Explorative study on lower inflection point dynamics during cardiopulmonary resuscitation: Potential implications for airway management

INTRODUCTION

In patients undergoing cardiopulmonary resuscitation (CPR) after an Out-of-Hospital Cardiac Arrest (OHCA), intrathoracic airway closure can impede ventilation, adversely affecting patient outcomes. This explorative study investigates the evolution of intrathoracic airway closure by analyzing the lower inflection point (LIP) during the inspiration phase of CPR, aiming to identify the potential thresholds for alveolar recruitment.

METHODS AND MATERIALS

Eleven OHCA patients undergoing CPR with endotracheal intubation and manual bag ventilation were included. Flow and pressure measurements were obtained using Sensirion SFM3200AW and Wika CPT2500 sensors attached to the endotracheal tube, connected to a Surface Go Tablet for data collection. Flow data was analyzed in Microsoft Excel, while pressure data was processed using the Wika USBsoft2500 application. Analysis focused on the inspiration phase of the first 6-8 breaths, with an additional 2 breaths recorded and analyzed at the end of CPR.

RESULTS

Across the cohort, the median tidal volume was 870.00 milliliter (mL), average flow was 31.90 standard liters per minute (slm), and average pressure was 17.21 cmH2O. The calculated average LIP was 31.47 cmH2O. Most cases (72.7%) exhibited a negative trajectory in LIP evolution during CPR, with 2 cases (18.2%) showing a positive trajectory and 1 case remaining inconclusive. The average LIP in the first 8 breaths was significantly higher than in the last 2 breaths (p = 0.018). No significant correlation was found between average LIP and return of spontaneous circulation (ROSC), compression depth, frequency, or end-tidal CO2 (EtCO2). However, a significant negative correlation was observed between the average LIP of the last 2 breaths and CPR duration (p = 0.023).

VALIDATION

LIP calculation in low-flow ventilations using the novel mathematical method yielded values consistent with those reported in the literature.

DISCUSSION/CONCLUSION

These explorative data demonstrate a predominantly negative trajectory in LIP evolution during CPR, suggesting potential challenges in maintaining airway patency. Limitations include a small sample size and sensor recording issues. Further research is warranted to explore the evolution of LIP and its implications for personalized ventilation strategies in CPR.

Development of Prediction Models for Cardiac Compression in Pectus Excavatum Based on Three-Dimensional Surface Images

In pectus excavatum, three-dimensional (3D) surface imaging provides an accurate and radiation-free alternative to computed tomography (CT) to determine severity. Yet, it does not allow for cardiac evaluation since 3D imaging solely captures the chest wall surface. The objective was to develop a 3D image-based prediction model for cardiac compression in patients evaluated for pectus excavatum. A prospective cohort study was conducted including consecutive patients referred for pectus excavatum who received a thoracic CT. Additionally, 3D images were acquired. The external pectus depth, its length, craniocaudal position, cranial slope, asymmetry, anteroposterior distance and chest width were calculated from 3D images. Together with baseline patient characteristics they were submitted to forward multivariable logistic regression to identify predictors for cardiac compression. Cardiac compression on CT was used as reference. The model's performance was depicted by the area under the receiver operating characteristic (AUROC) curve. Internal validation was performed using bootstrapping. Sixty-one patients were included of whom 41 had cardiac compression on CT. A combination of the 3D image derived external pectus depth and external anteroposterior distance was identified as predictive for cardiac compression, yielding an AUROC of 0.935 (95% confidence interval [CI]: 0.878-0.992) with an optimism of 0.006. In a second model for males alone, solely the external pectus depth was identified as predictor, yielding an AUROC of 0.947 (95% CI: 0.892-1.000) with an optimism of 0.0002. We have developed two 3D image-based prediction models for cardiac compression in patients evaluated for pectus excavatum which provide an outstanding discriminatory performance between the presence and absence of cardiac compression with negligible optimism.

Thoracoabdominal aneurysm causing functional mitral valve stenosis after total arch replacement

Large thoracic and thoraco-abdominal aneurysms may compress adjacent mediastinal structures. We present a case of a large thoraco-abdominal aneurysm compressing the left atrium and leading to functional mitral valve stenosis after total aortic arch repair, requiring urgent open thoraco-abdominal aneurysm repair.

The effect of personal protective equipment on cardiac compression quality

Introduction

Cardiac compression is a cumbersome procedure. The American Heart Association suggests switching of cardiopulmonary resuscitation (CPR) provider every 2 min to prevent any decrease in resuscitation quality. High quality CPR is associated with improved outcomes. Previous studies have highlighted the difficulties in providing high quality CPR particularly while wearing personal protective equipment (PPE). This study aimed to evaluate the impact of personal protective equipment (PPE) use on CPR quality in prehospital cardiac arrest situations.

Methods

In this prospective simulation study, we compared the cardiac compression qualities and fatigue rates among prehospital health care professionals (HCPs) who were or were not using PPE.

Results

A total of 76 prehospital HCPs comprising 38 compression teams participated in this study. The mean compression rate was 117.71 ± 8.27/min without PPE and 115.58 ± 9.02/min with PPE (p = 0.191). Overall compression score was 86.95 ± 4.39 without PPE and 61.89 ± 14.43 with PPE (p < 0.001). Post-cardiac compression fatigue score was 4.42 ± 0.5 among HCPs who used their standard uniform and 7.74 ± 0.92 among those who used PPE (p < 0.001). The overall compression score difference between the two conditions was 25.05 ± 11.74 and the fatigue score difference was 3.31 ± 0.98.

Discussion

PPE use is associated with decreased cardiac compression quality and significantly higher fatigue rates than those associated with the use of standard uniforms. Routine use of mechanical compression devices should be considered when PPE is required for out-of-cardiac arrests.

Case report: ventricular fibrillation and cardiac arrest provoked by forward bending in adolescent with severe pectus excavatum

Background

Life-threatening arrhythmias have been reported in patients with severe pectus excavatum in absence of other cardiac abnormalities. Literature is scarce regarding diagnosis, cause and management of this problem, particularly regarding the question as to whether the placement of an implantable cardioverter-defibrillator (ICD) is necessary.

Case summary

A 19-year-old male patient with severe pectus excavatum was scheduled for elective surgical correction. During forward bending for epidural catheter placement, syncope and ventricular fibrillation (VF) occurred resulting in cardiac arrest. After successful cardiopulmonary resuscitation, extensive analysis was performed and showed no cause for VF other than cardiac compression (particularly of the left atrium, right atrium, and ventricle to a lesser degree) due to severe pectus excavatum. Postponed correction by modified Ravitch was performed without ICD placement, with an uneventful post-operative recovery. Eighteen months after surgery, the patient remains well. Upon specific request, he did remember dizzy spells when tying shoelaces. He always considered this unremarkable.

Discussion

In severe pectus excavatum with cardiac compression, forward bending can decrease central venous return and cardiac output, causing hypotension, arrhythmia, and cardiac arrest. In absence of structural or electric abnormalities, cardiac compression by severe pectus excavatum was considered a reversible cause of VF and ICD placement unnecessary. Patients with cardiac compression due to severe pectus excavatum may report pre-existing postural symptoms upon specific request. When these postural symptoms are present, extreme and prolonged forward bending postures should be avoided.

Rib osteochondroma causing cardiac compression in a pediatric patient

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Osteochondromas are considered the most common benign tumors of bony origin.

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Exostosis are slow growing masses usually diagnosed before the third decade of life.

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A computed tomography scan offers a more accurate tool in the diagnosis of this type of condition.

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Rib exostosis occurs more frequently in males than females with a ratio of 1.5:1.

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Costal osteochondromas mostly occur as a part of hereditary multiple osteochondromas.

Introduction and importance

Rib osteochondromas are rare genetic disorders, which can present as bony exostosis causing compression, impingement and damage to surrounding vessels, organs and structures within the thoracic cavity. The objective of this study was to clearly describe a rare presentation of rib osteochondromas in a pediatric patient along with managing techniques.

Case

A 9-year-old girl was admitted to the hospital due to shortness of breath on exertion. Physical examination did not reveal any abnormalities except for small bony projections over the left 5th rib. Computed tomography (CT) scan showed a bony lesion on the left fifth rib causing cardiac compression. Video-assisted thoracoscopy (VAT) was done, which showed a bony exostosis compressing the left ventricle, the lesion was resected without any complications. Final pathology confirmed the diagnosis of osteochondroma measuring 2.0 cm × 2.0 cm × 1.5 cm, along with a thickness of 0.4 cm. Post-operative recovery was well, with no morbidities and the patient was discharged without any complications. On the post-operative follow up, the patient showed significant improvement in her symptoms.

Clinical discussion

Our reported case is a rare example of a solitary costal osteochondroma leading to serious complications because of its shape, size, and location. Previous reports have not addressed any significant traumatic event or impact prior to the occurrence of symptoms related to the cases, including the case of our patient. Cases of rib exostosis were surgically approached using different techniques most often through thoracotomy.

Conclusions

Rib osteochondromas are rare benign bony lesions which can cause cardiac symptoms secondary to direct compression. They can be resected safely via video assisted thoracoscopy (VAT) or limited thoracotomy.

[A rare cause of type 2 non-ST-elevation myocardial infarction: Cardiac compression and left ventricular obstruction by a giant hiatal hernia]

We report the case of a 89 year-old woman admitted to the emergency department for epigastric pain, nausea, vomiting. Because of a circulatory failure with electrocardiographic ST changes and a slight elevation of ultra-sensible troponin, a coronary angiography was performed and found normal coronary arteries. Thoraco-abdominal CT scan revealed a large hiatal hernia causing a cardiac compression, and a left intraventricular obstruction showed by Doppler echocardiography. All signs resolved after fasting and gastric drainage.

A case report of a giant hiatal hernia mimicking an ST-elevation myocardial infarction

Background

Acute coronary syndrome (ACS) can be a life-threatening condition. However, identification of patients with ACS can be challenging, especially among women, and clinical presentation can often overlap with other medical entities.

Case summary

A 61-year-old woman with a history of stable bronchial asthma presented with worsening dyspnoea for spiroergometry. During bicycle exercise testing, she developed acute chest pain and her electrocardiogram showed significant ST-segment elevations. High-sensitivity cardiac troponin was elevated and a coronary angiography was performed showing normal coronary arteries. Cardiac magnetic resonance imaging showed no signs of myocardial infarction, myocarditis or Takotsubo cardiomyopathy but the incidental finding of a giant hiatal hernia impeding the filling of the left atrium. The giant hernia was surgically corrected, and the patient’s exertional dyspnoea fully relieved during follow-up.

Discussion

Hiatal hernia might compress cardiac structures, cause exertional dyspnoea and mimic ST-elevation myocardial infarction.

Effect of knee positions on cardiac compression variables in cardiopulmonary resuscitation of rescuer; Manikin study

The aim of the study was to analyze the effect of knee positions on cardiac compression variables in cardiopulmonary resuscitation (CPR) using the manikin. Adult with career of CPR instructor (n=9; mean age, 27.11±6.60 years; mean heights, 177.39±4.40 cm; mean weights, 69.45±14.85 kg) participated in the experiment, and each participant performed cardiac compression from two different knee positions. Cardiac compression was 30 times per minute for each position with order of position randomized. The results obtained from variables of cardiac compression force were composed of compression velocity, elapsed time, decay rate, and loading rate in maximum and minimum medial-lateral, anterior-posterior (AP), vertical direction respectively. The above variables in 20.3 cm of knee position showed effective result than that of 50 cm of knee position, while maximum AP compression force increased. Given the often predictable setting of sports and exercise rehabilitation related with cardiac arrest, CPR relative to change of knee position were significantly associated with more efficient cardiac compression variables. These data have significant implications for health services program in fields of sports and exercise rehabilitation.

Cardiac Tamponade

Cardiac tamponade is caused by an abnormal increase in fluid accumulation in the pericardial sac, which, by raising intracardiac pressures, impedes normal cardiac filling and reduces cardiac output, sometimes dramatically so. This article outlines the pathophysiology, clinical features, and treatment of this important clinical condition highlighting the important role played by echocardiography in diagnosis and management.

The mechanism of blood flow during chest compressions for cardiac arrest is probably influenced by the patient's chest configuration

Aim

Mechanical assist devices are sometimes needed during resuscitation efforts of patients with prolonged cardiac arrest. Two such devices, the AutoPulse and the LUCAS, have different mechanisms of action. We propose that the effectiveness of mechanical assist devices is somewhat dependent on the configuration and compliance of the patient's chest wall.

Methods

A previous study of patients with out‐of‐hospital cardiac arrest in Arizona reported that survivors were younger and many were observed to have narrow anterior–posterior chest diameters. These observations suggest that the predominant mechanism of blood flow during cardiopulmonary resuscitation of individuals with primary cardiac arrest is influenced by the patient's anterior–posterior chest diameter and compliance. It is proposed that in older individuals with an increased anterior–posterior chest diameter and decreased chest compliance that the AutoPulse, which works by increasing intrathoracic pressures, may be more effective. In contrast, the LUCAS device, which works predominately by compression of the sternum, is probably more effective in patients with narrower anterior–posterior diameters and a more compliant chest.

Results

These hypotheses need to be confirmed by researchers who not only have access to the lateral chest roentgenograms of patients with cardiac arrest, to determine their anterior–posterior chest diameter, but also to the type of mechanical device that was used during resuscitation efforts and their patient's survival. If the observations herein proposed are confirmed, hospitals and paramedics may ideally need to have one of each type of mechanical chest compression unit and select the one to use depending on the patient's age and anterior–posterior chest diameter.

Conclusions

The mechanism of blood flow in patients with cardiac arrest is predominantly secondary to cardiac compression in younger patients with narrow anterior chest diameters and predominately secondary to the thoracic pump mechanism in older patients with emphysema.