How cool are your “ice-cold” infusions?

Abstract

Therapeutic hypothermia is increasingly used in the early postresuscitation phase already in the prehospital environment. One of the most utilized methods is to give ice-cold intravenous fluids approximately 30 ml/kg as a rapid infusion.1Kämäräinen A. Virkkunen I. Tenhunen J. Yli-Hankala A. Silfvast T. Prehospital therapeutic hypothermia for comatose survivors of cardiac arrest: a randomised controlled trial.Acta Anaesthesiol Scand. 2009; 53: 900-907Crossref PubMed Scopus (111) Google Scholar, 2Hammer L. Vitrat F. Savary D. et al.Immediate prehospital hypothermia protocol in comatose survivors of out-of-hospital cardiac arrest.Am J Emerg Med. 2009; 27: 570-573Abstract Full Text Full Text PDF PubMed Scopus (40) Google Scholar Fluids are kept cold in ambulances in traditional iceboxes3Kampmeyer M. Callaway C. Method of cold saline storage for prehospital induced hypothermia.Prehosp Emerg Care. 2009; 13: 81-84Crossref PubMed Scopus (6) Google Scholar or in commercial boxes specifically designed for this purpose. Prehospital therapeutic hypothermia was introduced in Helsinki Emergency Medical Service in November 2009. ChillCore® Case (Thomas EMS, Salt Lake City, UT, USA) was chosen as the device to keep the fluids cool. The chamber temperature of the box was preset to be +2 °C. We allow temperature variation between +1 and +3 °C and the chamber temperature is monitored via a screen in front of the case. Preset temperature is changed if indicated when conducting two daily checks. The case contains two 1000 ml bags of Ringer acetate with pressure bags on them and two 500 ml bags of Ringer acetate without pressure bags. After the introduction of the ChillCore® Case into clinical practise we soon noticed that the infusion bags inside the case felt warmer than the temperature value shown in the screen. We conducted control temperature measurements of infusion bags in two ChillCore® Cases using Fluke 289 True-rms Industrial Logging Multimeter (Fluke Corporation, Everett, WA, USA). The original temperature of the bags was +3.2 °C when placed into the ChillCore® Case. After the first measurement on day 1 the preset temperature of case number 1 was changed from +2 to +0 and 4 h for stabilisation was allowed before the second measurement. After the second measurement all infusion bags were repacked into the two cases so that bags were as precisely as possible against the cooling plate and the pressure bags covering 1000 ml bags were removed for the third measurement that took place on day 2. Additionally temperature measurement of an empty case (case number 3) was conducted. The results are presented in Table 1. We found that the actual temperature of intravenous fluids was considerably higher than the preset values and values shown by the own thermometer of the case. Some infusion bags were so warm (up to 11.4 °C) that infusing these to a patient is not likely to cause desired hypothermic effect. Instead it may predispose patients to possible harmful effects of volume loading.Table 1Temperatures of infusion bags inside the cooling case.Measurement (day; h)ChillCore® Case (case number)Preset temperature (°C)Screen temperature (°C)Real temperature (°C)Ringer bag (bag size)Day 1; 09:301+2+1+10.2500 mlDay 1; 09:302+2+1+8.6500 mlDay 1; 13:301+0+0+6.3500 mlDay 1; 13:301+0+0+11.41000 mlaWith a pressure bag on.Day 2; 09:151+2+1+6.0500 mlDay 2; 09:151+2+1+7.01000 mlDay 2; 09:152+2+1+5.5500 mlDay 2; 09:152+2+1+6.71000 mlDay 2; 09:153+0+0−1.5 to +4.5bTemperature values of an empty case in various parts inside the case.–a With a pressure bag on.b Temperature values of an empty case in various parts inside the case. Open table in a new tab When infusion of ice-cold intravenous fluids is used to induce therapeutic hypothermia we recommend regular control temperature measurements of infusion bags. It is essential that the cold chain of fluids is maintained until the fluids reach the patient. The manufactures should improve the devices so that maximally cold stable temperature of fluids without freezing (e.g. +0.5 to +2 °C) would be guaranteed in all circumstances. None.