Abstract 16047: Quantifying the Cardiovascular Burden of Extreme Heat: A Meta-Analysis of Over 400 Laboratory-Based Heat Exposure Studies
Bibliographic record
Abstract
Background: Heat waves are associated with increased fatalities from cardiovascular events, which has been attributed to increased cardiac strain secondary to the effects of heat on cardiac function. However, our understanding of these adjustments has come primarily from laboratory research employing insulated/encapsulated heating modalities (hot water perfusion suits). We evaluated whether the cardiac responses seen in this work reflect those experienced in studies exposing participants to high ambient temperatures. Methods: We systematically reviewed studies published up to January 2023 examining cardiac outcomes in adults rendered hyperthermic with water perfusion suits or unencapsulated exposure in a climate chamber. Mixed effects meta-analyses were conducted to evaluate whether changes in each outcome with increasing core temperature were modified by heating modality. We also estimated associations (natural spline) between ambient heat index and thermal and cardiac responses in the climate chamber studies. Results: 584 effect estimates of the heat-induced increase in heart rate (primary outcome) from 406 studies were included (~6800 participant exposures). Heart rate was 7 beats/min [95% CI: 3, 13] greater in the perfusion suit vs. climate chamber studies for similar increases in core temperature (P<0.001). Likewise, there were greater elevations in cardiac output (slope difference: 1.2 L/min/°C [0.1, 2.3]), systolic pressure (14 mm Hg/°C [3, 24]), and rate pressure product (2923 mm Hg·beats/min/°C [1027, 4808]) with rises in core temperature in the perfusion suit compared to climate chambers studies (P≤0.036). In the climate chamber studies, core temperature and heart rate increased as much as 1.0°C [0.8, 1.3] and 31 beats/min [16, 37] (P<0.001) in conditions reflective of deadly North American heat waves (heat index: 50-67°C). Conclusions: Our understanding of the effect of heat on cardiovascular responses primarily comes from encapsulated heating modalities, which we show overestimate heat-induced cardiac burden. To support public health research on extreme heat, we provide the first empirical estimates demonstrating considerable thermal and cardiac strain is experienced in conditions reflective of deadly heat waves.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.021 | 0.034 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.009 | 0.040 |
| Bibliometrics | 0.005 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".