Ultrasonographic Assessment of Diaphragmatic Inspiratory Amplitude and Its Association with Postoperative Pulmonary Complications in Upper Abdominal Surgery: A Prospective, Longitudinal, Observational Study

Background: Diaphragmatic dysfunction following upper abdominal surgery is less recognized due to a lack of diagnostic modality for bedside evaluation. We used point-of-care ultrasound to evaluate the diaphragmatic inspiratory amplitude (DIA) in upper abdominal surgery for cancer. Our primary hypothesis was DIA would be reduced in the immediate postoperative period in patients with postoperative pulmonary complications (PPCs). Our aim was to identify an optimal cutoff of DIA for the diagnosis of PPCs. Methods: We conducted a prospective, observational study in patients aged 18 to 75 years undergoing elective, upper abdominal ontological surgeries under combined general and epidural anesthesia. Ultrasound evaluation of the diaphragm was done by measuring the DIA in the right and left hemidiaphragms during quiet and deep breathing on the day before surgery and postoperative days (PODs) 1, 2, and 3. Patients were followed up for PPCs until POD 7.The linear mixed-effects model examined the association between DIA and PPCs and other perioperative factors. Receiver-operating characteristics analysis was done to determine the optimal cutoff of DIA in diagnosing PPCs. Results: DIA measured in the 162 patients showed a significant decrease in their absolute values postoperatively from its preoperative baseline rneasurernent. This decrease in DIA was significantly associated with PPC [right hernidiaphragm, beta = -0.17,95% confidence interval (CI) -031 to -0.02, p = 0.001 during quiet breathing; left hemidiaphragm, beta= -0.24,95% CI = -0.44 to -0.04, p= 0.018 and beta = -0.40, 95% CI = -0.71 to -0.09,p= 0.012 during quiet and deep breathing, respectively]. A cutoff value of DIA of left hemidiaphragm at 1.3 cm during quiet breathing and 1.6cm during deep breathing had a sensitivity of 77 and 75% respectively, in theirability to diagnose PPCs [left hemidiaphragm quiet breathing, area underthe curve (AUC): 0.653, 95% CI 0.539-0.768, p = 0.015; left hemidiaphragm deep breathing, AUC: 0.675, 95% CI 0577-0.773, p= 0.007]. Conclusion: Following upper abdominal surgery, the DIA is decreased and associated with PPCs. DIA of left hemidiaphragm less than 1.3 cm during quiet breathing and 1.6 cm during deep breathing has a sensitivity of 77 and 75%, respectively, in diagnosing PPCs following upper abdominal surgery.

Automated summary

Following upper abdominal surgery, diaphragmatic inspiratory amplitude (DIA) decreases and is significantly associated with postoperative pulmonary complications (PPCs). A DIA of less than 1.3 cm during quiet breathing and 1.6 cm during deep breathing in the left hemidiaphragm has a sensitivity of 77% and 75%, respectively, in diagnosing PPCs following upper abdominal surgery.