Early postoperative arterial hypoxemia can predict postoperative pulmonary complications

Abstract

Background & Objective: Postoperative hypoxemia is very common but not unavoidable. It can lead to pulmonary complications through a variety of routes. This study was designed to evaluate changes in arterial blood gases in the initial days after abdominal surgery and to identify the risk factors for postoperative arterial hypoxemia and the prognostic value of arterial hypoxemia to predict pulmonary complications.

Methodology: 215 consecutive patients undergoing laparotomies under general anesthesia with intubation, age ≥ 18 y, ASA I, II,  were enrolled under convenient sampling. The patients with severe preoperative disease, e.g.,  heart failure grade 3 or 4; liver cirrhosis; kidney failure; or COPD were excluded. One day before the surgery, the spirometric values of the patients were measured. Arterial blood sample (T0) for gas analysis was ontained. Anesthesia technique consisted of midazolam, fentanyl, propofol, esmeron, intubaion and epidural catheter. Patients were monitored in the recovery room for signs of lung complications, VAS pain score, X-ray, blood assessment, and sputum culture if indicated. Arterial blood gas was re-tested after 24 h (T1) and 48 h (T2). The criterion for the diagnosis of arterial hypoxemia was PaO₂/FiO₂ < 300.

Statistical nalysis done in SPSS software (version 16.0). Data presented as mean ± SD or n (%). Student’s t-test, paired t-test and ANOVA test were used as required. Statistical significance was set at P < 0.05.

Results: On the first and second days after surgery, both PaO₂ and PaO₂/FiO₂ decreased significantly compared to the preoperative values. 14 and 30 patients on the first and second day after surgery, respectively had decreased arterial blood oxygen levels. All patients who had hypoxemia on the first day after surgery suffered from hypoxemia on the second day. Decreased arterial blood oxygen level on the second day after surgery is a predictor of postoperative respiratory complications. After the first day of surgery, a Tiffeneau-Pinelli index ≤ 75%, A–aO₂ ≥ 20, and anesthesia duration ≥ 150 min were independent risk factors for arterial hypoxia, whereas after day 2, these were a Tiffeneau-Pinelli index ≤ 75%, A–aO₂ ≥ 20, fluid balance ≥ 1700 ml and preoperative upper respiratory tract infections.

Conclusion: Postoperative arterial hypoxemia on the second day was a prognostic index for postoperative pulmonary complications. Independent risk factors for hypoxemia were identified.

Key words: Postoperative pulmonary complications; Hypoxemia; PaO₂/FiO₂ ratio; Tiffeneau-Pinelli index; A–aO₂

Citation: Pham MQ, Bui HM, Tran TTP, Nguyen TH. Early postoperative arterial hypoxemia can predict postoperative pulmonary complications. Anaesth. pain intensive care 2022;26(2):137-142 ; DOI: 10.35975/apic.v26i2.1819

Received: June 21, 2021, Reviewed: September 27, 2021, Accepted: February 18, 2022