Comparison of cold crystalloid and colloid infusions for induction of therapeutic hypothermia in a porcine model of cardiac arrest

[A new method for establishing a ventricular fibrillation model by TCEI in Tibetan miniature pig]

OBJECTIVE

To explore an economical, convenient, safe and efficient method for establishing a Tibetan miniature pig model of cardiac arrest (CA).

METHODS

Cardiac puncture was performed in 12 Tibetan miniature pigs using two acupuncture needles. One needle was inserted into the fourth intercostal near the right side of the sternum about 3 cm in depth at an angle of 30° to 60° between the chest and the needle, and the depth was adjusted until the handle of the needle vibrated with the heartbeat without premature ventricular contraction on the electrocardiogram; the other was inserted into the subcutaneous tissue of the left armpit about 3 cm in depth without damaging important organs. The handles of the two needles were connected with 9V dry batteries to form a circuit and generate direct current stimulation. Ventricular fibrillation was produced in the pigs to induce CA by stimulation of transcutaneous electrical induction (TCEI) for 3 s, and the success rate of modeling was recorded. After an interval of 4 min without intervention, cardiopulmonary resuscitation (CPR) was performed using the standard Utstein style, and the survival of the pigs after recovery was observed.

RESULTS

The success rate of ventricular fibrillation modeling was 91.67% (11/12) using this method, and CPR achieved a success rate of 45.45% (5/11) in these models. The subsequent survival of the pigs was 100% (5/5) at 24 h and 80% (4/5) at 72 h. After observation for 72 h, the resuscitated Tibetan miniature pigs were dissected, and no significant damage was found in the vital organs in the thoracic or abdominal cavities.

CONCLUSIONS

We successfully established a model of CA using acupuncture needles and dry batteries in Tibetan miniature pigs, and this method is economical, convenient, safe and efficient.

Normal saline versus colloid solutions for induction of hypothermia: the effect of specific heat capacity on cooling

The prevention of ischemic injury to preserve both end-organ function and improve neurological recovery by the implementation of therapeutic hypothermia has been well established in the literature. However, not only the means by which body temperature is cooled but also the rate by which target temperature is attained remains an area of continued interest and research. The induction of therapeutic hypothermia to begin the process of body temperature lowering through the infusion of a cold solution intravenously into the body may be one variable that influences not only rapidity of cooling but also subsequent clinical outcome. In a recent issue of Critical Care, Skulec and colleagues compared the induction of therapeutic hypothermia by cold normal saline versus cold colloid solution containing hydroxyethyl starch in a porcine animal model of cardiac arrest, assessing both the rate of temperature change and target temperature achieved, in addition to changes in intracranial pressure.