Prophylactic Adrenaline for Anti Snake Venom Induced Anaphylaxis

ResearchBlogging.org

I had just started working in Critical Care when we got informed that a patient was wheeled into the ER in a state of severe hypotensive shock. It was a person who had traveled to his village home for the weekend and in course of his stay there, had got bitten by a snake. The peripheral healthcare facility was not well staffed and after institution of anti snake venom, the patient was transfered to our hospital. En route from the faraway village, however, he developed hypotension, which worsened to such a state that he was in shock by the time he as transfered to the critical care unit.

snake bite

Thankfully, we managed to resuscitate him, but the snake venom, and the hypotension was more than his kidneys could handle and by the time we managed to restore his blood pressure, acute kidney injury had occurred. A rather convoluted and complicated hospital stay resulted and ultimately, the patient succumbed to complications related to his renal dysfunction. Had he not gone into what we thought was an allergic reaction triggered shock following the anti venom infusion, he would definitely had a better outcome.

The point of this story was that this is a common occurrence in South East Asian settings where equine anti venom serum still finds wide spread use. In this study published in the PLoS Medicine, the authors take a look at Adrenaline, Promethazine and hydrocortisone as a prophylaxis for prevention of such reactions. Before talking about the numbers specifically, here are some interesting pointers on the nature of the occurrence of such anaphylactic reactions:

  • Almost 75% of the patients had some form of allergic response.
  • A staggering 91% of the patients had moderate to severe reactions.
  • 89% of the reactions happened within the first hour.
  • Compared with placebo, adrenaline significantly reduced severe reactions to antivenom by 43% (95% CI 25–67) at 1 h and by 38% (95% CI 26–49) up to and including 48 h after antivenom administration
  • Promethazine and Hydrocortisone did not help.
  • Hydrocortisone negated the action of Adrenaline

Whilst this study shows the importance of using Adrenaline prophylactically, the main issue at hand is to improve the qualities of the available anti snake venoms. As the authors correctly conclude:

Pretreatment with low-dose adrenaline was safe and reduced the risk of acute severe reactions to snake antivenom. This may be of particular importance in countries where adverse reactions to antivenom are common, although the need to improve the quality of available antivenom cannot be overemphasized.

Pretreatment with low-dose adrenaline was safe and reduced the risk of acute severe reactions to snake antivenom. This may be of particular importance in countries where adverse reactions to antivenom are common, although the need to improve the quality of available antivenom cannot be overemphasized.

Reference:

ResearchBlogging.org de Silva, H., Pathmeswaran, A., Ranasinha, C., Jayamanne, S., Samarakoon, S., Hittharage, A., Kalupahana, R., Ratnatilaka, G., Uluwatthage, W., Aronson, J., Armitage, J., Lalloo, D., & de Silva, H. (2011). Low-Dose Adrenaline, Promethazine, and Hydrocortisone in the Prevention of Acute Adverse Reactions to Antivenom following Snakebite: A Randomised, Double-Blind, Placebo-Controlled Trial PLoS Medicine, 8 (5) DOI: 10.1371/journal.pmed.1000435

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