Cast saw burns: evaluation of simple techniques for reducing the risk of thermal injury.

BACKGROUND

Although a routine practice in all orthopaedic clinics, the use of cast saws is not without risk of thermal and abrasive injury to patients. This study investigates the use of readily available supplies for reducing oscillating saw blade operating temperatures.

METHODS

An oscillating cast saw blade and an adhesive thermocouple fixed to the blade were uniformly heated and subsequently cooled from 70 °C to 45 °C using 6 different methods. Variables tested included the use of water applied with cotton cast padding or gauze dressing, 70% isopropyl alcohol applied with cotton cast padding, gauze dressing, or commercially available alcohol pads, and ultrasound gel applied with gauze dressing. All methods were tested with either the cast saw off or the saw and vacuum running. Statistical analysis included a 2-way analysis of variance to compare conditions with the cast saw off versus on and Tukey-adjusted pairwise comparisons of individual variables within each group.

RESULTS

Cast saw blade cooling in ambient air required 114.2 seconds, whereas oscillating the blade and using the vacuum reduced the time to 14.6 seconds. Applying 70% isopropyl alcohol with a commercially available pad or ultrasound gel on a gauze dressing only required 9.0 and 10.2 seconds, respectively. Cooling with water or 70% isopropyl alcohol applied with either gauze dressing or cotton cast padding ranged from 4.8 to 7.4 seconds.

CONCLUSIONS

At rest, the cast saw blade required almost 2 minutes to return to safe operating temperatures after being heated to 70 °C. Running the saw and vacuum resulted in significantly faster cooling across all measured variables. Of all methods tested, cooling with 70% isopropyl alcohol using gauze or cast padding or cooling with water on gauze resulted in the fastest responses. As a result, this study suggests that the routine use of any of these 3 methods would significantly decrease the risk of patient discomfort and thermal injury during cast cutting.

CLINICAL RELEVANCE: Provide simple method for decreasing risk of thermal injury when removing casts.