Incidence and Associated Factors of Postoperative Pulmonary Complications after Abdominal Surgery in the Public Hospital, Addis Ababa, Ethiopia

Postoperative pulmonary complications in patients undergoing upper abdominal surgery: risk factors and predictive models

Postoperative pulmonary complications (PPCs) are unexpected disorders that occur up to 30 days after surgery, affecting the patient's clinical status and requiring therapeutic intervention. Therefore, it becomes important to assess the patient preoperatively, as many of these complications can be minimized with proper perioperative strategies following a thorough preoperative checkup. Herein, we describe the PPCs and risk factors associated with developing PPCs in patients undergoing upper abdominal surgery. Additionally, we compared the accuracy of the American Society of Anaesthesiologists (ASA) score, the Assess Respiratory Risk in Surgical Patients in Catalonia (ARISCAT) score, the 6-Minute Walk Test (6MWT), and spirometry in predicting PPCs. Consenting patients (>18 years) undergoing elective upper abdominal surgery were recruited from November 2021 to April 2023. Clinical history was noted. Spirometry and 6MWT were both performed. Pre-operative ASA and ARISCAT scores were recorded. Postoperative follow-up was conducted to assess respiratory symptoms and the occurrence of PPC. PPC was defined as per EPCO guidelines. A total of 133 patients were recruited, predominantly male. A total of 27 (20.3%) patients developed PPCs. A total of 14 (10.5%) patients had more than one PPC. The most common PPCs developed were pleural effusion (11.3%), respiratory failure (7.5%), and pneumonia (4.5%). We obtained ten statistically significant associated variables on univariable analysis, viz obstructive airway disease (p=0.002), airflow limitation (p=0.043), chest radiography (p<0.001), albumin (p=0.30), blood urea nitrogen (BUN) (p=0.029), aspartate aminotransferase (p=0.019), alanine aminotransferase (p=0.009), forced expiratory volume in one second/forced vital capacity ratio (p=0.006), duration of surgery (p<0.001), and ASA score (p=0.012). On multivariable regression analysis, abnormal chest radiograph [odds ratio: 8.26; (95% confidence interval: 2.58-25.43), p<0.001], BUN [1.05; (1.00-1.09), p=0.033], and duration of surgery [1.44; (1.18-1.76), p<0.001] were found to be independently associated with PPC. The ASA score was found to have better predictive power for the development of PPCs compared to the ARISCAT score but is of poor clinical significance. Additionally, 6MWD and spirometry results were found to lack any meaningful predictive power for PPC. To conclude, preoperative evaluation of the chest radiograph, BUN, and duration of surgery are independently associated with developing PPCs. The ASA score performs better than the ARISCAT score in identifying patients at a higher risk of developing PPCs and implementing preventive measures.

Post-operative pulmonary complications after thoracic and upper abdominal procedures at referral hospitals in Amhara region, Ethiopia: a multi-center study

Background

Thoraco-abdominal surgery cuts through muscle, disrupting the normal structure and function of the respiratory muscles, resulting in lower lung volumes and a higher risk of developing post-operative pulmonary complications (PPC). PPC remains an important cause of post-operative morbidity and mortality and impacts the long-term outcomes of patients after hospital discharge. This study was aimed at determining the incidence and factors associated with postoperative pulmonary complications among patients who underwent thoracic and upper abdominal surgery in the Amhara region of Ethiopia.

Methods

A multi-center follow-up study was conducted from April 1, 2022, to June 30, 2022, at comprehensive specialized hospitals in Amhara regional state, northwest Ethiopia. 424 patients were consecutively included in this study, with a response rate of 100%. A chart review and patient interview were used to collect data. A logistic regression analysis was performed to assess the strength of the association of independent variables with postoperative pulmonary complications.The crude odds ratio (COR) and adjusted odds ratio (AOR) with the corresponding 95% confidence interval were computed. Variables with a p-value of <0.05 were considered statistically significant predictors of the outcome variable.

Results

The incidence of postoperative pulmonary complication was 24.5%. Emergency procedures, preoperative SpO₂ < 94%, duration of surgery >2 h, patients with a nasogastric tube, intraoperative blood loss >500 ml and post-operative albumin <3.5 g/dl were factors associated with pulmonary complications. The most common complications were pneumonia (9.9%) followed by respiratory infection (4.2%).

Conclusion

The incidence of postoperative pulmonary complication after thoracic and upper abdominal surgery remains high. Preoperative SpO₂, duration of surgery, patients having a nasogastric tube, intraoperative blood loss and post-operative albumin were factors associated with post-operative pulmonary complications.