Cystic fibrosis patients struggle to adjust to summer heat: Study
Researchers used wearable sensors during hot and cooler seasons
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People with cystic fibrosis (CF) may have altered responses to high temperatures compared with healthy individuals, a study in Cyprus suggests.
Using wearable sensors during hot and cooler seasons, researchers found that while both groups were exposed to similar temperatures, people with CF showed smaller changes in blood pressure, blood sugar, and urine concentration, “indicating possible weaker acclimatization responses,” the team wrote.
The study, “Associations of personal temperature exposure in the preceding days with vital signs, biochemical, and hydration parameters in cystic fibrosis,” was published in Scientific Reports.
Study conducted during the summer in Cyprus
CF is caused by genetic mutations that result in the loss or dysfunction of the CFTR protein, leading to the accumulation of thick, sticky mucus in various organs and abnormally high levels of chloride in sweat. As a result, people with CF may be at higher risk of losing water and salts when they sweat, especially during warm weather.
However, “the impact of long-term exposure to natural high ambient temperatures on people with cystic fibrosis … is understudied,” the researchers wrote.
To learn more, researchers conducted a pilot study involving 36 participants, including 18 people with CF and 18 controls. The study was carried out during the summers of 2020 and 2021 in Cyprus, an island in the East Mediterranean where periods of intense heat are common during summer.
CF patients and controls experienced similar heat exposure
At the start of the study, CF patients were younger (19.8 vs. 44.2 years) and more commonly male than the controls. They also had significantly lower body weight, body mass index (a measure of body fat based on height and weight), and worse lung function.
Although blood pressure was similar between the two groups, people with CF had significantly higher heart rate and urine osmolality (a measure of the concentration of particles such as sodium, potassium, and urea).
Participants wore sensors that continuously tracked their environmental temperature exposure, activity levels, and time spent indoors. This allowed the researchers to estimate the heat each person was exposed to in the days preceding their clinical assessments.
On average, both groups experienced similar heat exposure, with summer and early autumn temperatures around 30°C (86°F) and cooler seasonal periods around 26°C (about 79°F). There were also no significant differences between the groups regarding mean daily activity levels and time spent indoors.
CF patients showed less pronounced adjustments
The researchers then examined how heat exposure influenced a range of health measures, including blood pressure, blood sugar levels, and hydration markers.
In healthy participants, higher temperatures on the day before a clinical visit were associated with a significant drop in systolic blood pressure (the pressure when the heart contracts) and a reduction in blood sugar levels. In people with CF, similar patterns were observed, but the magnitude of the changes was smaller or not significant.
A similar pattern was seen for hydration-related measures. In healthy individuals, urine osmolality increased significantly following hotter days, meaning their urine became more concentrated. This is typically a sign that the body is conserving water more effectively in response to heat.
In people with CF, however, this increase was much weaker and did not reach statistical significance.
Overall, despite similar temperature exposures, people with CF showed less pronounced adjustments, such as lowering blood pressure and blood sugar, and increasing urine concentration. The authors suggested that this could indicate a reduced ability to acclimatize to prolonged heat exposure.
While these findings may help explain why some CF patients experience dehydration or salt imbalance more easily during hot weather, the study was relatively small and exploratory, meaning further research is needed to confirm the results and understand the underlying mechanisms.
“Future studies in the field may use more advanced wearable technology to measure more personal exposure indices and provide a better insight into the combined effects of heat, anthropometrics [body size and shape] and activity during the monitoring period,” the team concluded. “These studies could also focus further on patient-reported outcomes and effects of heat on the quality of life of patients.”
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