title: Heat stress is associated with reduced health status in pulmonary arterial hypertension: a prospective study cohort.
abstract: BACKGROUND
  Summer heat waves with temperature extremes are becoming more frequent with growing numbers in morbidity and mortality in patients with respiratory diseases. The aim of this study was to evaluate the ramifications of heat stress (temperature >25 °C) on the health status of patients with pulmonary arterial hypertension (PAH).
  
  
  METHODS
  Fifteen patients with PAH (mean age = 66.7 ± 5.2 years) continuously wore an accelerometer from April 1 to September 30, 2011, and their daily step count was recorded. In addition, patients kept a diary to record data on seven standardized questions regarding their daily symptoms. Echocardiography, 6-minute walk test, NTproBNP, and Modified Medical Research Council Scale (MMRC) were assessed at baseline and at the end of the study after 6 months.
  
  
  RESULTS
  On heat-stress days, patients showed significantly more symptoms and lower total steps/day compared to thermal comfort days (3,995 ± 2,013 steps/day vs. 5,567 ± 2,434 steps/day, respectively; P < 0.001). There was a significant negative correlation between total steps/day and Temp(max) (R = -0.47; P < 0.001) and humidity (R = -0.34; P < 0.001). A significant positive correlation was found between daily symptoms and Temp(max) (R = +0.79; P < 0.001) and humidity (R = +0.23; P < 0.001).
  
  
  CONCLUSIONS
  Heat stress is associated with a compromised clinical status in patients with PAH. Adaptation strategies must be implemented to prevent heart-related morbidity, including therapeutic adjustments and adequate room cooling in the patient's home and at the hospital.
authors.affiliation: Division of Pneumological Oncology and Transplantology, Charité Universitätsmedizin Berlin, Campus Charité Mitte, Charitéplatz 1, 10117, Berlin, Germany, melissa.jehn@charite.de.
authors.forename: Melissa
authors.initials: M
authors.lastname: Jehn
authors.forename: Andreas
authors.initials: A
authors.lastname: Gebhardt
authors.forename: Uta
authors.initials: U
authors.lastname: Liebers
authors.forename: Bahar
authors.initials: B
authors.lastname: Kiran
authors.forename: Dieter
authors.initials: D
authors.lastname: Scherer
authors.forename: Wilfried
authors.initials: W
authors.lastname: Endlicher
authors.forename: Christian
authors.initials: C
authors.lastname: Witt
mesh_terms: D056044:Actigraphy; D000203:Activities of Daily Living; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005858:Germany; D006304:Health Status; D018882:Heat Stress Disorders / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D006976:Hypertension, Pulmonary / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010446:Peptide Fragments / Q000097:blood; D011446:Prospective Studies; D012621:Seasons; D013997:Time Factors; D014504:Urban Health
chemical_list: D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain