Total liquid ventilation for whole body cooling in cardiac arrest

Total liquid ventilation for whole body cooling in cardiac arrest

It is know a fairly well known fact that hypothermia helps in producing a favourable neurological outcome after resuscitation from cardiac arrest. Several methods have been used to achieve this means like rapid infusion of cold saline started from the ambulance and use of hypothermia blankets in the emergency department. Now a new experimental approach has been tried by Chenoune and associates in article published ahead of print in Circulation {Ultrafast and Whole-Body Cooling With Total Liquid Ventilation Induces Favorable Neurological and Cardiac Outcomes After Cardiac Arrest in Rabbits. Circulation. 2011 Aug 1. [Epub ahead of print]}. They used total liquid ventilation as a method of ultrafast and whole body cooling in an animal model of cardiac arrest.

Liquid ventilation is a new concept of ventilating the lung with an oxygen rich liquid like perfluorocarbon than with air. Perfluorocarbon has a high solubility for respiratory gases and can carry more oxygen and carbon dioxide than blood. Liquid ventilation could be total or partial. Total liquid ventilation requires a membrane oxygenator, a heater and a pump to deliver and remove perfluorocarbon from the lungs. In partial liquid ventilation, the lung is filled with perfluorocarbon only partially upto the functional residual capacity which comes to about forty percent of the total lung capacity. This is more feasible because further ventilation is with a usual ventilator and clinical applications have been reported in acute respiratory distress syndrome (ARDS), meconium aspiration syndrome, congenital diaphragmatic hernia and respiratory distress syndrome (RDS) of neonates. But equipment should be in place to give the proper initial dose of perfluorocarbons as well as to continue instilling a replacement dose of perfluorocarbons to replace that lost by evaporation.

Chenoune and colleagues induced ventricular fibrillation in rabbits for five or ten minutes and then cardiopulmonary resuscitation and return of spontaneous circulation was achieved. Control group underwent normothermic life support while therapeutic hypothermia was induced by total liquid ventilation with temperature controlled perfluorocarbons in the study group They could achieve very rapid and generalized cooling with total liquid ventilation with esophageal and tympanic temperatures in the range of thirty two and thirty three degrees centigrade within ten minutes. After rewarming, those animals which had cooling with total liquid ventilation had an attenuated neurological dysfunction and decreased mortality at one week. There was also a limitation of myocardial necrosis as evidenced by lower troponin I release and myocardial caspase 3 activity. Conventional cooling or normothermic total lung ventilation did not have a similar benefit as the rapid cooling with total liquid ventilation temperature controlled perfluorocarbons.