Sam Parnia

A feasibility study evaluating the role of cerebral oximetry in predicting return of spontaneous circulation in cardiac arrest.

UNLABELLED To date there has been no reliable noninvasive real time monitoring available to determine cerebral perfusion during cardiac arrest. OBJECTIVES To investigate the feasibility of using a commercially available cerebral oximeter during in-hospital cardiac arrest, and determine whether this parameter predicts return of spontaneous circulation (ROSC). METHODS Cerebral oximetry was incorporated in cardiac arrest management in 19 in-hospital cardiac arrest cases, five of whom had ROSC. The primary outcome measure was the relationship between rSO(2) and ROSC. RESULTS The use of cerebral oximetry was found to be feasible during in hospital cardiac arrest and did not interfere with management. Patients with ROSC had a significantly higher overall mean ± SE rSO(2) (35 ± 5 vs. 18 ± 0.4, p<0.001). The difference in mean rSO(2) between survivors and non-survivors was most pronounced in the final 5 min of cardiac arrest (48 ± 1 vs. 15 ± 0.2, p<0.0001) and appeared to herald imminent ROSC. Although spending a significantly higher portion of time with an rSO(2)>40% was found in survivors (p<0.0001), patients with ROSC had an rSO(2) above 30% for >50% of the duration of cardiac arrest, whereas non-survivors had an rSO(2) that was below 30%>50% of their cardiac arrest. Patients with ROSC also had a significantly higher change in rSO(2) from baseline compared to non-survivors (310% ± 60% vs. 150% ± 27%, p<0.05). CONCLUSION Cerebral oximetry may have a role in predicting ROSC and the optimization of cerebral perfusion during cardiac arrest.

A feasibility study of cerebral oximetry during in-hospital mechanical and manual cardiopulmonary resuscitation*.

Objective:A major hurdle limiting the ability to improve the quality of resuscitation has been the lack of a noninvasive real-time detection system capable of monitoring the quality of cerebral and other organ perfusion, as well as oxygen delivery during cardiopulmonary resuscitation. Here, we report on a novel system of cerebral perfusion targeted resuscitation. Design:An observational study evaluating the role of cerebral oximetry (Equanox; Nonin, Plymouth, MI, and Invos; Covidien, Mansfield, MA) as a real-time marker of cerebral perfusion and oxygen delivery together with the impact of an automated mechanical chest compression system (Life Stat; Michigan Instruments, Grand Rapids, MI) on oxygen delivery and return of spontaneous circulation following in-hospital cardiac arrest. Setting:Tertiary medical center. Patients:In-hospital cardiac arrest patients (n = 34). Main Results:Cerebral oximetry provided real-time information regarding the quality of perfusion and oxygen delivery. The use of automated mechanical chest compression device (n = 12) was associated with higher regional cerebral oxygen saturation compared with manual chest compression device (n = 22) (53.1% ± 23.4% vs 24% ± 25%, p = 0.002). There was a significant difference in mean regional cerebral oxygen saturation (median % ± interquartile range) in patients who achieved return of spontaneous circulation (n = 15) compared with those without return of spontaneous circulation (n = 19) (47.4% ± 21.4% vs 23% ± 18.42%, p < 0.001). After controlling for patients achieving return of spontaneous circulation or not, significantly higher mean regional cerebral oxygen saturation levels during cardiopulmonary resuscitation were observed in patients who were resuscitated using automated mechanical chest compression device (p < 0.001). Conclusions:The integration of cerebral oximetry into cardiac arrest resuscitation provides a novel noninvasive method to determine the quality of cerebral perfusion and oxygen delivery to the brain. The use of automated mechanical chest compression device during in-hospital cardiac arrest may lead to improved oxygen delivery and organ perfusion.

A pilot study examining the role of regional cerebral oxygen saturation monitoring as a marker of return of spontaneous circulation in shockable (VF/VT) and non-shockable (PEA/Asystole) causes of cardiac arrest

BACKGROUND Non-invasive monitoring of cerebral perfusion and oxygen delivery during cardiac arrest is not routinely utilized during cardiac arrest resuscitation. The objective of this study was to investigate the feasibility of using cerebral oximetry during cardiac arrest and to determine the relationship between regional cerebral oxygen saturation (rSO2) with return of spontaneous circulation (ROSC) in shockable (VF/VT) and non-shockable (PEA/asystole) types of cardiac arrest. METHODS Cerebral oximetry was applied to 50 in-hospital and out-of-hospital cardiac arrest patients. RESULTS Overall, 52% (n=26) achieved ROSC and 48% (n=24) did not achieve ROSC. There was a significant difference in mean±SD rSO2% in patients who achieved ROSC compared to those who did not (47.2±10.7% vs. 31.7±12.8%, p<0.0001). This difference was observed during asystole (median rSO2 (IQR) ROSC versus no ROSC: 45.0% (35.1-48.8) vs. 24.9% (20.5-32.9), p<0.002) and PEA (50.6% (46.7-57.5) vs. 31.6% (18.8-43.3), p=0.02), but not in the VF/VT subgroup (43.7% (41.1-54.7) vs. 42.8% (34.9-45.0), p=0.63). Furthermore, it was noted that no subjects with a mean rSO2<30% achieved ROSC. CONCLUSIONS Cerebral oximetry may have a role as a real-time, non-invasive predictor of ROSC during cardiac arrest. The main utility of rSO2 in determining ROSC appears to apply to asystole and PEA subgroups of cardiac arrest, rather than VF/VT. This observation may reflect the different physiological factors involved in recovery from PEA/asytole compared to VF/VT. Whereas in VF/VT, successful defibrillation is of prime importance, however in PEA and asytole achieving ROSC is more likely to be related to the quality of oxygen delivery. Furthermore, a persistently low rSO2 <30% in spite of optimal resuscitation methods may indicate futility of resuscitation efforts.

Does induction of hypothermia improve outcomes after in-hospital cardiac arrest?

INTRODUCTION Hypothermia improves neurologic recovery compared to normothermia after resuscitation from out-of-hospital ventricular fibrillation, but may or may not be beneficial for patients resuscitated from in-hospital cardiac arrest. Therefore, we evaluated the effect of induced hypothermia in a large cohort of patients with in-hospital cardiac arrest. METHODS Retrospective analysis of multi-center prospective cohort of patients with in-hospital cardiac arrest enrolled in an ongoing quality improvement project. Included were adults with a pulseless event in an in-patient hospital ward of a participating institution who achieved restoration of spontaneous circulation between 2000 and 2009. The exposure of interest was induced hypothermia. The primary outcome was survival to discharge. The secondary outcome was neurological status at discharge. Analyses evaluated all eligible patients; those with a shockable rhythm; or those with endotracheal tube inserted after resuscitation; and the effect of no hypothermia versus hypothermia (lowest temperature>32 °C but ≤34 °C) versus overcooled (≤32 °C). Associations were assessed using propensity score methods. RESULTS Included were 8316 patients with complete data, of whom 214 (2.6%) had hypothermia induced and 2521 (30%) survived to discharge. Of patients reported to receive hypothermia, only 40% were documented as achieving a temperature between 32 °C and 34 °C. Adjusted for known potential confounders using propensity score methods, induced hypothermia was associated with an odds ratio of survival of 0.90 (95% confidence interval: 0.65, 1.23; p-value=0.49) compared to no hypothermia. Induced hypothermia was associated with an odds ratio of neurologically-favorable survival of 0.93 (95% confidence interval: 0.65, 1.32; p-value=0.68) compared to no hypothermia. For patients with shockable first-recorded rhythm, induced hypothermia was associated with an odds ratio of survival of 1.43 (95% confidence interval: 0.68, 3.01; p-value=0.35) compared to no hypothermia. CONCLUSION Hypothermia is induced infrequently in patients resuscitated from in-hospital cardiac arrest with only 40% achieving target temperatures. Induced hypothermia was not associated with improved or worsened survival or neurologically-favorable survival. The lack of benefit in this population may reflect lack of effect, inefficient application of the intervention, or residual confounding. High-quality controlled studies are required to better characterize the effect of induced hypothermia in this population.

Cerebral Oximetry During Cardiac Arrest: A Multicenter Study of Neurologic Outcomes and Survival.

Objectives: Cardiac arrest is associated with morbidity and mortality because of cerebral ischemia. Therefore, we tested the hypothesis that higher regional cerebral oxygenation during resuscitation is associated with improved return of spontaneous circulation, survival, and neurologic outcomes at hospital discharge. We further examined the validity of regional cerebral oxygenation as a test to predict these outcomes. Design: Multicenter prospective study of in-hospital cardiac arrest. Setting: Five medical centers in the United States and the United Kingdom. Patients: Inclusion criteria are as follows: in-hospital cardiac arrest, age 18 years old or older, and prolonged cardiopulmonary resuscitation greater than or equal to 5 minutes. Patients were recruited consecutively during working hours between August 2011 and September 2014. Survival with a favorable neurologic outcome was defined as a cerebral performance category 1–2. Interventions: Cerebral oximetry monitoring. Measurements and Main Results: Among 504 in-hospital cardiac arrest events, 183 (36%) met inclusion criteria. Overall, 62 of 183 (33.9%) achieved return of spontaneous circulation, whereas 13 of 183 (7.1%) achieved cerebral performance category 1–2 at discharge. Higher mean ± SD regional cerebral oxygenation was associated with return of spontaneous circulation versus no return of spontaneous circulation (51.8% ± 11.2% vs 40.9% ± 12.3%) and cerebral performance category 1–2 versus cerebral performance category 3–5 (56.1% ± 10.0% vs 43.8% ± 12.8%) (both p < 0.001). Mean regional cerebral oxygenation during the last 5 minutes of cardiopulmonary resuscitation best predicted the return of spontaneous circulation (area under the curve, 0.76; 95% CI, 0.69–0.83); regional cerebral oxygenation greater than or equal to 25% provided 100% sensitivity (95% CI, 94–100) and 100% negative predictive value (95% CI, 79–100); regional cerebral oxygenation greater than or equal to 65% provided 99% specificity (95% CI, 95–100) and 93% positive predictive value (95% CI, 66–100) for return of spontaneous circulation. Time with regional cerebral oxygenation greater than 50% during cardiopulmonary resuscitation best predicted cerebral performance category 1–2 (area under the curve, 0.79; 95% CI, 0.70–0.88). Specifically, greater than or equal to 60% cardiopulmonary resuscitation time with regional cerebral oxygenation greater than 50% provided 77% sensitivity (95% CI,:46–95), 72% specificity (95% CI, 65–79), and 98% negative predictive value (95% CI, 93–100) for cerebral performance category 1–2. Conclusions: Cerebral oximetry allows real-time, noninvasive cerebral oxygenation monitoring during cardiopulmonary resuscitation. Higher cerebral oxygenation during cardiopulmonary resuscitation is associated with return of spontaneous circulation and neurologically favorable survival to hospital discharge. Achieving higher regional cerebral oxygenation during resuscitation may optimize the chances of cardiac arrest favorable outcomes.

A feasibility study of cerebral oximetry monitoring during the post-resuscitation period in comatose patients following cardiac arrest.

BACKGROUND One of the major causes of death and neurological injury after cardiac arrest is delayed ischemia combined with oxygen free radical mediated reperfusion injury. Consequently determining the optimal balance between oxygen delivery and uptake in the brain using a reliable non-invasive monitoring system during the post-resuscitation period is of importance. In this observational study, we evaluated the feasibility of using cerebral oximetry during the post-resuscitation period in order to identify changes in regional cerebral oxygen saturation (rSO2) and its association with survival to discharge. METHODS 21 consecutive patients admitted to the intensive care units following cardiac arrest had cerebral oximetry monitoring carried out for 48 h. Mean rSO2 values were collected during the first 24h and then again during the subsequent 24-48 h of the post-resuscitation period. RESULTS 43% (n=9) patients survived to hospital discharge and 57% (n=12) died. Amongst all patients the median (IQR) rSO2% was 65.5% (62.6-68.2) in the first 24-h following ROSC and increased to 72.1% (64.6-73.7) (p=0.11) in the subsequent 24-48 h. The median (IQR) rSO2% during the first 24 h in patients who survived to discharge compared to those who did not survive were significantly higher 68.2% (66.0-71.0) vs. 62.9% (56.5-66.0), p=0.01). During the subsequent 24-48 h period, while a difference in the rSO2 between survivors and non-survivors was noted, this did not achieve statistical significance (median (IQR): 73.7 (70.2-74.0) vs. 66.5 (58.2-72.1), p=0.11). CONCLUSIONS Our study indicates that the use of cerebral oximetry is feasible during the post resuscitation period after cardiac arrest. Further studies are needed to determine whether cerebral oximetry may be used as a novel non-invasive monitoring system to evaluate changes in the balance between cerebral oxygen delivery and uptake during the post-resuscitation period.

Cerebral oximetry levels during CPR are associated with return of spontaneous circulation following cardiac arrest: an observational study

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.

Death and consciousness--an overview of the mental and cognitive experience of death.

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.

Venoarterial Extracorporeal Membrane Oxygenation in Adults With Cardiac Arrest.

Cardiac arrest (CA) is a major cause of morbidity and mortality worldwide. Despite the use of conventional cardiopulmonary resuscitation (CPR), rates of return of spontaneous circulation and survival with minimal neurologic impairment remain low. Utilization of venoarterial extracorporeal membrane oxygenation (ECMO) for CA in adults is steadily increasing. Propensity-matched cohort studies have reported outcomes associated with ECMO use to be superior to that of conventional CPR alone in in-hospital patients with CA. In this review, we discuss the mechanism, indications, complications, and evidence for ECMO in CA in adults.

Cerebral oximetry versus end tidal CO2 in predicting ROSC after cardiac arrest

Study objective: Both end tidal CO2 (ETCO2) and cerebral oxygen saturations (rSO2) have been studied to determine their ability to monitor the effectiveness of CPR and predict return of spontaneous circulation (ROSC). We compared the accuracy of ETCO2 and rSO2 at predicting ROSC in ED patients with out‐of‐hospital cardiac arrest (OHCA). Methods: We performed a prospective, observational study of adult ED patients presenting in cardiac arrest. We collected demographic and clinical data including age, gender, presenting rhythm, rSO2, and ETCO2. We used receiver operating characteristic curves to compare how well rSO2 and ETCO2 predicted ROSC. Results: 225 patients presented to the ED with cardiac arrest between 10/11 and 10/14 of which 100 had both rSO2 and ETCO2 measurements. Thirty three patients (33%) had sustained ROSC, only 2 survived to discharge. The AUCs for rSO2 and ETCO2 were similar (0.69 [95% CI, 0.59–0.80] and 0.77 [95% CI, 0.68–0.86], respectively), however, rSO2 and ETCO2 were poorly correlated (0.12, 95% CI, − 0.08–0.31). The optimal cutoffs for rSO2 and ETCO2 were 50% and 20 mm Hg respectively. At these cutoffs, ETCO2 was more sensitive (100%, 95% CI 87–100 vs. 48%, 31–66) but rSO2 was more specific (85%, 95% CI, 74–92 vs. 45%, 33–57). Conclusions: While poorly correlated, rSO2 and ETCO2 have similar diagnostic characteristics. ETCO2 is more sensitive and rSO2 is more specific at predicting ROSC in OHCA.