In this 164th episode I welcome back Dr. Gillian Isaac to do another ABA keywords episode. We discuss fentanyl and breathing systems (Mapleson and Circle systems).

CME: https://earnc.me/delVJ8

Great info from Aaron Sandock:

The toxicity was reported in rats and research was published in the early-mid 90’s. 

Gonsowski, C., Laster, M., Eger, E., Ferrell, L. and Kerschmann, R. Toxicity of Compound A in Rats: Effect of a 3-Hour Administration

Anesthesiology. 1994;80(3):566-573. 

https://anesthesiology.pubs.asahq.org/article.aspx?articleid=1949689

It is actually the case that follow up studies were done in the US on volunteer patients through University of Arizona and Medical College of Wisconsin in the later 1990’s.Ebert, T., Frink, E. and Kharasch, E. Absence of Biochemical Evidence for Renal and Hepatic Dysfunction after 8 Hours of 1.25 Minimum Alveolar Concentration Sevoflurane Anesthesia in Volunteers. Anesthesiology. 1998;88(3):601-610.

https://anesthesiology.pubs.asahq.org/article.aspx?articleid=1948570

Kharasch, E. and Jubert, C. Compound A Uptake and Metabolism to Mercapturic Acids and 3,3,3-Trifluoro-2-fluoromethoxypropanoic Acid during Low-flow Sevoflurane Anesthesia. 

Anesthesiology. 1999;91(5):1267-1278.

https://www.ncbi.nlm.nih.gov/pubmed/10551576

The key point of the final article concludes that humans are nearly devoid of renal beta lyase, the key enzyme in directing biodegradation of compound A to the toxic renal thiol. Essentially, this research was done in the late 90’s but the original possibility of renal toxicity in humans from just a few years prior has stuck in peoples’ minds (and therefore textbooks). 

More recent studies agree:

Ong Sio L, Dela Cruz R,  and Bautista A. Sevoflurane and renal function: a meta-analysis of randomized trials.

Med Gas Res. 2017 Oct 17;7(3):186-193.

https://www.ncbi.nlm.nih.gov/pubmed/29152212

Gillian’s random recommendation: Born a Crime by Trevor Noah

Circle C Farm: https://www.circlecfarmfl.com