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Introduction: The presented study aimed to investigate whether a mechanical chest compression piston device with a suction cup assisting chest recoil could impact the hemodynamic status when compared to a bare piston during cardiopulmonary resuscitation.

Methods: 16 piglets were anesthetized and randomized into 2 groups. After 3 minutes of induced ventricular fibrillation, a LUCAS 3 device was used to perform chest compressions, in one group a suction cup was mounted on the device's piston, while in the other group, compressions were per -formed by the bare piston. The device was used in 30:2 mode and the animals were manually ventilated. Endpoints of the study were: end tidal carbon dioxide, coronary and cerebral perfusion pressures, and brain oxygenation (measured using near infrared spectroscopy). At the end of the protocol, the animals that got a return to spontaneous circulation were observed for 60 minutes, then euthanized.

Results: No difference was found in end tidal carbon dioxide or tidal volumes. Coronary perfusion pressure and cerebral oxygenation were higher in the Suction cup group over the entire experiment time, while cerebral perfusion pressure was higher only in the last 5 minutes of CPR. A passive tidal volume (air going in and out the airways during compressions) was detected and found correlated to end tidal carbon dioxide.

Conclusions: The use of a suction cup on a piston-based chest compression device did not increase end tidal carbon dioxide, but it was associated to a higher coronary perfusion pressure.

BACKGROUND: Ventilation during cardiopulmonary resuscitation (CPR) has long been a part of the standard treatment during cardiac arrests. Ventilation is usually given either during continuous chest compressions (CCC) or during a short pause after every 30 chest compressions (30:2). There is limited knowledge of how ventilation is delivered if it effects the hemodynamics and if it plays a role in the occurrence of lung injuries. The aim of this study was to compare ventilation parameters, hemodynamics, blood gases and lung injuries during experimental CPR given with CCC and 30:2 in a porcine model.

METHODS: Sixteen pigs weighing approximately 33 kg were randomized to either receive CPR with CCC or 30:2. Ventricular fibrillation was induced by passing an electrical current through the heart. CPR was started after 3 min and given for 20 min. Chest compressions were provided mechanically with a chest compression device and ventilations were delivered manually with a self-inflating bag and 12 l/min of oxygen. During the experiment, ventilation parameters and hemodynamics were sampled continuously, and arterial blood gases were taken every five minutes. After euthanasia and cessation of CPR, the lungs and heart were removed in block and visually examined followed by sampling of lung tissue which were examined using microscopy.

RESULTS: In the CCC group and the 30:2 group, peak inspiratory pressure (PIP) was 58.6 and 35.1 cmH₂O (p < 0.001), minute volume (MV) 2189.6 and 1267.1 ml (p < 0.001), peak expired carbon dioxide (PECO₂) 28.6 and 39.4 mmHg (p = 0.020), partial pressure of carbon dioxide (PaCO₂) 50.2 and 61.1 mmHg (p = 0.013) and pH 7.3 and 7.2 (p = 0.029), respectively. Central venous pressure (CVP) decreased more over time in the 30:2 group (p = 0.023). All lungs were injured, but there were no differences between the groups.

CONCLUSIONS: Ventilation during CCC resulted in a higher PIP, MV and pH and lower PECO₂ and PaCO₂, showing that ventilation mode during CPR can affect ventilation parameters and blood gases.

Background

A major barrier to the analysis of ventilation waveform data collected during CPR is the presence of artefacts caused by chest compressions. This study describes the development and evaluation of an algorithm to extract parameters regarding ventilation volume, pressure, and frequency from pneumotachography waveform data collected during ongoing simulated CPR.

Method

Ventilation waveform data was collected from a pneumotachograph connected to the respiratory circuit of a ventilator and a test lung. Both regular ventilation and ventilation during simulated CPR were used to develop the algorithm. A grid search was employed to optimize the algorithm parameters compared to the ventilator settings. The parameters were then manually tuned using clinical data from ventilation during CPR. The performance of the algorithm was described in terms of the median error vs. the known ventilator settings in the simulated data.

Results

Compared to the ventilator settings, the largest systematic errors of the algorithm was an overestimation of peak pressures during asynchronous CPR (median error of 3 (IQR 0.3–5.8) cmH₂O), and an underestimation of inspiratory volumes during synchronous CPR (median error 46 (IQR −76 to 10) ml).

Conclusion

In an experimental setting, the developed algorithm provides a novel solution to measure ventilation parameters during ongoing chest compressions. The algorithm is freely available under an open-source licence for use and further development. Further studies will be needed to validate the algorithm.

Background

Despite the critical role of ventilation in cardiopulmonary resuscitation, scientific understanding of manual ventilation parameters during cardiac arrest is limited, with current cardiopulmonary resuscitation guidelines largely based on expert opinion rather than robust clinical evidence. The aim of this study was to present an extensive description of ventilation during cardiopulmonary resuscitation and ventilation parameters such as volume, pressure and frequency and compare them across different ventilation modes and airway modalities.

Methods

The Cardiac Arrest ventilation study (CAvent) was a multicenter, observational cohort study conducted in both nurse- and physician-staffed advanced life support settings. Key ventilation parameters—such as pressure, volume, and frequency—were captured using a portable pneumotachograph and capnography device. 

Results

The analysis included 28120 ventilations across 311 separate ventilation periods in 241 individual patients, of which 134 received asynchronous ventilations, 86 synchronous and 21 a mix of both. Endotracheal tube was the most frequently used airway modality, used in 58% of the cases. In asynchronous and synchronous ventilation, inspiratory tidal volume, expiratory tidal volume, peak inspiratory pressure and ventilation frequency [DS1] [DS2] was 407 vs. 423 ml, 384 vs. 356 ml, 48.1 vs. 32. 4 and 11.2 vs 5.0 respectively. Bag-valve-mask had the lowest effective lung ventilation and endotracheal tube during asynchronous ventilation had the highest peak inspiratory pressure.

Conclusion

ALS-provided manual ventilation during CPR varies greatly across ventilation modes and airway modalities. The ventilation frequency was higher in asynchronous ventilation while inspiratory tidal volumes did not differ between ventilation modes or modalities. Asynchronous ventilation with an endotracheal tube resulted in the highest peak inspiratory pressure and Bag-valve-mask ventilations in the lowest effective lung ventilation.