Brief description of patient problem/setting (summarize the case very briefly)
While viewing a patient come into the emergency department for a cardiac arrest, you investigate different modalities that can used to extend neurological outcomes and survival rates of affected patients before they hit the ambulance doors of the ED. One of the longer standing attending physicians talks about cooling techniques that can possibly be utilized.
Search Question: Clearly state the question (including outcomes or criteria to be tracked)
In adults with out-of-hospital cardiac arrest, does prehospital therapeutic hypothermia compared to standard care without prehospital hypothermia improve neurological outcomes and survival rates?
Question Type: What kind of question is this? (boxes now checkable in Word)
☐Prevalence ☐Screening ☐Diagnosis
☐Prognosis ☐Treatment ☒Harms
Assuming that the highest level of evidence to answer your question will be meta-analysis or systematic review, what other types of study might you include if these are not available (or if there is a much more current study of another type)? Please explain your choices.
– If meta-analysis or systematic review are not available, randomized controlled clinical trials will also offer great supporting evidence as they are carefully planned experiments, reduce the potential for bias, and allow for comparison between intervention and control groups.
– Cohort studies could also be used since they allow to follow the patients who have already received a particular treatment forward over time. This is not as reliable as randomized controlled clinical trials since patients might differ in ways other than in the variable that is being observed.
PICO search terms:
| P | I | C | O |
| Out of hospital cardiac arrest | Prehospital therapeutic hypothermia | Standard of care without prehospital hypothermia | Neurological outcomes |
| Patients undergoing cardiac arrest | Targeted temperate management | Standard of care | Survival rates |
| OHCA |
Search tools and strategy used:
Please indicate what data bases/tools you used, provide a list of the terms you searched together in each tool, and how many articles were returned using those terms and filters.
Explain how you narrow your choices to the few selected articles.
Results found:
TRIP Database
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia – 25
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia AND Standard of care – 8
PubMed
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia (last 10 years) – 99
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia (last 10 years and Meta-analysis) – 10
Google Scholar
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia – 23,000
- Out of hospital cardiac arrest AND Prehospital therapeutic hypothermia (last 10 years) – 16,000
Most of the articles I chose were systematic reviews and meta-analysis that dealt with my topic. Unfortunately, there have not been too many more recent articles from 2020 and on, but there were all within the 10-year gap I gave myself to choose articles from. One of the articles I chose was a retrospective chart review that was taken from a large metropolitan EMS system in Columbus, OH. I felt like including actual cases from an American city was important. As an aside, I saw other more targeted randomized control trials like the RINSE trial and the PRINCESS trial that were initiated in Australia and European countries that looked at the effects of OHCA and whether therapeutic hypothermia significantly improved neurological outcomes in cardiac arrest patients. I did not use them because I wanted to keep the articles more situated in the United States, but I wanted to bring them up in my PICO.
Identify at least 4 articles (or other appropriate reputable sources) that answer your specific question with the highest available level of evidence (you will probably need to look at more than 4 articles to get the 4 most focused and highest-level articles to address your question). Please make sure that they are Medline indexed.
Please post the citation and abstract for each article (to include the journal and authors’ names and date) and say why you chose it.
Please also note what kind of article it is (e.g. meta-analysis, cohort study, or independent blind comparison with gold standard of diagnosis, etc.).
At the bottom of each abstract, please comment on what your key points are from this article (including any points or concepts included in the article, but not present in the abstract – i.e. make the concepts understandable to the reader)
Please note that if the evidence is not in the abstract, you must clearly summarize the evidence in your posting.
| Citation: Lindsay, P. J., Buell, D., & Scales, D. C. (2018). The efficacy and safety of pre-hospital cooling after out-of-hospital cardiac arrest: a systematic review and meta-analysis. Critical care (London, England), 22(1), 66. https://doi.org/10.1186/s13054-018-1984-2 |
| Type of article: Systematic review and meta-analysis |
| Abstract Background: Mild therapeutic hypothermia (TH), or targeted temperature management, improves survival and neurological outcomes in patients after out-of-hospital cardiac arrest (OHCA). International guidelines strongly support initiating TH for all eligible individuals presenting with OHCA; however, the timing of cooling initiation remains uncertain. This systematic review and meta-analysis was conducted with all available randomized controlled trials (RCTs) included to explore the efficacy and safety of initiating pre-hospital TH in patients with OHCA. Methods: The MEDLINE and Cochrane databases were searched from inception to October 2017. Inclusion criteria for full-text review included RCTs comparing pre-hospital TH with no pre-hospital TH after cardiac arrest, patients > 14 years of age with documented cardiac arrest from any rhythm, and outcome data that included survival to hospital discharge and temperature at hospital arrival. Results of retrieved studies were compared through meta-analysis using random effects modelling. Results: A total of 10 trials comprising 4220 patients were included. There were no significant differences between the two arms for the primary outcome of neurological recovery (risk ratio [RR] 1.04, 95% CI 0.93–1.15) or the secondary outcome of survival to hospital discharge (RR 1.01, 95% CI 0.92–1.11). However, there was a significantly lower temperature at hospital arrival in patients receiving pre-hospital TH (mean difference − 0.83, 95% CI − 1.03 to − 0.63). Pre-hospital TH significantly increased the risk of re-arrest (RR 1.19, 95% CI 1.00 to 1.41). No survival differences were observed among subgroups of patients who received intra-arrest TH vs post-arrest TH or who had shockable vs non-shockable rhythms. Conclusions: Pre-hospital TH after OHCA effectively decreases body temperature at the time of hospital arrival. However, it does not improve rates of survival with good neurological outcome or overall survival and is associated with increased rates of re-arrest. |
| Key Points: This systematic review and meta-analysis included 10 studies from the MEDLINE and Cochrane Library databases2129 patients were part of the treatment arm which used cooling solution to induce therapeutic hypothermia prior to getting to the hospital2091 patients were allocated to the control arm of the study which did not use any cooling solutions prior to getting to the hospitalThe type of cooling solution that was used in the treatment arm was an infusion of a cold solution, normal saline or Ringer’s lactate (depending on the study)There were no differences in the rates of favorable neurologic outcomes during hospital discharge between either the treatment or the control armsFor the variable of the patient’s survival to the hospital, both arms showed similar ratesRates of re-cardiac arrest were higher in patients that had the cooling measures initiated versus the patients that did not have treatment initiated |
| Why I chose it: I chose this article because the sample size of patients was evenly split down the middle, and there was a very large sample that was used. This article also talked about patients converting to re-arrest after getting prehospital therapeutic hypothermia. The authors of those studies mentioned the rapid infusion of fluid resulted in a volume overload which led to the patient’s re-arrest. |
| Citation: Nie, C., Dong, J., Zhang, P., Liu, X., & Han, F. (2016). Prehospital therapeutic hypothermia after out-of-hospital cardiac arrest: a systematic review and meta-analysis. The American journal of emergency medicine, 34(11), 2209–2216. https://doi.org/10.1016/j.ajem.2016.09.007 |
| Type of article: Systematic review and meta-analysis |
| Abstract Background: The effectiveness and safety of the infusion of ice-cold fluids for prehospital hypothermia in cardiac arrest victims are unclear. This study assessed its effects in adult victims of out-of-hospital cardiac arrest. Methods: An online search of PubMed and Cochrane Library databases was performed. Cooling methods were limited to ice-cold fluid perfusion. Randomized controlled trials were included in this review. The main outcomes were body temperature at hospital arrival, survival to hospital discharge, neurological recovery, incidence of pulmonary edema, and the rate of rearrest. Results: Among 1155 citations, 5 studies were included in this meta-analysis. The pooled analysis of these studies revealed no differences in survival to hospital discharge, favorable neurological outcomes, and incidence of pulmonary edema between the treatment group and control group. There were significant differences in body temperature at hospital arrival (I2=0.0%, χ2=2.58, MD=−0.760, 95% confidence interval=−0.938 to−0.581, P b .001) and the rate of rearrest (I2=0.0%, χ2 = 0.69, 95% confidence interval = 1.109 to 1.479, P = .031). Conclusions: Prehospital therapeutic hypothermia induced by intravenous infusion of ice-cold fluids in patients with out-of-hospital cardiac arrest decreased body temperature at hospital arrival but did not improve survival to hospital discharge and favorable neurological outcomes. Ice-cold fluid infusion did not increase the incidence of pulmonary edema but increased the incidence of rearrests. |
| Key Points: This article included 5 studies that included 524 participants273 participants were part of the treatment group that included the cooling measures251 participants were part of the control groupPrehospital therapeutic hypothermia was induced after return of spontaneous circulation (ROSC) in all studiesThe cooling methods were 4°C isotonic sodium chloride solution infusion in 2 studies and ice-cold lactated Ringer’s solution infusion in 3 studiesStudies found that there was no significant difference in survival to hospital discharge between the treatment group and the control group In regards to neurological outcomes, there was also no difference seen between either groupThis study included incidence of pulmonary edema as a variable, in which there was no difference between the treatment or the control groupsThree studies reported outcomes in regards to re-arrest. As mentioned in the previous study, the incidence of re-arrest was higher in the treatment group than that of the control group |
| Why I chose it: I chose this article because it re-verified what was previously discussed in the first study. Many of the same points were talked about, as well as discussing if the patient suffered from pulmonary edema during treatment. Articles that were used in this study said that re-arrest frequently occurred when using therapeutic hypothermia (up to a rate of 36%) and I thought that was very interesting to include. |
| Citation: Szarpak, L., Filipiak, K. J., Mosteller, L., Jaguszewski, M., Smereka, J., Ruetzler, K., Ahuja, S., & Ladny, J. R. (2021). Survival, neurological and safety outcomes after out of hospital cardiac arrests treated by using prehospital therapeutic hypothermia: A systematic review and meta-analysis. The American journal of emergency medicine, 42, 168–177. https://doi.org/10.1016/j.ajem.2020.02.019 |
| Type of article: Systematic review and meta-analysis |
| Abstract Objective: Survival after pre-hospital cardiac arrest (PHCA) remains low. Pre-hospital therapeutic hypothermia (PTH) is believed to improve patient’s outcomes, but data on efficacy and safety remains scarce. Herein, we aimed to assess the influence of PTH on survival, neurological outcome, and adverse effects in patients with PHCA. Materials and methods: A literature search of PubMed CENTRAL, EMBASE, and The Cochrane Central Register of Controlled Trials databases from inception to August 2019 was conducted and retrieved abstracts were independently assessed by two reviewers. The primary outcome was survival to hospital discharge with a favorable neurological outcome. Secondary outcomes were survival to hospital discharge and temperature upon hospital admission. The safety outcomes included pulmonary edema and recurrent arrest during transport to the hospital. We also considered a favorable neurological function to hospital discharge or longest post arrest follow-up. Results: Eleven studies including 4891 patients were included into final analysis. The survival to hospital discharge did not differ between PTH and control group (RR 1.02; 95%CI 0.93 to 1.12). Among 4891 participants (2466 in PTH group and 2425 in control group), 1087 participants (564 vs. 523, respectively) had a favorable neurological outcome. Pulmonary edema occurred in 320 cases in PTH group and 273 in control group with significant heterogeneity (RR 0.90, 95%CI 0.59–1.38; I2 = 80%). The pooled results showed a significant difference in rearrests between the PTH and control group (RR 1.19; 95%CI 1.00 to 1.42). Conclusion: Our analysis demonstrates that PTH does not improve survival at discharge or neurological outcome. |
| Key Points: This systematic review and meta-analysis looked at 4,891 patients across 11 studiesThe PTH (prehospital therapeutic hyperthermia) group, also known as the treatment group, consisted of 2,466 participants The control group had 2,425 participantsBoth groups had the same rate for neurological outcomes during discharge from the hospitalThe overall survival rate did not differ significantly between both groupsMore than half the studies that were looked at showed that initiating prehospital therapeutic hyperthermia led to re-arrest during transport to the hospital for the patient |
| Why I chose it: I chose this article because it was the most recent study I could find on the subject and it had the largest sample size that was split down the middle. The article showed that even with newer updated data, the same information was found as before in regards to prehospital therapeutic hyperthermia and I really enjoyed reading about that. |
| Citation: Cortez, E., Panchal, A. R., Davis, J., Zeeb, P., & Keseg, D. P. (2015). Clinical Outcomes in Cardiac Arrest Patients Following Prehospital Treatment with Therapeutic Hypothermia. Prehospital and disaster medicine, 30(5), 452–456. https://doi.org/10.1017/S1049023X15004987 |
| Type of article: Retrospective Chart Review |
| Abstract Introduction: Recent studies have brought to question the efficacy of the use of prehospital therapeutic hypothermia for victims of out-of-hospital cardiac arrest (OHCA). Though guidelines recommend therapeutic hypothermia as a critical link in the chain of survival, the safety of this intervention, with the possibility of minimal treatment benefit, becomes important. Hypothesis/Problem This study examined prehospital therapeutic hypothermia for OHCA, its association with survival, and its complication profile in a large, metropolitan, fire-based Emergency Medical Services (EMS) system, where bystander cardiopulmonary resuscitation (CPR) and post-arrest care are in the process of being optimized. Methods: This evaluation was a retrospective chart review of all OHCA patients with return of spontaneous circulation (ROSC) treated with therapeutic hypothermia, from January 1, 2013 through November 30, 2013. The primary outcomes were the proportion of patients with initiation of prehospital therapeutic hypothermia with survival to hospital admission, the proportion of patients with initiation of prehospital therapeutic hypothermia with survival to hospital discharge, and the complication profile of therapeutic hypothermia in this population. The complication profile included several clinical, radiographic, and laboratory parameters. Exclusion criteria included: no prehospital therapeutic hypothermia initiation; no ROSC; and age of 17 year old or younger. Results: Fifty-one post-cardiac arrest patients were identified that met inclusion criteria. The mean age was 61 years (SD=14.7 years), and 33 (72%) were male. The initial rhythm was ventricular fibrillation or pulseless ventricular tachycardia in 17 (37%) patients, and bystander CPR was performed in 28 (61%) patients with ROSC. Thirty-nine (85%) patients survived to hospital admission. Twenty-one patients (48%; 95% CI, 33-64) were administered vasopressors, 10 patients (24%; 95% CI, 10-37) were administered diuretics, and 19 patients (44%; 95% CI, 29-60) were administered antibiotics. Initial chest radiograph (CXR) findings were normal in 12 (29%) patients. Overall, 13 (28%; 95% CI, 15-42) study patients survived to hospital discharge. Conclusion: Recent reports have questioned the efficacy and safety of prehospital therapeutic hypothermia. In this evaluation, in the setting of unstandardized post-arrest care, 85% of the patients survived to hospital admission and 28% survived to hospital discharge, with a complication profile which was similar to that noted in other studies. This suggests that further evidence may be needed before EMS systems stop administering therapeutic hypothermia to appropriately selected patients. In less-optimized systems, therapeutic hypothermia may still be an essential link in the chain of survival. |
| Key Points: This retrospective cohort study had 51 post-cardiac arrest patients in a large metropolitan American city (Columbus, OH)All patients were over the age of 18 and all of them received prehospital therapeutic hypothermia that was initiated after ROSC with ice-cold normal salineThe mean age was 61 years old and 72% of the patients were maleOf the 51 patients who were given the saline, 39 made it to emergency department for hospital admissionOf the total cohort that was discussed, 13 patients survived to be discharged from the hospital |
| Why I chose it: I chose this article because I wanted an article that was not a systematic review or meta-analysis. I wanted to pick an article that showed actual patients in an American city that went through prehospital therapeutic hyperthermia and what happened to them. Although the sample size was small, the same data was extrapolated as the other articles that had much bigger sample sizes. 85% of the fifty-one patients made it to the hospital, and only 28% survived to discharge. These numbers mirrored the other ones that were taken from the systematic reviews and meta-analysis, showing that no matter where you initiated the treatment, the same outcomes were going to happen |
What is the clinical “bottom line” derived from these articles in answer to your question?
The survival rate after a cardiac arrest is very small. There has been literature from decades ago that said administering cold fluids after return of spontaneous circulation increases survival rates of cardiac arrest. After reading through many different articles and studies, this is simply not the case. Neurological outcomes and survival rates were the same between treatment and control groups. The rate of re-arrest was higher in patients who did receive prehospital therapeutic hypothermia (PTH). If I was asked whether PTH was a viable option in prolonging the survival rate in a patient with an out of hospital cardiac arrest, I would say it was not. The rate of re-arrest for PTH is too high and is just not worth it.
