The Ebbinghaus retention curve: training does not increase the ability to apply pressure immobilisation in simulated snake bite—implications for snake bite first aid in the developing world

Summary 

Pressure immobilisation (PIM) has been recommended for field management of bites by some venomous snakes. A narrow range of pressures under the encompassing wrap is necessary for PIM to limit venom spread. This study sought to evaluate the effect of focused training on volunteers’ ability to apply PIM and to retain such skill over time. Forty volunteers were randomly divided into two groups: Group 1 (N=20; controls) received standard written instructions in PIM application; and Group 2 (N=20) received focused instruction during a 4-h training session (including hands-on practice and real-time feedback regarding pressures achieved). After voicing confidence with the technique, volunteers were tested at 1h, 1 day, 3 days and 3 months post training. One-hour post training, no volunteers in the control group were successful in applying PIM with the correct pressure. Twelve volunteers (60%) in Group 2 achieved target pressures 1h after training. However, there was rapid loss of ability to apply PIM correctly by Group 2, falling to just 25% success at 3 days, with little further deterioration at 3 months. Neither written instructions nor intense training with feedback adequately prepares individuals to apply PIM with correct pressures under the wrap.

Keywords: Snakes, Snake bite, Pressure immobilisation method, First aid, Ebbinghaus curve, Cone of Learning