Effect of cough technique and cryogen gas on temperatures achieved during simulated cryotherapy

Abstract

Background: Cryotherapy is often used to treat cervical precancer in developing countries. There are different methods and cryogen gases used for cryotherapy, including the freeze-flush-freeze (cough) technique employed to minimize gas blockage. However, there is limited information to compare their effectiveness. Methods: Using a tissue model, we compared temperature-time curves for four cryotherapy methods: uninterrupted freezing with nitrous oxide (N2O) and carbon dioxide (CO2), and two methods using a standard and extended version of the cough technique with CO2. Results: Uninterrupted freezing with both N2O and CO2 produced tissue temperatures less than -20°C (-40°C and -30°C respectively). CO2 cryotherapy procedures using the two cough techniques produced temperatures greater than -20°C in the model tissue. Conclusion: CO2 cryotherapy using the cough technique may not achieve sufficiently low temperatures to produce the desired therapeutic effect. Other alternatives to the prevention of gas blockage should be developed. © 2007 Seamans et al; licensee BioMed Central Ltd.