The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation: difference between asphyxial cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest

Cardiopulmonary Resuscitation Without Aortic Valve Compression Increases the Chances of Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest: A Prospective Observational Cohort Study

OBJECTIVES

Following current cardiopulmonary resuscitation (CPR) guidelines, which recommend chest compressions at "the center of the chest," ~50% of patients experiencing out-of-hospital cardiac arrest (OHCA) undergo aortic valve (AV) compression, obstructing blood flow. We used resuscitative transesophageal echocardiography (TEE) to elucidate the impact of uncompressed vs. compressed AV on outcomes of adult patients experiencing OHCA.

DESIGN

Prospective observational cohort study.

SETTING

Single center.

PATIENTS

This study included adult OHCA patients undergoing resuscitative TEE in the emergency department. Patients were categorized into AV uncompressed or AV compressed groups based on TEE findings.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was sustained return of spontaneous circulation (ROSC). The secondary outcomes included end-tidal co2 (Et co2 ) during CPR, any ROSC, survival to ICU and hospital discharge, post-resuscitation withdrawal, and favorable neurologic outcomes at discharge. Additional analyses on intra-arrest arterial blood pressure (ABP) were also conducted. The sample size was pre-estimated at 37 patients/group. From October 2020 to January 2023, 76 patients were enrolled, 39 and 37 in the AV uncompressed and AV compressed groups, respectively. Intergroup baseline characteristics were similar. Compared with the AV compressed group, the AV uncompressed group had a higher probability of sustained ROSC (53.8% vs. 24.3%; adjusted odds ratio [aOR], 4.72; p = 0.010), any ROSC (56.4% vs. 32.4%; aOR, 3.30; p = 0.033), and survival to ICU (33.3% vs. 8.1%; aOR, 6.74; p = 0.010), and recorded higher initial diastolic ABP (33.4 vs. 11.5 mm Hg; p = 0.002) and a larger proportion achieving diastolic ABP greater than 20 mm Hg during CPR (93.8% vs. 33.3%; p < 0.001). The Et co2 , post-resuscitation withdrawal, and survival to discharge revealed no significant intergroup differences. No patients were discharged with favorable neurologic outcomes. Uncompressed AV seemed critical for sustained ROSC across all subgroups.

CONCLUSIONS

Absence of AV compression during OHCA resuscitation is associated with an increased chance of ROSC and survival to ICU. However, its effect on long-term outcomes remains unclear.

2024 RECOVER Guidelines: Monitoring. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review evidence on and devise treatment recommendations for patient monitoring before, during, and following CPR in dogs and cats, and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to peri-CPR monitoring following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by Monitoring Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Thirteen questions pertaining to hemodynamic, respiratory, and metabolic monitoring practices for identification of cardiopulmonary arrest, quality of CPR, and postcardiac arrest care were examined, and 24 treatment recommendations were formulated. Of these, 5 recommendations pertained to aspects of end-tidal CO2 (ETco2) measurement. The recommendations were founded predominantly on very low quality of evidence, with some based on expert opinion.

CONCLUSIONS

The Monitoring Domain authors continue to support initiation of chest compressions without pulse palpation. We recommend multimodal monitoring of patients at risk of cardiopulmonary arrest, at risk of re-arrest, or under general anesthesia. This report highlights the utility of ETco2 monitoring to verify correct intubation, identify return of spontaneous circulation, evaluate quality of CPR, and guide basic life support measures. Treatment recommendations further suggest intra-arrest evaluation of electrolytes (ie, potassium and calcium), as these may inform outcome-relevant interventions.

Differences in Pathophysiology and Treatment Efficacy Based on Heterogeneous Out-of-Hospital Cardiac Arrest

Out-of-hospital cardiac arrest (OHCA) is heterogeneous in terms of etiology and severity. Owing to this heterogeneity, differences in outcome and treatment efficacy have been reported from case to case; however, few reviews have focused on the heterogeneity of OHCA. We conducted a literature review to identify differences in the prognosis and treatment efficacy in terms of CA-related waveforms (shockable or non-shockable), age (adult or pediatric), and post-CA syndrome severity and to determine the preferred treatment for patients with OHCA to improve outcomes.

The Association of Prehospital End-Tidal Carbon Dioxide with Survival Following Out-of-Hospital Cardiac Arrest

OBJECTIVE

End tidal carbon dioxide (ETCO2) is often used to assess ventilation and perfusion during cardiac arrest resuscitation. However, few data exist evaluating the relationship between ETCO2 values and mortality in the context of contemporary resuscitation practices. We aimed to explore the association between ETCO2 and mortality following out-of-hospital cardiac arrest (OHCA).

METHODS

We used the 2018-2021 ESO annual datasets to query all non-traumatic OHCA patients with attempted resuscitation. Patients with documented DNR/POLST, EMS-witnessed arrest, ROSC after bystander CPR only, or < 2 documented ETCO2 values were excluded. The lowest and highest ETCO2 values recorded during the total prehospital interval, in addition to the pre- and post-ROSC intervals for resuscitated patients, were calculated. Multivariable logistic regression models adjusted for age, sex, initial rhythm, witnessed status, bystander CPR, etiology, OHCA location, sodium bicarbonate administration, number of milligrams of epinephrine administered, and response interval were used to evaluate the association between measures of ETCO2 and mortality.

RESULTS

Hospital outcome data were available for 14,122 patients, and 2,209 (15.6%) were classified as surviving to discharge. Compared to patients with maximum prehospital ETCO2 values of 30-40 mmHg, odds of mortality were increased for patients with maximum prehospital ETCO2 values of <20 mmHg (aOR: 3.5 [2.1, 5,9]), 20-29 mmHg (aOR: 1.5 [1.1, 2.1]), and >50 mmHg (aOR: 1.5 [1.2, 1.8]). After 20 minutes of ETCO2 monitoring, <12% of patients had ETCO2 values <10 mmHg. This cutpoint was 96.7% specific and 6.9% sensitive for mortality.

CONCLUSION

In this dataset, both high and low ETCO2 values were associated with increased mortality. Contemporary resuscitation practices may make low ETCO2 values uncommon, and field termination decision algorithms should not use ETCO2 values in isolation.

Volumetric capnography and return of spontaneous circulation in an experimental model of pediatric asphyxial cardiac arrest

A secondary analysis of a randomized study was performed to study the relationship between volumetric capnography (VCAP) and arterial CO2 partial pressure (PCO2) during cardiopulmonary resuscitation (CPR) and to analyze the ability of these parameters to predict the return of spontaneous circulation (ROSC) in a pediatric animal model of asphyxial cardiac arrest (CA). Asphyxial CA was induced by sedation, muscle relaxation and extubation. CPR was started 2 min after CA occurred. Airway management was performed with early endotracheal intubation or bag-mask ventilation, according to randomization group. CPR was continued until ROSC or 24 min of resuscitation. End-tidal carbon dioxide (EtCO2), CO2 production (VCO2), and EtCO2/VCO2/kg ratio were continuously recorded. Seventy-nine piglets were included, 26 (32.9%) of whom achieved ROSC. EtCO2 was the best predictor of ROSC (AUC 0.72, p < 0.01 and optimal cutoff point of 21.6 mmHg). No statistical differences were obtained regarding VCO2, VCO2/kg and EtCO2/VCO2/kg ratios. VCO2 and VCO2/kg showed an inverse correlation with PCO2, with a higher correlation coefficient as resuscitation progressed. EtCO2 also had an inverse correlation with PCO2 from minute 18 to 24 of resuscitation. Our findings suggest that EtCO2 is the best VCAP-derived parameter for predicting ROSC. EtCO2 and VCO2 showed an inverse correlation with PCO2. Therefore, these parameters are not adequate to measure ventilation during CPR.

End-tidal carbon dioxide (ETCO2) at intubation and its increase after 10 minutes resuscitation predicts survival with good neurological outcome in out-of-hospital cardiac arrest patients

AIM

To evaluate whether end-tidal carbon dioxide (ETCO2) value at intubation and its early increase (10 min) after intubation predict both the survival to hospital admission and the survival at hospital discharge, including good neurological outcome (CPC 1-2), in patients with out-of-hospital cardiac arrest (OHCA).

METHODS

All consecutive OHCA patients of any etiology between 2015 and 2018 in Pavia Province (Italy) and Ticino Region (Switzerland) were considered. Patients died before ambulance arrival, with a "do-not-resuscitate" order, without ETCO2 value or with incomplete data were excluded.

RESULTS

The study population consisted of 668 patients. An ETCO2 value at intubation > 20 mmHg and its increase 10 min after intubation were independent predictors (after correction for known predictors of OHCA outcome) of survival to hospital admission and survival at hospital discharge. Relative to hospital discharge with good neurological outcome, ETCO2 at intubation and its 10-min change were confirmed predictors both individually and in a bivariable analysis (OR 1.83, 95 %CI 1.02-3.3; p = 0.04 and OR 3.9, 95 %CI 1.97-7.74; p < 0.001, respectively). This was confirmed also when accounting for gender, age, etiology and location. After further adjustment for bystander and CPR status, presenting rhythm and EMS arrival time, the ETCO2 change remained an independent predictor.

CONCLUSIONS

ETCO2 value > 20 mmHg at intubation and its increase during resuscitation improve the prediction of survival at hospital discharge with good neurological outcome of OHCA patients. ETCO2 increase during resuscitation is a more powerful predictor than ETCO2 at intubation. A larger prospective study to confirm this finding appears warranted.

Association between Trajectories of End-tidal Carbon Dioxide and Return of Spontaneous Circulation among Emergency Department Patients with Out-of-hospital Cardiac Arrest

BACKGROUND

We aimed to identify distinct trajectories of end-tidal carbon dioxide (EtCO₂) during cardiopulmonary resuscitation in patients with out-of-hospital cardiac arrest (OHCA) and to investigate the association between EtCO₂ trajectories and OHCA outcomes.

METHODS

This was a secondary analysis of a prospectively collected database on adult patients with OHCA who had been resuscitated in the emergency department of a tertiary medical center between 2015 and 2020. The primary outcome was the return of spontaneous circulation (ROSC). Group-based trajectory modelling was used to identify the EtCO₂ trajectories. Multivariable logistic regression analysis was performed to evaluate the association between EtCO₂ trajectories and ROSC. The predictive performance of the EtCO₂ trajectories was assessed using the area under the receiver operating characteristic curve (AUC).

RESULTS

The study comprised 655 patients with OHCA. In the primary analysis, three distinct EtCO₂ trajectories, including 10-mmHg, 30-mmHg, and 50-mmHg trajectories, were identified. Compared with the 10-mmHg trajectory, both 30-mmHg (odds ratio [OR]: 4.66, 95% confidence interval [CI]: 3.15-6.90) and 50-mmHg (OR: 7.58, 95% CI: 4.30-13.35) trajectories were associated with a higher likelihood of ROSC. In a sensitivity analysis of excluding EtCO₂ measured before tracheal intubation or after sodium bicarbonate administration, the predictive ability of the identified EtCO₂ trajectories remained. As a single predictor of ROSC, EtCO₂ trajectories had an acceptable discriminative performance (AUC: 0.69, 95% CI: 0.66-0.73).

CONCLUSION

Three distinct EtCO₂ trajectories during cardiopulmonary resuscitation were identified and significantly associated with outcomes. Early identification of these EtCO₂ trajectories could potentially guide the ongoing resuscitation efforts.

Early mechanical cardiopulmonary resuscitation can improve outcomes in patients with non-traumatic cardiac arrest in the emergency department

Objective

To compare the outcomes of patients with non-traumatic cardiac arrest (CA) who received early versus late mechanical cardiopulmonary resuscitation (CPR) with the Lund University Cardiac Assist System (LUCAS) device in the emergency department (ED).

Methods

This was a retrospective observational study in the ED of a single medical center performed from May 2018 to December 2019; 68 patients with CA were eligible. We grouped the patients according to the time to initiating LUCAS use after CA into an early group (≤4 minutes) and late group (>4 minutes).

Results

The rate of return of spontaneous circulation (ROSC) was higher in the early group vs the late group (69.2% vs 52.4%, respectively). The 4-hour survival rate was significantly higher in the early group vs the late group (83.3% vs 45.5%, respectively), and CPR duration was significantly shorter in the early group (23.3 ± 12.5 vs 31.1 ± 14.8 minutes, respectively).

Conclusion

Early mechanical CPR can improve the success of achieving ROSC and the 4-hour survival rate in patients with non-traumatic CA in the ED, considering that more benefits were observed in patients who received early vs late LUCAS device therapy.

New volumetric capnography-derived parameter: a potentially valuable tool for detecting hyperventilation during cardiopulmonary resuscitation in a porcine model

Background

Volumetric capnography is increasingly being applied in cardiopulmonary resuscitation. However, during cardiopulmonary resuscitation, the abnormal ventilation state affects the monitoring effect of the most commonly used capnography-derived parameter, the partial carbon dioxide end-tidal pressure (PetCO₂). In this study, we evaluated the ability of a new volumetric capnography-derived parameter, the ratio between the PetCO₂ and the volume of carbon dioxide (CO₂) eliminated per min and per kilogram of body weight, for detecting hyperventilation during cardiopulmonary resuscitation.

Methods

We used 12 porcine models of primary ventricular fibrillation-induced cardiac arrest. Ventricular fibrillation was induced and left untreated for 4 min. Standardized chest compressions were performed throughout the experiment using mechanical cardiopulmonary resuscitation. Following 5 min of normal ventilation as a washout period, each animal underwent 4 types of ventilation. The main outcome measures were the PetCO₂, the ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight with each ventilation type.

Results

Different ventilation types had a significant effect on the volumetric capnography-derived parameters. The PetCO₂ and ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight values during cardiopulmonary resuscitation was significantly higher in non-hyperventilating than in hyperventilating animals. The ratio reflected hyperventilation accurately and immediately, with an area under the curve (AUC) of 0.98. The optimal cut-off point of the ratio for discriminating hyperventilation from non-hyperventilation was 6.36, with a sensitivity and specificity of 0.99 and 0.89, respectively.

Conclusions

The ratio between the PetCO₂ and the volume of CO₂ eliminated per min and per kilogram of body weight showed good performance in discriminating hyperventilation from non-hyperventilation and was sensitive to changes in ventilation status. This ratio may be a valuable clinical indicator for monitoring the ventilation status during cardiopulmonary resuscitation.

Clinical outcomes and safety of passive leg raising in out-of-hospital cardiac arrest: a randomized controlled trial

BACKGROUND

There are data suggesting that passive leg raising (PLR) improves hemodynamics during cardiopulmonary resuscitation (CPR). This trial aimed to determine the effectiveness and safety of PLR during CPR in out-of-hospital cardiac arrest (OHCA).

METHODS

We conducted a randomized controlled trial with blinded assessment of the outcomes that assigned adults OHCA to be treated with PLR or in the flat position. The trial was conducted in the Camp de Tarragona region. The main end point was survival to hospital discharge with good neurological outcome defined as cerebral performance category (CPC 1-2). To study possible adverse effects, we assessed the presence of pulmonary complications on the first chest X-rays, brain edema on the computerized tomography (CT) in survivors and brain and lungs weights from autopsies in non-survivors.

RESULTS

In total, 588 randomized cases were included, 301 were treated with PLR and 287 were controls. Overall, 67.8% were men and the median age was 72 (IQR 60-82) years. At hospital discharge, 3.3% in the PLR group and 3.5% in the control group were alive with CPC 1-2 (OR 0.9; 95% CI 0.4-2.3, p = 0.91). No significant differences in survival at hospital admission were found in all patients (OR 1.0; 95% CI 0.7-1.6, p = 0.95) and among patients with an initial shockable rhythm (OR 1.7; 95% CI 0.8-3.4, p = 0.15). There were no differences in pulmonary complication rates in chest X-rays [7 (25.9%) vs 5 (17.9%), p = 0.47] and brain edema on CT [5 (29.4%) vs 10 (32.6%), p = 0.84]. There were no differences in lung weight [1223 mg (IQR 909-1500) vs 1239 mg (IQR 900-1507), p = 0.82] or brain weight [1352 mg (IQR 1227-1457) vs 1380 mg (IQR 1255-1470), p = 0.43] among the 106 autopsies performed.

CONCLUSION

In this trial, PLR during CPR did not improve survival to hospital discharge with CPC 1-2. No evidence of adverse effects has been found. Clinical trial registration ClinicalTrials.gov: NCT01952197, registration date: September 27, 2013, https://clinicaltrials.gov/ct2/show/NCT01952197 .

Pediatric In-Hospital Cardiac Arrest and Cardiopulmonary Resuscitation in the United States: A Review

IMPORTANCE

Pediatric in-hospital cardiac arrest (IHCA) occurs frequently and is associated with high morbidity and mortality. The objective of this narrative review is to summarize the current knowledge and recommendations regarding pediatric IHCA and cardiopulmonary resuscitation (CPR).

OBSERVATIONS

Each year, more than 15 000 children receive CPR for cardiac arrest during hospitalization in the United States. As many as 80% to 90% survive the event, but most patients do not survive to hospital discharge. Most IHCAs occur in intensive care units and other monitored settings and are associated with respiratory failure or shock. Bradycardia with poor perfusion is the initial rhythm in half of CPR events, and only about 10% of events have an initial shockable rhythm. Pre-cardiac arrest systems focus on identifying at-risk patients and ensuring that they are in monitored settings. Important components of CPR include high-quality chest compressions, timely defibrillation when indicated, appropriate ventilation and airway management, administration of epinephrine to increase coronary perfusion pressure, and treatment of the underlying cause of cardiac arrest. Extracorporeal CPR and measurement of physiological parameters are evolving areas in improving outcomes. Structured post-cardiac arrest care focused on targeted temperature management, optimization of hemodynamics, and careful intensive care unit management is associated with improved survival and neurological outcomes.

CONCLUSIONS AND RELEVANCE

Pediatric IHCA occurs frequently and has a high mortality rate. Early identification of risk, prevention, delivery of high-quality CPR, and post-cardiac arrest care can maximize the chances of achieving favorable outcomes. More research in this field is warranted.

Maximum Value of End-Tidal Carbon Dioxide Concentrations during Resuscitation as an Indicator of Return of Spontaneous Circulation in out-of-Hospital Cardiac Arrest

Background: The end-tidal carbon dioxide (ETCO₂) concentration during resuscitation (CPR) of an out-of-hospital cardiac arrest (OHCA) has an increasingly well-known prognostic value. Nevertheless, few studies have investigated its maximum value in different etiologies. Methods: It was a retrospective, observational, multicentre study from the French OHCA Registry. All adult OHCA with a known maximum value of ETCO₂ during CPR were included. The primary end-point was to determine the area under the receiver operating characteristic curve (AUROC) of the maximum value of ETCO₂ during resuscitation for the return of spontaneous circulation (ROSC). Results: Of the 53,048 eligible subjects from 2011 to 2018, ETCO₂ was known in 32,249 subjects (61%). Among them, there were 9.2% of traumatic OHCA, 37.7% of suspected cardiac etiology and 16.4% of suspected respiratory etiology. The AUROC of maximum value of ETCO₂ during CPR to achieve ROSC was 0.887 95CI [0.875-0.898] in traumatic OHCA, 0.772 95CI [0.765-0.780] in suspected cardiac etiology and 0.802 95CI [0.791-0.812] in suspected respiratory etiology. The threshold with no survivors at d-30 was <10 mmHg for traumatic etiologies and <6 mmHg for suspected cardiac and respiratory causes. The probability of ROSC increased with the value of ETCO₂ in the 3 etiologies studied. Conclusions: The maximum value of ETCO₂ during OHCA resuscitation was strongly associated with ROSC, especially in the case of a traumatic cause. This suggests that a single elevated ETCO₂ value, regardless of time, could help to predict the outcome.

Phenotyping Cardiac Arrest: Bench and Bedside Characterization of Brain and Heart Injury Based on Etiology

OBJECTIVES

Cardiac arrest etiology may be an important source of between-patient heterogeneity, but the impact of etiology on organ injury is unknown. We tested the hypothesis that asphyxial cardiac arrest results in greater neurologic injury than cardiac etiology cardiac arrest (ventricular fibrillation cardiac arrest), whereas ventricular fibrillation cardiac arrest results in greater cardiovascular dysfunction after return of spontaneous circulation.

DESIGN

Prospective observational human and randomized animal study.

SETTING

University laboratory and ICUs.

PATIENTS

Five-hundred forty-three cardiac arrest patients admitted to ICU.

SUBJECTS

Seventy-five male Sprague-Dawley rats.

INTERVENTIONS

We examined neurologic and cardiovascular injury in Isoflurane-anesthetized rat cardiac arrest models matched by ischemic time. Hemodynamic and neurologic outcomes were assessed after 5 minutes no flow asphyxial cardiac arrest or ventricular fibrillation cardiac arrest. Comparison was made to injury patterns observed after human asphyxial cardiac arrest or ventricular fibrillation cardiac arrest.

MEASUREMENTS AND MAIN RESULTS

In rats, cardiac output (20 ± 10 vs 45 ± 9 mL/min) and pH were lower and lactate higher (9.5 ± 1.0 vs 6.4 ± 1.3 mmol/L) after return of spontaneous circulation from ventricular fibrillation cardiac arrest versus asphyxial cardiac arrest (all p < 0.01). Asphyxial cardiac arrest resulted in greater early neurologic deficits, 7-day neuronal loss, and reduced freezing time (memory) after conditioned fear (all p < 0.05). Brain antioxidant reserves were more depleted following asphyxial cardiac arrest. In adjusted analyses, human ventricular fibrillation cardiac arrest was associated with greater cardiovascular injury based on peak troponin (7.8 ng/mL [0.8-57 ng/mL] vs 0.3 ng/mL [0.0-1.5 ng/mL]) and ejection fraction by echocardiography (20% vs 55%; all p < 0.0001), whereas asphyxial cardiac arrest was associated with worse early neurologic injury and poor functional outcome at hospital discharge (n = 46 [18%] vs 102 [44%]; p < 0.0001). Most ventricular fibrillation cardiac arrest deaths (54%) were the result of cardiovascular instability, whereas most asphyxial cardiac arrest deaths (75%) resulted from neurologic injury (p < 0.0001).

CONCLUSIONS

In transcending rat and human studies, we find a consistent phenotype of heart and brain injury after cardiac arrest based on etiology: ventricular fibrillation cardiac arrest produces worse cardiovascular dysfunction, whereas asphyxial cardiac arrest produces worsened neurologic injury associated with greater oxidative stress.

Initial end-tidal carbon dioxide as a predictive factor for return of spontaneous circulation in nonshockable out-of-hospital cardiac arrest patients: A retrospective observational study

BACKGROUND

Early outcome prediction in out-of-hospital cardiac arrest is still a challenge. End-tidal carbon dioxide (ETCO2) has been shown to be a reliable parameter to reflect the quality of cardiopulmonary resuscitation and the chance of return of spontaneous circulation (ROSC).

OBJECTIVES

This study assessed the validity of early capnography as a predictive factor for ROSC and survival in out-of-hospital cardiac arrest victims with an underlying nonshockable rhythm.

DESIGN

Retrospective observational study.

SETTING/PATIENTS

During a 2-year observational period, data from 2223 out-of-hospital cardiac arrest victims within the city of Vienna were analysed. The focus was on the following patients: age more than 18 years, an underlying nonshockable rhythm, and advanced airway management within the first 15 min of advanced life support with subsequent capnography.

INTERVENTION

No specific intervention was set in this observational study.

MAIN OUTCOME MEASURES

The first measured ETCO2, assessed immediately after placement of an advanced airway, was used for further analysis. The primary outcome was defined as sustained ROSC, and the secondary outcome was 30-day survival.

RESULTS

A total of 526 patients met the inclusion criteria. These were stratified into three groups according to initial ETCO2 values (<20, 20 to 45, >45 mmHg). Baseline data and resuscitation factors were similar among all groups. The odds of sustained ROSC and survival were significantly higher for patients presenting with higher values of initial ETCO2 (>45 mmHg): 3.59 [95% CI, 2.19 to 5.85] P = 0.001 and 5.02 [95% CI, 2.25 to 11.23] P = 0.001, respectively. On the contrary ETCO2 levels less than 20 mmHg were associated with significantly poorer outcomes.

CONCLUSION

Patients with a nonshockable out-of-hospital cardiac arrest who presented with higher values of initial ETCO2 had an increased chance of sustained ROSC and survival. This finding could help decision making as regards continuation of resuscitation efforts.

Quantitative end-tidal CO2 can predict increase in heart rate during infant cardiopulmonary resuscitation

Aim

To determine the end-tidal CO₂ (ETCO₂) value that predicts a HR > 60 beats per minute (bpm) with the best sensitivity and specificity during neonatal/infant cardiopulmonary resuscitation (CPR) defined as chest compressions ± epinephrine in neonates/infants admitted to a CVICU/PICU.

Methods

This was a retrospective cohort study from 1/1/08 to 12/31/12 of all infants ≤6 month of age who received CPR and had ETCO₂ documented during serial resuscitations in the pediatric (PICU) or pediatric cardiovascular intensive care units (CVICU) of Children's Medical Center of Dallas. A receiver operator characteristic (ROC) curve was generated to determine the ETCO₂ cut-off with the best sensitivity and specificity for predicting HR > 60 bpm. Each ETCO₂ value was correlated to the infant's HR at that specific time.

Results

CPR was provided for 165 infants of which 49 infants had quantitative ETCO₂ documented so only these infants were included. The majority were in the CVICU (81%) and intubated (84%). Mean gestational age was 36 ± 3 weeks and median age (interquartile range) at time of CPR was 30 (16-96) days. An ETCO₂ between 17 and 18 mmHg correlated with the highest sensitivity and specificity for return of a HR > 60 bpm. Area under the curve for the ROC is 0.835.

Conclusions

This study provides critical clinical information regarding correlation between ETCO₂ values and an adequate rise in heart rate in neonates and young infants during CPR. Quantitative ETCO₂ monitoring allows CPR to progress uninterrupted without need to pause to check heart rate every 60 seconds until the critical ETCO₂ threshold is reached. Quantitative ETCO₂ monitoring as an adjunct to cardiac monitoring during infant CPR might enhance perfusion and improve outcomes.

Physiology-directed cardiopulmonary resuscitation: advances in precision monitoring during cardiac arrest

PURPOSE OF REVIEW

We review the recent advances in physiologic monitoring during cardiac arrest and offer an evidence-based framework for prioritizing physiologic targets during cardiopulmonary resuscitation (CPR).

RECENT FINDINGS

Current CPR guidelines recommend a uniform approach for all patients in cardiac arrest, but newer data support a precision strategy that uses the individual patient's physiology to guide resuscitation. Coronary perfusion pressure and arterial DBP are associated with survival outcomes in recent animal and human studies. End-tidal carbon dioxide is a reasonable noninvasive alternative, but may be inferior to invasive hemodynamic endpoints. Cerebral oximetry and cardiac ultrasound are emerging physiologic indicators of CPR effectiveness.

SUMMARY

Physiologic monitoring can and should be used to deliver precision CPR whenever possible and may improve outcomes after cardiac arrest.

Relationship between hemodynamic parameters and severity of ischemia-induced left ventricular wall thickening during cardiopulmonary resuscitation of consistent quality

Ischemia-induced left ventricular (LV) wall thickening compromises the hemodynamic effectiveness of cardiopulmonary resuscitation (CPR). However, accurate assessment of the severity of ischemia-induced LV wall thickening during CPR is challenging. We investigated, in a swine model, whether hemodynamic parameters, including end-tidal carbon dioxide (ETCO₂) level, are linearly associated with the severity of ischemia-induced LV wall thickening during CPR of consistent quality. We retrospectively analyzed 96 datasets for ETCO₂ level, arterial pressure, LV wall thickness, and the percent of measured end-diastolic volume (%EDV) relative to EDV at the onset of ventricular fibrillation from eight pigs. Animals underwent advanced cardiovascular life support based on resuscitation guidelines. During CPR, LV wall thickness progressively increased while %EDV progressively decreased. Systolic and diastolic arterial pressure and ETCO₂ level were significantly correlated with LV wall thickness and %EDV. Linear mixed effect models revealed that, after adjustment for significant covariates, systolic and diastolic arterial pressure were not associated with LV wall thickness or %EDV. ETCO₂ level had a significant linear relationship with %EDV (P = 0.004). However, it could explain only 28.2% of the total variance of %EDV in our model. In conclusion, none of the hemodynamic parameters examined in this study appeared to provide sufficient information on the severity of ischemia-induced LV wall thickening.

A Dynamic Model of Rescuer Parameters for Optimizing Blood Gas Delivery during Cardiopulmonary Resuscitation

Introduction

The quality of cardiopulmonary resuscitation (CPR) has been shown to impact patient outcomes. However, post-CPR morbidity and mortality remain high, and CPR optimization is an area of active research. One approach to optimizing CPR involves establishing reliable CPR performance measures and then modifying CPR parameters, such as compressions and ventilator breaths, to enhance these measures. We aimed to define a reliable CPR performance measure, optimize the CPR performance based on the defined measure and design a dynamically optimized scheme that varies CPR parameters to optimize CPR performance.

Materials and Methods

We selected total blood gas delivery (systemic oxygen delivery and carbon dioxide delivery to the lungs) as an objective function for maximization. CPR parameters were divided into three categories: rescuer dependent, patient dependent, and constant parameters. Two optimization schemes were developed using simulated annealing method: a global optimization scheme and a sequential optimization scheme.

Results and Discussion

Variations of CPR parameters over CPR sequences (cycles) were analyzed. Across all patient groups, the sequential optimization scheme resulted in significant enhancement in the effectiveness of the CPR procedure when compared to the global optimization scheme.

Conclusions

Our study illustrates the potential benefit of considering dynamic changes in rescuer-dependent parameters during CPR in order to improve performance. The advantage of the sequential optimization technique stemmed from its dynamically adapting effect. Our CPR optimization findings suggest that as CPR progresses, the compression to ventilation ratio should decrease, and the sequential optimization technique can potentially improve CPR performance. Validation in vivo is needed before implementing these changes in actual practice.

Data supporting the use of end-tidal carbon dioxide (ETCO2) measurement to guide management of cardiac arrest: A systematic review

The data presented in this article are related to the research article, "The Use of End-Tidal Carbon Dioxide (ETCO2) Measurement to Guide Management of Cardiac Arrest: A Systematic Review" [1]. This article is a systematic review and meta-analysis of existing data on the subject of whether any level of end-tidal carbon dioxide (ETCO2) measured during cardiopulmonary resuscitation (CPR) correlates with return of spontaneous circulation (ROSC) or survival in adult patients experiencing cardiac arrest in any setting. These data are made publicly available to enable critical or extended analyses.

De l’entrée à la sortie du service de réanimation adulte : une mise au point sur l’utilisation courante du monitoring du CO2 expiré

L’objectif de cette mise au point est d’effectuer une revue des indications de l’utilisation du monitorage du CO2 expiré en réanimation adulte. De par sa physiologie, sa mesure est un reflet de l’état hémodynamique, respiratoire et métabolique du patient. La spectrométrie infrarouge est la méthode de mesure la plus courante. La capnographie commune (CO2 expiré en fonction du temps) est divisée en plusieurs phases dont l’analyse visuelle peut faire évoquer de nombreuses anomalies ventilatoires. La capnographie volumétrique fournit une mesure de l’espace mort. La capnométrie est recommandée en réanimation pour contrôler l’intubation trachéale ou bien au cours d’un arrêt cardiorespiratoire comme facteur pronostique. Tout patient traité par ventilation mécanique invasive, surtout lors d’un transport, doit être équipé d’un capnomètre afin d’anticiper toute complication respiratoire (extubation, bronchospasme, hypoventilation). La pression de fin d’expiration en CO2 (PetCO2) est une évaluation de la pression artérielle en CO2 (PaCO2) utile pour limiter le nombre de prélèvements biologiques, par exemple en neuroréanimation, mais de nombreux facteurs font varier le gradient entre ces deux valeurs. Les études n’apportent pas de preuve pour l’utilisation de la capnographie volumétrique dans le diagnostic d’embolie pulmonaire en réanimation. Chez les patients souffrant de syndrome de détresse respiratoire aiguë, la littérature médicale n’apporte pas de preuve suffisante pour un intérêt en pratique clinique courante de la capnométrie volumétrique qui semble limitée dans ce cas à la recherche.

Predicting ROSC in out-of-hospital cardiac arrest using expiratory carbon dioxide concentration: Is trend-detection instead of absolute threshold values the key?

AIM

Guidelines recommend detecting return of spontaneous circulation (ROSC) by a rising concentration of carbon dioxide in the exhalation air. As CO₂ is influenced by numerous factors, no absolute cut-off values of CO₂ to detect ROSC are agreed on so far. As trends in CO₂ might be less affected by influencing factors, we investigated an approach which is based on detecting CO₂-trends in real-time.

METHODS

We conducted a retrospective case-control study on 169 CO₂ time series from out of hospital cardiac arrests resuscitated by Muenster City Ambulance-Service, Germany. A recently developed statistical method for real-time trend-detection (SCARM) was applied to each time series. For each series, the percentage of time points with detected positive and negative trends was determined.

RESULTS

ROSC time series had larger percentages of positive trends than No-ROSC time series (p=0.003). The median percentage of positive trends was 15% in the ROSC time series (IQR: 5% to 23%) and 7% in the No-ROSC time series (IQR: 3% to 14%). A receiver operating characteristic (ROC) analysis yielded an optimal threshold of 13% to differentiate between ROSC and No-ROSC cases with a specificity of 58.4% and sensitivity of 73.9%; the area under the curve was 63.5%.

CONCLUSION

Patients with ROSC differed from patients without ROSC as to the percentage of detected CO₂ trends, indicating the potential of our real-time trend-detection approach. Since the study was designed as a proof of principle and its calculated specificity and sensitivity are low, more research is required to implement CO₂-trend-detection into clinical use.

Capnography Use During Intubation and Cardiopulmonary Resuscitation in the Pediatric Emergency Department

OBJECTIVE

Capnography is indicated as a guide to assess and monitor both endotracheal intubation and cardiopulmonary resuscitation (CPR). Our primary objective was to determine the effect of the 2010 American Heart Association (AHA) guidelines on the frequency of capnography use during critical events in children in the emergency department (ED). Our secondary objective was to examine associations between patient characteristics and capnography use among these patients.

METHODS

A retrospective chart review was performed on children aged 0 to 21 years who were intubated or received CPR in 2 academic children's hospital EDs between January 2009 and December 2012. Age, sex, time of arrival, medical or traumatic cause, length of CPR, return of spontaneous circulation (ROSC), documented use of capnography and colorimetry, capnography values, and adverse events were recorded.

RESULTS

Two hundred ninety-two patients were identified and analyzed. Intubation occurred in 95% of cases and CPR in 30% of cases. Capnography was documented in only 38% of intubated patients and 13% of patients requiring CPR. There was an overall decrease in capnography use after publication of the 2010 AHA recommendations (P = 0.05). Capnography use was associated with a longer duration of CPR and return of spontaneous circulation.

CONCLUSIONS

Despite the 2010 AHA recommendations, a minority of critically ill children are being monitored with capnography and an unexpected decrease in documented use occurred among our sample. Further education and implementation of capnography should take place to improve the use of this monitoring device for critically ill pediatric patients in the ED.

Initial end-tidal CO2 partial pressure predicts outcomes of in-hospital cardiac arrest

INTRODUCTION

Monitoring the partial pressure of end-tidal carbon dioxide (PEtco₂) has been advocated since 2010 as an index of resuscitation efforts. However, related research has largely focused on out-of-hospital cardiac arrest victims. In-hospital cardiac arrest (IHCA) differs in terms of etiologies and demographics, the merit of initial PEtco₂ values was explored.

METHODS

This was a retrospective study in a single medical center between February 2011 and August 2014. Eligible subjects had suffered nontraumatic IHCA in the emergency department, where resuscitation was performed in accord with 2010 American Heart Association guidelines. Patients with initial PEtco₂ recordings via capnography were recruited.

RESULTS

A total of 353 IHCA events with initial PEtco₂ were recorded in 202 patients (male, 61.4%; mean age, 67.0 ± 16.2 years). Shockable rhythm (ventricular tachycardia/ventricular fibrillation) accounted for 11.8%. A cut point of 25.5 mm Hg was established for initial PEtco₂, creating 2 tiers of sustained return of spontaneous circulation (ROSC) that differed significantly in cumulative survival probability (log rank test, P = .002). For patients with initial PEtco₂ <25.5 mm Hg, survival benefit ceased at an earlier point in resuscitation, whereas above this threshold, the probability of survival cumulatively increased for a longer period. In multivariate analysis, initial PEtco₂ >25.5 mm Hg was found independently predictive of sustained ROSC (odds ratio, 2.64; 95% confidence interval, 1.43-4.88; P = .002), and survival to discharge (odds ratio, 3.10; 95% confidence interval, 1.26-7.60; P = .014), but failed to correlate with neurologic outcome.

CONCLUSION

In IHCA, the therapeutic threshold for initial PEtco₂ should set fairly higher to encourage more pulmonary flow and increase the likelihood of sustained ROSC.

Arterial pressure, end-tidal carbon dioxide, and central venous oxygen saturation in reflecting compression depth

BACKGROUND

We sought to investigate the utility of arterial pressure, end-tidal carbon dioxide (ETCO2 ), and central venous oxygen saturation (SCVO2 ) to guide compression depth adjustment. Thus, in a pig model of cardiac arrest, we observed these parameters during cardiopulmonary resuscitation (CPR) with optimal and suboptimal compression depths.

METHODS

Sixteen pigs underwent three experimental sessions after induction of ventricular fibrillation. First, the animals received two 4-min CPR trials with either optimal (20% of the anteroposterior diameter) or suboptimal (70% of the optimal depth) compression depth. Second, the animals received two 5-min CPR trials with optimal compression depth, in which adrenaline (0.02 mg/kg) or saline placebo was administered. Third, the animals randomly received compression with either optimal or suboptimal depth during advanced cardiovascular life support.

RESULTS

The systolic arterial pressure reflected compression depth most accurately and immediately (area under the curve [AUC], 0.895-0.939 without adrenaline and 0.928-1.000 with adrenaline). Although the response of ETCO2 to the change in compression depth was 0.5 min slower than that of the systolic arterial pressure, the performance of ETCO2 was comparable with that of systolic arterial pressure. SCVO2 did not reflect compression depth. Adrenaline administration remarkably increased systolic arterial pressure, diastolic arterial pressure, and coronary perfusion pressure but did not affect the ETCO2 readings.

CONCLUSION

In a pig model of cardiac arrest, systolic arterial pressure reflected compression depth immediately and accurately. The performance of ETCO2 was comparable with that of systolic arterial pressure. SCVO2 did not reflect compression depth.

Influence of Chest Compressions on Circulation during the Peri-Cardiac Arrest Period in Porcine Models

Objective

Starting chest compressions immediately after a defibrillation shock might be harmful, if the victim already had a return of spontaneous circulation (ROSC) and yet was still being subjected to external compressions at the same time. The objective of this study was to study the influence of chest compressions on circulation during the peri-cardiac arrest period.

Design

Prospective, randomized controlled study.

Setting

Animal experimental center in Peking Union Medical Collage Hospital, Beijing, China.

Subjects

Healthy 3-month-old male domestic pigs.

Interventions

44 pigs (28±2 kg) were randomly assigned to three groups: Group I (non-arrested with compressions) (n = 12); Group II (arrested with compressions only) (n = 12); Group III (ROSC after compressions and defibrillation) (n = 20). In Groups I and II, compressions were performed to a depth of 5cm (Ia and IIa, n = 6) or a depth of 3cm (Ib and IIb, n = 6) respectively, while in Group III, the animals which had just achieved ROSC (n = 18) were compressed to a depth of 5cm (IIIa, n = 6), a depth of 3cm (IIIb, n = 6), or had no compressions (IIIc, n = 6). Hemodynamic parameters were collected and analyzed.

Measurements and Findings

Hemodynamics were statistically different between Groups Ia and Ib when different depths of compressions were performed (p < 0.05). In Group II, compressions were beneficial and hemodynamics correlated with the depth of compressions (p < 0.05). In Group III, compressions that continued after ROSC produced a reduction in arterial pressure (p < 0.05).

Conclusions

Chest compressions might be detrimental to hemodynamics in the early post-ROSC stage. The deeper the compressions were, the better the effect on hemodynamics during cardiac arrest, but the worse the effect on hemodynamics after ROSC.

Comparison of Cerebral Metabolism between Pig Ventricular Fibrillation and Asphyxial Cardiac Arrest Models

BACKGROUND

Morbidity and mortality after resuscitation largely depend on the recovery of brain function. Ventricular fibrillation cardiac arrest (VFCA) and asphyxial cardiac arrest (ACA) are the two most prevalent causes of sudden cardiac death. Up to now, most studies have focused on VFCA. However, results from the two models have been largely variable. So, it is necessary to characterize the features of postresuscitation cerebral metabolism of both models.

METHODS

Forty-four Wuzhishan miniature inbred pigs were randomly divided into three groups: 18 for VFCA group, ACA group, respectively, and other 8 for sham-operated group (SHAM). VFCA was induced by programmed electric stimulation, and ACA was induced by endotracheal tube clamping. After 8 min without treatment, standard cardiopulmonary resuscitation (CPR) was initiated. Following neurological deficit scores (NDS) were evaluated at 24 h after achievement of spontaneous circulation, cerebral metabolism showed as the maximum standardized uptake value (SUVmax) was measured by 18 F-fluorodeoxyglucose positron emission tomography/computed tomography. Levels of serum markers of brain injury, neuron specific enolase (NSE), and S100β were quantified with an enzyme-linked immunosorbent assay.

RESULTS

Compared with VFCA group, fewer ACA animals achieved restoration of spontaneous circulation (61.1% vs. 94.4%, P < 0.01) and survived 24-h after resuscitation (38.9% vs. 77.8%, P < 0.01) with worse neurological outcome (NDS: 244.3 ± 15.3 vs. 168.8 ± 9.71, P < 0.01). The CPR duration of ACA group was longer than that of VFCA group (8.1 ± 1.2 min vs. 4.5 ± 1.1 min, P < 0.01). Cerebral energy metabolism showed as SUVmax in ACA was lower than in VFCA (P < 0.05 or P < 0.01). Higher serum biomarkers of brain damage (NSE, S100β) were found in ACA than VFCA after resuscitation (P < 0.01).

CONCLUSIONS

Compared with VFCA, ACA causes more severe cerebral metabolism injuries with less successful resuscitation and worse neurological outcome.

The pathophysiologies of asphyxial vs dysrhythmic cardiac arrest: implications for resuscitation and post-event management

BACKGROUND

Cardiac arrest is not a uniform condition and significant heterogeneity exists within all victims with regard to the cause of cardiac arrest. Primary cardiac (dysrhythmic) and asphyxial causes together are responsible for most cases of cardiac arrest at all age groups. The purpose of this article is to review the pathophysiologic differences between dysrhythmic and asphyxial cardiac arrest in the prearrest period, during the no-flow state, and after successful cardiopulmonary resuscitation.

METHODS

The electronic databases of PubMed/Medline, Scopus, and Cochrane were searched for relevant literature and studies.

RESULTS/DISCUSSION

Significant differences exist between dysrhythmic and asphyxial cardiac arrest regarding their pathophysiologic pathways and affect consequently the postresuscitation period. Laboratory data indicate that asphyxial cardiac arrest leads to more widespread postresuscitation brain damage compared with dysrhythmic cardiac arrest. Regarding postresuscitation myocardial dysfunction, few studies have addressed a comparison of the 2 conditions with controversial results.

CONCLUSIONS

Asphyxial cardiac arrest differs significantly from dysrhythmic cardiac arrest with regard to pathophysiologic mechanisms, neuropathologic damage, postresuscitation organ dysfunction, and response to therapy. Both conditions should be considered and treated in a different manner.

A Review of Carbon Dioxide Monitoring During Adult Cardiopulmonary Resuscitation

Although high quality cardiopulmonary resuscitation is one of the most significant factors related to favourable outcome, its quality depends on many components, such as airway management, compression depth and chest recoil, hands-off time, and early defibrillation. The most common way of controlling the resuscitation efforts is monitoring of end-tidal carbon dioxide. The International Liaison Committee on Resuscitation suggests this method both for in-hospital and out-of-hospital cardiac arrest. However, despite the abundant human and animal studies supporting the usefulness of end-tidal carbon dioxide, its optimal values during cardiopulmonary resuscitation remain controversial. In this review, the advantages and effectiveness of end-tidal carbon dioxide during cardiopulmonary resuscitation are discussed and specific target values are suggested based on the available literature.

Initial end-tidal carbon dioxide as a prognostic indicator for inpatient PEA arrest

AIM

Investigate the relationship of initial PetCO2 values of patients during inpatient pulseless electrical activity (PEA) cardiopulmonary arrest with return of spontaneous circulation (ROSC) and survival to discharge.

METHODS

This study was performed in two urban, academic inpatient hospitals. Patients were enrolled from July 2009 to July 2013. A comprehensive database of all inpatient resuscitative events is maintained at these institutions, including demographic, clinical, and outcomes data. Arrests are stratified by primary etiology of arrest using a priori criteria. Inpatients with PEA arrest for whom recorded PetCO2 was available were included in the analysis. Capnography data obtained after ROSC and/or more than 10 min after initiation of CPR were excluded. Multivariable logistic regression was used to explore the association between initial PetCO2 >20 mmHg and both ROSC and survival-to-discharge.

RESULTS

A total of 50 patients with PEA arrest and pre-ROSC capnography were analyzed. CPR continued an average of 11.8 min after initial PetCO2 was recorded confirming absence of ROSC at time of measurement. Initial PetCO2 was higher in patients with versus without eventual ROSC (25.3 ± 14.4 mmHg versus 13.4 ± 6.9 mmHg, P = 0.003). After adjusting for age, gender, and arrest location (ICU versus non-ICU), initial PetCO2 >20 mmHg was associated with increased likelihood of ROSC (adjusted OR 4.8, 95% CI 1.2-19.2, P = 0.028). Initial PetCO2 was not significantly associated with survival-to-discharge (P = 0.251).

CONCLUSIONS

Initial PetCO2 >20 mmHg during CPR was associated with ROSC but not survival-to-discharge among inpatient PEA arrest victims. This analysis is limited by relatively small sample size.

Changes of end-tidal carbon dioxide during cardiopulmonary resuscitation from ventricular fibrillation versus asphyxial cardiac arrest

BACKGROUND

Partial pressure of end-tidal carbon dioxide (PETCO2) has been used to monitor the effectiveness of precordial compression (PC) and regarded as a prognostic value of outcomes in cardiopulmonary resuscitation (CPR). This study was to investigate changes of PETCO2 during CPR in rats with ventricular fibrillation (VF) versus asphyxial cardiac arrest.

METHODS

Sixty-two male Sprague-Dawley (SD) rats were randomly divided into an asphyxial group (n=32) and a VF group (n=30). PETCO2 was measured during CPR from a 6-minute period of VF or asphyxial cardiac arrest.

RESULTS

The initial values of PETCO2 immediately after PC in the VF group were significantly lower than those in the asphyxial group (12.8±4.87 mmHg vs. 49.2±8.13 mmHg, P=0.000). In the VF group, the values of PETCO2 after 6 minutes of PC were significantly higher in rats with return of spontaneous circulation (ROSC), compared with those in rats without ROSC (16.5±3.07 mmHg vs. 13.2±2.62 mmHg, P=0.004). In the asphyxial group, the values of PETCO2 after 2 minutes of PC in rats with ROSC were significantly higher than those in rats without ROSC (20.8±3.24 mmHg vs. 13.9±1.50 mmHg, P=0.000). Receiver operator characteristic (ROC) curves of PETCO2 showed significant sensitivity and specificity for predicting ROSC in VF versus asphyxial cardiac arrest.

CONCLUSIONS

The initial values of PETCO2 immediately after CPR may be helpful in differentiating the causes of cardiac arrest. Changes of PETCO2 during CPR can predict outcomes of CPR.

Systematic Review and Meta-Analysis of End-Tidal Carbon Dioxide Values Associated With Return of Spontaneous Circulation During Cardiopulmonary Resuscitation

Objective:

End-tidal carbon dioxide (ETCO2) measurements during cardiopulmonary resuscitation (CPR) reflect variable cardiac output over time, and low values have been associated with decreased survival. The goals of this review are to confirm and quantify this relationship and to determine the mean ETCO2 value among patients with return of spontaneous circulation (ROSC) as an initial step toward determining an appropriate target for intervention during resuscitation in the absence of prospective data.

Data Sources and Study Selection:

The PubMed database was searched for the key words “end-tidal carbon dioxide” or “capnometry” or “capnography” and “resuscitation” or “return of spontaneous circulation.” Randomized controlled trials, cohort studies, or case–control studies that reported ETCO2 values for participants with and without ROSC were included.

Data Extraction and Synthesis:

Twenty-seven studies met the inclusion criteria for qualitative synthesis. Twenty studies were included in determination of average ETCO2 values. The mean ETCO2 in participants with ROSC was 25.8 ± 9.8 mm Hg versus 13.1 ± 8.2 mm Hg ( P = .001) in those without ROSC. Nineteen studies were included in a meta-analysis. The mean difference in ETCO2 was 12.7 mm Hg (95% confidence interval: 10.3-15.1) between participants with and without ROSC ( P < .001). The mean difference in ETCO2 was not modified by the receipt of sodium bicarbonate, uncontrolled minute ventilation, or era of resuscitation guidelines. The overall quality of data by Grades of Recommendations, Assessment, Development and Evaluation criteria is very low, but no prospective data are currently available.

Conclusions:

Participants with ROSC after CPR have statistically higher levels of ETCO2. The average ETCO2 level of 25 mm Hg in participants with ROSC is notably higher than the threshold of 10 to 20 mm Hg to improve delivery of chest compressions. The ETCO2 goals during resuscitation may be higher than previously suggested and further investigation into appropriate targets during resuscitation is needed to diminish morbidity and mortality after cardiorespiratory arrest.

Year in review 2011: Critical Care--Out-of-hospital cardiac arrest and trauma

In 2011, numerous studies were published in Critical Care focusing on out-of-hospital cardiac arrest, cardiopulmonary resuscitation, trauma, and some related airway, respiratory, and response time factors. In this review, we summarize several of these studies, including those that brought forth advances in therapies for the post-resuscitative period. These advances involved hypothesis-generating concepts in therapeutic hypothermia as well as the impact of early percutaneous coronary artery interventions and the potential utility of extracorporeal life support after cardiac arrest. There were also articles pertaining to the importance of timing in prehospital airway management, the outcome impact of hyperoxia, and the timing of end-tidal carbon dioxide measurements to predict futility in cardiac arrest resuscitation. In other articles, additional perspectives were provided on the classic correlations between emergency medical service response intervals and outcomes.