Evaluation of lung dynamics and respiratory functions in patients undergoing minimal flow anesthesia: a prospective, randomized controlled trial

JOURNAL/mgres/04.03/01612956-202606000-00005/figure1/v/2025-08-18T154854Z/r/image-tiff Low-flow anesthesia aims to minimize anesthetic gas consumption while maintaining adequate anesthesia. To examine the effects of minimal-flow anesthesia on perioperative lung dynamics and postoperative pulmonary function tests, a prospective, randomized controlled study was conducted between October 2023 and March 2024 at Atatürk University. A total of 66 patients (15 males, 45 females) with confirmed American Society of Anesthesiologists (ASA) grade I-II, aged 18-65 years, and scheduled for elective laparoscopic cholecystectomy were included in the study. Patients were randomized into two groups: MeFA (medium flow anesthesia, 2 L/min fresh gas flow) and MiFA (minimal flow anesthesia, 0.5 L/min fresh gas flow). In both groups, dynamic compliance values, peak inspiratory pressure (PIP) values, total inhalation anesthetic drug consumption, total remifentanil drug consumption, duration of anesthesia, duration of surgery, and spirometry test results were recorded. Respiratory measurements were recorded at the 5th minute after intubation (T1), 5th (T2), 10th (T3), 30th (T4), and 60th (T5) minutes after surgical incision and immediately after the surgical suturing (T6) pulse. There was no significant difference in compliance or PIP values between the groups from T1 to T5 (P > 0.05). However, at T6, the MeFA group exhibited a significant decrease in compliance and an increase in PIP compared with the MiFA group (P < 0.05). Additionally, significant differences in compliance and PIP values were found across all time intervals compared with those at T1, except for the T5-6 compliance values in the MiFA group (P < 0.001). No significant difference in respiratory function test values was noted between the groups (P > 0.05). The MiFA group exhibited a relatively milder reduction in compliance values and a lesser elevation in PIP values. Compared with medium-flow anesthesia, minimal-flow anesthesia may help mitigate perioperative lung function deterioration. These findings suggest potential benefits in preserving lung mechanics, warranting further research. This trial was registered at clinicaltrials.gov (identifier No. NCT06055335, registered March 25, 2023).