Post-operative pain relief using local infiltration analgesia during open abdominal hysterectomy: a randomized, double-blind study.

BACKGROUND: Post-operative pain is common and often severe after open abdominal hysterectomy, and analgesic consumption high. This study assessed the efficacy of local infiltration analgesia (LIA) injected systematically into different tissues during surgery compared with saline on post-operative pain and analgesia. METHODS: Fifty-nine patients were randomized to Group LIA (n = 29) consisting of 156 ml of a mixture of 0.2% ropivacaine + 30 mg ketorolac + 0.5 mg (5 ml) adrenaline, where the drugs were injected systematically in the operating site, around the proximal vagina, the ligaments, in the fascia and subcutaneously, or to saline and intravenous ketorolac, Group C (Control, n = 28), in a double-blind study. Post-operative pain, analgesic consumption, side-effects, and home discharge were analysed. RESULTS: Median dose of rescue morphine given 0-24 h after surgery was significantly lower in group LIA (18 mg, IQR 5-25 mg) compared with group C (27 mg, IQR 15-43 mg, P = 0.028). Median time to first analgesic injection was significantly longer in group LIA (40 min, IQR 20-60 min) compared with group C (20 min, IQR 12-30 min, P = 0.009). NRS score was lower in the group LIA compared with group C in the direct post-operative period (0-2 h). No differences were found in post-operative side-effects or home discharge between the groups. DISCUSSION: Systematically injected local infiltration analgesia for pain management was superior to saline in the primary endpoint, resulting in significantly lower rescue morphine requirements during 0-24 h, longer time to first analgesic request and lower early post-operative pain intensity.

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.

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.

Effects of different respiratory maneuvers on esophageal sphincters in obese patients before and during anesthesia.

BACKGROUND: Data on esophageal sphincters in obese individuals during anesthesia are sparse. The aim of the present study was to evaluate the effects of different respiratory maneuvers on the pressures in the esophagus and esophageal sphincters before and during anesthesia in obese patients. METHODS: Seventeen patients, aged 28-68 years, with a BMI ≥ 35 kg/m², who were undergoing a laparoscopic gastric by-pass surgery, were studied, and pressures from the hypopharynx to the stomach were recorded using high-resolution solid-state manometry. Before anesthesia, recordings were performed during normal spontaneous breathing, Valsalva and forced inspiration. The effects of anesthesia induction with remifentanil and propofol were evaluated, and positive end-expiratory pressure (PEEP) 10 cmH2O was applied during anesthesia. RESULTS: During spontaneous breathing, the lower esophageal sphincter (LES) pressure was significantly lower during end-expiration compared with end-inspiration (28.5 ± 7.7 vs. 35.4 ± 10.8 mmHg, P<0.01), but barrier pressure (BrP) and intra-gastric pressure (IGP) were unchanged. LES, BrP (P<0.05) and IGP (P<0.01) decreased significantly during anesthesia. BrP remained positive in all patients. IGP increased during Valsalva (P<0.01) but was unaffected by PEEP. Esophageal pressures were positive during both spontaneous breathing and mechanical ventilation. Esophageal pressures increased during PEEP from 9.4 ± 3.8 to 11.3 ± 3.3 mmHg (P<0.01). CONCLUSION: During spontaneous breathing, the LES pressure was the lowest during end-expiration but there were no differences in BrP and IGP. LES, BrP and IGP decreased during anesthesia but BrP remained positive in all patients. During the application of PEEP, esophageal pressures increased and this may have a protective effect against regurgitation.

Body positions and esophageal sphincter pressures in obese patients during anesthesia.

BACKGROUND: The lower esophageal sphincter (LES) and the upper esophageal sphincter (UES) play a central role in preventing regurgitation and aspiration. The aim of the present study was to evaluate the UES, LES and barrier pressures (BP) in obese patients before and during anesthesia in different body positions. METHODS: Using high-resolution solid-state manometry, we studied 17 patients (27-63 years) with a BMI>or=35 kg/m(2) who were undergoing a laparoscopic bariatric surgery before and after anesthesia induction. Before anesthesia, the subjects were placed in the supine position, in the reverse Trendelenburg position (+20 degrees) and in the Trendelenburg position (-20 degrees). Thereafter, anesthesia was induced with remifentanil and propofol and maintained with remifentanil and sevoflurane, and the recordings in the different positions were repeated. RESULTS: Before anesthesia, there were no differences in UES pressure in the different positions but compared with the other positions, it increased during the reverse Trendelenburg during anesthesia. LES pressure decreased in all body positions during anesthesia. The LES pressure increased during the Trendelenburg position before but not during anesthesia. The BP remained positive in all body positions both before and during anesthesia. CONCLUSION: LES pressure increased during the Trendelenburg position before anesthesia. This effect was abolished during anesthesia. LES and BPs decreased during anesthesia but remained positive in all patients regardless of the body position.

Effects of fentanyl on gastric myoelectrical activity: a possible association with polymorphisms of the mu-opioid receptor gene?

BACKGROUND: Opioids have inhibitory effects on gastric motility, but the mechanism is far from clear. Electrical slow waves in the stomach determine the frequency and the peristaltic nature of gastric contractions. The primary aim of this study was to investigate the effects of the opioid fentanyl on gastric myoelectric activity. As there were large variations between the subjects, we investigated whether the variation was correlated to single nucleotide polymorphisms (SNP) of the mu-opioid receptor (MOR) gene. METHODS: We used cutaneous multichannel electrogastrography (EGG) to study myoelectrical activity in 20 patients scheduled for elective surgery. Fasting EGG was recorded for 30 min, followed by intravenous administration of fentanyl 1 microg/kg and subsequent EGG recording for 30 min. Spectral analysis of the two recording periods was performed and the variables assessed were dominant frequency (DF) of the EGG and its power (DP). Genetic analysis of the SNP A118G and G691C of the MOR gene was performed with the polymerase chain reaction technique. RESULTS: There was a significant reduction in DF and DP after intravenous fentanyl. However, there was a large variation between the patients. In eight subjects EGG was unaffected, five subjects had a slower DF (bradygastria) and in six subjects the slow waves disappeared. We found no correlation between the EGG outcome and the presence of A118G or G691C in the MOR gene. CONCLUSIONS: Fentanyl inhibited gastric myoelectrical activity in about half of the subjects. The variation could not be explained by SNP in the MOR gene. Because of small sample size, the results must be regarded as preliminary observations.

Effects of pain stimulation on bispectral index, heart rate and blood pressure at different minimal alveolar concentration values of sevoflurane.

BACKGROUND: The aim of the present study was to examine the level of unconsciousness measured with bispectral index (BIS) at different minimal alveolar concentration (MAC) levels of sevoflurane, and to study the hemodynamic and BIS reactions during noxious stimulation with transcutaneous electrical nerve stimulation (TENS) and an ice water pain test (IWP). METHODS: This study was approved by the Ethics Committee and was performed on 10 healthy, young volunteers (six males and four females), ASA physical status I. Anesthesia was induced and maintained with sevoflurane in an oxygen/air mixture. The volunteers were spontaneously breathing, but if necessary, ventilation was mechanically supported. TENS and IWP were performed at 1.0, 1.5 and 2.0 MAC of sevoflurane. RESULTS: At 1.0 MAC, there was a significant increase in BIS during pain stimulation both with IWP (P<0.03) and with TENS (P<0.005), but at 1.5 MAC there were no changes. A marked variation in BIS was seen at 2.0 MAC, with periods of burst suppression and periods of high BIS values despite clinical signs of deep anesthesia. These marked variations in BIS were seen before, during and after pain stimulation. One volunteer (# 8) had a short episode of convulsions at 2.0 MAC. CONCLUSION: BIS, heart rate and blood pressure increased during pain stimulation at 1.0 MAC but not at 1.5 MAC of sevoflurane. There was a remarkable variation in BIS at 2.0 MAC of sevoflurane, with BIS values indicating wakefulness despite clinical signs of deep anesthesia. This BIS variation is probably caused by epileptogenic activity due to sevoflurane.

The effects on the lower esophageal sphincter of sevoflurane induction and increased intra-abdominal pressure during laparoscopy.

BACKGROUND: Today sevoflurane is one of the most frequently used volatile anesthetics. The speed of induction can approach that of intravenous anesthetics, and case reports using sevoflurane induction for emergency anesthesia have been published. The purpose of this study in laparoscopic cholecystectomy patients was to investigate the effects of sevoflurane during inhalation induction on the lower esophageal sphincter pressure (LESP) and barrier pressure (BrP). The effects on lower esophageal sphincter (LES) and BrP of increased intra-abdominal pressure during laparoscopy were also evaluated. METHODS: We recorded LESP and BrP in nine patients using a Dent sleeve device. Recordings were made before and after inhalation induction of anesthesia with 8% sevoflurane, as well as before and after insufflation of CO(2) into the abdomen. RESULTS: After induction with sevoflurane, LESP (P= 0.039) and BrP (P= 0.020) decreased. Nevertheless, BrP was kept positive in all patients. Insufflation of CO(2) into the abdomen during laparoscopy induced a significant increase in LESP (P= 0.02) and gastric pressure (P= 0.004). However, there was no significant change in BrP (P= 0.66); it increased in four patients and decreased in five. CONCLUSION: BrP was kept positive in all patients after induction of anesthesia. Therefore, we believe that in combination with cricoid pressure, inhalation induction with sevoflurane might be a safe choice. As the adaptive increase in LESP during laparoscopy was not enough to retain a barrier pressure in all patients, it is important to be aware of the risk of regurgitation throughout the anesthesia.

Betamethasone does not prevent nausea and vomiting induced by ipecacuanha.

BACKGROUND: Corticosteroids reduce the incidence of PONV but the mode of action is not known. The purpose of this study was to evaluate if betamethasone has serotonin (5-HT) antagonistic effects. Ipecacuanha is known to release serotonin and therefore it was used to induce nausea and vomiting. The 5-HT3 antagonist ondansetron was used as a control substance. METHODS: In a randomized, double-blind, cross-over, placebo-controlled study 10 healthy male and female volunteers (6 M/4F), mean age 19.5 (18-23) years, mean weight 69.7 (53-84) kg, were studied on three occasions separated by at least 1 week. They were randomly allocated to receive pretreatment with betamethasone 8 mg, ondansetron 8 mg, or normal saline 2 ml as placebo on each occasion, 15 min before oral ingestion of 30 ml of Ipecacuanha syrup. After ingestion of ipecacuanha, vomitings were recorded and the intensity of nausea was estimated with a visual analog scale during 2 h. RESULTS: During the first 2 h after ingestion of ipecacuanha nine of the 10 volunteers vomited both after betamethasone and placebo. No volunteer vomited after ondansetron (P < 0.01 vs. betamethasone and placebo). The max VAS for nausea was significantly higher after betamethasone and placebo compared to ondansetron (P < 0.01). There were no statistically significant differences of the max VAS for nausea between betamethasone and placebo. CONCLUSION: This study in volunteers has shown that betamethasone does not prevent nausea and vomiting induced by oral intake of ipecacuanha syrup. As ipecacuanha releases 5-hydroxytryptamin, it can be concluded that betamethasone does not have 5-HT3 antagonistic effects.

Dexamethasone is as effective as ondansetron for the prevention of postoperative nausea and vomiting following breast surgery.

INTRODUCTION: Postoperative nausea and vomiting remain a common problem following breast surgery. This study assesses whether dexamethasone is as effective as ondansetron in the control of postoperative nausea and vomiting (PONV). METHODS: Eighty ASA I-III patients undergoing breast surgery for carcinoma of the breast were included in the study. Following premedication with diazepam 5-10 mg, patients were induced with fentanyl 50 micro g and propofol 2-2.5 mg kg-1. A larynx mask was inserted and anesthesia maintained with sevoflurane in oxygen and nitrous oxide. Patients were then randomly divided into two groups: Group D (dexamethasone) was given 4 mg dexamethasone i.v. after induction and Group O (ondansetron) was given 4 mg ondansetron at the same time point. Postoperatively, nausea, vomiting and pain were recorded at 1-h intervals during 4 h, and thereafter every 4 h during 24 h. RESULTS: The incidence of PONV during 24 h was 37% and 33% in Group D and Group O, respectively (NS). No differences were found between the groups in the incidence of postoperative nausea, vomiting or pain at the different time intervals. No differences were found in the incidence of PONV in smokers vs. non-smokers. No side-effects of these drugs were observed. CONCLUSIONS: Ondansetron 4 mg or dexamethasone 4 mg are equally effective in the prevention of postoperative nausea and vomiting following breast surgery. Other factors being similar, the difference in cost between these drugs would favor the use of dexamethasone instead of ondansetron when monotherapy against PONV is used.

Clonidine combined with small-dose bupivacaine during spinal anesthesia for inguinal herniorrhaphy: a randomized double-blinded study.

UNLABELLED: The aim of this randomized double-blinded study was to see whether the addition of small-dose clonidine to small-dose bupivacaine for spinal anesthesia prolonged the duration of postoperative analgesia and also provided a sufficient block duration that would be adequate for inguinal herniorrhaphy. We randomized 45 patients to 3 groups receiving intrathecal hyperbaric bupivacaine 6 mg combined with saline (Group B), clonidine 15 micro g (Group BC15), or clonidine 30 micro g (Group BC30); all solutions were diluted with saline to 3 mL. The sensory block level was insufficient for surgery in five patients in Group B, and these patients were given general anesthesia. Patients in Groups BC15 and BC30 had a significantly higher spread of analgesia (two to four dermatomes) than those in Group B. Two-segment regression, return of S1 sensation, and regression of motor block were significantly longer in Group BC30 than in Group B. The addition of clonidine 15 and 30 micro g to bupivacaine prolonged time to first analgesic request and decreased postoperative pain with minimal risk of hypotension. We conclude that clonidine 15 micro g with bupivacaine 6 mg produced an effective spinal anesthesia and recommend this dose for inguinal herniorrhaphy, because it did not prolong the motor block. IMPLICATIONS: The addition of clonidine 15 micro g to 6 mg of hyperbaric bupivacaine increases the spread of analgesia, prolongs the time to first analgesic request, and decreases postoperative pain, compared with bupivacaine alone, during inguinal herniorrhaphy under spinal anesthesia.

Low-dose bupivacaine plus fentanyl for spinal anesthesia during ambulatory inguinal herniorrhaphy: a comparison between 6 mg and 7. 5 mg of bupivacaine.

BACKGROUND: Inguinal herniorrhaphy is commonly performed as an outpatient procedure. Spinal anesthesia offers some advantages over general anesthesia in this setting. METHODS: Forty patients were randomly divided into two groups according to a double-blind protocol: Group L had spinal anesthesia with bupivacaine 6.0 mg and Group H with bupivacaine 7.5 mg; in both groups, fentanyl 25 micro g was added to the spinal anesthetic. The sensory block was measured by 'pin-prick' and the motor block was evaluated by a modified Bromage scale. RESULTS: No differences were seen in the spread, duration and regression of sensory block between the groups on the operated side. A greater number of patients required analgesics during the operation in Group L (6) compared with Group H (1) (P<0.05). The return of the modified Bromage scale to grade 0 was earlier in Group L than in Group H (P<0.05) but the time to mobilization and discharge was similar. Seven patients (17%) needed to be catheterized and two had the catheter retained overnight. Times to home discharge (median) were 350 and 445 min, respectively, in Groups L and H. Postoperatively and during the first week, visual analog pain scores, analgesic requirements and side-effects were similar between the groups. In Group H, 95% of the patients and in Group L 85% would have the same anesthetic again if operated upon for a similar procedure. CONCLUSIONS: Spinal anesthesia with bupivacaine 7.5 mg and fentanyl offers an alternative to general or local anesthesia for ambulatory inguinal herniorrhaphy. However, the long discharge times and risk for urinary retention restrict its routine use in all patients.

Perioperative gastric emptying is not a predictor of early postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

UNLABELLED: It is not known whether patients with postoperative nausea and vomiting (PONV) have delayed gastric emptying compared with patients without PONV. We compared the perioperative rate of gastric emptying in patients experiencing PONV with the rate in those without PONV immediately after laparoscopic cholecystectomy. Gastric emptying was studied by the acetaminophen method. Acetaminophen is not absorbed from the stomach but is rapidly absorbed from the small intestine, and the rate of gastric emptying therefore determines the rate of absorption of acetaminophen administered into the stomach. Forty patients (ASA physical status I and II) were included in the study. After the induction of anesthesia, a gastric tube was positioned in the stomach and 1.5 g of acetaminophen dissolved in 200 mL of water was administered. Venous blood samples for the determination of serum acetaminophen concentrations were taken before and at 15-min intervals during a period of 180 min after the administration of acetaminophen. Twenty-six patients experienced nausea during the first 4 h postoperatively. The other 14 patients had no nausea. There were no statistically significant differences in the maximal acetaminophen concentration, the time taken to reach the maximal concentration, or the area under the serum acetaminophen concentration time curves from 0 to 60, 0-120, and 0-180 min between the groups of patients with or without PONV. We did not find any relationship between postoperative gastric emptying and PONV, and therefore gastric emptying is not a predictor of PONV. IMPLICATIONS: The incidence of postoperative nausea and vomiting is frequent after laparoscopic cholecystectomy. This study has shown that perioperative gastric emptying is not a predictor of early postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy.

Effects of clonidine and dopamine on gastric tone.

BACKGROUND AND OBJECTIVE: The effects of clonidine and dopamine, both alone and together, on gastric tone were studied using an electronic barostat. This enabled volume changes to be measured in an intragastric bag with a constant preset pressure. METHODS: Nine healthy male volunteers were each studied on two occasions in a randomized order. During each study period, a continuous infusion of dopamine was given, starting with a dose of 2.5 microg kg(-1) min(-1), and then increasing at 15-min intervals to 5.0 and 7.5 microg kg(-1) min(-1). Clonidine 150 microg intravenously was given on one occasion during the infusion of dopamine (7.5 microgkg(-1) min(-1)) and on the other occasion 15 min before the dopamine infusion started. RESULTS: During dopamine infusion, the intragastric bag volume increased (gastric tone therefore decreasing) in a dose-related manner (total increase 290 +/- 114 mL). Clonidine given either during or before dopamine infusion did not influence the bag volume. When the dopamine infusion started 15 min after clonidine, the bag volume did not change until the infusion of dopamine reached 7.5 microg kg(-1) min(-1) (total increase 205 +/- 156 mL). CONCLUSIONS: Dopamine reduced gastric tone in a dose-related manner, and clonidine did not influence gastric tone per se. If clonidine is given before dopamine, the effects of dopamine are reduced.

Superior prolonged antiemetic prophylaxis with a four-drug multimodal regimen - comparison with propofol or placebo.

BACKGROUND: The purpose of this study was to compare the effects of a low-dose propofol infusion with a four-drug multimodal regimen for prophylaxis of postoperative nausea and vomiting (PONV). METHODS: : PONV was studied in two patient groups with a known high incidence. Through a stratified randomization, 60 patients undergoing breast surgery and 120 patients undergoing abdominal surgery were randomized to three groups of equal size: the propofol group (P), the multidrug group (M) and the control group (C). All patients received general anesthesia, induction with propofol and maintenance with sevoflurane. After induction, patients in the P group received a continuous infusion of propofol 1 mg/kg/h during the operation and the first 4 postoperative h. Patients in the M group received dexamethasone 4 mg and three antiemetics, ondansetron 4 mg, droperidol 1.25 mg and metoclopramide 10 mg i.v. In the control group no prophylaxis was given. Nausea and pain were evaluated by incidence and a visual analog scale (0-10 cm). All emetic episodes were noted by the staff during the first 4 h and by the patients during the next 20 h. RESULTS: The overall incidence of PONV during the first 24 h postoperatively was significantly lower in the M group (24%) than in the P group (49%) (P<0.01) or the C group (70%) (P<0.001). The incidence of PONV increased significantly both in patients undergoing breast surgery and abdominal surgery after termination of propofol. The number of patients who vomited was significantly lower in the M group, both in breast surgery patients (5%) and abdominal surgery patients (3%) compared to patients in the propofol groups (breast 16% NS; abdominal 29%, P<0.05) and in the control groups (breast 37%, P<0.01; abdominal 29%, P<0.01). CONCLUSION: The incidence of PONV is very high in patients undergoing breast and abdominal surgery. In the present study antiemetic prophylaxis with a combination of droperidol, ondansetron, metoclopramide and dexamethasone was more effective in preventing PONV, especially vomiting, than a postoperative low-dose infusion of propofol, which had a short lasting effect.

Propofol and gastric effects of morphine.

OBJECTIVE: The purpose of this study was to evaluate whether propofol abolishes morphine-induced effects on gastric emptying and gastric tone. METHOD: The study was carried out before anesthesia in 40 patients (ASA I-II). Gastric tone was measured in 20 patients by an electronic barostat. Volume changes were thereby registered continuously in an intragastric flaccid bag with a constant preset pressure. All patients received i.v. morphine 0.1 mg x kg(-1) before the measurements and, in a randomized order, 10 of the patients also received a bolus dose of propofol 1 mg. kg-1 before morphine. Gastric emptying was studied with the paracetamol method in 20 patients. All patients received morphine 0.1 mg x kg(-1) i.v. 10 min before oral ingestion of 1.5 g paracetamol in 200 ml water and, in a randomized order, 10 of the patients also received propofol, a bolus dose of 0.3 mg x kg(-1) before morphine, followed by an infusion of 1 mg x kg(-1) x h(-1) during the whole study (2 h). RESULTS: The volume in the intragastric bag increased in all patients receiving morphine without propofol. In the group that received propofol before morphine, the volume in the intragastric bag decreased in all patients. The volume differences between the groups were statistically significant (P<0.01). There were no statistically significant differences of the AUC60, Cmax and Tmax of serum paracetamol concentrations between the morphine and propofol-morphine groups. CONCLUSION: Propofol did not abolish morphine-induced delay of gastric emptying even if propofol abolished the decrease of gastric tone induced by morphine.

Dopamine reduces gastric tone in a dose-related manner.

BACKGROUND: Dopamine may have effects on gastrointestinal motility. The aim of this study was, therefore, to determine whether dopamine reduces gastric tone and whether the effects of dopamine can be blocked by a dopamine antagonist. METHODS: Eight healthy male volunteers were studied on two occasions in a randomized order. A continuous infusion of incremental doses of dopamine (2.5, 5.0, 7.5 microg kg(-1) min(-1)) was given on both occasions. Ten milligrams of the dopamine-antagonist metoclopramid was given before the dopamine infusion on one occasion and during the dopamine infusion (7.5 microg kg(-1) min(-1)) on the other occasion. The gastric tone was measured by an electronic barostat, an instrument with an electronic control system that maintains a constant preset pressure within an air-filled, flaccid intragastric bag by means of momentary changes in the intragastric volume of air. Volume and pressure in the gastric bag were continuously recorded by the electronic barostat and sampled in a computer. RESULTS: Dopamine induced a dose-related increase in the intragastric bag volume. Metoclopramid given as a 10 mg i.v. bolus dose during the infusion of dopamine significantly decreased the intragastric bag volume, but 10 mg of metoclopramid i.v. before the dopamine infusion did not influence the bag volume per se. CONCLUSION: Dopamine decreases gastric tone in a dose-related manner and 10 mg of the dopamine-antagonist metoclopramid is not enough to fully reverse these effects.

Dopamine delays gastric emptying and prolongs orocaecal transit time in volunteers.

Dopamine decreases gastric tone and may therefore influence gastrointestinal motility. The aim of this investigation was to study the effects of a continuous infusion of dopamine on gastric emptying and orocaecal transit time. Nine healthy male volunteers were studied on two occasions in a randomized order. All volunteers received on separate days a continuous infusion of dopamine 5 micrograms kg-1 min-1 on one occasion and normal saline on the other occasion. Gastric emptying was measured by the paracetamol absorption test and orocaecal transit time by the hydrogen breath test. During the dopamine infusion the area under the paracetamol concentration curve was significantly smaller than during control conditions (P = 0.02). Orocaecal transit time was prolonged during the dopamine infusion (P = 0.02). Dopamine delays gastric emptying and prolongs orocaecal transit time.

Effects of adenosine infusion on gastric emptying in healthy volunteers.

BACKGROUND: A low dose of systemic adenosine infusion has been shown to induce antinociception in clinical experimental studies as well as in patients. There is no clinical information about the effect of adenosine on the motility of the gastrointestinal tract. The aim of this study was therefore to evaluate the effect of exogenous adenosine administration on gastric emptying in man. METHOD: Ten healthy male volunteers (22-45 yrs) were included in a placebo-controlled, double-blind, randomised, cross-over study, where the experiments were separated by at least one week. During one session the volunteers received a continuous intravenous infusion of adenosine (50 micrograms.kg-1.min-1) initiated 15 min prior to the test of gastric emptying (a standard test meal, followed by oral acetaminophen, 2 g) and lasting throughout the experiment (2 h). During the other experimental session an infusion of saline was given. Acetaminophen absorption test was used as an indirect measure of the rate of gastric emptying. Venous acetaminophen concentration curves were produced and the maximum acetaminophen concentration (Cmax), the time to reach the maximum concentration (Tmax), and the area under the serum acetaminophen concentration time curve from 0 to 60 min (AUC60) were calculated. RESULTS: There was no difference between placebo and adenosine in Cmax (197 vs. 199 mumol.L-1, P = 0.80), Tmax (23 vs. 45 min, P = 0.14), AUC60 (9633 vs. 9111 min.mumol.L-1, P = 0.28). CONCLUSION: The results demonstrate that adenosine in a clinically antinociceptive dose of 50 micrograms.kg-1.min-1 does not affect the rate of gastric emptying in healthy volunteers.

Effects of propofol on ipecacuanha-induced nausea and vomiting.

BACKGROUND: The purpose of this study was to evaluate if propofol has 5-HT3 antagonistic effects. Ipecacuanha is known to release serotonin (5-HT) in the gastrointestinal tract and therefore ipecacuanha syrup was used to induce nausea and vomiting. The 5-HT3 antagonist ondansetron was used as a control substance. METHOD: Ten healthy male volunteers (20-37 years) were studied on three occasions and were randomly allocated to receive a concomitant infusion of propofol (initial bolus 0.1 mg kg(-1) then 1 mg kg(-1)h(-1)), ondansetron (initial bolus 0.11 mg kg(-1) then 14 microg kg(-1)h(-1)) and placebo on either occasion. The infusions started 30 min before oral ingestion of 30 ml of ipecacuanha and continued until 150 min after the intake. The number of retchings was recorded and the intensity of nausea was estimated by the subjects on a visual analog scale. RESULTS: During the first 150 min after ingestion of ipecacuanha there were no retchings during the ondansetron infusion (P=0.01 vs placebo, P=0.02 vs propofol) and significantly fewer retchings during propofol infusion compared to placebo (P<0.02). There was no nausea during the ondansetron infusion (P<0.01 vs placebo and propofol) but the volunteers experienced nausea both during the placebo and propofol infusion (NS). CONCLUSION: This study in volunteers has shown that propofol reduces the intensity of retching after oral intake of ipecacuanha syrup. As ipecacuanha releases 5-hydroxytryptamine, it can be concluded that propofol may have a weak 5-HT3 antagonistic effect.