Associations of personal temperature exposure in the preceding days with vital signs, biochemical, and hydration parameters in cystic fibrosis.

The impact of long-term exposure to natural high ambient temperatures on people with cystic fibrosis (pwCF) is understudied. In a Mediterranean setting, characterized by prolonged high temperatures, we performed a pilot study to assess personal ambient temperature exposure in pwCF and healthy controls and its impact on physiological parameters. Utilizing a prospective case-control design, we recruited pwCF and paired family controls and assessed, via wearable sensors, personal temperature exposure and physical activity during three two-week periods: summer, early autumn and late autumn-early winter. After each period, key vital signs (systolic and diastolic blood pressure, heart rate, body temperature), pulmonary function, biochemical parameters (serum electrolytes, glucose, urea, creatinine, serum osmolality), and hydration status were assessed. Personal temperature exposure, daily steps and time spent indoors were similar between groups, particularly during summer. In controls, but less so in pwCF, exposure to higher temperature in the preceding days was linked to significantly lower systolic blood pressure (- 2.42 vs. - 1.53 mmHg) and serum glucose (- 5.01 vs. - 3.06 mg/dl) per degree Celsius. In pwCF, urine osmolality (936.1 vs. 628.4 mOsm/kg) was consistently higher and less responsive (38.93 vs. 85.42 mOsm/kg) per rising degree Celsius, compared to controls. In summary, despite similar personal exposures, PwCF show less profound responses after experiencing periods of heat compared to controls, in terms of lowering SBP and serum glucose and increasing urine concentration capacity, suggesting potential weaker acclimatization.