Optimal suction pressure on digital drainage systems for the management of postoperative air leaks together with IL-2 therapy: a retrospective cohort study

INTRODUCTION: Postoperative pulmonary air leaks is one of the most significant complications, which prolongs hospitalization and increases mortality. The sclerosant interleukin-2 (IL-2) has been widely used in China to reduce postoperative air leaks. However, the optimal suction pressure on digital drainage systems when combined with IL-2 treatment remains elusive among thoracic surgeons. This study aimed to determine the optimal suction pressure provided by digital drainage system, together with IL-2 therapy, for effectively sealing air leaks, and to identify the key factors influencing the healing of air leakage. METHODS: O) pressure groups. Univariate and multivariate analyses were employed to evaluate the impact of various variables on the time required for air leak sealing. The variables assessed included age, gender, diagnosis, pulmonary complications, resection site, surgery type, operative time, intraoperative blood loss, and suction pressure during IL-2 treatments. RESULTS: The analysis revealed that suction pressure was a statistically significant determinant of air leak duration (P = 0.036). In multivariate analysis, high suction pressure was independently associated with a longer air leak time by approximately 2.84 days (95% CI: -5.16, -0.52, P = 0.017) and 2.21 days (95% CI: -4.08, -0.35, P = 0.021) compared to low and medium pressure, respectively. Subgroup analysis showed no significant interaction between suction pressure and patient/surgical characteristics, indicating the benefit of lower suction was consistent across the cohort. The number of IL-2 treatments was also a strong predictor of air leak duration (P < 0.001), reflecting the need for repeated therapy in persistent leaks. CONCLUSIONS: Patients receiving IL-2 therapy benefited more from mild suction pressures (low or medium) compared to high suction pressure, resulting in shorter air leak durations across a range of patient and surgical characteristics. These findings support the use of low-to-medium suction (1-9 cmH₂O) as part of the standard management protocol when IL-2 pleurodesis is employed.