Guidelines-recommended tidal volumes are not achieved during continuous mechanical chest compressions—results from a laboratory study

Background: With the continuous chest compressions during cardiac arrest, the pressure in the chest cavity increases. This limits the achievement of tidal volumes as recommended by the guidelines. We aimed to determine the tidal volumes, peak airway pressures and static lung compliance achieved during continuous chest compressions using two different commonly used mechanical devices (Lucas® device and Autopulse® device). Methods: The resuscitation manikin was endotracheally intubated. Mechanical ventilation was performed using a ventilator with the following settings: controlled mechanical ventilation (CMV) mode,inspiratory rate 10 per minute, tidal volume (Vt) 500 mL, inspiratory expiratory time ratio (I:E) 1:5, fraction inspired oxygen (FiO2) 100%, positive end expiratory pressure (PEEP) 0. Lucas® device was used in continuous operation mode and Vt, Peak airway pressure, and static lung compliance (Cstat) were measured during mechanical ventilation for 4 minutes. The same procedure was repeated with the Autopulse® device. Lucas® performs chest compressions on sternum and active decompression. Autopulse® not only compresses the sternum, but also around the chest, and the decompression is passive. Results: The parameters (Vtinsp, Cstat) of 41 breaths were measured during the 4 minutes of simulated continuous chest compressions. When using the Lucas® device, an average tidal volume of 364 mL was achieved, with an average Cstat of 43.6 mL/cmH2O. When using the Autopulse device, an average tidal volume of 240 mL was achieved, while the average Cstat was 29.6 mL/cmH2O. Statistically significant higher tidal volumes were achieved when using the Lucas® device compared to the Auropulse®. Conclusions: Tidal volumes achieved during continuous chest compressions using two devices (Lucas® and Autopulse®) are significantly lower compared to guidelines-recommended tidal volumes, with lower volumes, higher peak airway pressures and higher static compliance measured when using the Autopulse device. Additional meassures should be utilised to assess the effectiveness of ventilations during mechanical chest compressions for cardiac arrest.

Resuscitation; Continuous mechanical chest compression; Tidal volume

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