Intravenous Acetaminophen and Ketorolac for Pain Management During Extracorporeal Shockwave Lithotripsy

Extracorporeal shockwave lithotripsy (ESWL) is a common outpatient treatment for renal and ureteric stones, but the shockwaves can be painful and often require intra-procedure sedation and analgesia to improve comfort and allow delivery of an adequate number of shockwaves at therapeutic energy settings. Opioid-based regimens are widely used for ESWL because they are familiar, titratable, and effective; however, peri-procedural opioid exposure is increasingly scrutinized in the context of Canada's opioid crisis.

This study is a prospective quasi-randomized controlled trial in adults undergoing ESWL at St. Joseph's Hospital in Saint John, New Brunswick. The trial compares an opioid-sparing, multimodal regimen (intravenous midazolam, acetaminophen, and ketorolac) with a standard opioid-based regimen (intravenous midazolam and fentanyl). The primary objective is to evaluate the effectiveness of the non-opioid multimodal regimen on procedural pain compared with the standard opioid-based regimen. Secondary objectives include comparing shockwave tolerability and the adverse effect profile between regimens.

Participants are randomly allocated to a regimen and remain blinded to which regimen they receive. Sedation/analgesia is administered intravenously according to the assigned pathway, with midazolam titrated to achieve moderate sedation and analgesia provided via fentanyl (opioid arm) or a multimodal combination of ketorolac and acetaminophen (non-opioid arm).

Pain is measured using a 0-10 numeric rating scale (NRS). The NRS is administered before ESWL and 30 minutes after ESWL. Procedure tolerability is assessed using proxy measures recorded during ESWL (total shockwaves delivered and highest energy level achieved). Adverse medication effects recorded include hypotension, oxygen desaturations, and nausea/vomiting.

The overarching goal is to determine whether an opioid-sparing ESWL pathway can provide equal or superior pain control while maintaining comparable procedural tolerability and safety, supporting routine adoption of non-opioid multimodal analgesia when feasible.

Inclusion criteria

• Age ≥ 19 years
• Undergoing ESWL
• Able to provide informed consent

Exclusion criteria

• Prior ESWL treatment in the past six months
• Narcotic use in the last 48 hours
• Allergy to midazolam, fentanyl, acetaminophen, or ketorolac
• Chronic kidney disease
• Solitary kidney
• Active peptic ulcer disease
• Concurrent anticoagulant prescription
• Liver disease
• Elevated liver function tests
• Pregnancy