Hot climate and perioperative outcome in elderly patients

Background: It is well known that heat wave is a major cause of weather related mortality in extreme of ages. While auditing our hospital mortality record, we found higher surgical mortality in the months of summer season which inspired us to look into the impact of hot climate in elderly surgical patients.
Materials and Methods: An observational prospective cohort study was undertaken to study the impact of hot climate on elderly (age > 60 yrs) surgical patients over one year when outside temperature was more than 20 ^o C. 98 elderly patients requiring general anaesthesia for surgery were enrolled. Patients were grouped on the basis of peak outdoor temperature with a cut off value of 30 ^o C. Group I- when peak outdoor temperature ranged between 20-30 ^o C (comfortable zone) and Group II - when peak outdoor temperature ranged above 30 ^o C. To reduce the bias, inclusion and exclusion criterion were defined. Meteorological factors, patient characteristics, surgical risk factors and other related data were noted. Data was analyzed using student′s′t′ and z-test for statistical significance.
Results: There were statistically significant complications and prolonged hospital stay in group II as compared to I (13.21±6.44 Vs 9.81±3.54 days, P value =0.01) on univariate analysis. High risk patients had more complications in hot weather. Stepwise multivariate regression analysis showed higher adverse impact of poor physical and cardiac status than hot climate.
Conclusion: Hot and humid weather adversely affect the perioperative outcome in elderly surgical patients. Patients with poor reserves are at greater perioperative risk during hot and humid climate.