Effects of hydromorphone-based patient-controlled intravenous analgesia on postoperative hypoxaemia: a randomised controlled non-inferiority clinical trial.

OBJECTIVE: This study aimed to compare the effects of patient-controlled intravenous analgesia (PCIA) with and without low-basal infusion on postoperative hypoxaemia. DESIGN: A randomised parallel-group non-inferiority trial. SETTING: The trial was conducted at a grade-A tertiary hospital from December 2021 to August 2022. PARTICIPANTS: 160 adults undergoing gastrointestinal tumour surgery and receiving postoperative PCIA. INTERVENTIONS: Participants randomly received a low-basal (0.1 mg/hour of hydromorphone) or no-basal infusion PCIA for postoperative 48 hours. PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcome was area under curve (AUC) per hour for hypoxaemia, defined as pulse oxygen saturation (SpO2) <95%. Secondary outcomes included: AUC per hour at SpO2<90% and <85%, hydromorphone consumption, ambulation time and analgesic outcomes up to 48 hours after surgery. RESULTS: Among 160 randomised patients, 159 completed the trial. An intention-to-treat analysis showed that AUC per hour (SpO2<95%) was greater in the low-basal infusion group compared with the no-basal infusion group, with a median difference of 0.097 (95% CI 0.001 to 0.245). Non-inferiority (margin: ratio of means (ROM) of 1.25) was not confirmed since the ROM between the two groups was 2.146 (95% CI 2.138 to 2.155). Hydromorphone consumption was higher in the low-basal group than in the no-basal group (median: 5.2 mg versus 1.6 mg, p<0.001). Meanwhile, there were no differences in the AUC values at the other two hypoxaemia thresholds, in ambulation time, or pain scores between the groups. CONCLUSIONS: Among the patients receiving hydromorphone PCIA after gastrointestinal tumour resection, low-basal infusion was inferior to no-basal infusion PCIA for postoperative hypoxaemia at SpO2<95% up to 48 hours after surgery. TRIAL REGISTRATION NUMBER: ChiCTR2100054317.

Effects of hydromorphone-based intravenous patient-controlled analgesia with and without a low basal infusion on postoperative hypoxaemia: study protocol for a randomised controlled clinical trial.

INTRODUCTION: When patients receive patient-controlled intravenous analgesia (PCIA), no basal infusion is always recommended, as the addition of a basal infusion increases the occurrence of postoperative opioid-induced respiratory depression. However, few studies have investigated whether low basal infusions increase the incidence of postoperative hypoxaemia relative to no basal infusion. We intend to conduct a clinical trial to test the hypothesis that PCIA with a low basal infusion does not increase the occurrence of postoperative hypoxaemia relative to PCIA with no basal infusion. METHODS AND ANALYSIS: This single-centre parallel randomised controlled clinical trial will be conducted with 160 patients undergoing gastrointestinal tumour surgery. The assigned nurse will set analgesic pumps (low or no basal infusion PCIA) according to block-based randomisation sequence. Other investigators and all participants will be blinded to intervention allocation. All patients will be monitored continuously with the ep pod, a wireless wearable device, recording of oxygen saturation (SpO2) and daily ambulation duration for 48 hours postoperatively. Three follow-up evaluations will be conducted to assess the analgesic effect (Numeric Rating Scale (NRS) pain score) and opioid-related side effects (Overall Benefit of Analgesic Score (OBAS)). The primary outcome will be the area under the curve for hypoxaemia (defined as SpO2<95%) per hour. The secondary outcomes will be the areas under the curve for hypoxaemia defined as SpO2<90% and <85% per hour, hydromorphone consumption, OBASs at 24 and 48 hours postoperatively, NRS scores at 4, 24 and 48 hours postoperatively, and the ambulation time per hour over 48 hours. ETHICS AND DISSEMINATION: The study has been approved by the Xijing Hospital Ethics Committee (KY20212163-F-1). Written informed consent will be obtained from all patients or their authorised surrogates. All data will be managed with confidentiality. Findings will be disseminated at international conferences and in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ChiCTR2100054317.