Justin Lundbye

Therapeutic hypothermia is associated with improved neurologic outcome and survival in cardiac arrest survivors of non-shockable rhythms

BACKGROUND Therapeutic hypothermia improves neurologic outcomes in patients resuscitated from cardiac arrest due to ventricular fibrillation. However, its role in patients with cardiac arrest due to non-shockable rhythms (pulseless electrical activity (PEA) and asystole) is unclear. We hypothesized that therapeutic hypothermia favorably impacts neurologic outcome and survival in patients resuscitated from cardiac arrest due to non-shockable rhythms. METHODS Retrospectively collected data on consecutive adult patients admitted to Hartford Hospital from 1/1/2004 to 11/1/2010 who survived a cardiac arrest due to PEA or asystole were analyzed. Patients who underwent therapeutic hypothermia (1/1/2007-11/1/2010) formed the hypothermia group while patients admitted prior to the institution of therapeutic hypothermia (1/1/2004-1/1/2007) at Hartford Hospital formed the control group. The primary end-point was measured using the Pittsburgh cerebral performance category (CPC) scale and patients were assessed for a good (CPC 1 and 2) or poor (CPC 3-5) neurological outcome prior to discharge from hospital. A secondary end-point was measured as survival at discharge from hospital. RESULTS Of 100 post-cardiac arrest patients included in the study, 15/52 (29%) patients in the hypothermia group had a good neurologic outcome as compared to 5/43 (10%) patients in the control group (P=0.021). On multivariate analysis, the odds ratio for good neurologic outcome and survival at discharge from the hospital with therapeutic hypothermia as compared to control were 4.35 (95% CI 1.10-17.24, P=0.04) and 5.65 (CI 1.66-19.23, P=0.006) respectively. CONCLUSION Therapeutic hypothermia is associated with favorable neurologic outcome and survival in patients resuscitated after cardiac arrest due to non-shockable rhythms.

The impact of severe acidemia on neurologic outcome of cardiac arrest survivors undergoing therapeutic hypothermia

INTRODUCTION Therapeutic Hypothermia (TH) has become a standard of care in improving neurological outcomes in cardiac arrest (CA) survivors. Previous studies have defined severe acidemia as plasma pH<7.20. We investigated the influence of severe acidemia at the time of initiation of TH on neurological outcome in CA survivors. METHODS A retrospective analysis was performed on 196 consecutive CA survivors (out-of-hospital CA and in-hospital CA) who underwent TH with endovascular cooling between January 2007 and October 2012. Arterial blood gas drawn prior to initiation of TH was utilized to measure pH in all patients. Shockable and non-shockable CA patients were divided into two sub-groups based on pH (pH<7.2 and pH≥7.2). The primary end-point was measured using the Pittsburgh Cerebral Performance Category (CPC) scale prior to discharge from the hospital: good (CPC 1 and 2) and poor (CPC 3 to 5) neurologic outcome. RESULTS Sixty-two percent of shockable CA patients with pH≥7.20 had good neurological outcome as compared to 34% patients with pH<7.20. Shockable CA patients with pH≥7.20 were 3.3 times more likely to have better neurological outcome when compared to those with pH <7.20 [p=0.013, OR 3.3, 95% CI (1.28-8.45)]. In comparison, non-shockable CA patients with p≥7.20 did not have a significantly different neurological outcome as compared to those with pH<7.20 [p=0.97, OR 1.02, 95% CI (0.31-3.3)]. CONCLUSION Presence of severe acidemia at initiation of TH in shockable CA survivors is significantly associated with poor neurological outcomes. This effect was not observed in the non-shockable CA survivors.

Managing the Complications of Mild Therapeutic Hypothermia in the Cardiac Arrest Patient

Mild therapeutic hypothermia (MTH) is used to lower the core body temperature of cardiac arrest (CA) patients to 32°C from 34°C to provide improved survival and neurologic outcomes after resuscitation from in-hospital or out-of-hospital CA. Despite the improved benefits of MTH, there are potentially unforeseen complications associated during management. Although the adverse effects are transient, the clinician should be aware of the associated complications when managing the patient receiving MTH. We aim to provide the medical community comprehensive information related to the potential complications of survivors of CA receiving MTH, as it is imperative for the clinician to understand the physiologic changes that take place in the patient receiving MTH and how to prepare for them and manage them if they do occur. We hope to provide information of how to manage these potential complications through both a review of the current literature and a reflection of our own experience.

The use of hypothermia therapy in cardiac arrest survivors.

The annual incidence of out-of-hospital cardiac arrests in the United States is ∼350,000-450,000 per year. The prognosis for cardiac arrest survivors remains extremely poor. Therapeutic hypothermia (TH) is the only therapy proven to improve survival and neurological outcome in these patients. This article discusses the pathophysiology of neurological injury in cardiac arrest survivors and states the presumed mechanisms by which TH mitigates brain injury in these patients. It reviews the contraindications to the use of this therapy, methods of cooling, and phases of TH and elaborates on the intensive care unit management of TH. The use of TH in ventricular fibrillation survivors has become the standard of care and continues to evolve in its application as an essential therapy in cardiac arrest patients.

Clinical Studies Targeting Stroke and Ischemic Insults

During the Sixth Annual Therapeutic Hypothermia and Temperature Management Meeting in Miami, an expert panel discussion on the continued use of therapeutic hypothermia for stroke and cerebral ischemia was organized. The moderator was Dr. Justin Lundbye, Hospital of Central Connecticut, New Britain, Connecticut, Dr. Patrick Lyden, Department of Neurology, Cedars-Medical Center, Los Angeles California, discussed the ICTuS two final results on the use of thrombolysis and hypothermia to improve outcomes in acute stroke patients. Primary and secondary outcome measures were summarized, as well as safety issues. Dr. Kees Polderman, Department of Critical Care, University of Pittsburgh Medical Center, discussed the use of hypothermia in cardiogenic and septic shock. For this lecture, topics also included the effects of temperature on heart and vascular tone, as well as renal function. Dr. Stefan Schwab, Department of Neurology, Friedrich-Alexander University, Erlangen, spoke on the use of hypothermia in acute intracerebral hemorrhage. Topics included the pathogenesis of clinical ICH, as well as encouraging preclinical findings. The methods and outcome measures used in the TTM-ICH pilot clinical study were summarized and outcome measures and results discussed. This expert panel discussion was very informative and touched upon some new questions and ideas regarding the use of therapeutic hypothermia targeting this patient population.

Proceedings of the ASNC Cardiac PET Summit, 12 May 2014, Baltimore, MD

a Gagnon Cardiovascular Institute, Morristown Medical Center, Morristown, NJ b The Saint-Luke’s Cardiovascular Consultants, Kansas City, MO c Department of Nuclear Medicine, Cleveland Clinic Foundation, Cleveland, OH d Department of Nuclear Medicine, St. Luke’s Hospital, New York, NY e Department of Radiology, Emory University, Atlanta, GA f Department of Cardiology, Hospital of Central Connecticut, New Britain, CT g American Society of Nuclear Cardiogy, Bethesda, MD h Medaxiom, South Lyon, MI

THE IMPACT OF THERAPEUTIC HYPOTHERMIA ON SERUM POTASSIUM

Therapeutic hypothermia (TH) has been shown to improve survival and neurological outcome in patients resuscitated from cardiac arrest. Electrolyte disturbances and especially hypokalemia are commonly noted during TH. Experimental data suggest that transient potassium (K) shifts into cells may be

Endovascular catheter as a rewarming method for accidental hypothermia.

The human body functions within a very narrow range of optimal core body temperature. Mechanisms are in place that enable it to thermoregulate despite large fluctuations in external temperature. Going beyond the normal physiologic range is poorly tolerated. Profound hypothermia is a devastating condition that warrants prompt recognition and management. This is a case of an 89-year-old man who was admitted for altered mental status. On arrival, the patient was found to be bradycardic, hypotensive, and hypothermic at 28.8°C. Warmed saline and vasopressors were started; an Icy catheter connected to a Zoll Coolgard was placed in the vena cava via the femoral vein and the patient was rewarmed at a rate of 1°C without complications. He was later transferred out of the coronary care unit hemodynamically stable. Although there are no clinical practice guidelines in place, severe hypothermia has been traditionally managed with invasive and aggressive rewarming techniques; endovascular catheters as an alternative for rapid and controlled rewarming may be a worthy and safe alternative to these more invasive procedures.

Effect of Neuromuscular Blockers on Outcomes in Patients Receiving Therapeutic Hypothermia Following Cardiac Arrest

Effect of Neuromuscular Blockers on Outcomes in Patients Receiving Therapeutic Hypothermia Following Cardiac Arrest The use of mild therapeutic hypothermia therapy (MTH) for the preservation of neurological function and improvement in survival after cardiac arrest has been well established. Complications of MTH include electrolyte shifting, hypercoagulability, hyperglycemia, and seizures, among others. Additionally, the prevention of shivering is important as it can negate the beneficial effects of MTH through a variety of mechanisms. These include increased oxygen consumption, increased metabolic demands, and increases in intracranial pressure. Current guidelines and numerous clinical trial protocols recommend the use of sedatives and neuromuscular blockers (NMBs) to prevent shivering during initial cooling.

Temperature management in neurological and neurosurgical intensive care units.

The use of temperature management in neurological and neurosurgical intensive care units (ICU) has gained acceptance and resulted in better outcomes in some patient populations. In various studies of out-of-hospital cardiac arrest as well as traumatic brain injury, directed temperature management protocols in the ICU have led to reductions in periods of reactive hyperthermia that occur in many patients with severe injuries. In addition, lowering the temperature to various levels of hypothermia also appears to reduce secondary injury mechanisms, intracranial pressure levels, and edema formation. Nevertheless, controversies exist in what patient population we should cool and what level of cooling is most appropriate in neurological settings. A series of stateof-the-art lectures presented at the 2014 Therapeutic Hypothermia and Temperature Management meeting in Miami brought together experts in the field of therapeutic hypothermia and temperature management strategies to discuss this important topic. Dr. Kees Polderman, Department of Critical Care, University of Pittsburgh School of Medicine, Pittsburgh, PA, provided new information regarding the reasons to cool patients and new strategies for cooling awake patients, which is an important clinical question. In the awake state, patients shiver and this can produce barriers to reducing temperature effectively and making the patient comfortable. Dr. Kelley Lockhart, Department of Internal Medicine, Abbott Northwestern Hospital, Minneapolis, MN, emphasized the potentially detrimental effects of fever in various patient populations, including subarachnoid hemorrhage. In these patients specifically, 70% develop fever during the first 10 days. Although it is difficult to determine causes underlying elevations in temperature, hyperthermia continues to be a risk factor that may be controlled by targeted temperature management. Dr. Neeraj Badjatia, Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, described novel approaches to monitor degrees of shivering in patient populations. Continuing studies are directed toward understanding the clinical relevance of shivering as well as antishivering strategies that may allow cooling to be introduced in the awake subject. It is clear that as therapeutic hypothermia and temperature management strategies are increasingly used by many caregivers, these types of questions are becoming more and more important to define and provide suitable strategies for better outcomes.