In and ex-vivo Myocardial Tissue Temperature Monitoring by Combined Infrared and Ultrasonic Thermometries

International audienceThe success of cardiac surgery essentially depends on tissue preservation during intervention. Consequently a hypothermic cardio-plegia is applied in order to avoid ischemia. However, myocardial temperature is not monitored during operation. The aim of this study is then to find a relevant and simple method for myocardial global temperature estimation in real time using both ultrasounds and infra-red thermography. In order to quantify the sensitivity of ultrasonic velocity to temperature, a 2.25 MHz ultrasonic probe was used for ex-vivo tests. Pig myocards (n=25) were placed in a thermostatically-controlled water bath and measurements of the ultrasound velocity were realized from 10 to 30 ˚C. The results of this study indicate that the specificity and sensitivity of the ultrasonic echo delay induced by the modification of temperature can be exploited for in-depth thermometry. In parallel, for TIR experiments, a bolometer was used to detect the myocardium surface thermal evolution during in-vivo pig heart experiments. Hypothermic cardioplegic solutions were injected and infra-red surface imaging was performed during one hour. In the near futur, the correlation of the ultrasound and the infrared measurements should allow the real time estimation of the global temperature of the heart. The final objective being to realize in vivo measurements on human hearts, this information may have a very high importance in terms of per-operation inspection as well as decision making process during medical interventions

Surveillance de la protection myocardique en chirurgie cardiaque par investigation multi-physique : Étude de faisabilité

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Persistent contamination of heater–cooler units for extracorporeal circulation cured by chlorhexidine–alcohol in water tanks

International audienceRecently, surgical site infections due to non-tuberculous mycobacteria (NTM) have been linked to heater-cooler unit contamination. The European Centre for Disease Prevention and Control and manufacturers now recommend the use of hydrogen peroxide in filtered water to fill heater-cooler unit tanks. After implementation of these measures in our hospital, heater-cooler units became heavily contaminated by opportunistic waterborne pathogens such as Pseudomonas aeruginosa and Stenotrophomonas maltophilia. No NTM were detected but fast-growing resistant bacteria could impair their detection. The efficiency of hydrogen peroxide and chlorhexidine-alcohol was compared in situ. Chlorhexidine-alcohol treatment stopped waterborne pathogen contamination and NTM were not cultured whereas their detection efficiency was probably improved