Comparison of sevoflurane and propofol on the novel oxygenation index and respiratory mechanics in gynecological laparoscopic surgery: a randomized controlled trial

The novel oxygenation index (NOI), which incorporates mean airway pressure (Pmean) as a key respiratory parameter, is increasingly being investigated for its enhanced ability to reflect patients’ pulmonary function compared to the traditional oxygenation index (OI). This study aimed to compare the effects of sevoflurane and propofol on the NOI in patients undergoing gynecological laparoscopic surgery in the Trendelenburg position. A total of 120 female patients aged 18–45 years scheduled for gynecological laparoscopic surgery were randomly assigned to receive sevoflurane (group sevoflurane [GS]) or propofol (group propofol [GP]). The primary outcome was the NOI, calculated as [(FiO₂ × Pmean)/PaO₂] ×100, with lower values indicating a more favorable status. Secondary outcomes included the ratio of physiologic dead-space over tidal volume [Vd/Vt (%)], lung compliance (LC), driving pressure (ΔP), peak airway pressure (PIP), and mean airway pressure (Pmean). In addition, the total consumption of opioids from patient-controlled intravenous analgesia (PCIA), visual analogue scale (VAS) pain scores, and incidence of postoperative nausea and vomiting (PONV) were also recorded and analyzed. The NOI was significantly lower in the GS than in the GP at 5 min (T2), 30 min (T3), and 60 min (T4) after pneumoperitoneum establishment in the Trendelenburg position (T2: 1.98 ± 0.21 vs. 2.11 ± 0.24, P = 0.003; T3: 2.38 ± 0.24 vs. 2.52 ± 0.31, P = 0.008; T4: 2.59 ± 0.24 vs. 2.92 ± 0.32, P < 0.0001). Patients in the GS had significantly higher LC than those in the GP at the same three time points (T2: 34.35 ± 2.26 vs. 31.31 ± 1.35, P < 0.0001; T3: 30.70 ± 1.40 vs. 28.30 ± 1.37, P < 0.0001; T4: 29.49 ± 1.33 vs. 27.81 ± 1.38, P < 0.0001). In contrast, the Vd/Vt (%), ΔP, PIP, and Pmean were significantly higher in the GP than those in the GS. The total consumption of opioids within 48 h postoperatively was significantly lower in the GS than in the GP ( P < 0.0001). Additionally, the VAS pain scores were significantly lower in the GS than that in the GP at the post-anesthesia care unit (PACU) ( P < 0.0001) and at 24 h postoperatively ( P < 0.0001). The incidence of PONV in the GS was significantly higher than in the GP both in the PACU ( P = 0.003) and at 24 h postoperatively ( P = 0.022). The NOI was progressively increased following the establishment of pneumoperitoneum in the Trendelenburg position. However, patients in the GS maintained a superior NOI compared with those in the GP. Trial registration : The study was registered at clinicaltrials.gov (ChiCTR2200065644 date of registration 10/11/2022).