Lower Esophageal Sphincter Pressure During Prolonged Cardiac Arrest and Resuscitation☆,☆☆,★,★★
Section snippets
INTRODUCTION
Prompt establishment of adequate ventilation is a primary concern in the management of cardiac arrest. In the unprotected airway, the delivered tidal volume depends on several factors, including lung compliance, adequacy of mask seals, flow rate, and gastric distension. Gastric insufflation occurs when air enters the stomach and can lead to regurgitation and pulmonary aspiration1. The lower esophageal sphincter (LES) is a pressure-sensitive valve that limits gastric insufflation and reflux in
MATERIALS AND METHODS
Our protocol was approved by the University of Pittsburgh Animal Care and Use Committee. Eighteen female mixed-breed domestic swine were used; their mean mass was 21.9±1.7 kg. The animals were sedated with IM ketamine (10 mg/kg) and xylazine (1 mg/kg). Each was then anesthetized intravenously with a loading dose of 40 mg/kg a-chl oralose followed by a maintenance infusion of 10 mg/kg/hour. Each animal was then orotracheally intubated with a 5-0 cuffed endotracheal tube and mechanically
RESULTS
The mean baseline LES tone was 20.6±2.8 cm H 2O. This baseline value resembles the values found in human beings under general anesthesia, indicating that ours may be an appropriate model. LES pressure values during the arrest and after ROSC are given in Table 1.LES pressure decreased steadily during the 7 minutes of VF but was significantly reduced during minutes 2 through 7 compared with the baseline value (all comparisons, P<.01). ROSC occurred in 10 of the 18 trials. After ROSC, LES pressure
DISCUSSION
Lung compliance in human beings is poor during cardiac arrest.4 This fact is important in that air introduced by means of positive-pressure ventilation tends to bypass the lungs and take the path of least resistance. With an LES pressure lower than that previously reported during cardiac arrest, it is likely that larger volumes of air than previously reported would enter the stomach rather than ventilate the lungs.
The American Heart Association Guidelines for Cardio-pulmonary Resuscitation
CONCLUSION
In this swine model, we found the baseline value of LES pressure to be comparable to the 20 cm H 2O found in human beings under general anesthesia. However, LES tone decreased rapidly when VF was induced. Even after ROSC occurred, LES tone reached a plateau at a level about half that at baseline during the observation period. Further studies of the decay of LES tone during human cardiac arrest and its effects on mask ventilation and gastric insufflation are warranted.
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Cited by (116)
It's time to learn more about the “P” in CPR
2023, ResuscitationAirway management in out-of-hospital cardiac arrest: A systematic review and network meta-analysis
2023, American Journal of Emergency MedicineCitation Excerpt :However, there are some shortcomings in the early stage of SGA placement, such as laryngeal spasm, air leakage, low lung compliance, invalid chest stiffness, and poor protection against gastric reflux. [19-21] BM is easier to initiate, and has been used many years as the primary airway management, but still has some problems too(e.g., regurgitation of gastric contents, aspiration, intragastric perfusion of oxygen). [22,23] Based on the currently available evidence, the optimal airway management methods during OHCA is still debated.
Gastric insufflation during cardiopulmonary resuscitation: A study in human cadavers
2020, ResuscitationCitation Excerpt :First, the cadaveric model is not entirely comparable to a real cardiac arrest patient. However, the lower esophageal opening pressure reported in the present study is higher than previously described immediately after death25,26 and this may have interfered with our results by limiting gastric insufflation. Second, the method we used to assess gastric insufflation along time, previously reported by Segal et al.24 (i.e., a surgical gastrostomy) may have limited stomach distension because the gastrostomy works as a leak, and result in a lower impact on ventilation.
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From the Center for Emergency Medicine of Western Pennsylvania* and the Division of Medicine, School of Medicine, University of Pittsburgh,‡ Pittsburgh Pennsylvania.
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Funded by the Pittsburgh Emergency Medicine Foundation and the Center for Emergency Medicine of Western Pennsylvania.
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Address for reprints: James J Menegazzi, PhD, Center for Emergency Medicine, 230 McKee Place, Suite 500, Pittsburgh, Pennsylvania 15213, 412-578-3235, Fax 412-578-3241
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Reprint no. 47/1/66265