Robot-assisted laparoscopic nephrectomy: early outcome measures with the implementation of multimodal analgesia and intrathecal morphine via the acute pain service

The resulting dataset remained de-identified and did not contain sensitive patient-health information as defined by the institutional Human Research Protections Program, and, therefore, was exempt from the informed consent requirement and approved by our institutional review board. Data were collected retrospectively from the data warehouse of our institution. All data for surgical patients that were scheduled for a robot-assisted partial nephrectomy from 2020 to 2021 were extracted.

This was a retrospective cohort study in which the primary objective was to determine whether there was a decrease in median 24-h opioid consumption (intravenous morphine equivalents [MEQ]) among robotic nephrectomy patients whose pain was managed by the surgical team prior to the APS, versus pain managed by APS. Secondary outcomes included opioid consumption during the 24–48 h and 48–72 h period and length of hospital stay. APS screened patients scheduled for RAPN and RARN for candidacy of ITM. Patients who were on anticoagulation, coagulopathic, allergic to morphine, and refused ITM injection were excluded from the study. ITM injection was performed in the preoperative holding area prior to the patient being transported to the OR suite. All APS patients received perioperative multimodal analgesic regimen. Preoperatively, patients received 975 mg PO acetaminophen (APAP). Based on age and preoperative renal function, patients received 200–300 mcg ITM. All patients had their surgeries performed by one of two urologic oncology surgeons. Insufflation pressures of 15 mmHg were used intraoperatively. Postoperatively, patients’ pain was managed primarily by APS. Patients were prescribed scheduled PO APAP and as needed IV opioids for breakthrough pain. Based on preoperative renal function, majority of postoperative patients also received scheduled low-dose ketorolac (15 mg IV) for 24 h. On postoperative day 1, patients were transitioned from prn IV opioids to PO opioids. PO opioid type and dose were tailored to each patient based on IV opioid requirement, whether or not the patient was opioid naïve and their age. Discharge opioid prescription recommendations were also provided to the surgeons. Prior to APS involvement, surgeons inconsistently prescribed scheduled APAP and rarely utilized ketorolac. Postoperatively, patients received a standard prn IV opioid set (0.5–1 mg hydromorphone every 4 h prn) or prn PO opioid order set (oxycodone 5–10 mg PO every 6 h prn with morphine 2 mg IV prn breakthrough pain). Most patients also received a discharge prescription for oxycodone 5 mg PO #20 without consideration of inpatient opioid requirement. Other data collected included patient age, sex, American Society of Anesthesiologists (ASA) classification score, body mass index (BMI), and history of preoperative opioid use (defined as patients prescribed and confirmed use of preoperative opioids).

Due to the cohorts occurring at the different time periods, we performed a segmented regression analysis of an interrupted time series to model trends in the primary outcome during the: (1) pre-APS study period; (2) immediately after APS (multimodal analgesia with ITM) was initiated; and (3) APS study period. To perform a segmented regression, we utilized the following regression equation:where (Y) = the outcome variable (24-h postoperative opioid consumption measured in MEQs); (T) = continuous variable which indicates time passed from the start of the observation period; (D) = a variable indicating observation collected before or after initiation of APS; and (P) = a continuous variable indicating time passed since APS was implemented in this surgical population. Statistically significant estimates for T would indicate a trend change in the outcome during the pre-APS period; for D would indicate an immediate change in the outcome when APS was started; and for P would indicate a trend change in the outcome during the time period from start of APS to end of study period.