Remember the Classics-Why? Cerebral Embolization From Flushing a Radial Artery Catheter
Alan Jay Schwartz, MS, MSEd
Original article
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. Can J Anaesth. 2003 Apr;50(4):386-91. doi: 10.1007/BF03021037. PMID: 12670817
Original article
E Lowenstein, J W Little 3rd, H H Lo. Prevention of cerebral embolization from flushing radial-artery cannulas. N Engl J Med. 1971 Dec 16;285(25):1414-5. PMID: 5121208 DOI: 10.1056/NEJM197112162852506
It is said that in 1854, it was Oscar Wilde who asserted, “Experience is the hardest kind of teacher. It gives you the test first and the lesson afterward”. So many anesthesiologists can attest to the validity of Wilde’s proclamation. We are so often faced with unintended consequences from our patient care practices, for which we must devise solutions to avoid repetition.
Consider a case in point. Cerebral embolization resulting from flushing a radial artery monitoring catheter. A PubMed search of “cerebral embolization from flushing radial artery” cites a relatively recent publication1 about this complication. This, however, is not a new problem. Fortunately, the same PubMed search cites a classic.2
In 1971, revered MGH cardiac anesthesiologist Ed Lowenstein2 and his colleagues published a classic when they considered the test (unintended retrograde cerebral embolization from flushed radial artery catheters) and conducted an elegantly simple study to define the lesson (controlled flushing of radial artery catheters with small volumes). Their study population consisted of 10 post-cardiac surgery patients. To define the fluid volume required to reach the cerebral circulation, they tagged flush saline with a gamma-ray emitting isotope. They positioned a sensor over the subclavian-vertebral artery junction, injected titrated amounts of tagged flush, as fast as possible, and recorded when gamma-rays were detected.
The average volume of flush solution that resulted in positive detection of the gamma-ray tag was 6.6 + 3.2 ml. Not surprisingly, there was a positive correlation between patient height and volume of flush that resulted in retrograde cerebral flow; beware, therefore when caring for smaller, pediatric, patients. Lowenstein and colleagues commented that their investigation, “…demonstrates that the volume of flush solution necessary to cause embolization of particulate matter or air from the radial artery is surprisingly small.” Having quantitated the volume of flush that might result in cerebral morbidity, these investigators developed a safe arterial flushing system that delivered a small controlled flush volume of no more than 2.2 ml at a time. Lowenstein and colleagues stated the obvious, “Meticulous attention must be paid to avoidance of air bubbles, and extremely small volumes of solution injected at slow rates must be used if central embolization is to be avoided.”
Remember the Classics-Why? Several reasons justify remembering.
1. If “Experience is the hardest kind of teacher. It gives you the test first and the lesson afterward” is a true statement, remembering the classic may obviate our reinventing the wheel. Perhaps if Weiss and colleagues1 had access to “Prevention of cerebral embolization from flushing radial-artery cannulas”2 published 22 years earlier, the modern-day incidence of cerebral embolization might have been less.
2. Since many unintended consequences from our patient care practices are evergreen events, remembering the classics will provide a current specific teaching template for solutions already devised to avoid repetition of morbidity. Ask the question, is there a specific radial artery flushing evidence-based protocol that teaches residents, fellows, nurses, nurse practitioners, physician assistants and any others who might care for intravascular catheters? An answer: the classic is a primary source to reveal and reinforce an evidence-based protocol.
3. It’s possible that the trainee and less experienced practitioner hasn’t asked the questions and considered how to answer them. The classic serves as an elegant example of how our colleagues asked questions and investigated answers. The classic serves as a role model for new queries and solutions
PS From Myron: Intra-arterial monitoring of the newborn for frequent arterial blood gas sampling and analysis has always been a challenge. Cannulation of small arteries such as the radial or pedal can be difficult and is often plagued with complications (eg umbilical to aortic thromboembolus). In the late 1970- early 1980s the temporal artery was frequently used because it was thought easier to cannulate than the radial or posterior tibial arteries. In 1980, Bull et al.3 made the startling discovery of neurological devastation and brain infarcts from these catheters. In similar fashion to Lowenstein’s caution regarding retrograde cerebral circulation when flushing the radial artery catheter, when the temporal artery is selected for monitoring, the unanticipated consequence to recognize is, “The proximity of the temporal artery to the internal carotid circulation makes cerebral embolization a definite possibility.3”
When you are flushing an arterial catheter do you use a syringe or the red pull tab on the transducer? Send your responses and Myron will post in the Friday Reader Response.
References
1. 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. Apr 2003;50(4):386-91. doi:10.1007/bf03021037
2. Lowenstein E, Little JW, 3rd, Lo HH. Prevention of cerebral embolization from flushing radial-artery cannulas. The New England journal of medicine. Dec 16 1971;285(25):1414-5. doi:10.1056/nejm197112162852506
3. Bull MJ, Schreiner RL, Garg BP, Hutton NM, Lemons JA, Gresham EL. Neurologic complications following temporal artery catheterization. The Journal of pediatrics. Jun 1980;96(6):1071-3. doi:10.1016/s0022-3476(80)80646-9