The role of ultrasonographic lung aeration score in the prediction of postoperative pulmonary complications: an observational study

Abstract

Background Postoperative pulmonary complications (PPCs) are important contributors to mortality and morbidity after surgery. The available predicting models are useful in preoperative risk assessment, but there is a need for validated tools for the early postoperative period as well. Lung ultrasound is becoming popular in intensive and perioperative care and there is a growing interest to evaluate its role in the detection of postoperative pulmonary pathologies. Objectives We aimed to identify characteristics with the potential of recognizing patients at risk by comparing the lung ultrasound scores (LUS) of patients with/without PPC in a 24-h postoperative timeframe. Methods Observational study at a university clinic. We recruited ASA 2–3 patients undergoing elective major abdominal surgery under general anaesthesia. LUS was assessed preoperatively, and also 1 and 24\u2009h after surgery. Baseline and operative characteristics were also collected. A one-week follow up identified PPC+ and PPC- patients. Significantly differing LUS values underwent ROC analysis. A multi-variate logistic regression analysis with forward stepwise model building was performed to find independent predictors of PPCs. Results Out of the 77 recruited patients, 67 were included in the study. We evaluated 18 patients in the PPC+ and 49 in the PPC- group. Mean ages were 68.4\u2009±\u200910.2 and 66.4\u2009±\u20099.6\u2009years, respectively ( p \u2009=\u20090.4829). Patients conforming to ASA 3 class were significantly more represented in the PPC+ group (66.7 and 26.5%; p \u2009=\u20090.0026). LUS at baseline and in the postoperative hour were similar in both populations. The median LUS at 0\u2009h was 1.5 (IQR 1–2) and 1 (IQR 0–2; p \u2009=\u20090.4625) in the PPC+ and PPC- groups, respectively. In the first postoperative hour, both groups had a marked increase, resulting in scores of 6.5 (IQR 3–9) and 5 (IQR 3–7; p \u2009=\u20090.1925). However, in the 24th hour, median LUS were significantly higher in the PPC+ group (6; IQR 6–10 vs 3; IQR 2–4; p \u2009<\u20090.0001) and it was an independent risk factor (OR\u2009=\u20092.6448 CI95% 1.5555–4.4971; p \u2009=\u20090.0003). ROC analysis identified the optimal cut-off at 5 points with high sensitivity (0.9444) and good specificity (0.7755). Conclusion Postoperative LUS at 24\u2009h can identify patients at risk of or in an early phase of PPCs.