Browsing by Author "Du Toit, Leon"

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    A descriptive study of the relationship between preoperative body temperature and intraoperative core temperature change in adults under general anaesthesia
    (2022) Steyn, Francois; Du Toit, Leon; Ross, Hofmeyr
    Background: Despite numerous guidelines on perioperative temperature management, perioperative hypothermia remains common. Prewarming to prevent redistribution hypothermia is supported by evidence, but not widely practiced. We investigate the measurement of preoperative mean body temperature as a potential tool for individualising the practise of prewarming. Methods: We hypothesised that patients who experience intraoperative hypothermia have a lower preoperative mean body temperature. A longitudinal study was conducted in adult patients presenting for ophthalmological surgery under general anaesthesia, to describe the relationship between the incidence of hypothermia within the first hour of anaesthesia and preoperative mean body temperature. Results: Sixty-five patients were enrolled. Twelve participants (18%) presented to the operating theatre hypothermic (core temperature <36.0°C). A further twenty-eight (43%) became hypothermic during the procedure. All hypothermia events occurred within sixty minutes after induction of anaesthesia, and half of the events occurred within nineteen minutes. The difference in preoperative mean body temperature between those with- and without intraoperative hypothermia was only -0.2°C (95% CI -0.4, 0.1). This is neither clinically relevant nor statistically noteworthy. In Cox proportional hazards analysis, BMI and ASA status compounded the observed association between preoperative mean body temperature and the incidence of intraoperative hypothermia. A higher BMI and ASA are associated with a lower incidence of hypothermia. Conclusion: We conclude that intraoperative hypothermia is common and occurs early after induction of anaesthesia. We observed no useful difference in preoperative mean body temperature to help distinguish between patients who become hypothermic and those who do not. Without a useful risk prediction tool, a generic approach to prewarming remains appropriate. Preoperative screening for pre-existing hypothermia should be practiced, even in cases considered as low risk.
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    The effect of patient warming on perioperative cardiovascular outcomes in interventional clinical trials: A systematic review and meta-analysis
    (2023) Mkhize, Sisalindele; Du Toit, Leon; Biccard , Bruce
    BACKGROUND: Perioperative cardiovascular events are a common contributor to perioperative morbidity and mortality. Patient warming affects the cardiovascular system in various ways and may protect against cardiovascular events. We aimed to estimate the effect of active patient warming on perioperative cardiovascular outcomes in clinical trials. METHODS: A systematic review with meta-analyses was conducted. Six data bases were searched from inception until 5th July 2021 for studies that prospectively assigned participants to any physical warming strategy and reported on cardiovascular outcomes. Screening, data extraction and risk of bias assessment were conducted in duplicate. 8782 records were identified. After removing duplicates and screening titles and abstracts, fifty-two full-text articles were assessed for eligibility, fourteen studies with 1711 participants were included in the systematic review and meta-analyses. RESULTS: The effect of physical warming was – risk ratio (95% confidence interval from random effects model) - 0.74 (0.11; 4.73) for major adverse cardiovascular events, 1.07 (0.09; 13.03) for myocardial infarction, 0.56 (0.17; 1.85) for myocardial ischaemia, 0.48 (0.19; 1.20) for arrhythmias and 0.77 (0.25; 2.37) for all-cause mortality. Statistical heterogeneity was not concerning in any of the meta-analyses. All of the meta-analyses carried serious risk of bias and represent low quality evidence. CONCLUSION: We found little information on the treatment effect of active patient warming on cardiovascular outcomes. Inconsistent definitions and reporting of cardiovascular events in patient warming trials confound synthesis of the data. We recommend that prospective studies of patient warming routinely report on cardiovascular outcomes. The effect of active patient warming on perioperative cardiovascular outcomes remains an important unanswered question in perioperative medicine.