Basic life support with four different compression/ventilation ratios in a pig model: the need for ventilation

Surgical mask-to-mouth ventilation as an alternative ventilation technique during CPR: A crossover randomized controlled trial

INTRODUCTION

Chest compression with rescue breathing improves outcomes in cardiac arrest. However, the efficacy of rescue breathing through surgical masks has not been investigated.

OBJECTIVE

We aimed to compare the tidal volume generated by mouth-to-mouth ventilation (MMV) with that generated by surgical mask-to-mouth ventilation (SMV), mouth-to-surgical mask ventilation (MSV), and surgical mask-to-surgical mask ventilation (SSV) in a manikin.

METHODS

A crossover randomized controlled trial was conducted in 42 medical personnel volunteers randomly assigned to perform four ventilation techniques: MMV (no protective equipment), SMV (participant wearing a mask), MSV (manikin wearing a mask), and SSV, (both participant and manikin wearing a mask). The average tidal volume and the proportion of adequate ventilation, evaluated using a manikin, were compared across different ventilation methods.

RESULTS

The average tidal volume of MMV (828 ± 278 ml) was significantly higher than those of the MSV (648 ± 250 ml, P < 0.001) and SSV (466 ± 301 ml, P < 0.001), but not SMV (744 ± 288 ml, P = 0.054). Adequate ventilation was achieved in 144/168 (85.7%) cases in the MMV group, a proportion significantly higher than in the SMV (77.4%, P = 0.02), MSV (66.7%, P < 0.001) and SSV (39.3%, P < 0.001) groups. The willingness to perform SMV was higher than that to perform MMV.

CONCLUSIONS

MMV resulted in a superior average tidal volume when compared to both MSV and SSV. However, SMV achieved a comparable average tidal volume to MMV.

Analysis of cerebral Interleukin-6 and tumor necrosis factor alpha patterns following different ventilation strategies during cardiac arrest in pigs

Hypoxia-induced neuroinflammation after cardiac arrest has been shown to be mitigated by different ventilation methods. In this prospective randomized animal trial, 35 landrace pigs were randomly divided into four groups: intermittent positive pressure ventilation (IPPV), synchronized ventilation 20 mbar (SV 20 mbar), chest compression synchronized ventilation 40 mbar (CCSV 40 mbar) and a control group (Sham). After inducing ventricular fibrillation, basic life support (BLS) and advanced life support (ALS) were performed, followed by post-resuscitation monitoring. After 6 hours, the animals were euthanized, and direct postmortem brain tissue samples were taken from the hippocampus (HC) and cortex (Cor) for molecular biological investigation of cytokine mRNA levels of Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα). The data analysis showed that CCSV 40 mbar displayed low TNFα mRNA-levels, especially in the HC, while the highest TNFα mRNA-levels were detected in SV 20 mbar. The results indicate that chest compression synchronized ventilation may have a potential positive impact on the cytokine expression levels post-resuscitation. Further studies are needed to derive potential therapeutic algorithms from these findings.

Ventilation in Simulated Out-of-Hospital Cardiac Arrest Resuscitation Rarely Meets Guidelines

OBJECTIVE

The American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care recommend ventilation rates of eight to ten breaths per minute or two ventilations every 30 compressions, and tidal volumes between 500-600 ml. However, compliance with these guidelines is mainly unknown. The objective of this study is to estimate the proportion of simulated adult OHCA cases that meet guideline-based ventilation targets.

METHODS

We conducted a blinded prospective observational study of standardized simulated cases of EMS-witnessed adult OHCA. During scheduled training sessions, resuscitations were performed by high-quality CPR trained EMS teams composed of four on-duty, full-time EMT/Paramedics from a large urban fire-based EMS agency. A high-fidelity simulation center allowed complete audio and video monitoring from a control room. Rescuers were unaware of the study, or that ventilation practices were being observed. All interventions, including airway and ventilation strategies, were at the discretion of the clinical team. A calibrated Laerdal SimMan 3 G manikin and associated Laerdal Debrief Viewer software recorded ventilation rate, tidal volume, and minute ventilation. Simulations achieving median ventilation rate 7-10 breaths/min, tidal volume 500-600 ml, and minute ventilation 3.5-6 liters/min were considered meeting guideline-based targets.

RESULTS

A total of 106 EMS teams were included in the study. Only 3/106 [2.8% (95% CI: 0.6-8.0)] of the EMS teams demonstrated ventilation characteristics meeting all guideline-based targets. The median ventilation rate was 5.8 breaths/min (IQR 4.4-7.7 breaths/min) with 26/106 [24.5% (95% CI: 17.2-33.7)] between 7-10 breaths/min. The median tidal volume was 413.5 ml (IQR 280.5-555.4 ml), with 18/106 [17.0% (95% CI: 10.9-25.5)] between 500-600 ml. The median minute ventilation was 2.4 L/min (IQR 1.2-3.6 L/min) with 16/106 [15.1% (95% CI: 9.4-23.3)] between 3.5-6.0 L/min.

CONCLUSION

During simulated adult OHCA resuscitation attempts, ventilation practices rarely met guideline-based targets, despite being performed by well-trained EMS providers. Methods should be developed to monitor and ensure high-quality ventilation during actual OHCA resuscitation attempts.

A review of ventilation in adult out-of-hospital cardiac arrest

Out-of-hospital cardiac arrest continues to be a devastating condition despite advances in resuscitation care. Ensuring effective gas exchange must be weighed against the negative impact hyperventilation can have on cardiac physiology and survival. The goals of this narrative review are to evaluate the available evidence regarding the role of ventilation in out-of-hospital cardiac arrest resuscitation and to provide recommendations for future directions. Ensuring successful airway patency is fundamental for effective ventilation. The airway management approach should be based on professional skill level and the situation faced by rescuers. Evidence has explored the influence of different ventilation rates, tidal volumes, and strategies during out-of-hospital cardiac arrest; however, other modifiable factors affecting out-of-hospital cardiac arrest ventilation have limited supporting data. Researchers have begun to explore the impact of ventilation in adult out-of-hospital cardiac arrest outcomes, further stressing its importance in cardiac arrest resuscitation management. Capnography and thoracic impedance signals are used to measure ventilation rate, although these strategies have limitations. Existing technology fails to reliably measure real-time clinical ventilation data, thereby limiting the ability to investigate optimal ventilation management. An essential step in advancing cardiac arrest care will be to develop techniques to accurately and reliably measure ventilation parameters. These devices should allow for immediate feedback for out-of-hospital practitioners, in a similar way to chest compression feedback. Once developed, new strategies can be established to guide out-of-hospital personnel on optimal ventilation practices.

Spatial Dynamics of Intercity Technology Transfer Networks in China’s Three Urban Agglomerations: A Patent Transaction Perspective

Technology transfer has become a vital pipeline for acquiring external knowledge. The purpose of this paper is to portray the spatial dynamics of intercity technology transfer networks in China’s three urban agglomerations based on patent right transaction data from 2008 to 2015. The integration of social networks and spatial visualization is used to explore spatial networks and influencing variables of the networks. The results demonstrate that Beijing, Shanghai, and Shenzhen are emerging as hubs in the three urban agglomerations. The spatial distributions of degree and weighted degree are significantly heterogeneous and hierarchical. The larger cities play the role of a knowledge and technology incubator, highly related to their economic scale, research and development (R&D) input, and innovation output. The evolution of intercity technology linkages is driven by the networking mechanisms of preferential attachment, hierarchical and contagious diffusion, path dependence, and path breaking. Moreover, we found that the geographical proximity and technology gaps are determinants of the strength of intercity technology linkages. As a result, it has been discovered that the network in the Beijing–Tianjin–Hebei agglomeration is organized in a tree network, while the Yangtze River Delta features a polycentric network and the Pearl River Delta has multi-star characteristics.

Ventilation during cardiopulmonary resuscitation in children: a survey on clinical practice

BACKGROUND

This study aimed to investigate the ventilation practice during cardiopulmonary resuscitation (CPR) and after return of spontaneous circulation (ROSC) in children.

METHODS

An online survey of CPR practices was designed and sent to healthcare professionals treating children.

RESULTS

A total of 477 healthcare professionals from 46 countries responded to this survey; 92.7% were physicians and 64.2% worked in pediatric intensive care units. Specific CPR guidelines were used by 97.7% of respondents. The respiratory rate most frequently used for children over 12 months was 13 to 20 respirations per minute (rpm) (46% in intubated and 41.8% in non-intubated). For infants under 12 months, the most frequently used respiratory rate was 21 to 30 rpm in intubated patients (37.3%): in non-intubated infants, 13 to 20 rpm (26.5%) and 21 to 30 rpm (26.5%) were used with the same frequency. In North America, the respiratory rate most widely used was 7 to 12 rpm; higher rates (13 to 20 rpm and 21 to 30 rpm) were used in Europe and Latin America (P<0.001). After ROSC, no significant differences in the respiratory rates used were found between the continents. More than 40% of healthcare professionals had a target oxygen saturation below 94%; more than 10% used a target arterial PCO₂ below 35 mmHg and more than 13% above 45 mmHg.

CONCLUSIONS

There is considerable variation in the management of ventilation of children in cardiac arrest, and international recommendations are not being followed in a high percentage of cases.

Dantrolene versus amiodarone for cardiopulmonary resuscitation: a randomized, double-blinded experimental study

Dantrolene was introduced for treatment of malignant hyperthermia. It also has antiarrhythmic properties and may thus be an alternative to amiodarone for the treatment of ventricular fibrillation (VF). Aim of this study was to compare the return of spontaneous circulation (ROSC) with dantrolene and amiodarone in a pig model of cardiac arrest. VF was induced in anesthetized pigs. After 8 min of untreated VF, chest compressions and ventilation were started and one of the drugs (amiodarone 5 mg kg⁻¹, dantrolene 2.5 mg kg⁻¹ or saline) was applied. After 4 min of initial CPR, defibrillation was attempted. ROSC rates, hemodynamics and cerebral perfusion measurements were measured. Initial ROSC rates were 7 of 14 animals in the dantrolene group vs. 5 of 14 for amiodarone, and 3 of 10 for saline). ROSC persisted for the 120 min follow-up in 6 animals in the dantrolene group, 4 after amiodarone and 2 in the saline group (n.s.). Hemodynamics were comparable in both dantrolene group amiodarone group after obtaining ROSC. Dantrolene and amiodarone had similar outcomes in our model of prolonged cardiac arrest, However, hemodynamic stability was not significantly improved using dantrolene. Dantrolene might be an alternative drug for resuscitation and should be further investigated.

Advanced life support and mechanical ventilation

PURPOSE OF REVIEW

Artificial ventilation is one of the best known resuscitation procedures. It is generally accepted that there must be oxygen delivery to vital organs during cardiac arrest and resuscitation in order to prevent irreversible damage, but there is an increasing number of ventilation concepts for resuscitation. Traditional and alternative methods of ventilation are reviewed.

RECENT FINDINGS

The need for positive-pressure ventilation during resuscitation as an essential gold standard might be overestimated at least in the first minutes of cardiopulmonary resuscitation (CPR). The co-founders of the concept of cardiocerebral resuscitation could show positive effects of a sole passive oxygenation at the beginning of advanced life support (ALS). Research was published on continuous positive airway pressure (CPAP) ventilation as well as on CPAP plus pressure support ventilation. In addition to positive-pressure ventilation, the use of an impedance threshold device, partly in addition with active compression-decompression CPR, was investigated in both experimental and clinical settings. None of these methods alone could be proven to improve the outcome of cardiac arrest. The role of high oxygen concentration during CPR also remains unclear.

SUMMARY

Positive-pressure ventilation with pure oxygen remains, in clinical practice, the gold standard in ALS. Further research should focus on the role of passive oxygenation during early ALS. The concentration of oxygen needed during resuscitation has to be defined and alternative ventilation patterns, regarding the impact of CPR, should be investigated.

Chest Compression Synchronized Ventilation versus Intermitted Positive Pressure Ventilation during Cardiopulmonary Resuscitation in a Pig Model

Background

Guidelines recommend mechanical ventilation with Intermitted Positive Pressure Ventilation (IPPV) during resuscitation. The influence of the novel ventilator mode Chest Compression Synchronized Ventilation (CCSV) on gas exchange and arterial blood pressure compared with IPPV was investigated in a pig model.

Methods

In 12 pigs (general anaesthesia/intubation) ventricular fibrillation was induced and continuous chest compressions were started after 3min. Pigs were mechanically ventilated in a cross-over setting with 5 ventilation periods of 4min each: Ventilation modes were during the first and last period IPPV (100% O₂, tidalvolumes = 7ml/kgKG, respiratoryrate = 10/min), during the 2nd, 3rd and 4th period CCSV (100% O₂), a pressure-controlled and with each chest compression synchronized breathing pattern with three different presets in randomized order. Presets: CCSV_A: P_insp = 60mbar, inspiratorytime = 205ms; CCSV_B: P_insp = 60mbar, inspiratorytime = 265ms; CCSV_C: P_insp = 45mbar, inspiratorytime = 265ms. Blood gas samples were drawn for each period, mean arterial (MAP) and centralvenous (CVP) blood pressures were continuously recorded. Results as median (25%/75%percentiles).

Results

Ventilation with each CCSV mode resulted in higher PaO₂ than IPPV: PaO₂: IPPV_first: 19.6(13.9/36.2)kPa, IPPV_last: 22.7(5.4/36.9)kPa (p = 0.77 vs IPPV_first), CCSV_A: 48.9(29.0/58.2)kPa (p = 0.028 vs IPPV_first, p = 0.0001 vs IPPV_last), CCSV_B: 54.0 (43.8/64.1) (p = 0.001 vs IPPV_first, p = 0.0001 vs IPPV_last), CCSV_C: 46.0 (20.2/58.4) (p = 0.006 vs IPPV_first, p = 0.0001 vs IPPV_last). Both the MAP and the difference MAP-CVP did not decrease during twelve minutes CPR with all three presets of CCSV and were higher than the pressures of the last IPPV period.

Conclusions

All patterns of CCSV lead to a higher PaO₂ and avoid an arterial blood pressure drop during resuscitation compared to IPPV in this pig model of cardiac arrest.

Ventilation/perfusion ratios measured by multiple inert gas elimination during experimental cardiopulmonary resuscitation

BACKGROUND

During cardiopulmonary resuscitation (CPR) the ventilation/perfusion distribution (VA /Q) within the lung is difficult to assess. This experimental study examines the capability of multiple inert gas elimination (MIGET) to determine VA /Q under CPR conditions in a pig model.

METHODS

Twenty-one anaesthetised pigs were randomised to three fractions of inspired oxygen (1.0, 0.7 or 0.21). VA/ Q by micropore membrane inlet mass spectrometry-derived MIGET was determined at baseline and during CPR following induction of ventricular fibrillation. Haemodynamics, blood gases, ventilation distribution by electrical impedance tomography and return of spontaneous circulation were assessed. Intergroup differences were analysed by non-parametric testing.

RESULTS

MIGET measurements were feasible in all animals with an excellent correlation of measured and predicted arterial oxygen partial pressure (R(2)  = 0.96, n = 21 for baseline; R(2)  = 0.82, n = 21 for CPR). CPR induces a significant shift from normal VA /Q ratios to the high VA /Q range. Electrical impedance tomography indicates a dorsal to ventral shift of the ventilation distribution. Diverging pulmonary shunt fractions induced by the three inspired oxygen levels considerably increased during CPR and were traceable by MIGET, while 100% oxygen most negatively influenced the VA /Q. Return of spontaneous circulation were achieved in 52% of the animals.

CONCLUSIONS

VA /Q assessment by MIGET is feasible during CPR and provides a novel tool for experimental purposes. Changes in VA /Q caused by different oxygen fractions are traceable during CPR. Beyond pulmonary perfusion deficits, these data imply an influence of the inspired oxygen level on VA /Q. Higher oxygen levels significantly increase shunt fractions and impair the normal VA /Q ratio.

Mechanical ventilation during cardiopulmonary resuscitation with intermittent positive-pressure ventilation, bilevel ventilation, or chest compression synchronized ventilation in a pig model

OBJECTIVE

Mechanical ventilation with an automated ventilator is recommended during cardiopulmonary resuscitation with a secured airway. We investigated the influence of intermittent positive-pressure ventilation, bilevel ventilation, and the novel ventilator mode chest compression synchronized ventilation, a pressure-controlled ventilation triggered by each chest compression, on gas exchange, hemodynamics, and return of spontaneous circulation in a pig model.

DESIGN

Animal study.

SETTING

University laboratory.

SUBJECTS

Twenty-four three-month-old female domestic pigs.

INTERVENTIONS

The study was performed on pigs under general anesthesia with endotracheal intubation. Arterial and central venous catheters were inserted and IV rocuronium (1 mg/kg) was injected. After 3 minutes of cardiac arrest (ventricular fibrillation at t = 0 min), animals were randomized into intermittent positive-pressure ventilation (control group), bilevel, or chest compression synchronized ventilation group. Following 10 minute uninterrupted chest compressions and mechanical ventilation, advanced life support was performed (100% O2, up to six defibrillations, vasopressors).

MEASUREMENTS AND MAIN RESULTS

Blood gas samples were drawn at 0, 4 and 13 minutes. At 13 minutes, hemodynamics was analyzed beat-to-beat in the end-inspiratory and end-expiratory cycle comparing the IPPV with the bilevel group and the CCSV group. Data were analyzed with the Mann-Whitney U test. Return of spontaneous circulation was achieved in five of eight (intermittent positive-pressure ventilation), six of eight (bilevel), and four of seven (chest compression synchronized ventilation) pigs. The results of arterial blood gas analyses at t = 4 minutes and t = 13 minutes (torr) were as follows: PaO2 intermittent positive-pressure ventilation, 143 (76/256) and 262 (81/340); bilevel, 261 (109/386) (p = 0.195 vs intermittent positive-pressure ventilation) and 236 (86/364) (p = 0.878 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 598 (471/650) (p < 0.001 vs intermittent positive-pressure ventilation) and 634 (115/693) (p = 0.054 vs intermittent positive-pressure ventilation); PaCO2 intermittent positive-pressure ventilation, 40 (38/43) and 45 (36/52); bilevel, 39 (35/41) (p = 0.574 vs intermittent positive-pressure ventilation) and 46 (42/49) (p = 0.798); and chest compression synchronized ventilation, 28 (27/32) (p = 0.001 vs intermittent positive-pressure ventilation) and 26 (18/29) (p = 0.004); mixed venous pH intermittent positive-pressure ventilation, 7.34 (7.31/7.35) and 7.26 (7.25/7.31); bilevel, 7.35 (7.29/7.37) (p = 0.645 vs intermittent positive-pressure ventilation) and 7.27 (7.17/7.31) (p = 0.645 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 7.34 (7.33/7.39) (p = 0.189 vs intermittent positive-pressure ventilation) and 7.35 (7.34/7.36) (p = 0.006 vs intermittent positive-pressure ventilation). Mean end-inspiratory and end-expiratory arterial pressures at t = 13 minutes (mm Hg) were as follows: intermittent positive-pressure ventilation, 28.0 (25.0/29.6) and 27.9 (24.4/30.0); bilevel, 29.1 (25.6/37.1) (p = 0.574 vs intermittent positive-pressure ventilation) and 28.7 (24.2/36.5) (p = 0.721 vs intermittent positive-pressure ventilation); and chest compression synchronized ventilation, 32.7 (30.4/33.4) (p = 0.021 vs intermittent positive-pressure ventilation) and 27.0 (24.5/27.7) (p = 0.779 vs intermittent positive-pressure ventilation).

CONCLUSIONS

Both intermittent positive-pressure ventilation and bilevel provided similar oxygenation and ventilation during cardiopulmonary resuscitation. Chest compression synchronized ventilation elicited the highest mean arterial pressure, best oxygenation, and a normal mixed venous pH during cardiopulmonary resuscitation.

Part 10: Pediatric basic and advanced life support: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Note From the Writing Group: Throughout this article, the reader will notice combinations of superscripted letters and numbers (eg, “Family Presence During ResuscitationPeds-003”). These callouts are hyperlinked to evidence-based worksheets, which were used in the development of this article. An appendix of worksheets, applicable to this article, is located at the end of the text. The worksheets are available in PDF format and are open access.