Systematic review of the mechanisms driving effective blood flow during adult CPR

Real-time feedback on chest compression efficacy by hands-free carotid Doppler in a porcine model

Aim

Current guidelines for cardiopulmonary resuscitation (CPR) recommend a one-size-fits-all approach in relation to the positioning of chest compressions. We recently developed RescueDoppler, a hands-free Doppler ultrasound device for continuous monitoring of carotid blood flow velocity during CPR. The aim of the present study is to investigate whether RescueDoppler via real-time hemodynamic feedback, could identify both optimal and suboptimal compression positions.

Methods

In this model of animal cardiac arrest, we induced ventricular fibrillation in five domestic pigs. Manual chest compressions were performed for ten seconds at three different positions on the sternum in random order and repeated six times. We analysed Time Average Velocity (TAV) with chest compression position as a fixed effect and animal, position, and sequential time within animals as random effects. Furthermore, we compared TAV to invasive blood pressure from the contralateral carotid artery.

Results

We were able to detect changes in TAV when altering positions. The positions with the highest (range 19 to 48 cm/s) and lowest (6-25 cm/s) TAV were identified in all animals, with corresponding peak pressure 50-81 mmHg, and 46-64 mmHg, respectively. Blood flow velocity was, on average, highest at the middle position (TAV 33 cm/s), but with significant variability between animals (SD 2.8) and positions within the same animal (SD 9.3).

Conclusion

RescueDoppler detected TAV changes during CPR with alternating chest compression positions, identifying the position yielding maximal TAV. Future clinical studies should investigate if RescueDoppler can be used as a real-time hemodynamical feedback device to guide compression position.

COMPARISON BETWEEN ACTIVE ABDOMINAL COMPRESSION-DECOMPRESSION CARDIOPULMONARY RESUSCITATION AND STANDARD CARDIOPULMONARY RESUSCITATION IN ASPHYCTIC CARDIAC ARREST RATS WITH MULTIPLE RIB FRACTURES

ABSTRACT

Background: Active abdominal compression-decompression cardiopulmonary resuscitation (AACD-CPR) is potentially more effective for cardiac arrest (CA) with multiple rib fractures. However, its effect on survival rates and neurological outcomes remains unknown. This study aimed to assess if AACD-CPR improves survival rates and neurological outcomes in a rat model of asphyctic CA with multiple rib fractures. Methods: Adult male Sprague-Dawley rats were randomized into three groups-AACD group (n = 15), standard cardiopulmonary resuscitation (STD-CPR) group (n = 15), and sham group (n = 10)-after bilateral rib fractures were surgically created and endotracheal intubation was performed. AACD-CPR and STD-CPR groups underwent 8 min of asphyxia followed by different CPR techniques. The sham group had venous catheterization only. Physiological variables and arterial blood gases were recorded at baseline and during a 4-h monitoring period. Neurological deficit scores (NDSs) and cumulative survival rates were assessed at 24, 48, and 72 h. NDS, serum biomarkers, and hippocampal neuron analysis were used to evaluate neurological outcomes. Results: No statistical differences were observed in the return of spontaneous circulation (ROSC), 24-, 48-, and 72-h survival rates between the AACD-CPR and STD-CPR groups. AACD-CPR rats had lower serum levels of neuron-specific enolase and S100B at 72 h post-ROSC, and higher NDS at 72 h post-ROSC compared with STD-CPR animals. Cellular morphology analysis, hematoxylin and eosin staining, and TUNEL/DAPI assays showed more viable neurons and fewer apoptotic neurons in the AACD-CPR group than in the STD-CPR group. Conclusions: AACD-CPR can achieve similar survival rates and better neurological outcome after asphyxial CA in rats with multiple rib fractures when compared with STD-CPR.

Ventilatory improvement with mechanical ventilator versus bag in non-traumatic out-of-hospital cardiac arrest: SYMEVECA study, phase 1

AIM

To analyze differences in ventilatory parameters and outcome with different ventilatory methods during CPR.

METHODS

Pragmatic prospective quasi-experimental study in out-of-hospital urban environment. Patients over 18 years of age in non-traumatic cardiac arrest, attended by an emergency medical service between April 2021 and September 2022, were included. Two groups were compared according to the ventilatory method: mechanical ventilator (IPPV, tidal volume 7 ml/kg, frequency 10-12 bpm) or manual resuscitator bag. The main variables of interest are those of gasometry performed 15 minutes after intubation or when spontaneous circulation is recovered and final outcome. Patients were followed up to hospital discharge.

RESULTS

Of the 359 patients attended, 150 were included (71 in IPPV and 79 with a bag). In patients with arterial blood gases, pCO2 was 67.8 ± 21.1 in the IPPV group vs 95.9 ± 39.0 mmHg in the bag group (p = 0.006) and pH was 7.00 ± 0.18 vs 6.92 ± 0.18 (p = 0.18). With a venous sample, the pCO2 was 68.1 ± 18.9 vs 89.5 ± 26.5 mmHg (p < 0.001) and the pH was 7.03 ± 0.15 vs 6.94 ± 0.17 (p = 0.005), respectively. Survival with CPC 1-2 to hospital discharge was 15.6% with IPPV and 11.3% with bag (p = 0.44).

CONCLUSION

The use of a mechanical ventilator in IPPV was associated with a better ventilatory status during CPR compared to the use of the bag, without conclusive data regarding its clinical repercussion with the sample collected.

Do patient outcomes differ when the trauma team leader is a surgeon or non-surgeon? A multicentre cohort study

PURPOSE

Trauma team leaders (TTLs) have traditionally been general surgeons; however, some trauma centres use a mixed model of care where both surgeons and non-surgeons (primarily emergency physicians) perform this role. The objective of this multicentre study was to provide a well-powered study to determine if TTL specialty is associated with mortality among major trauma patients.

METHODS

Data were collected from provincial trauma registries at six level 1 trauma centres across Canada over a 10-year period. We included adult trauma patients (age ≥ 18 yrs) who triggered the highest-level trauma activation. The primary outcome was the difference in risk-adjusted in-hospital mortality for trauma patients receiving initial care from a surgeon versus a non-surgeon TTL.

RESULTS

Overall, 12,961 major trauma patients were included in the analysis. Initial treatment was provided by a surgeon TTL in 57.8% (n = 7513) of cases, while 42.2% (n = 5448) of patients were treated by a non-surgeon TTL. Unadjusted mortality occurred in 11.6% of patients in the surgeon TTL group and 12.7% of patients in the non-surgeon TTL group (OR 0.87, 95% CI 0.78-0.98, p = 0.02). Risk-adjusted mortality was not significantly different between patients cared for by surgeon and non-surgeon TTLs (OR 0.92, 95% CI 0.80-1.06, p = 0.23). Furthermore, we did not observe differences in risk-adjusted mortality for any of the subgroups evaluated.

CONCLUSIONS

After risk adjustment, there was no difference in mortality between trauma patients treated by surgeon or non-surgeon TTLs. Our study supports emergency physicians performing the role of TTL at level 1 trauma centres.

The Influence of Ultra-Low Tidal Volume Ventilation during Cardiopulmonary Resuscitation on Renal and Hepatic End-Organ Damage in a Porcine Model

The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) has eluded scientists for years. This porcine study aims to validate the hypothesis that ultra-low tidal volume ventilation (tidal volume 2–3 mL kg−1; ULTVV) minimizes renal and hepatic end-organ damage when compared to standard intermittent positive pressure ventilation (tidal volume 8–10 mL kg−1; IPPV) during CPR. After induced ventricular fibrillation, the animals were ventilated using an established CPR protocol. Upon return of spontaneous circulation (ROSC), the follow-up was 20 h. After sacrifice, kidney and liver samples were harvested and analyzed histopathologically using an Endothelial, Glomerular, Tubular, and Interstitial (EGTI) scoring system for the kidney and a newly developed scoring system for the liver. Of 69 animals, 5 in the IPPV group and 6 in the ULTVV group achieved sustained ROSC and were enlisted, while 4 served as the sham group. Creatinine clearance was significantly lower in the IPPV-group than in the sham group (p < 0.001). The total EGTI score was significantly higher for ULTVV than for the sham group (p = 0.038). Aminotransferase levels and liver score showed no significant difference between the intervention groups. ULTVV may be advantageous when compared to standard ventilation during CPR in the short-term ROSC follow-up period.

Clinical outcomes following out-of-hospital cardiac arrest: The minute-by-minute impact of bystander cardiopulmonary resuscitation

AIMS

The time-dependent prognostic role of bystander cardiopulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) patients has not been described with great precision, especially for neurologic outcomes. Our objective was to assess the association between bystander CPR, emergency medical service (EMS) response time, and OHCA patients' outcomes.

METHODS

This cohort study used the Resuscitation Outcomes Consortium Cardiac Epidemiologic Registries. Bystander-witnessed adult OHCA treated by EMS were included. The primary outcome was survival to hospital discharge and secondary outcome was survival with a good neurologic outcome (modified Rankin scale 0-2). Multivariable logistic regression models were used to assess the associations and interactions between bystander CPR, EMS response time and clinical outcomes.

RESULTS

Out of 229,637 patients, 41,012 were included (18,867 [46.0%] without bystander CPR and 22,145 [54.0%] with bystander CPR). Bystander CPR was independently associated with higher survival (adjusted odds ratio [AOR] = 1.70 [95%CI 1.61-1.80]) and survival with a good neurologic outcome (AOR = 1.87 [95%CI 1.70-2.06]), while longer EMS response times were independently associated with lower survival to hospital discharge (each additional minute of EMS response time: AOR = 0.92 [95%CI 0.91-0.93], p < 0.001) and lower survival with a good neurologic outcome (AOR = 0.88 [95%CI 0.86-0.89], p < 0.001). There was no interaction between bystander CPR and EMS response time's association with survival (p = 0.12) and neurologic outcomes (p = 0.65).

CONCLUSIONS

Although bystander CPR is associated with an immediate increase in odds of survival and of good neurologic outcome for OHCA patients, it does not influence the negative association between longer EMS response time and survival and good neurologic outcome.

A prospective observational study on impact of epinephrine administration route on acute myocardial infarction patients with cardiac arrest in the catheterization laboratory (iCPR study)

BACKGROUND

Epinephrine is routinely utilized in cardiac arrest; however, it is unclear if the route of administration affects outcomes in acute myocardial infarction patients with cardiac arrest.

OBJECTIVES

To compare the efficacy of epinephrine administered via the peripheral intravenous (IV), central IV, and intracoronary (IC) routes.

METHODS

Prospective two-center pilot cohort study of acute myocardial infarction patients who suffered cardiac arrest in the cardiac catheterization laboratory during percutaneous coronary intervention. We compared the outcomes of patients who received epinephrine via peripheral IV, central IV, or IC.

RESULTS

158 participants were enrolled, 48 (30.4%), 50 (31.6%), and 60 (38.0%) in the central IV, IC, and peripheral IV arms, respectively. Peripheral IV epinephrine administration route was associated with lower odds of achieving return of spontaneous circulation (ROSC, odds ratio = 0.14, 95% confidence interval = 0.05-0.36, p < 0.0001) compared with central IV and IC administration. (There was no difference between central IV and IC routes; p = 0.9343.) The odds of stent thrombosis were significantly higher with the IC route (IC vs. peripheral IV OR = 4.6, 95% CI = 1.5-14.3, p = 0.0094; IC vs. central IV OR = 6.0, 95% CI = 1.9-19.2, p = 0.0025). Post-ROSC neurologic outcomes were better for central IV and IC routes when compared with peripheral IV.

CONCLUSION

Epinephrine administration via central IV and IC routes was associated with a higher rate of ROSC and better neurologic outcomes compared with peripheral IV administration. IC administration was associated with a higher risk of stent thrombosis. Trial registration This trial is registered at NCT05253937 .

Quality Evaluation Algorithm for Chest Compressions Based on OpenPose Model

Aiming at the problems of the low evaluation efficiency of the existing traditional cardiopulmonary resuscitation (CPR) training mode and the considerable development of machine vision technology, a quality evaluation algorithm for chest compressions (CCs) based on the OpenPose human pose estimation (HPE) model is proposed. Firstly, five evaluation criteria are proposed based on major international CPR guidelines along with our experimental study on elbow straightness. Then, the OpenPose network is applied to obtain the coordinates of the key points of the human skeleton. The algorithm subsequently calculates the geometric angles and displacement of the selected joint key points using the detected coordinates. Finally, it determines whether the compression posture is standard, and it calculates the depth, frequency, position and chest rebound, which are the critical evaluation metrics of CCs. Experimental results show that the average accuracy of network behavior detection reaches 94.85%, and detection speed reaches 25 fps.

Performance of an automated ultrasound device in identifying and tracing the heart in porcine cardiac arrest

BACKGROUND

While intra-arrest echocardiography can be used to guide and monitor chest compression quality, it is not currently feasible on the scene of out-of-hospital cardiac arrests. Rapid and automated sonographic localization of the heart may provide first-responders guidance to an optimal area of compression without requiring them to interpret ultrasound images. In this proof-of-concept porcine study, we sought to describe the performance of an automated ultrasound device in correctly identifying and tracing the borders of the heart in three distinct states: pre-arrest, arrest, and late arrest.

METHODS

An automated ultrasound device (bladder scanner) was placed on the chests of 7 swine, along the left sternal border (4th-8th intercostal spaces). Scanner-generated images were recorded for each space during pre-arrest, arrest, and finally late arrest. 828 images of the LV and LV outflow tract were randomized and 150 (50/state) selected for analysis. Scanner tracings of the heart were then digitally obscured to facilitate tracing by expert reviewers who were blinded to the physiologic state. Reviewer tracings were compared to bladder scanner tracings; with concordance between these images determined via Sørensen-Dice index (SDI).

RESULTS

When compared to human reviewers, the bladder scanner was able to identify and trace the borders during cardiac arrest. The bladder scanner performed best at the time of arrest (SDI 0.900 ± 0.059). As resuscitation efforts continued and time from initial arrest increased, the scanner's performance decreased dramatically (SDI 0.597 ± 0.241 in late arrest).

CONCLUSION

An automated ultrasound device (bladder scanner) reliably traced porcine hearts during cardiac arrest. It is possible a device could be developed to indicate where compressions should be performed without requiring the operator to interpret ultrasound images. Further investigation into rapid, automated, sonographic localization of the heart to identify the area of compression in out-of-hospital cardiac arrest is warranted.

Rewarming With Closed Thoracic Lavage Following 3-h CPR at 27°C Failed to Reestablish a Perfusing Rhythm

Introduction: Previously, we showed that the cardiopulmonary resuscitation (CPR) for hypothermic cardiac arrest (HCA) maintained cardiac output (CO) and mean arterial pressure (MAP) to the same reduced level during normothermia (38°C) vs. hypothermia (27°C). In addition, at 27°C, the CPR for 3-h provided global O₂ delivery (DO₂) to support aerobic metabolism. The present study investigated if rewarming with closed thoracic lavage induces a perfusing rhythm after 3-h continuous CPR at 27°C.

Materials and Methods: Eight male pigs were anesthetized, and immersion-cooled. At 27°C, HCA was electrically induced, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed by combining closed thoracic lavage and continued CPR. Organ blood flow was measured using microspheres.

Results: After cooling with spontaneous circulation to 27°C, MAP and CO were initially reduced by 37 and 58% from baseline, respectively. By 15 min after the onset of CPR, MAP, and CO were further reduced by 58 and 77% from baseline, respectively, which remained unchanged throughout the rest of the 3-h period of CPR. During CPR at 27°C, DO₂ and O₂ extraction rate (VO₂) fell to critically low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. During rewarming with closed thoracic lavage, all animals displayed ventricular fibrillation, but only one animal could be electro-converted to restore a short-lived perfusing rhythm. Rewarming ended in circulatory collapse in all the animals at 38°C.

Conclusion: The CPR for 3-h at 27°C managed to sustain lower levels of CO and MAP sufficient to support global DO₂. Rewarming accidental hypothermia patients following prolonged CPR for HCA with closed thoracic lavage is not an alternative to rewarming by extra-corporeal life support as these patients are often in need of massive cardio-pulmonary support during as well as after rewarming.

Are treatment effects consistent with hypothesized mechanisms of action proposed for postoperative delirium interventions? Reanalysis of systematic reviews

Aim: Postoperative delirium (POD) is associated with increased morbidity and is poorly understood. The aim of this review was to identify putative mechanisms through re-analysis of randomized trials on treatment or prevention of POD. Materials & methods: A systematic review was performed to identify systematic reviews of treatments for POD. Constituent randomized controlled trials were identified, and interventions were grouped according to hypothesized mechanisms of action. Effects were meta-analyzed by hypothesized mechanism and timing of intervention. Results: A total of 116 randomized controlled trials described 47 individual interventions for POD, with nine mechanisms identified. The largest effects were observed for postoperative inflammation reduction, and preoperative reinforcement of sleep-wake cycle. Conclusion: This approach identifies treatments focused on mechanisms of action that may be front runners for future trials and interventions.

Assessment of chest compression interruptions during advanced cardiac life support

AIM

To identify potentially avoidable factors responsible for chest compression interruptions and to evaluate the influence of chest compression fraction on achieving return of spontaneous circulation and survival to hospital discharge.

METHODS

In this prospective observational study, each resuscitation managed by mobile medical teams from August 1st, 2016, to August 1st, 2018 was video recorded using a body-mounted GoPro camera. The duration of all chest compression interruptions was recorded and chest compression fraction was calculated. All actions causing an interruption of at least 10 s were analyzed.

RESULTS

Two hundred and six resuscitations of both in- and out-of-hospital cardiac arrest patients were analysed. In total 1867 chest compression interruptions were identified. Of these, 623 were longer than 10 s in which a total of 794 actions were performed. In 4.3% of the registered pauses, cardiopulmonary resuscitation was interrupted for more than 60 s. The most performed actions during prolonged interruptions were rhythm/pulse checks (51.6%), installation/use of mechanical chest compression devices (11.1%), cardiopulmonary resuscitation provider switches (6.7%) and ETT placements (6.2%). No statistically significant relationship was found between chest compression fraction and return of spontaneous circulation or survival.

CONCLUSION

The majority of chest compression interruptions during resuscitation were caused by prolonged rhythm checks, cardiopulmonary resuscitation provider switches, incorrect use of mechanical chest compression devices and ETT placement. No association was found between chest compression fraction and return of spontaneous circulation, nor an influence on survival. This was presumably caused by the high baseline chest compression fraction of >86%.

Cardiopulmonary Resuscitation With Mechanical Chest Compression Device During Percutaneous Coronary Intervention. A Case Report

Sudden cardiac death is a leading cause of death worldwide, whereby myocardial infarction is considered the most frequent underlying condition. Percutaneous coronary intervention (PCI) is an important component of post-resuscitation care, while uninterrupted high-quality chest compressions are key determinants in cardiopulmonary resuscitation (CPR). In our paper, we evaluate a case of a female patient who suffered aborted cardiac arrest due to myocardial infarction. The ambulance crew providing prehospital care for sudden cardiac arrest used a mechanical chest compression device during advanced CPR, which enabled them to deliver ongoing resuscitation during transfer to the PCI laboratory located 20 km away from the scene. Mechanical chest compressions were continued during the primary coronary intervention. The resuscitation, carried out for 2 h and 35 min, and the coronary intervention were successful, as evidenced by the return of spontaneous circulation and by the fact that, after a short rehabilitation, the patient was discharged home with a favorable neurological outcome. Our case can serve as an example for the effective and safe use of a mechanical compression device during primary coronary intervention.

Optimizing hemodynamic function during cardiopulmonary resuscitation

PURPOSE OF REVIEW

The purpose of this narrative review is to provide an update on hemodynamics during cardiopulmonary resuscitation (CPR) and to describe emerging therapies to optimize perfusion.

RECENT FINDINGS

Cadaver studies have shown large inter-individual variations in blood distribution and anatomical placement of the heart during chest compressions. Using advanced CT techniques the studies have demonstrated atrial and slight right ventricular compression, but no direct compression of the left ventricle. A hemodynamic-directed CPR strategy may overcome this by allowing individualized hand-placement, drug dosing, and compression rate and depth. Through animal studies and one clinical before-and-after study head-up CPR has shown promising results as a potential strategy to improve cerebral perfusion. Two studies have demonstrated that placement of an endovascular balloon occlusion in the aorta (REBOA) can be performed during ongoing CPR.

SUMMARY

Modern imaging techniques may help increase our understanding on the mechanism of forward flow during CPR. This could provide new information on how to optimize perfusion. Head-up CPR and the use of REBOA during CPR are novel methods that might improve cerebral perfusion during CPR; both techniques do, however, still await clinical testing.

A Novel Anatomic Landmark to Target the Left Ventricle During Chest Compressions in Cardiac Arrest

Background Resuscitation guidelines recommend that chest compressions be performed over the lower sternum. Current computed tomography and magnetic resonance imaging studies suggest that the current area of compression does not target the left ventricle (LV). Using transthoracic ultrasound, we sought to identify potential anatomic landmarks that would result in compressions over the LV in the majority of our study participants. Methodology We recruited 64 healthy men and women (over the age of 40) from the Simulated Patient Program at the University of Saskatchewan. Using ultrasound, we identified the LV and the associated surface anatomy in terms of intercostal space (ICS) and parasternal or mid-clavicular lines. We also collected biometric data including body mass index, chest circumference, and the corresponding inter-nipple line ICS. Results The LV was located along the left sternal border in 62 (96.9%) participants. The most frequent LV location was along the left sternal border at the sixth ICS in 26 (40.6%) participants, with 13 (20.3%) at the fifth and 10 (15.6%) participants at the seventh ICS. In two (3.1%) participants, the LV was found along the mid-clavicular zone at the fifth ICS. The area from the fifth to seventh ICS on the left sternal border, typically covered by an adult palm centered at the sixth ICS, overlaid 49 of 64 (76.6%, 95% confidence interval [CI]: 64.3-86.2%) identified LV locations. By comparison, centering the heel of the palm over the inter-nipple line at the left sternal border would cover the LV in 46 (71.9%, 95% CI: 59.2-82.4%) participants.  Conclusions A novel area of compression over the left sternal border at the inter-nipple line would result in compressions over the LV in nearly three-quarters of our study participants. Future research should investigate whether this proposed area of compression is applicable to a broader population including those with cardiac and thoracic disease.

An exploration of UK paramedics' experiences of cardiopulmonary resuscitation-induced consciousness

Introduction:

Consciousness may occur during cardiopulmonary resuscitation despite the absence of a palpable pulse. This phenomenon, known as CPR-Induced Consciousness (CPR-IC), was first described over three decades ago and there has been an increase in case reports describing it. However, there remains limited evidence in relation to the incidence of CPR-IC and to practitioners’ experiences of it.

Methods:

A mixed-methods, cross-sectional survey of paramedics who were registered with the Health and Care Professions Council (HCPC) and working in the United Kingdom (UK) at the time of the survey. Participants who had experienced CPR-IC were asked to provide details about the number of episodes, a description of how consciousness was manifested and whether or not it interfered with resuscitation.

Results:

293 eligible participants completed the study and 167 (57%) said that they had witnessed CPR-IC. Of those, over 56% reported that they had experienced it on at least two occasions. CPR-IC was deemed to interfere with resuscitation in nearly 50% of first experiences but this fell to around 31% by the third experience. The most common reasons for CPR-IC to interfere with resuscitation were: patient resisting clinical interventions, increased rhythm and pulse checks, distress, confusion and reluctance to perform CPR.

Conclusions:

The prevalence of CPR-IC in our study was similar to that in earlier studies; however, unlike the other studies, we did not define what constituted interfering CPR-IC. Our findings suggest that interference may be related as much to the exposure of the clinician to CPR-IC as to any specific characteristic of the phenomenon itself.

Use of a Simple Ultrasound Device to Identify the Optimal Area of Compression for Out-of-Hospital Cardiac Arrest

Background Despite automated defibrillation and compression-first resuscitation, out-of-hospital cardiac arrest (OHCA) survival remains low. Resuscitation guidelines recommend that chest compressions should be done over the lower half of the sternum, but evidence indicates that this is often associated with outflow obstruction. Emerging studies suggest that compression directly over the left ventricle (LV) may improve survival and outcomes, but rapid and reliable localization of the LV is a major obstacle for those first responding to OHCA. This study aimed to determine if a simplified, easy-to-use ultrasound device (bladder scanner) can reliably locate the heart when applied over the intercostal spaces of the anterior thorax in supine patients. Furthermore, we sought to describe the association between largest scan volumes and underlying cardiac anatomy with particular attention to the long axis of the LV. Methodology We recruited healthy male and female volunteers over 40 years of age. Using a bladder scanner to evaluate the left sternal border and mid-clavicular lines, we determined the maximal scan volumes at 10 intercostal spaces for each participant. Cardiac ultrasound was then used to evaluate the corresponding underlying cardiac anatomy and determine the area overlying the long-axis view of the LV. Descriptive statistics (means with standard deviations [SD], medians with interquartile ranges, and frequencies with proportions) were used to quantify demographic information, typical scan volumes across the chest, the frequencies of the best long-axis LV view location. This was then repeated for left sternal border assessments only. Kappa was determined when evaluating agreement between the largest left sternal border scan volume and the best long-axis LV view location. Results The long-axis LV was the predominant structure underlying the largest scan volume in 39/51 (76.5%) patients. When limited to left sternal border volumes only, the long axis of the LV was underlying the maximum volume intercostal space in 46/51 (90.2%; 95% confidence interval [CI]: 78.6%, 96.7%). The largest left sternal border scan volumes were located over the best long-axis LV view in 39/51 (76.5%, 95% CI: 62.5%, 87.2%) of the study participants with a Kappa statistic of 0.68 (95% CI: 0.52, 0.84; p < 0.0001).  Conclusions In this cross-sectional study of healthy volunteers, an easy-to-use ultrasound device (bladder scanner) was able to reliably localize the heart. Largest scan volumes over the left sternal border showed substantial agreement with the intercostal space overlying the long axis of the LV. Further investigations are warranted to determine if such localization is reliable in cardiac arrest patients.

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

BACKGROUND

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.

PURPOSE

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.

Optimum chest compression point might be located rightwards to the maximum diameter of the right ventricle: A preliminary, retrospective observational study

BACKGROUND

Some researchers have reported that applying compression closer to the maximum diameter of the left ventricle (Point_max.LV) is associated with worse clinical outcomes, challenging its traditional position as optimum compression point (Point_optimum). By locating the mid-sternum (the actual compression site) in terms of Point_max.LV and its right ventricular equivalent (Point_max.RV), we aimed to determine its optimum horizontal position associated with increased chances of return of spontaneous circulation (ROSC).

METHODS

A retrospective, cross-sectional study was performed at a university hospital from 2014 to 2019 on non-traumatic out-of-hospital cardiac arrest (OHCA) victims who underwent chest computed tomography. On absolute x-axis, we designated the x-coordinate of the mid-sternum (x_mid-sternum) as 0 and leftward direction as positive. Re-defining the x-coordinate of Point_max.RV and Point_max.LV as 0 and 1 interventricular unit (IVU), respectively, we could convert x_mid-sternum to "-x_max.RV/(x_max.LV - x_max.RV) (IVU)." Using multiple logistic regression analysis, we investigated whether this converted x_mid-sternum was associated with clinical outcomes, adjusting core elements of the Utstein template.

RESULTS

Among 887 non-traumatic OHCA victims, 124 [64.4 ± 16.7 years, 43 women (34.7%)] were enrolled. Of these, 80 (64.5%) exhibited ROSC. X_mid-sternum ranging from -1.71 to 0.58 (-0.36 ± 0.38) IVU was categorised into quintiles: <-0.60, -0.60 to -0.37, -0.37 to -0.22, -0.22 to -0.07 and ≥-0.07 (reference) IVU. The first quintile was positively associated with ROSC (odds ratio [95% confidence interval], 9.43 [1.44, 63.3]).

CONCLUSION

Point_optimum might be located far rightwards to Point_max.RV, challenging the traditional assumption identifying Point_optimum as Point_max.LV.

Cardiopulmonary resuscitation in pediatric pectus excavatum patients-Where is the heart?

BACKGROUND

In children with pectus excavatum, the posteriorly depressed sternum compresses and displaces the heart. However, the currently recommended compression site and depth for cardiopulmonary resuscitation have not been studied in this population.

AIM

This retrospective study investigated the location of the center of ventricles with the largest cross-sectional area to determine the optimal site and depth for chest compressions in pediatric pectus excavatum patients.

METHODS

Chest computed tomography images of 94 pediatric pectus excavatum patients before and after correction surgery were compared with normal patients. The caudal displacement of the ventricles was calculated by dividing the length of sternum by the length from the suprasternal notch to the transverse level of the largest cross-sectional area of the ventricles. The proportional leftward deviation of the center of the ventricles from the midline versus transverse diameter of the thorax was calculated. The remaining internal thickness was calculated at the midline assuming the recommended compression depth of one-third of the anterior to posterior diameter.

RESULTS

Compared with the normal population (mean = 81% [SD = 10.3%]), pediatric pectus excavatum patients showed caudal displacement of ventricles before (98.2% [15.1%], 95% CI of mean difference; 13.7%-20.5%, P < .001) and after correction (100.4% [13.5%], 95% CI of mean difference; 16.2%-22.5%, P < .001). Compared with the normal population (6.9% [2.7%]), pediatric pectus excavatum patients showed leftward deviation of ventricles before (16.2% [5.5%], 95% CI of mean difference; 8.2%-10.4%, P < .001) and after correction (13.3% [4.8%], 95% CI of mean difference; 5.3%-7.3%, P < .001). The remaining internal thickness assuming the recommended chest compression was <10 mm in 54/94(57.4%) and 18/94 (19.1%) of pediatric pectus excavatum patients before and after correction, respectively.

CONCLUSIONS

Pediatric pectus excavatum patients showed significant caudal displacement and leftward deviation of the ventricles compared with the normal population despite correction surgery and the currently recommended compression site and depth might injure intrathoracic structures without effective cardiac compression during cardiopulmonary resuscitation.

Bi-Level ventilation decreases pulmonary shunt and modulates neuroinflammation in a cardiopulmonary resuscitation model

Background

Optimal ventilation strategies during cardiopulmonary resuscitation are still heavily debated and poorly understood. So far, no convincing evidence could be presented in favour of outcome relevance and necessity of specific ventilation patterns. In recent years, alternative models to the guideline-based intermittent positive pressure ventilation (IPPV) have been proposed. In this randomized controlled trial, we evaluated a bi-level ventilation approach in a porcine model to assess possible physiological advantages for the pulmonary system as well as resulting changes in neuroinflammation compared to standard measures.

Methods

Sixteen male German landrace pigs were anesthetized and instrumented with arterial and venous catheters. Ventricular fibrillation was induced and the animals were left untreated and without ventilation for 4 minutes. After randomization, the animals were assigned to either the guideline-based group (IPPV, tidal volume 8–10 ml/kg, respiratory rate 10/min, F_iO₂1.0) or the bi-level group (inspiratory pressure levels 15–17 cmH₂O/5cmH₂O, respiratory rate 10/min, F_iO₂1.0). Mechanical chest compressions and interventional ventilation were initiated and after 5 minutes, blood samples, including ventilation/perfusion measurements via multiple inert gas elimination technique, were taken. After 8 minutes, advanced life support including adrenaline administration and defibrillations were started for up to 4 cycles. Animals achieving ROSC were monitored for 6 hours and lungs and brain tissue were harvested for further analyses.

Results

Five of the IPPV and four of the bi-level animals achieved ROSC. While there were no significant differences in gas exchange or hemodynamic values, bi-level treated animals showed less pulmonary shunt directly after ROSC and a tendency to lower inspiratory pressures during CPR. Additionally, cytokine expression of tumour necrosis factor alpha was significantly reduced in hippocampal tissue compared to IPPV animals.

Conclusion

Bi-level ventilation with a constant positive end expiratory pressure and pressure-controlled ventilation is not inferior in terms of oxygenation and decarboxylation when compared to guideline-based IPPV ventilation. Additionally, bi-level ventilation showed signs for a potentially ameliorated neurological outcome as well as less pulmonary shunt following experimental resuscitation. Given the restrictions of the animal model, these advantages should be further examined.

New physiological insights in ventilation during cardiopulmonary resuscitation

PURPOSE OF REVIEW

In the setting of cardiopulmonary resuscitation (CPR), classical physiological concept about ventilation become challenging. Ventilation may exert detrimental hemodynamic effects that must be balanced with its expected benefits. The risks of hyperventilation have been thoroughly addressed, even questioning the need for ventilation, emphasizing the need to prioritize chest compression quality. However, ventilation is mandatory for adequate gas exchange as soon as CPR is prolonged. Factors affecting the capability of chest compressions to produce alveolar ventilation are poorly understood. In this review, we discuss the conventional interpretation of interactions between ventilation and circulation, from the perspective of novel physiological observations.

RECENT FINDINGS

Many patients with cardiac arrest exhibit 'intrathoracic airway closure.' This phenomenon is associated with lung volume reduction, impedes chest compressions to generate ventilation and overall limits the delivered ventilation. This phenomenon can be reversed by the application of small levels of positive end-expiratory pressure. Also, a novel interpretation of the capnogram can rate the magnitude of this phenomenon, contributing to clarify the physiological meaning of exhaled CO2 and may help assess the real amount of delivered ventilation.

SUMMARY

Recent advances in the understanding of ventilatory physiology during CPR shows that capnogram analysis not only provides information on the quality of resuscitation but also on the amount of ventilation produced by chest compressions and on the total amount of ventilation.

Understanding the Adverse Hemodynamic Effects of Serious Thoracic Injuries During Cardiopulmonary Resuscitation: A Review and Approach Based on the Campbell Diagram

Chest compressions during cardiopulmonary resuscitation (CPR) generate cardiac output during cardiac arrest. Their quality performance is key to achieving the return of spontaneous circulation. Serious thoracic injuries (STIs) are common during CPR, and they can change the shape and mechanics of the thorax. Little is known about their hemodynamic effects, so a review of this emerging concept is necessary. The Campbell diagram (CD) is a theoretical framework that integrates the lung and chest wall pressure-volume curves, allowing us to assess the consequences of STIs on respiratory mechanics and hemodynamics. STIs produce a decrease in the compliance of the chest wall and lung. The representation of STIs on the CD shows a decrease in the intrathoracic negative pressure and a functional residual capacity decrease during the thoracic decompression, leading to a venous return impairment. The thorax with STIs is more vulnerable to the adverse hemodynamic effects of leaning, hyperventilation, and left ventricular outflow tract obstruction during CPR. A better understanding of the effects of STIs during CPR, and the study of avoidable injuries, can help to improve the effectiveness of chest compressions and the survival in cardiac arrest.

Combination of cardiac and thoracic pump theories in rodent cardiopulmonary resuscitation: a new method of three-side chest compression

BACKGROUND

High-quality cardiopulmonary resuscitation (HQ-CPR) is of paramount importance to improve neurological outcomes of cardiac arrest (CA). The purpose of this study was to evaluate chest compression methods by combining two theories: cardiac and thoracic pumps.

METHODS

Male Sprague-Dawley rats were used. Three types of chest compression methods were studied. The 1-side method was performed vertically with 2 fingers over the sternum. The 2-side method was performed horizontally with 2 fingers, bilaterally squeezing the chest wall. The 3-side method combined the 1-side and the 2-side methods. Rats underwent 10 min of asphyxial CA. We examined ROSC rates, the left ventricular functions, several arterial pressures, intrathoracic pressure, and brain tissue oxygen.

RESULTS

The 3-side group achieved 100% return of spontaneous circulation (ROSC) from asphyxial CA, while the 1-side group and 2-side group achieved 80% and 60% ROSC, respectively. Three-side chest compression significantly shortened the time for ROSC among the groups (1-side, 105 ± 36.0; 2-side, 141 ± 21.7; 3-side, 57.8 ± 12.3 s, respectively, P < 0.05). Three-side significantly increased the intrathoracic pressure (esophagus, 7.6 ± 1.9, 7.3 ± 2.8, vs. 12.7 ± 2.2; mmHg, P < 0.01), the cardiac stroke volume (the ratio of the baseline 1.2 ± 0.6, 1.3 ± 0.1, vs. 2.1 ± 0.6, P < 0.05), and the common carotid arterial pressure (subtracted by femoral arterial pressure 4.0 ± 2.5, 0.3 ± 1.6, vs. 8.4 ± 2.6; mmHg, P < 0.01). Three-side significantly increased the brain tissue oxygen (the ratio of baseline 1.4±0.1, 1.3±0.2, vs. 1.6 ± 0.04, P < 0.05).

CONCLUSIONS

These results suggest that increased intrathoracic pressure by 3-side CPR improves the cardiac output, which may in turn help brain oxygenation during CPR.

Kinetics of manual and automated mechanical chest compressions

AIM

Early onset of adequate chest compression is mandatory for cardiopulmonary resuscitation (CPR) following cardiac arrest. Transmission of forces from chest strain to the heart may be variable between manual and mechanical chest compressions. Furthermore, automated mechanical chest devices can deliver an active decompression, thus improving the venous return to the heart. This pilot study investigated the kinetics of cardiac deformation during these two CPR methods.

METHODS

Transesophageal echocardiographic analysis of the right ventricular wall behind the sternum during CPR was assessed during manual and mechanical chest compression in adult patients admitted to the emergency department for out-of-hospital cardiac arrest.

RESULTS

9 patients had manual and 11 mechanical chest compression. Mechanical chest compression was characterized by greater right ventricular lateral wall displacement [with a median (IQR) of 3.7 (3.12-4.27) vs. 2.53 (2.27-2.6) cm, p < 0.0001], and lower rising time [123 (102-169) vs. 187 (164-215) ms, p = 0.002], relaxing time [109 (102-127) vs. 211 (133-252) ms, p = 0.0003], compression rate [100.6 (99.6-102.2) vs. 131.9 (125.4-151.4) bpm, p < 0.0001], with compression-decompression time ratio of [1.04 (0.86-1.1) vs. 0.86 (0.78-0.96), p = 0.046].

CONCLUSION

Mechanical compared to manual chest compression delivered a more rapid compression and decompression of the cardiac structures at an adequate rate, with broader inward-outward movement of the ventricular walls suggesting greater emptying and filling of the ventricles. Transesophageal echocardiography may be a useful tool to assess the adequacy of chest compression without CPR interruption.

Duration of cardiac arrest requires different ventilation volumes during cardiopulmonary resuscitation in a pig model

There are few studies examining the ventilation strategies recommended by current CPR guidelines. We investigated the influence of different minute volume applying to untreated cardiac arrest with different duration, on resuscitation effects in a pig model. 32 Landrace pigs with 4 or 8 min (16 pigs each) ventricular fibrillation (VF) randomly received two ventilation strategies during CPR. "Guideline" groups received mechanical ventilation with a tidal volume of 7 ml/kg and a frequency of 10/min, while "Baseline" groups received a tidal volume (10 ml/kg) and a frequency used at baseline to maintain an end-tidal PCO₂ (P_ETCO₂) between 35 and 40 mmHg before VF. Mean airway pressures and intrathoracic pressures (P_IT) in the Baseline-4 min group were significantly higher than those in the Guideline-4 min group (all P < 0.05). Similar results were observed in the 8 min pigs, except for no significant difference in minimal P_IT and P_ETCO₂ during 10 min of CPR. Venous pH and venous oxygen saturation were significantly higher in the Baseline-8 min group compared to the Guideline-8 min group (all P < 0.05). Aortic pressure in the Baseline-8 min group was higher than in the Guideline-8 min group. Seven pigs in each subgroup of 4 min VF models achieved the return of spontaneous circulation (ROSC). Higher ROSC was observed in the Baseline-8 min group than in the Guideline-8 min group (87.5% vs. 37.5%, P = 0.039). For 4 min VF but not 8 min VF, a guideline-recommended ventilation strategy had satisfactory results during CPR. A higher minute ventilation resulted in better outcomes for subjects with 8 min of untreated VF through thoracic pump.

Association between left ventricular outflow tract opening and successful resuscitation after cardiac arrest

BACKGROUND

Survival after cardiac arrest depends on adequate cardiopulmonary resuscitation (CPR). Manual or mechanical external chest compression may be ineffective to restore circulation: structures subjected to external chest compression may differ in forces transfer to intrathoracic structures due to anatomic characteristics and physiological changes. This clinical study aims to assess the association of trans-oesophageal findings during CPR and successful resuscitation.

METHODS

Retrospective cohort study. Trans-oesophageal assessment of right ventricular fractional area change, right ventricular outflow tract fractional shortening, left ventricular volumes, ejection fraction, and aortic diameters were performed in refractory out-of-hospital cardiac arrest patients admitted to emergency department for extracorporeal CPR.

RESULTS

19 patients were analyzed. 15 of 19 patients (79%) received venous-arterial extracorporeal membrane oxygenation support. Resuscitation was successful with return of spontaneous circulation or electromechanical activity in 7 patients (group-SUXX) and failed in 12 patients (group-FAIL). 6 patients (32%) were alive at 24 h from the cardiac arrest, one patient (5%) survived to hospital discharge. Left ventricular outflow tract (LVOT) was open during CPR in all patients in group-SUXX and in 1 patient in group-FAIL (p 0.0002). None of the patients with closed LVOT had successful resuscitation. Patients in group-SUXX had a higher ejection fraction (p 0.03), ascending aortic diameter (p 0.04), and survival rate than those in group-FAIL (p 0.015). In a multiple variable Cox's proportional model LVOT opening was the only variable associated with successful resuscitation.

CONCLUSIONS

Trans-oesophageal echocardiography can be useful in the emergency setting of cardiopulmonary arrest for discriminating between successful and failing resuscitation.

The optimal chest compression point on sternum based on chest-computed tomography: A retrospective study

Background:

High-quality chest compression is crucial for cardiac arrest patients. However, only few studies are focusing on the optimal compression point.

Objective:

The aim of this study was to explore the optimal compression point based on chest-computed tomography.

Methods:

We retrospectively selected 166 adult health subjects between January 2018 and May 2018 in a university-affiliated hospital.

Results:

The median length of sternum was 14.9 cm. The median length from the inter-nipple line to the distal end of sternum was 1.0 cm. The median length from the point at which the maximal left ventricular diameter projected onto the sternum to the distal end of the sternum was −1.4 (–2.2 to 0.0) cm. The median value of the length from the inter-nipple line to the distal end of sternum plus the length from the point at which the maximal left ventricular diameter projected onto the sternum to the distal end of the sternum was 2.0 (1.0–3.1) cm.

Conclusion:

One size does not fit all. The point recommended by the current guideline may not appropriate for Chinese person. Further studies are required focusing on individual chest compression during cardiopulmonary resuscitation.

Ultra-low tidal volume ventilation-A novel and effective ventilation strategy during experimental cardiopulmonary resuscitation

BACKGROUND

The effects of different ventilation strategies during CPR on patient outcomes and lung physiology are still poorly understood. This study compares positive pressure ventilation (IPPV) to passive oxygenation (CPAP) and a novel ultra-low tidal volume ventilation (ULTVV) regimen in an experimental ventricular fibrillation animal model.

STUDY DESIGN

Prospective randomized controlled trial.

ANIMALS

30 male German landrace pigs (16-20 weeks).

METHODS

Ventricular fibrillation was induced in anesthetized and instrumented pigs and the animals were randomized into three groups. Mechanical CPR was initiated and ventilation was either provided by means of standard IPPV (RR: 10/min, Vt: 8-9 ml/kg, FiO2: 1,0, PEEP: 5 mbar), CPAP (O2-Flow: 10 l/min, PEEP: 5 mbar) or ULTVV (RR: 50/min, Vt: 2-3 ml/kg, FiO2: 1,0, PEEP: 5 mbar). Guideline-based advanced life support was applied for a maximum of 4 cycles and animals achieving ROSC were monitored for 6 h before terminating the experiment. Ventilation/perfusion ratios were performed via multiple inert gas elimination, blood gas analyses were taken hourly and extended cardiovascular measurements were collected constantly. Brain and lung tissue samples were taken and analysed for proinflammatory cytokine expression.

RESULTS

ULTVV provided sufficient oxygenation and ventilation during CPR while demanding significantly lower respiratory and intrathoracic pressures. V/Q mismatch was significantly decreased and lung injury was mitigated in surviving animals compared to IPPV and CPAP. Additionally, cerebral cytokine expression was dramatically reduced.

CONCLUSION

Ultra-low-volume ventilation during CPR in a porcine model is feasible and may provide lung-protective benefits as well as neurological outcome improvement due to lower inflammation. Our results warrant further studies and might eventually lead to new therapeutic options in the resuscitation setting.

Supportive technology in the resuscitation of out-of-hospital cardiac arrest patients

PURPOSE OF REVIEW

To discuss the increasing value of technological tools to assess and augment the quality of cardiopulmonary resuscitation (CPR) and, in turn, improve chances of surviving out-of-hospital cardiac arrest (OHCA).

RECENT FINDINGS

After decades of disappointing survival rates, various emergency medical services systems worldwide are now seeing a steady rise in OHCA survival rates guided by newly identified 'sweet spots' for chest compression rate and chest compression depth, aided by monitoring for unnecessary pauses in chest compressions as well as methods to better ensure full-chest recoil after compressions. Quality-assurance programs facilitated by new technologies that monitor chest compression rate, chest compression depth, and/or frequent pauses have been shown to improve the quality of CPR. Further aided by other technologies that enhance flow or better identify the best location for hand placement, the future outlook for better survival is even more promising, particularly with the potential use of another technology - extracorporeal membrane oxygenation for OHCA.

SUMMARY

After 5 decades of focus on manual chest compressions for CPR, new technologies for monitoring, guiding, and enhancing CPR performance may enhance outcomes from OHCA significantly in the coming years.

Does the British Heart Foundation PocketCPR training application improve confidence in bystanders performing CPR?

OBJECTIVES

Out-of-hospital cardiac arrest has poor prognosis and patients rarely survive unless they receive immediate cardiopulmonary resuscitation from bystanders. In 2012, the British Heart Foundation launched its PocketCPR training application to simplify bystander cardiopulmonary resuscitation training and overcome barriers to resuscitation. This study investigates whether the British Heart Foundation PocketCPR training application improves the confidence of bystanders who perform cardiopulmonary resuscitation during simulated resuscitation attempts.

METHODS

This is a mixed method study using a randomised crossover trial with questionnaire analysis. One hundred and twenty participants were randomised to either perform two minutes of cardiopulmonary resuscitation on a resuscitation manikin using the British Heart Foundation PocketCPR application or perform cardiopulmonary resuscitation without instruction. Participants completed a questionnaire to capture their confidence before completing the opposite arm of the study. Each participant then completed a second questionnaire to allow for comparison of levels of confidence.

RESULTS

Participants in this study were more confident in their overall performance of cardio-pulmonary resuscitation using the British Heart Foundation PocketCPR training application compared to performing cardiopulmonary resuscitation without instruction (mean confidence score (0-100): 50.41 with PocketCPR and 43.92 without (p = 0.026)). They were also more confident that the number of chest compressions in this study was correct (mean: 60.39 with PocketCPR vs. 46.10 without (p < 0.001)), and in the delivery of cardiopulmonary resuscitation without having recent cardiopulmonary resuscitation training (mean: 48.67 with PocketCPR vs. 39.79 without (p < 0.002)).

CONCLUSION

The British Heart Foundation PocketCPR training application improved the confidence of bystanders performing cardiopulmonary resuscitation during simulated resuscitation attempts.

Addition of Audiovisual Feedback During Standard Compressions Is Associated with Improved Ability

Introduction

A benefit of in-hospital cardiac arrest is the opportunity for rapid initiation of “high-quality” chest compressions as defined by current American Heart Association (AHA) adult guidelines as a depth 2–2.4 inches, full chest recoil, rate 100–120 per minute, and minimal interruptions with a chest compression fraction (CCF) ≥ 60%. The goal of this study was to assess the effect of audiovisual feedback on the ability to maintain high-quality chest compressions as per 2015 updated guidelines.

Methods

Ninety-eight participants were randomized into four groups. Participants were randomly assigned to perform chest compressions with or without use of audiovisual feedback (+/− AVF). Participants were further assigned to perform either standard compressions with a ventilation ratio of 30:2 to simulate cardiopulmonary resuscitation (CPR) without an advanced airway or continuous chest compressions to simulate CPR with an advanced airway. The primary outcome measured was ability to maintain high-quality chest compressions as defined by current 2015 AHA guidelines.

Results

Overall comparisons between continuous and standard chest compressions (n=98) were without significant differences in chest compression dynamics (p’s >0.05). Overall comparisons between +/− AVF (n = 98) were significant for differences in average rate of compressions per minute (p= 0.0241) and proportion of chest compressions within guideline rate recommendations (p = 0.0084). There was a significant difference in the proportion of high quality-chest compressions favoring AVF (p = 0.0399). Comparisons between chest compression strategy groups +/− AVF were significant for differences in compression dynamics favoring AVF (p’s < 0.05).

Conclusion

Overall, AVF is associated with greater ability to maintain high-quality chest compressions per most-recent AHA guidelines. Specifically, AVF was associated with a greater proportion of compressions within ideal rate with standard chest compressions while demonstrating a greater proportion of compressions with simultaneous ideal rate and depth with a continuous compression strategy.

Verification of the Optimal Chest Compression Depth for Children in the 2015 American Heart Association Guidelines: Computed Tomography Study

OBJECTIVE

The 2015 American Heart Association guidelines recommended pediatric rescue chest compressions of at least one-third the anteroposterior diameter of the chest, which equates to approximately 5 cm. This study evaluated the appropriateness of these two types by comparing their safeties in chest compression depth simulated by CT.

DESIGN

Retrospective study with data analysis conducted from January 2005 to June 2015 SETTING:: Regional emergency center in South Korea.

PATIENTS

Three hundred forty-nine pediatric patients 1-9 years old who had a chest CT scan.

INTERVENTIONS

Simulation of chest compression depths by CT.

MEASUREMENTS AND MAIN RESULTS

Internal and external anteroposterior diameter of the chest and residual internal anteroposterior diameter after simulation were measured from CT scans. The safe cutoff levels were differently applied according to age. One-third external anteroposterior diameters were compared with an upper limit of chest compression depth recommended for adults. Primary outcomes were the rates of overcompression to evaluate safety. Overcompression was defined as a negative value of residual internal anteroposterior diameter-age-specific cutoff level. Using a compression of 5-cm depth simulated by chest CT, 16% of all children (55/349) were affected by overcompression. Those 1-3 years old were affected more than those 4-9 years old (p < 0.001). Upon one-third compression of chest anteroposterior depth, only one subject (0.3%) was affected by overcompression. Rate of one-third external anteroposterior diameter greater than 6 cm in children 8 and 9 years old was 16.1% and 33.3%, respectively.

CONCLUSIONS

A chest compression depth of one-third anteroposterior might be more appropriate than the 5-cm depth chest compression for younger Korean children. But, one-third anteroposterior depth chest compression might induce deep compressions greater than an upper limit of compression depth for adults in older Korean children.

Improving CPR Performance

Cardiac arrest continues to represent a public health burden with most patients having dismal outcomes. CPR is a complex set of interventions requiring leadership, coordination, and best practices. Despite the widespread adoption of new evidence in various guidelines, the provision of CPR remains variable with poor adherence to published recommendations. Key steps health-care systems can take to enhance the quality of CPR and, potentially, to improve outcomes, include optimizing chest compressions, avoiding hyperventilation, encouraging intraosseous access, and monitoring capnography. Feedback devices provide instantaneous guidance to the rescuer, improve rescuer technique, and could impact patient outcomes. New technologies promise to improve the resuscitation process: mechanical devices standardize chest compressions, capnography guides resuscitation efforts and signals the return of spontaneous circulation, and intraosseous devices minimize interruptions to gain vascular access. This review aims at identifying a discreet group of interventions that health-care systems can use to raise their standard of cardiac resuscitation.

Consciousness induced during cardiopulmonary resuscitation: An observational study

BACKGROUND

Cardiopulmonary resuscitation-induced consciousness (CPRIC) is a phenomenon that has been described in only a handful of case reports. In this study, we aimed to describe CPRIC in out-of-hospital cardiac arrest (OHCA) patients and determine its association with survival outcomes.

METHODS

Retrospective study of registry-based data from Victoria, Australia between January 2008 and December 2014. Adult OHCA patients treated by emergency medical services (EMS) were included. Multivariable logistic regression was used to determine the association between CPRIC and survival to hospital discharge.

RESULTS

There were 112 (0.7%) cases of CPRIC among 16,558 EMS attempted resuscitations, increasing in frequency from 0.3% in 2008 to 0.9% in 2014 (p=0.004). Levels of consciousness consisted of spontaneous eye opening (20.5%), jaw tone (20.5%), speech (29.5%) and/or body movement (87.5%). CPRIC was independently associated with an increased odds of survival to hospital discharge in unwitnessed/bystander witnessed events (OR 2.09, 95% CI: 1.14, 3.81; p=0.02) but not in EMS witnessed events (OR 0.98, 95% CI: 0.49, 1.96; p=0.96). Forty-two (37.5%) patients with CPRIC received treatment with one or more of midazolam (35.7%), opiates (5.4%) or muscle relaxants (3.6%). When stratified by use of these medications, CPRIC in unwitnessed/bystander witnessed patients was associated with improved odds of survival to hospital discharge if medications were not given (OR 3.92, 95% CI: 1.66, 9.28; p=0.002), but did not influence survival if these medications were given (OR 0.97, 95% CI: 0.37, 2.57; p=0.97).

CONCLUSION

Although CPRIC is uncommon, its occurrence is increasing and may be associated with improved outcomes. The appropriate management of CPRIC requires further evaluation.