Cyanide Antidote Kits 

I thought I'd try to address the combination of cyanide/antidote issues that arose last week (while I was at NEWSafety99 - good meeting).

1) What is in the kits? Complete kits have three medications: amyl nitrite caps, sodium nitrite injection, and sodium thiosulfite (I think this is the same stuff as "Stop" solution in photo developing) injection. Amyl nitrite is less common due potential for abuse.  The injection solutions are in standard ampules, not autoinjectors.

1a) It's unlikely that HCN would be a military weapon, but there are plenty of terrorists out there, and HCN is easier to obtain/produce than nerve gas.  The actual antidote for nerve gas (all of 'em) is the same as for organophosphate and carbamate pesticide poisoning (makes sense - this is what nerve gases are): Pralidoxime Cl (aka 2-PAM Cl) plus atropine.  Atropine alone will only address some of the sypmtoms and will do nothing to work on the cause, which is acetylcholinesterase depletion.

2) What is the purpose? Cyanide is a chemical asphyxiant ("blood agent" in military chemical weapons lingo); it complexes the Fe3+ in cytochrome oxidase, thus preventing cellular respiration.  The nitrites in the kit oxidize Fe2+ in hemoglobin to Fe3+, thereby binding the CN there.  As someone pointed out, this creates methemoglobinemia (which is pretty neat if it's not you - the blood actually looks brown, aka "chocolate blood").  The Na2S2O3 (last item from the kit) reacts with the CN to form thiocyanate which is harmlessly excreted.

3) How effective are the kits?  In my opinion, marginal.  We don't carry them in our EMS system because by the time an ambulance arrives, someone with CN exposure will already be dead or will live regardless.  Low doses tend to sicken, high doses tend to kill quickly.  If the kit is available on-site (as it should be) and has someone who knows how to administer it, it may work. For a moderate to severe dose (inhaled or ingested), amyl nitrite alone won't cut it.

4) Who should use the kits?  Trained responders!  This is not something you can learn by watching TV or simply "wanting to do the right thing."  Someone commented on the apparent "CYA attitude" of some of the CHOs - I think that is disingenuous and just plain wrong.  The fact is, there ARE real liability concerns, and they have nothing to do with CYA.  Do you want someone cutting a hole in your throat and sticking a fountain pen in (like Radar did on MASH - I still have people asking me about that when I teach CPR and first aid) because they think you're choking?  How about tying a tourniquet because they think you're bleeding to death?  Unfortunately, that stuff happens even when the "victim" isn't dying.  What if you die anyway?  Do you want the good Samaritan - who will not be protected by the law because s/he went beyond the level of previous training - to spend the next few years in court, possibly losing everything?  Giving injections (especially the big ones in the kit) may not be difficult (after all, MDs can do it), but I wouldn't want my life depending on someone who's never done it and has had no training.  If it's a concern, develop a TRAINED emergency response team - which many industries have.  I'd still hesitate to put the kits on ambulances, but they should be available on site for EMS to use (we have protocols - we don't need to call in for permission).

Okay, that's my soapbox piece.

5) How much advice can we get from our local ER?  Mary Ann was right on target - don't count on much.  When I was Austin EMS's Hazmat Captain, we trained the ERs.  There are good medical references out there (including good FREE stuff from ATSDR).  Make sure your ER, emergency response team, and EMS are informed in advance - remember - they expect YOU to be the experts on chemical exposure!  Don't forget your poison control center - they're not just for emergencies!  Call them for information.

I'll be happy to send a list of medical references on chemical exposure to anyone who wants one.  The list is one I've put together and does not constitute formal product endorsements, etc.  Please request off-line and indicate if you'd prefer a fax or e-mail attachment (MS Word 6).

Jeff Rubin, Asst. Dean for EHS
College of Natural Sciences G2500
W.C. Hogg Building
University of Texas at Austin
Austin, TX 78712-1199
(512) 471-6176 (O)
(512) 471-4998 (F)
jrubin@mail.utexas.edu

"The opinions of Dr. Rubin are not meant to offend anyone unless otherwise specified."