The effects of premedication drugs on the lower oesophageal high pressure zone and reflux status of rhesus monkeys and man

The Effect of Premedication on the Incidence of Gastroesophageal Reflux in 270 Dogs Undergoing General Anesthesia

The aim of this prospective, non-randomized study was to evaluate the effect of nine different premedication medications on the incidence of gastroesophageal reflux (GOR) in anesthetized dogs. Two hundred and seventy dogs undergoing non-intrathoracic, non-intrabdominal elective surgeries or invasive diagnostic procedures were included in the study, and were allocated into nine groups (30 dogs/group) defined by the type of premedication administered. Premedication consisted of dexmedetomidine with either morphine, pethidine or butorphanol, acepromazine with either one of the three opioids or midazolam with one of the above-mentioned opioids. Anesthesia was induced with propofol and maintained with isoflurane in oxygen. Esophageal pH was measured with the use of a pH-meter electrode and a pH-value less than 4 and over 7.5 was considered to be GOR. The study revealed that 119/270 (44.1%) dogs experienced a reflux episode during anesthesia. The incidence of reflux did not differ among groups (p = 0.117). In group AB the dogs refluxed within 10 min of the beginning of pH-measurements, in comparison with group DB in which dogs refluxed within 30 min (p = 0.029). Invasive diagnostic procedures had a lower incidence of GOR in comparison to castrations (p = 0.09). The outcome of the study suggests that none of the opioids used increased the incidence of GOR in anesthetized dogs.

Perianesthetic mortality in English Bulldogs: a retrospective analysis in 2010 - 2017

Background

Many veterinarians consider English Bulldogs to have a greater perianesthetic mortality risk. The aims of this study were to 1) determine total and anesthesia-related, perianesthetic mortality (PAM) rates in English Bulldogs (EB), 2) identify potential risk factors associated with mortality in EB, and 3) determine the difference in the perianesthetic mortality rates between EB, other-brachycephalic breeds (OB), and non-brachycephalic breeds (NB).

Records from EB that were anesthetized between 2010 and 2017, were investigated. OB and NB were enrolled to match with each EB based on a procedure and age from the study period. Data collected in EB included: age, ASA status, weight, procedure types, anesthetic and analgesic management, anesthetic duration, anesthetic recovery location, and cause of death. Age and cause of death were determined from OB and NB. Fisher’s exact test was used to compare PAM rate and age in EB, OB, and NB. Mann–Whitney U test was used to compare EB survivor and EB non-survivor. Logistic regression models were used to identify factors and odds ratio (OR) associated with PAM in EB.

Result

Two hundred twenty nine EB, 218 OB, and 229 NB were identified. The total and anesthesia-related PAM rates in EB were 6.6 and 3.9%, respectively. EB had a greater total PAM rate compared with OB (p = 0.007). ASA status was different between survivors and non-survivors in EB (p < 0.01). Risk factors identified regardless of the cause of death were premedication with full μ opioids (OR = 0.333, p = 0.114), continuous infusion of ketamine post-operatively (OR = 13.775, p = 0.013), and acepromazine administration post-operatively (OR = 7.274, p = 0.004). The most common cause of death in EB was postoperative respiratory dysfunction (87.5%).

Conclusion

Total and anesthesia-related mortality in EB is considerable. Most deaths in EB occurred during the postoperative period secondary to respiratory complications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03301-9.

Benzodiazepines or related drugs and risk of pneumonia: A systematic review and meta-analysis

OBJECTIVE

Benzodiazepines and benzodiazepine-related drugs (BZRDs) are used to treat various psychiatric diseases. However, there are concerns that BZRDs increase the risk of pneumonia.

METHODS

We performed a systematic review and meta-analysis of observational studies to determine whether BZRD use affects the risk of pneumonia. Our analysis included all observational studies that compared pneumonia development among patients receiving BZRD vs those with no treatment.

RESULTS

In total, 12 citations of 10 studies involving more than 120,000 pneumonia cases were included in our meta-analysis. After pooling the estimates, the odds for developing pneumonia were 1.25-fold higher (odd ratio, OR = 1.25; 95% confidence interval (CI), 1.09-1.44) in BZRD users compared with individuals who had not taken BZRD. On the basis of exposure window, we found an increased risk of pneumonia among current (OR = 1.4; 95%CI, 1.22-1.6) and recent (OR = 1.38; 95%CI, 1.06-1.8) users, but not with the past users (OR = 1.11; 95%CI, 0.96-1.27).

CONCLUSION

Current or recent exposure to BZRD is associated with an increased pneumonia risk. Clinicians need to weight the benefit-risk balance of BZRD use, especially those with other risk factors for pneumonia.

Achalasia: It Is Not All Black and White

PURPOSE OF REVIEW

This review aims to shed light on subtleties of achalasia diagnosis, including potential pitfalls that may lead to errors. Optimal methods for assessment of disease severity and the relationship between achalasia and other motility disorders will also be reviewed with an emphasis on recent findings from the literature.

RECENT FINDINGS

Adjunctive testing with viscous substances or larger water volumes should be used routinely as it improves the accuracy of achalasia diagnosis. Chronic opiate use can mimic achalasia. The timed barium swallow remains the best test for assessments of disease severity and prognostication, but the functional lumen-imaging probe, a newer tool which measures esophagogastric junction distensibility using impedance planimetry, is emerging as a potentially more powerful tool for these purposes. Functional esophagogastric junction outflow obstruction is possibly part of the achalasia spectrum. By addressing the potential pitfalls described, and through routine and standardized use of the diagnostic tools mentioned herein, the accuracy of diagnosis, severity assessment, and prognostication of achalasia can be improved.

Cricoid Pressure Controversies

Since cricoid pressure was introduced into clinical practice, controversial issues have arisen, including necessity, effectiveness in preventing aspiration, quantifying the cricoid force, and its reliability in certain clinical entities and in the presence of gastric tubes. Cricoid pressure–associated complications have also been alleged, such as airway obstruction leading to interference with manual ventilation, laryngeal visualization, tracheal intubation, placement of supraglottic devices, and relaxation of the lower esophageal sphincter. This review synthesizes available information to identify, address, and attempt to resolve the controversies related to cricoid pressure. The effective use of cricoid pressure requires that the applied force is sufficient to occlude the esophageal entrance while avoiding airway-related complications. Most of these complications are caused by excessive or inadequate force or by misapplication of cricoid pressure. Because a simple-to-use and reliable cricoid pressure device is not commercially available, regular training of personnel, using technology-enhanced cricoid pressure simulation, is required. The current status of cricoid pressure and objectives for future cricoid pressure–related research are also discussed.

Evaluation of Esophageal Motility Utilizing the Functional Lumen Imaging Probe

OBJECTIVES

Esophagogastric junction (EGJ) distensibility and distension-mediated peristalsis can be assessed with the functional lumen imaging probe (FLIP) during a sedated upper endoscopy. We aimed to describe esophageal motility assessment using FLIP topography in patients presenting with dysphagia.

METHODS

In all, 145 patients (aged 18-85 years, 54% female) with dysphagia that completed upper endoscopy with a 16-cm FLIP assembly and high-resolution manometry (HRM) were included. HRM was analyzed according to the Chicago Classification of esophageal motility disorders; major esophageal motility disorders were considered "abnormal". FLIP studies were analyzed using a customized program to calculate the EGJ-distensibility index (DI) and generate FLIP topography plots to identify esophageal contractility patterns. FLIP topography was considered "abnormal" if EGJ-DI was <2.8 mm²/mm Hg or contractility pattern demonstrated absent contractility or repetitive, retrograde contractions.

RESULTS

HRM was abnormal in 111 (77%) patients: 70 achalasia (19 type I, 39 type II, and 12 type III), 38 EGJ outflow obstruction, and three jackhammer esophagus. FLIP topography was abnormal in 106 (95%) of these patients, including all 70 achalasia patients. HRM was "normal" in 34 (23%) patients: five ineffective esophageal motility and 29 normal motility. In all, 17 (50%) had abnormal FLIP topography including 13 (37%) with abnormal EGJ-DI.

CONCLUSIONS

FLIP topography provides a well-tolerated method for esophageal motility assessment (especially to identify achalasia) at the time of upper endoscopy. FLIP topography findings that are discordant with HRM may indicate otherwise undetected abnormalities of esophageal function, thus FLIP provides an alternative and complementary method to HRM for evaluation of non-obstructive dysphagia.

A “Light Meal” Three Hours Preoperatively Decreases the Incidence of Gastro-Esophageal Reflux in Dogs

Emerging evidence from veterinary and medical clinical research shows that reducing preoperative fasting time may reduce the incidence of gastro-esophageal reflux (GER) intraoperatively. In order to evaluate the effect of two different preoperative fasting times on the incidence of GER during general anesthesia, 120 dogs were randomly assigned to two groups: administration of canned food 3 h before premedication (group C3, n = 60) and administration of canned food 10 h before premedication (group C10, n = 60). The animals were premedicated with propionyl-promazine. Anesthesia was induced with thiopental sodium and maintained with halothane. A pH electrode was introduced into the esophagus, and the esophageal pH was constantly monitored. Esophageal pH of less than 4 or greater than 7.5 was taken as an indication of GER. Three of the 60 dogs of group C3 and 12 of the 60 dogs of group C10 experienced a GER episode, the difference being statistically significant (P = .025). Feeding the dog 3 h before anesthesia at a half daily rate reduces significantly the incidence of GER during anesthesia, compared to the administration of the same amount and type of food 10 h before anesthesia. The administration of a half daily dose of an ordinary canine diet may be useful in clinical practice.

Achalasia and chronic opiate use: innocent bystanders or associated conditions?

High-resolution manometry identifies three subtypes of achalasia. However, type 3 differs from classic achalasia. Although opiates affect esophageal motility, opiate use and achalasia have not been studied. Patients with a new diagnosis of achalasia at Mayo Clinic Rochester between June 1, 2012 and January 3, 2014 were identified. Clinical records were reviewed to assess symptoms, opiate use, and therapy. Fifty-six patients with achalasia were identified, 14 (25%) were on opiates. Opiate prescription was unrelated to achalasia in all cases, with chronic back and joint pain constituting the majority. Of patients on opiates, five (36%) had type 3 achalasia compared with four (10%) not on opiates (P = 0.02). No patients on opiates had type 1 achalasia. Clinical presentation did not differ with opiates, although those on opiates were more likely to report chest pain (39 vs. 14%, P = 0.05) and less likely to have esophageal dilation (62 vs. 82%, P = 0.13), none with greater than 5-cm diameter. Contractile vigor was greater with opiate use, with distal contractile integral of 7149 versus 2615.5 mmHg/cm/second (P = 0.08). Treatment response was inferior on opiates, with persistent symptoms in 22% compared with 3% without opiates (P = 0.06). Opiate use is common in type 3 achalasia, with the majority of patients on opiates. No patients on opiates were diagnosed with type 1 achalasia. Manometric findings of type 3 achalasia mimic those induced by opiates, suggesting a physiologic mechanism for opiate induced type 3 achalasia. Treatment outcome is inferior with opiates, with opiate cessation perhaps preferable. Further studies assessing opiate use and achalasia are needed.

Effects of morphine and midazolam on pharyngeal function, airway protection, and coordination of breathing and swallowing in healthy adults

BACKGROUND

Drugs used for sedation in anesthesia and intensive care may cause pharyngeal dysfunction and increased risk for aspiration. In this study, the authors investigate the impact of sedative doses of morphine and midazolam on pharyngeal function during swallowing and coordination of breathing and swallowing.

METHODS

Pharyngeal function, coordination of breathing and swallowing, and level of sedation were assessed by manometry, videoradiography, measurements of respiratory airflow, and a visual analog scale in 32 healthy volunteers (age 19 to 35 yr). After baseline recordings, morphine (0.1 mg/kg) or midazolam (0.05 mg/kg) was administered intravenously for 20 min, followed by recordings at 10 and 30 min after the end of infusion.

RESULTS

Pharyngeal dysfunction, seen as misdirected or incomplete swallowing or penetration of bolus to the airway, increased after morphine infusion to 42 and 44% of swallows compared with 17% in baseline recordings. Midazolam markedly increased incidence of pharyngeal dysfunction from 16 to 48% and 59%. Morphine prolonged apnea before swallowing, and midazolam increased the number of swallows followed by inspiration.

CONCLUSION

Morphine and midazolam in dosages that produce sedation are associated with increased incidence of pharyngeal dysfunction and discoordinated breathing and swallowing, a combination impairing airway protection and potentially increasing the risk for pulmonary aspirations.

Aspiration Induced by Remifentanil

Background:

Remifentanil is widely used for monitored anesthesia care in spontaneously breathing patients. However, the authors’ previous studies have shown that remifentanil induces subjective swallowing difficulties, which may increase the risk of aspiration.

Methods:

Twenty-five healthy volunteers participated in a double-blind, randomized, crossover trial at the University Hospital in Örebro, Örebro, Sweden. The volunteers were studied on two different occasions during which they received either remifentanil with an effect-site target concentration of 3 ng/ml or saline over 1 h. A radionuclide tracer was infused simultaneously into the nasopharynx at a rate of 0.1 ml/min. Aspiration was determined by lung scans, and subjective swallowing difficulties and grip strength were evaluated. The primary outcome was the difference in occurrence of aspiration between remifentanil and placebo treatments. The secondary outcomes were differences in swallowing difficulty and grip strength and the association between aspiration and swallowing difficulty.

Results:

During remifentanil and placebo infusion, 48 and 12% of the volunteers aspirated, respectively, difference: 36% (95% CI, 10 to 62%). A similar significant difference was found for swallowing difficulties but not for the association between aspiration and swallowing. No difference was found in grip strength between the two treatments.

Conclusions:

Remifentanil infusion at concentrations used in monitored anesthesia care increases the incidence of aspiration. However, the subjective swallowing difficulty induced by remifentanil is not indicative of the aspiration risk.

Effects of remifentanil on the esophagogastric junction and swallowing

BACKGROUND

A recent study demonstrated that reflux is associated with impaired pressure augmentation in the esophagogastric junction (EGJ), caused by diaphragmal contractions during inspiration. It is unknown whether this augmentation is influenced by opioids. Swallowing difficulties can be a poorly recognised side effect of remifentanil. Here, we investigated whether remifentanil influences inspiratory EGJ augmentation and evaluated subjective swallowing difficulties induced by remifentanil. We also used the peripheral opioid receptor antagonist methylnaltrexone to evaluate whether these effects are centrally or peripherally mediated.

METHODS

Ten healthy volunteers participated in a double-blind, randomised, cross-over trial at the University Hospital in Örebro, Sweden. They were studied on two different occasions, during which they were randomly assigned to receive either methylnaltrexone 0.15 mg/kg or saline subcutaneously 30 min before the target-controlled infusion of remifentanil of 3 ng/mL. EGJ pressures were measured by high-resolution manometry. Swallowing difficulties were assessed when volunteers performed dry swallows. The outcomes were the differences in EGJ pressures at baseline and during remifentanil infusion and with methylnaltrexone vs. placebo. Differences in swallowing difficulties before and during remifentanil, and with methylnaltrexone vs. placebo were also recorded.

RESULTS

Remifentanil decreased the inspiratory EGJ augmentation and induced swallowing difficulties. No statistically significant differences between methylnaltrexone and placebo occasions were found.

CONCLUSIONS

Remifentanil may increase risk for gastroesophageal reflux by decreasing the inspiratory EGJ augmentation. The clinical significance of remifentanil-induced swallowing difficulties is to be studied further. Given the limited sample size, it cannot be concluded whether these effects are centrally or peripherally mediated.

Esophagogastroduodenoscopy with conscious sedation does not interfere with catheter-based 24-h pH monitoring

AIM: To investigate the impact of esophagogastroduodenoscopy with conscious sedation on the subsequent 24-h catheter-based pH monitoring.

METHODS: Fifty patients with extra-esophageal symptoms of gastroesophageal reflux disease undergoing ambulatory dual-probe 24-h pH monitoring were enrolled from March 2010 to August 2011. All of the data were collected prospectively and analyzed retrospectively. Thirty-six patients (72%, group A) underwent pH monitoring shortly after esophagogastroduodenoscopy (EGD) with conscious sedation, and 14 patients (28%, group B) underwent pH monitoring without conscious sedation. The 24-h pH data from two time periods were analyzed: the first 4 h (Period I) and the remaining time of the study (Period II).

RESULTS: The mean age of the patients was 49.6 ± 12.5 years; 20 patients (40%) were men. The baseline data, including age, sex, body mass index, reflux esophagitis, the Reflux Symptom Index, and the Reflux Findings Score, were comparable between the two groups. The percentage of total time with a pH < 4 and the frequency of acid reflux during Period I were not significantly different between the two groups, as measured using both pharyngeal (0.03% ± 0.10% vs 0.07% ± 0.16%, P = 0.32; and 0.07 ± 0.23 episodes/h vs 0.18 ± 0.47 episodes/h, P = 0.33, respectively) and esophageal probes (0.96% ± 1.89% vs 0.42% ± 0.81%, P = 0.59; and 0.74 ± 1.51 episodes/h vs 0.63 ± 0.97 episodes/h, P = 0.49, respectively). The percentage of total time with a pH < 4 and the frequency of acid reflux were also not significantly different between Periods I and II in group A patients, as measured using both pharyngeal (0.03% ± 0.10% vs 0.23% ± 0.85%, P = 0.21; and 0.07 ± 0.23 episodes/h vs 0.29 ± 0.98 episodes/h, P = 0.22, respectively) and esophageal probes (0.96% ± 1.89% vs 1.11% ± 2.57%, P = 0.55; and 0.74 ± 1.51 episodes/h vs 0.81 ± 1.76 episodes/h, P = 0.55, respectively).

CONCLUSION: EGD with conscious sedation does not interfere with the results of subsequent 24-h pH monitoring in patients with extra-esophageal symptoms of gastroesophageal reflux disease.

Ambulatory esophageal pHmetry in healthy dogs with and without the influence of general anesthesia

This research aimed to determine the value of esophageal pH in awake and anesthetized dogs, to evaluate the esophageal pH value in awake dogs, in different body positions, as well as to study the occurrence of gastroesophageal reflux episodes in these positions. Thus, 40 healthy male and female adult dogs with mean body weight of 15.5 ± 4.6 kg were used. Esophageal pHmetry was conducted by inserting a catheter through the oropharynx in 30 dogs (stage 1) anesthetized with acepromazine, propofol and isoflurane, submitted to elective ovariosalpingohysterectomy. In addition, 8-h esophageal pHmetry was carried out transnasally in 10 awake dogs (stage 2), allowed to move and change body positions (lateral and sternal decubitus, and standing position), which were recorded. The mean esophageal pH value was lower (p < 0.01) in the anesthetized dogs (7.3 ± 0.82) than in the awake dogs (8.2 ± 0.3). Only four anesthetized dogs (13.33%) suffered reflux episodes. Reflux was not observed in the awake dogs and no esophageal pH differences were found between the body positions studied. Compared to the alert state, general anesthesia in dogs submitted to the previously mentioned anesthesia protocol causes esophageal pH reduction and predisposes to the occurrence of gastroesophageal reflux episodes. Transnasal pHmetry of 8 h in healthy awake dogs reveals that the esophageal pH value is alkaline and does not vary according to body position. In these animals, decubitus position is not a determining factor for reflux episodes to occur.

Effects of cricoid pressure and remifentanil on the esophageal sphincters using high-resolution solid-state manometry

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.

Gastroesophageal reflux disease and sleep disorders: evidence for a causal link and therapeutic implications

Gastroesophageal reflux disease (GERD) and sleep disturbances are both common health problems. There is a significant association between disturbed sleep and GERD, and this may be bidirectional. Sleep disorders may induce gastrointestinal (GI) disturbances, while GI symptoms also may provoke or worsen sleep derangements. Reflux of gastric acid is a less frequent event during sleep, however, acid clearance mechanisms (including swallowing, salivation and primary esophageal motility) are impaired during sleep resulting in prolongation of acid contact time. Nighttime reflux can lead to sleep disturbance and sleep disturbance may further aggravate GERD by prolonged acid contact time and heightened sensory perception. This may facilitate the occurrence of complicated GERD and decreased quality of life. However, the interplay between sleep problems and GERD is complex, and there are still relatively limited data on this issue. Further investigation of sleep-related GERD may identify common pathophysiological themes and new therapeutic targets.

Meta-analyses of hypnotics and infections: eszopiclone, ramelteon, zaleplon, and zolpidem

STUDY OBJECTIVES

Recent meta-analyses raising concern about risks of hypnotics suggest a need for more clarification of these risks.

METHODS

Because of preliminary suggestions that eszopiclone causes infections, we studied US Food and Drug Administration files on the 4 most-recently approved hypnotics, combined with published studies, to compile the risk ratios of infections for groups randomly assigned to receive hypnotics versus those assigned to receive placebos in controlled trials. Parallel controlled clinical trials of eszopiclone, ramelteon, zaleplon, and zolpidem were included when data on subjects, duration of exposure, and adverse effects were available. Results of trials were combined by meta-analyses.

RESULTS

Of 8828 participants assigned to the 4 hypnotics and 4383 participants who randomly received placebos, 606 in the hypnotics groups and 200 in the placebo groups were reported to develop some kind of infection (risk ratio = 1.44, 95% confidence interval 1.25-1.64, p < 0.00001). Most infections were apparently mild and did not lead to dropouts. Subanalyses for individual drugs indicated that eszopiclone and zolpidem individually were associated with reported infections. There were insufficient data concerning individual studies of zaleplon and ramelteon for valid secondary meta-analyses of zaleplon or ramelteon by themselves.

CONCLUSIONS

Research is needed to objectively determine whether the use of hypnotics increases the risk of infections. Immune compromise or esophageal reflux and aspiration should be studied as possible mechanisms.

Pre-anesthetic meperidine: associated vomiting and gastroesophageal reflux during the subsequent anesthetic in dogs

OBJECTIVE

To determine the effect of meperidine administered prior to anesthesia on the incidence of vomiting before, and gastroesophageal reflux (GER) and regurgitation during, the subsequent period of anesthesia in dogs.

STUDY DESIGN

Randomized, controlled trial.

ANIMALS

A total of 60 healthy dogs, 4.3 +/- 2.3 years old, and weighing 35.5 +/- 13.1 kg.

METHODS

Dogs were admitted to the study if they were healthy, had no history of vomiting, and were scheduled to undergo elective orthopedic surgery. The anesthetic protocol used was standardized to include thiopental and isoflurane in oxygen. Dogs were randomly selected to receive one of the following pre-medications: morphine (0.66 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM), meperidine (8.8 mg kg(-1) IM) with acepromazine (0.044 mg kg(-1) IM) or meperidine alone (8.8 mg kg(-1) IM). A sensor-tipped catheter was placed to measure esophageal pH during anesthesia. Gastro-esophageal reflux was judged to have occurred if there was a decrease in esophageal pH below four or an increase above 7.5.

RESULTS

No dogs vomited after the administration of meperidine, but 50% of dogs vomited after the administration of morphine. When compared with morphine, treatment with meperidine alone or combined with acepromazine before anesthesia was associated with a 55% and 27% reduction in absolute risk of developing GER, respectively. Dogs receiving meperidine alone were significantly less sedate than other dogs in the study, and required more thiopental to induce anesthesia. Arterial blood pressure and heart rate were not significantly different between groups at the start of the measurement period. Cutaneous erythema and swelling were evident in four dogs receiving meperidine.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of meperidine to healthy dogs prior to anesthesia was not associated with vomiting and tended to reduce the occurrence of GER, but produced less sedation when compared with morphine. Meperidine is not a useful addition to the anesthetic protocol if prevention of GER is desired.

Influence of metoclopramide on gastroesophageal reflux in anesthetized dogs

OBJECTIVE

To determine the effect of 2 doses of metoclopramide on the incidence of gastroesophageal reflux (GER) in anesthetized dogs.

ANIMALS

52 healthy dogs undergoing elective orthopedic surgery.

PROCEDURE

In this prospective clinical study, dogs were evaluated before and during orthopedic surgery. The anesthetic protocol used was standardized to include administration of acepromazine, morphine, thiopental, and isoflurane. Dogs were randomly selected to receive an infusion of saline (0.9% NaCl) solution, a low dose of metoclopramide, or a high dose of metoclopramide before and during anesthesia. Treatment groups were similar with respect to age, body weight, duration of food withholding before surgery, duration of surgery, and dose of thiopental administered. Dogs were positioned in dorsal recumbency during surgery. A sensor-tipped catheter was inserted to measure esophageal pH during anesthesia. We defined GER as a decrease in esophageal pH to < 4 or an increase to > 7.5 that lasted more than 30 seconds.

RESULTS

The high dose of metoclopramide (bolus loading dose of 1.0 mg/kg, IV, followed by continuous infusion at a rate of 1.0 mg/kg/h) was associated with a 54% reduction in relative risk of developing GER. The low dose did not significantly affect the incidence of GER.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of metoclopramide by bolus and constant rate infusion at doses much higher than commonly used will reduce the incidence but not totally prevent GER in anesthetized dogs undergoing orthopedic surgery.

The effects of cricoid pressure, remifentanil, and propofol on esophageal motility and the lower esophageal sphincter

Cricoid pressure is the gold standard during the induction of anesthesia when there is a risk of aspiration of gastric contents. However, the effect of cricoid pressure during the different steps of complete anesthesia induction has not been studied. The purpose of this study was to investigate the effects of cricoid pressure, remifentanil, and propofol on lower esophageal sphincter (LES) and esophageal motility. We recorded LES pressure (LESP) and calculated barrier pressure ([BrP] = LESP - gastric pressure) in 10 healthy volunteers using a Dent sleeve device. There was a significant decrease in LESP and BrP when a cricoid pressure of 30 N was performed in the awake volunteers (P < 0.05). However, this effect was not seen during the infusion of remifentanil 0.2 microg . kg(-1) . min(-1). Remifentanil per se or together with a bolus dose of propofol 1 mg/kg IV did not induce any statistical change in LESP or BrP. Remifentanil abolished spontaneous esophageal motility and completely eliminated the experience of discomfort induced by cricoid pressure. In conclusion, cricoid pressure of 30 N induced a decrease of LESP and BrP in awake volunteers. These effects were not seen during the remifentanil infusion. This shows the importance of when to apply cricoid pressure during rapid-sequence induction.

Clinical presentation, diagnosis, and management of gastroesophageal reflux disease

GERD is ubiquitous throughout the adult population in the United States. It commonly adversely affects quality of life and occasionally causes life-threatening complications. The new and emerging medical and endoscopic therapies for GERD and the new management strategies for BE should dramatically reduce the clinical toll of this disease on society.

Effects of preanesthetic administration of morphine on gastroesophageal reflux and regurgitation during anesthesia in dogs

OBJECTIVE

To determine the effect of morphine administered prior to anesthesia on the incidence of gastroesophageal reflux (GER) in dogs during the subsequent anesthetic episode.

ANIMALS

90 dogs (30 dogs/group).

PROCEDURE

The randomized prospective clinical study included healthy dogs with no history of vomiting. Dogs were scheduled to undergo elective orthopedic surgery. Food was withheld for (mean+/-SD) 17.8+/-4.1 hours prior to induction of anesthesia. The anesthetic protocol included acepromazine maleate, thiopental, and isoflurane. Dogs were randomly selected to receive morphine at various dosages (0, 0.22, or 1.10 mg/kg, IM) concurrent with acepromazine administration prior to induction of anesthesia. A sensor-tipped catheter was used to measure esophageal pH, and GER was defined as a decrease in pH to < 4 or an increase to > 7.5.

RESULTS

40 dogs had acidic reflux, and 1 had biliary reflux. Proportions of dogs with GER were 8 of 30 (27%), 15 of 30 (50%), and 18 of 30 (60%) for morphine dosages of 0, 0.22, and 1.10 mg/kg, respectively. Mean duration of GER was 91.4+/-56.8 minutes. There was no significant association between GER and age, weight, vomiting after preanesthetic medication, administration of antimicrobials, or start of surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Most healthy dogs vomit after a large dose of morphine, but vomiting does not increase the likelihood of GER during the subsequent anesthetic episode. Administration of morphine prior to anesthesia substantially increases the incidence of GER during the subsequent anesthetic episode.

Midwifery dilemma: to fast or feed the labouring woman. Part I: The case for restricting oral intake in labour

This paper presents a literature review which pursues both sides of the labouring woman's oral intake debate--to fast or to feed the labouring woman. Part 1 provides an exploration of the phenomenon of gastric content aspiration associated with general anaesthesia and its historical and physiological underpinnings. Part 2 provides an examination of the literature concerning the benefits of fasting labouring women.

Evaluation of lower oesophageal sphincter pressure using endoscopic manometric sleeve assembly

BACKGROUND

The purpose of this study was to establish a method to determine lower oesophageal sphincter (LOS) pressure using an endoscopic manometric sleeve assembly.

METHODS

We used a 250-cm, three-lumen, 2.2-mm external diameter silicon catheter with a 3-cm sleeve sensor that was passed easily through the biopsy channel (2.8 mm diameter) of the gastroscope. Each lumen was perfused with distilled water using a low-compliance, pneumohydraulic capillary infusion system. Forty-seven healthy subjects and 35 patients with oesophageal disorders underwent study during routine diagnostic endoscopy. In 27 of the subjects, standard transnasal manometry with a three-lumen, 4.5-mm diameter polyvinyl catheter with a 5-cm sleeve sensor was also performed.

RESULTS

Lower oesophageal sphincter pressure (LOS) was evaluated in all subjects (median pressure 16 mmHg, range 0-55 mmHg) for 6 min during routine endoscopic examination. The LOS pressure readings between standard and endoscopic manometry correlated well. The LOS pressure was significantly lower in healthy subjects with hiatal hernia than in those without hernia and was also significantly lower in patients with reflux oesophagitis than in healthy subjects.

CONCLUSIONS

Endoscopic manometric sleeve assembly was used during routine endoscopic examination and was useful for easily determining LOS pressure. It could be used for evaluation of oesophageal motility disorders, thus avoiding the use of a more invasive and time-consuming method.

Gastric emptying and intestinal transit times of radiopaque markers in cats fed a high-fiber diet with and without low-dose intravenous diazepam

Reference ranges for gastric emptying time (GET), small intestinal transit time (SITT), and colonic transit time of 1.5-mm and 5-mm radiopaque markers in healthy cats fed a high-fiber meal were determined, and the influence of low-dose diazepam intravenous injection on the gastrointestinal transit of the markers was examined. The mean GETs and SITTs, and the mean residence times (MRTs) and geometric centers (GCs) of markers in the colon were determined. The effect of intravenous diazepam injection and marker size on these parameters was examined. Diazepam injection had no significant influence on gastrointestinal transit. The GETs of the 1.5-mm markers were significantly more rapid than those of the 5.0-mm markers. There were no significant differences between the SITTs or GCs of the 1.5-mm and 5.0-mm markers. Reference values were developed for GET, SITT, and colonic transit of radiopaque markers for cats fed a high-fiber meal. Diazepam injection had no effect on these parameters.

Lower oesophageal sphincter tone increases after induction of anaesthesia in pigs with full stomach

PURPOSE

The lower oesophageal sphincter (LOS) is the man mechanism that prevents gastro-oesophageal regurgitation during anaesthesia. The aim of this study was to assess the effect on lower oesophageal sphincter pressure (LOSP) of rapid sequence induction in pigs with full stomachs.

METHODS

Lower oesophageal sphincter pressure and oesophageal barrier pressure (BrP = LOSP minus gastric pressure) were measured using a water-perfused manometric catheter method in 12 pigs after gastric filling with 500 ml of liquid nutrient mixture. Six pigs were randomly allocated to receive 5 mg.kg-1 propofol and 3 mg.kg-1 succinylcholine i.v. and six pigs received 8 mg.kg-1 thiopentone and 3 mg.kg-1 succinylcholine i.v.

RESULTS

After induction, mean LOSP increased during the period with fasciculations from 19 +/- 4 mmHg to 28 +/- 5 mmHg in the propofol-succinylcholine group and from 23 +/- 6 mmHg to 36 +/- 7 mmHg in the thiopentone-succinylcholine group. The LOSP remained elevated after the fasciculations. LOSP and BrP were not different between the groups.

CONCLUSIONS

Induction of anaesthesia with propofol-succinylcholine or thiopentone-succinylcholine increases LOSP and, consequently, BrP in pigs with a full stomach. This increase begins before fasciculations and remains elevated for the period when intubation would occur.

Gastroesophageal reflux and tracheobronchial contamination after cardiac surgery: should a nasogastric tube be routine?

Nasogastric (NG) tubes are routinely used in patients undergoing cardiac surgery. This randomized study was designed to assess gastroesophageal reflux (GER) without a NG tube (control) compared with a NG tube managed either by gravity drainage (gravity) or continuous low-grade suction (suction). Antimony pH probes were placed in the lower esophagus and trachea after induction of anesthesia in 51 patients, and pH was recorded every 5 s until the time of tracheal extubation. GER was defined as reversible decrease in esophageal pH to less than 4.0. No significant difference was found between groups in age, weight, gender, duration of postoperative ventilation, morphine use, or antiemetic use. All indicators of GER were seen more frequently in the gravity group compared with the two other groups (P < 0.001). One episode of sudden decrease in tracheal pH was observed in a patient in the gravity group, indicating tracheal aspiration, which was associated with delayed extubation and postoperative pneumonia. The absence of a NG tube is not associated with reflux, probably since the gastroesophageal sphincter remains competent. NG tubes are not routinely necessary for cardiac surgery in patients without risk factors for GER, and increase reflux risk if managed without low-grade suction.

Cricoid pressure decreases lower oesophageal sphincter tone in anaesthetized pigs

PURPOSE

Previous studies have shown a decrease of lower oesophageal sphincter (LOS) tone during stimulation of the upper oesophageal sphincter. Therefore, we hypothesized that during anaesthesia, cricoid pressure could result in a decrease in LOS pressure.

METHODS

The LOS and oesophageal barrier pressures (BrP = LOSP minus gastric pressure) were obtained in 11 anaesthetized pigs with intraabdominal pressure of 15 mmHg using a manometric method (perfused catheters) before and during firm application of cricoid pressure. Reflux was assessed with concomitant recording of the lower oesophageal pH.

RESULTS

Cricoid pressure decreased LOSP from 31.0 +/- 14.5 mmHg to 26.1 +/- 12.7 mmHg (P < 0.001) leading to a 35% reduction of oesophageal barrier pressure (9 +/- 10.3 mmHg vs 13.7 +/- 12.4 mmHg; P < 0.001). No episodes of reflux were recorded.

CONCLUSIONS

This study shows that cricoid pressure decreases LOS tone in anaesthetized pigs. Although no gastrooesophageal reflux was recorded, this study suggests that, if cricoid pressure does not completely occlude the oesophagus, the decrease of oesophageal barrier pressure induced could favour the appearance of pulmonary aspiration.

The effect of increase in end-tidal carbon dioxide on lower esophageal sphincter tone

The lower esophageal sphincter is composed of smooth muscles and is the main barrier against regurgitation during anesthesia. As smooth muscles are usually sensitive to CO2, we investigated the response of lower esophageal sphincter pressure to varying concentrations of CO2 in six anesthetized pigs using a manometric method. CO2 was increased by increasing the dead space at the Y piece of the ventilator. Basal values for ETCO2 were 35 +/- 2 mm Hg, reaching 62 +/- 1 mm Hg at the end of the study (P < 0.03). In response to the increase in ETCO2, no change in lower esophageal sphincter pressure was noted (12 +/- 3 mm Hg vs 13 +/- 4 mm Hg). These findings indicate that the lower esophageal sphincter is not affected by CO2 in the range usually encountered in clinical practice.

[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.

Lower oesophageal sphincter hypersensitivity to opioid receptor stimulation in patients with idiopathic achalasia

Impairment of non-cholinergic innervation of the lower oesophageal sphincter has been suggested in idiopathic achalasia. As opioid nerves are present in the lower oesophageal sphincter and opioid peptides affect lower oesophageal sphincter motility, the effect of an opioid agonist, morphine (100 micrograms/kg iv), and an opioid blocker, naloxone (80 micrograms/kg iv), on lower oesophageal sphincter motor function was assessed in 10 healthy subjects and in 10 patients with untreated idiopathic achalasia on separate days and in randomised order. In addition, in six of the patients, naloxone 0.8 mg iv was injected 60 minutes after morphine and recordings continued for a further five minutes. Lower oesophageal sphincter pressure was monitored by a sleeve device. In the healthy subjects morphine decreased (p < 0.01) resting lower oesophageal sphincter pressure by 4 (1) mm Hg (23 (8)%). In the achalasia patients the effect was more marked, lower oesophageal sphincter pressure being reduced (p < 0.01) by 11 (2) mm Hg (46 (8)%). Naloxone reversed lower oesophageal sphincter pressure to basal. Both absolute and percentage decreases after morphine were significantly greater (p < 0.05) in the achalasia patients than in the healthy subjects. Swallow induced lower oesophageal sphincter relaxation was significantly decreased (p < 0.05) by morphine in the healthy subjects but not in the achalasia patients. Naloxone had no effect on resting lower oesophageal sphincter pressure or swallow induced relaxation in either healthy subjects or achalasia patients. In conclusion achalasia patients are hypersensitive to the effect of morphine on resting lower oesophageal sphincter pressure. This finding is unlikely to be the result of a denervation process involving opioid nerves.

[Gastroesophageal reflux with combined caudal and halothane anesthesia in children]

Sixteen children, aged 2 to 5 years and ranked ASA 1, were included in this study assessing gastro-oesophageal reflux occurring under halothane anaesthesia, before and during, caudal anaesthesia. They were scheduled for surgery below the umbilicus lasting 1 to 5 h. After premedication with oral hydroxyzine (2 mg.kg-1) and intravenous atropine (10 micrograms.kg-1), induction was carried out with 3% halothane. A gastro-oesophageal pH probe was inserted via the nose after calibration at 37 degrees C. A neutral pH for the oesophageal electrode and an acid pH for the gastric one demonstrated the correct position of the probe. The pH was then registered every 4 s. The probe was left in situ until the patient left the recovery room. The caudal anaesthesia catheter was then inserted with the patient lying on his left side. Caudal anaesthesia was began with 2.5 mg.kg-1 of plain bupivacaine and 5 mg.kg-1 of plain lidocaine. When the patient was lying supine again, narcosis was maintained with 0.5% halothane and 50% nitrous oxide. A dose of 1.5 mg.kg-1 of bupivacaine was injected every 30 to 45 min. None of the children displayed any respiratory signs (coughing, dyspnoea, bronchospasm, cyanosis) during the combined anaesthetic. Two episodes of asymptomatic gastro-oesophageal reflux were revealed by this method, one lasting 7 minutes and occurring during insertion of the caudal catheter, and the other, lasting 4 minutes, during recovery. There were no pulmonary sequels. There was excellent respiratory and haemodynamic stability throughout. The two episodes seemed to have been triggered off by rapid displacement of the patient and too deep an anaesthetic.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intravenous diazepam on esophageal motility in normal subjects

Controversy exists over whether diazepam can be used for sedation during esophageal manometry studies without affecting the results. To evaluate the effect of diazepam, 20 healthy asymptomatic volunteers were studied using a standard manometry protocol employing an Arndorfer capillary infusion system. Following a baseline manometry, each subject received 0.1 mg/kg diazepam intravenously over 1 min and underwent repeat manometry 5 min after completion of the injection. All manometry recordings were coded and read blindly. The amplitude of the lower esophageal sphincter was significantly reduced by diazepam from 26.2 +/- 10.9 and 30.0 +/- 10.9 mm Hg to 18.8 +/- 7.6 and 24.5 +/- 9.7 mm Hg by rapid and station pull-through methods, respectively (P less than 0.01 both methods). Esophageal contraction wave duration was significantly increased following diazepam at 3, 8, and 13 cm above the lower esophageal sphincter (P less than 0.01 all levels). There was a trend toward increased contraction wave amplitude following diazepam administration in the lower three fourths of the esophagus. On the basis of these results, we conclude that diazepam sedation may produce misleading results when used during esophageal manometric testing. It is recommended that diazepam not be used in manometric studies of normal subjects or patients with reflux esophagitis and that manometric findings in patients with hypertensive or spastic disorders be interpreted with caution if diazepam is given as a premedication.

Risk-benefit assessment of anaesthetic agents in the puerperium

A critical evaluation of anaesthetic agents in the puerperium is difficult because systematic, relevant studies are still lacking. Current knowledge of the effects of different agents used in labour and caesarean section indicates that significant residual effects on the mother and newborn are limited. In the early puerperium, based on physiological and/or hormonal changes, the mother could be more sensitive to inhalational anaesthetic agents and local analgesics. To date there is no evidence that any anaesthetic agent is excreted in breast milk in clinically significant amounts when given as a single dose. The only exception is perhaps in the case of very premature neonates whose mothers have had multidrug therapy before labour. Even then the importance of breast milk should be carefully assessed against possible adverse drug effect. However, repeated administration of long-acting benzodiazepines and continuous epidural administration of pethidine (meperidine) can have adverse effects on the neonate. The essential conclusion of this review is that breast-feeding is best. The different anaesthetic agents are excreted in the milk in amounts so low that detrimental effects on the neonate should not be expected.

Oxybutynin-induced reflux esophagitis

Oxybutynin has less anticholinergic activity than propantheline bromide. Therefore, oxybutynin is often preferentially prescribed for patients at risk of morbid complications of atropine-like adverse effects. We report a case of oxybutynin-induced reflux esophagitis. This probably resulted from the anticholinergic action of oxybutynin, which decreased lower esophageal sphincter tone. We outline a management approach for patients who experience this adverse effect due to oxybutynin or other commonly prescribed medications.

Sufentanil is preferable to etomidate during rapid-sequence anesthesia induction for aortocoronary bypass surgery

To evaluate rapid-sequence anesthetic induction techniques for aortocoronary bypass grafting, 20 patients scheduled for elective surgery were randomly assigned to receive bolus injections of either etomidate, 0.4 mg/kg, intravenously (IV), or sufentanil, 5 micrograms/kg, IV, with succinylcholine, 1 mg/kg, IV. Patients in the two groups had similar demographic characteristics and baseline (preinduction) hemodynamic values. Following induction and intubation, 8 of 9 etomidate patients required a pharmacologic intervention to treat hypertension and tachycardia, whereas only 1 of 11 sufentanil patients required additional treatment (P less than 0.001). Three of 9 etomidate patients had ST segment changes of new myocardial ischemia following induction and intubation; two other etomidate patients developed Q waves on their postoperative electrocardiograms, indicative of a perioperative myocardial infarction. No sufentanil patient demonstrated either ischemia or infarction. It is concluded that sufentanil-succinylcholine provides more stable hemodynamics and fewer ischemic myocardial events than etomidate-succinylcholine in patients undergoing myocardial revascularization surgery.

Effects of thoracic epidural analgesia with morphine or bupivacaine on lower oesophageal motility--an experimental study in man

Lower oesophageal peristalsis and lower oesophageal sphincter (LOS) pressure during thoracic epidural analgesia (TEA) were studied in 20 healthy volunteers. After oesophageal manometric baseline recordings, 10 volunteers received 4 mg epidural morphine. The other ten received 0.5% bupivacaine epidurally in sufficient amounts to block the sympathetic innervation of the oesophagus. Thereafter oesophageal manometry was repeated. During epidural morphine oesophageal peristalsis, resting LOS pressure and the contraction of LOS after swallowing did not change, but the relaxation of the LOS in response to swallowing decreased significantly (P less than 0.01). Following TEA with bupivacaine, neither distal oesophageal peristalsis nor LOS pressure changed.

Silent regurgitation in day case gynaecological patients

The effect of metoclopramide premedication on the incidence of gastric regurgitation and postoperative nausea and vomiting was studied in 101 women during gynaecological procedures performed under mask anaesthesia. All patients were premedicated orally with carmine red and temazepam. A treatment group of 48 women also received oral metoclopramide. Anaesthesia was standardised in both groups. None of the women regurgitated gastric contents. Pharyngeal pH was measured in the last 68 patients and found to be greater than 5 in all instances. Postoperative nausea and vomiting were significantly less frequent in the treatment group.

Effects of benzodiazepines on laryngeal reflexes. Comparison of lormetazepam and Diazemuls

Of 20 volunteers, five were given intravenous Diazemuls 15 mg over 15 seconds, and three groups of five were given lormetazepam 2 mg intravenously over 10, 20 and 60 seconds, respectively. Laryngeal reactivity and psychomotor function were tested at intervals from prior to injection until 4 hours after injection. For equivalent degrees of depression of psychomotor function, lormetazepam depressed the laryngeal reflex less than Diazemuls (p = 0.004). Lormetazepam give over 60 seconds depressed the laryngeal reflex more than when given over 10 seconds (p = 0.008) or over 20 seconds (p = 0.048), although a significant difference was not demonstrated between the 10-second and 20-second groups. These results concur with experimental evidence that benzodiazepine receptor multiplicity exists, which allows various members of the benzodiazepine group of drugs to exhibit differing therapeutic ratios for their various effects.

Manometric evaluation of the feline esophagus

Fifteen healthy mongrel cats were manometrically evaluated to quantitate esophageal function and to establish the feline esophagus as an appropriate model for investigations relevant to human physiology and pathology. Detailed findings are presented in the paper. Characteristics of the upper and lower esophageal high-pressure zones and of esophageal body motility were found to be similar to human values. Response to bethanechol stimulation was also similar to that seen in humans. This study establishes normal manometric values for the feline esophagus and validates it as an appropriate model for investigations of esophageal physiology and pathophysiology.

Influence of morphine on the distal oesophagus and the lower oesophageal sphincter--a manometric study

Basal pressure and relaxation of the lower oesophageal sphincter (LOS) as well as amplitude, duration and propagation velocity of peristaltic waves in the distal third of oesophagus were measured in 15 healthy adults (nine men and six women). A highly standardised technique was used employing manometric equipment including a low-compliance pneumohydraulic infusion system and a triple lumen recording catheter. After establishment of baseline manometry values the catheter was positioned with its distal orifice in the lower oesophageal sphincter. In 10 subjects 0.2 mg/kg body weight of morphine sulphate was then injected subcutaneously. In five others equal volume of saline was given. The manometric data were analysed blindly. Repeated manometric evaluations were carried out 15, 30, 45, 60, and 75 minutes after the injection. Morphine increased slightly LOS-pressure and significantly (p less than 0.001) decreased LOS-relaxation, the maximal effect occurring 30 minutes after the injection. Amplitude of peristaltic waves increased slightly but insignificantly, whereas propagation velocity and duration were uninfluenced. The results of this study suggest that pharmacologic doses of morphine influence normal function of the LOS and possibly the distal oesophagus. The role of endogenous opiates in this respect, however, awaits further studies. It is suggested that abnormalities in opioid neurotransmission may explain some of the non-specific oesophageal motility disorders.

Time-related effects of benzodiazepines on intestinal motility in conscious dogs

The effects of diazepam and GABA on intestinal motility were investigated in fasted dogs fitted with strain-gauge transducers. Injected intravenously at 9.00 and 16.00 h, diazepam (0.5 mg kg-1) affected intestinal motility only during darkness i.e. from 19.00 to 7.00 h. These jejunal motor effects which were mimicked by GABA, (0.3 mg kg-1 i.v.) corresponded to a disruption of the migrating myoelectric complex (MMC) with an increased contractile activity. These results demonstrate that benzodiazepines affect the intestinal motility in dog and suggest that the effects are related to sleep-stages.