Improving the neurological prognosis following OHCA using real-time evaluation of cerebral tissue oxygenation

Background

The neurological prognosis is poor for patients suffering from out-of-hospital cardiac arrest (OHCA), in the absence of bystander cardio pulmonary resuscitation (CPR), and showing asystole as the initial waveform. However, such patients have the potential of resuming social activity if cerebral tissue oxygen saturation can be preserved.

Compression-only cardiopulmonary resuscitation vs standard cardiopulmonary resuscitation: an updated meta-analysis of observational studies

Objectives

To perform an updated meta-analysis of observational studies with unstratified cohort addressing whether compression-only cardiopulmonary resuscitation (CPR), compared with standard CPR, improves outcomes in adult patients with out-of-hospital cardiac arrest and a subgroup meta-analysis for the patients with cardiac etiology arrest.

Methods

We searched the relevant literature from MEDLINE and EMBASE databases. The baseline information and outcome data (survival to hospital discharge, favorable neurologic outcome at hospital discharge, and return of spontaneous circulation on hospital arrival) were extracted both in an out-of-hospital cardiac arrest and cardiac origin arrest subgroup. Meta-analyses were performed by using Review Manager 5.0.

Results

Eight studies involving 92?033 patients were eligible. Overall meta-analysis showed that standard CPR was associated with statistically improved survival to hospital discharge (risk ratio [RR], 0.95 [95% confidence interval, 0.91-0.99]) and return of spontaneous circulation on hospital arrival (RR, 0.95 [95% confidence interval, 0.92-0.99]) compared with compression-only CPR, but there is no significant difference in favorable neurologic outcome at hospital discharge between 2 CPR methods (RR, 0.97 [95% confidence interval, 0.91-1.04]). In the subgroup of patients with a cardiac cause of arrest, the pooled meta-analysis found compression-only CPR resulted in the similar survival to hospital discharge as standard CPR (RR, 0.99 [95% confidence interval, 0.94-1.05]).

Conclusions

This meta-analysis found that compression-only CPR resulted in the similar survival rate as the standard CPR in the cardiac etiology subgroup. It is unclear for the patients with noncardiac cause of arrest and with long periods of untreated arrest.     

Feasibility of absolute cerebral tissue oxygen saturation during cardiopulmonary resuscitation

Introduction

Current monitoring during cardiopulmonary resuscitation (CPR) is limited to clinical observation of consciousness, breathing pattern and presence of a pulse. At the same time, the adequacy of cerebral oxygenation during CPR is critical for neurological outcome and thus survival. Cerebral oximetry, based on near-infrared spectroscopy (NIRS), provides a measure of brain oxygen saturation. Therefore, we examined the feasibility of using NIRS during CPR.

Methods

Recent technologies (FORE-SIGHT™ and EQUANOX™) enable the monitoring of absolute cerebral tissue oxygen saturation (SctO₂) values without the need for pre-calibration. We tested both FORE-SIGHT™ (five patients) and EQUANOX Advance™ (nine patients) technologies in the in-hospital as well as the out-of-hospital CPR setting. In this observational study, values were not utilized in any treatment protocol or therapeutic decision. An independent t-test was used for statistical analysis.

Results

Our data demonstrate the feasibility of both technologies to measure cerebral oxygen saturation during CPR. With the continuous, pulseless near-infrared wave analysis of both FORE-SIGHT™ and EQUANOX™ technology, we obtained SctO₂ values in the absence of spontaneous circulation. Both technologies were able to assess the efficacy of CPR efforts: improved resuscitation efforts (improved quality of chest compressions with switch of caregivers) resulted in higher SctO₂ values. Until now, the ability of CPR to provide adequate tissue oxygenation was difficult to quantify or to assess clinically due to a lack of specific technology. With both technologies, any change in hemodynamics (for example, ventricular fibrillation) results in a reciprocal change in SctO₂. In some patients, a sudden drop in SctO₂ was the first warning sign of reoccurring ventricular fibrillation.

Conclusions

Both the FORE-SIGHT™ and EQUANOX™ technology allow non-invasive monitoring of the cerebral oxygen saturation during CPR. Moreover, changes in SctO₂ values might be used to monitor the efficacy of CPR efforts.     

Bispectral index monitoring is useless during cardiac arrest patients’ resuscitation

Aim

It has been suggested that out-of-hospital bispectral (BIS) index monitoring during advanced cardiac life support (ACLS) might provide an indication of cerebral resuscitation. The aims of our study were to establish whether BIS values during ACLS might predict return to spontaneous circulation, and whether BIS values on hospital admission might predict survival.

Materials and methods

This was a prospective observational study in 92 patients with cardiac arrest who received basic life support from a fire-fighter squad and ACLS on arrival of an emergency medical team on the scene. BIS values, electromyographic activity, and signal quality index were recorded throughout resuscitation and out-of-hospital management.

Results

Seven patients had recovered spontaneous cardiac activity by the time the medical team arrived on scene. Of the 92 patients, 62 patients died on scene and 30 patients returned to spontaneous cardiac activity and were admitted to hospital. The correlation between BIS values and end-tidal CO₂ during the first minutes of ACLS was poor (r² = 0.02, P = 0.19). Of the 30 admitted patients, 27 died. Three were discharged with no disabilities. There was no significant difference in BIS values on admission between the group of patients who died and the group who survived (P = 0.78).

Conclusions

Although BIS monitoring during resuscitation was not difficult, it did not predict return to spontaneous cardiac activity, nor survival after admission to intensive care. Its use to monitor cerebral function during ACLS is therefore pointless.     

Factors associated with sustained return of spontaneous circulation in children after out-of-hospital cardiac arrest of noncardiac origin

Purpose

The study aimed to determine the factors predictive of sustained return of spontaneous circulation (ROSC) in children with out-of-hospital cardiac arrest (OHCA) of noncardiac origin.

Methods

Eighty children were included in this retrospective study. The variables that lead to sustained ROSC and those that do not lead to sustained ROSC were analyzed. Survival analyses, including chance of achieving sustained ROSC and sum duration of ROSC, were conducted according to the duration of in-hospital cardiopulmonary resuscitation (CPR).

Results

Etiologies of noncardiac OHCA differed significantly across different age groups (P < .001). Only 8.8% of children had initial arrest rhythms that were shockable. Predictors of sustained ROSC included the initial cardiac rhythm (P = .002), a shorter period between collapse and the first chest compression (P = .002), a shorter in-hospital CPR duration (P = .004), and prehospital CPR (P = .007). In children where ROSC was initially sustained, those with in-hospital CPR of more than 20 minutes, ROSC was sustained for less time (P < .001).

Conclusions

Few children with noncardiac OHCA present with shockable cardiac rhythms. Furthermore, long-term ROSC is difficult to maintain in children who receive in-hospital CPR for more than 20 minutes.     

Exploring which patients without return of spontaneous circulation following ventricular fibrillation out-of-hospital cardiac arrest should be transported to hospital?

Background

Currently many emergency medical services (EMS) that provide advanced cardiac life support (ACLS) at scene do not routinely transport out-of-hospital cardiac arrest (OHCA) patients without sustained return of spontaneous circulation (ROSC). This is due to logistical difficulties and historical poor outcomes. However, new technology for mechanical chest compression has made transport to hospital safer and extracorporeal membrane oxygenation during cardiopulmonary resuscitation (ECPR) enabling further intervention, may result in ROSC. We aimed to explore the characteristics and outcomes of patients with OHCA who were transported to hospital with ongoing CPR in the absence of ROSC, who might benefit from this new technology.

Methods and results

The Victorian Ambulance Cardiac Arrest Registry (VACAR) was searched for adult OHCA with an initial shockable rhythm between 2003 and 2012. There were 5593 OHCA meeting inclusion criteria. Analysis was performed on 3095 (55%) of patients who did not achieve sustained ROSC in the field. Of these only 589 (20%) had ongoing CPR to hospital. There was a significant decline in rates of transport over the study period. Predictors of transport with ongoing CPR included younger patients, decreased time to first shock and intermittent ROSC prior to transport. Survival to hospital discharge occurred in 52 (9%) of patients who had ongoing CPR to hospital.

Conclusion

In an EMS that provides ACLS at scene, patients without ROSC in the field who receive CPR to hospital have poor outcomes. Developing a system which provides safe transport with ongoing CPR to a hospital that provides ECPR, should be considered.     

A national resuscitation registry of out-of-hospital cardiac arrest in Germany—A pilot study

Background

Survival rate after out-of-hospital cardiac arrest (OHCA) has not significantly increased over the last decade. However, survival rate has been used as a quality benchmark for many emergency medical services. A uniform resuscitation registry may be advantageous for quality management of cardiopulmonary resuscitation (CPR). This study was conducted to evaluate the establishment of a national CPR registry in Germany.

Materials and methods

A prospective cohort study was performed that included 469 patients who experienced OHCA requiring CPR in the metropolitan area of Dortmund, Germany. Cardiac arrest was defined as concomitant appearance of unconsciousness, apnoea or gasping and pulselessness. All data were collected via a secure and confidential paper-based method as the data set ‘Preclinical care’.

Results

Quality of data was classified as ‘good’ in 33.4%, ‘moderate’ in 48.4%, and ‘bad’ in 18.2% of the patients, respectively. Sixty-two percent had OHCA in private residences, 24% of the patients had a first monitored rhythm of ventricular fibrillation (VF) or ventricular tachycardia (VT), 35.2% had return of spontaneous circulation (ROSC) on scene, and patients presenting VF/VT as the first monitored rhythm had higher ROSC rates (51.3%) compared to patients with asystole (22.6%).

Conclusion

The data set ‘Preclinical care’ proved to be congruent with the Utstein style, provided further information for national and international comparisons, and enabled a detailed analysis. Optimisation of data collection and introduction of strict control mechanisms may further improve data quality.     

Adult Out-of-Hospital Cardiac Arrest Based on Chain of Survival in Taoyuan County,Northern Taiwan

Background

Most out-of-hospital cardiac arrest (OHCA) studies have been conducted in developed countries or metropolitan areas, and few in developing countries or rural areas.

Objectives

The aims of this study were to determine the weak links in the chain of survival and to estimate the outcomes of OHCA patients in Taoyuan, a nonmetropolitan area in Taiwan.

Methods

A retrospective review and analysis of OHCA data was conducted. The three outcomes were whether a return of spontaneous circulation (ROSC) was achieved, whether the patient survived to admission, or whether the patient survived to hospital discharge.

Results

From April to December 2008, 1048 OHCA patients were resuscitated, and 712 (67.9%) adult cardiac patients were used in this study. Among these 712 patients, 17.8% achieved ROSC (95% confidence interval [CI] 15.2–20.8%), 16.3% survived to admission (95% CI 13.6–19.0%), and 1.4% survived to discharge (95% CI 0.5–2.3%). Factors significantly associated with the three outcomes were witness status, response time to emergency medical services, and whether the patient had a shockable rhythm. Bystander cardiopulmonary resuscitation (CPR) did not add a notable benefit to the outcomes of OHCA.

Conclusions

The survival rate of OHCA patients in nonmetropolitan Taiwan was very low (1.4%). Lower witnessed rate, lower bystander CPR rate, and longer response interval in remote areas are the main causes of inferior survival rate.     

3:1 Compression to ventilation ratio versus continuous chest compression with asynchronous ventilation in a porcine model of neonatal resuscitation

Objective

In contrast to the resuscitation guidelines of children and adults, guidelines on neonatal resuscitation recommend synchronized 90 chest compressions with 30 manual inflations (3:1) per minute in newborn infants. The study aimed to determine if chest compression with asynchronous ventilation improves the recovery of bradycardic asphyxiated newborn piglets compared to 3:1 Compression:Ventilation cardiopulmonary resuscitation (CPR).

Intervention and measurements

Term newborn piglets (n = 8/group) were anesthetized, intubated, instrumented and exposed to 45-min normocapnic hypoxia followed by asphyxia. Protocolized resuscitation was initiated when heart rate decreased to 25% of baseline. Piglets were randomized to receive resuscitation with either 3:1 compressions to ventilations (3:1 C:V CPR group) or chest compressions with asynchronous ventilations (CCaV) or sham. Continuous respiratory parameters (Respironics NM3^®), cardiac output, mean systemic and pulmonary artery pressures, and regional blood flows were measured.

Main results

Piglets in 3:1 C:V CPR and CCaV CPR groups had similar time to return of spontaneous circulation, survival rates, hemodynamic and respiratory parameters during CPR. The systemic and regional hemodynamic recovery in the subsequent 4 h was similar in both groups and significantly lower compared to sham-operated piglets.

Conclusion

Newborn piglets resuscitated by CCaV had similar return of spontaneous circulation, survival, and hemodynamic recovery compared to those piglets resuscitated by 3:1 Compression:Ventilation ratio.     

Duplex sonography of cerebral blood flow after cardiac arrest—A prospective observational study

Aim

Despite successful resuscitation, cardiac arrest (CA) often has a poor clinical prognosis. Different diagnostic tools have been established to predict patients’ outcome. However, their sensitivity remains low. Assessment of cerebral perfusion by duplex ultrasound might provide additional information regarding the extent of neuronal damage. The aim of the present study was to analyse the changes of global cerebral blood flow (CBF) and intracranial blood flow parameters in the acute stage after CA and its correlation with patients’ outcome.

Methods

We investigated 54 patients (17–85 years, mean age: 63 ± 17 years) after CA with return of spontaneous circulation on an intensive care unit. All patients received therapeutic hypothermia (TH) for 24 h after CA and reanimation. Serial measurements of CBF as well as intracranial blood flow velocities and pulsatility indices of the middle cerebral artery and the basal vein of Rosenthal were performed within the first 10 days using duplex ultrasound. Clinical outcome was measured using the Cerebral Performance Category.

Results

Measurements were successful in 53 patients. CBF values differed between 210 and 1100 ml/min. 24 patients (45%) attained a good outcome. No correlation between CBF or intracranial blood flow characteristics and outcome was found. Neither cerebral hypo- nor hyperperfusion was associated with a fatal outcome.

Conclusion

Cerebral perfusion varies widely after CA. Neither hypo- nor hyperperfusion seems to be an independent risk factor for poor outcome. Duplex ultrasound of cerebral haemodynamics after CA is suitable but probably of limited prognostic value.     

The relationship between chest compression fraction and outcome from ventricular fibrillation arrests in prolonged resuscitations

Background

Guidelines direct rescuers to minimize CPR interruptions during resuscitation. There is little evidence that evaluates the relationship of increasing CPR fraction among patients with relatively high fractions or prolonged resuscitation.

Methods

We conducted an observational study of persons who suffered out-of-hospital ventricular fibrillation arrest and required >5 min of emergency medical services (EMS) CPR for persistent pulselessness. We determined the association between hands-on CPR fraction and outcomes of spontaneous circulation, survival to hospital discharge, and neurologically favorable survival. Analyses were stratified by median hands-on CPR and were conducted for those who required 5, 10, and 20 min of EMS CPR for persistent pulselessness.

Results

Of 414 potentially eligible patients, 323 (78%) required >5 min of EMS CPR, 234 (56%) required >10 min of EMS CPR, and 153 (37%) required EMS CPR for >20 min. The median CPR fraction was 81%. We did not observe a significant association for the outcomes of hospital survival and neurologically favorable survival for the 5-min and 10-min groups. When restricted to patients who required >20 min of EMS CPR, the half who received a higher hands-on CPR fraction were more likely to achieve spontaneous circulation (40% versus 18%, p = 0.004), survival to hospital discharge (20% versus 8%, p = 0.03), and neurologically favorable survival (20% versus 7%, p = 0.02).

Conclusion

Over one-third required 20 min of persistent EMS CPR. The EMS was able to achieve a high hands-on CPR fraction in the context of advanced therapies. Those who required the most prolonged EMS CPR appeared to benefit from greater hands-on CPR fraction.     

Regional cerebral oxygen saturation after cardiac arrest in 60 patients—A prospective outcome study

Introduction

Non-invasive near-infrared spectroscopy (NIRS) offers the possibility to determine regional cerebral oxygen saturation (rSO₂) in patients with cardiac arrest. Limited data from recent studies indicate a potential for early prediction of neurological outcome.

Methods

Sixty cardiac arrest patients were prospectively enrolled, 22 in-hospital cardiac arrest (IHCA) and 38 out-of-hospital cardiac arrest (OHCA) patients respectively. NIRS of frontal brain was started after return of spontaneous circulation (ROSC) during admission to ICU and was continued until normothermia. Outcome was determined at ICU discharge by the Pittsburgh Cerebral Performance Category (CPC) and 6 months after cardiac arrest.

Results

A good outcome (CPC 1–2) was achieved in 23 (38%) patients, while 37 (62%) had a poor outcome (CPC 3–5). Patients with good outcome had significantly higher rSO₂ levels (CPC 1–2: rSO₂ 68%; CPC 3–5: rSO₂ 58%; p < 0.01). For good and poor outcome median rSO₂ within the first 24 h period was 66% and 59% respectively and for the following 16 h period 68% and 59% (p < 0.01). Outcome prediction by area of rSO₂ below a critical threshold of rsO₂ = 50% within the first 40 h yielded 70% specificity and 86% sensitivity for poor outcome.

Conclusion

On average, rSO₂ within the first 40 h after ROSC is significantly lower in patients with poor outcome, but rSO₂ ranges largely overlap between outcome groups. Our data indicate limited potential for prediction of poor outcome by frontal brain rSO₂ measurements.     

Electroencephalography during Out-of-hospital Cardiopulmonary Resuscitation

Background

At the present time there is no parameter that can estimate the quality of cerebral perfusion and possible success of cerebral resuscitation during advanced cardiac life support (ACLS) efforts. In recent years, various attempts have been made to use electroencephalography (EEG)-based cerebral neuromonitoring to assess the effectiveness of cardiopulmonary resuscitation (CPR).

Objectives

The Cerebral State Monitor M3 (Danmeter A/S, Odense, Denmark) is a portable, single-channel EEG monitor that provides the user with different EEG-based parameters and the raw waveform EEG to measure cerebral activity.

Case Report

We report two cases of out-of-hospital CPR with single-channel EEG monitoring conducted parallel to ACLS with external chest compressions. We demonstrate an artifact in waveform EEG recordings that is caused by the external chest compressions, and that leads to a miscalculation of the Burst Suppression Ratio and Cerebral State Index.

Conclusion

These cases suggest that digitally processed EEG-monitoring is not a useful tool during CPR.     

Cerebral metabolic rate of oxygen (CMRO2) in pig brain determined by PET after resuscitation from cardiac arrest

Aim

To assess the regional vulnerability to ischemic damage and perfusion/metabolism mismatch of reperfused brain following restoration of spontaneous circulation (ROSC) after cardiac arrest.

Method

We used positron emission tomography (PET) to map cerebral metabolic rate of oxygen (CMRO₂), cerebral blood flow (CBF) and oxygen extraction fraction (OEF) in brain of young pigs at intervals after resuscitation from cardiac arrest. After obtaining baseline PET recordings, ventricular fibrillation of 10 min duration was induced, followed by mechanical closed-chest cardiopulmonary resuscitation (CPR) in conjunction with i.v. administration of 0.4 U/kg of vasopressin. After CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). CBF and CMRO₂ were mapped and voxelwise maps of OEF were calculated at times of 60, 180, and 300 min after ROSC.

Results

There was hypoperfusion throughout the telencephalon at 60 min, with a return towards baseline values at 300 min. In contrast, there was progressively increasing CBF in cerebellum throughout the observation period. The magnitude of CMRO₂ decreased globally after ROSC, especially in cerebral cortex. The magnitude of OEF in cerebral cortex was 60% at baseline, tended to increase at 60 min after ROSC, and declined to 50% thereafter, thus suggesting transition to an ischemic state.

Conclusion

The cortical regions tended most vulnerable to the ischemic insult with an oligaemic pattern and a low CMRO₂ whereas the cerebellum instead showed a pattern of luxury perfusion.     

Outcomes following cardiopulmonary resuscitation in an emergency department of a low- and middle-income country

Background

Cardiopulmonary resuscitation (CPR) is a key component of emergency care following cardiac arrest. A better understanding of factors that influence CPR outcomes and their prognostic implications would help guide care. A retrospective analysis of 800 adult patients that sustained an in- or out-of-hospital cardiac arrest and underwent CPR in the emergency department of a tertiary care facility in Karachi, Pakistan, between 2008 and 15 was conducted.

Methods

Patient demographics, clinical history, and CPR characteristics data were collected. Logistic regression model was applied to assess predictors of return of spontaneous circulation and survival to discharge. Analysis was conducted using SPSS v.21.0.

Results

Four hundred sixty-eight patients met the study’s inclusion criteria, and overall return of spontaneous circulation and survival to discharge were achieved in 128 (27.4%) and 35 (7.5%) patients respectively. Mean age of patients sustaining return of spontaneous circulation was 52 years and that of survival to discharge was 49 years. The independent predictors of return of spontaneous circulation included age ≤?49 years, witnessed arrest, ≤?30 min interval between collapse-to-start, and 1–4 shocks given during CPR (aOR (95% CI) 2.2 (1.3–3.6), 1.9 (1.0–3.7), 14.6 (4.9–43.4), and 3.0 (1.4–6.4) respectively), whereas, age ≤?52 years, bystander resuscitation, and initial rhythm documented (pulseless electrical activity and ventricular fibrillation) were independent predictors of survival to discharge (aOR (95% CI) 2.5 (0.9–6.5), 1.4 (0.5–3.8), 5.3 (1.5–18.4), and 3.1 (1.0–10.2) respectively).

Conclusion

Our study notes that while the majority of arrests occur out of the hospital, only a small proportion of those arrests receive on-site CPR, which is a key contributor to unfavorable outcomes in this group. It is recommended that effective pre-hospital emergency care systems be established in developing countries which could potentially improve post-arrest outcomes. Younger patients, CPR initiation soon after arrest, presenting rhythm of pulseless ventricular tachycardia and ventricular fibrillation, and those requiring up to four shocks to revive are more likely to achieve favorable outcomes.

     

Prearrest signs of shock and respiratory insufficiency in out-of-hospital cardiac arrests witnessed by crew of the emergency medical service

Aim

The objective of this study is to determine whether prearrest shock and respiratory insufficiency influence outcome in patients with emergency medical service–witnessed out-of-hospital cardiac arrest.

Methods

Analysis of data from a cardiac arrest database and data from the ambulance charts was performed. For the purpose of the study, shock was defined as prearrest heart rate below 40 or above 140/min, systolic blood pressure as below 90 mm Hg, and respiratory insufficiency as respiratory rate above 36 or oxygen saturation below 90%. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

Results

Of a total of 303 patients, 81% had prearrest shock or respiratory insufficiency. Mortality was higher in these patients indicated by fewer with return of spontaneous circulation (43% vs 75%, P < .001), and lower survival to hospital admission (31% vs 71%, P < .001) and to discharge (13% vs 59%, P < .001). Independent predictors of mortality were age (OR, 1.04; CI, 1.0-1.06), initial rhythm other than ventricular fibrillation or ventricular tachycardia (OR, 32.9; CI, 10.9-99.0), and respiratory insufficiency (OR, 4.2; CI, 1.4-12.5).

Conclusions

Shock and respiratory depression are common among patients with out-of-hospital cardiac arrest witnessed by the emergency medical service, and these patients have a high mortality when compared with patients without shock or respiratory failure.     

Increasing arterial oxygen partial pressure during cardiopulmonary resuscitation is associated with improved rates of hospital admission

Aim

As recent clinical data suggest a harmful effect of arterial hyperoxia on patients after resuscitation from cardiac arrest (CA), we aimed to investigate this association during cardiopulmonary resuscitation (CPR), the earliest and one of the most crucial phases of recirculation.

Methods

We analysed 1015 patients who from 2003 to 2010 underwent out-of-hospital CPR administered by emergency medical services serving 300,000 inhabitants. Inclusion criteria for further analysis were nontraumatic background of CA and patients >18 years of age. One hundred and forty-five arterial blood gas analyses including oxygen partial pressure (paO2) measurement were obtained during CPR.

Results

We observed a highly significant increase in hospital admission rates associated with increases in paO2 in steps of 100 mmHg (13.3 kPa).Subsequently, data were clustered according to previously described cutoffs (≤60 mmHg [8 kPa]], 61–300 mmHg [8.1–40 kPa], >300 mmHg [>40 kPa]). Baseline variables (age, sex, initial rhythm, rate of bystander CPR and collapse-to-CPR time) of the three compared groups did not differ significantly. Rates of hospital admission after CA were 18.8%, 50.6% and 83.3%, respectively. In a multivariate analysis, logistic regression revealed significant prognostic value for paO2 and the duration of CPR.

Conclusion

This study presents novel human data on the arterial paO2 during CPR in conjunction with the rate of hospital admission. We describe a significantly increased rate of hospital admission associated with increasing paO2. We found that the previously described potentially harmful effects of hyperoxia after return of spontaneous circulation were not reproduced for paO2 measured during CPR.Clinical trial registration: n/a.     

Factors complicating interpretation of capnography during advanced life support in cardiac arrest--a clinical retrospective study in 575 patients

Background

End tidal carbon dioxide (ETCO₂) monitoring during advanced life support (ALS) using capnography, is recommended in the latest international guidelines. However, several factors might complicate capnography interpretation during ALS. How the cause of cardiac arrest, initial rhythm, bystander cardiopulmonary resuscitation (CPR) and time impact on the ETCO₂ values are not completely clear. Thus, we wanted to explore this in out-of-hospital cardiac arrested (OHCA) patients.

Methods

The study was carried out by the Emergency Medical Service of Haukeland University Hospital, Bergen, Norway. All non-traumatic OHCAs treated by our service between January 2004 and December 2009 were included. Capnography was routinely used in the study, and these data were retrospectively reviewed together with Utstein data and other clinical information.

Results

Our service treated 918 OHCA patients, and capnography data were present in 575 patients. Capnography distinguished well between patients with or without return of spontaneous circulation (ROSC) for any initial rhythm and cause of the arrest (p < 0.001). Cardiac arrests with a respiratory cause had significantly higher levels of ETCO₂ compared to primary cardiac causes (p < 0.001). Bystander CPR affected ETCO₂-recordings, and the ETCO₂ levels declined with time.

Conclusions

Capnography is a useful tool to optimise and individualise ALS in cardiac arrested patients. Confounding factors including cause of cardiac arrest, initial rhythm, bystander CPR and time from cardiac arrest until quantitative capnography had an impact on the ETCO₂ values, thereby complicating and limiting prognostic interpretation of capnography during ALS.     

Predicting the lack of ROSC during pre-hospital CPR: Should an end-tidal CO2 of 1.3 kPa be used as a cut-off value?

Aim

The aim of this study was to investigate if an initial ETCO₂ value at or below 1.3 kPa can be used as a cut-off value for whether return of spontaneous circulation during pre-hospital cardio-pulmonary resuscitation is achievable or not.

Materials and methods

We prospectively registered data according to the Utstein-style template for reporting data from pre-hospital advanced airway management from February 1st 2011 to October 31st 2012. Included were consecutive patients at all ages with pre-hospital cardiac arrest treated by eight anaesthesiologist-staffed pre-hospital critical care teams in the Central Denmark Region.

Results

We registered data from 595 cardiac arrest patients; in 60.2% (n = 358) of these cases the pre-hospital critical care teams performed pre-hospital advanced airway management beyond bag-mask ventilation. An initial end-tidal CO₂ measurement following pre-hospital advanced airway management were available in 75.7% (n = 271) of these 358 cases. We identified 22 patients, who had an initial end-tidal CO₂ at or below 1.3 kPa. Four of these patients achieved return of spontaneous circulation.

Conclusion

Our results indicates that an initial end-tidal CO₂ at or below 1.3 kPa during pre-hospital CPR should not be used as a cut-off value for the achievability of return of spontaneous circulation.