratory fitness. A total of 123 males and 44 females [44 ± 14 years; 22.9 ± 7.4% body fat; 40.3 ± 8.6 peak oxygen uptake (mlO 2 /kg/min)] participated, separated into the Analysis (n = 111) and Validation (n = 56) groups. Within these groups, participants were categorized into YOUNG (19-30 years; n = 47) and OLDER (31-70 years; n = 120). All participants performed exercise in the heat inside a direct calorimeter. Screening criteria for OLDER participants were defined from the Analysis group and were cross-validated in the Validation group. Results showed that 30% of OLDER individuals in the Analysis group were screened as SHS positive. A total of 274 statistically valid (p < 0.05) criteria were identified suggesting that OLDER participants were at risk for SHS when demonstrating two or more of the following (males/females): age ≥ 53.0/55.8 years; body mass index ≥29.5/25.7 kg/m 2 ; body fat percentage ≥ 28.8/34.9; body surface area ≤2.0/1.7 m 2 ; peak oxygen uptake ≤48.3/41.4 mlO 2 /kg fat free mass/min. In the Validation group, McNemar χ 2 comparisons confirmed acceptable validity for the developed criteria. We conclude that the developed criteria can effectively screen individuals 31-70 years who are at risk for SHS during work and leisure activities in hot environments and can provide simple and effective means to mitigate the public health risks caused by heat exposure.

We evaluated the extent to which age, cardiorespiratory fitness, and body fat can independently determine whole-body heat loss (WBHL) in 87 otherwise healthy adults. We show that increasing age is a major predictor for decreasing WBHL in otherwise healthy adults (aged 20-70 years), accounting for 40% of the variation in the largest study to date. While greater body fat also had a minor detrimental impact on WBHL, there was no significant role for cardiorespiratory fitness.

Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body's ability to dissipate heat during exercise. These include the activation of the body's sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as phenotypic factors such as age, sex, acclimation, fitness, and chronic diseases (e.g., diabetes). The influence of these factors extends into recovery such that marked impairments in thermoregulatory function occur, leading to prolonged and sustained elevations in body core temperature. Irrespective of the level of hyperthermia, there is a time-dependent suppression of the body's physiological ability to dissipate heat. This delay in the restoration of postexercise thermoregulation has been associated with disturbances in cardiovascular function which manifest most commonly as postexercise hypotension. This review examines the current knowledge regarding the restoration of thermoregulation postexercise. In addition, the factors that are thought to accelerate or delay the return of body core temperature to resting levels are highlighted with a particular emphasis on strategies to manage heat stress in athletic and/or occupational settings., (Copyright © 2017 the American Physiological Society.)

The proportion of older workers has increased substantially in recent years, with over 25% of the Canadian labour force aged ≥55 years. Along with chronological age comes age-related declines in functional capacity associated with impairments to the cardiorespiratory and muscular systems. As a result, older workers are reported to exhibit reductions in work output and in the ability to perform and/or sustain the required effort when performing work tasks. However, research has presented some conflicting views on the consequences of aging in the workforce, as physically demanding occupations can be associated with improved or maintained physical function. Furthermore, the current methods for evaluating physical function in older workers often lack specificity and relevance to the actual work tasks, leading to an underestimation of physical capacity in the older worker. Nevertheless, industry often lacks the appropriate information and/or tools to accommodate the aging workforce, particularly in the context of physical employment standards. Ultimately, if appropriate workplace strategies and work performance standards are adopted to optimize the strengths and protect against the vulnerability of the aging workers, they can perform as effectively as their younger counterparts. Our aim in this review is to evaluate the impact of different individual (including physiological decline, chronic disease, lifestyle, and physical activity) and occupational (including shift work, sleep deprivation, and cold/heat exposure) factors on the physical decline of older workers, and therefore the risk of work-related injuries or illness.

We examined the separate and combined effects of plasma osmolality and baroreceptor loading status on postexercise heat loss responses. Nine young males completed a 45-min treadmill exercise protocol at 58 ± 2% V̇o2 peak, followed by a 60-min recovery. On separate days, participants received 0.9% NaCl (ISO), 3.0% NaCl (HYP), or no infusion (natural recovery) throughout exercise. In two additional sessions (no infusion), lower-body negative (LBNP) or positive (LBPP) pressure was applied throughout the final 45 min of recovery. Local sweat rate (LSR; ventilated capsule: chest, forearm, upper back, forehead) and skin blood flow (SkBF; laser-Doppler flowmetry: forearm, upper back) were continuously measured. During HYP, upper back LSR was attenuated from end-exercise to 10 min of recovery by ∼0.35 ± 0.10 mg·min(-1)·cm(-2) and during the last 20 min of recovery by ∼0.13 ± 0.03 mg·min(-1)·cm(-2), while chest LSR was lower by 0.18 ± 0.06 mg·min(-1)·cm(-2) at 50 min of recovery compared with natural recovery (all P < 0.05). Forearm and forehead LSRs were not affected by plasma hyperosmolality during HYP (all P > 0.28), which suggests regional differences in the osmotic modulation of postexercise LSR. Furthermore, LBPP application attenuated LSR by ∼0.07-0.28 mg·min(-1)·cm(-2) during the last 30 min of recovery at all sites except the forehead compared with natural recovery (all P < 0.05). Relative to natural recovery, forearm and upper back SkBF were elevated during LBPP, ISO, and HYP by ∼6-10% by the end of recovery (all P < 0.05). We conclude that 1) hyperosmolality attenuates postexercise sweating heterogeneously among skin regions, and 2) baroreceptor loading modulates postexercise SkBF independently of changes in plasma osmolality without regional differences., (Copyright © 2016 the American Physiological Society.)

Many studies have aimed to identify the controllers of sweating using ventilated capsules with intradermal microdialysis. It is unclear, however, if the surface area covered by the capsule influences the observed response as a result of differences in the number of sweat glands affected by the infused pharmacological agent relative to the total glands captured by the capsule. We evaluated the area of skin perfused with agents delivered via microdialysis. Thereafter, we developed a specialized sweat capsule (1.1 cm(2)) and compared the sweating response with a classic capsule (2.8 cm(2)). InProtocol 1(n = 6), methacholine was delivered to forearm skin in a dose-dependent manner (1-2000 mmol L(-1)). The area of activated sweat glands was assessed via the modified iodine-paper technique. InProtocol 2(n = 6), the area of inhibited sweat glands induced by ouabain and atropine was assessed during moderate-intensity cycling. Marked variability in the affected skin area was observed (0.9 ± 0.4 to 5.2 ± 1.1 cm(2)). InProtocol 3(n = 6), we compared the attenuation in local sweat rate (LSR) induced by atropine between the new and classic capsule during moderate-intensity cycling. Atropine attenuated sweating as assessed using the new (control: 0.87 ± 0.23 mg min(-1) cm(-2)vs. atropine: 0.54 ± 0.22 mg min(-1) cm(-2);P < 0.01) and classic (control: 0.85 ± 0.33 mg min(-1) cm(-2)vs. atropine: 0.60 ± 0.26 mg min(-1) cm(-2);P = 0.05) capsule designs. Importantly, responses did not differ between capsule designs (P = 0.23). These findings provide critical information regarding the skin surface area perfused by microdialysis and suggest that use of a larger capsule does not alter the mechanistic insight into the sweating response gained when using microdialysis., (© 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

The effects of type 1 and type 2 diabetes on the body's physiological response to thermal stress is a relatively new topic in research. Diabetes tends to place individuals at greater risk for heat-related illness during heat waves and physical activity due to an impaired capacity to dissipate heat. Specifically, individuals with diabetes have been reported to have lower skin blood flow and sweating responses during heat exposure and this can have important consequences on cardiovascular regulation and glycemic control. Those who are particularly vulnerable include individuals with poor glycemic control and who are affected by diabetes-related complications. On the other hand, good glycemic control and maintenance of aerobic fitness can often delay the diabetes-related complications and possibly the impairments in heat loss. Despite this, it is alarming to note the lack of information regarding diabetes and heat stress given the vulnerability of this population. In contrast, few studies have examined the effects of cold exposure on individuals with diabetes with the exception of its therapeutic potential, particularly for type 2 diabetes. This review summarizes the current state of knowledge regarding the impact of diabetes on heat and cold exposure with respect to the core temperature regulation, cardiovascular adjustments and glycemic control while also considering the beneficial effects of maintaining aerobic fitness.

We examined whether sustained changes in baroreceptor loading status during prolonged postexercise recovery can alter the metaboreceptors' influence on heat loss. Thirteen young males performed a 1-min isometric handgrip exercise (IHG) at 60% maximal voluntary contraction followed by 2 min of forearm ischemia (to activate metaboreceptors) before and 15, 30, 45, and 60 min after a 15-min intense treadmill running exercise (>90% maximal heart rate) in the heat (35°C). This was repeated on three separate days with continuous lower body positive (LBPP, +40 mmHg), negative (LBNP, -20 mmHg), or no pressure (Control) from 13- to 65-min postexercise. Sweat rate (ventilated capsule; forearm, chest, upper back) and cutaneous vascular conductance (CVC; forearm, upper back) were measured. Relative to pre-IHG levels, sweating at all sites increased during IHG and remained elevated during ischemia at baseline and similarly at 30, 45, and 60 min postexercise (site average sweat rate increase during ischemia: Control, 0.13 ± 0.02; LBPP, 0.12 ± 0.02; LBNP, 0.15 ± 0.02 mg·min(-1)·cm(-2); all P < 0.01), but not at 15 min (all P > 0.10). LBPP and LBNP did not modulate the pattern of sweating to IHG and ischemia (all P > 0.05). At 15-min postexercise, forearm CVC was reduced from pre-IHG levels during both IHG and ischemia under LBNP only (ischemia: 3.9 ± 0.8% CVCmax; P < 0.02). Therefore, we show metaboreceptors increase postexercise sweating in the middle to late stages of recovery (30-60 min), independent of baroreceptor loading status and similarly between skin sites. In contrast, metaboreflex modulation of forearm but not upper back CVC occurs only in the early stages of recovery (15 min) and is dependent upon baroreceptor unloading., (Copyright © 2015 the American Physiological Society.)

This study evaluated the separate and combined roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in forearm sweating and cutaneous vasodilatation in older adults during intermittent exercise in the heat. Twelve healthy older (62 ± 7 years) males performed two 30 min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C, 20% relative humidity). The exercise bouts were followed by 20 and 40 min of recovery, respectively. Forearm sweat rate (ventilated capsule) and cutaneous vascular conductance (CVC, laser Doppler perfusion units/mean arterial pressure) were evaluated at four skin sites that were continuously perfused via intradermal microdialysis with: (1) lactated Ringer solution (Control), (2) 10 mm ketorolac (non-selective COX inhibitor), (3) 10 mm N(G) -nitro-l-arginine methyl ester (l-NAME; non-selective NOS inhibitor) or (4) a combination of 10 mm ketorolac + 10 mm l-NAME. Sweating was not different between the four sites during either exercise bout (main effect P = 0.92) (average of last 5 min of second exercise, Control, 0.80 ± 0.06; ketorolac, 0.77 ± 0.09; l-NAME, 0.74 ± 0.07; ketorolac + l-NAME, 0.77 ± 0.09 mg min(-1) cm(-2) ). During both exercise bouts, relative to CVC evaluated at the Control site (average of last 5 min of second exercise, 69 ± 6%max), CVC was similar at the ketorolac site (P = 0.62; 66 ± 4%max) whereas it was attenuated to a similar extent at both the l-NAME (49 ± 8%max) and ketorolac + l-NAME (54 ± 8%max) sites (both P < 0.05). Thus, we demonstrate that NOS and COX are not functionally involved in forearm sweating whereas only NOS contributes to forearm cutaneous vasodilatation in older adults during intermittent exercise in the heat., (© 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.)