Association of Daily Variance in Air Temperature With Postoperative Adhesive Small Bowel Obstruction

The influence of air temperature on adhesive small bowel obstruction (ASBO) is unknown. This study aimed to investigate the relationship between air temperature and postoperative ASBO. Overall, 312 patients with postoperative ASBO were included. They were categorized into two groups: the surgery group (n = 83) comprising patients who needed surgery, and the non-surgery group (n = 229) comprising patients who responded to conservative treatment. The associations between patients' characteristics and weather variables on days of symptom onset with the need for surgical management were investigated. Weather variables included the daily mean barometric pressure, daily mean air temperature, day-to-day differences, daily variances, and diurnal variation in the air temperature. Day-to-day differences in weather variables were calculated as the daily mean variables on the day of symptom onset minus those on the previous day. The daily variances in weather variables were defined as the absolute value of day-to-day differences. Compared to the non-surgery group, the surgery group had older patients (75 vs. 70 years, p = 0.009), a higher proportion of female patients (44.6% vs. 32.3%, p = 0.046), increased incidence of closed-loop sign (50.6% vs. 0.9%, p < 0.001), a lower proportion of feces sign (18.1% vs. 31.3%, p = 0.024), and a prolonged hospital stay (11 vs. 22 days, p < 0.001). The number distribution of patients in the surgery group in day-to-day differences in air temperature was different from that of the non-surgery group; the former has several peaks whereas the latter has almost one peak. Daily variance in mean air temperature on the day of symptom onset was higher in the surgery group than in the non-surgery group (2.3 vs. 1.3℃, p < 0.001). Multiple logistic regression analysis revealed that increased daily variance in air temperature on the onset day was associated with the need for surgical management (odds ratio 1.254, p = 0.002) and closed-loop obstruction (odds ratio 1.235, p = 0.017). Regarding seasonal variations, the risk of the need for surgery and closed-loop obstruction in each ASBO patient was the highest in spring, followed by that in summer, autumn, and winter. Consistently, the daily variance in mean air temperature in spring was higher than that in summer, autumn, and winter (p < 0.0001, p < 0.0001, and p = 0.0047, respectively). The risk of the need for surgery and closed-loop obstruction in each ASBO patient was the highest in spring, f