Use of Prehospital-Induced Hypothermia After Out-of-Hospital Cardiac Arrest: A Survey of the National Association of Emergency Medical Services Physicians

The prehospital management of traumatic brain injury

Traumatic brain injury (TBI) is an important cause of death and disability, particularly in younger populations. The prehospital evaluation and management of TBI is a vital link between insult and definitive care and can have dramatic implications for subsequent morbidity. Following a TBI the brain is at high risk for further ischemic injury, with prehospital interventions targeted at reducing this secondary injury while optimizing cerebral physiology. In the following chapter we discuss the prehospital assessment and management of the brain-injured patient. The initial evaluation and physical examination are discussed with a focus on interpretation of specific physical examination findings and interpretation of vital signs. We evaluate patient management strategies including indications for advanced airway management, oxygenation, ventilation, and fluid resuscitation, as well as prehospital strategies for the management of suspected or impending cerebral herniation including hyperventilation and brain-directed hyperosmolar therapy. Transport decisions including the role of triage models and trauma centers are discussed. Finally, future directions in the prehospital management of traumatic brain injury are explored.

The "ICE" study: feasibility of inexpensive commercial coolers on mobile EMS units

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Physician and nonphysician health-care provider perspectives on resuscitation of suspected drug-related out-of-hospital cardiac arrest

INTRODUCTION

In the United States, out-of-hospital cardiac arrest from drug overdose (OD-OHCA) caused over 38,000 deaths in 2010. A study in Pittsburgh found that OD-OHCA patients differed demographically and in the resuscitation treatments they received, despite identical AHA resuscitation guidelines. We hypothesized that health-care provider perceptions affect decision-making in the treatment of OD-OHCA versus non-OD OHCA.

METHODS

We conducted this survey at the National Association of EMS Physicians 2013 Scientific Assembly. Physicians and non-physician health-care providers were given one of two surveys containing 19 questions pertaining to the respondents' affiliated EMS agencies, the estimated proportion of OD-OHCA as well as the drugs involved, and the respondents' belief about the treatments for OD versus non-OD OHCA.

RESULTS

One hundred ninety-three respondents participated in this survey. Of the 193, 144 (75%) were physicians and 49 (25%) were nonphysicians. Seventy-nine percent of physicians identified current status as a medical director and 76% of nonphysicians identified as a paramedic. Participants estimated the average monthly proportion of all OHCA due to OD to be 9.4%. Participants ranked opioids, alcohol, antidepressants, and benzodiazepines as the most commonly utilized agents in OD-OHCA. The majority of physicians (42%) felt that the incidence of OD-OHCA was not changing while the majority of nonphysicians (53%) felt the incidence was increasing. Eighty-four percent of all respondents reported the use of naloxone during OD-OHCA resuscitation, while 13% reported administering naloxone during non-OD OHCA resuscitation. Eighty-nine percent of physicians and 67% of nonphysicians indicated that OD-OHCA patients had different demographics than non-OD OHCA, with primary reported differences being age, comorbidities, and socioeconomic status. Sixty-three percent of physicians and 71% of nonphysicians felt that OD-OHCA patients should be treated differently, with primary differences being the incorporation of etiology-specific treatments, performing different CPR with a focus on airway support, and transporting earlier.

CONCLUSIONS

When surveyed, physicians and nonphysician providers report perceiving OD-OHCA treatment, outcomes, and patient demographics differently than non-OD OHCA and making different treatment decisions based on these perceptions. This may result in etiology-oriented resuscitation in the out-of-hospital setting, despite the lack of OD-specific resuscitation guidelines.

No benefit to prehospital initiation of therapeutic hypothermia in out-of-hospital cardiac arrest: a systematic review and meta-analysis

OBJECTIVES

The aim of this review was to define the effect of prehospital therapeutic hypothermia (TH) on survival and neurologic recovery in patients who have suffered out-of-hospital cardiac arrest (OHCA).

METHODS

Included in this review are randomized trials assessing the effect of prehospital TH in adult patients suffering nontraumatic OHCA. Trials assessing the effect of in-hospital TH were excluded. Only studies with a low risk of bias were eligible for meta-analysis. A medical librarian searched PubMed, Ovid, EMBASE, Ovid Global Health, the Cochrane Library, Guidelines.gov, EM Association Websites, CenterWatch, IFPMA Clinical Trial Results Portal, CINAHL, ProQuest, and the Emergency Medical Abstracts Database without language restrictions. Clinicaltrials.gov was searched for unpublished studies. Bibliographies were hand searched and experts in the field were queried about other published or unpublished trials. Using standardized forms, two authors independently extracted data from all included trials. Results from high-quality trials were pooled using a random-effects model. Two authors, using the Cochrane risk of bias tool, assessed risk of bias independently.

RESULTS

Of 740 citations, six trials met inclusion criteria. Four trials were at a low risk of bias and were included in the meta-analysis (N=715 patients). Pooled analysis of these trials revealed no difference in overall survival (relative risk [RR]=0.98, 95% CI=0.79 to 1.21) or good neurologic outcome (RR=0.96, 95% CI=0.76 to 1.22) between patients randomized to prehospital TH versus standard therapy. Heterogeneity was low for both survival and neurologic outcome (I2=0).

CONCLUSIONS

Randomized trial data demonstrate no important patient benefit from prehospital initiation of TH. Pending the results of ongoing larger trials, resources dedicated to this intervention may be better spent elsewhere.

Therapeutic hypothermia after out-of-hospital cardiac arrest: evaluation of a regional system to increase access to cooling

BACKGROUND

Therapeutic hypothermia (TH) improves survival and confers neuroprotection in out-of-hospital cardiac arrest (OHCA), but TH is underutilized, and regional systems of care for OHCA that include TH are needed.

METHODS AND RESULTS

The Cool It protocol has established TH as the standard of care for OHCA across a regional network of hospitals transferring patients to a central TH-capable hospital. Between February 2006 and August 2009, 140 OHCA patients who remained unresponsive after return of spontaneous circulation were cooled and rewarmed with the use of an automated, noninvasive cooling device. Three quarters of the patients (n=107) were transferred to the TH-capable hospital from referring network hospitals. Positive neurological outcome was defined as Cerebral Performance Category 1 or 2 at discharge. Patients with non-ventricular fibrillation arrest or cardiogenic shock were included, and patients with concurrent ST-segment elevation myocardial infarction (n=68) received cardiac intervention and cooling simultaneously. Overall survival to hospital discharge was 56%, and 92% of survivors were discharged with a positive neurological outcome. Survival was similar in transferred and nontransferred patients. Non-ventricular fibrillation arrest and presence of cardiogenic shock were associated strongly with mortality, but survivors with these event characteristics had high rates of positive neurological recovery (100% and 89%, respectively). A 20% increase in the risk of death (95% confidence interval, 4% to 39%) was observed for every hour of delay to initiation of cooling.

CONCLUSIONS

A comprehensive TH protocol can be integrated into a regional ST-segment elevation myocardial infarction network and achieves broad dispersion of this essential therapy for OHCA.

Evolution of the Literature Identifying Physicians' Roles in Leadership, Clinical Development, and Practice of the Subspecialty of Emergency Medical Services

Purpose: The 2007 Institute of Medicine report entitled Emergency Medical Services at the Crossroads identified a need for the establishment of physician subspecialty certification in emergency medical services (EMS). The purpose of this study was to identify and explore the evolution of publications that define the role of the physician in EMS systems in the United States.

Methods: Three comprehensive searches were undertaken to identify articles that define the physician's role in the leadership, clinical development, and practice of EMS. Independent reviewers then evaluated these articles to further determine whether the articles identified the physician's role in EMS. Then, identified articles were classified by the type of publication in order to evaluate the transition from a non-peer reviewed to peer-reviewed literature base and an analysis was performed on the differences in the growth between these two groups. In addition, for the peer-reviewed articles, an analysis was performed to identify the proportion of articles that were quantitative versus qualitative in nature.

Results: The comprehensive review identified 1,504 articles. Ninety articles were excluded due to lack of relevance to the US. The remaining 1,414 articles were reviewed, and 194 papers that address the physician's role within EMS systems were identified; 72 additional articles were identified by hand search of references for a total of 266 articles. The percentage of peer-reviewed articles has increased steadily over the past three decades. In addition, the percentage of quantitative articles increased from the first decade to the second and third decades.

Conclusions: This comprehensive review demonstrates that over the past 30 years an evidence base addressing the role of the physician in EMS has developed. This evidence base has steadily evolved to include a greater proportion of peer-reviewed, quantitative literature.

Therapeutic hypothermia for out-of-hospital cardiac arrest: an update for neurosurgeons

BACKGROUND

Neurosurgeons have been familiar with the idea that hypothermia is protective against various types of brain injuries, including traumatic brain injury (TBI). Recent randomized controlled trials, however, have failed to demonstrate the efficacy of therapeutic hypothermia (TH) in patients with TBI. On the other hand, TH becomes popular in the treatment of out-of-hospital cardiac arrest (OHCA) survivors, after randomized controlled trials have shown that survival rate and functional outcome is improved with the use of TH in selected patients. We believe that knowledge on the recent progress in TH for OHCA is useful for neurosurgeons, because feedback of information obtained in the treatment of OHCA may revitalize the interest in TH for neurosurgical disorders, particularly TBI.

METHODS

A review of the literature was conducted with the use of PubMed.

RESULTS

Various cooling techniques and devices have been developed and trialed in the treatment of OHCA survivors, including prehospital cooling with bolus ice-cold saline, endovascular cooling catheters, and new generation surface cooling devices, some of which have already been known to neurosurgeons. The efficacy of these new methods and devices has been demonstrated in many preliminary studies, and phase III trials are also expected.

CONCLUSIONS

Neurosurgeons and critical care medicine physicians pursue the same goal of rescuing the brain from the secondary injury despite the difference in etiology (focal trauma vs. global ischemia), with the presumption that earlier and faster implementation of TH will result in better outcome. Thoughtful application of knowledge and techniques obtained in OHCA to TBI under a rigorously controlled situation will make a small, but significant difference in the outcome of TBI victims.

Educational and research advances stemming from the Academic Emergency Medicine consensus conference in knowledge translation

The 2007 Academic Emergency Medicine (AEM) consensus conference "Knowledge Translation in Emergency Medicine" yielded a number of initiatives in both education and research that directly reflected the conference's published objectives and recommendations. One research initiative, CONCERT, is a national consortium of chronic obstructive pulmonary disease (COPD) investigators who set forth an effort designed to optimize COPD care through the identification of gaps between research and practice in diagnosis and management of the chronic and acute care aspects of this disease. In addition to CONCERT, educational programs designed to identify barriers to evidence implementation and to develop solutions to achieve uptake through multidisciplinary collaboration have emerged that reflect the impact of the consensus conference. This article describes these initiatives and highlights the potential for future innovative opportunities.

Feasibility of intra-arrest hypothermia induction: A novel nasopharyngeal approach achieves preferential brain cooling

AIM

In patients with cardiopulmonary arrest, brain cooling may improve neurological outcome, especially if applied prior to or during early reperfusion. Thus it is important to develop feasible cooling methods for pre-hospital use. This study examines cerebral and compartmental thermokinetic properties of nasopharyngeal cooling during various blood flow states.

METHODS

Ten swine (40+/-4kg) were anesthetized, intubated and monitored. Temperature was determined in the frontal lobe of the brain, in the aorta, and in the rectum. After the preparatory phase the cooling device (RhinoChill system), which produces evaporative cooling in the nasopharyngeal area, was activated for 60min. The thermokinetic response was evaluated during stable anaesthesia (NF, n=3); during untreated cardiopulmonary arrest (ZF, n=3); during CPR (LF, n=4).

RESULTS

Effective brain cooling was achieved in all groups with a median cerebral temperature decrease of -4.7 degrees C for NF, -4.3 degrees C for ZF and -3.4 degrees C for LF after 60min. The initial brain cooling rate however was fastest in NF, followed by LF, and was slowest in ZF; the median brain temperature decrease from baseline after 15min of cooling was -2.48 degrees C for NF, -0.12 degrees C for ZF, and -0.93 degrees C for LF, respectively. A median aortic temperature change of -2.76 degrees C for NF, -0.97 for LF and +1.1 degrees C for ZF after 60min indicated preferential brain cooling in all groups.

CONCLUSION

While nasopharyngeal cooling in swine is effective at producing preferential cerebral hypothermia in various blood flow states, initial brain cooling is most efficient with normal circulation.

Esophageal temperature after out-of-hospital cardiac arrest: an observational study

INTRODUCTION

Out-of-hospital cardiac arrest (OHCA) is a significant cause of death and severe neurological disability. The only post-return of spontaneous circulation (ROSC) therapy shown to increase survival is mild therapeutic hypothermia (MTH). The relationship between esophageal temperature post OHCA and outcome is still poorly defined.

METHODS

Prospective observational study of all OHCA patients admitted to a single centre for a 14-month period (1/08/2008 to 31/09/2009). Esophageal temperature was measured in the Emergency Department and Intensive Care Unit (ICU). Selected patients had pre-hospital temperature monitoring. Time taken to reach target temperature after ROSC was recorded, together with time to admission to the Emergency Department and ICU.

RESULTS

164 OHCA patients were included in the study. 105 (64.0%) were pronounced dead in the Emergency Department. 59 (36.0%) were admitted to ICU for cooling; 40 (24.4%) died in ICU and 19 (11.6%) survived to hospital discharge. Patients who achieved ROSC and had esophageal temperature measured pre-hospital (n=29) had a mean pre-hospital temperature of 33.9 degrees C (95% CI 33.2-34.5). All patients arriving in the ED post OHCA had a relatively low esophageal temperature (34.3 degrees C, 95% CI 34.1-34.6). Patients surviving to hospital discharge were warmer on admission to ICU than patients who died in hospital (35.7 degrees C vs 34.3 degrees C, p<0.05). Patients surviving to hospital discharge also took longer to reach T(targ) than non-survivors (2h 48min vs 1h 32min, p<0.05).

CONCLUSIONS

Following OHCA all patients have esophageal temperatures below normal in the pre-hospital phase and on arrival in the Emergency Department. Patients who achieve ROSC following OHCA and survive to hospital discharge are warmer on arrival in ICU and take longer to reach target MTH temperatures compared to patients who die in hospital. The mechanisms of action underlying esophageal temperature and survival from OHCA remain unclear and further research is warranted to clarify this relationship.

Resuscitation center designation: recommendations for emergency medical services practices

Regionalization of medical resources by designating specialty receiving centers, such as trauma and stroke centers, within emergency medical services (EMS) systems is intended to ensure the highest-quality patient care in the most efficient and fiscally responsible fashion. Significant advances in the past decade such as induction of therapeutic hypothermia following resuscitation from cardiac arrest and a time-driven, algorithmic approach to management of septic patients have created compelling arguments for similar designation for specialized resuscitative interventions. Resuscitation of critically ill patients is both labor- and resource-intensive. It can significantly interrupt emergency department (ED) patient throughput. In addition, clinical progress in developing resuscitation techniques is often dependent on the presence of a strong research infrastructure to generate and validate new therapies. It is not feasible for many hospitals to make the commitment to care for large numbers of critically ill patients and the accompanying investigational activities, whether in the prehospital, ED, or inpatient arena. Because of this, the question of whether EMS systems should designate specific hospitals as "resuscitation centers" has now come center stage. Just as EMS systems currently delineate criteria and monitor compliance for trauma, ST-elevation myocardial infarction (STEMI), and stroke centers, strong logic now exists to develop similar standards for resuscitation facilities. Accordingly, this discussion reviews the current applicable trends in resuscitation science and presents a rationale for resuscitation center designation within EMS systems. Potential barriers to the establishment of such centers are discussed and strategies to overcome them are proposed.

Prehospital therapeutic hypothermia after cardiac arrest--from current concepts to a future standard

Therapeutic hypothermia has been shown to improve survival and neurological outcome after prehospital cardiac arrest. Existing experimental and clinical evidence supports the notion that delayed cooling results in lesser benefit compared to early induction of mild hypothermia soon after return of spontaneous circulation. Therefore a practical approach would be to initiate cooling already in the prehospital setting. The purpose of this review was to evaluate current clinical studies on prehospital induction of mild hypothermia after cardiac arrest. Most reported studies present data on cooling rates, safety and feasibility of different methods, but are inconclusive as regarding to outcome effects.

Prehospital resuscitated cardiac arrest patients: role for induced hypothermia

This article is a support paper for the National Association of EMS Physicians' position paper on induced therapeutic hypothermia in resuscitated cardiac arrest patients. Induced hypothermia is one of the newest treatments aimed at increasing the dismal neurologically intact survival rate for out-of-hospital cardiac arrest patients. Two landmark studies published in 2002 by the New England Journal of Medicine led to the American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care IIa recommendation of cooling unconscious adult patients with return of spontaneous circulation after out-of-hospital cardiac arrest due to ventricular fibrillation to 32 degrees C to 34 degrees C for 12 to 24 hours. Despite many limitations of those studies, the AHA also suggests that this therapy may be beneficial for patients with non-ventricular fibrillation arrests. However, the literature is lacking in answers with regard to the best methods to utilize in cooling patients. While avoiding delay in the initiation of cooling seems logical, the literature is also lacking evidence indicating the ideal time at which to implement cooling. Furthermore, it remains unclear as to which patients may benefit from induced hypothermia. Finally, the literature provides no evidence to support mandating induced hypothermia in the prehospital setting. Given limited prehospital resources, sometimes consisting of only two providers, attention first needs to be given to providing the basic care with the utmost skill. Once the basics are being delivered expertly, consideration can be given to the use of prehospital cooling for the resuscitated cardiac arrest patient in the setting of continued cooling in the hospital.

Prehospital therapeutic hypothermia for comatose survivors of cardiac arrest: a randomized controlled trial

BACKGROUND

Intravenous infusion of ice-cold fluid is considered a feasible method to induce mild therapeutic hypothermia in cardiac arrest survivors. However, only one randomized controlled trial evaluating this treatment exists. Furthermore, the implementation rate of prehospital cooling is low. The aim of this study was to evaluate the efficacy and safety of this method in comparison with conventional therapy with spontaneous cooling often observed in prehospital patients.

METHODS

A randomized controlled trial was conducted in a physician-staffed helicopter emergency medical service. After successful initial resuscitation, patients were randomized to receive either +4 degrees C Ringer's solution with a target temperature of 33 degrees C or conventional fluid therapy. As an endpoint, nasopharyngeal temperature was recorded at the time of hospital admission.

RESULTS

Out of 44 screened patients, 19 were analysed in the treatment group and 18 in the control group. The two groups were comparable in terms of baseline characteristics. The core temperature was markedly lower in the hypothermia group at the time of hospital admission (34.1+/-0.9 degrees C vs. 35.2+/-0.8 degrees C, P<0.001) after a comparable duration of transportation. Otherwise, there were no significant differences between the groups regarding safety or secondary outcome measures such as neurological outcome and mortality.

CONCLUSION

Spontaneous cooling alone is insufficient to induce therapeutic hypothermia before hospital admission. Infusion of ice-cold fluid after return of spontaneous circulation was found to be well tolerated and effective. This method of cooling should be considered as an important first link in the 'cold chain' of prehospital comatose cardiac arrest survivors.

The use of pre-hospital mild hypothermia after resuscitation from out-of-hospital cardiac arrest

Hypothermia has emerged as a potent neuroprotective modality following resuscitation from cardiac arrest. Although delayed hospital cooling has been demonstrated to improve outcome after cardiac arrest, in-field cooling begun immediately following the return of spontaneous circulation may be more beneficial. Cooling in the field following resuscitation, however, presents new challenges, in that the cooling method has to be portable, safe, and effective. Rapid infusion of intravenous fluid at 4 degrees C, the use of a cooling helmet, and cooling plates have all been proposed as methods for field cooling, and are all in various stages of clinical and animal testing. Whether field cooling will improve survival and neurologic outcome remains an important unanswered clinical question.

Perioperative hypothermia: use and therapeutic implications

Perioperative cerebral ischemic insults are common in some surgical procedures. The notion that induced hypothermia can be employed to improve outcome in surgical patients has persisted for six decades. Its principal application has been in the context of cardiothoracic and neurosurgery. Mild (32-35 degrees C) and moderate (26-31 degrees C) hypothermia have been utilized for numerous procedures involving the heart, but intensive research has found little or no benefit to outcome. This may, in part, be attributable to confounding effects associated with rewarming and lack of understanding of the mechanisms of injury. Evidence of efficacy of mild hypothermia is absent for cerebral aneurysm clipping and carotid endarterectomy. Deep hypothermia (18-25 degrees C) during circulatory arrest has been practiced in the repair of congenital heart disease, adult thoracic aortas, and giant intracranial aneurysms. There is little doubt of the protective efficacy of deep hypothermia, but continued efforts to refine its application may serve to enhance its utility. Recent evidence that mild hypothermia is efficacious in out-of-hospital cardiac arrest has implications for patients incurring anoxic or global ischemic brain insults during anesthesia and surgery, or perioperatively. Advances in preclinical models of ischemic/anoxic injury and cardiopulmonary bypass that allow definition of optimal cooling strategies and study of cellular and subcellular events during perioperative ischemia can add to our understanding of mechanisms of hypothermia efficacy and provide a rationale basis for its implementation in humans.

Method of cold saline storage for prehospital induced hypothermia

OBJECTIVE

Research over the last decade has supported the use of cold intravenous (IV) fluid as a method for initiating therapeutic hypothermia in post-cardiac arrest resuscitation. However, prehospital care programs employing this treatment have encountered various difficulties. Barriers to prehospital induced hypothermia (IH) protocols include the lack of effective or economically reasonable methods to maintain cold saline in the field. Validation of a simple method could allow agencies to equip numerous rigs with cold saline. The aim of this study was to determine whether a standard commercial cooler can maintain two 1-L normal saline solution (NSS) bags below 4 degrees C in three different environments.

METHODS

Environments simulating those of an ambulance compartment were created for the experiment. NSS temperatures were continuously recorded inside a standard commercial cooler under one of three scenarios: ambient room temperature (25 degrees C) without ice packs, ambient room temperature with ice packs, and 50 degrees C ambient temperature with ice packs. Four trials under each condition were performed.

RESULTS

In a room-temperature environment without ice packs, the NSS warmed to 4 degrees C in a mean interval of 1 hour 21 minutes. Using room temperature with ice packs, the NSS warmed to 4 degrees C in a mean interval of 29 hours 53 minutes. In a constant hot environment of 50 degrees C, the NSS warmed to 4 degrees C in a mean interval of 10 hours 50 minutes. A significant difference was found between the three environments (log-rank = 17.90, df = 2, p = 0.0001).

CONCLUSIONS

Prehospital refrigeration devices are needed for current and future IH protocols. Low-technology methods in the form of a cooler and ice packs can provide cold saline storage for longer than a full 24-hour shift in a room-temperature ambulance. In extremely hot conditions, 4 degrees C NSS can be maintained for nearly 11 hours using this method. This model exhibits an economical, easily deployable cold saline storage unit.

Prehospital cooling with hypothermia caps (PreCoCa): a feasibility study

BACKGROUND

Animal studies suggest that the induction of therapeutic hypothermia in patients after cardiac arrest should be initiated as soon as possible after ROSC to achieve optimal neuroprotective benefit. A "gold standard" for the method of inducing hypothermia quickly and safely has not yet been established. In order to evaluate the feasibility of a hypothermia cap we conducted a study for the prehospital setting.

METHODS AND RESULTS

The hypothermia cap was applied to 20 patients after out-of-hospital cardiac arrest with a median of 10 min after ROSC (25/75 IQR 8-15 min). The median time interval between initiation of cooling and hospital admission was 28 min (19-40 min). The median tympanic temperature before application of the hypothermia cap was 35.5 degrees C (34.8-36.3). Until hospital admission we observed a drop of tympanic temperature to a median of 34.4 degrees C (33.6-35.4). This difference was statistically significant (P < 0.001). We could not observe any side effects related to the hypothermia cap. 25 patients who had not received prehospital cooling procedures served as a control group. Temperature at hospital admission was 35.9 degrees C (35.3-36.4). This was statistically significant different compared to patients treated with the hypothermia cap (P < 0.001).

CONCLUSIONS

In summary we demonstrated that the prehospital use of hypothermia caps is a safe and effective procedure to start therapeutic hypothermia after cardiac arrest. This approach is rapidly available, inexpensive, non-invasive, easy to learn and applicable in almost any situation.

Burning issues: early cooling of the brain after resuscitation using burn dressings. A proof of concept observation

AIM OF THE STUDY

Early cooling of resuscitated patients improves neurological outcome. Out-of hospital initiation of cooling is uncommon however for mainly practical reasons. Using burn dressings in the out-of-hospital care could initiate brain cooling in an early stage and therefore be of value; the method is easily adaptable by ambulance crews. The influence of burn dressings on brain temperature is however unknown. We determined tympanic temperature changes as proxy for brain temperature in healthy volunteers after the application of cooling dressings to face and neck as a proof of concept study.

METHOD

In 10 healthy human volunteers tympanic temperatures were measured in 30s intervals before, during and after the application of burn-dressings, special trauma burn-care dressings that are designed for the acute treatment of skin burns (Burnshield emergency burn care sterile trauma burn dressings, Burnshield Ltd., Wadefield, South Africa) for the duration of 20min for each episode.

RESULTS

In all study subjects the tympanic temperature was significantly lowered after 20min of the application of the burnshields. The mean difference between baseline and 2nd half of the exposure period was 0.43 degrees C (p<0.0001), ranging from 0.10 to 1.18 degrees C.

CONCLUSION

Burn dressings could be of value in the early initiation of brain cooling in resuscitated patients. This study warrants further research to the effect of burnshield dressings on neurological activity and the effect on outcome after resuscitation.