Public health impact of full implementation of therapeutic hypothermia after cardiac arrest

AIM: Induced hypothermia improves outcomes in patients resuscitated successfully after cardiac arrest due to ventricular fibrillation. However, a minority of US physicians currently use the therapy. The aim of this study was to project the public health impact of implementing hypothermia in all eligible US out-of-hospital cardiac arrest (OHCA) survivors. METHODS: The number of OHCA patients expected to have a good outcome after hypothermia was calculated using a linear model. Literature-derived input variables included OHCA incidence rates and US 2000 census data, percent with return to spontaneous circulation (ROSC), percent eligible for hypothermia, and the expected benefit from hypothermia. Sensitivity analyses were performed to calculate a plausible range around the reference case. RESULTS: An additional 2298 US patients per year are expected to have a good neurological outcome if US physicians implement hypothermia fully in comatose survivors of OHCA. The two-way sensitivity analyses found that this number ranged from 766 to 5171 patients. This model is similarly sensitive to varying the incidence of OHCA, percent with ROSC, percent of patients eligible for hypothermia, and the number needed to treat. CONCLUSIONS: If US physicians adopt therapeutic hypothermia fully in eligible patients with OHCA, 2298 additional patients per year would be expected to achieve a good neurological outcome, a substantial public health impact. Barriers to adoption should be researched and addressed to increase acceptance and use by US physicians.     

Relationship between blood, nasopharyngeal and urinary bladder temperature during intravascular cooling for therapeutic hypothermia after cardiac arrest

Objectives

Therapeutic hypothermia improves survival and neurological outcome in patients successfully resuscitated after cardiac arrest. Accurate temperature control during cooling is essential to prevent cooling-related side effects.

Methods

Prospective observational study of 12 patients assessed during therapeutic hypothermia (32-34 °C) achieved by intravascular cooling following cardiac arrest. Simultaneous temperature measurements were taken using a Swan-Ganz catheter (blood temperature BLT), nasopharyngeal probe (nasopharyngeal temperature NPT) and the urinary bladder catheter (urinary bladder temperature UBT). A total of 1728 measurements (144 measurements per patient) were recorded over a 48-h period and analyzed. Blood temperature was considered as the reference measurement.

Results

Temperature profiles obtained from BLT, NPT and UBT compared with the use of analysis of variance did not differ significantly. Pearson correlation revealed that the correlation between BLT and NPT as well as BLT and UBT was statistically significant (r = 0.96, p < 0.001 and r = 0.95, p < 0.001, respectively). Bland-Altman analysis proved that the agreement between all measurements was satisfactory and the differences were not clinically important.

Conclusions

In 12 post-cardiac arrest patients undergoing intravascular cooling, both nasopharyngeal and urinary bladder temperature measurements were similar to blood temperatures measured using a pulmonary artery catheter.     

A history of smoking is associated with improved survival in patients treated with mild therapeutic hypothermia following cardiac arrest

Objectives

To assess the association between smoking and survival with a good neurologic outcome in patients following cardiac arrest treated with mild therapeutic hypothermia (TH).

Methods

We conducted a retrospective observational study of a prospectively collected cohort of 188 consecutive patients following cardiac arrest treated with TH between May 2007 and January 2012. Smoking status was retrospectively collected via chart review and was classified as “ever” or “never”. Primary endpoint was survival to hospital discharge with a good neurologic outcome and was compared between smokers and nonsmokers. Logistic regression analysis was used to assess the association between smoking status and neurologic outcome at hospital discharge; adjusting for age, initial rhythm, time to return of spontaneous circulation (ROSC), bystander CPR, and time to initiation of TH.

Results

Smokers were significantly more likely to survive to hospital discharge with good neurologic outcome compared to nonsmokers (50% vs. 28%, p = 0.003). After adjusting for age, initial rhythm, time to ROSC, bystander CPR, and time to initiation of TH, a history of smoking was associated with increased odds of survival to hospital discharge with good neurologic outcome (OR 3.54, 95% CI 1.41–8.84, p = 0.007).

Conclusions

Smoking is associated with improved survival with good neurologic outcome in patients following cardiac arrest. We hypothesize that our findings reflect global ischemic conditioning caused by smoking.     

Correlation between initial serum levels of lactate after return of spontaneous circulation and survival and neurological outcomes in patients who undergo therapeutic hypothermia after cardiac arrest

ObjectivesWe analysed the relationship between serum levels of lactate within 1 h of return of spontaneous circulation (ROSC) and survival and neurological outcomes in patients who underwent therapeutic hypothermia (TH).MethodsThis was a multi-centre retrospective and observational study that examined data from the first Korean Hypothermia Network (KORHN) registry from 2007 to 2012. The inclusion criteria were out-of-hospital cardiac arrest (OHCA) and examination of serum levels of lactate within 1 h after ROSC, taken from KORHN registry data. The primary endpoint was survival outcome at hospital discharge, and the secondary endpoint was poor neurological outcome (Cerebral Performance Category, CPC, 3–5) at hospital discharge. Initial lactate levels and other variables collected within 1 h of ROSC were analysed via multivariable logistic regression.ResultsData from 930 cardiac arrest patients who underwent TH were collected from the KORHN registry. In a total of 443 patients, serum levels of lactate were examined within 1 h of ROSC. In-hospital mortality was 289/443 (65.24%), and 347/443 (78.33%) of the patients had CPCs of 3–5 upon hospital discharge. The odds ratios of lactate levels for CPC and in-hospital mortality were 1.072 (95% confidence interval (CI) 1.026–1.121) and 1.087 (95% CI = 1.031–1.147), respectively, based on multivariate ordinal logistic regression analyses.ConclusionHigh levels of lactate in serum measured within 1 h of ROSC are associated with hospital mortality and high CPC scores in cardiac arrest patients treated with TH.     

Therapeutic hypothermia following cardiac arrest: a review of the evidence

Aims and objectives: This paper aims to undertake a review on the current evidence available on therapeutic hypothermia (TH) following cardiac arrest. Background: The use of TH has been associated as a potential treatment for a number of medical conditions including head injury and cerebral vascular accidents. Within the past decade, there have been numerous studies focusing upon the use of hypothermia following cardiac arrest. This paper evaluates the research on the use of TH following cardiac arrest and provides recommendations for clinical practice. Evidence from randomized controlled trials that are reviewed in this paper found that neurological outcome and mortality were significantly improved following inducing hypothermia following cardiac arrest. Search strategies: The following databases were accessed: Bandolier, Embase, Medline, Science Direct, CINAHL, Blackwell Synergy, Nursing Collection, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews and the National Electronic Library for Health. The following key words were used to search the databases: ‘Therapeutic hypothermia’, ‘Induced hypothermia’, ‘cooling post cardiac arrest’ and ‘post cardiac arrest care’. Inclusion and exclusion criteria: Only evidences published within the past 10 years and written in English were included. Studies on TH for the treatment of raised intracranial pressure were excluded. Conclusions: All adult patients who have return of spontaneous circulation and remain unconscious following cardiac arrest should be considered for TH between 32°C and 34°C for at least 12–24 h as this will improve patient mortality and morbidity. Acute hospitals need to devise policies and guidelines on the use of TH following cardiac arrest that include methods on how to achieve effective cooling by cold i.v. infusions, ice packs or purchasing specific cooling mattresses.     

Postresuscitation hemodynamics during therapeutic hypothermia after out-of-hospital cardiac arrest with ventricular fibrillation: A retrospective study

Aims of the study

To evaluate the incidence of postresuscitation myocardial depression (PRMD) and hemodynamical parameters associated with PRMD in patients treated with therapeutic hypothermia (TH) after out-of-hospital cardiac arrest with ventricular fibrillation (OHCA-VF).

Methods

Analysis of hemodynamical data from computerized clinical databases of two academic ICUs during two year period. We analyzed hemodynamical data from a subgroup of patients with pulmonary artery catheter (PAC). We defined PRMD as a cardiac index (CI) less than 1.5 l/(min m²) any time during the first 12 h and compared clinical variables and hemodynamical parameters in patients with or without PRMD.

Results

Of 120 included patients PAC monitoring was used in 47 (39%). Of 47, 31 (66%, 95% CI 52% to 80%) developed PRMD. There was no difference in urinary output, lactate, mean arterial or central venous pressures or mixed venous saturation between patients with or without PRMD. Low CI was reversed with dobutamine infusion. Presence or absence PRMD was not associated with 6-month neurological outcome.

Conclusion

Two-thirds of the OHCA-VF patients develops transient postresuscitation myocardial depression not easily detected without monitoring of CI during therapeutic hypothermia. Further controlled studies are warranted to evaluate the value of different hemodynamic targets and monitoring after cardiac arrest in terms of outcome.     

Pyrexia and neurologic outcomes after therapeutic hypothermia for cardiac arrest

Objective

Therapeutic hypothermia, also known as targeted temperature management (TTM), improves clinical outcomes in patients resuscitated from cardiac arrest. Hyperthermia after discontinuation of active temperature management (“rebound pyrexia”) has been observed, but its incidence and association with clinical outcomes is poorly described. We hypothesized that rebound pyrexia is common after rewarming in post-arrest patients and is associated with poor neurologic outcomes.

Methods

Retrospective multicenter US clinical registry study of post-cardiac arrest patients treated with TTM at 11 hospitals between 5/2005 and 10/2011. We assessed the incidence of rebound pyrexia (defined as temperature >38 °C) in post-arrest patients treated with TTM and subsequent clinical outcomes of survival to discharge and “good” neurologic outcome at discharge, defined as cerebral performance category (CPC) 1–2.

Results

In this cohort of 236 post-arrest patients treated with TTM, mean age was 58.1 ± 15.7 y and 106/236 (45%) were female. Of patients who survived at least 24 h after TTM discontinuation (n = 167), post-rewarming pyrexia occurred in 69/167 (41%), with a median maximum temperature of 38.7 (IQR 38.3–38.9). There were no significant differences between patients experiencing any pyrexia and those without pyrexia regarding either survival to discharge (37/69 (54%) v 51/98 (52%), p = 0.88) or good neurologic outcomes (26/37 (70%) v 42/51 (82%), p = 0.21). We compared patients with marked pyrexia (greater than the median pyrexia of 38.7 °C) versus those who experienced no pyrexia or milder pyrexia (below the median) and found that survival to discharge was not statistically significant (40% v 56% p = 0.16). However, marked pyrexia was associated with a significantly lower proportion of CPC 1–2 survivors (58% v 80% p = 0.04).

Conclusions

Rebound pyrexia occurred in 41% of TTM-treated post-arrest patients, and was not associated with lower survival to discharge or worsened neurologic outcomes. However, among patients with pyrexia, higher maximum temperature (>38.7 °C) was associated with worse neurologic outcomes among survivors to hospital discharge.     

Neurologic outcome in comatose patients resuscitated from out-of-hospital cardiac arrest with prolonged downtime and treated with therapeutic hypothermia

Background

Previous reports have shown that prolonged duration of resuscitation efforts in out-of-hospital cardiac arrest (OHCA) is associated with poor neurologic outcome. This concept has recently been questioned with advancements in post-cardiac arrest care including the use of therapeutic hypothermia (TH). The aim of this study was to determine the rate of good neurologic outcome based on the duration of resuscitation efforts in OHCA patients treated with TH.

Methods

This prospective, observational, study was conducted between January 2008 and September 2012. Inclusion criteria consisted of adult non-traumatic OHCA patients who were comatose after return of spontaneous circulation (ROSC) and received TH. The primary endpoint was good neurologic outcome defined as a cerebral performance category score of 1 or 2. Downtime was calculated as the length of time between the patient being recognized as pulseless and ROSC.

Results

105 patients were treated with TH and 19 were excluded due to unknown downtime, leaving 86 patients for analysis. The median downtime was 18.5 (10.0–32.3) min and 33 patients (38.0%) had a good neurologic outcome. When downtime was divided into four groups (≤10 min, 11–20 min, 21–30 min, >30 min), good neurologic outcomes were 62.5%, 37%, 25%, and 21.7%, respectively (p = 0.02). However, even with downtime >20 min, 22.9% had a good neurologic outcome, and this percentage increased to 37.5% in patients with an initial shockable rhythm.

Conclusions

Although longer downtime is associated with worse outcome in OHCA patients, we found that comatose patients who have been successfully resuscitated and treated with TH have neurologically intact survival rates of 23% even with downtime >20 min.     

Amplitude-integrated EEG (aEEG) predicts outcome after cardiac arrest and induced hypothermia

Objective To evaluate the use of continuous amplitude-integrated EEG (aEEG) as a prognostic tool for survival and neurological outcome in cardiac arrest patients treated with hypothermia.Design Prospective, observational study.Setting Multidisciplinary intensive care unit in a university hospital.Intervention Comatose survivors of cardiac arrest were treated with induced hypothermia for 24 h. An aEEG recording was initiated upon arrival at the ICU and continued until the patient regained consciousness or, if the patient remained in coma, no longer than 120 h. The aEEG recording was not available to the ICU physician, and the aEEG tracings were interpreted by a neurophysiologist with no knowledge of the patient's clinical status. Only clinically visible seizures were treated. Measurements and results Thirty-four consecutive hypothermia-treated cardiac arrest survivors were included. At normothermia (mean 37 h after cardiac arrest), the aEEG pattern was discriminative for outcome. All 20 patients with a continuous aEEG at this time regained consciousness, whereas 14 patients with pathological aEEG patterns (flat, suppression-burst or status epilepticus) did not regain consciousness and died in hospital. Patients were evaluated neurologically upon discharge from the ICU and after 6 months, using the Cerebral Performance Category (CPC) scale. Eighteen patients were alive with a good cerebral outcome (CPC 1--2) at 6-month follow-up. Conclusion A continuous aEEG pattern at the time of normothermia was discriminative for regaining consciousness. aEEG is an easily applied method in the ICU setting.     

Cold infusions alone are effective for induction of therapeutic hypothermia but do not keep patients cool after cardiac arrest

AIM OF THE STUDY: Cold infusions have proved to be effective for induction of therapeutic hypothermia after cardiac arrest but so far have not been used for hypothermia maintenance. This study investigates if hypothermia can be induced and maintained by repetitive infusions of cold fluids and muscle relaxants. MATERIAL AND METHODS: Patients were eligible, if they had a cardiac arrest of presumed cardiac origin and no clinical signs of pulmonary oedema or severely reduced left ventricular function. Rocuronium (0.5 mg/kg bolus, 0.5 mg/kg/h for maintenance) and crystalloids (30 ml/kg/30 min for induction, 10 ml/kg every 6h for 24h maintenance) were administered via large bore peripheral venous cannulae. If patients failed to reach 33+/-1 degrees C bladder temperature within 60 min, endovascular cooling was applied. RESULTS: Twenty patients with a mean age of 57 (+/-15) years and mean body mass index of 27 (+/-4)kg/m(2) were included (14 males). Mean temperature at initiation of cooling (median 27 (IQR 16; 87)min after admission) was 35.4 (+/-0.9) degrees C. In 13 patients (65%) the target temperature was reached within 60 min, 7 patients (35%) failed to reach the target temperature. Maintaining the target temperature was possible in three (15%) patients and no adverse events were observed. CONCLUSION: Cold infusions are effective for induction of hypothermia after cardiac arrest, but for maintenance additional cooling techniques are necessary in most cases.     

Serotonin syndrome after therapeutic hypothermia for cardiac arrest: A case series

Aim

To describe causes, manifestations, and diagnosis of serotonin syndrome following therapeutic hypothermia (TH) after cardiac arrest.

Methods

Retrospective case series from a tertiary academic medical center.

Results

Three male patients suffered witnessed out-of-hospital cardiac arrests and were treated with induced TH. Initial cardiac rhythms included asystole in two and ventricular fibrillation in one. Following completion of rewarming, all three developed neurological signs unexpected for their clinical condition. These included rigidity, hyperreflexia, diffuse tremors, ankle clonus, and marked agitated delirium. Patients also were febrile, hypertensive, and tachycardic. A diagnosis of serotonin syndrome was made in all cases and serotonergic medications were discontinued. All three patients recovered consciousness and two made a full neurological recovery. One patient remained dependent on others for activities of daily living at the time of hospital discharge because of short-term memory impairment.

Conclusions

Unexpected neurologic findings and prolonged high fever following recovery from TH can be manifestations of serotonin syndrome rather than post-cardiac arrest anoxic brain injury.     

Neurologic recovery after therapeutic hypothermia in patients with post-cardiac arrest myoclonus

Early myoclonus in comatose survivors of cardiac arrest, even when it is not myoclonic status epilepticus (MSE), is considered a sign of severe global brain ischemia and has been associated with high rates of mortality and poor neurologic outcomes. We report on three survivors of primary circulatory cardiac arrests who had good neurologic outcomes (two patients with a CPC score = 1 and one patient with a CPC score = 2) after mild therapeutic hypothermia, despite exhibiting massive myoclonus within the first 4 h after return of spontaneous circulation. The concept that early myoclonus heralds a uniformly poor prognosis may need to be reconsidered in the era of post-cardiac arrest mild therapeutic hypothermia.     

Health-related quality of life improves during the first six months after cardiac arrest and hypothermia treatment

Aim of the study

To investigate whether there were any changes in and correlations between anxiety, depression and health-related quality of life (HRQoL) over time, between hospital discharge and one and six months after cardiac arrest (CA), in patients treated with therapeutic hypothermia (TH).

Method

During a 4-year period at three hospitals in Sweden, 26 patients were prospectively included after CA treated with TH. All patients completed the questionnaires Hospital Anxiety and Depression Scale (HADS), Euroqol (EQ5D), Euroqol visual analogue scale (EQ-VAS) and Short Form 12 (SF12) at three occasions, at hospital discharge, and at one and 6 months after CA.

Result

There was improvement over time in HRQoL, the EQ5D index (p = 0.002) and the SF12 physical component score (PCS) (p = 0.005). Changes over time in anxiety and depression were not found. Seventy-three percent of patients had an EQ-VAS score below 70 (scale 0–100) on overall health status at discharge from hospital; at 6 months the corresponding figure was 41%. Physical problems were the most common complaint affecting HRQoL. A correlation was found between depression and HRQoL, and this was strongest at six months (rs = −0.44 to −0.71, p ≤ 0.001).

Conclusion

HRQoL improves over the first 6 months after a CA. Patients reported lower levels of HRQoL on the physical as compared to mental component. The results indicate that the less anxiety and depression patients perceive, the better HRQoL they have and that time can be an important factor in recovery after CA.     

Outcomes of asphyxial cardiac arrest patients who were treated with therapeutic hypothermia: A multicentre retrospective cohort study

IntroductionWhile therapeutic hypothermia (TH) is in clinical use, its efficacy in certain patient groups is unclear. This study was designed to describe the characteristics and outcomes of patients with out-of-hospital cardiac-arrest (OHCA) caused by asphyxia, who were treated with TH.Patients and methodsA multicentre, retrospective, registry-based study was performed using data from the period 2007–2012. Comatose patients who were treated with TH after asphyxial cardiac arrest were included, while those who with cardiac arrest attributed to hanging, drowning or gas intoxication were excluded.ResultsOf a total of 932 OHCA patients in the registry, 111 were enrolled in this study. The mean age was 65.8 ± 16.3 years with individuals who were ≥65 years of age accounted for 61.3% of the cohort. Foreign-body airway obstruction was the most common cause (70.3%) of the cardiac arrest. Eighty patients (72.1%) presented with an initial non-shockable rhythm. In all institutions target TH temperatures were 32–34 °C, but TH maintenance times varied. A total of 52 patients (46.8%) survived, of whom six patients (5.4%) showed a good neurologic outcome (cerebral performance category scale 1–2). The pupil light reflex, corneal reflex and time to return of spontaneous circulation (p = 0.012, 0.015 and 0.032, respectively) were associated with survival. Witnessed arrest, age, previous lung disease, bystander basic life support and time factors were not associated with survival.ConclusionAbout half of patients who underwent TH after asphyxial cardiac arrest survived, but a very small number showed a good neurologic outcome. The TH maintenance times were not uniform in these patients. Additional research regarding both the appropriate TH guidelines for patients with asphyxial cardiac arrest and improvement of their neurologic outcome is needed.     

Use of ice-cold crystalloid for inducing mild therapeutic hypothermia following out-of-hospital cardiac arrest

Objective

Out of hospital cardiac arrest (OHCA) results in a significant mortality and neurological disability in survivors. The application of mild therapeutic hypothermia (MTH) to patients who have suffered an OHCA with a ventricular rhythm results in a significant reduction in mortality and neurological disability in survivors. The optimal timing of this intervention has not been clearly established; however there is emerging evidence to suggest that maximal benefit is gained from initiation at the earliest time point. Despite this, recent surveys have shown a considerable delay in initiating MTH, with variable uptake in emergency departments (EDs), where a number of impediments to delivery have been identified.

Method

We have reviewed the literature to determine what are the barriers to the initiation of MTH in the ED. We also reviewed the literature on the use of ice-cold crystalloids as a practical, simple, effective, and safe method to induce MTH.

Results

Among the several reasons, the perception of a lack of a practical method and logistical constraints are cited as common barriers. However, the available literature on the use of ice-cold crystalloids suggests that this is a safe and effective method of inducing MTH.

Conclusion

ED staff need to be aware that the use of ice-cold fluids is an inexpensive, readily available and easy to perform method of inducing MTH in patients who suffer an out-of hospital cardiac arrest with a ventricular rhythm. We therefore suggest that ice-cold crystalloid is routinely stocked in emergency departments and, unless contraindicated, is used to induce MTH. Optimal post-resuscitation care also includes timely treatment of the cause of the OHCA and maintenance of MTH. Staff education and care bundles may help to facilitate optimal inter-departmental management of the patient.     

Predictors of adopting therapeutic hypothermia for post-cardiac arrest patients among Canadian emergency and critical care physicians

Therapeutic hypothermia improves outcomes in resuscitated cardiac arrest patients, but prior application rates are less than 30%. We sought to evaluate self-reported physician adoption, predictors of adoption, and barriers to use among Canadian emergency and critical care physicians.A web-based modified Dillman questionnaire asked all physicians on the membership lists of the Canadian Association of Emergency Physicians and the Canadian Critical Care Forum physicians to report their experience with therapeutic hypothermia using the Pathman framework of changing physician behaviour. We used logistic regression to explore the association between physician and practice variables and the adoption of therapeutic hypothermia.We surveyed 1264 physicians; 39% responded. Most (78%) were emergency physicians, 54% worked at tertiary care hospitals, 62% treated >10 arrests annually and 50% had standardized cooling protocols. Most respondents were aware of therapeutic hypothermia (99%) and agreed that it is beneficial (91%), but only two-thirds (68%) had used it in clinical practice. Predictors for adopting therapeutic hypothermia included critical care field of practice (OR 6.3, 95% CI 2.5-16.0), availability of a cooling protocol (OR 5.6, CI 3.1-10.0), being <10 years post-residency (OR 2.0, CI 1.2-3.3), and treating >10 cardiac arrests annually (OR 2.6, CI 1.6-4.1). Common barriers included: lack of awareness of recommended practice (31%), perceptions of poor prognosis (25%), too much work required to cool (20%) and staffing shortages (20%).Therapeutic hypothermia after cardiac arrest has not been universally adopted. Adoption might be improved through protocol implementation, education about benefits and prognosis, and strategies to make administration easier.     

Serum matrix metalloproteinases in patients resuscitated from cardiac arrest. The association with therapeutic hypothermia

Aim

To study the systemic levels of matrix metalloproteinases (MMP) -7, -8 and -9 and their inhibitor TIMP-1 in cardiac arrest patients and the association with mild therapeutic hypothermia treatment on the serum concentration of these enzymes.

Methods

MMP-7, -8 and -9 and tissue inhibitor of metalloproteinases-1 (TIMP-1) were analysed in blood samples obtained from 51 patients resuscitated from cardiac arrest. The samples were taken at 24 and 48 h from restoration of spontaneous circulation (ROSC). The biomarker levels were compared between patients (N = 51) and healthy controls (N = 10) and between patients who did (N = 30) and patients who did not (N = 21) receive mild therapeutic hypothermia.

Results

MMP-7 (median 0.47 ng/ml), MMP-8 (median 31.16 ng/ml) and MMP-9 (median 253.00 ng/ml) levels were elevated and TIMP-1 levels suppressed (median 78.50 ng/ml) in cardiac arrest patients as compared with healthy controls at 24 h from ROSC. Hypothermia treatment associated with attenuated elevation of MMP-9 (p = 0.001) but not MMP-8 (p = 0.02) or MMP-7 (p = 0.69). Concentrations of MMPs -7, -8 and -9 correlated with the leukocyte count but not with C-reactive protein (CRP) or neurone-specific enolase (NSE) levels.

Conclusion

We demonstrated that the systemic levels of MMP-7, -8 and -9 but not TIMP-1 are elevated in cardiac arrest patients in the 48 h post-resuscitation period relative to the healthy controls. Patients who received therapeutic hypothermia had lower MMP-9 levels compared to non-hypothermia treated patients, which generates hypothesis about attenuation of inflammatory response by hypothermia treatment.     

Cold saline infusion and ice packs alone are effective in inducing and maintaining therapeutic hypothermia after cardiac arrest

Aim of the study

Hypothermia treatment with cold intravenous infusion and ice packs after cardiac arrest has been described and used in clinical practice. We hypothesised that with this method a target temperature of 32-34 °C could be achieved and maintained during treatment and that rewarming could be controlled.

Materials and methods

Thirty-eight patients treated with hypothermia after cardiac arrest were included in this prospective observational study. The patients were cooled with 4 °C intravenous saline infusion combined with ice packs applied in the groins, axillae, and along the neck. Hypothermia treatment was maintained for 26 h after cardiac arrest. It was estimated that passive rewarming would occur over a period of 8 h. Body temperature was monitored continuously and recorded every 15 min up to 44 h after cardiac arrest.

Results

All patients reached the target temperature interval of 32-34 °C within 279 ± 185 min from cardiac arrest and 216 ± 177 min from induction of cooling. In nine patients the temperature dropped to below 32 °C during a period of 15 min up to 2.5 h, with the lowest (nadir) temperature of 31.3 °C in one of the patients. The target temperature was maintained by periodically applying ice packs on the patients. Passive rewarming started 26 h after cardiac arrest and continued for 8 ± 3 h. Rebound hyperthermia (>38 °C) occurred in eight patients 44 h after cardiac arrest.

Conclusions

Intravenous cold saline infusion combined with ice packs is effective in inducing and maintaining therapeutic hypothermia, with good temperature control even during rewarming.     

NSE and S-100B are not sufficiently predictive of neurologic outcome after therapeutic hypothermia for cardiac arrest

Introduction

Prognostication of cardiac arrest survivors is challenging since therapeutic hypothermia (TH) has been introduced. We evaluated serum biomarkers and motor response.

Methods

This was a retrospective data analysis including patients in the years 2007–2012. Blood was drawn and a neurological examination was performed on admission and every morning. Outcomes were evaluated 6 months after discharge and dichotomized into good (cerebral performance category (CPC) = 1 or 2) and poor (CPC = 3, 4 or 5).

Results

123 patients (79.7% male, 63 ± 14 years) received TH; 50% had a good outcome. On admission, S-100B (P = 0.004) was significantly associated with the outcome, as well as neuron-specific enolase (NSE; P = 0.020) and S-100B (P = 0.004) on day 1 after admission. NSE on day 2, NSE progression from day 1 to 2 and motor response on day 3 also predicted the outcome (all P < 0.001).NSE > 33 μg l⁻¹ only predicted a poor outcome with a specificity of 76%. An absent motor response on day 3 was the most sensitive marker (94%). NSE > 41.1 μg l⁻¹ combined with S-100B > 0.461 μg l⁻¹ on day 1 was the most specific marker (96%).

Conclusion

Although NSE and S-100B levels are associated with the outcome, the use of previously described cut-off values was insufficiently predictive of neurologic outcome. Caution should be exercised in the use of these tests to provide neuroprognostication.     

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 °C (95% CI 33.2-34.5). All patients arriving in the ED post OHCA had a relatively low esophageal temperature (34.3 °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 °C vs 34.3 °C, p < 0.05). Patients surviving to hospital discharge also took longer to reach T_targ than non-survivors (2 h 48 min vs 1 h 32 min, 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.