Comparison of intravascular and conventional hypothermia after cardiac arrest

Therapeutic hypothermia is currently the best-documented method of improving neurological outcomes in patients after cardiac arrest and successful resuscitation. There is a variety of methods for lowering body temperature. However, there are no data showing that any specific method of cooling improves the results or increases survival. A simple method involving surface cooling and ice-cold intravenous fluids, as well as more technologically advanced methods, are used in clinical practice. One of the more advanced methods is intravascular hypothermia, during which cooling is carried out with the use of a special catheter located in the central vein.

To compare cooling with the use of intravascular hypothermia and cooling using the traditional method.

A prospective study was performed in 41 patients with acute coronary syndromes who did not regain consciousness after out-of-hospital or in-hospital cardiac arrest and restoration of spontaneous circulation. Therapeutic hypothermia (32-34°C) was obtained with the use of an intravascular method (group A, n = 20) or a traditional method (group B, n = 21) for a period of 24 hours. Intravascular cooling involved the use of a catheter inserted in the femoral vein connected to a heat exchanger (Alsius Coolgard, Zoll, Chelmsford, MA, USA). Traditional cooling was carried out using uncontrolled surface cooling, ice-cold intravenous fluids and ice-cold gastric lavage. Nasopharyngeal and urinary bladder temperatures were recorded hourly. The main analysed temperature was the urinary bladder temperature, as the heat exchanger in the intravascular hypothermia group was controlled by the readings taken from this site. Temperature profiles were compared.

Temperature < 34°C was reached in 19 (95.0%) patients in group A and in 11 (52.4%) patients in group B (p = 0.004). Stable temperature profile (temperature in the range 32-34°C during the final 12 h of cooling) was reached in 16 (80%) patients in group A and in three (14.3%) patients in group B (p < 0.001). Periods of inadequate cooling (temperature > 34°C) and temperature overshoots (temperature < 32°C) were significantly more frequent in group B. Temperature profiles were significantly different in both groups in the readings taken from both sites.

The presented technique of intravascular hypothermia provides more precise temperature control in comparison with the traditional method.