A large-scale study by US researchers has found that short-term exposure to extreme heat causes a small but statistically significant drop in blood pressure among adult patients at outpatient clinics. The findings are reported by infohub.kz.
The results were published in the journal JAMA Network Open. According to News-Medical, a team of US researchers examined the link between short-term exposure to extremely high temperatures and changes in blood pressure readings.
The analysis covered 4,221,866 visits to 2,554 community health organizations across 40 US states. It looked at the summer months from 2019 to 2023. The data came from the national electronic network OCHIN, while heat indicators were calculated using the GridEX climate database.
It emerged that on days of extreme heat, patients' systolic pressure fell by an average of 0.7 millimeters of mercury, and diastolic pressure by 0.3 millimeters of mercury. The most noticeable changes were recorded in people aged 65 and older: their systolic pressure dropped by an average of 1.1 mm Hg, and diastolic by 0.8 mm Hg. Among patients diagnosed with hypertension who were taking medication, systolic pressure fell by an average of 1.0 mm Hg.
The researchers explain that the physiological cause of lower blood pressure in the heat is the dilation of blood vessels and the redistribution of blood flow to the skin. Although the fluctuations identified do not pose a serious individual clinical threat, the body's response in real-world conditions differs from laboratory tests.
The authors conclude that changes in blood pressure are not the main factor behind cardiovascular risks in the heat, and point to the need for further study of biomarkers.