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Selected Publication:
Wittig, J.
Mechanical Ventilation during External Chest Compressions
Observation of Tidal Volumes during Chest Compressions in the Thiel Human Cadaver Model
Humanmedizin; [ Diplomarbeit ] Medizinische Universität Graz; 2022. pp. 88
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- Authors Med Uni Graz:
- Advisor:
- Orlob Simon
- Prause Gerhard
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- Abstract:
- Introduction Chest compressions and artificial ventilation are cornerstones of cardiopulmonary resuscitation (CPR). However, excessive manual ventilation frequencies can be observed during resuscitation. Excessive ventilation frequencies are associated with reduced survival chances. In contrast, blood gas analyses indicate that hypoventilation is common during CPR. Transport ventilators offer an opportunity to control ventilation frequency. It is unknown how chest compressions impact tidal volumes. This diploma thesis was part of a study investigating whether transport ventilators can produce tidal volumes relevant to gas exchange during continuous chest compressions. Materials and Methods Six human cadavers, embalmed using the Thiel method, served as resuscitation models. Three transport ventilators were studied in a randomized cross-over design of simulated CPR. The models were intubated and received volume-controlled ventilation with a tidal volume of 6 ml/kg ideal predicted bodyweight. During continuous chest compressions, the transport ventilators ‘MEDUMAT Standard2’, ‘Oxylog 3000 plus’, and ‘Monnal T60’ were assessed. Airflow, airway pressure, and esophageal pressure were recorded. Derived volumes and their deviation from the preset tidal volume were calculated and compared. Volume deviation, peak airflow, and airway pressure were analyzed in a linear mixed model. Results 715 ventilations qualified for analysis. The median preset tidal volume was 390 (40, [290; 410]) ml. Median inspiratory tidal volume was 275 (68, [47; 464]) ml. The median deviation from preset tidal volume was −21.2 (19.6, [−87.9; 25.8]) %, corresponding to 4.75 (1.2, [0.7; 7.6]) ml/kg ideal predicted bodyweight. For the ‘MEDUMAT Standard2’ median deviation was −31.5 (16.6, [−56.5; −14.8]) %, −22.7 (22.1, [−70; −12.3]) % for the ‘Oxylog 3000 plus’ and −8.3 (20.5, [−87.9; 25.8]) % for the ‘Monnal T60’. Population estimates of the mixed-linear model were −31 [95%-CI: −38.9; −23] % (p < 0.0001), −30.6 [95%-CI: −38.6; −22.6] % (p < 0.0001), −14.5 [95%-CI: −22.5; −6.5] % (p = 0.0004) for the ‘MEDUMAT Standard2’, ‘Oxylog 3000 plus’ and ‘Monnal T60’ respectively. Conclusion During continuous chest compressions, transport ventilators can provide tidal volumes that exceed dead space ventilation and therefore contribute to gas exchange. However, delivered tidal volumes significantly deviate from preset values. Hence, tidal volumes should be continuously monitored during CPR.