Regurgitation and pulmonary aspiration during cardio-pulmonary resuscitation (CPR) with a laryngeal tube: A pilot crossover human cadaver study

Abstract

Background High-quality chest compressions are imperative for Cardio-Pulmonary-Resuscitation (CPR). International CPR guidelines advocate, that chest compressions should not be interrupted for ventilation once a patient’s trachea is intubated or a supraglottic-airway-device positioned. Supraglottic-airway-devices offer limited protection against pulmonary aspiration. Simultaneous chest compressions and positive pressure ventilation both increase intrathoracic pressure and potentially enhances the risk of pulmonary aspiration. The hypothesis was, that regurgitation and pulmonary aspiration is more common during continuous versus interrupted chest compressions in human cadavers ventilated with a laryngeal tube airway. Methods Twenty suitable cadavers were included, and were positioned supine, the stomach was emptied, 500 ml of methylene-blue-solution instilled and laryngeal tube inserted. Cadavers were randomly assigned to: 1) continuous chest compressions; or, 2) interrupted chest compressions for ventilation breaths. After 14 minutes of the initial designated CPR strategy, pulmonary aspiration was assessed with a flexible bronchoscope. The methylene-blue-solution was replaced by 500 ml barium-sulfate radiopaque suspension. 14 minutes of CPR with the second designated ventilation strategy was performed. Pulmonary aspiration was then assessed with a conventional chest X-ray. Results Two cadavers were excluded for technical reasons, leaving 18 cadavers for statistical analysis. Pulmonary aspiration was observed in 9 (50%) cadavers with continuous chest compressions, and 7 (39%) with interrupted chest compressions (P = 0.75). Conclusion Our pilot study indicate, that incidence of pulmonary aspiration is generally high in patients undergoing CPR when a laryngeal tube is used for ventilation. Our study was not powered to identify potentially important differences in regurgitation or aspiration between ongoing vs. interrupted chest compression. Our results nonetheless suggest that interrupted chest compressions might better protect against pulmonary aspiration when a laryngeal tube is used for ventilation.

Relationship between the regurgitated and the aspirated volume of water. A manikin study

“…Cardio-pulmonary resuscitation is another particular situation at risk of regurgitation and aspiration. Chest compressions combined with positive pressure ventilation both lead to intermittent increased intrathoracic pressures favoring flow of gastric fluid contents towards the esophagus and ultimately to the trachea [18]. In human cadavers with gastric fluid volume of 500 mL, cardio-pulmonary resuscitation performed with the head in the extension position led to pulmonary aspiration in 40% to 60% of cases [18,19].…”

“…Chest compressions combined with positive pressure ventilation both lead to intermittent increased intrathoracic pressures favoring flow of gastric fluid contents towards the esophagus and ultimately to the trachea [18]. In human cadavers with gastric fluid volume of 500 mL, cardio-pulmonary resuscitation performed with the head in the extension position led to pulmonary aspiration in 40% to 60% of cases [18,19]. The use of airway safety devices such as endotracheal intubation is therefore required to secure the airways and minimize the risk of aspiration during cardio-pulmonary resuscitation [19].…”

“…However, the manikin model remains of interest, since experimental studies assessing the part of regurgitated volume that is aspirated into the lungs are not feasible in the living human being. Such studies may be conducted in animals, but these models suffer from important differences as to the anatomical characteristics of the airway compared to humans, while the use of human cadavers also has its own limitations [18][19][20]. Another limitation was that the manikin was placed on a nontilted table.…”

Advanced airway management in out-of-hospital cardiac arrest – to intubate or not to intubate: a narrative review of the existing literature

“…Regurgitation occurs in 1/3 of OHCA; however, this occurs before arrival of emergency medical service staff in at least 2/3 of these cases [39]. Ruetzler et al [40] stated that the incidence of pulmonary aspira tion is generally high in patients undergoing CPR when a laryngeal tube is used for ventilation. Pulmo nary aspiration was observed in seven (39%) cadav ers with interrupted chest compressions and in nine (50%) with continuous chest compressions.…”

Supraglottic airway devices as a method of airway management in prehospital setting

“…The high quality of performed resuscitation not only focuses on activities related to chest compressions and, when needed, defibrillation, but also the proper protection of airways and adequate ventilation. Emphasis is placed on tracheal intubation or supraglottic device incorporation without interrupting chest compressions [3,4].…”