A recent study published in Scientific Reports investigated the impact of ultrasound-guided individualized positive end-expiratory pressure (PEEP) on the severity of atelectasis in patients undergoing elective laparoscopic radical resection for colorectal cancer. The single-center randomized controlled trial, conducted between August 2022 and May 2023, suggests that tailoring PEEP levels based on lung ultrasound findings can significantly reduce postoperative atelectasis.
The study enrolled patients aged 60 years or older with a BMI between 18.5 and 27.9 kg/m2, an ASA physical status classification of II-III, and an ARISCAT score of ≥26 points. Patients were randomized to either an individualized PEEP group (PEEP Ind) or a fixed PEEP group (PEEP 5). In the PEEP 5 group, patients received a fixed PEEP of 5 cmH2O. In the PEEP Ind group, PEEP was initiated at 5 cmH2O and then titrated based on lung ultrasound scores (LUSs) after establishing pneumoperitoneum and Trendelenburg position. PEEP was increased incrementally by 2 cmH2O if LUSs were ≥2, with lung ultrasound repeated 1 minute after each change until LUSs were <2, up to a maximum PEEP of 15 cmH2O. Lung ultrasound was performed by an anesthesiologist blinded to the patient's group assignment at several time points: before anesthesia induction (T0), after mechanical ventilation (T1), after pneumoperitoneum and Trendelenburg (T2), 10 minutes after PEEP application (T3), 1 hour after insufflation (T4), 10 minutes after the end of pneumoperitoneum and Trendelenburg (T5), 10 minutes before extubation (T6), 10 minutes after PACU entry (T7), and on postoperative days 1 (D1) and 3 (D3).
The primary outcome was the severity of atelectasis, assessed using lung ultrasound scores on postoperative days 1 and 3. Secondary outcomes included postoperative hypoxemia, pulmonary embolism, hospital stay duration, and postoperative pulmonary complications (PPCs) within 7 days. Exploratory outcomes included mechanical power (MP) and plasma concentrations of pulmonary injury biomarkers (IL-1, IL-6, IL-10, CC16, and FGF21).
Key Findings
The study found that the individualized PEEP group had significantly lower LUSs on both the first and third postoperative days, indicating reduced atelectasis severity. Specifically, PEEP was adjusted incrementally using a stepwise approach, increasing by 2 cmH2O if LUSs was ≥ 2 until lung aeration (LUSs < 2) was achieved, with a maximum PEEP of 15 cmH2O. After releasing pneumoperitoneum, PEEP was gradually decreased in increments of 2 cmH2O until no atelectasis was detected (LUSs < 2).
Clinical Implications
The results suggest that ultrasound-guided PEEP titration can optimize lung aeration during laparoscopic colorectal surgery, potentially reducing the risk of postoperative pulmonary complications. The approach allows for real-time assessment of lung aeration and adjustment of PEEP levels to minimize atelectasis. This individualized strategy may lead to improved patient outcomes and shorter hospital stays.
