Chest wall mechanics during mechanical chest compression and its relationship to CPR-related injuries and survival

British societies guideline on the management of emergencies in implantable left ventricular assist device recipients in transplant centres

An implantable left ventricular assist device (LVAD) is indicated as a bridge to transplantation or recovery in the United Kingdom (UK). The mechanism of action of the LVAD results in a unique state of haemodynamic stability with diminished arterial pulsatility. The clinical assessment of an LVAD recipient can be challenging because non-invasive blood pressure, pulse and oxygen saturation measurements may be hard to obtain. As a result of this unusual situation and complex interplay between the device and the native circulation, resuscitation of LVAD recipients requires bespoke guidelines. Through collaboration with key UK stakeholders, we assessed the current evidence base and developed guidelines for the recognition of clinical deterioration, inadequate circulation and time-critical interventions. Such guidelines, intended for use in transplant centres, are designed to be deployed by those providing immediate care of LVAD patients under conditions of precipitous clinical deterioration. In summary, the Joint British Societies and Transplant Centres LVAD Working Group present the UK guideline on management of emergencies in implantable LVAD recipients for use in advanced heart failure centres. These recommendations have been made with a UK resuscitation focus but are widely applicable to professionals regularly managing patients with implantable LVADs.

Study of risk factors for injuries due to cardiopulmonary resuscitation with special focus on the role of the heart: A machine learning analysis of a prospective registry with multiple sources of information (ReCaPTa Study)

Background

The study of thoracic injuries and biomechanics during CPR requires detailed studies that are very scarce. The role of the heart in CPR biomechanics has not been determined. This study aimed to determine the risk factors importance for serious ribcage damage due to CPR.

Methods

Data were collected from a prospective registry of out-of-hospital cardiac arrest between April 2014 and April 2017. This study included consecutive out-of-hospital CPR attempts undergoing an autopsy study focused on CPR injuries. Cardiac mass ratio was defined as the ratio of real to expected heart mass. Pearson's correlation coefficient was used to select clinically relevant variables and subsequently classification tree models were built. The Gini index was used to determine the importance of the associated serious ribcage damage factors. The LUCAS® chest compressions device forces and the cardiac mass were analyzed by linear regression.

Results

Two hundred CPR attempts were included (133 manual CPR and 67 mechanical CPR). The mean age of the sample was 60.4 ± 13.5, and 56 (28%) were women. In all, 65.0% of the patients presented serious ribcage damage. From the classification tree build with the clinically relevant variables, age (0.44), cardiac mass ratio (0.26), CPR time (0.22), and mechanical CPR (0.07), in that order, were the most influential factors on serious ribcage damage. The chest compression forces were greater in subjects with higher cardiac mass.

Conclusions

The heart plays a key role in CPR biomechanics being cardiac mass ratio the second most important risk factor for CPR injuries.

Rib fractures and other injuries after cardiopulmonary resuscitation for non-traumatic cardiac arrest: a systematic review and meta-analysis

PURPOSE

This study aims to ascertain the prevalence of rib fractures and other injuries resulting from CPR and to compare manual with mechanically assisted CPR. An additional aim was to summarize the literature on surgical treatment for rib fractures following CPR.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Embase, Medline Ovid, Cochrane Central, Web of Science, and Google Scholar.

REVIEW METHODS

The databases were searched to identify studies reporting on CPR-related injuries in patients who underwent chest compressions for a non-traumatic cardiopulmonary arrest. Subgroup analysis was conducted to compare the prevalence of CPR-related injuries in manual versus mechanically assisted chest compressions. Studies reporting on surgery for CPR-related rib fractures were also reviewed and summarized.

RESULTS

Seventy-four studies reporting CPR-related injuries were included encompassing a total of 16,629 patients. Any CPR-related injury was documented in 60% (95% confidence interval [95% CI] 49-71) patients. Rib fractures emerged as the most common injury, with a pooled prevalence of 55% (95% CI 48-62). Mechanically assisted CPR, when compared to manual CPR, was associated with a higher risk ratio for CPR-related injuries of 1.36 (95% CI 1.17-1.59). Eight studies provided information on surgical stabilization of CPR-related rib fractures. The primary indication for surgery was the inability to wean from mechanical ventilation in the presence of multiple rib fractures.

CONCLUSION

Rib fractures and other injuries frequently occur in patients who undergo CPR after a non-traumatic cardiopulmonary arrest, especially when mechanical CPR is administered. Surgical stabilization of CPR-related rib fractures remains relatively uncommon.

LEVEL OF EVIDENCE

Level III, systematic review and meta-analysis.

Characterization of mechanical properties of adult chests during pre-hospital manual chest compressions through a simple viscoelastic model

AIM

The purpose of this study was to develop a simple viscoelastic model to characterize the mechanical properties of chests during manual chest compressions in pre-hospital cardiopulmonary resuscitation (CPR).

METHODS

Force and acceleration signals were extracted from CPR monitors used during pre-hospital resuscitation attempts on adult patients. Individual chest compressions were identified and segmented from the chest displacement computed using the force and acceleration. Each compression-recoil cycle was characterized by its elastic coefficient k (a measure of stiffness) and its compression and recoil damping coefficients, dc and dr, respectively (measures of viscosity). We compared the estimated and the calculated chest displacement to assess the goodness of fit of the model. We characterized the chest of patients at the beginning of CPR in relation to sex and age, and their variation as CPR progressed.

RESULTS

A total of 1,156,608 chest compressions from 615 patients were analysed. Mean (95% CI) coefficient of determination R2 for the viscoelastic model was 97.9% (97.8-98.1). At the beginning of CPR, k was 104.9 N⋅cm-1 (102.0-107.8), dc was 2.868 N⋅s⋅cm-1 (2.751-2.984) and dr was 4.889 N⋅s⋅cm-1 (4.648-5.129). Damping during recoil was significantly higher than during compression. Stiffness was lower in women than in men. There were no differences in damping coefficients with sex but a higher dr with increasing age. All model coefficients decreased with compression count, with an overall decrease after 3,000 chest compressions of 34.6%, 48.8% and 37.2%, respectively.

CONCLUSION

The model accurately described adult chest mechanical properties during CPR, highlighting differences between compression and recoil, sex and age, and a progressive reduction in chest stiffness and viscosity along resuscitation. Our findings may merit further investigation into whether patient-tailored and time-sensitive chest compression technique may be appropriate.

Do cardiopulmonary resuscitation real-time audiovisual feedback devices improve patient outcomes? A systematic review and meta-analysis

BACKGROUND

Cardiac arrest is a leading cause of mortality in America and has increased in the incidence of cases over the last several years. Cardiopulmonary resuscitation (CPR) increases survival outcomes in cases of cardiac arrest; however, healthcare workers often do not perform CPR within recommended guidelines. Real-time audiovisual feedback (RTAVF) devices improve the quality of CPR performed. This systematic review and meta-analysis aims to compare the effect of RTAVF-assisted CPR with conventional CPR and to evaluate whether the use of these devices improved outcomes in both in-hospital cardiac arrest (IHCA) and out-of-hospital cardiac arrest (OHCA) patients.

AIM

To identify the effect of RTAVF-assisted CPR on patient outcomes and CPR quality with in- and OHCA.

METHODS

We searched PubMed, SCOPUS, the Cochrane Library, and EMBASE from inception to July 27, 2020, for studies comparing patient outcomes and/or CPR quality metrics between RTAVF-assisted CPR and conventional CPR in cases of IHCA or OHCA. The primary outcomes of interest were return of spontaneous circulation (ROSC) and survival to hospital discharge (SHD), with secondary outcomes of chest compression rate and chest compression depth. The methodological quality of the included studies was assessed using the Newcastle-Ottawa scale and Cochrane Collaboration's "risk of bias" tool. Data was analyzed using R statistical software 4.2.0. results were statistically significant if P < 0.05.

RESULTS

Thirteen studies (n = 17600) were included. Patients were on average 69 ± 17.5 years old, with 7022 (39.8%) female patients. Overall pooled ROSC in patients in this study was 37% (95% confidence interval = 23%-54%). RTAVF-assisted CPR significantly improved ROSC, both overall [risk ratio (RR) 1.17 (1.001-1.362); P = 0.048] and in cases of IHCA [RR 1.36 (1.06-1.80); P = 0.002]. There was no significant improvement in ROSC for OHCA (RR 1.04; 0.91-1.19; P = 0.47). No significant effect was seen in SHD [RR 1.04 (0.91-1.19); P = 0.47] or chest compression rate [standardized mean difference (SMD) -2.1; (-4.6-0.5)]; P = 0.09]. A significant improvement was seen in chest compression depth [SMD 1.6; (0.02-3.1); P = 0.047].

CONCLUSION

RTAVF-assisted CPR increases ROSC in cases of IHCA and chest compression depth but has no significant effect on ROSC in cases of OHCA, SHD, or chest compression rate.