In-hospital hypothermia

Abstract

Mild therapeutic hypothermia after cardiac arrest has become standard in post-resuscitation care in many hospitals as it is recommended by current guidelines. The last update of guidelines by the European Resuscitation Council on post-cardiac arrest treatment in 2010 recommends hypothermia for every patient after cardiac arrest who remains unconscious after cardiac arrest [1]. In addition to milestone trials [2-4], current published retrospective data from the large Finnish registry showed in a large group of patients a significant reduction of hospital mortality of survivors of out-of-hospital cardiac arrest after implementation of hypothermia [5]. The mild therapeutic hypothermia procedure after cardiac arrest can be divided into three phases: introduction, maintenance and rewarming. The cooling techniques and devices to induce cooling of the cardiac arrest survivor can be separated into three main groups: conventional cooling (no device), non-invasive (surface) systems, and invasive (intravascular) systems (Table ​(Table11). Table 1 Cooling techniques Conventional cooling methods The easiest way to induce hypothermia after cardiac arrest is by using cold saline (for example, 0.9% NaCl solution), crushed ice or ice bags. Kim and colleagues reported the safety and efficacy of the administration of up to 2 litres of 4°C cold saline to the patient after hospital admission [6]. Others published data using 30 ml/kg body weight of saline 0.9% NaCl or Ringer's lactate combined sometimes with ice bags, which led to an acceptable reduction of the temperature [7-10]. Furthermore cold saline as well as other methods like cooling caps and helmets have been evaluated for induction mainly in the preclinical setting [4,11,12]. Kliegel and colleagues pointed out that cold infusion alone is effective for induction but not for tight maintenance of the target temperature [13]. However, in at least one trial the combination of cold saline and ice packs was proven to be effective even to maintain temperature [7]. Focusing on the induction in the in-hospital setting, most authors rank cold saline and crushed ice more as effective adjuvant methods to be combined with a computer-controlled cooling device [10]. The big advantage of cold saline is its availability at almost every place in the hospital if provided and the low costs. Following the data available concerning different amounts of saline administered to the patient, a median amount of 1 to 2 litres of saline seems safe after cardiac arrest. To maintain target temperature with cold saline and ice bags seems to require a high binding of personnel method without a very precise influence on the central body temperature.