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Objectives: Opioids are important for postoperative analgesia but their use can be associated with numerous side effects. Transcutaneous electrical nerve stimulation (TENS) has been used for acute pain treatment and has dose-dependent analgesic effects, and therefore presents an alternative to intravenous (iv) opioids for postoperative pain relief. The aim of this meta-analysis was to compare high-frequency, high-intensity (HFHI or intense) TENS to iv opioids with regard to postoperative pain intensity, recovery time in the Post Anesthesia Care Unit (PACU) and opioid consumption after elective gynecological surgery., Methods: We searched Medline, Embase, Web of Science, Cochrane, Amed and Cinahl for RCTs and quasi-experimental studies (2010-2022), and WHO and ClinicalTrials.gov for ongoing/unpublished studies. Meta-analysis and subsequent Trial Sequential Analysis (TSA) was performed for all stated outcomes. Quality of evidence was assessed according to GRADE., Results: Only three RCTs met the inclusion criteria (362 participants). The surgical procedures involved surgical abortion, gynecologic laparoscopy and hysteroscopy. The applied TENS frequency was 80 Hz and intensity 40-60 mA. There was no difference in pain intensity according to Visual Analogue Scale (VAS) at discharge from PACU between the TENS and opioid group (MD VAS -0.15, 95 % CI -0.38 to 0.09) (moderate level of evidence). Time in PACU was significantly shorter in the TENS group (MD -15.2, 95 % -22.75 to -7.67), and this finding was manifested by TSA (high-level of evidence). Opioid consumption in PACU was lower in the TENS group (MD Morphine equivalents per patient mg -3.42, 95 % -4.67 to -2.17) (high-level of evidence)., Conclusions: There was no detectable difference in postoperative pain relief between HFHI TENS and iv opioids after gynecological surgery. Moreover, HFHI TENS decreases recovery time and opioid consumption in PACU. HFHI TENS may be considered an opioid-sparing alternative for postoperative pain relief after gynecological surgery., Systematic Review Registration: PROSPERO CRD42021231048., (© 2023 the author(s), published by De Gruyter, Berlin/Boston.)

Background: Opioid-based treatment is used to manage stress responses during surgery and postoperative pain. However, opioids have both acute and long-term side effects, calling for opioid-free anaesthetic strategies. This meta-analysis compares adverse events, postoperative recovery, discharge time from post-anaesthesia care unit, and postoperative pain, nausea, vomiting, and opioid consumption between strict opioid-free and opioid-based general anaesthesia., Methods: We conducted a systematic review and meta-analysis. We searched PubMed, Embase, Cinahl, Cochrane Library, selected reference lists, and Google Scholar. We included randomised controlled trials (RCTs) published between January 2000 and February 2021 with at least one opioid-free study arm, i.e. no opioids administered preoperatively, during anaesthesia induction, before skin closure, or before emergence from anaesthesia., Results: The study comprised 1934 patients from 26 RCTs. Common interventions included laparoscopic gynaecological surgery, upper gastrointestinal surgery, and breast surgery. There is firm evidence that opioid-free anaesthesia significantly reduced adverse postoperative events (OR 0.32, 95% CI 0.22 to 0.46, I 2  = 56%, p < 0.00001), mainly driven by decreased nausea (OR 0.27, (0.17 to 0.42), p < 0.00001) and vomiting (OR 0.22 (0.11 to 0.41), p < 0.00001). Postoperative opioid consumption was significantly lower in the opioid-free group (-6.00 mg (-8.52 to -3.48), p < 0.00001). There was no significant difference in length of post-anaesthesia care unit stay and overall postoperative pain between groups., Conclusions: Opioid-free anaesthesia can improve postoperative outcomes in several surgical settings without evidence of adverse effects on patient safety and pain management. There is a need for more evidence-based non-opioid anaesthetic protocols for different types of surgery as well as postoperative phases., (© 2021 The Authors. Acta Anaesthesiologica Scandinavica published by John Wiley & Sons Ltd on behalf of Acta Anaesthesiologica Scandinavica Foundation.)

Background/aim: A number of patients continue to suffer from chronic abdominal pain of unknown origin, which may also lead to a prolonged use of opioid analgesics. Symptoms of abdominal pain, nausea and vomiting in this patient group resemble the characteristics of the Roux stasis Syndrome. The aim was to elucidate relationships between chronic abdominal pain, Roux limb motor activity and opioid analgesics., Methods: Roux limb high-resolution manometry and ratings of abdominal pain and quality of life were analysed in 15 gastric bypass patients reporting abdominal pain of unknown origin. Effect of acute opiate administration (morphine i.v.) on fasting Roux limb motor activity was assessed in asymptomatic and morphine-naïve gastric bypass patients (n = 9) and compared with an untreated control group (n = 11)., Results: In the symptomatic patient group, we found disturbed Roux limb motor patterns in 10 out of 15 examinations, but no signs of Roux stasis syndrome. A high prevalence of prescribed opioid analgesics as well as a high number of reoperations in this group. The worst quality of life and the highest number of pain-killing medications were observed among the patients with distal pacemaker activity in Roux limb. In the morphine-naïve and asymptomatic patients, morphine increased the muscular tone in the Roux limb during phase III-like motor activity. A majority of the RYGBP patients with chronic abdominal pain had a disturbed Roux limb fasting motility, and there was a high prevalence of prescribed opioid analgesics. In opiate-naïve RYGBP patients, acute morphine intravenously increased the muscular tone of the Roux limb.

Context: Practice varies regarding the use of opioids during rapid sequence induction. Controversy exists as to whether opioids may increase the risk of pulmonary aspiration by decreasing the barrier pressure (lower oesophageal sphincter-intragastric pressure)., Objectives: To evaluate the effects of adding alfentanil during anaesthesia induction with propofol with respect to the barrier pressure in the oesophagogastric junction., Participants and Setting: Seventeen healthy volunteers (11 men and six women) participated in a double-blind, randomised, crossover trial at the University Hospital in Orebro, Sweden., Interventions and Outcome Measures: The volunteers were anaesthetised on two different occasions, randomly assigned to receive either alfentanil 20 μg kg(-1) or an equivalent amount of isotonic saline, administered intravenously, 1 min before induction with propofol 2 mg kg(-1). One minute after propofol administration, a cricoid pressure of 30 N was applied. The primary outcome was the difference in the change in barrier pressure between the alfentanil and the placebo occasion 1 min after propofol administration. The secondary outcomes were differences in the changes in barrier pressure 1 min after alfentanil or placebo administration and during ongoing cricoid pressure application., Results: There were no statistically significant differences in barrier pressure, at any time point, between anaesthesia induction with alfentanil and propofol compared with induction with placebo and propofol. The barrier pressure never decreased to less than 2.4 mmHg in any volunteer., Conclusion: Our study showed no increased risk regarding the integrity of the gastro-oesophageal junction when alfentanil is added during an induction with propofol in volunteers. This supports the practice of adding opioids as adjuvants during rapid sequence induction.

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.

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.