Effect of Incentive Spirometer on Arterial Blood Gases in Liver Transplant Recipients.

BACKGROUND: Postoperative pulmonary complications (PPCs) remain highly prevalent after liver transplantation (LT), driven by impaired preoperative respiratory reserve and early postoperative physiological instability. Incentive spirometry (IS) is widely used to promote lung expansion; however, evidence of its efficacy in LT recipients remains limited. This study evaluated the effect of adjunctive IS on arterial blood gas (ABG) levels and early postoperative recovery in LT recipients. METHODS: In this prospective, randomized controlled study, 40 adults undergoing living-donor LT were assigned to standard post-transplant mobilization and breathing exercises alone (n = 20) or standard exercises plus structured IS training (n = 20). ABG parameters (arterial pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), bicarbonate concentration (HCO3 -), and peripheral capillary oxygen saturation (SpO2)) were measured at baseline and on postoperative days 1-3. Linear mixed-effects models were used to assess group differences in ABG trajectories, and slope analyses quantified the decline and recovery phases. Secondary outcomes included intensive care unit (ICU) and hospital length of stay and the incidence of PPCs. RESULTS: Both groups had similar baseline characteristics and comparable immediate postoperative declines in ABG values. IS significantly accelerated recovery across all ABG parameters (group × time P < 0.003), with faster improvement in arterial pH, PO2, HCO3 -, and SpO2 and higher PCO2, consistent with the enhanced ventilation. IS use was associated with earlier ICU discharge. The incidence of PPCs remained high in both groups, with no significant differences. CONCLUSION: Adjunctive IS markedly improved early ABG normalization and shortened ICU stay in LT recipients, suggesting enhanced ventilatory efficiency and oxygenation recovery. However, this did not significantly reduce PPCs. Incorporating structured and supervised IS into early postoperative rehabilitation may provide clinically meaningful physiological benefits. Larger randomized controlled trials are required to confirm these findings. CLINICAL TRIAL NUMBER: The Clinicaltrials.gov registration number is NCT07318766, retrospectively registered on January 5, 2026.