In Response to Snakebite Rebound Coagulopathy by Witham et al.

To the Editor:

In the recent report of 2 cases by Witham et al, ¹ we question the identification of the snake for patient 2, who was “believed to have been bitten on the foot by a copperhead snake” before being airlifted to Fort Worth, Texas, from an outlying hospital, likely to the west of Fort Worth. Fort Worth lies at the western edge of the natural range for copperheads (Agkistrodon contortrix) ² but well within the natural range for western diamondback rattlesnakes (Crotalus atrox). ³ Witham et al provide no further evidence that this was a copperhead and not a rattlesnake.

Significant coagulopathy is primarily characteristic of rattlesnake envenomation ^{4 –}6 and seldom occurs with copperhead envenomation. ^{7 –}9 Lavonas et al ⁷ systematically reviewed 19 cohort studies including 1107 patients treated with Fab antivenom (FabAV). None of the 9 patients with late bleeding had identified copperhead bites: 8 cases were after rattlesnake envenomation, and 1 involved an unidentified snake.

Although patient 1 received 15 vials of FabAV, patient 2 reportedly received only 4 vials of FabAV. Antivenom is the preferred treatment for coagulopathy after crotaline snakebite, whereas blood products tend to produce transient improvement in laboratory values. ¹⁰ The subsequent response to FabAV in both patients appears to corroborate that. We question whether either patient would have experienced a recurrence of abnormal coagulation profiles if they had received additional antivenom during their first hospital admissions.