Moritz Haugk

Mild therapeutic hypothermia is associated with favourable outcome in patients after cardiac arrest with non-shockable rhythms

AIM Mild therapeutic hypothermia (32-34°C) improves neurological recovery and reduces the risk of death in comatose survivors of cardiac arrest when the initial rhythm is ventricular fibrillation or pulseless ventricular tachycardia. The aim of the presented study was to investigate the effect of mild therapeutic hypothermia (32-34°C for 24h) on neurological outcome and mortality in patients who had been successfully resuscitated from non-ventricular fibrillation cardiac arrest. METHODS In this retrospective cohort study we included cardiac arrest survivors of 18 years of age or older suffering a witnessed out-of-hospital cardiac arrest with asystole or pulseless electric activity as the first documented rhythm. Data were collected from 1992 to 2009. Main outcome measures were neurological outcome within six month and mortality after six months. RESULTS Three hundred and seventy-four patients were analysed. Hypothermia was induced in 135 patients. Patients who were treated with mild therapeutic hypothermia were more likely to have good neurological outcomes in comparison to patients who were not treated with hypothermia with an odds ratio of 1.84 (95% confidence interval: 1.08-3.13). In addition, the rate of mortality was significantly lower in the hypothermia group (odds ratio: 0.56; 95% confidence interval: 0.34-0.93). CONCLUSION Treatment with mild therapeutic hypothermia at a temperature of 32-34°C for 24h is associated with improved neurological outcome and a reduced risk of death following out-of-hospital cardiac arrest with non-shockable rhythms.

Relationship between time to target temperature and outcome in patients treated with therapeutic hypothermia after cardiac arrest

IntroductionOur purpose was to study whether the time to target temperature correlates with neurologic outcome in patients after cardiac arrest with restoration of spontaneous circulation treated with therapeutic mild hypothermia in an academic emergency department.MethodsTemperature data between April 1995 and June 2008 were collected from 588 patients and analyzed in a retrospective cohort study by observers blinded to outcome. The time needed to achieve an esophageal temperature of less than 34°C was recorded. Survival and neurological outcomes were determined within six months after cardiac arrest.ResultsThe median time from restoration of spontaneous circulation to reaching a temperature of less than 34°C was 209 minutes (interquartile range [IQR]: 130-302) in patients with favorable neurological outcomes compared to 158 min (IQR: 101-230) (P < 0.01) in patients with unfavorable neurological outcomes. The adjusted odds ratio for a favorable neurological outcome with a longer time to target temperature was 1.86 (95% CI 1.03 to 3.38, P = 0.04).ConclusionsIn comatose cardiac arrest patients treated with therapeutic hypothermia after return of spontaneous circulation, a faster decline in body temperature to the 34°C target appears to predict an unfavorable neurologic outcome.

Non-invasive continuous cerebral temperature monitoring in patients treated with mild therapeutic hypothermia: an observational pilot study.

AIM OF THE STUDY To investigate if body temperature as measured with a prototype of a non-invasive continuous cerebral temperature sensor using the zero-heat-flow method to reflect the oesophageal temperature (core temperature) during mild therapeutic hypothermia after cardiac arrest. METHODS In patients over 18 years old with restoration of spontaneous circulation after cardiac arrest, a temperature sensor that uses the zero-heat-flow principle was placed on the forehead during the periods of cooling and re-warming. This temperature was compared to oesophageal temperature as the primary temperature-monitoring site. To assess agreement, we used the Bland-Altman approach and Lins concordance correlation coefficient. RESULTS From September 2008 to April 2009, data from 19 patients were analysed. The median time from restoration of spontaneous circulation until temperature sensor application was 53min (interquartile range, 31; 96). All sensors were removed when a core temperature of 36 degrees C was reached. These measurements were in agreement with oesophageal temperature measurements. No allergic reaction, rash or other irritation occurred on the skin around or under the probes. Bland-Altman results showed a bias of -0.12 degrees C and 95% limits of agreement of -0.59 and +0.36 degrees C. Lins concordance correlation coefficient was 0.98. CONCLUSIONS Body temperature measurements using a non-invasive continuous cerebral temperature sensor prototype that uses the zero-heat-flow method accurately reflected oesophageal temperature measurements during mild therapeutic hypothermia in patients with restoration of spontaneous circulation after cardiac arrest.

Quality of closed chest compression on a manikin in ambulance vehicles and flying helicopters with a real time automated feedback

CONTEXT Automated verbal and visual feedback improves quality of resuscitation in out-of-hospital cardiac arrest and was proven to increase short-term survival. Quality of resuscitation may be hampered in more difficult situations like emergency transportation. Currently there is no evidence if feedback devices can improve resuscitation quality during different modes of transportation. OBJECTIVE To assess the effect of real time automated feedback on the quality of resuscitation in an emergency transportation setting. DESIGN Randomised cross-over trial. SETTING Medical University of Vienna, Vienna Municipal Ambulance Service and Helicopter Emergency Medical Service Unit (Christophorus Flugrettungsverein) in September 2007. PARTICIPANTS European Resuscitation Council (ERC) certified health care professionals performing CPR in a flying helicopter and in a moving ambulance vehicle on a manikin with human-like chest properties. INTERVENTIONS CPR sessions, with real time automated feedback as the intervention and standard CPR without feedback as control. MAIN OUTCOME MEASURES Quality of chest compression during resuscitation. RESULTS Feedback resulted in less deviation from ideal compression rate 100 min(-1) (9+/-9 min(-1), p<0.0001) with this effect becoming steadily larger over time. Applied work was less in the feedback group compared to controls (373+/-448 cm x compression; p<0.001). Feedback did not influence ideal compression depth significantly. There was some indication of a learning effect of the feedback device. CONCLUSIONS Real time automated feedback improves certain aspects of CPR quality in flying helicopters and moving ambulance vehicles. The effect of feedback guidance was most pronounced for chest compression rate.

Surface Cooling for Rapid Induction of Mild Hypothermia After Cardiac Arrest: Design Determines Efficacy

OBJECTIVES Recently, a novel cooling pad was developed for rapid induction of mild hypothermia after cardiac arrest. The aim of this study was to evaluate the cooling efficacy of three different pad designs for in-hospital cooling. METHODS Included in this prospective interventional study were patients with esophageal temperature (Tes) > 34 degrees C on admission. The cooling pad consists of multiple cooling units, filled with a combination of graphite and water, which is precooled to -18 degrees C (design A) or to -9 degrees C (designs B and C) before use. The designs of the cooling pad differed in number, shape, and thickness of the cooling units, with weights of 9.7 kg (design A), 5.3 kg (design B), and 6.2 kg (design C). All three designs were tested in sequential order and were changed according to the results found in the previous trial. Cooling was started after admission until Tes = 34 degrees C, when the cooling pad was removed. The target temperature of Tes = 32-34 degrees C was maintained for 24 hours. Data are presented as medians and interquartile ranges (IQRs = 25%-75%) or proportions. RESULTS Cooling rates were 3.4 degrees C/hour (IQR = 2.5-3.7) with design A (n = 12), 2.8 degrees C/hour (IQR = 1.6-3.3) with design B (n = 7), and 2.9 degrees C/hour (IQR = 1.9-3.6) with design C (n = 10; p = 0.5). To reach 34 degrees C, the cooling pad had to be exchanged with a new one due to melting and therefore depleting cooling capacity in three patients with design A, in five patients with design B, and in no patient with design C (p = 0.004). CONCLUSIONS With adequate design and storage temperature, the cooling pad proved to be efficient for rapid in-hospital cooling of patients resuscitated from cardiac arrest.

Cardiac arrest survivors with moderate elevated body mass index may have a better neurological outcome: A cohort study

AIM Body mass index (BMI) may influence the quality of cardiopulmonary resuscitation and may influence prognosis after cardiac arrest. To review the direct effect of obesity on outcome after cardiac arrest, the following cohort study was conducted. METHODS This study based on a cardiac arrest registry comprising all adult patients with cardiac arrest of non-traumatic origin and restoration of spontaneous circulation (ROSC) admitted to the department of emergency medicine of a tertiary-care facility. Data were collected between January 1992 and December 2007 according to the Utstein criteria. We assessed the association between BMI according to the WHO classification (underweight, BMI<18.5; normal weight, 18.5-24.9; overweight, 25.0-29.9; obese ≥ 30), six-month survival and neurological recovery. RESULTS Analysis was carried out on a total of 1915 adult patients (32% female). Patients had a median age of 59 years (interquartile range [IQR] 49-70) and a median BMI of 26.0 (IQR 23.9-29.1). Survival to six months was 50%. There was no significant difference in survival between the BMI groups (underweight 46%, normal weight 47%, overweight 52%, obese 51%). In a multivariate analysis neurological outcome was better in overweight patients as compared to subjects with normal BMI (odds ratio 1.35; 95% confidence interval 1.02-1.79). CONCLUSION Body mass index may have no direct influence on six-month survival after cardiac arrest, but patients with moderately elevated BMI may have a better neurological prognosis.

Transport with ongoing cardiopulmonary resuscitation may not be futile

BACKGROUND Despite it being generally regarded as futile, patients are regularly brought to the emergency department with ongoing cardiopulmonary resuscitation (CPR). METHODS Long-term outcome and its predictors in patients who were transported during ongoing CPR were evaluated in an observational study. Adult patients with non-traumatic cardiac arrest admitted to the Department of Emergency Medicine of a tertiary-care facility after transport with ongoing chest compression were retrospectively analysed. Multivariate analysis of epidemiological variables, treatment, blood gas values on admission, cause of arrest, and location of arrest was performed to find factors that were predictive for favourable long-term outcome (6-month survival, best cerebral performance category 1 or 2). RESULTS Over 15 yr (1991-2006), a total of 2643 patients were treated after cardiac arrest. Of these, 327 patients received chest compressions during transport and were analysed (out-of-hospital cardiac arrest: n=244, in-hospital: n=83; the remaining 2316 patients were either stabilized before transport or suffered their arrest in our department). Return of spontaneous circulation was achieved in 31% of patients (n=102). Of these, 19 (19%) had favourable long-term outcome (6% of total). Independent predictors of good outcome were age, witnessed arrest, amount of epinephrine, and initial shockable rhythm. Among the patients with cardiac origin of arrest, 11 out of 197 patients (6%) survived; pulmonary origin, 4 out of 46 patients (9%); hypothermic arrest, 1 of 10 patients (10%); and intoxications, one out of nine patients (11%). CONCLUSIONS Post-resuscitation care in patients who receive CPR during transport is not futile. Once restoration of spontaneous circulation is established, one out of five patients will have good long-term outcome.

Femoro-iliacal artery versus pulmonary artery core temperature measurement during therapeutic hypothermia: An observational study

AIM OF THE STUDY Therapeutic hypothermia after cardiac arrest improves neurologic outcome. The temperature measured in the pulmonary artery is considered to best reflect core temperature, yet is limited by invasiveness. Recently a femoro-arterial thermodilution catheter (PiCCO-Pulse Contour Cardiac Output) has been introduced in clinical practice as a safe and accurate haemodynamic monitoring system, which is also able to measure blood temperature. The aim of the study was to investigate, if the temperature measured with the PiCCO catheter reflects pulmonary artery temperature better than other sites during therapeutic hypothermia. METHODS In this observational study twenty patients after cardiac arrest and successful resuscitation were cooled with various cooling methods to 33 ± 1°C for 24h, followed by rewarming. Temperatures were recorded continuously in the pulmonary artery (Tpa), femoro-iliacal artery (Tpicco), ear canal (Tear), oesophagus (Toeso) and urinary bladder (Tbla). We assessed agreement of methods using the Bland Altman approach including bias and limits of agreement (LA). RESULTS All other sites differed significantly from Tpa with the bias varying from 0.4°C (Tbla) to -0.6°C (Tear). Standard deviations varied from 0.1°C (Tpicco, Toeso) to 0.5°C (Tear). For all sites bias was closer to zero with increasing average temperatures. Bias tended to be larger in the cooling phase compared to overall measurements. CONCLUSIONS Temperature measurement in the femoro-iliacal artery (Tpicco) reflects the gold standard of pulmonary artery temperature most accurately, especially during the cooling phase. Tpicco is easily accessible and might be used for monitoring core temperature without the need for additional temperature probes.

Temperature monitored on the cuff surface of an endotracheal tube reflects body temperature

Objective:When treating patients with cardiac arrest with mild therapeutic hypothermia, a reliable and easy-to-use temperature probe is desirable. This study was conducted to investigate the accuracy and safety of tracheal temperature as a measurement of body temperature. Design:Observational cohort study. Setting:Emergency department of a tertiary care university hospital. Patients:Patients successfully resuscitated from cardiac arrest intended for mild hypothermia therapy. Interventions:Intubation was performed with a newly developed endotracheal tube that contains a temperature sensor inside the cuff surface. During the cooling, mild hypothermia maintenance, and rewarming phases, the temperature was recorded minute by minute. These data were compared with the temperature assessed by esophageal and blood temperature probes. Thereafter, tracheoscopy was performed to evaluate the condition of the tracheal mucosa. Measurements and Main Results:Approximately 2000 measurements per temperature sensor per patient were recorded in 21 patients. The mean bias between the blood temperature and the tracheal temperature was −0.16°C (limits of agreement: −0.36°C to 0.04°C). The mean bias between the esophageal and tracheal temperatures was −0.22°C (limits of agreement: −0.49°C to 0.07°C). Agreement between temperature probes investigated by the Bland-Altman method showed a mean bias of less than −¼°C, and time lags assessed graphically by hysteresis plots were negligible. No clinically relevant injury to the tracheal mucosa was detected. Conclusion:Temperature monitoring at the cuff surface of an endotracheal tube is safe and provides accurate and reliable data in all phases of therapeutically induced mild hypothermia after cardiac arrest.

Prehospital surface cooling is safe and can reduce time to target temperature after cardiac arrest

PURPOSE Mild therapeutic hypothermia proved to be beneficial when induced after cardiac arrest in humans. Prehospital cooling with i.v. fluids was associated with adverse side effects. Our primary objective was to compare time to target temperature of out-of hospital cardiac arrest patients cooled non-invasively either in the prehospital setting vs. the in-hospital (IH) setting, to assess surface-cooling safety profile and long term outcome. METHODS In this retrospective, single center cohort study, a group of adult patients with restoration of spontaneous circulation (ROSC) after out-of hospital cardiac arrest were cooled with a surface cooling pad beginning either in the prehospital or IH setting for 24h. Time to target temperature (33.9°C), temperature on admission, time to admission after ROSC and outcome were compared. Also, rearrests and pulmonary edema were assessed. Neurologic outcome at 12 months was evaluated (Cerebral Performance Category, CPC 1-2, favorable outcome). RESULTS Between September 2005 and February 2010, 56 prehospital cooled patients and 54 IH-cooled patients were treated. Target temperature was reached in 85 (66-117)min (prehospital) and in 135 (102-192)min (IH) after ROSC (p<0.001). After prehospital cooling, hospital admission temperature was 35.2 (34.2-35.8)°C, and in the IH-cooling patients initial temperature was 35.8 (35.2-36.3)°C (p=0.001). No difference in numbers of rearrests and pulmonary edema between groups was observed. In both groups, no skin lesions were observed. Favorable outcome was reached in 26.8% (prehospital) and in 37.0% (IH) of the patients (p=0.17). CONCLUSIONS Using a non-invasive prehospital surface cooling method after cardiac arrest, target temperature can be reached faster without any major complications than starting cooling IH. The effect of early non-invasive cooling on long-term outcome remains to be determined in larger studies.