Effect of the "cough technique" on cryotherapy freezing temperature

To assess the impact of the cough technique on the tip temperature reached in a cryotherapy device commonly used to treat precancerous cervical lesions.

During February to March 2009, bench testing was conducted in Peru on 3 Wallach LL100 cryotherapy units using locally obtained carbon dioxide as the refrigerant. The temperature at the cryo tip was measured continuously with a thermocouple. Mean temperatures recorded with and without the cough technique were compared across the 3 cryotherapy devices.

Higher mean temperatures were observed with the cough technique (-21.7 degrees C [95% CI, -23.0 to -20.4]; -22.0 degrees C [95% CI, -24.2 to -19.7]; -29.4 degrees C [95% CI, -30.3 to -28.6]) compared with mean temperatures observed with the standard procedure (-38.6 degrees C [95% CI, -44.8 to -32.4]; -36.0 degrees C [95% CI, -43.5 to -28.5]; -41.4 degrees C [95% CI, -49.8 to -33.0]). No test performed with the cough technique reached a temperature below -33 degrees C.

Higher temperatures were observed when the cough technique was used. Caution should be exercised by practitioners who use this procedure when performing cryotherapy because the temperatures obtained may not be sufficient to destroy precancerous tissue.