Experimental paperEffects of stomach inflation on haemodynamic and pulmonary function during spontaneous circulation in pigs☆
Introduction
Stomach inflation may occur with increasing peak airway pressure during routine induction of anaesthesia while ventilating an unprotected airway.1 While stomach inflation during daily routine induction of anaesthesia may indicate a lack of appreciation of the problem “elevated peak airway pressure”, the component of haemodynamic, pulmonary and lower oesophageal dysfunction is added in emergency patients. This adverse combination may in turn render stomach inflation during bag-valve-mask ventilation even more likely.2 For example, paramedics ventilated patients on the street with high ventilation rates, resulting in increased intrathoracic pressure.3 While elevated intrathoracic pressure due to hyperventilation had severe adverse effects on haemodynamic parameters during cardiopulmonary resuscitation (CPR),3 it is unclear if elevated intra-abdominal pressure due to inadvertent stomach inflation may impair haemodynamic and pulmonary function as well. Recently, we reported adverse effects of stomach inflation on haemodynamic and pulmonary function during CPR.4 Also, two cases of cardiac arrest that were related to massive stomach inflation have been reported.5, 6 Thus, this phenomenon may be important to recognise since stomach inflation regardless of its cause in critically ill patients, for example during shock or cardiac arrest, is very likely,7 which may have, in turn, implications on postresuscitation care.
The purpose of this study was to evaluate the effect of gradually increasing stomach inflation on haemodynamic and pulmonary function during spontaneous circulation in a porcine model. The null hypothesis was that stomach inflation would have no influence on haemodynamic and pulmonary function.
Section snippets
Materials and methods
This project was approved by the Austrian Federal Animal Investigation Committee, and animals were managed in accordance with the American Physiologic Society, institutional, and Utstein-style guidelines,8 and the position of the American Heart Association on Research Animal Use. Animal care was performed by qualified individuals and supervised by veterinarians. All facilities and transportation comply with current legal requirements and meet the standards of the American Association for
Results
Before stomach inflation haemodynamic and pulmonary parameters were comparable between groups (Fig. 1, Fig. 2, Fig. 3, Fig. 4). After 22.5 min, i.e. 8.5 L in the 0.5 L and 17 L in the 1 L stomach inflation group, stomach inflation increased central venous pressure, mean pulmonary artery pressure, and pulmonary capillary wedge pressure (Fig. 1). As a result stroke volume index decreased (Fig. 1). Also, stomach inflation decreased static pulmonary compliance, but increased airway resistance and peak
Discussion
In an unprotected airway, ∼50% of applied minute ventilation usually enters the stomach.10 When extrapolating this observation to a 70 kg patient being ventilated with ∼5, ∼2.5 L/min stomach inflation may result, or 1.25 L/min stomach inflation in a 40 kg pig as in our study. To simulate different stomach inflation levels, we employed a moderately (0.5 L steps) and excessively (1 L steps) increasing stomach inflation group. While it is unclear whether large amounts of gas causing stomach inflation
Conflict of interest
No author has any financial or personal relationships with other people or organisations that could inappropriately influence this work.
Acknowledgments
Supported, in part, by the Science foundation of the Austrian National Bank grant 11448, Vienna, Austria. We are indebted to Fritz Zschiegner, Christof Mittermair and Daniel Pehböck for technical expertise.
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It's time to learn more about the “P” in CPR
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A ventilation technique for oxygenation and carbon dioxide elimination in CPR: Continuous insufflation of oxygen at three levels of pressure in a pig model
2015, ResuscitationCitation Excerpt :Our data, which shows higher mean airway pressure combined with higher oxygenation, supports both their data and this theory, demonstrating that alternative techniques may be useful in creating improved oxygenation even under low blood flow conditions and without compromising CPP. Other studies have reported that excessively high intrathoracic and mean and peak airway pressures negatively affect oxygenation through deteriorating (pulmonary) haemodynamics.9,19,20 The adequate oxygenation with TLPV indicates that the pressures with TLPV were adequate for supporting haemodynamic and pulmonary function.
The impact of airway management on quality of cardiopulmonary resuscitation: An observational study in patients during cardiac arrest
2014, ResuscitationCitation Excerpt :There were also non-significant increases in average inflation time after airway insertion in both LMA (p = 0.888) and ETT group (p = 0.787). These trends may reflect deteriorating pulmonary compliance which is seen when the duration of the resuscitation attempt increases.26,27 Average change in impedance between start and top of ventilation and was measured in ohms.
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A Spanish translated version of the summary of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2009.01.005.
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Died in July 2008.