Faculty Bibliography

PURPOSE OF REVIEW: To provide a summary of the recent literature on clinical outcomes in adults with cardiac arrest, focusing on the impact of patient-specific factors in combination with cardio-pulmonary resuscitation (CPR) related, and postresuscitative-related factors. RECENT FINDINGS: Cardiac arrest is a major cause of morbidity and mortality worldwide. Despite the use of conventional cardiopulmonary resuscitation, rates of return of spontaneous circulation and survival with minimal neurologic impairment remain low. A number of recent studies have examined the impact of patient-specific factors (duration of cardiac arrest, initial rhythm, age, premorbid states), CPR-related (the use of mechanical CPR, the use of impedance threshold device, vasopressors, extra-corporeal membrane oxygenation, active compression-decompression, and impedance threshold device), and postresuscitative-related factors (hypothermia, coronary angiography, hyperoxia, hyper/hypocapnia, mean arterial blood pressure) on cardiac arrest outcomes. SUMMARY: Further studies, namely randomized controlled trials, assessing the impact of advanced therapies are warranted to evaluate their impact on survival and neurologic function in adults with cardiac arrest.

OBJECTIVES: Cerebral oximetry using near-infrared spectroscopy measures regional cerebral oxygen saturation (rSO2) non-invasively and may provide information regarding the quality of cerebral oxygen perfusion. We determined whether the level of rSO2 obtained during cardiopulmonary resuscitation is associated with return of spontaneous circulation (ROSC) and survival in Emergency Department (ED) patients presenting with cardiac arrest. METHODS: We conducted a retrospective, observational study of adult ED patients presenting at an academic medical centre with cardiac arrest in whom continuous cerebral oximetry was performed. Demographic and clinical data including age, gender, presenting rhythm and mean rSO2 readings were abstracted. Cerebral oxygenation was measured with a commercially available oximeter. RESULTS: A convenience study sample included 59 patients ages 18-102 years (mean age 68.7+/-14.9 years); 50 (84.7%) were men. Presenting rhythms included pulseless electrical activity (21), asystole (20) and ventricular fibrillation/tachycardia (17). 24 patients (40.6%) had ROSC and only 1 (1.7%) survived to hospital discharge. Patients with and without ROSC were similar in age and presenting cardiac rhythms. The mean of mean rSO2 levels was higher in patients with ROSC, 43.8 (95% CI 40.1 to 47.6) compared with those without ROSC, 34.2 (95% CI 30.6 to 37.8); p=0.001. 91.7% of patients with ROSC had a rSO2 of 30% or greater compared with 62.9% in those without ROSC (p=0.01). The area under the curve for mean rSO2 as a predictor of ROSC was 0.76 (95% CI 0.64 to 0.89). CONCLUSIONS: In ED patients with cardiac arrest higher cerebral oxygen saturations are associated with higher rates of ROSC.

BACKGROUND: Cardiac arrest (CA) survivors experience cognitive deficits including post-traumatic stress disorder (PTSD). It is unclear whether these are related to cognitive/mental experiences and awareness during CPR. Despite anecdotal reports the broad range of cognitive/mental experiences and awareness associated with CPR has not been systematically studied. METHODS: The incidence and validity of awareness together with the range, characteristics and themes relating to memories/cognitive processes during CA was investigated through a 4 year multi-center observational study using a three stage quantitative and qualitative interview system. The feasibility of objectively testing the accuracy of claims of visual and auditory awareness was examined using specific tests. The outcome measures were (1) awareness/memories during CA and (2) objective verification of claims of awareness using specific tests. RESULTS: Among 2060 CA events, 140 survivors completed stage 1 interviews, while 101 of 140 patients completed stage 2 interviews. 46% had memories with 7 major cognitive themes: fear; animals/plants; bright light; violence/persecution; deja-vu; family; recalling events post-CA and 9% had NDEs, while 2% described awareness with explicit recall of 'seeing' and 'hearing' actual events related to their resuscitation. One had a verifiable period of conscious awareness during which time cerebral function was not expected. CONCLUSIONS: CA survivors commonly experience a broad range of cognitive themes, with 2% exhibiting full awareness. This supports other recent studies that have indicated consciousness may be present despite clinically undetectable consciousness. This together with fearful experiences may contribute to PTSD and other cognitive deficits post CA.

Advances in resuscitation science have indicated that, contrary to perception, death by cardiorespiratory criteria can no longer be considered a specific moment but rather a potentially reversible process that occurs after any severe illness or accident causes the heart, lungs, and brain to stop functioning. The resultant loss of vital signs of life (and life processes) is used to declare a specific time of death by physicians globally. When medical attempts are made to reverse this process, it is commonly referred to as cardiac arrest; however, when these attempts do not succeed or when attempts are not made, it is called death by cardiorespiratory criteria. Thus, biologically speaking, cardiac arrest and death by cardiorespiratory criteria are synonymous. While resuscitation science has provided novel opportunities to reverse death by cardiorespiratory criteria and treat the potentially devastating consequences of the resultant postresuscitation syndrome, it has also inadvertently provided intriguing insights into the likely mental and cognitive experience of death. Recollections reported by millions of people in relation to death, so-called out-of-body experiences (OBEs) or near-death experiences (NDEs), are often-discussed phenomena that are frequently considered hallucinatory or illusory in nature; however, objective studies on these experiences are limited. To date, many consistent themes corresponding to the likely experience of death have emerged, and studies have indicated that the scientifically imprecise terms of NDE and OBE may not be sufficient to describe the actual experience of death. While much remains to be discovered, the recalled experience surrounding death merits a genuine scientific investigation without prejudice.

Breakthroughs in emergency medicine have enabled science to halt and even reverse death. However, these advances have inadvertently led science into a domain that has traditionally been the purview of theology and philosophy. Steve Paulson, executive producer and host of To the Best of Our Knowledge, moderated a discussion that included emergency medicine experts Lance B. Becker and Sam Parnia, and neurosurgeon Stephan A. Mayer; they discussed recent discoveries and emerging technologies in resuscitation science and the ethical dilemmas they sometimes confront during medical crises. The following is an edited transcript of the discussion from October 9, 2013, 7:00-8:30 PM, at the New York Academy of Sciences in New York City.

For millennia, human beings have wondered what happens after death. What is the first-person experience of dying and being brought back to life? Technological advances in resuscitation science have now added an intriguing new chapter to the literature of out-of-body or near-death experiences by eliciting detailed and vivid accounts of those who have approached the threshold of death. Steve Paulson, executive producer and host of To the Best of Our Knowledge, moderated a discussion that included neurologist Kevin Nelson, neuropsychiatrist Peter Fenwick, emergency medicine expert Sam Parnia, and orthopedic surgeon and drowning survivor Mary Neal; they share some remarkable stories and discuss how they analyze such experiences in light of their own backgrounds and training. The following is an edited transcript of the discussion from December 11, 2013, 7:00-8:30 PM, at the New York Academy of Sciences in New York City.