Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
EMJ Online First, published on March 24, 2014 as 10.1136/emermed-2013-203467 Original article
Cerebral oximetry levels during CPR are associated with return of spontaneous circulation following cardiac arrest: an observational study Adam J Singer, Anna Ahn, Loren A Inigo-Santiago, Henry C Thode Jr, Mark C Henry, Sam Parnia Resuscitation Research Group, Departments of Emergency Medicine and Medicine, Stony Brook University, Stony Brook, New York, USA Correspondence to Dr Adam J Singer, Department of Emergency Medicine, HSCL4-080, 8350 SUNY, Stony Brook, NY 11794-8350, USA; [email protected] Presented at the Annual Meeting of the Society for Academic Emergency Medicine, Atlanta, GA, May 2013. Received 2 December 2013 Revised 24 January 2014 Accepted 1 February 2014
ABSTRACT 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.
INTRODUCTION
To cite: Singer AJ, Ahn A, Inigo-Santiago LA, et al. Emerg Med J Published Online First: [ please include Day Month Year] doi:10.1136/emermed-2013203467
Each year there are over 350 000 deaths from sudden cardiac arrest (SCA) in the USA alone, which is more than the total number of deaths from Alzheimer’s’ disease, assault with firearms, breast cancer, cervical cancer, colorectal cancer, diabetes, HIV, house fires, motor vehicle accidents, prostate cancer and suicides combined.1 Despite major advances in the understanding of SCA mortality remains high with less than 1 of 10 victims of out-of-hospital SCA surviving to hospital discharge.2 Even among survivors, many are left with significant neurological and cognitive deficits.
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467 Copyright Article author (or their employer) 2014.
Key messages What is already known on this subject? Survival from cardiac arrest is poor and dependent on adequate perfusion of the heart and brain. Currently there are few objective guides for monitoring and optimizing cerebral perfusion in cardiac arrest. What this study adds? This study demonstrates that it is feasible to continuously monitor cerebral oxygenation and perfusion during resuscitation. It also demonstrates an association between improved cerebral oxygenation and return of spontaneous circulation in emergency department patients presenting after out-ofhospital cardiac arrest. Optimization of resuscitation and improved outcomes may be guided by cerebral oximetry.
In order to maximise the effectiveness of cardiopulmonary resuscitation and increase the likelihood that victims of SCA will survive without major neurological deficits, it is important to be able to monitor the balance between cerebral oxygen demand and delivery in order to optimise cerebral perfusion during and immediately after cardiac arrest. Cerebral oximetry by near-infrared spectroscopy is a non-invasive optical monitoring method that measures regional cerebral oxygen saturation (rSO2) providing a real time indicator of the balance between cerebral oxygen demand and supply.3 A recent study at our centre focusing on patients who arrested on an inpatient floor after being admitted to the hospital has demonstrated that cerebral oximetry is feasible during inhospital cardiac arrest and does not interfere with resuscitative efforts.4 Patients with return of spontaneous circulation (ROSC) as well as survivors had significantly higher overall mean rSO2. However, the feasibility and role of cerebral oximetry in the Emergency Department (ED) has not yet been determined. In the current study we describe our experience with and the feasibility of real time noninvasive cerebral oximetry in ED patients with out-of-hospital SCA and explore the association between rSO2 and ROSC and survival in this study population.
Produced by BMJ Publishing Group Ltd under licence.
1
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article METHODS Study design We conducted a structured retrospective chart review of ED patients undergoing cardiopulmonary resuscitation (CPR) in our ED after out-of-hospital SCA in whom continuous cerebral oximetry was performed. Given the retrospective nature of our study the Institutional Review Board determined that the study was exempt from informed consent. We have previously incorporated cerebral oximetry into our clinical practice although use of cerebral oximetry is at the discretion of the attending physician.
Setting and patients The study was conducted in an academic, suburban ED with an affiliated residency programme in emergency medicine and an annual ED census of 90 000. Adult patients arriving in the ED with SCA in whom continuous cerebral oximetry was recorded during resuscitation were included in the study. Patients who arrived after ROSC were not included. In our institution manual CPR is initiated on patient arrival. In patients in whom cerebral oximetry readings remain below 50%, mechanical compressions are performed using a ‘Thumper’ device (Life Stat, Michigan Instruments, Michigan, USA).
Measures and outcomes Demographic and clinical data were collected using standardised data collection forms conforming to Utstein recommendations.5 The primary outcome of the study was ROSC. A secondary outcome was survival to hospital discharge.
Cerebral oximetry Cerebral oximetry was measured during cardiac arrest using noninvasive infrared spectroscopy (Equanox Nonin, Plymouth, Minnesota, USA). After arrival in the ED the patient was transferred to an ED gurney and CPR was continued by the ED staff. After replacement of cardiac pacing/defibrillation pads a cerebral oximetry sensor pad was placed on the patient’s forehead by an ED nurse or physician who was not performing CPR (figure 1) and monitoring was carried out continuously with the brain oximetry monitor until ROSC or CPR was terminated. With the oximetry device, emitted light is scattered by tissues in two parabolic curves, one corresponding to haemoglobin saturation from the skin and skull and the other from the skin, skull and frontal cortex.6 The haemoglobin saturation on the surface of the frontal cortex is calculated using specific computerised algorithms. For each resuscitation, the complete rSO2 data for each patient (sampled every 4 s) was taken from the time the sensor had been placed on the patient until either ROSC had been achieved or until CPR had been terminated. Artefact values were recognised by either an absent value or values that were at least three SDs away from the mean rSO2. This was used to calculate the mean rSO2 during the entire resuscitation period after arrival in the ED.
Data analysis Continuous data were summarised with means and SDs since mean rSO2 was approximately normally distributed. Binary data were summarised as the percentage frequency of occurrence. Mean rSO2 was compared between those with and without ROSC and between survivors and non-survivors using the t test. The receiver operating characteristic (ROC) characteristics of sensitivity, specificity, and positive and negative predictive values and the area under the curve (AUC) with 95% CI for mean rSO2 as a predictor of ROSC were also calculated. A sample size of 25 patients in each 2
Figure 1 Placement of a cerebral oximetry sensing pad on the patient’s forehead. group had 80% power to detect a 15% difference in the rSO2 between the groups with a statistically significant level of 0.05.
RESULTS Between January 2012 and July 2013 there were 59 patients who presented to the ED in cardiac arrest and had continuous cerebral oximetry readings (table 1). Their mean (SD) age was 68.7 (14.9) Table 1
Summary of patient characteristics.
Mean age (SD), years Men, No. (%) Location of cardiac arrest: outside of hospital, No. (%) Initial cardiac rhythm, No. (%) Pulseless electrical activity Asystole Ventricular fibrillation/tachycardia ROSC, No. (%) Survival to hospital discharge, No. (%)
68.7 (14.9) 50 (84.7) 59 (100) 21 20 17 24 1
(35.6) (33.9) (28.8) (40.6) (1.7)
ROSC, return of spontaneous circulation.
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article
Figure 2 Box plot of regional cerebral oxygen saturation (rSO2) by return of spontaneous circulation (ROSC).
ranging from 18 years to 102 years; 50 (84.7%) were men. Presenting rhythms included pulseless electrical activity (21), asystole (20) and ventricular fibrillation/tachycardia (17). Twenty-four patients (40.6%) had ROSC and only 1 (1.7%) survived to hospital discharge. Since all patients initially presented with cerebral oximetry readings below 50%, mechanical compressions were performed in all patients. Patients with and without ROSC were similar in age (68.0 years vs 69.2 years), per cent male (79.2% vs 88.6%) 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 (figure 2). Of patients with ROSC 91.7% had a rSO2 of 30% or greater compared with 62.9% in those without ROSC ( p=0.01). The ROC characteristics of rSO2 using a cut-off of 30% were 91.7% (sensitivity), 37.1% (specificity), 50% ( positive predictive value) and 86.7% (negative predictive value). The mean (95% CI) duration of the resuscitation was similar in those with and without ROSC (13 (8–19) min vs 19 (14–25) min respectively;
Figure 3 The area under the curve for mean regional cerebral oxygen saturation as a predictor of return of spontaneous circulation.
p=0.11). The AUC for mean rSO2 as a predictor of ROSC was 0.76 (95% CI 0.64 to 0.89) (figure 3). A representative monitor recording depicting the relationship between cerebral oximetry and ROSC is presented in figure 4.
DISCUSSION Our results demonstrate that continuous monitoring of cerebral oximetry using non-invasive infrared spectroscopy during CPR in ED patients presenting with out-of-hospital SCA is feasible and does not interfere with or interrupt resuscitative efforts. Placement of the brain oximetry sensor pad is similar to placement of a pulse oximetry pad. Our study also shows that ROSC is associated with higher mean rSO2 and that ROSC rarely occurs when rSO2 remains below 30%. Unfortunately, since only one of
Figure 4 Representative monitor recording of cerebral oxygenation in a patient with cardiac arrest. The sudden rise in regional cerebral oxygen saturation immediately preceded return of spontaneous circulation (ROSC).
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467
3
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article the patients in this series survived to hospital discharge we could not statistically assess the association between rSO2 and survival. Our results are in agreement with several prior studies investigating the use of cerebral oximetry in cardiac arrest. A small study on patients with out-of-hospital cardiac arrest found that all survivors had higher cerebral oxygenation readings than nonsurvivors (63% vs 46%, p=0.003).6 A study of 16 patients with out-of-hospital cardiac arrest found that all four subjects with ROSC had detectable cerebral oximetry readings while in those with no ROSC cerebral oximetry readings were undetectable.7 They concluded that standard CPR rarely provides detectable oxygenation of the brain. In our centre, the updated American Heart Association guidelines emphasising faster and deeper chest compressions, a lower number of ventilations and minimal interruptions in CPR are followed, likely leading to higher oximetry readings than those reported by Newman et al.7 In addition, we also incorporated mechanical compressions (Life Stat, Michigan Instruments, Michigan, USA) when cerebral oximetry readings remained low with notable improvements in cerebral oxygenation (not presented). In another study of 33 patients with out-of-hospital cardiac arrest all had readings below 15% and none survived.8 However a recent study by our group in 50 patients with inhospital cardiac arrests found that rSO2 may predict ROSC. Compared with those who did not achieve ROSC, patients with ROSC had significantly higher levels of mean rSO2 (47.2% ±10.7 vs 31.7±12.8%, p
EMJ Online First, published on March 24, 2014 as 10.1136/emermed-2013-203467 Original article
Cerebral oximetry levels during CPR are associated with return of spontaneous circulation following cardiac arrest: an observational study Adam J Singer, Anna Ahn, Loren A Inigo-Santiago, Henry C Thode Jr, Mark C Henry, Sam Parnia Resuscitation Research Group, Departments of Emergency Medicine and Medicine, Stony Brook University, Stony Brook, New York, USA Correspondence to Dr Adam J Singer, Department of Emergency Medicine, HSCL4-080, 8350 SUNY, Stony Brook, NY 11794-8350, USA; [email protected] Presented at the Annual Meeting of the Society for Academic Emergency Medicine, Atlanta, GA, May 2013. Received 2 December 2013 Revised 24 January 2014 Accepted 1 February 2014
ABSTRACT 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.
INTRODUCTION
To cite: Singer AJ, Ahn A, Inigo-Santiago LA, et al. Emerg Med J Published Online First: [ please include Day Month Year] doi:10.1136/emermed-2013203467
Each year there are over 350 000 deaths from sudden cardiac arrest (SCA) in the USA alone, which is more than the total number of deaths from Alzheimer’s’ disease, assault with firearms, breast cancer, cervical cancer, colorectal cancer, diabetes, HIV, house fires, motor vehicle accidents, prostate cancer and suicides combined.1 Despite major advances in the understanding of SCA mortality remains high with less than 1 of 10 victims of out-of-hospital SCA surviving to hospital discharge.2 Even among survivors, many are left with significant neurological and cognitive deficits.
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467 Copyright Article author (or their employer) 2014.
Key messages What is already known on this subject? Survival from cardiac arrest is poor and dependent on adequate perfusion of the heart and brain. Currently there are few objective guides for monitoring and optimizing cerebral perfusion in cardiac arrest. What this study adds? This study demonstrates that it is feasible to continuously monitor cerebral oxygenation and perfusion during resuscitation. It also demonstrates an association between improved cerebral oxygenation and return of spontaneous circulation in emergency department patients presenting after out-ofhospital cardiac arrest. Optimization of resuscitation and improved outcomes may be guided by cerebral oximetry.
In order to maximise the effectiveness of cardiopulmonary resuscitation and increase the likelihood that victims of SCA will survive without major neurological deficits, it is important to be able to monitor the balance between cerebral oxygen demand and delivery in order to optimise cerebral perfusion during and immediately after cardiac arrest. Cerebral oximetry by near-infrared spectroscopy is a non-invasive optical monitoring method that measures regional cerebral oxygen saturation (rSO2) providing a real time indicator of the balance between cerebral oxygen demand and supply.3 A recent study at our centre focusing on patients who arrested on an inpatient floor after being admitted to the hospital has demonstrated that cerebral oximetry is feasible during inhospital cardiac arrest and does not interfere with resuscitative efforts.4 Patients with return of spontaneous circulation (ROSC) as well as survivors had significantly higher overall mean rSO2. However, the feasibility and role of cerebral oximetry in the Emergency Department (ED) has not yet been determined. In the current study we describe our experience with and the feasibility of real time noninvasive cerebral oximetry in ED patients with out-of-hospital SCA and explore the association between rSO2 and ROSC and survival in this study population.
Produced by BMJ Publishing Group Ltd under licence.
1
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article METHODS Study design We conducted a structured retrospective chart review of ED patients undergoing cardiopulmonary resuscitation (CPR) in our ED after out-of-hospital SCA in whom continuous cerebral oximetry was performed. Given the retrospective nature of our study the Institutional Review Board determined that the study was exempt from informed consent. We have previously incorporated cerebral oximetry into our clinical practice although use of cerebral oximetry is at the discretion of the attending physician.
Setting and patients The study was conducted in an academic, suburban ED with an affiliated residency programme in emergency medicine and an annual ED census of 90 000. Adult patients arriving in the ED with SCA in whom continuous cerebral oximetry was recorded during resuscitation were included in the study. Patients who arrived after ROSC were not included. In our institution manual CPR is initiated on patient arrival. In patients in whom cerebral oximetry readings remain below 50%, mechanical compressions are performed using a ‘Thumper’ device (Life Stat, Michigan Instruments, Michigan, USA).
Measures and outcomes Demographic and clinical data were collected using standardised data collection forms conforming to Utstein recommendations.5 The primary outcome of the study was ROSC. A secondary outcome was survival to hospital discharge.
Cerebral oximetry Cerebral oximetry was measured during cardiac arrest using noninvasive infrared spectroscopy (Equanox Nonin, Plymouth, Minnesota, USA). After arrival in the ED the patient was transferred to an ED gurney and CPR was continued by the ED staff. After replacement of cardiac pacing/defibrillation pads a cerebral oximetry sensor pad was placed on the patient’s forehead by an ED nurse or physician who was not performing CPR (figure 1) and monitoring was carried out continuously with the brain oximetry monitor until ROSC or CPR was terminated. With the oximetry device, emitted light is scattered by tissues in two parabolic curves, one corresponding to haemoglobin saturation from the skin and skull and the other from the skin, skull and frontal cortex.6 The haemoglobin saturation on the surface of the frontal cortex is calculated using specific computerised algorithms. For each resuscitation, the complete rSO2 data for each patient (sampled every 4 s) was taken from the time the sensor had been placed on the patient until either ROSC had been achieved or until CPR had been terminated. Artefact values were recognised by either an absent value or values that were at least three SDs away from the mean rSO2. This was used to calculate the mean rSO2 during the entire resuscitation period after arrival in the ED.
Data analysis Continuous data were summarised with means and SDs since mean rSO2 was approximately normally distributed. Binary data were summarised as the percentage frequency of occurrence. Mean rSO2 was compared between those with and without ROSC and between survivors and non-survivors using the t test. The receiver operating characteristic (ROC) characteristics of sensitivity, specificity, and positive and negative predictive values and the area under the curve (AUC) with 95% CI for mean rSO2 as a predictor of ROSC were also calculated. A sample size of 25 patients in each 2
Figure 1 Placement of a cerebral oximetry sensing pad on the patient’s forehead. group had 80% power to detect a 15% difference in the rSO2 between the groups with a statistically significant level of 0.05.
RESULTS Between January 2012 and July 2013 there were 59 patients who presented to the ED in cardiac arrest and had continuous cerebral oximetry readings (table 1). Their mean (SD) age was 68.7 (14.9) Table 1
Summary of patient characteristics.
Mean age (SD), years Men, No. (%) Location of cardiac arrest: outside of hospital, No. (%) Initial cardiac rhythm, No. (%) Pulseless electrical activity Asystole Ventricular fibrillation/tachycardia ROSC, No. (%) Survival to hospital discharge, No. (%)
68.7 (14.9) 50 (84.7) 59 (100) 21 20 17 24 1
(35.6) (33.9) (28.8) (40.6) (1.7)
ROSC, return of spontaneous circulation.
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article
Figure 2 Box plot of regional cerebral oxygen saturation (rSO2) by return of spontaneous circulation (ROSC).
ranging from 18 years to 102 years; 50 (84.7%) were men. Presenting rhythms included pulseless electrical activity (21), asystole (20) and ventricular fibrillation/tachycardia (17). Twenty-four patients (40.6%) had ROSC and only 1 (1.7%) survived to hospital discharge. Since all patients initially presented with cerebral oximetry readings below 50%, mechanical compressions were performed in all patients. Patients with and without ROSC were similar in age (68.0 years vs 69.2 years), per cent male (79.2% vs 88.6%) 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 (figure 2). Of patients with ROSC 91.7% had a rSO2 of 30% or greater compared with 62.9% in those without ROSC ( p=0.01). The ROC characteristics of rSO2 using a cut-off of 30% were 91.7% (sensitivity), 37.1% (specificity), 50% ( positive predictive value) and 86.7% (negative predictive value). The mean (95% CI) duration of the resuscitation was similar in those with and without ROSC (13 (8–19) min vs 19 (14–25) min respectively;
Figure 3 The area under the curve for mean regional cerebral oxygen saturation as a predictor of return of spontaneous circulation.
p=0.11). The AUC for mean rSO2 as a predictor of ROSC was 0.76 (95% CI 0.64 to 0.89) (figure 3). A representative monitor recording depicting the relationship between cerebral oximetry and ROSC is presented in figure 4.
DISCUSSION Our results demonstrate that continuous monitoring of cerebral oximetry using non-invasive infrared spectroscopy during CPR in ED patients presenting with out-of-hospital SCA is feasible and does not interfere with or interrupt resuscitative efforts. Placement of the brain oximetry sensor pad is similar to placement of a pulse oximetry pad. Our study also shows that ROSC is associated with higher mean rSO2 and that ROSC rarely occurs when rSO2 remains below 30%. Unfortunately, since only one of
Figure 4 Representative monitor recording of cerebral oxygenation in a patient with cardiac arrest. The sudden rise in regional cerebral oxygen saturation immediately preceded return of spontaneous circulation (ROSC).
Singer AJ, et al. Emerg Med J 2014;0:1–4. doi:10.1136/emermed-2013-203467
3
Downloaded from http://emj.bmj.com/ on November 12, 2014 - Published by group.bmj.com
Original article the patients in this series survived to hospital discharge we could not statistically assess the association between rSO2 and survival. Our results are in agreement with several prior studies investigating the use of cerebral oximetry in cardiac arrest. A small study on patients with out-of-hospital cardiac arrest found that all survivors had higher cerebral oxygenation readings than nonsurvivors (63% vs 46%, p=0.003).6 A study of 16 patients with out-of-hospital cardiac arrest found that all four subjects with ROSC had detectable cerebral oximetry readings while in those with no ROSC cerebral oximetry readings were undetectable.7 They concluded that standard CPR rarely provides detectable oxygenation of the brain. In our centre, the updated American Heart Association guidelines emphasising faster and deeper chest compressions, a lower number of ventilations and minimal interruptions in CPR are followed, likely leading to higher oximetry readings than those reported by Newman et al.7 In addition, we also incorporated mechanical compressions (Life Stat, Michigan Instruments, Michigan, USA) when cerebral oximetry readings remained low with notable improvements in cerebral oxygenation (not presented). In another study of 33 patients with out-of-hospital cardiac arrest all had readings below 15% and none survived.8 However a recent study by our group in 50 patients with inhospital cardiac arrests found that rSO2 may predict ROSC. Compared with those who did not achieve ROSC, patients with ROSC had significantly higher levels of mean rSO2 (47.2% ±10.7 vs 31.7±12.8%, p
