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Effects of anasthesia on esophageal sphincters
Örebro University, School of Health and Medical Sciences.
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The esophageal sphincters constitute the anatomical protection against pulmonary aspiration. The aim of this thesis was to study the esophageal sphincters and how they are affected by different components of emergency anesthesia using high-resolution solid-state manometry.

The effect of propofol (0.3 mg/kg) was studied in young and elderly volunteers. Propofol can be given as an anxiolytic agent for manometric studies of the lower esophageal sphincter (LES) without affecting the results. However, propofol is not recommended for studies of the upper esophageal sphincter (UES).

The effects of cricoid pressure (CP) and peripheral pain were studied in awake volunteers, with and without remifentanil infusion (5 ng/ml). Pain did not affect pressure in the LES, but CP or remifentanil induced a significant decrease in LES pressure. However, neither CP nor remifentanil affected the barrier pressure (LES-intra gastric pressure). When CP was applied during ongoing remifentanil infusion, no further decrease in LES pressure was measured. CP induced high pressures in the area of the UES independent of remifentanil infusion, indicating that CP is effective in preventing gastroesophageal regurgitation.

Barrier pressure was also studied in anesthetized patients after rocuronium (0.6 mg/kg) administration and no decrease was measured. In addition, alfentanil (20 μ/kg) added during anesthesia induction with propofol did not decrease the barrier pressure.

In conclusion, CP seems to be effective in preventing regurgitation and does not affect barrier pressure. Muscle relaxation with rocuronium does not risk gastro-esophageal integrity. In addition, opioids can be integrated, even during emergency anethesia, without increasing the risk for pulmonary aspiration.

Place, publisher, year, edition, pages
Örebro: Örebro universitet , 2011. , p. 50
Series
Örebro Studies in Medicine, ISSN 1652-4063 ; 55
Keywords [en]
Lower esophageal shincter, Upper esophageal sphincter, Barrier pressure, Manometry, Propofol, Remifentanil, Alfentanil, Rocuronium, Cricoid pressure
National Category
Medical and Health Sciences Surgery Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
URN: urn:nbn:se:oru:diva-15271ISBN: 978-91-7668-799-4 (print)OAI: oai:DiVA.org:oru-15271DiVA, id: diva2:410911
Public defence
2011-06-01, Wilandersalen, Universitetssjukhuset Örebro, Örebro, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2011-04-15 Created: 2011-04-15 Last updated: 2017-10-17Bibliographically approved
List of papers
1. Effects of propofol on oesophageal sphincters: a study on young and elderly volunteers using high-resolution solid-state manometry
Open this publication in new window or tab >>Effects of propofol on oesophageal sphincters: a study on young and elderly volunteers using high-resolution solid-state manometry
2011 (English)In: European Journal of Anaesthesiology, ISSN 0265-0215, E-ISSN 1365-2346, Vol. 28, no 4, p. 273-278Article in journal (Refereed) Published
Abstract [en]

BACKGROUND AND OBJECTIVE:

The oesophageal sphincters play an important role in protecting the airway. During manometric studies, administration of an anxiolytic agent is often required to make insertion of the catheter acceptable for the patient. The anxiolytic should not affect the results of the measurements. This study evaluates the effects of two different doses of propofol on the pressures in the oesophageal sphincters. The effect of increased abdominal pressure was also studied.

METHODS:

Twenty healthy volunteers, 10 young (mean age 25 years) and 10 elderly (mean age 71 years), were recruited. The effects of a low dose of propofol [0.3 mg kg(-1) intravenously (i.v.)] and a high dose of propofol (young group 0.9 mg kg(-1) i.v. and elderly group 0.6 mg kg(-1) i.v.) were studied with and without external abdominal pressure.

RESULTS:

There were no statistically significant changes in lower oesophageal sphincter (LOS) pressure after the low dose of propofol. After the high dose, there was an increase in LOS pressure, which was statistically significant in the young group (P < 0.05). The upper oesophageal sphincter (UOS) pressure decreased after both doses of propofol (P < 0.01 for the higher dose and P < 0.05 for the lower dose).

CONCLUSION:

A low dose of propofol (0.3 mg kg(-1) i.v.) leaves the LOS unaffected in young and elderly volunteers and can be used safely as an anxiolytic agent during studies of the LOS without influencing the results. However, the UOS is more sensitive to the effects of propofol and we do not recommend the use of propofol as an anxiolytic agent during manometric studies of the UOS.

Place, publisher, year, edition, pages
Lippincott Williams & Wilkins, 2011
National Category
Medical and Health Sciences Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:oru:diva-15384 (URN)10.1097/EJA.0b013e3283413211 (DOI)000288196000009 ()21119519 (PubMedID)2-s2.0-79953874254 (Scopus ID)
Available from: 2011-04-26 Created: 2011-04-26 Last updated: 2017-12-11Bibliographically approved
2. Effects of cricoid pressure and remifentanil on the esophageal sphincters using high-resolution solid-state manometry
Open this publication in new window or tab >>Effects of cricoid pressure and remifentanil on the esophageal sphincters using high-resolution solid-state manometry
2011 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 55, no 2, p. 209-215Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Cricoid pressure has been shown to decrease the pressure in the lower esophageal sphincter (LES), increasing the risk of aspiration. Whether this reaction is due to pain associated with the application of cricoid pressure has not been studied. The aim of this study was to compare the effects of cricoid pressure with those of peripheral pain on pressures in the LES, and to study whether remifentanil influences these effects. Data from the upper esophageal sphincter (UES) are also described.

METHODS: Continuous solid-state manometry was performed in 14 healthy volunteers. Initially, the effect of remifentanil (target-controlled infusion with a plasma target concentration of 5.0 ng/ml) was studied, and thereafter, the effects of cricoid pressure and peripheral pain stimulation (cold stimulation). Finally, these two interventions were repeated under ongoing remifentanil infusion.

RESULTS: Remifentanil decreased the LES pressure significantly [ΔP-6.5 mmHg, 95% confidence interval (95% CI) -1.7 to -11.2]. Cricoid pressure application decreased the LES pressure significantly (ΔP-3.7 mmHg, 95% CI -1.4 to 6.1), whereas peripheral pain did not (ΔP 1.2 mmHg, 95% CI -3.5 to 1.1). Under ongoing remifentanil infusion, no cricoid pressure-induced LES relaxation was observed. Cricoid pressure induced high pressures in the area of the UES, 215.7 (±91.2) mmHg without remifentanil vs. 219.4 (±74.2) mmHg with remifentanil.

CONCLUSIONS: Remifentanil as well as cricoid pressure per se induced decreases in LES pressure. However, cricoid pressure-induced changes of the barrier pressure were not significant whether induced with or without an infusion of remifentanil.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2011
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:oru:diva-15386 (URN)10.1111/j.1399-6576.2010.02367.x (DOI)000286208600010 ()21226863 (PubMedID)2-s2.0-78651516200 (Scopus ID)
Available from: 2011-04-26 Created: 2011-04-26 Last updated: 2018-02-20Bibliographically approved
3. High resolution solid-state manometry of the effect of rocuronium on esophagogastric junction integrity
Open this publication in new window or tab >>High resolution solid-state manometry of the effect of rocuronium on esophagogastric junction integrity
(English)Manuscript (preprint) (Other academic)
Abstract [en]

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 pressure in the LES and the barrier pressure (LES pressure – intra gastric pressure). We also studied the effect of positive pressure ventilation on the barrier pressure after neuromuscular blockade with rocuronium.

Methods: Fourteen patients classified as 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 after anesthetization with propofol, fentanyl and sevoflurane. After the insertion of a laryngeal mask airway, the patients breathed spontaneously for one minute. Rocuronium was administrated and the patients observed during the onset of apnea and during one minute of apnea and complete neuromuscular blockade. Volume controlled positive pressure ventilation followed.

Results: Muscle relaxation with rocuronium showed no significant changes in barrier pressure comparing the pressure immediately before rocuronium administration with the pressure obtained at the time point of 0% 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)

National Category
Medical and Health Sciences Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:oru:diva-15387 (URN)
Available from: 2011-04-26 Created: 2011-04-26 Last updated: 2017-10-17Bibliographically approved
4. Integrity of the esophagogastric junction during propofol induction with and without remifentanil: a double-blind,randomized, crossover study in volunteers
Open this publication in new window or tab >>Integrity of the esophagogastric junction during propofol induction with and without remifentanil: a double-blind,randomized, crossover study in volunteers
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Context: Practice varies regarding the use of opioids during rapid sequence induction. Controversy exists as to whether opioids may increase the risk of pulmonary aspiration by decreasing the barrier pressure (lower oesophageal sphincter pressure – intragastric pressure).

Objectives: To evaluate the effects of adding alfentanil during anaesthesia induction with propofol with respect to the barrier pressure in the oesophagogastric junction.

Participants and Setting: Seventeen healthy volunteers (11 males and 6 females) participated in a double-blind, randomised, crossover trial at the University Hospital in Örebro, Sweden.

Interventions and outcome measures: The volunteers were anaesthetised on two different occasions, randomly assigned to receive either alfentanil 20 g kg ˉ1 or an equivalent amount of saline, administered intravenously, one minute before induction with propofol 2 mg kg ˉ1. One minute after propofol administration, a cricoid pressure of 30N was applied. The primary outcome was the difference in the change in barrier pressure between the alfentanil and the placebo occasion one minute after propofol administration. The secondary outcomes were differences in the changes in barrier pressure one minute after alfentanil or placebo administration and during ongoing cricoid pressure application.

Results: There were no statistically significant differences in barrier pressure, at any time point, between anaesthesia induction with alfentanil and propofol compared with induction with placebo and propofol. The barrier pressure never decreased to less than 2.4 mmHg in any volunteer.

Conclusion: Our study showed no increased risk regarding the integrity of the gastrooesophageal junction when alfentanil is added during an induction with propofol in volunteers. This supports the practice of adding opioids as adjuvants during rapid sequence induction.

National Category
Medical and Health Sciences Anesthesiology and Intensive Care
Research subject
Anaesthesiology
Identifiers
urn:nbn:se:oru:diva-15388 (URN)
Available from: 2011-04-26 Created: 2011-04-26 Last updated: 2017-10-17Bibliographically approved

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