Prolonged exposure to heat does not affect clinical and biochemical characteristics in patients with cystic fibrosis

Abstract

Dehydration and electrolyte imbalance are key clinical characteristics of cystic fibrosis (CF), especially when patients are exposed to high temperatures. However, the effect of prolonged heat exposure on clinical and biochemical status of patients with CF is unknown.

In Cyprus, an island with extreme heat during summer, we used wearable sensors to monitor ambient temperature exposure and physical activity in patients with CF and control individuals for 2 weeks during three periods (summer, early fall, late fall). At the end of each period, all participants were clinically assessed measuring anthropometrics, blood pressure, heart rate, spirometry, serum electrolytes (Na⁺, K⁺, Cl^-), and serum osmolality.

We included 18 patients with CF, median age (IQR) 17.5 (8.4-23.3), and 18 controls, 46.7 (33.6-53.8) in the study. For each period heat exposure and physical activity did not differ between patients and controls. Within the three periods, patients had similar clinical parameters (BMI, total body water, blood pressure, heart rate and FEV1). During summer (min-max T: 23-40°C) no difference was seen between patients and controls in serum electrolytes (for Na⁺ p=0.3, for K⁺ p=0.28, for Cl^- p=0.44) and serum osmolality (p=0.44). In a mixed model, different temperature exposure between the three periods did not influence patients’ weight and BMI variability, heart rate, blood pressure, FEV1, serum electrolytes and serum osmolality.

Our data show that prolonged exposure to heat conditions did not impact the clinical and biochemical profile of patients with CF. Larger studies are needed to confirm these findings and investigate factors that could modulate heat stress in CF.