Prehospital postresuscitation induced hypothermia (IH) has been shown to reduce neurological complications in comatose cardiac-arrest survivors. Retrofitting ambulances to include equipment appropriate to initiate hypothermia, such as refrigeration units for cooled saline, is expensive. The objective of this nonhuman subject research study was to determine if inexpensive, commercially available coolers could, in conjunction with five reusable ice packs, keep two 1 L bags of precooled 0.9% normal saline solution (NSS) at or below 4°C for an average shift of eight to 12 hours in a real-world environment, on board in-service Emergency Medical Service (EMS) units, over varying weather conditions in all seasons.

The coolers were chosen based on availability and affordability from two nationally available brands: The Igloo MaxxCold (Igloo Products Corp., Katy, Texas USA) and Coleman (The Coleman Company, Wichita, Kansas USA). Both are 8.5 liter (nine-quart) coolers that were chosen because they adequately held two 1 L bags of saline solution, along with the reusable ice packs designated in the study design, and were small enough for ease of placement on ambulances. Initial testing of the coolers was conducted in a controlled environment. Thereafter, each EMS unit was responsible to cool the saline to less than 4°C prior to shift. Data were collected by emergency medical technicians, paramedics, and resident physicians working in seven different ambulance squads. Data analysis was performed using repeated measurements recorded over a 12-hour period from 19 individual coolers and were summarized by individual time points using descriptive statistics.

Initial testing determined that the coolers maintained temperatures of 4°C for 12 hours in a controlled environment. On the ambulances, results based on the repeated measurements over time revealed that the saline solution samples as defined in the protocol, remained consistently below 4°C for 12 hours. Utilizing the lower bound of the 2-sided 95% exact binomial confidence intervals, there was less than a five percent chance that saline samples could not be maintained below 4°C for 12 hours, even during the summer months.

Simple, commercially available coolers can maintain two 1 L bags of 0.9% NSS at 4°C for 12 hours in ambulances in varying environmental conditions. This suggests that EMS agencies could inexpensively initiate prehospital IH in appropriate cases.

KaneKE , TomshoRJ , PheasantK , StaufferT , SchoenfeldtB , HamiltonS , KainT , KaneBG . The “ICE” Study: Feasibility of Inexpensive Commercial Coolers on Mobile EMS Units. Prehosp Disaster Med. 2014;29(3):1-8.

Inducing mild hypothermia in survivors of cardiac arrest has been demonstrated to improve outcomes. Despite this, other studies have found that few resuscitation physicians have used hypothermia in clinical practice. The objective of this study was to characterize the use of induced hypothermia by Canadian emergency physicians.

An internet-based survey was distributed to all members of the Canadian Association of Emergency Physicians (CAEP). Participants were asked about their experience with, methods for and barriers to inducing hypothermia.

Of the 1328 CAEP members surveyed, 247 (18.6%) responded, with the majority working in academic centres (60.3%). Ninety-five out of 202 respondents (47.0%, 95% confidence interval [CI] 40.8%–53.2%) indicated that they had induced hypothermia in clinical practice and 86 of 212 (40.6%, 95% CI 34.0%–47.2%) worked in a department that had a policy or protocol for the use of induced hypothermia. The presence of a departmental policy or protocol was strongly associated with the use of induced hypothermia (unadjusted odds ratio 10.5, 95% CI 5.3–20.8). Barriers against induced hypothermia cited by respondents included a lack of institutional policies and protocols (38.9%), and of resources (29.4%). Lack of support from consultants was relatively uncommon (8.7%) in Canadian practice.

Only one-half of Canadian emergency physicians report that they have used therapeutic hypothermia in practice. Emergency departments should develop policies or protocols for inducing hypothermia in cardiac arrest survivors to optimize patient outcomes.

Several randomized controlled trials have suggested that mild induced hypothermia may improve neurologic outcome in comatose cardiac arrest survivors. This systematic review of randomized controlled trials was designed to determine if mild induced hypothermia improves neurologic outcome, decreases mortality, or is associated with an increased incidence of adverse events.

The following databases were reviewed: Cochrane Controlled Trials Register (Issue 4, 2005), MEDLINE (January 1966 to November 2005), EMBASE (1980 to November 2005), CINAHL (1982 to November 2005) and Web of Science (1989 to November 2005). For each included study, references were reviewed and the primary author contacted to identify any additional studies.

Studies that met inclusion criteria were randomized controlled trials of adult patients (>18 years of age) with primary cardiac arrest who remained comatose after return of spontaneous circulation. Patients had to be randomized to mild induced hypothermia (32°C-34°C) or normothermia within 24 hours of presentation. Only studies reporting pre-determined outcomes including discharge neurologic outcome, mortality or significant treatment-related adverse events were included. There were no language or publication restrictions.

Four studies involving 436 patients, with 232 cooled to a core temperature of 32°C-34°C met inclusion criteria. Pooled data demonstrated that mild hypothermia decreased inhospital mortality (relative ratio [RR] 0.75; 95% confidence interval [CI], 0.62-0.92) and reduced the incidence of poor neurologic outcome (RR 0.74; 95% CI, 0.62-0.84). Numbers needed to treat were 7 patients to save 1 life, and 5 patients to improve neurologic outcome. There was no evidence of treatment-limiting side effects.

Therapeutically induced mild hypothermia decreases in-hospital mortality and improves neurologic outcome in comatose cardiac arrest survivors. The possibility of treatment-limiting side effects cannot be excluded.