Postoperative recovery in preschool-aged children: A secondary analysis of a randomized controlled trial comparing premedication with midazolam, clonidine, and dexmedetomidine.

BACKGROUND: Preoperative anxiety in pediatric patients can worsen postoperative outcomes and delay discharge. Drugs aimed at reducing preoperative anxiety and facilitating postoperative recovery are available; however, their effects on postoperative recovery from propofol-remifentanil anesthesia have not been studied in preschool-aged children. Thus, we aimed to investigate the effects of three sedative premedications on postoperative recovery from total intravenous anesthesia in children aged 2-6 years. METHODS: In this prespecified secondary analysis of a double-blinded randomized trial, 90 children scheduled for ear, nose, and throat surgery were randomized (1:1:1) to receive sedative premedication: oral midazolam 0.5 mg/kg, oral clonidine 4 µg/kg, or intranasal dexmedetomidine 2 µg/kg. Using validated instruments, outcome measures including time for readiness to discharge from the postoperative care unit, postoperative sedation, emergence delirium, anxiety, pain, and nausea/vomiting were measured. RESULTS: After excluding eight children due to drug refusal or deviation from the protocol, 82 children were included in this study. No differences were found between the groups in terms of median time [interquartile range] to readiness for discharge (midazolam, 90 min [48]; clonidine, 80 min [46]; dexmedetomidine 100.5 min [42]). Compared to the midazolam group, logistic regression with a mixed model and repeated measures approach found no differences in sedation, less emergence delirium, and less pain in the dexmedetomidine group, and less anxiety in both clonidine and dexmedetomidine groups. CONCLUSIONS: No statistical difference was observed in the postoperative recovery times between the premedication regimens. Compared with midazolam, dexmedetomidine was favorable in reducing both emergence delirium and pain in the postoperative care unit, and both clonidine and dexmedetomidine reduced anxiety in the postoperative care unit. Our results indicated that premedication with α2 -agonists had a better recovery profile than short-acting benzodiazepines; although the overall recovery time in the postoperative care unit was not affected.

Palonosetron as prophylaxis for post-discharge nausea and vomiting: a prospective, randomised, double-blind, placebo-controlled trial in ambulatory surgery.

BACKGROUND: Approximately 25% of ambulatory surgery patients experience post-discharge nausea and vomiting (PDNV). We aimed to investigate whether palonosetron, a long-acting anti-emetic, decreases the incidence of PDNV in high-risk patients. METHODS: In this prospective, randomised, double-blind, placebo-controlled trial, 170 male and female patients undergoing ambulatory surgery under general anaesthesia, with a high predicted risk for PDNV, were randomised to receive either palonosetron 75 µg i.v. (n=84) or normal saline (n=86) before discharge. During the first 3 postoperative days (PODs), we measured outcomes using a patient questionnaire. The primary outcome was the incidence of a complete response (no nausea, vomiting, or use of rescue medication) until POD 2. Secondary outcomes included the incidence of PDNV each day until POD 3. RESULTS: The incidence of a complete response until POD 2 was 48% (n=32) in the palonosetron group and 36% (n=25) in the placebo group (odds ratio 1.69 [95% confidence interval: 0.85-3.37]; P=0.131). No significant difference in the incidence of PDNV was observed between the two groups on the day of surgery (47% vs 56%; P=0.31). Significant differences in the incidence of PDNV were found on POD 1 (18% vs 34%; P=0.033) and POD 2 (9% vs 27%; P=0.007). No differences were observed on POD 3 (15% vs 13%; P=0.700). CONCLUSIONS: Compared with placebo, palonosetron did not reduce the overall incidence of post-discharge nausea and vomiting up to postoperative day 2. The lower incidence of post-discharge nausea and vomiting on poatoperative days 1 and 2 in the palonosetron group requires further investigation. CLINICAL TRIAL REGISTRATION: EudraCT 2015-003956-32.

Cardiorespiratory Response to Sedative Premedication in Preschool Children: A Randomized Controlled Trial Comparing Midazolam, Clonidine, and Dexmedetomidine.

PURPOSE: Sedative premedication in children may negatively impact their cardiorespiratory status during the perioperative course, and no clear consensus exists on the optimal premedication treatment for pediatric patients. The objective was to compare the perioperative cardiorespiratory responses to sedation using three different sedative premedication regimens in preschool children scheduled for surgery with total intravenous anesthesia. DESIGN: A single-center randomized controlled trial. METHODS: This is a planned secondary analysis of a study conducted at a 200-bed tertiary referral hospital. Ninety children participated in the study. They were aged 2-6 years and scheduled for ear, nose, and throat surgery with propofol/remifentanil anesthesia. Participants were randomly assigned to receive oral midazolam 0.5 mg/kg-1 (MID), oral clonidine 4 mcg/kg-1 (CLO), or intranasal dexmedetomidine 2 mcg/kg-1 (DEX). The main outcome measures were the sedation level, based on the Ramsay Sedation Scale (RSS), and cardiorespiratory status, monitored during the perioperative period. FINDINGS: The final cohort had 83 children (MID, n=27; CLO, n=26; DEX, n=30), with similar intergroup patient characteristics. RSS scores were lower in the MID group than in the CLO and DEX groups before induction and within 30 min postsurgery (P<0.001 and P=0.006, respectively). A negative correlation existed between the RSS and heart rate (HR) (r=-0.570, P<0.001). Before anesthesia induction, the respiratory rate was lowest in the DEX group (MID 21.5±1.7 min-1, CLO 20.6±2.6 min-1, DEX 20.2±1.7 min-1; P=0.042). The HR was lower in the CLO and DEX groups than in the MID group (MID, 102.8±10.0 min-1; CLO, 87.4±9.6 min-1; DEX, 87.6±7.9 min-1; P<0.001). The HR was lower immediately after induction (P=0.009) and intraoperatively (P=0.025) in the CLO and DEX groups than in the MID group. CONCLUSIONS: When used as premedication before propofol/remifentanil anesthesia, clonidine and dexmedetomidine provided deeper preoperative sedation compared to midazolam. From a clinical perspective, all three study drugs provided essentially stable cardiovascular and respiratory conditions during the entire perioperative period.

Pre-operative point-of-care assessment of left ventricular diastolic dysfunction, an observational study.

BACKGROUND: Left ventricular (LV) diastolic dysfunction is an acknowledged peri-operative risk factor that should be identified before surgery. This study aimed to evaluate a simplified echocardiographic method using e' and E/e' for identification and grading of diastolic dysfunction pre-operatively. METHODS: Ninety six ambulatory surgical patients were consecutively included to this prospective observational study. Pre-operative transthoracic echocardiography was conducted prior to surgery, and diagnosis of LV diastolic dysfunction was established by comprehensive and simplified assessment, and the results were compared. The accuracy of e'-velocities in order to discriminate patients with diastolic dysfunction was established by calculating accuracy, efficiency, positive (PPV) and negative predictive (NPV) values, and area under the receiver operating characteristic curve (AUROC). RESULTS: Comprehensive assessment established diastolic dysfunction in 77% (74/96) of patients. Of these, 22/74 was categorized as mild dysfunction, 43/74 as moderate dysfunction and 9/74 as severe dysfunction. Using the simplified method with e' and E/e', diastolic dysfunction was established in 70.8% (68/96) of patients. Of these, 8/68 was categorized as mild dysfunction, 36/68 as moderate dysfunction and 24/68 as severe dysfunction. To discriminate diastolic dysfunction of any grade, e'-velocities (mean < 9 cm s- 1) had an AUROC of 0.901 (95%CI 0.840-0.962), with a PPV of 55.2%, a NPV of 90.9% and a test efficiency of 0.78. CONCLUSIONS: The results of this study indicate that a simplified approach with tissue Doppler e'-velocities may be used to rule out patients with diastolic dysfunction pre-operatively, but together with E/e' ratio the severity of diastolic dysfunction may be overestimated. TRIAL REGISTRATION: Clinicaltrials.gov, Identifier: NCT03349593 . Date of registration 21/11/2017. https://clinicaltrials.gov .

Preoperative anxiety in preschool children: A randomized clinical trial comparing midazolam, clonidine, and dexmedetomidine.

INTRODUCTION: Anxiety in pediatric patients may challenge perioperative anesthesiology management and worsen postoperative outcomes. Sedative drugs aimed to reducing anxiety are available with different pharmacologic profiles, and there is no consensus on their effect or the best option for preschool children. In this study, we aimed to compare the effect of three different premedications on anxiety before anesthesia induction in preschool children aged 2-6 years scheduled for elective surgery. The secondary outcomes comprised distress during peripheral catheter (PVC) insertion, compliance at anesthesia induction, and level of sedation. PATIENTS AND METHODS: In this double-blinded randomized clinical trial, we enrolled 90 participants aged 2-6 years, who were scheduled for elective ear-, nose-and-throat surgery. The participants were randomly assigned to three groups: those who were administered 0.5 mg/kg oral midazolam, 4 µg/kg oral clonidine, or 2 µg/kg intranasal dexmedetomidine. Anxiety, distress during PVC insertion, compliance with mask during preoxygenation, and sedation were measured using the modified Yale Preoperative Anxiety Scale, Behavioral Distress Scale, Induction Compliance Checklist, and Ramsay Sedation Scale, respectively. RESULTS: Six children who refused premedication were excluded, leaving 84 enrolled patients. At baseline, all groups had similar levels of preoperative anxiety and distress. During anesthesia preparation, anxiety was increased in the children who received clonidine and dexmedetomidine; however, it remained unaltered in the midazolam group. There were no differences in distress during PVC insertion or compliance at induction between the groups. The children in the clonidine and dexmedetomidine groups developed higher levels of sedation than those in the midazolam group. CONCLUSIONS: In preschool children, midazolam resulted in a more effective anxiolysis and less sedation compared to clonidine and dexmedetomidine.

Early post-operative nausea and vomiting: A retrospective observational study of 2030 patients.

BACKGROUND: The overall risk of post-operative nausea and vomiting (PONV) after general anaesthesia is reportedly 20%-40%. The first episode of PONV may occur early in the post-anaesthesia care unit (PACU) or later at the ward or after discharge at home in an ambulatory setting. This study aimed to investigate and describe the risk of early PONV in a PACU, and we hypothesised that patients and perioperative factors were associated with early PONV. METHODS: This single-centre retrospective observational study was conducted in a Swedish county hospital from January to June 2017 and included adult patients who underwent surgical procedures under general anaesthesia. Perioperative data were obtained by reviewing the local registry for surgical procedures, medical records and anaesthesia and post-operative charts. Early PONV was defined as PONV occurring up to 4 hours post-operatively at the PACU. Any notification in the medical records, perioperative charts or the registry regarding nausea, vomiting or PONV treatment was regarded as PONV. Univariate and multivariate analyses were performed for factors associated with early PONV. RESULTS: A total of 2030 patients were included in the study, of which 9.6% (n = 194) experienced early PONV. Factors associated with a high risk of early PONV were suboptimal PONV prophylaxis, need for opioids, female sex, body mass index >35 kg m-2 and major surgery and anaesthesia time ≥60 minutes. CONCLUSION: We found that every 10th patient under general anaesthesia experienced early PONV. Suboptimal PONV prophylaxis and previously acknowledged risk factors for PONV were associated with early PONV.

Preoperative Point-of-Care Assessment of Left Ventricular Systolic Dysfunction With Transthoracic Echocardiography.

BACKGROUND: Left ventricular (LV) systolic dysfunction is an acknowledged perioperative risk factor and should be identified before surgery. Conventional echocardiographic assessment of LV ejection fraction (LVEF) obtained by biplane LV volumes is the gold standard to detect LV systolic dysfunction. However, this modality needs extensive training and is time consuming. Hence, a feasible point-of-care screening method for this purpose is warranted. The aim of this study was to evaluate 3 point-of-care echocardiographic methods for identification of LV systolic dysfunction in comparison with biplane LVEF. METHODS: One hundred elective surgical patients, with a mean age of 63 ± 12 years and body mass index of 27 ± 4 kg/m2, were consecutively enrolled in this prospective observational study. Transthoracic echocardiography was conducted 1-2 hours before surgery. LVEF was obtained by automatic two-dimensional (2D) biplane ejection fraction (EF) software. We evaluated if Tissue Doppler Imaging peak systolic myocardial velocities (TDISm), anatomic M-mode E-point septal separation (EPSS), and conventional M-mode mitral annular plane systolic excursion (MAPSE) could discriminate LV systolic dysfunction (LVEF <50%) by calculating accuracy, efficiency, correlation, positive (PPV) respective negative predictive (NPV) values, and area under the receiver operating characteristic curve (AUROC) for each point-of-care method. RESULTS: LVEF<50% was identified in 22% (21 of 94) of patients. To discriminate an LVEF <50%, AUROC for TDISm (mean <8 cm/s) was 0.73 (95% confidence interval [CI], 0.62-0.84; P < .001), with a PPV of 47% and an NPV of 90%. EPSS with a cutoff value of >6 mm had an AUROC 0.89 (95% CI, 0.80-0.98; P < .001), with a PPV of 67% and an NPV of 96%. MAPSE (mean <12 mm) had an AUROC 0.80 (95% CI, 0.70-0.90; P < 0.001) with a PPV of 57% and an NPV of 98%. CONCLUSIONS: All 3 point-of-care methods performed reasonably well to discriminate patients with LVEF <50%. The clinician may choose the most suitable method according to praxis and observer experience.

Risk of postoperative nausea and vomiting in hip and knee arthroplasty: a prospective cohort study after spinal anaesthesia including intrathecal morphine.

BACKGROUND: The overall risk of postoperative nausea and vomiting after general anaesthesia is approximately 30% even with prophylactic medications. Studies exploring the risk after regional anaesthesia including intrathecal morphine are limited but indicate that intrathecal morphine is highly emetogenic and is additive to the PONV risk associated with other forms of anaesthesia. The aim of this observational study was to investigate the risk of PONV after spinal blockade combined with intrathecal morphine and to explore associations with patient and perioperative factors, including given PONV-prophylaxis. We hypothesized that a large number of patients in a clinical setting receive less prophylaxis than the recommendations in guidelines (suboptimal prophylaxis), leading to a higher risk for PONV compared to those receiving adequate PONV prophylaxis. METHODS: The study was conducted as a prospective observational cohort study regarding PONV in patients undergoing hip/knee replacement under spinal anaesthesia including intrathecal morphine. Patients were included at a county hospital in Sweden during April-November 2013 (n = 59) and September 2014-June 2015 (n = 40). One hundred eight patients entered the study with 99 patients analysed in the final cohort. Patients were followed the first three postoperative days with a questionnaire regarding PONV and peri- and postoperative data was collected. PONV risk is presented as the proportion of patients (%) with PONV and was related to the level of perioperative PONV-prophylaxis (suboptimal/optimal). Univariate analysis was used to analyse factors associated with PONV. RESULTS: Forty-six patients (46%) experienced PONV during the 3-day study period whereof 36 patients (36%) until noon the first day after the procedure. 19/27 patients (70%) that received suboptimal PONV-prophylaxis experienced PONV compared to 27/72 (38%) that received optimal PONV-prophylaxis (p = 0.015). Further, female gender and/or a history of motion sickness were associated with an increased PONV-risk. CONCLUSIONS: There was a high risk for PONV after spinal anaesthesia including morphine. PONV risk was associated with the level of prophylaxis and with known risk factors for PONV. Our findings suggest that a more liberal use of PONV prophylaxis might be motivated.

Survival after primary breast cancer surgery following propofol or sevoflurane general anesthesia-A retrospective, multicenter, database analysis of 6305 Swedish patients.

BACKGROUND: Retrospective studies indicate that the choice of anesthetic can affect long-term cancer survival. Propofol seems to have an advantage over sevoflurane. However, this is questioned for breast cancer. We gathered a large cohort of breast cancer surgery patients from seven Swedish hospitals and hypothesized that general anesthesia with propofol would be superior to sevoflurane anesthesia regarding long-term breast cancer survival. METHODS: We identified all patients who were anaesthetized for breast cancer surgery between 2006 and 2012. The patients were matched to the Swedish Breast Cancer Quality Register, to retrieve tumor characteristics, prognostic factors, and adjuvant treatment as well as date of death. Overall survival between patients undergoing sevoflurane and propofol anesthesia was analyzed with different statistical approaches: (a) multiple Cox regression models adjusted for demographic, oncological, and multiple control variables, (b) propensity score matching on the same variables, but also including the participating centers as a cofactor in a separate analysis. RESULTS: The database analysis identified 6305 patients. The 5-year survival rates were 91.0% and 81.8% for the propofol and sevoflurane group, respectively, in the final model (P = .126). Depending on the statistical adjustment method used, different results were obtained, from a non-significant to a "proposed" and even a "determined" difference in survival that favored propofol, with a maximum of 9.2 percentage points higher survival rate at 5 years (hazard ratio 1.46, 95% CI 1.10-1.95). CONCLUSIONS: It seems that propofol may have a survival advantage compared with sevoflurane among breast cancer patients, but the inherent weaknesses of retrospective analyses were made apparent.

Renal clearance of heparin-binding protein and elimination during renal replacement therapy: Studies in ICU patients and healthy volunteers.

BACKGROUND: Heparin-binding protein (HBP) is released by neutrophils upon activation, and elevated plasma levels are seen in inflammatory states like sepsis, shock, cardiac arrest, and burns. However, little is known about the elimination of HBP. We wanted to study renal clearance of HBP in healthy individuals and in burn patients in intensive care units (ICUs). We also wished to examine the levels of HBP in the effluent of renal replacement circuits in ICU patients undergoing continuous renal replacement therapy (CRRT). METHODS: We measured plasma and urine levels of HBP and urine flow rate in 8 healthy individuals and 20 patients in a burn ICU. In 32 patients on CRRT, we measured levels of HBP in plasma and in the effluent of the CRRT circuit. RESULTS: Renal clearance of HBP (median (IQR) ml/min) was 0.19 (0.08-0.33) in healthy individuals and 0.30 (0.01-1.04) in burn ICU patients. In ICU patients with cystatin C levels exceeding 1.44 mg/l, clearance was 0.45 (0.15-2.81), and in patients with cystatin C below 1.44 mg/l clearance was lower 0.28 (0.14-0.55) (p = 0.04). Starting CRRT did not significantly alter plasma levels of HBP (p = 0.14), and the median HBP level in the effluent on CRRT was 9.1 ng/ml (IQR 7.8-14.4 ng/ml). CONCLUSION: In healthy individuals and critically ill burn patients, renal clearance of HBP is low. It is increased when renal function is impaired. Starting CRRT in critically ill patients does not alter plasma levels of HBP significantly, but HBP can be found in the effluent. It seems unlikely that impaired kidney function needs to be considered when interpreting concentrations of HBP in previous studies. Starting CRRT does not appear to be an effective way of reducing HBP concentrations.

Validation of a prediction model for post-discharge nausea and vomiting after general anaesthesia in a cohort of Swedish ambulatory surgery patients.

BACKGROUND: In ambulatory surgery, post-discharge nausea and vomiting (PDNV) has been identified as a significant problem occurring in more than one-third of patients. OBJECTIVE: To validate a simplified PDNV score in a Swedish population. DESIGN: Prospective observational study. SETTING: Two county hospitals in Sweden: Sundsvall from June 2012 to May 2013 and Sunderbyn from January to October 2014. PATIENTS: Adult patients undergoing ambulatory surgery under general anaesthesia. MAIN OUTCOME MEASURES: Postoperative outcomes with a focus on nausea and vomiting were collected at 2, 4, and 6 h after surgery and on the first three postoperative days. The simplified PDNV score, calculated before discharge, included the factors: female sex, age less than 50 years, history of postoperative nausea and vomiting, postoperative nausea and opioids given postoperatively. The prediction performance of the simplified PDNV score was evaluated in terms of discrimination (area under receiver-operating characteristics curve) and calibration plots and was compared with that of the original development study. RESULTS: A total of 559 patients were asked to participate, of which 431 were included in the final study cohort. The overall risk of postoperative nausea and vomiting and PDNV were 18.8 [95% confidence interval (CI), 15.4-22.8]% and 28.1 (95% CI, 24.0-32.5)%, respectively. The discrimination capacity of the simplified PDNV score in our study was similar to that of the original dataset [area under the curve 0.693 (95% CI, 0.638-0.748) vs. 0.706 (0.681-0.731), absolute difference 0.013]. The slope of the calibration curve was 0.893, with a constant of 0.021 (R-square 0.884). CONCLUSION: In a Swedish cohort of patients, the simplified PDNV score performs well in discriminating between patients who will experience post-discharge nausea and/or vomiting after ambulatory surgery. Our results indicate that the simplified PDNV score is as valid in other cohorts as it was in the original development cohort.

Effects of remifentanil on gastric tone.

OBJECTIVES: Opioids are well known for impairing gastric motility. The mechanism is far from clear and there is wide interindividual variability. The purpose of this study was to evaluate the effect of remifentanil on proximal gastric tone. MATERIALS AND METHODS: Healthy volunteers were studied on two occasions and proximal gastric tone was measured by a gastric barostat. On the first occasion (n=8), glucagon 1 mg IV was given as a reference for a maximal relaxation of the stomach. On the second occasion (n=9), remifentanil was given in incremental doses (0.1, 0.2 and 0.3 microg/kg/min) for 15 min each, followed by a washout period of 30 min. Thereafter, remifentanil was readministered, and 10 min later glucagon 1 mg was given. Mean intragastric bag volumes were calculated for each 5-min interval. RESULTS: Glucagon decreased gastric tone in all subjects. Remifentanil had a marked effect on gastric tone; we found two distinct patterns of reactions with both increases and decreases in gastric tone and, during the remifentanil infusion, glucagon did not affect gastric tone. CONCLUSIONS: Remifentanil induced changes in gastric tone with both increases and decreases. The effect of remifentanil on gastric tone is probably dependent on the current state of the systems involved.

The effect of anesthetic technique on early postoperative gastric emptying: comparison of propofol-remifentanil and opioid-free sevoflurane anesthesia.

PURPOSE: A postoperative decrease in the gastric emptying (GE) rate may delay the early start of oral feeding and alter the bioavailability of orally administered drugs. The aim of this study was to compare the effect on early gastric emptying between two anesthetic techniques. METHODS: Fifty patients (age, 19-69 years) undergoing day-case laparoscopic cholecystectomy were randomly assigned to received either total intravenous anesthesia with propofol/remifentanil/rocuronium (TIVA; n = 25) or inhalational opioid-free anesthesia with sevoflurane/rocuronium (mask induction; GAS; n = 25). Postoperative gastric emptying was evaluated by the acetaminophen method. After arrival in the recovery unit, acetaminophen (paracetamol) 1.5 g was given through a nasogastric tube, and blood samples were drawn during a 2-h period. The area under the serum-acetaminophen concentration curve from 0-60 min (AUC60), the maximal concentration (Cmax), and the time to reach C-max (Tmax) were calculated. RESULTS: Twelve patients were excluded due to surgical complications (e.g., conversion to open surgery) and difficulty in drawing blood samples (TIVA, n = 7; GAS, n = 5). Gastric emptying parameters were (mean +/- SD): TIVA, AUC60, 2458 +/- 2775 min.micromol.l(-1); Cmax, 71 +/- 61 micromol.l(-1); and Tmax, 81 +/- 37 min; and GAS, AUC60, 2059 +/- 2633 min.micromol.l(-1); Cmax, 53 +/- 53 micromol.l(-1); and Tmax, 83 +/- 41 min. There were no significant differences between groups. CONCLUSION: There was no major difference in early postoperative gastric emptying between inhalation anesthesia with sevoflurane versus total intravenous anesthesia with propofol-remifentanil. Both groups showed a pattern of delayed gastric emptying, and the variability in gastric emptying was high. Perioperative factors other than anesthetic technique may have more influence on gastric emptying.

The delay of gastric emptying induced by remifentanil is not influenced by posture.

Posture has an effect on gastric emptying. In this study, we investigated whether posture influences the delay in gastric emptying induced by opioid analgesics. Ten healthy male subjects underwent 4 gastric emptying studies with the acetaminophen method. On two occasions the subjects were given a continuous infusion of remifentanil (0.2 microg. kg(-1). min(-1)) while lying either on the right lateral side in a 20 degrees head-up position or on the left lateral side in a 20 degrees head-down position. On two other occasions no infusion was given, and the subjects were studied lying in the two positions. When remifentanil was given, there were no significant differences between the two postures in maximal acetaminophen concentration (right side, 34 micromol. L(-1); versus left side, 16 micromol. L(-1)), time taken to reach the maximal concentration (94 versus 109 min), or area under the serum acetaminophen concentration time curve from 0 to 60 min (962 versus 197 min. micromol. L(-1)). In the control situation, there were differences between the postures in maximal acetaminophen concentration (138 versus 94 micromol. L(-1); P < 0.0001) and area under the serum acetaminophen concentration time curves from 0 to 60 min (5092 versus 3793 min. micromol. L(-1); P < 0.0001), but there was no significant difference in time taken to reach the maximal concentration (25 versus 47 min). Compared with the control situation, remifentanil delayed gastric emptying in both postures. We conclude that remifentanil delays gastric emptying and that this delay is not influenced by posture.