Remembering the Classics: Safety When Flushing Radial Arterial Lines
Justin L Lockman, MD, MSEd, Aditee P Ambardekar, MD, MSEd, Alan Jay Schwartz, MD, MSEd
Original Article
Lowenstein E, Little JW, Lo HH. Prevention of cerebral embolization from flushing radial-artery cannulas. N Engl J Med 1971; 285(25): 1414-5. DOI: 10.1056/nejm197112162852506.
The recent PAAD, “Central arterial catheter placement in children: When it may be worth the risk” (April 28, 2025), reminds us that placement of intraarterial monitoring lines is risky business! That PAAD reviewed Zaleski et al’s1 2024 study of morbidity associated with femoral and axillary artery monitoring in children undergoing cardiac surgery. The take home message from the study reiterated risk:
“…axillary arterial access is associated with a lower rate of complications in pediatric patients undergoing cardiac surgery as compared to femoral arterial access. Serious complications are rare and were limited to femoral arterial lines”1
In that PAAD, Myron expressed his own fear that the close proximity of the axillary artery to the aortic arch might produce embolic strokes when the catheters were flushed, similar to what occurred with temporal artery line placement.2-4 Cerebral embolic disease may not be something you think about with arterial lines (especially peripheral arterial lines). We think this is a good opportunity to review a classic investigation of risk associated with intraarterial monitoring lines published by Lowenstein and colleagues5 in 1971. Their study queried the possibility of causing cerebrovascular injury due to retrograde flow through the axillary artery and into the carotid when flushing radial artery catheters.5 Lowenstein and colleagues completed an exquisitely simple study design (that by today’s research standards might not have been published). Ten adult patients were studied. To identify retrograde flow from the radial artery to the central/cerebral circulation, the flush solution was tagged with sodium pertechnetate whose presence was recognized by placing a gamma ray detector over the area of the subclavian-vertebral artery junction. The average volume of flush that elicited a positive response in adults was 6.6 ml +/- 3.2 ml. There was a positive correlation between volume of flush to elicit a positive response and patient height. By inference, the investigators cautioned that pediatric patients with their shorter stature might be at greater risk of retrograde cerebral flow and embolus than adults.
In 2003, Weiss and colleagues evaluated the risk of cerebral retrograde embolization in neonates and infants whose radial artery catheters were flushed with an infusion bag-pump system delivering fast flow boluses of 0.5-2.0 ml.6 An ultrasonic probe was placed in the jugular fossa to detect micro-air bubbles from retrograde embolization of flush solution into the subclavian and common carotid artery. Sixteen patients up to 105 days old were studied. Retrograde embolization into the subclavian artery was detected in all 16 neonatal/infant patients at syringe pump bolus volumes of 0.5–1.5 mL at 100–200 mmHg infusion bag-pump pressure. In 9 of the 16 patients bubbles were detected in the common carotid artery with 1.5–2.0 mL bolus volumes at 200–300 mmHg infusion bag-pump pressure. The authors stressed:
“In neonates and infants, the standard practice of arterial fast bolus flushing using syringe pump and bag pump flush systems causes retrograde embolization of flush solution into the central arterial and even into the cerebral circulation. The mandatory limitation of fast flush bolus volumes and manometer pressures is urgent in order to reduce retrograde embolization of flush solution and the associated risks in these small patients.”6
In the late 1970s, Prian and colleagues published their selection of the temporal artery for intraarterial monitoring as an alternative to radial and umbilical artery monitoring (both of which were known to have consequential morbidity).3,4 They noted the relative ease cannulating the temporal vessel. Within a brief time (1978), they published several cases of cerebral embolization secondary to temporal artery catheterization.3 Once again, the authors added concern and caution for unanticipated cerebrovascular complications secondary to intraarterial monitoring in pediatric patients. Thus, temporal artery cannulation fell out of favor and we are left with either central or peripheral cannulation below the neck – see the recent PAAD for details about risks and benefits of these sites.
All of these data leave us wondering: if there is so much evidence that retrograde flow can/does happen and that it can easily get to the brain, why hasn’t practice changed after decades? There are certainly safer ways to flush an arterial line with lower volumes and lower pressures. And relatedly, with the many thousands of radial arterial lines placed in children annually, where are all of the patients with cerebrovascular injury? Is injury happening and we are not seeing/looking for it? Is the amount of flow so insignificant that it is clinically irrelevant? Or does it actually explain some of the unexplained brain injury in neonates? We have more questions than answers, and would love to know your thoughts. Send them to Myron at Myasterster@gmail.com and he’ll post in a Friday Reader Response.
References
1. Zaleski KL, Kuntz MT, Staffa SJ, Van Pelt H, Hamilton ARL, Atkinson DB. Central Arterial Line Placement for Pediatric Cardiac Surgery: A Single-Center Experience. Anesthesia and analgesia 2024 (In eng). DOI: 10.1213/ane.0000000000006972.
2. Simmons MA, Levine RL, Lubchenco LO, Guggenheim MA. Warning: serious sequelae of temporal artery catheterization. The Journal of pediatrics 1978;92(2):284. (In eng). DOI: 10.1016/s0022-3476(78)80027-4.
3. Prian GW, Wright GB, Rumack CM, O'Meara OP. Apparent cerebral embolization after temporal artery catheterization. The Journal of pediatrics 1978;93(1):115-8. (In eng). DOI: 10.1016/s0022-3476(78)80619-2.
4. Prian GW. Complications and sequelae of temporal artery catheterization in the high-risk newborn. J Pediatr Surg 1977;12(6):829-35. (In eng). DOI: 10.1016/0022-3468(77)90591-7.
5. Lowenstein E, Little JW, 3rd, Lo HH. Prevention of cerebral embolization from flushing radial-artery cannulas. The New England journal of medicine 1971;285(25):1414-5. (In eng). DOI: 10.1056/nejm197112162852506.
6. Weiss M, Balmer C, Cornelius A, Frey B, Bauersfeld U, Baenziger O. Arterial fast bolus flush systems used routinely in neonates and infants cause retrograde embolization of flush solution into the central arterial and cerebral circulation. Canadian journal of anaesthesia = Journal canadien d'anesthesie 2003;50(4):386-91. DOI: 10.1007/bf03021037.