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Posted by Dr Dan Carter
We call it intravenous (IV) therapy for a reason, because we only access veins for infusions. This is done for several reasons: veins are more superficial and easier to access; there are more frequent and serious complications when arteries are cannulated; infusion into arteries requires a pump and competent nursing care; IV infusions are the standard of care for drug and nutrient administration.

Arterial cannulation is a commonly performed procedure in the management of patients who are critically ill. Approximately 8 million arterial catheters are placed yearly in the United States.(1)An indwelling arterial catheter allows for continuous blood pressure (BP) monitoring, frequent blood sampling, and arterial blood gas measurement.

When a physician performs IV infusions on a regular basis for many years they may encounter situations that they have not previously experienced. I had been treating an 84 year old male for cancer with high dose vitamin C for five months; infusions have been done once or twice weekly during this time and venous access had never been a problem. The patient came in for another infusion, which turned out to be an interesting experience for me. After preliminaries such as vital signs were completed, I attempted to insert a catheter (24 gauge by 3/4 inch) into the Dorsal Metacarpal Vein of his right hand; this was unsuccessful. I then attempted the Accessory Cephalic Vein in his right forearm; no go. I asked the patient about his hydration status and he claimed that he had been drinking extra water prior to his appointment as instructed. I then moved to the left antecubital fossa and palpated a vein I have accessed before; there was no palpable pulsation. I inserted the catheter but did not see returns in the flash chamber; the catheter was redirected with similar results. I then advanced the catheter to the hub and noted blood returns, at which point I removed the tourniquet, occluded the catheter tip with digital pressure, removed the stylet, and attached the IV tubing. As soon as digital pressure was removed from the catheter tip, bright red blood entered the IV tubing in a pulsatile  manner.

I thought but did not verbalize “woops.” I obtained several gauze sponges from the chairside table, applied them to the puncture site, and removed the catheter without incident. I told the patient that the site was unsuitable. I then held direct pressure over the site for 10 minutes, during which time I reassured the patient, telling him that I had accessed an artery and that all was well. After 10 minutes I checked the site and did not see any swelling or hematoma. Pressure was re-applied for another 5 minutes after which a pressure bandage was placed. Vital signs were taken and the patient was instructed to call me if he noticed any pain or swelling at the site. He was discharged from the clinic feeling well. I called him at home and told him to examine the site; it was free of swelling or discoloration. I reminded him to call me if anything unusual happened at the site. A phone call the next morning revealed no problems.

Post incident analysis indicated that it was most likely the Ulnar artery that was punctured just distal from its bifurcation with its parent artery, the Brachial. When I was working as a medical technologist I would occasionally be asked to collect arterial blood. The radial artery was the site of choice, and I performed this procedure several times over the years without incident. Just be aware that more superficial arteries are accessible with even a short catheter, and be prepared to treat the arterial puncture appropriately.

Here is an interesting case of inadvertent carotid artery cannulation and the ensuing complications. This patient was dehydrated so venous access was difficult.(2) Paste the reference link into your browser


1. Scheer B, Perel A, Pfeiffer UJ. Clinical review: complications and risk factors of peripheral arterial catheters used for haemodynamic monitoring in anaesthesia and intensive care medicine. Crit Care. Jun 2002;6(3):199-204.

2. Nair S, et al. A case of accidental carotid artery cannulation in a patient for Hemofilter: complication and management. BJMP 2009:2(3)57-58. Accessed 8.8.11.