Barrier pressure and muscle relaxants. Comparison of the effects of pancuronium and vecuronium on the lower oesophageal sphincter

Impact of anesthesia drugs on digestive motility measurements in humans: A systematic review

BACKGROUND AND PURPOSE

Measurement of gastro-intestinal motility is increasingly performed under general anesthesia during endoscopic or surgical procedures. The aim of the present study was to review the impact of different anesthetic agents on digestive motility measurements in humans.

METHODS

This systematic review was performed using the Medline-Pubmed and Web of Science databases. All articles published until October 2023 were screened by identification of key words. Studies were reviewed if patients had an assessment of digestive motility using conventional perfused manometry, high-resolution manometry, electronic barostat or functional lumen impedance planimetry with the use of inhaled or intravenous anesthetic anesthetic agents (propofol, ketamine, halogens, nitrous oxide, opioids, and neuromuscular blockades).

RESULTS

Four hundred and eighty-eight unique citations were identified, of which 42 studies met the inclusion criteria and were included in the present review. The impact of anesthetics was mostly studied in patients who underwent esophageal manometry. There was a heterogeneity in both the dose and timing of administration of anesthetics among the studies. Remifentanil analgesia was the most studied anesthetic drug in the literature, showing a decrease in both distal latency and lower esophageal sphincter pressure after its administration, but the impact on Chicago classification was not studied. Inhaled anesthetics administration elicited a decrease in lower esophageal sphincter pressure, but contradictory findings were shown on esophageal motility following propofol or neuromuscular blocking agents administration.

CONCLUSION

Studies of the impact of anesthetics on digestive motility remain scarce in the literature, although some agents have been reported to profoundly affect gastro-intestinal motility.

High-resolution solid-state manometry of the effect of rocuronium on barrierpressure

BACKGROUND

The pressure in the lower esophageal sphincter (LES) is partly dependent on striated muscles derived from the crural portion of the diaphragm. The effect of neuromuscular blockade on the integrity of the esophagogastric junction is not well studied. We conducted a prospective interventional study to determine the effect of rocuronium on the barrier pressure (LES pressure - intragastric pressure) of the esophagogastric junction. We also studied the effect of positive pressure ventilation on the barrier pressure after neuromuscular blockade with rocuronium.

METHODS

Fourteen patients classified as American Society of Anesthesiologists classification system (ASA) I or II (aged 18-75 years) who presented for elective surgery (11 cholecystectomy, 3 inguinal hernia) participated in the study. Esophageal manometry was performed during anesthetization with propofol, fentanyl, and sevoflurane. The LES pressure was studied prior to anesthesia, after anesthesia induction during spontaneous breathing with laryngeal mask airway, after administration of rocuronium (0.6 mg/kg), and during positive pressure ventilation.

RESULTS

Muscle relaxation with rocuronium showed no significant changes in barrier pressure when comparing the pressure immediately before rocuronium administration with the pressure obtained after rocuronium administration at the time point of 0% train-of-four (TOF). Conversion to positive pressure ventilation did not change the barrier pressure with inspiration or expiration. The greatest decrease in barrier pressure was measured after inducing anesthesia when comparing pressures during inspiration (P < 0.01).

CONCLUSIONS

Neuromuscular blockade with rocuronium and conversion from spontaneous breathing to positive pressure ventilation does not decrease the barrier pressure during anesthesia induction.

Effect of laryngeal mask airway on esophageal motility during general anesthesia

STUDY OBJECTIVES

To determine whether the Laryngeal Mask Airway (LMA) triggers the pharyngo-esophago-gastric reflex during general anesthesia by comparing the esophageal motility of patients with the LMA and endotracheal tube (ETT) in place.

DESIGN

Randomized clinical trial.

SETTING

Operating room and recovery room of a tertiary-care referral hospital.

PATIENTS

50 adult ASA physical status I and II patients scheduled for elective orthopedic surgery.

INTERVENTIONS

All patients received a standardized general anesthetic technique, then were allocated randomly to the LMA (n = 30) or ETT (n = 20) groups.

MEASUREMENTS AND MAIN RESULTS

The esophageal manometric inputs were recorded continuously using an ambulatory esophageal manometric recorder and divided into five perioperative phases (preanesthesia, induction, surgery, LMA, or ETT rejection and arousal phase). The LMA or ETT was removed at the end of the surgery, when the patient was awake. An awake state was defined as the presence of the following clinical signs: swallowing, bucking, struggling, straining, and restlessness. The esophageal peristaltic wave percent and esophageal contraction frequency were significantly decreased during induction, surgery, and the LMA or ETT rejection and arousal phases compared with the preanesthetic phases in both the LMA and ETT groups. However, there were no significant group differences in any corresponding perioperative phases.

CONCLUSION

During the general anesthetic period before the arousal phase in this study, a LMA does not provoke significantly different esophageal peristalsis compared with an ETT. Thus, the LMA is unlikely to stimulate the pharyngo-esophago-gastric reflex during that period.

Intraoperative manometry to assess the esophagogastric junction during laparoscopic fundoplication and myotomy

SUMMARY

Surgery for gastroesophageal reflux disease and achalasia is performed to alleviate symptoms by improving esophagogastric junction (EGJ) function. Intraoperative manometry was used to evaluate the pressure-length characteristics of the reconstructed EGJ during laparoscopic Nissen fundoplication and laparoscopic Heller myotomy. Intraoperative manometry was performed in 37 consecutive patients undergoing laparoscopic Nissen fundoplication (n = 22) or laparoscopic Heller myotomy (n = 15). Measurements were taken before surgery, after creation of the pneumoperitoneum, after completion of the myotomy in achalasia, and after creation of the fundoplication. Tracings were analyzed for pressure, length, and the integrated pressure-length relation (area under the curve [AUC]). Statistical comparison was made using paired t tests; intraoperative EGJ measurements did not correlate well with preoperative values for either pressure or length. Laparoscopic Nissen fundoplication significantly increased pressure, length, and AUC of the EGJ compared with prefundoplication values. Laparoscopic Heller myotomy significantly decreased EGJ pressure, length, and AUC. Creation of a Toupet fundoplication after myotomy did not significantly increase pressure, length, and AUC of the EGJ compared with postmyotomy values. Intraoperative manometry identified 2 of 15 achalasia patients (13%) with persistent areas of high pressure after initial myotomy that were corrected by extending the myotomy. Intraoperative manometry identifies mechanical changes created during EGJ surgery and may be a useful adjunct to improve outcomes of laparoscopic Nissen fundoplication and laparoscopic Heller myotomy.

[Effects of anesthesia on the lower sphincter of the esophagus]

The lower oesophageal sphincter (LOS) is the most important structure preventing regurgitation of gastric contents, with the risk of tracheobronchial aspiration, as it occurs in cases of laryngeal incompetence in connection with general anaesthesia. This article reviews anatomical data, means of assessment of the sphincter function, as well as the effects of anaesthetic agents and situations carrying a high risk of regurgitation and tracheobronchial aspiration.