Performance of cryotherapy devices using nitrous oxide and carbon dioxide.

摘要

OBJECTIVE: To compare temperatures reached by 4 different cryotherapy devices commonly used to treat precancerous cervical lesions in low-resource countries using nitrous oxide (N(2)O) and carbon dioxide (CO(2)) as well as with and without a gas conditioner. METHODS: Bench testing was conducted using 4 different cryotherapy devices and locally obtained N(2)O and medical- and industrial-grade CO(2) refrigerant with and without a gas conditioner. A thermocouple was used to continuously measure the temperature of the cryotherapy tip. Comparison across the cryotherapy devices was based on the mean and lowest temperatures. RESULTS: Without the gas conditioner, all of the devices tested reached mean temperatures colder than -50 degrees C with N(2)O, although 2 devices reached warmer temperatures in a proportion of N(2)O tests. Only 2 of the devices reached mean temperatures colder than -50 degrees C with CO(2). One-way analysis of variance identified the device as the dominant factor for the temperature differences, while the gas was not a determinant of temperature variation. The gas conditioner hindered the performance of 2 of the devices, and only improved the performance of 1 device. CONCLUSION: Both N(2)O and CO(2) reach appropriate freezing temperatures with some cryotherapy devices. Performance of some cryotherapy devices is suboptimal.