To evaluate the physiological effects of continuous Nalbuphine infusion on respiratory drive in post-cardiothoracic surgery patients received mechanical ventilation.

This was a prospective study which enrolled 26 post-cardiothoracic surgery patients received mechanical ventilation admitted to intensive care unit (ICU), Zhongda Hospital from March to December 2019. There were 17 men, aged 59 (49, 69), with acute physiology and chronic health (APACHE Ⅱ) score of (9.5±4.5) and sequential organ failure assessment (SOFA) score of (3.1±2.5). All included patients received mechanical ventilation with PSV mode and continuous Nalbuphine infusion at two dosages. Vital signs and blood gas analysis were recorded before intervention (T0); 1 hour after infusion of nalbuphine with CPOT score of zero (T1); 1 hour after the dose of Nalbuphine was increased by 50% (T2); and 1 hour after the dose of Nalbuphine was adjusted as at T1 (T3). Respiratory drive was evaluated by diaphragm electrical activity (EAdi) and P0.1; the effects of Nalbuphine was evaluated by CPOT and RASS score.

Compared with T0, the CPOT and RASS scores were significantly decreased at 0.10 mg / (kg·h) and 0.15 mg / (kg·h), and patients all achieved satisfactory analgesia / sedation. EAdi at T0 was 6.0 (4.5, 8.0) μV, 6.4 (3.6, 7.4) μV at T1, 5.3 (3.6, 6.0) μV at T2, and 6.1 (4.6, 7.2) μV at T3, showing no significant differences in EAdi at T1, T2 or T3 compared with T0 (P＞0.05). P0.1 at T0 was 2.0 (1.1, 2.9) cmH₂O, 2.0 (0.9, 3.2) cmH₂O at T1, 2.0 (1.1, 3.4) cmH₂O at T2, and 2.2 (1.2, 3.6) cmH₂O at T₃, showing no significant difference in P0.1 at T1, T2 or T3 compared with T0 (P＞0.05). Meanwhile, there were no significant differences in HR, blood pressure, blood gas index, diaphragm activity, diaphragm thickening fraction (DTF), neuro-ventilator efficiency (NVE), neuro-muscular efficiency (NME) between groups (P＞0.05).

Nalbuphine has a satisfactory analgesic effect on post-cardiothoracic surgery patients received mechanical ventilation without obvious effects on respiratory drive, vital sign and diaphragmatic function with increasing the dose.