Impact of lung structure on airway opening index during mechanical versus manual chest compressions in a porcine model of cardiac arrest

Background: Current guidelines recommend that chest compressions for children be done at either 1.5 inches depth and 100 per minute, or one-third the chest A-P diameter depth and 100 per minute. Neither of these recommendations is based on scientific evidence. Objective: As part of an ongoing efficacy trial, we sought to compare the safety of three different chest compression strategies in a porcine model of pediatric cardiac arrest. Methods: Following anesthesia, instrumentation, and induction of asphyxial cardiac arrest, we randomly assigned 48 domestic swine to one of three groups (n=16 per group). The mean mass of 25.7 kg approximates the 50 th percentile for a 7 year old. Group 1 had fixed chest compression depth of 1.5 inches/rate 100; group 2 had fixed proportional depth of one-third the A-P diameter/rate 100; group 3 used an adaptive algorithm that incrementally increased chest compression rate and/or depth from baseline 1.5in (max: 2.13in) and 100/min (max; 130/min) every 25s while coronary perfusion pressure was below 25mmHg. Necropsies were independently performed by a veterinarian and veterinary technologist who were blinded to group assignment. The primary safety outcome was unrecoverable injury (i.e. toxicity), which we defined as either a total lung injury score ≥16 (score can range from 0 to 20) plus presence of hemothorax, or disruption of either the aorta or vena cava. Data were analyzed with the Bayesian Beta Binomial to determine if within-group toxicity exceeded an unacceptable level (30%) with a pre-selected posterior predictive threshold of 0.75(ptox). Lung injury scores between groups were compared with Kruskal-Wallis tests. Results: Median total lung injury scores were: 12 for group 1; 18 for group 2; 14 for group 3. Group 2 was significantly different from both groups 1 and 3 (p<0.001). Groups 1 and 3 did not differ (p=0.24). Toxicity occurred in zero animals in group 1 (ptox=0.0001); 7 animals in group 2 (ptox=0.8180); and 1 animal in group 3 (ptox=0.0076). The posterior probability threshold was exceeded in group 2 which warranted termination of the treatment arm for safety. Conclusions: Chest compressions performed at a depth of one-third the A-P diameter are unsafe. The safety of this approach in children should be carefully evaluated.

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Abstract 13027: Investigating the Airway Opening Index During Cardiopulmonary Resuscitation

Circulation ◽

10.1161/circ.144.suppl_2.13027 ◽

2021 ◽

Vol 144 (Suppl_2) ◽

Author(s):

Shiv Bhandari ◽

Jason Coult ◽

Natalie Bulger ◽

Catherine Counts ◽

Heemun Kwok ◽

...

Keyword(s):

Cardiac Arrest ◽

Retrospective Study ◽

Cardiopulmonary Resuscitation ◽

Statistical Significance ◽

Chest Compressions ◽

Airway Patency ◽

Significant Difference ◽

Airway Opening ◽

Automated Methods ◽

Hospital Cardiac Arrest

Introduction: In 40-70% of out-of-hospital cardiac arrest (OHCA) cases, chest compressions (CCs) during CPR induce measurable oscillations in capnography (E T CO 2 ). Recent studies suggest the magnitude and frequency of oscillations are due to intrathoracic airflow dependent on airway patency. These oscillations can be quantified by the Airway Opening Index (AOI), ranging from 0-100%. We sought to develop, automate, and evaluate multiple methods of computing AOI throughout CPR. Methods: We conducted a retrospective study of all OHCA cases in Seattle, WA during 2019. E T CO 2 and impedance waveforms from LifePak 15 defibrillators were annotated for the presence of intubation and CPR, and imported into MATLAB for analysis. Four proposed methods for computing AOI were developed (Fig. 1) using peak E T CO 2 in conjunction with ΔE T CO 2 (oscillations in E T CO 2 from CCs). We examined the feasibility of automating ΔE T CO 2 and AOI calculation during CCs throughout OHCA resuscitation and evaluated differences in mean AOI using each method. Statistical significance was assessed with ANOVA (alpha = 0.05). Results: AOI was measurable in 312 of 465 cases. Mean [95% confidence interval] AOI across all cases was 34.3% [32.0-36.5%] for method 1, 27.6% [25.5-29.7%] for method 2, 22.7% [21.1-24.3%] for method 3, and 28.8% [26.6-31.0%] for method 4. Mean AOI was significantly different across the four methods (p<0.001), with the greatest difference between method 1 and 3 (11.6%, p<0.001), but no significant difference between methods 2 and 4 (p=0.44). Mean ΔE T CO 2 was 7.76 [7.08-8.44] mmHg. Conclusion: We implemented four proposed methods of automatically calculating AOI during OHCA. Each method produced a different average AOI. Consistent, automated methods to measure AOI provide the foundation to evaluate if, and how, AOI may change with treatment or predict outcomes. These four approaches require additional investigation to understand which may be best suited to improve OHCA care.

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Evaluation of coronary blood flow velocity during cardiac arrest with circulation maintained through mechanical chest compressions in a porcine model

BMC Cardiovascular Disorders ◽

10.1186/1471-2261-11-73 ◽

2011 ◽

Vol 11 (1) ◽

Cited By ~ 5

Author(s):

Henrik Wagner ◽

Bjarne Madsen Hardig ◽

Stig Steen ◽

Trygve Sjoberg ◽

Jan Harnek ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Arrest ◽

Flow Velocity ◽

Coronary Blood Flow ◽

Blood Flow Velocity ◽

Porcine Model ◽

Chest Compressions ◽

Coronary Blood Flow Velocity

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Even Four Minutes of Poor Quality of CPR Compromises Outcome in a Porcine Model of Prolonged Cardiac Arrest

BioMed Research International ◽

10.1155/2013/171862 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 12

Author(s):

Heng Li ◽

Lei Zhang ◽

Zhengfei Yang ◽

Zitong Huang ◽

Bihua Chen ◽

...

Keyword(s):

Cardiac Arrest ◽

Porcine Model ◽

Coronary Perfusion Pressure ◽

Poor Quality ◽

Spontaneous Circulation ◽

Coronary Perfusion ◽

Chest Compressions ◽

Yorkshire Pigs ◽

Anterior Posterior

Objective. Untrained bystanders usually delivered suboptimal chest compression to victims who suffered from cardiac arrest in out-of-hospital settings. We therefore investigated the hemodynamics and resuscitation outcome of initial suboptimal quality of chest compressions compared to the optimal ones in a porcine model of cardiac arrest.Methods. Fourteen Yorkshire pigs weighted 30 ± 2 kg were randomized into good and poor cardiopulmonary resuscitation (CPR) groups. Ventricular fibrillation was electrically induced and untreated for 6 mins. In good CPR group, animals received high quality manual chest compressions according to the Guidelines (25% of animal’s anterior-posterior thoracic diameter) during first two minutes of CPR compared with poor (70% of the optimal depth) compressions. After that, a 120-J biphasic shock was delivered. If the animal did not acquire return of spontaneous circulation, another 2 mins of CPR and shock followed. Four minutes later, both groups received optimal CPR until total 10 mins of CPR has been finished.Results. All seven animals in good CPR group were resuscitated compared with only two in poor CPR group (P<0.05). The delayed optimal compressions which followed 4 mins of suboptimal compressions failed to increase the lower coronary perfusion pressure of five non-survival animals in poor CPR group.Conclusions. In a porcine model of prolonged cardiac arrest, even four minutes of initial poor quality of CPR compromises the hemodynamics and survival outcome.

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Abstract 254: Synchronized Chest Compressions for Pseudo-PEA: Proof of Concept and Synching Algorithm

Circulation ◽

10.1161/circ.140.suppl_2.254 ◽

2019 ◽

Vol 140 (Suppl_2) ◽

Author(s):

Keith Marill ◽

James J Menegazzi ◽

Allison C Koller ◽

Matthew Sundermann ◽

David D Salcido

Keyword(s):

Cardiac Arrest ◽

Chest Compression ◽

Porcine Model ◽

Pulseless Electrical Activity ◽

Compression Therapy ◽

Coronary Perfusion Pressure ◽

Coronary Perfusion ◽

Compression Rate ◽

Proof Of Concept ◽

Chest Compressions

Introduction: Pulseless electrical activity (PEA) is a common rhythm in cardiac arrest with a persistently poor outcome. This report describes our successful development of a synchronized compression device and algorithm to treat PEA with or without intrinsic myocardial contractions. Methods: We adapted our previously developed signal-guided CPR system to provide synchronized compressions in a porcine model of cardiac arrest. We describe the first comparison of unsynchronized to synchronized compressions in a single animal as a proof-of-concept. We developed an algorithm to provide optimal synchronized chest compressions regardless of intrinsic heartrate while simultaneously maintaining the chest compression rate within a desired range. We tested the algorithm with computer simulations measuring the proportion of intrinsic and compression beats that were synchronized, and the compression rate and its standard deviation, as a function of intrinsic heartrate and heartrate jitter. Results: We demonstrate and compare unsynchronized versus synchronized chest compressions in a single porcine model with an intrinsic rhythm and hypotension. Synchronized, but not unsynchronized, chest compressions were associated with increased blood pressure and coronary perfusion pressure (Figure). Our synchronized chest compression algorithm is able to provide synchronized chest compressions to over 90% of intrinsic beats for most heartrates while maintaining an average compression rate between 95 and 135 BPM with relatively low variability. Conclusion: Synchronized chest compression therapy for pulseless electrical rhythms is feasible. A high degree of synchronization can be maintained over a broad range of intrinsic heart rates while maintaining the compression rate within a satisfactory range. Further investigation to assess benefit for treatment of PEA is warranted.

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