Efficacy Of Chest Compressions Research Articles

Does the use of BariBoard™ improve adequacy of chest compressions in morbid obesity? A pilot study using a simulation model

BackgroundObesity is a growing health problem worldwide. Morbid obesity has been associated with significant barriers to effective thoracic cage compression during cardiopulmonary resuscitation. ObjectiveThe BariBoard™ purports to improve adequacy of chest compressions in morbidly obese patients. This study uses a simulation model to evaluate this. MethodsThis was a prospective blinded randomised-controlled crossover pilot trial using a simulation model of obesity. Participants, recruited from hospital departments and prehospital services, performed 2 minutes of continuous compressions on mannequins modified to emulate a morbidly obese patient. Participants were randomised by coin toss to a sequence of either control/intervention or intervention/control, with the BariBoard™ in the intervention arm. Accelerometers measured chest wall movement during compressions. The primary endpoint was a composite measure of compression adequacy (rate, depth, and recoil). Secondary endpoints comprised the individual components of the composite outcome, as both dichotomous outcomes (adequate vs. inadequate) and continuous variables. All endpoints were adjusted for potential confounders. ResultsOf 205 participants recruited, 201 were analysed. There was a significant difference in the primary outcome between the control and intervention arms (13.4% vs. 4.5%, respectively, p = 0.001) and between the control and intervention arms for the secondary endpoints of adequate compression depth (31.3% vs. 15.9%, p < 0.001) and recoil (63.7% vs. 41.3%, p < 0.001). After adjustment for confounders and interactions, there was no difference in overall efficacy (odds ratio: 0.62, 95% confidence interval: 0.20–1.90, p = 0.40). ConclusionThis pilot study describes the successful assessment of a device using a simulation model of obesity. Within these constraints and after adjustment for confounders, use of the BariBoard ™ did not improve efficacy of chest compressions.

Chest compression efficacy of child resuscitators

Background: Chest compression efficacy determines blood flow in cardiopulmonary resuscitation (CPR) and relies on body mechanics, so resuscitator weight matters. Individuals of insufficient weight are incapable of generating a sufficient downward chest compression force using traditional methods. Aims: This study investigated how a resuscitator's weight affects chest compression efficacy, determined the minimum weight required to perform chest compressions and, for children and adults below this minimum weight, examine alternate means to perform chest compressions. Methods: Volunteers aged 8 years and above were enrolled to perform video-recorded, music-facilitated, compression-only CPR on an audible click-confirming manikin for 2 minutes, following brief training. Subjects who failed this proceeded to alternate modalities: chest compressions by jumping on the lower sternum; and squat-bouncing (bouncing the buttocks on the chest). These methods were assessed via video review. Findings: There were 57 subjects. The 30 subjects above 40kg were all able to complete nearly 200 compressions in 2 minutes. Success rates declined in those who weighed less than 40kg. Below 30 kg, only one subject (29.9 kg weight) out of 14 could achieve 200 effective compressions. Nearly all of the 23 subjects who could not perform conventional chest compressions were able to achieve effective chest compressions using alternate methods. Conclusion: A weight below 40kg resulted in a declining ability to perform standard chest compressions effectively. For small resuscitators, the jumping and squat-bouncing methods resulted in sufficient compressions most of the time; however, chest recoil and injuries are concerns.

Efficacy of Chest Compressions Performed on Patients in Dental Chairs Versus on the Floor.

This study aimed to investigate the characteristics of chest compressions performed in dental chairs (DCs) with 2 different structural support designs and on the floor. This randomized prospective study was conducted to compare the effectiveness of chest compressions (rate and depth) using a feedback device and a manikin reporting system. The mean anterior chest wall motion measurements captured using the feedback device were significantly increased in the DCs than on the floor, whereas the percentage of net chest compression depths ≥5 cm as measured using the manikin reporting system were significantly decreased in the DCs than on the floor. These findings suggest that cardiopulmonary resuscitation performed in a DC without the use of a supporting stool or stiff backboard is not likely to be effective even if a DC design that incorporates a supportive steel column is utilized.

Kardiopulmonalna reanimacija u položaju na trbuhu

Cardiopulmonary resuscitation (CPR) is a series of life-saving procedures aimed at restoring and maintaining the functions of breathing and circulation in patients suffering from cardio-respiratory arrest. Old and new CPR guidelines assume that the patient is lying on the back, on a hard and stable surface. The prone position where the patient is lying on the stomach is often used in the operating room to enable an easier approach to the operative field and in intensive care units (ICU) to enable better oxygenation for patients in advanced stages of hypoxic respiratory insufficiency. During the COVID-19 pandemic, patients suffering from the infection are often treated in the prone position. Should cardiac arrest occur, it is necessary to initiate high-quality chest compressions and early defibrillation as soon as possible for the patient to have the best chance of survival. Current guidelines stipulate that CPR should be initiated immediately, even in the prone position, and kept up until conditions are met for the patient to be turned over onto the back. It is recommended to place hands on the patient's back at the level of the T7-T10 vertebrae and perform chest compressions with the usual strength and velocity (5-6 cm deep, 2 compressions per second). For defibrillation, self-adhesive disposable electrodes should be placed in an anterior-posterior or a bi-axillary position. Sternal counterpressure could increase the efficacy of chest compressions. Educating health workers to perform this CPR technique and using it in selected patients can increase survival.

Transesophageal echocardiography in patients with cardiac arrest: from high-quality chest compression to effective resuscitation.

Survival after cardiac arrest depends on prompt and effective cardiopulmonary resuscitation (CPR). Transesophageal echocardiography (TEE) can be applied to evaluate the effectiveness of chest compression-decompression maneuvers in the setting of cardiac arrest undergoing CPR. The efficacy of chest compression can be continuously assessed by TEE that can improve the effectiveness of CPR guiding the rescuer to optimize or correct chest compression and decompression by directly examining the movements of the cardiac walls and valve leaflets. The review describes how to perform TEE in the emergency setting of cardiopulmonary arrest, its advantages, and limitations, and ultimately propose an echo-guided approach to CPR.

352 Minimum Weight for Effective Chest Compressions and Alternative Methods for Smaller Rescuer Cardiopulmonary Resuscitation

The quality and quantity of chest compressions determine blood flow in cardiopulmonary resuscitation (CPR). Efficacious chest compressions rely on body mechanics such that the weight of the resuscitator matters; very small people have insufficient weight to generate sufficient downward chest compression force. The purpose of this study is to investigate how a resuscitator’s weight affects chest compression efficacy; and to determine the minimum weight required to perform adequate chest compressions. For those below this minimum weight (such as in children or smaller-bodied rescuers), we investigate alternative means to perform chest compressions. We enrolled volunteers age 8 years and above to perform video-recorded, compression-only CPR on an audible click-confirming chest compression manikin with background music to facilitate the chest compression rate for 2 minutes. All volunteers were provided with brief training, practice, and rest sessions prior to the recorded session. For all subjects, weight, height, age, sex, and CPR certification status were recorded. Subjects who failed to meet the criteria for efficacious chest compressions proceeded to two alternate chest compression modalities. In the first, subjects jumped up and down on the lower sternum while holding on to a horizontal support bar for balance. In the second, subjects used a squat-bounce method: sitting directly on the chest and using their legs, arms, and body weight to give compressions. Videos were reviewed to determine chest compression depth, rate, position, and recoil. An effective compression was one in which all four criteria were met. We enrolled 57 study subjects ranging from weights of 19 kg to 76 kg, which included 23 adults. Effective standard chest compressions declined at weights below 40 kg and no effective standard compression sessions occurred at weights below 29 kg (Figure 1). Adequate standard chest compressions declined at heights below 145 cm and no effective standard compression sessions were given at heights below 137 cm. For the 23 subjects who failed standard chest compressions, 19 (83%) were in the age group 8-10. There was no significant difference in the percentage of effective chest compressions with regard to sex in any method. Of the 23 subjects who failed, only 1 (4%) subject had taken a CPR certification course. Of the 23 subjects who failed standard chest compressions, 20 (87%) delivered effective compressions using the jumping modality. For 8 subjects who failed standard chest compressions, 7 (88%) delivered effective compressions using the squat-bouncing modality. Standard chest compression efficacy declines below 40 kg and cannot be performed adequately below 29 kg. For small resuscitators unable to perform standard compressions, jumping and squat-bouncing modalities resulted in sufficient chest compressions the majority of the time in this model; however, there are concerns regarding chest recoil and the potential for injury to the chest and abdomen.

The Efficacy of Chest Compressions in the Bell 407

ObjectiveThe Air Medical industry is fraught with obstacles to patient care and providers can recognize that several sub-groups of patients can provide very challenging scenarios while in flight. However, the patient experiencing cardiac arrest in flight is, by its very nature, one that poses the most severe risk to the patient and provider. This study seeks to explore the capability of a highly trained emergency medical provider to provide adequate chest compressions while in a Bell 407 helicopter. Methods59 participants were evaluated in two separate scenarios. Scenario A consisted of 2 rounds of of 200 chest compressions performed on a flat, uncrowded surface. Scenario B consisted of 200 chest compressions performed in the cabin of a Bell 407. Participants performed 2 rounds of 200 chest compressions. The results were then compared to each other and to the AHA 2010 CPR guidelines. ResultsThe findings of the study show that compressions performed in the aircraft do not meet AHA guidelines for chest compressions in regard to depth and duration of compressions. The deviation from guideline in regard to rate was found to be not statistically significant. ConclusionChest compressions performed in a Bell 407 helicopter do not meet AHA guidelines.

Does chest compression during cardiopulmonary resuscitation provide sufficient cerebral oxygenation?

Background/aim Some of the patients suffering from cardiac arrest (CA) remain in a chronic unconscious state in intensive care units (ICUs). The primary aim of this study was to evaluate the efficacy of chest compression (CC) on cerebral oxygenation during cardiopulmonary resuscitation (CPR). As a secondary goal, we attempted to determine the effects of regional cerebral oxygen saturation (rSO2) values on consciousness and the survival rate using the Full Outline of Unresponsiveness (FOUR) scoring method.Materials and methodsThis observational preliminary study was carried out with 20 patients with CA who were hospitalized in ICUs. The rSO2 values measured by near-infrared spectroscopy were recorded during CA. FOUR scoring was used to determine the neurological status, severity of disease, and degree of organ dysfunction in survivors.Results Return of spontaneous circulation (ROSC) was gained in 8 (40%) of 20 patients. Maximum rSO2 values were higher in survivors than in nonsurvivors (P = 0.005). The mean FOUR score before CA was 11.50 ± 0.8 in survivors, whereas this value was 7.87 ± 0.7 for 1 week after ROSC (P < 0.0001). There was a significant positive correlation between the minimum and mean rSO2 values and the mean 1-week FOUR scores in survivors (r = 0.811, r = 0.771 and P = 0.015, P = 0.025, respectively).Conclusion Our results suggest that the maximum rSO2 values affect ROSC while the minimum and mean rSO2 values affect the post-cardiac arrest neurological outcome.

General Management Principles of the Pregnant Woman

Pregnancy is a dynamic process that consists of profound physiological changes mediated by hormonal, mechanical, and circulatory pathways. Understanding of changes in physiology is essential for distinguishing abnormal and normal signs and symptoms in a pregnant patient. These physiological changes also have important pharmacotherapeutic considerations for a pregnant patient. Although there are limited data to guide decisions regarding medications and diagnostic procedures in pregnancy, a careful review of risks should be balanced with review of risk of withholding a medication or procedure. Interventional pulmonary procedures can be safely performed in pregnant women while keeping in mind the maternal anatomic and physiologic changes. Furthermore, management of a maternal cardiopulmonary arrest requires important modifications in patient positioning and intravenous access to ensure adequate efficacy of chest compressions, circulation, and airway management. This review will provide an overview of maternal physiologic changes with a focus on cardiopulmonary physiology, pharmacotherapeutic considerations, diagnostic and interventional pulmonary procedures during pregnancy, and cardiopulmonary resuscitation in pregnancy.

An investigation of thrust, depth and the impedance cardiogram as measures of cardiopulmonary resuscitation efficacy in a porcine model of cardiac arrest

ObjectiveOptimising the depth and rate of applied chest compressions following out of hospital cardiac arrest is crucial in maintaining end organ perfusion and improving survival. The impedance cardiogram (ICG) measured via defibrillator pads produces a characteristic waveform during chest compressions with the potential to provide feedback on cardiopulmonary resuscitation (CPR) and enhance performance. The objective of this pre-clinical study was to investigate the relationship between mechanical and physiological markers of CPR efficacy in a porcine model and examine the strength of correlation between the ICG amplitude, compression depth and end-tidal CO2 (ETCO2). MethodsTwo experiments were performed using 24 swine (12 per experiment). For experiment 1, ventricular fibrillation (VF) was induced and mechanical CPR commenced at varying thrusts (0–60kg) for 2min intervals. Chest compression depth was recorded using a Philips QCPR device with additional recording of invasive physiological parameters: systolic blood pressure, ETCO2, cardiac output and carotid flow. For experiment 2, VF was induced and mechanical CPR commenced at varying depths (0–5cm) for 2min intervals. The ICG was recorded via defibrillator pads attached to the animal's sternum and connected to a Heartsine 500P defibrillator. ICG amplitude, chest compression depth, systolic blood pressure and ETCO2 were recorded during each cycle. In both experiments the within-animal correlation between the measured parameters was assessed using a mixed effect model. ResultsIn experiment 1 moderate within-animal correlations were observed between physiological parameters and compression depth (r=0.69–0.77) and thrust (r=0.66–0.82). A moderate correlation was observed between compression depth and thrust (r=0.75). In experiment 2 a strong within-animal correlation and moderate overall correlations were observed between ICG amplitude and compression depth (r=0.89, r=0.79) and ETCO2 (r=0.85, r=0.64). ConclusionIn this porcine model of induced cardiac arrest moderate within animal correlations were observed between mechanical and physiological markers of chest compression efficacy demonstrating the challenge in utilising a single mechanical metric to quantify chest compression efficacy. ICG amplitude demonstrated strong within animal correlations with compression depth and ETCO2 suggesting its potential utility to provide CPR feedback in the out of hospital setting to improve performance.

The Effect of the Use of a Stabilizer and Different Height Settings on the Stability of the Dental Chair when Performing High-Quality Chest Compressions

Background/Aim: In the case of sudden cardiopulmonary arrest (CPA) in a patient in a dental practice, dental professionals have to perform cardiopulmonary resuscitation (CPR) in the dental chair. However, not all dental chairs are stable enough for performing chest compressions, as some do not contain steady support under the backrest. We investigated methods for stabilizing the dental chair to increase the efficacy of chest compressions performed in the chair. Materials and Methods: Chest compressions (with a depth of 5.0 to 6.0 cm) were performed on a CPR manikin that was laid on the backrest of a dental chair. The movement of the chest of the manikin and the displacement of the backrest caused by the chest compressions were recorded as video data, and the mean amplitude of the movement of the backrest at each compression depth was analyzed. We investigated the effect of three different height settings of the dental chair and the use of a round stool as a stabilizer under the backrest on the stability of the dental chair during CPR. Results: Differences in the height settings of the dental chair did not significantly affect the vertical movement of the backrest caused by chest compressions. The mean amplitudes of the movements of the backrest with and without a stabilizer were 1.99±0.74 cm and 0.43±0.18 cm, respectively. Conclusion: The placement of a round stool as a stabilizer under the backrest of a dental chair might increase the effectiveness of chest compressions.

Abstract 149: Zoniporide Combined with α-Methylnorepinephrine Promotes Greater Hemodynamic Stability than Either Agent Alone During Chest Compression in Rats

Background: We have reported in animal models of cardiac arrest that sodium hydrogen exchanger-1 (NHE-1) inhibition - by attenuating reperfusion injury - helps preserve left ventricular distensibility yielding higher forward blood flows during chest compression. Others have reported that α-methylnorepinephrine (α-MNE) - a selective peripheral α2-adrenoreceptor agonist - is superior to epinephrine given its lack of β-agonist effect that intensifies myocardial ischemia. We examined in a rat model of VF the effects of combining the NHE-1 inhibitor zoniporide (ZNP) with α-MNE during CPR, expecting to elicit a vasopressor effect (α-MNE) that is better maintained over time because of ZNP. Methods: VF was electrically induced in 32 male retired breeder Sprague-Dawley rats and left untreated for 8 minutes. Chest compression was then initiated, gradually increasing the depth of compression (maximum 17 mm) to attain an aortic diastolic pressure of 28 mmHg by the end of minute 2, maintaining such level for the remaining 6 minutes of chest compression, time at which defibrillation was attempted. The rats were randomized 1:1:1:1 to receive a 3 mg/kg bolus of ZNP or 0.9% NaCl before starting chest compression and a 100 μg/kg bolus of α-MNE or its vehicle at minute 2 of chest compression with the investigators blind to the assignment. Results: The ratio between the aortic diastolic pressure and depth of compression (Figure) was higher - as expected - in rats that received α-MNE(+) given its vasopressor effect. The effect, however, was not maintained and declined over time; but to a significantly lesser degree in rats that also received ZNP; i.e., α-MNE(+)/ZNP(+) group. Conclusions: The findings support a favorable interaction between α-MNE and ZNP; the first prompting needed peripheral vasoconstriction - likely with less concomitant myocardial injury - and the latter preserving left ventricular distensibility, which combined enhance the hemodynamic efficacy of chest compression.

External cardiac compression during cardiopulmonary resuscitation of patients with left ventricular assist devices.

A best evidence topic was written according to a structured protocol to determine whether there is evidence that cardiopulmonary resuscitation (CPR) by compressing the chest is safe and effective in patients with left ventricular assist devices (LVADs). Manufacturers warn of a possible risk of device dislodgement if the chest is compressed. AMED, EMBASE, MEDLINE, BNI and CINAHL were searched from inception to March 2014. Animal studies, case reports, case series, case-control studies, randomized controlled studies and systematic reviews were eligible for inclusion. Opinion articles with no reference to data were excluded. Of 45 unique results, 3 articles merited inclusion. A total of 10 patients with LVADs received chest compression during resuscitation. There was no report of device dislodgement as judged by postarrest flow rate, autopsy and resumption of effective circulation and/or neurological function. The longest duration of chest compression was 150 min. However, there are no comparisons of the efficacy of chest compressions relative to alternative means of external CPR, such as abdominal-only compressions. The absence of high-quality data precludes definitive recommendation of any particular form of CPR, in patients with LVADs. However, data identified suggest that chest compression is not as unsafe as previously thought. The efficacy of chest compressions in this patient population has not yet been investigated. Further research is required to address both the safety and efficacy of chest compressions in this population. Urgent presentation and publication of further evidence will inform future guidance.

Efficacy of Chest Compressions Directed by End‐Tidal CO 2 Feedback in a Pediatric Resuscitation Model of Basic Life Support

BackgroundEnd‐tidal carbon dioxide (ETCO2) correlates with systemic blood flow and resuscitation rate during cardiopulmonary resuscitation (CPR) and may potentially direct chest compression performance. We compared ETCO2‐directed chest compressions with chest compressions optimized to pediatric basic life support guidelines in an infant swine model to determine the effect on rate of return of spontaneous circulation (ROSC).Methods and ResultsForty 2‐kg piglets underwent general anesthesia, tracheostomy, placement of vascular catheters, ventricular fibrillation, and 90 seconds of no‐flow before receiving 10 or 12 minutes of pediatric basic life support. In the optimized group, chest compressions were optimized by marker, video, and verbal feedback to obtain American Heart Association‐recommended depth and rate. In the ETCO2‐directed group, compression depth, rate, and hand position were modified to obtain a maximal ETCO2 without video or verbal feedback. After the interval of pediatric basic life support, external defibrillation and intravenous epinephrine were administered for another 10 minutes of CPR or until ROSC. Mean ETCO2 at 10 minutes of CPR was 22.7±7.8 mm Hg in the optimized group (n=20) and 28.5±7.0 mm Hg in the ETCO2‐directed group (n=20; P=0.02). Despite higher ETCO2 and mean arterial pressure in the latter group, ROSC rates were similar: 13 of 20 (65%; optimized) and 14 of 20 (70%; ETCO2 directed). The best predictor of ROSC was systemic perfusion pressure. Defibrillation attempts, epinephrine doses required, and CPR‐related injuries were similar between groups.ConclusionsThe use of ETCO2‐directed chest compressions is a novel guided approach to resuscitation that can be as effective as standard CPR optimized with marker, video, and verbal feedback.

Most Important Outcomes Research Papers on Cardiac Arrest and Cardiopulmonary Resuscitation

Cardiac arrest is a common and treatable cause of death and disability. Each year ≈424 000 people experience emergency medical services (EMS)-assessed out-of-hospital cardiac arrest (OHCA) in the United States.1 The actual burden of OHCA is likely significantly higher because a substantial number go unassessed. In a prospective analysis of deaths in a US county, 5.6% of annual mortality was attributable to cardiac arrest.2 Many patients who suffer OHCA do not receive prompt cardiopulmonary resuscitation (CPR). Among those who receive CPR, a large number do not survive because of an inability to restore spontaneous circulation, or anoxic cerebral injury even after restoration of circulation. Nevertheless, when timely interventions are provided, a small proportion of patients (10.4% of all EMS-treated OHCA) recover to resume normal lives. The key therapeutic interventions that make the difference between life and death, metaphorically characterized as the 5 links in a chain of survival by the American Heart Association, include: (1) immediate recognition of cardiac arrest and activation of the EMS, (2) early CPR with emphasis on chest compression, (3) rapid defibrillation, (4) effective advanced life support, and (5) integrated postcardiac arrest care.3 Resuscitation science has undergone major advances since the origins of modern CPR >50 years ago.4 The field continues to be dynamic with emergence of new therapies such as therapeutic hypothermia5 and improvements in systems of care. However, many questions remain on issues such as optimum compression rate, efficacy of chest compression only CPR (CCCPR), dispatcher-assisted CPR, and benefits of postresuscitation measures such as hypothermia. A critical challenge also lies in the translation of resuscitation science into practice. To improve outcomes, each of the links in the chain of survival needs to be executed promptly and effectively. There remain several lacunae, which need to be overcome to develop an …

Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation

OBJECTIVE:To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation.METHODS:This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected.RESULTS:We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005).CONCLUSIONS:In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/])

Abstract 279: Real-time Cerebral Hemoglobin Concentration Changes From NIRS; a Valid Evaluation Method for Quality CPR Chest Compression in Out-of-Hospital Cardiac Arrest

Background: Near-Infrared Spectroscopy (NIRS) is a non-invasive real-time measurement device capable of monitoring the cerebral perfusion volume and may potentially represent the efficacy of chest compression. Introduction: NIRS assesses cerebral hemoglobin concentration changes ([[Unable to Display Character: ⊿]]cHb) independently of pulse by utilizing adhesive sensors that are placed on the forehead where [[Unable to Display Character: ⊿]]cHb measurements are evaluated within the segment of cerebral tissue analyzed. [[Unable to Display Character: ⊿]]cHb waveforms are displayed real-time and reflect chest compression quality which we defined as compressions of adequate depth capable to increase cerebral perfusion manifesting as waveforms on monitor. We set out to identify whether a relationship between [[Unable to Display Character: ⊿]]cHb and quality chest compressions could be determined with NIRS. Method: We prospectively enrolled eight out-of-hospital cardiac arrest (OHCA) patients admitted to our ED. The exclusion criteria included trauma and age &lt; 15. Seven (87.5%) underwent both [[Unable to Display Character: ⊿]]cHb evaluation with the NIRO200NX (Hamamatsu Photonics) using NIRS and compression depth evaluation with the MRx-QCPR (Philips Healthcare). Each 2-minute CPR session is administered by one same operator and may be relegated in-between CPR sessions. From the whole resuscitation process, we randomly selected from 3 CPR sessions over 100 [[Unable to Display Character: ⊿]]cHb waveforms for every subject (~30 waveforms per session) and investigated correlations between the selected [[Unable to Display Character: ⊿]]cHb waveforms amplitudes and the depth of their respective chest compression. Results: 2 (29%) were strongly correlated. Within each single 2-minute CPR session, significant correlation was observed, whereas the totality of three CPR sessions demonstrated poor correlations attributable to several CPR manipulators. Conclusion: Strong correlation appears to exist between [[Unable to Display Character: ⊿]]cHb waveforms and chest compression depth. NIRS can evaluate in real-time[[Unable to Display Character: ⊿]]cHb waveform and may potentially serve as an index to evaluate quality CPR chest compression.

Peter Nagele, M.D., Recipient of the 2012 Presidential Scholar Award

Peter Nagele, M.D., Recipient of the 2012 Presidential Scholar Award

Abstract 287: Erythropoietin Enables Mitochondria to Preserve Oxidative Phosphorylation Under Conditions of Calcium Overload and Oxidative Stress

Introduction: We previously reported in rats that a single bolus dose of erythropoietin (Epo) given at the start of CPR enhanced, within minutes, the efficacy of chest compression. The effect was attributed to attenuation of reductions in left ventricular distensibility; an effect previously linked to preservation of mitochondrial bioenergetic function. Hypothesis: We now investigated whether Epo could enable mitochondria to maintain oxidative phosphorylation under conditions of calcium overload and oxidative stress, which are central to injury caused by ischemia and reperfusion. Methods: Mitochondria were isolated from the left ventricle of hearts harvested from groups of rats (n=3) that received during spontaneous circulation no Epo or received Epo (5,000 U/kg) in bolus dose into the right atrium at 60, 240, and 480 seconds before harvest. Separate aliquots of mitochondria were subjected to incremental concentrations of calcium (1.5, 12.5, and 25 µM free calcium) or tert-butyl hydroperoxide (250 and 5000 µM). Phosphate:oxygen (P:O) ratios were then measured in a respiration chamber (MT 200, Mitocell, Strathkelvin Instruments). Results: Epo, in a time dependent manner, prevented reductions in P:O ratios observed when mitochondria were exposed to incremental concentrations of calcium or tert-butyl hydroperoxide (Table). Conclusions: Preservation of left ventricular myocardial distensibility could partly result from a favorable effect of Epo enabling mitochondria to resist injury caused by calcium overload and oxidative stress, and within a response time sufficiently rapid to favorably impact cardiac resuscitation.

Abstract 54: The Impedance Cardiogram as an Indicator of Chest Compression Efficacy During Cardiopulmonary Resuscitation in a Porcine Model: Correlation with Physiological Parameters and Comparison with Compression Depth and Thrust

Introduction The 2010 AHA resuscitation guidelines re-emphasised the importance of chest compressions as the cornerstone of effective CPR. In an attempt to improve chest compression efficacy numerous CPR feedback devices have been developed and have demonstrated their utility in improving guideline compliant CPR but not patient outcomes. The impedance cardiogram (ICG) provides a non-invasive measure of haemodynamic status and has been investigated as an additional method of improving CPR. Objectives The purpose of this study was to examine the relationship between chest compression thrust, depth and ICG amplitude during CPR and establish their correlation with invasive physiological measurements. Materials and methods Ethical approval for this study was granted by the Northern Ireland Home Office. A total of 12 porcine models were used weighing mean 31kg. Anaesthesia was achieved with intravenous propofol and inhaled isoflourane. Ventricular fibrillation was induced using a pacing wire inserted into the right ventricle. CPR was administered using the HLR-201®, Michigan Instruments. The Impedance Cardiogram (ICG) was recorded via 2 standard defibrillation electrodes. Depth (cm), thrust (kg), end-tidal CO 2 (kPa), systolic blood pressure (mmHg), carotid flow (ml/min) and cardiac output (L/min) were measured at 2 minute intervals for each model. Results There is a strong correlation between ICG amplitude and physiological parameters, comparable to correlations achieved with compression depth and thrust. (Table 1) Table 1: Summary of correlations between physiological parameters and ICG, compression depth and thrust during CPR Conclusions The ICG amplitude provides an additional measurement of CPR efficacy with physiological correlations comparable to both chest compression thrust and depth. This non-invasive measurement could be exploited in the development of new CPR feedback algorithms for automated external defibrillators.