Original contributionEffectiveness of various airway management techniques in a bench model simulating a cardiac arrest patient1
Introduction
Endotracheal intubation is the gold standard to secure the airway, but this may not always be possible (1). For example, although paramedics are trained to perform an emergent endotracheal intubation, they may not perform this maneuver frequently or on a daily basis. Thus, if a paramedic is not able to correctly perform endotracheal intubation, alternate airway management employing a self-inflatable bag, laryngeal mask, or Combitube may be needed (2). Because of unfavorable respiratory mechanics during cardiopulmonary resuscitation (CPR), such as decreased lower esophageal sphincter pressure and respiratory system compliance, bag-valve-mask ventilation has been recognized as a ventilation strategy that is associated with significant levels of gastric inflation 3, 4, 5, 6. Hence, if an airway adjunct that paramedics are able to handle safely when endotracheal intubation is not possible, and that is more effective than bag-valve-mask ventilation, can be identified, the quality of emergency airway management might be improved. The laryngeal mask and Combitube are airway devices that could serve as justifiable alternatives to endotracheal intubation 7, 8, 9, 10, 11, 12, 13, 14, 15, 16. We have previously validated a bench model simulating an unintubated cardiac arrest patient with precisely specified components, such as the respiratory system compliance, lower esophageal sphincter pressure, and airway resistance 5, 7, 8. Accordingly, this is a useful tool to evaluate ventilation strategies that are almost impossible to evaluate during scene calls by the emergency medical service (EMS).
The purpose of the present study was to assess what levels of lung and gastric tidal volumes paramedics achieve when employing ventilation with bag-valve-mask ventilation, a laryngeal mask, and Combitube in the aforementioned bench model simulating an unintubated cardiorespiratory arrest patient. Our null hypothesis was that there would be no difference in study endpoints among groups.
Section snippets
Experimental model
A bench model simulating an unintubated cardiac arrest patient was designed to compare the effects of ventilation by using a bag-valve-face mask, the laryngeal mask, and the Combitube. It consists of a new intubation manikin head (Bill I, VBM Medizintechnik, Sulz, Germany) and a lung simulator (LS 800, Dräger, Lübeck, Germany). Lung compliance was adjusted at 50 mL/cm H2O and airway resistance at 16 cm H2O/L/s to simulate the respiratory mechanics of a patient with cardiorespiratory arrest 4, 17
Results
Twenty paramedics performed simulated emergency ventilation on the bench model by using the bag-valve-mask, the laryngeal mask airway, and the Combitube. With two volunteers, the ventilation attempt failed with bag-valve-mask ventilation, whereas the other 18 participants delivered the first adequate tidal lung volume in [minimum – maximum (median) seconds] 4–20 (9) s with the bag-valve-mask, 17–101 (35) s with the laryngeal mask, and 5–73 (48) s with the Combitube. No ventilation failures
Discussion
In a bench model of a simulated intubated patient with cardiorespiratory arrest, professional paramedics achieved excellent lung tidal volumes when using a laryngeal mask or the Combitube, but not when employing a bag-valve-mask. Accordingly, bag-valve-mask ventilation resulted in significant gastric inflation, whereas the laryngeal mask caused only minor, and the Combitube no, gastric inflation at all.
In contrast to an optimally prepared and fasting patient in the operating room, patients with
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2014, American Journal of Emergency MedicineCitation Excerpt :In the present study, the success rate of CLMA placement was rather high. Some studies report similar success rates to our results [10,13,14,27-29], whereas other studies report extremely lower success rates [19,24,30,31]. These differences might be attributed to the fact that studies are not conducted under uniform settings, for example they may differ in their design, or in the manikins used [32].
Effects of bag-mask versus advanced airway ventilation for patients undergoing prolonged cardiopulmonary resuscitation in pre-hospital setting
2012, Journal of Emergency MedicineCitation Excerpt :However, bag-mask ventilation can produce gastric inflation with complications including regurgitation, aspiration, and pneumonia. Gastric inflation can elevate the diaphragm, restrict lung movement, and decrease respiratory system compliance (3–5). On the other hand, advanced airway ventilation (eg, endotracheal tube, esophageal-tracheal combitube, or laryngeal mask airway) may be more advantageous during prolonged cardiopulmonary resuscitation (CPR).
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2011, Journal of Clinical AnesthesiaCitation Excerpt :Moreover, early placement of Laryngeal Mask Airways (LMAs) results in lower gastric insufflation volumes. Use of a LMA may reduce the entrained esophageal air [10]; however, whether this procedure would have led to a significant decrease in entrained esophageal air in this case is unknown. Facemask ventilation may be a difficult skill to master and require two individuals, with one participant using his hands to provide a more efficient face mask seal and jaw thrust.
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The authors do not have a conflict of interest in regards to the devices used in this experiment.