So first about the lidocaine allergy.
My first thought was "BS. No such thing as lidocaine allergy, must be the preservative". Well a quick google and literature search comes up with the following papers (see bottom of post).
To summarize. True lidocaine allergies exist but are pretty bloody rare. If allergy exists appears that bupivicaine and ester anesthestics are still safe.
As for the case.
Patient had art line and CVC placed awake followed by an epidural. 2.5% bupivicaine was used for skin infiltration with plenty of time for onset for the CVC and epidural placement. Epidural was incrementally topped up with Bupi 5% with epi until a surgical level was obtained and the C/S proceeded uneventfully.
Her airway really looked like crap. Would those of you really just do a RSI and see what you can see? What are you going to use to blunt the hemodynamic response to intubation in the setting of AS (sure not that severe of a hemodynamic lesion but what if AVA was 0.8?).
My thoughts before looking up the literature were: 1. Invasive monitoring (Art + CVC, no PAC). 2. Awake FOB but then could not figure out how I was going to topicalize. 3. Then thought do RSI direct look with bougie available and glidescope backup using Remi to blunt effects of laryngoscopy and PEDS aware and ready with the narcan already drawn up (I have only run into 1 case where I could not intubate with this method, unanticipated abnormal airway anatomy and could not even see anything with the glidescope, could still ventilate so just put in an LMA and baged for 45 min until I could reverse the 50 of Roc). But now having gone throught the literature I think I would do art+CVC then Bupi epidural followed by smack up the side of the head to the Obstetrician for not involving us earlier.
CanGas
http://www.theberries.ns.ca/archives/anaesthetics.html
Alleged Allergy to Local Anaesthetics Fisher MM, Bowie CJ Anaesth Intensive care 1997 Dec;25(6):611-4
Fisher et al1 conducted a study to determine the incidence of true local anaesthetic allergy in patients with an alleged history of local anaesthetic allergy and whether subsequent exposure to local anaesthetics was safe. Two hundred and eight patients with a history of allergy to local anaesthetics were referred over a twenty-year period to their Anaesthetic Allergy Clinic at the Royal North Shore Hospital, Sydney, Australia. In this open study, intradermal testing was performed in three patients and progressive challenge in 202 patients. Four patients had immediate allergy and four patients delayed allergic reactions. One hundred and ninety-seven patients were not allergic to local anaesthetics. In 39 patients an adverse response to additives in local anaesthetic solutions could not be excluded. In all but one patient local anaesthesia had been given uneventfully subsequently. They contend, "a history of allergy to local anaesthesia is unlikely to be genuine and local anaesthetic allergy is rare. In most instances it can be excluded from the history and the safety of local anaesthetic verified by progressive challenge."
Understanding Allergic reactions to Local Anaesthetics Eggleston ST, Lush LW Ann Pharmacotherapy 1996 Jul-Aug;30(7-8)851-7
After a Medline search of articles published (over the period 1985-1996) on allergy to local anaesthetics, Egglestone et al2 suggested the following recommendations concerning the appropriate use of local anaesthetics and alternative therapies in patients with documented local anaesthetic reactions. "A true immunologic reaction to a local anaesthetic is rare. Patients who are allergic to ester local anaesthetics should be treated with a preservative-free amide local anaesthetic. If the patient is not allergic to ester local anaesthetics, these agents may be used in amide-sensitive patients. In the rare instance that hypersensitivity to both ester and amide local anaesthetic occurs, or if skin testing cannot be performed, then alternative therapies including diphenhydramine, opiods, general analgesia, or hypnosis can be used."
Contact allergy to lidocaine: a report of sixteen cases. Dermatitis. 2007 Dec;18(4):215-20
Lidocaine is used widely as an injectable local anesthetic, occasionally as an intravenous drug for cardiac arrhythmias, and increasingly as a topical anesthetic. Reports of allergic contact dermatitis and delayed hypersensitivity reactions to this "amide" anesthetic are limited. We report 16 cases of lidocaine contact allergy seen over 5 years. Concomitant patch-test reactions occurred with neomycin 20% (10 cases), bacitracin 20% (9 cases), fragrance mix 8% (3 cases), balsam of Peru 25% (2 cases), and dibucaine 2.5% and benzocaine 5% (1 case each). Patch tests with lidocaine dilutions (in petrolatum) gave the following results: 10% (3 of 4 positive reactions), 5% (4 of 6 positive reactions), and 1% (3 of 6 positive reactions). Intradermal testing with lidocaine 1%, mepivacaine 2%, and bupivacaine 0.5% was performed on 8 patients, resulting in positive reactions to lidocaine in 3 patients and to mepivacaine in 1 patient. Bupivacaine yielded negative results in each of the 8 patients. Relevance of delayed reactions to injectable lidocaine was definite in 2 cases; past, probable, and unknown in 1 case each; and possible in 11 cases. Delayed hypersensitivity to lidocaine may present as "suture allergy," treatment failure, typical contact allergy, or other local skin or dental reactions. Allergen substitution is based on further patch and intradermal testing, the results of which may be discordant.
Evaluation of re-challenge in patients with suspected Lidocaine allergy. Dermatology 2004, vol. 208, no2, pp. 109-111
Background: Lidocaine is an anaesthetic agent used worldwide in various clinical specialties. Although lidocaine hypersensitivity is very rare, clinicians frequently encounter patients with such an alleged diagnosis. Using a questionnaire, we evaluated the results of re-challenge with lidocaine, the gold standard for assessing hypersensitivity reactions in patients who claim to be allergic to this drug. Methods:A detailed questionnaire was sent to members of the French Dermatological Society, targeting the management of patients claiming lidocaine intolerance. After analysis and recall of doubtful episodes, 199 re-challenges were made. True lidocaine hypersensitivity was finally demonstrated in only 1 patient. Conclusions: The results of this study demonstrate that patients claiming to be allergic to lidocaine are usually not, their symptoms corresponding in most cases to a vasovagal episode. Re-challenge is safe and may constitute an easy and cheap alternative to skin testing. This should be performed in specialized centres except in case of a vasovagal episode.
