Incidence, risk factors, and outcomes of postoperative hypoxaemic respiratory failure following emergency surgical procedures; A prospective observational study

Abstract

Background: There is little data describing the burden of postoperative hypoxaemic respiratory failure (PHRF) in a low resource - setting such as Uganda. This study set out to determine the incidence, risk factors and outcomes of PHRF following emergency surgical procedures at the casualty theatre at Mulago National Referral Hospital (MNRH). Methods: Patients aged 18 years and above who underwent emergency surgery from March to April of 2022 at the casualty theatre of MNRH were recruited. Data was collected using a structured questionnaire, and the patients were then followed up via mobile phone call after the seventh postoperative day. The data was then entered into Epi-data 3.0 and analysed using Stata 15. A bivariate logistic regression analysis was carried out, and factors with a p value ≤0.2 were considered for multivariate analysis. Results: A total of 389 participants were recruited, and of these, 345 participants had their data analysed. 78.3% (270) were male. The mean age was 39.0 (+/-15.7) years. 14.5% developed PHRF within the first five postoperative days. Within 5 days postoperatively, bivariate analysis revealed that 9 variables were statistically significantly associated with PHRF. ASA score > 2 (RR 6.58; p<0.001), cigarette smoking (RR 4.20; p<0.001), estimated blood loss > 100 mls (RR 2.69; p<0.001), and presence of nasogastric tube preoperatively (RR 5.20; p < 0.001) were all independently associated with PHRF. The mean hospital length of stay was substantially prolonged for those with PHRF within the first five days of surgery; 13 days vs 5 days in those without. The overall mortality on day 28 was 1 death per 1000 days of observation in those without PHRF vs. 40 deaths per 1000 days of observation in patients who developed PHRF. Conclusion: PHRF is common, with a high mortality rate following emergency surgery, and most of the risk factors are modifiable.