Resuscitation highlights in 2013: Part 2

Abstract

This is the second of two editorials that review key papers published in Resuscitation in 2013 and includes the topics of advanced life support, post-resuscitation care, prognostication, and cardiac arrest centres.1. Advanced life support1.1 AirwayThe best airway technique during cardiopulmonary resuscitation (CPR) is yet to be determined, and is likely to depend on patient characteristics, the cause of cardiac arrest, the time point during the resuscitation attempt, and the skills of the rescuer.1Soar J. Which airway for cardiac arrest? Do supraglottic airways devices have a role?.Resuscitation. 2013; 84: 1163-1164Abstract Full Text Full Text PDF PubMed Scopus (7) Google ScholarSupraglottic airway device use during CPR is now commonplace and observational data about use of newer ‘second generation’ devices during CPR are now available. Häske and colleagues observed that the i-gel could be successfully inserted during CPR for OHCA by paramedics and physicians with a high success rate (90%), and enabled continuous chest compression without interruption for ventilation in most cases (74%).2Haske D. Schempf B. Gaier G. Niederberger C. Performance of the i-gel during pre-hospital cardiopulmonary resuscitation.Resuscitation. 2013; 84: 1229-1232Abstract Full Text Full Text PDF PubMed Scopus (35) Google Scholar Similarly the laryngeal tube (LT) was successfully inserted on the first attempt in 46/64 cases (71.9%) and on the second attempt in 13/64 cases (20.3%) by volunteer first responders during CPR for out-of-hospital cardiac arrest (OHCA).3Lankimaki S. Alahuhta S. Kurola J. Feasibility of a laryngeal tube for airway management during cardiac arrest by first responders.Resuscitation. 2013; 84: 446-449Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar Rhys and colleagues reported contamination of rescuers from splashing of gastric contents during CPR with the use of the Laryngeal Mask Airway Supreme (LMAS) in three out of 171 insertions.4Rhys M. Voss S. Benger J. Reference: contamination of ambulance staff using the laryngeal mask airway supreme (LMAS) during cardiac arrest.Resuscitation. 2013; 84: e99Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar The manufacturer responded that the gastric port of the LMAS was performing as intended by protecting the lungs from aspiration of gastric contents, and highlighted the need for personal protective equipment by rescuers during CPR.5Boylan K. Reply to letter: ‘Contamination of ambulance staff using the laryngeal mask airway supreme (LMAS) during cardiac arrest’.Resuscitation. 2013; 84: e101Abstract Full Text Full Text PDF PubMed Scopus (3) Google ScholarMany still believe that despite its relative difficulty, tracheal intubation during CPR remains the ‘gold standard’ airway technique. Kwok and colleagues from Seattle studied this in more detail and reported that those OHCA patients who had a rapid sequence intubation (RSI) attempt with a neuromuscular blocking drug to facilitate tracheal intubation during CPR (15% of 3133 cases) had improved survival to discharge compared with those having an intubation attempt without a neuromuscular blocking drug (82% of cases).6Kwok H. Prekker M. Grabinsky A. Carlbom D. Rea T.D. Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest.Resuscitation. 2013; 84: 1353-1358Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar Those not requiring tracheal intubation (3% of cases) had the best outcomes. Compared with intubation without RSI, the adjusted odds ratios of survival to hospital discharge were 5.6 (95% CI 4.3–7.2) for the RSI group, and 15 (95% CI 9–27) for the no-intubation group. This study suggests an association between patients with intact airway reflexes during CPR, and not requiring tracheal intubation, with an improved outcome after OHCA. This may also explain why some observational studies show that tracheal intubation during CPR is associated with a worse outcome, compared with bag-mask ventilation.Videolaryngoscope technology has the potential to improve successful tracheal intubation whilst minimising harmful interruptions to chest compressions during CPR. Park and colleagues from Korea describe their experience of videolaryngoscope-assisted tracheal intubation during ongoing chest compressions during CPR in the emergency department.7Park S.O. Baek K.J. Hong D.Y. Kim S.C. Lee K.R. Feasibility of the video-laryngoscope (GlideScope®) for endotracheal intubation during uninterrupted chest compressions in actual advanced life support: a clinical observational study in an urban emergency department.Resuscitation. 2013; 84: 1233-1237Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar Success rates (first attempt success overall 66/71 [93%]) and speed of intubation (median 41.5 s) when using the GlideScope® videolaryngoscope were not related to individuals’ experience with standard laryngoscopy.A single-centre US emergency department reported that 1 in 25 emergency tracheal intubations in adult non-cardiac arrest patients over a one-year period were associated with a cardiac arrest.8Heffner A.C. Swords D.S. Neale M.N. Jones A.E. Incidence and factors associated with cardiac arrest complicating emergency airway management.Resuscitation. 2013; 84: 1500-1504Abstract Full Text Full Text PDF PubMed Scopus (104) Google Scholar Cardiac arrest was associated with increased odds of hospital death (OR 14.8; 95% CI 4.2–52). Pre-intubation hypoxaemia and shock were associated with an increased risk of cardiac arrest. By extrapolating from this single centre experience and the estimated 250,000 emergency department tracheal intubations in the US each year, Carlson and Wang estimate 10,000 peri-intubation cardiac arrests annually in the US.9Carlson J.N. Wang H.E. Emergency airway management: can we do better?.Resuscitation. 2013; 84: 1461-1462Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar1.2 Confirmation of tracheal tube position during CPRObservational data from the American Heart Association (AHA) Get With The Guidelines registry (GWTG-R) showed that documentation of tracheal tube position confirmation was associated with increased ROSC and survival to hospital discharge.10Phelan M.P. Ornato J.P. Peberdy M.A. Hustey F.M. American Heart Association's get with the guidelines – resuscitation. I. Appropriate documentation of confirmation of endotracheal tube position and relationship to patient outcome from in-hospital cardiac arrest.Resuscitation. 2013; 84: 31-36Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar Of 176,054 patients in the database, 75,777 had tracheal intubation. There was no documentation of confirmation of tube position in 13,263 (17.5%), auscultation alone in 19,480 (25.7%), and confirmation by capnography or oesophageal detector device in 43,034 (56.8%) cases. Patients with documented tracheal tube position confirmed by capnography or oesophageal detector device had increased ROSC (adjusted OR 1.229 [95% CI 1.179–1.282]) and to survive to hospital discharge (adjusted OR 1.093 [95% CI 1.033–1.157]). Documentation may be a marker of better care, and the importance of confirming correct tracheal intubation during CPR requires greater emphasis during training.11Gwinnutt C. Gwinnutt M. Quality control in CPR: the next step forward?.Resuscitation. 2013; 84: 5-6Abstract Full Text Full Text PDF PubMed Scopus (1) Google ScholarReal time ultrasound during tracheal intubation can identify correct tracheal tube placement in the trachea and show effective inflation of the lungs during ventilation. Chou and colleagues from Taiwan showed that ultrasound of the anterior neck can be used to identify tracheal and oesophageal intubation without the need for interruption in chest compression during CPR.12Chou H.C. Chong K.M. Sim S.S. et al.Real-time tracheal ultrasonography for confirmation of endotracheal tube placement during cardiopulmonary resuscitation.Resuscitation. 2013; 84: 1708-1712Abstract Full Text Full Text PDF PubMed Scopus (75) Google Scholar Ultrasound of the neck, chest and diaphragm may improve accuracy and may enable confirmation of correct tube positioning earlier than end-tidal carbon dioxide (ETCO2) detection.13Blaivas M. Ultrasound, tracheal intubation and cardiopulmonary resuscitation: isn’t there enough to do during a cardiac arrest?.Resuscitation. 2013; 84: 1641-1642Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar Clearly, proficiency in ultrasound and enough helpers during the resuscitation are needed.1.3 Airway management in neonatesFortunately, few neonates require advanced airway interventions. Observational data from five US tertiary neonatal centres showed that only 44% of 455 tracheal intubation attempts (203 patients in the NICU, labour or delivery suites) were successful with ‘attendings’ having the highest success rates (72.2%).14Haubner L.Y. Barry J.S. Johnston L.C. et al.Neonatal intubation performance: room for improvement in tertiary neonatal intensive care units.Resuscitation. 2013; 84: 1359-1364Abstract Full Text Full Text PDF PubMed Scopus (80) Google Scholar The reasons cited for failure were inability to see the vocal cords (25%), patient desaturation and, or bradycardia (41%) and oesophageal intubation (19%). The study did not look at harm. The authors correctly point out safe airway management in neonates needs further study and improvement.Many of the airway techniques used in adults are not always feasible in neonates. For example, in a review of correct tracheal tube placement in newborn infants, Schmölzer and colleagues conclude that chest radiography remains the gold standard.15Schmolzer G.M. O’Reilly M. Davis P.G. Cheung P.Y. Roehr C.C. Confirmation of correct tracheal tube placement in newborn infants.Resuscitation. 2013; 84: 731-737Abstract Full Text Full Text PDF PubMed Scopus (44) Google Scholar They state that exhaled carbon dioxide can give false negative results, and that other monitors require further study. A systematic review and meta-analysis of available clinical trials suggests that the laryngeal mask airway can be used as an alternative to bag-mask ventilation in newborns over 34 weeks gestation and weighing more than 2 kg.16Schmolzer G.M. Agarwal M. Kamlin C.O. Davis P.G. Supraglottic airway devices during neonatal resuscitation: an historical perspective, systematic review and meta-analysis of available clinical trials.Resuscitation. 2013; 84: 722-730Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar1.4 Carbon dioxide, oxygenation, ischaemia and reperfusion during CPRWaveform capnography can be used during CPR to confirm tracheal tube position, measure ventilation rate, and indicate when return of spontaneous circulation (ROSC) occurs. End-tidal carbon dioxide values can potentially help guide the quality of CPR and predict the chances of ROSC and survival. A systematic review of the prognostic value of ETCO2 during CPR identified 23 observational studies that suggest that higher ETCO2 values were associated with an increased likelihood of ROSC.17Touma O. Davies M. The prognostic value of end tidal carbon dioxide during cardiac arrest: a systematic review.Resuscitation. 2013; 84: 1470-1479Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar The risk of bias in observational data, and the lack of blinding to data increasing the risk of a self-fulfilling prophecy, mean that we do not know the ETCO2 value and associated time point that best predicts irreversible cardiac arrest or the chances of ROSC and survival.Davis and coauthors have exported data from defibrillators used in the resuscitation of 145 OHCA patients and analysed the compression pauses, electrocardiogram (ECG) rhythm, ETCO2 values and the presence of palpable pulses.18Davis D.P. Sell R.E. Wilkes N. et al.Electrical and mechanical recovery of cardiac function following out-of-hospital cardiac arrest.Resuscitation. 2013; 84: 25-30Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar A prepause heart rate threshold of >40 beats min−1 and ETCO2 threshold of >20 mmHg established a decision guideline predicted palpable pulses during compressions with a positive predictive value of 95% and negative predictive value of 99%. Importantly, use of this guideline may reduce the number of unnecessary compression pauses during CPR.Oxygen is essential for life but how much is needed may vary according to the circumstances. Spindelboeck and colleagues from Austria reviewed oxygen partial pressure values in arterial blood (PaO2) taken during CPR in 145 OHCA patients. They observed that a higher PaO2 during CPR was associated with increased survival to hospital admission.19Spindelboeck W. Schindler O. Moser A. et al.Increasing arterial oxygen partial pressure during cardiopulmonary resuscitation is associated with improved rates of hospital admission.Resuscitation. 2013; 84: 770-775Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar This supports current guidance to give as much oxygen as possible during CPR and then adjust to maintain normal oxygen levels after ROSC. In a useful finding for future research efforts, Young and colleagues reported that the inspired oxygen concentration could be effectively titrated by adjusting the oxygen flow when using a standard self-inflating bag and reservoir in a bench lung model.20Young P. Pilcher J. Patel M. et al.Delivery of titrated oxygen via a self-inflating resuscitation bag.Resuscitation. 2013; 84: 391-394Abstract Full Text Full Text PDF PubMed Scopus (16) Google ScholarThe observation that ischaemic interventions both before, during or after an ischaemic insult can protect against reperfusion injury is a promising area for future cardiac arrest therapies. In a pig model of prolonged untreated VF cardiac arrest, Yannopoulos and colleagues showed that ischaemic post-conditioning consisting of four 20 s pauses during the first three minutes of CPR (‘stutter CPR’) was associated with both cardiac and neurological protection and increased survival.21Yannopoulos D. Segal N. Matsuura T. et al.Ischemic post-conditioning and vasodilator therapy during standard cardiopulmonary resuscitation to reduce cardiac and brain injury after prolonged untreated ventricular fibrillation.Resuscitation. 2013; 84: 1143-1149Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar These exciting findings challenge our current practice of minimising interruptions in CPR.1.5 Mechanical devicesImportant new information emerged during 2013 on the challenges and advantages of using mechanical devices to perform chest compression during CPR. Huang and co-workers analysed 37 video recordings in which a mechanical device was used during emergency department resuscitation and found that rescuers spent a prolonged time deploying the device (mean 123 ± 58 s) leading to long no-flow times.22Huang E.P. Wang H.C. Ko P.C. et al.Obstacles delaying the prompt deployment of piston-type mechanical cardiopulmonary resuscitation devices during emergency department resuscitation: a video-recording and time-motion study.Resuscitation. 2013; 84: 1208-1213Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar The data were collected in 2005–2008, and the authors suggested that additional training in device deployment strategies were needed to improve the benefits of mechanical CPR.Following that suggestion, Ong and colleagues23Ong M.E. Quah J.L. Annathurai A. et al.Improving the quality of cardiopulmonary resuscitation by training dedicated cardiac arrest teams incorporating a mechanical load-distributing device at the emergency department.Resuscitation. 2013; 84: 508-514Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar performed an analysis of the quality of CPR as measured by the no-flow ratio in the first 10 min of resuscitation before and after implementation of a trained cardiac arrest team using a pit-crew approach to deployment of a mechanical chest compression device.23Ong M.E. Quah J.L. Annathurai A. et al.Improving the quality of cardiopulmonary resuscitation by training dedicated cardiac arrest teams incorporating a mechanical load-distributing device at the emergency department.Resuscitation. 2013; 84: 508-514Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar The authors were able to demonstrate a significant decrease in the no-flow ratio from 0.33 to 0.23 (decrease = 0.10, 95% CI 0.07–0.14, p < 0.005) using the pit-crew approach.Finally, Omori and associates found that use of a mechanical chest compression device during helicopter transport increased the ROSC rate (30.6% versus 7.0%) and survival to hospital discharge (6.1% versus 2.3%) significantly compared to when the medical crew performed manual chest compression.24Omori K. Sato S. Sumi Y. et al.The analysis of efficacy for AutoPulse system in flying helicopter.Resuscitation. 2013; 84: 1045-1050Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar1.6 Extracorporeal cardiopulmonary resuscitation (eCPR)Extracorporeal CPR (eCPR) can increase the time window for achieving ROSC and identifying and treating a reversible underlying cause. Its use has increased because of improvements in device technology, vascular access and anticoagulation.25Muller T. Lubnow M. The future of E-CPR: a joint venture.Resuscitation. 2013; 84: 1463-1464Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar Lamhaut and colleagues from Paris showed that eCPR can be successfully established prehospital by non-surgeons.26Lamhaut L. Jouffroy R. Soldan M. et al.Safety and feasibility of prehospital extra corporeal life support implementation by non-surgeons for out-of-hospital refractory cardiac arrest.Resuscitation. 2013; 84: 1525-1529Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar The team at the Medical University of Vienna emergency department reported their experiences of eCPR in 55 patients over seventeen years.27Wallmuller C. Sterz F. Testori C. et al.Emergency cardio-pulmonary bypass in cardiac arrest: seventeen years of experience.Resuscitation. 2013; 84: 326-330Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar The median duration of CPR before eCPR was 86 min (IQR 69–121), median ‘cannulation’-time was 33 min (21–45), and duration on circulatory support 311 min (161–953). Eight patients (15%) survived to 6 months with good neurological outcome. Since January 2012, the Erasme University Hospital in Brussels has used eCPR with intra-arrest hypothermia for all witnessed cardiac arrests (in- and out-of-hospital) refractory to standard CPR in patients less than 65 years with no major comorbidities.28Fagnoul D. Taccone F.S. Belhaj A. et al.Extracorporeal life support associated with hypothermia and normoxemia in refractory cardiac arrest.Resuscitation. 2013; 84: 1519-1524Abstract Full Text Full Text PDF PubMed Scopus (73) Google Scholar They report six survivors with good neurological function at 28 days out of 24 eCPR cases.1.7 Adrenaline (epinephrine)The role of adrenaline in cardiac arrest remains controversial. Koscik and colleagues analysed 686 patients with OHCA.29Koscik C. Pinawin A. McGovern H. et al.Rapid epinephrine administration improves early outcomes in out-of-hospital cardiac arrest.Resuscitation. 2013; 84: 915-920Abstract Full Text Full Text PDF PubMed Scopus (60) Google Scholar Early adrenaline defined as 911-call to adrenaline given in ≤10 min was associated with increased ROSC (32.9% versus 23.4%, OR 1.59 [95% CI 1.07–2.38]) but no significant increase in survival to admission or discharge. In his linked editorial, Kudenchuk questions whether even early adrenaline is better than no adrenaline at all, and highlights the need for randomised controlled studies.30Kudenchuk P.J. Early epinephrine in out-of-hospital cardiac arrest: is sooner better than none at all?.Resuscitation. 2013; 84: 861-862Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar A challenge for all observational data is correcting for all possible confounders. Early adrenaline administration can be a marker for other early advanced interventions that are not measured and corrected for. Kudenchuk presents a graph that shows that earlier placebo administration in an amiodarone versus placebo study was associated with improved survival to admission.1.8 Intraosseous accessSantos and colleagues reported data on the pre-hospital use of the EZ-IO® intraosseous device in adults by physicians.31Santos D. Carron P.N. Yersin B. Pasquier M. EZ-IO® intraosseous device implementation in a pre-hospital emergency service: a prospective study and review of the literature.Resuscitation. 2013; 84: 440-445Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar Intraosseous access was needed in only 0.7% of occasions. Access was successful in 54 of 60 (90%) insertion attempts. The indications were primary cardiac arrest (62%), traumatic cardiac arrest (12%), major trauma (12%), shock (5%), acute respiratory distress (3%), severe hypoglycemia (3%), and status epilepticus (2%). The commonest drugs given were adrenaline, atropine, and amiodarone. As Lyon and Donald point out in the linked editorial, the lack of evidence supporting drug use during CPR means that the benefits of intraosseous access in cardiac arrest may be limited to very few cases.32Lyon R.M. Donald M. Intraosseous access in the prehospital setting-ideal first-line option or best bailout?.Resuscitation. 2013; 84: 405-406Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar They add that intraosseous access is a safe, effective means of gaining pre-hospital access to the circulation, but further studies are needed in its use in major trauma, infusing blood components, use in infants, and how to train.2. Post-resuscitation care2.1 Post-cardiac arrest syndromeMultiple organ dysfunction is common among post-cardiac arrest patients. Grimaldi and colleagues studied 21 post-cardiac arrest patients and showed that urinary intestinal fatty acid-binding protein, a biomarker of intestinal permeability, was very high at admission and that whole blood endotoxin values were raised in 86% of patients.33Grimaldi D. Guivarch E. Neveux N. et al.Markers of intestinal injury are associated with endotoxemia in successfully resuscitated patients.Resuscitation. 2013; 84: 60-65Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar Endotoxin values increased between admission and day two in patients with post-resuscitation shock. Given the high incidence of sepsis among post-cardiac arrest patients, some have suggested that prophylactic antibiotics may be beneficial. In a retrospective study, Davies and co-workers showed that among 138 OHCA patients, those who received antibiotics during the first 7 days of their ICU stay had a significantly lower mortality rate than those who did not receive antibiotics (56.6% versus 75.3%; p = 0.025).34Davies K.J. Walters J.H. Kerslake I.M. Greenwood R. Thomas M.J. Early antibiotics improve survival following out-of hospital cardiac arrest.Resuscitation. 2013; 84: 616-619Abstract Full Text Full Text PDF PubMed Scopus (51) Google Scholar Omar and co-investigators used sidestream darkfield microscopy to study the sublingual microcirculation in 30 post-cardiac arrest patients and compared them with 16 patients with septic shock and 9 healthy controls.35Omar Y.G. Massey M. Andersen L.W. et al.Sublingual microcirculation is impaired in post-cardiac arrest patients.Resuscitation. 2013; 84: 1717-1722Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar Microcirculatory flow among the post-cardiac arrest patients was lower than that in both the healthy controls and the patients with septic shock. Better microcirculatory flow was associated with better neurological outcome.2.2 Targeted temperature managementPost-cardiac arrest hyperthermia is associated with worse neurological outcome. Gebhardt and associates reviewed retrospectively 336 OHCA patients and documented fever (≥38 °C) among 42%, with a post-arrest median onset of 15 h in those not treated with targeted temperature management (TTM) and 36 h in the TTM cohort.36Gebhardt K. Guyette F.X. Doshi A.A. Callaway C.W. Rittenberger J.C. Post Cardiac Arrest Service Prevalence and effect of fever on outcome following resuscitation from cardiac arrest.Resuscitation. 2013; 84: 1062-1067Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar Contrary to previous studies, fever was not associated with neurological outcome in any of the cohorts, but was associated with survival in the non-TTM cohort (OR 0.47, 95% CI 0.20–1.10). Leary and co-investigators studied retrospectively a cohort of 236 post-arrest patients treated with TTM.37Leary M. Grossestreuer A.V. Iannacone S. et al.Pyrexia and neurologic outcomes after therapeutic hypothermia for cardiac arrest.Resuscitation. 2013; 84: 1056-1061Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar Rebound pyrexia occurred in 41% but was not associated with lower survival to discharge or worsened neurological outcomes; however, among patients with pyrexia, higher maximum temperature (>38.7 °C) was associated with worse neurological outcomes among survivors to hospital discharge.After a period of active cooling, rewarming is undertaken very carefully because of the known risk of rebound hyperthermia. Bro-Jeppesen and colleagues have studied the incidence of post-hypothermia fever (≥38.5 °C) and its impact on outcome.38Bro-Jeppesen J. Hassager C. Wanscher M. et al.Post-hypothermia fever is associated with increased mortality after out-of-hospital cardiac arrest.Resuscitation. 2013; 84: 1734-1740Abstract Full Text Full Text PDF PubMed Scopus (105) Google Scholar Among 270 patients resuscitated after OHCA and surviving a TTM protocol for at least 24 h, 50% developed post-hypothermia fever – the 30-day mortality in this cohort was 36% compared with 22% in the cohort without post-hypothermia fever (hazard rate adjusted for potential confounders = 1.8 (95% CI 1.1–2.7)). In another study topic on the same topic, Winters and co-investigators also documented an association between post-hypothermia fever (≥38.5 °C) and worse neurological outcome among 141 OHCA patients.39Winters S.A. Wolf K.H. Kettinger S.A. Seif E.K. Jones J.S. Bacon-Baguley T. Assessment of risk factors for post-rewarming “rebound hyperthermia” in cardiac arrest patients undergoing therapeutic hypothermia.Resuscitation. 2013; 84: 1245-1249Abstract Full Text Full Text PDF PubMed Scopus (36) Google ScholarThe optimal time to initiate therapeutic hypothermia (TH) remains unknown. Diao and colleagues undertook a systematic review and meta-analysis of randomised controlled trials of pre-hospital therapeutic hypothermia with the objective of assessing the effectiveness and safety of this intervention after cardiac arrest.40Diao M. Huang F. Guan J. et al.Prehospital therapeutic hypothermia after cardiac arrest: a systematic review and meta-analysis of randomized controlled trials.Resuscitation. 2013; 84: 1021-1028Abstract Full Text Full Text PDF PubMed Scopus (37) Google Scholar Five studies involving 633 cases were included (314 cases in the treatment group and the 319 in the control group). The authors conclude that pre-hospital therapeutic hypothermia decreased the temperature on hospital admission compared with the control group (mean difference = −0.95 °C; 95% CI −1.15 to −0.75); however, there were no differences in survival or neurological outcome.The use of TTM for comatose survivors of OHCA with an initial shockable rhythm is well established but its use in survivors of in-hospital cardiac arrest (IHCA) is less well accepted. In an analysis of 8316 patients with complete data in the AHA GWTG-R registry, Nichol and coauthors have shown that TTM was used in just 2.6% and, of these, only 40% achieved a temperature between 32 °C and 34 °C.41Nichol G. Huszti E. Kim F. et al.Does induction of hypothermia improve outcomes after in-hospital cardiac arrest?.Resuscitation. 2013; 84: 620-625Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar Induced hypothermia was not associated with improved or worsened survival or neurologically favourable survival.The optimal cooling method remains unclear; however, Testori and associates reported a series of eight OHCA patients treated with extracorporeal veno-venous cooling, in whom the core temperature was reduced from a median of 35.9 °C to less than 34 °C in a median time of 8 min (interquartile range 5–15 min) – this must represent the fastest cooling rate achievable in post-arrest patients.42Testori C. Holzer M. Sterz F. et al.Rapid induction of mild therapeutic hypothermia by extracorporeal veno-venous blood cooling in humans.Resuscitation. 2013; 84: 1051-1055Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar High-quality TTM requires accurate and continuous monitoring of core temperature. In series of 21 patients, Shin and co-workers monitored temperature during TTM in four sites: bladder, rectum, tympanic membrane and pulmonary artery (PA).43Shin J. Kim J. Song K. Kwak Y. Core temperature measurement in therapeutic hypothermia according to different phases: comparison of bladder, rectal, and tympanic versus pulmonary artery methods.Resuscitation. 2013; 84: 810-817Abstract Full Text Full Text PDF PubMed Scopus (46) Google Scholar In comparison with the rectum and tympanum, the temperature measured in the bladder most closely reflected that in the PA. During cooling, the rectal temperature is significantly higher than the PA temperature and should not be used during TTM. Many clinicians use non-invasive cardiac output monitoring in post-cardiac arrest patients and among the available methods the Pulse Contour Cardiac Output (PiCCO)