Direct Optimal Control of Breathable Liquid Temperature for Human Cooling

Ultrafast body cooling of mammals can be achieved by ventilating the lung with a breathable liquid during total liquid ventilation. The instilled liquid into the lung allows to cool the arterial blood temperature, and consequently the organs. While total liquid ventilation can rapidly cool animals, the speed of cooling in humans remains unknown. The problem is to predict the efficiency and safety of the method for humans. The method is based on a previously published mathematical thermal model of mammals in total liquid ventilation. The thermal model is projected to humans. A direct optimal control under constraints is computed to predict the hypothermia induction speed and the sensitivity to parametric uncertainties. The simulated results in human adults illustrate that a worst case optimal control can be used to compute a robust solution in regards to uncertainties of cardiac output and thermal dead volume. In certain patients, brain temperature would reach mild hypothermia in maximum 10 min, with the majority of patients reaching it within 6 min. Hence, the direct optimal control is a potential candidate for the ultrafast therapeutic hypothermia induction for cardio- and neuroprotection of post-cardiac arrest patients.