Rapid Development of Brain Hypothermia Using Femoral—Carotid Bypass

Abstract

Abstract. Objectives: Advances in the field of cardiopulmonary resuscitation have led to an increasing number of patients initially surviving sudden cardiac arrest. Unfortunately, most of these patients do not recover from the resultant anoxic brain insult. Several animal and human trials have suggested that post-resuscitative brain hypothermia may improve neurologic recovery after cardiopulmonary arrest. Present cooling methods are slow, induce only brain surface cooling, or result in systemic hypothermia. The authors tested the hypothesis that unilateral hypothermic carotid bypass would induce bilateral brain cooling without evoking systemic hypothermia or hemodynamic instability. Methods: Anesthetized, ventilated common swine (n = 6, 24-37 kg) underwent right femoral and carotid artery bypass cannulation. Central and peripheral hemodynamic parameters were recorded every 2 minutes throughout the procedure. Thermodynamic parameters included bilateral frontal lobe, bilateral nasopharyngeal, pulmonary artery, and rectal temperatures. Hypothermic femoral-carotid bypass was accomplished by drawing blood from the right femoral artery, cooling it to 24ЊC, and returning it to the right carotid artery at a flow rate of 5 mL/kg/min for 30 minutes. Results: With initiation of cooling, brain temperatures dropped rapidly from baseline of 37.2ЊC to 30.6ЊC (right frontal lobe) and 33.1ЊC (left frontal lobe) at 30 minutes. Pulmonary artery and rectal temperatures also decreased, but never reached mild hypothermic levels (34ЊC). There was no significant change in any hemodynamic parameters during brain cooling. Conclusions: Femoral-carotid hypothermic bypass rapidly induced a state of selective brain hypothermia without causing systemic hypothermia or hemodynamic instability. Key words: hypothermia; brain; resuscitation; bypass; cerebral ischemia. ACADEMIC EMERGENCY MEDICINE 2001; 8:303-308 I NCREASING numbers of patients experiencing out-of-hospital cardiac arrest are surviving to hospital admission as a result of improvements in resuscitation techniques.1-3 Unfortunately, most of these patients fail to recover to their previous functional status. [4][5][6] Present therapy during the post-resuscitative period remains largely suppor- tive and directed at preventing further anoxic insult and cardiovascular instability.Recent evidence from both laboratory and human trials suggests that post-resuscitative brain hypothermia may improve functional outcome of survivors from out-of-hospital cardiac arrest. [7][8][9][10][11]

Devices for rapid induction of hypothermia

“…Cannulation of the carotid vessels and the infusion of cooled blood into the cerebrum have been studied in a swine model of cardiac arrest [42]. Animals received selective brain hypothermia (328C) for 12 h using femoral/carotid bypass.…”

Therapeutic Hypothermia in Cardiac Arrest Survivors

“…Some of them, like cardiopulmonary bypass, femorocarotic bypass with extracorporeal cooling of blood, peritoneal cooling or total liquid ventilation cooling are too invasive and/or complicated in comparison with the current effective techniques (Reed et al, 2002;Mori et al, 2001;Hong et al, 2002;Xiao et al, 1995). The others are just in the beginning of their development and perhaps represent the future.…”

Intranasal Perfluorochemical Spray for Preferential Brain Cooling in Sheep

“…Cooling blood with intravenous catheters has gained interest because of its potential for long-term use [16,17]. Extracorporeal cooling strategies have been devised as simple veno-venous cooling or coolant infusion systems, or as sophisticated as carotid heat exchangers for independent control of brain and core temperatures [4,6,18,19]. While these approaches may be used in specialized hospitals for elective medical procedures, they have limited applicability for aiding in the recovery of neurological emergencies in the field.…”