Accidental intra-arterial injection
Stem
A 46-year-old woman, 70 kg, is in recovery after laparoscopic cholecystectomy. Her only IV is a 22-gauge cannula in the medial antecubital fossa, placed preoperatively, with no fluid running. The nurse gives promethazine 12.5 mg through it for nausea. The patient immediately screams with burning pain shooting into her fingers; the hand turns pale and mottled, and bright red blood pulses back into the tubing.
Question
What has happened, and what do you do?
Ideal answer
HeadlineIntra-arterial injection of promethazine into a misplaced cannula; I stop the injection, leave the cannula in, and treat it as acute hand ischemia, calling vascular surgery now.
- Stop injecting, keep the cannula, confirm it is arterial, because it is my route for heparinized saline, local anesthetic or vasodilator into the artery.1
- Systemic heparin unless contraindicated, because thrombosis on injured endothelium drives limb loss.2
- Vascular or hand surgery at the bedside, for angiography and intra-arterial thrombolytic or prostaglandin therapy if ischemia persists.2
- Analgesia and serial hand checks, with new IV access in the other arm.3
- Tell her what happened and file a report, because disclosure and system review are part of management.
Watch for: color, capillary refill, temperature and sensation of the hand, and a tense forearm suggesting compartment syndrome.4
Breaking down the answer
- Why it injures — high lipid solubility and osmolality predict worse injury; damage comes from chemical endothelial injury, vasospasm and thrombosis.3 Changes if: a benign drug such as saline, which needs observation only.
- Drugs that cause trouble — propofol, thiopental, benzodiazepines, phenytoin and antibiotics; almost any fluid other than saline or blood can cause spasm.1 Promethazine injection has carried a boxed warning for severe tissue injury, including gangrene, since 2009.5
- What the evidence supports — anticoagulation plus intra-arterial thrombolytics and prostaglandins may improve outcomes; steroids, vasodilators and sympathetic blocks do not appear to change amputation rates.2 I use blocks for pain and comfort, not as cure.
- Grading the hand — a tissue ischemia score built on color, capillary refill, sensation and temperature predicts outcome; scores of 2 or less do better.3
- No consensus regimen — options reported include stellate ganglion block, high-dose steroids, hyperbaric oxygen and topical nitroglycerin;1 graded on organization: stop, anticoagulate, escalate.
- Why it was missed — no running infusion and a blood-control cannula hide arterial placement; a free-flowing drip would have stalled or backed up.3
Follow-up question
Six hours later, despite a heparin infusion, three fingertips are dusky and cold, and the forearm is firm and painful with passive finger extension. The surgeon asks whether a stellate ganglion block would help. What do you say and do?
Follow-up answer
HeadlineTwo problems: persistent digital ischemia and a likely forearm compartment syndrome; the compartment needs measurement and fasciotomy now, and the block is secondary.
I ask the surgeon for compartment pressures and fasciotomy, and for angiography with intra-arterial thrombolytic or prostaglandin therapy, which is where the evidence points.2 A stellate ganglion block may ease pain and spasm, but it does not appear to change amputation rates,2 and I time any block with the hematology plan, since she is fully anticoagulated. I document the hand examination hourly and keep her informed.
Pitfalls that cost points
- Pulling the cannula out at once; you lose the direct route into the injured artery.1
- Labeling burning pain on injection as "normal propofol pain" when the hand blanches or pain extends distally.
- Trusting a cannula because it flushed easily; an antecubital catheter in the brachial artery flushes too, especially with no infusion running.
Rapid-fire
Q: Preferred route for promethazine? A: Deep intramuscular. IV only at 1 mg/mL or less: adults, diluted in 50 mL saline (100 mL for 75 mg) over 20–40 minutes through a large vein, never hand or wrist.6
Q: Signs a cannula is arterial? A: Pulsatile, bright red backflow, blood drawing back easily, and the hand changing color after injection.3
Q: Classic sequelae? A: Paresthesia, severe pain, motor dysfunction, compartment syndrome, gangrene and limb loss.4
Q: How do you prevent injection into an arterial line? A: Clearly labeled red-tagged arterial tubing without injection ports, and checking the line before every injection.
Numbers to know
| Item | Value |
|---|---|
| Promethazine IV concentration limit | ≤ 1 mg/mL6 |
| Promethazine IV dilution and time, adult | 50 mL saline (100 mL for 75 mg) over 20–40 min6 |
| Promethazine adult IV rate | Up to 2.5 mL/min for doses up to 50 mg6 |
| Tissue ischemia score with better outcome | ≤ 23 |
Links
- ponv, Central venous access and its complications, Vascular access: IJ, femoral, radial, cubital fossa, Disclosing a peri-procedural complication or error
- FDA promethazine injection labeling (2023)
Sources
- 1.AQI-AIRS case 2021-09: If in doubt (ASA Monitor, Learning From Others) · ASA / Anesthesia Quality Institute, 2021 · asa2.silverchair.com
- 2.The incidence, significance, and management of accidental intra-arterial injection: a narrative review · Can J Anaesth (abstract), 2019 · europepmc.orgAbstract only: anticoagulation plus intra-arterial thrombolytics and prostaglandins may improve outcomes; steroids, vasodilators and sympathetic blocks do not appear to influence amputation rates.
- 3.Unforeseen impact of the IV fluid shortage on patient safety: a case of inadvertent intra-arterial injection during general anesthesia · Cureus (PMC12002558), 2025 · pmc.ncbi.nlm.nih.gov
- 4.Complications after unintentional intra-arterial injection of drugs: risks, outcomes, and management strategies · Mayo Clin Proc (abstract), 2005 · europepmc.org
- 5.Moving beyond promethazine: advancing precision in antiemetic therapy · SAGE Open Med (PMC13201936), 2026 · pmc.ncbi.nlm.nih.gov
- 6.FDA requires updates to labeling for promethazine hydrochloride injection products · FDA, 2023 · fda.gov
Facts on this page were checked against these sources on Nov 2, 2026. Guidelines change; confirm doses against current institutional protocols.