Hypothermia in cardiac surgery

Abstract

Since the beginning of the era of cardiac surgery hypothermia remains a mainstay in perioperative management. This role is increasingly being questioned because of many disadvantages and the lack of evidence of advantages. Using modern techniques of perfusion and myocardial protection as well as improved surgical techniques the results with normothermia seem to be comparable. The importance of hypothermia in present day cardiac surgery is discussed with respect to myocardial and cerebral protection.

Improved contractility with tepid modified full blood cardioplegia compared with cold crystalloid cardioplegia in a piglet model

“…Moderate hypothermia is commonly used during congenital heart surgery and enables an adequate systemic oxygenation even under low-flow conditions. In the absence of circulatory arrest, mild hypothermia appears to be an advantage for neuroprotection only but not myocardial protection [5]. If further reduction of myocardial temperature occurs, excessive leftward shifting of the oxyhaemoglobin curve inhibits cellular oxygen uptake, which counteracts the positive effect of blood cardioplegia as an energy deliverer.…”

“…Blood, unlike crystalloid solutions, carries oxygen, nutrients and energy to the cells and organs. It combines natural buffering capacity and ideal colloid-osmotic pressure with physiological rheology, which has a positive effect on the degree of oedema [3][4][5]. Additionally, high-energy phosphate, oxygen and anti-oedematous substrates are delivered to myocardial tissue, and free radicals and degradation products are washed out by repeated administration of blood cardioplegia every 20 min.…”

“…In order to reduce possible deleterious systemic side-effects of crystalloid solutions along with hypothermia [5], Calafiore et al [4] have introduced their variant of full blood cardioplegia composed of blood mixed with potassium and magnesium, which has gained wide acceptance for normothermic use in adult cardiac surgery since the end of the 1990s. The lack of crystalloid solutions and no need for a heat exchanger reducing CPB priming would predispose full blood cardioplegia especially for use in children.…”

Neuromonitoring und Neuroprotektion in der Kardioanästhesie

“…2°C niedriger bzw. hö her als die jugularvenöse Temperatur lie gen [48], die der beste Surrogatparameter für die zerebrale Temperatur darstellt [54]. Leider war der Ort der Temperaturmes sung nicht Gegenstand des Fragebogens, sodass Aussagen zu Häufigkeitsverteilung und Präferenz der Temperaturmessorte nicht getroffen werden können.…”