Chronic post amputation pain: pathophysiology and prevention options for a heterogenous phenomenon.

PURPOSE OF REVIEW: Chronic postamputation pain (cPAP) remains a clinical challenge, and current understanding places a high emphasis on prevention strategies. Unfortunately, there is still no evidence-based regimen to reliably prevent chronic pain after amputation. RECENT FINDINGS: Risk factors for the development of phantom limb pain have been proposed. Analgesic preventive interventions are numerous and no silver bullet has been found. Novel techniques such as neuromodulation and cryoablation have been proposed. Surgical techniques focusing on reimplantation of the injured nerve might reduce the incidence of phantom limb pain after surgery. SUMMARY: Phantom limb pain is a multifactorial process involving profound functional and structural changes in the peripheral and central nervous system. These changes interact with individual medical, psychosocial and genetic patient risk factors. The patient collective of amputees is very heterogeneous. Available evidence suggests that efforts should focus on prevention of phantom limb pain, since treatment is notoriously difficult. Questions as yet unanswered include the evidence-base of specific analgesic interventions, their optimal "window of opportunity" where they may be most effective, and whether patient stratification according to biopsychosocial risk factors can help guide preventive therapy.

The effectiveness of a low-dose esketamine versus an alfentanil adjunct to propofol sedation during endoscopic retrograde cholangiopancreatography: A randomised controlled multicentre trial.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is one of the most complex gastrointestinal endoscopic procedures. Currently, it is still unclear which sedation regimen best facilitates an ERCP. The N-methyl-D-aspartate receptor antagonist esketamine has anaesthetic, analgesic and sympathomimetic properties and is known to cause less cardiorespiratory depression than other sedatives. It could therefore be an ideal adjunct to propofol for deep sedation. OBJECTIVE: To assess the effectiveness of esketamine versus alfentanil as an adjunct to propofol target-controlled infusion (TCI) for deep sedation during ambulant ERCP. DESIGN: A randomised controlled multicentre study. SETTING: Endoscopic intervention suite at an academic and general hospital in the Netherlands. PARTICIPANTS: Adult, American Society of Anesthesiologists Physical Status I to III patients scheduled to undergo ERCP. INTERVENTION: Consecutive patients were randomly assigned to receive sedation for an ERCP with propofol TCI and alfentanil (group A) or with propofol TCI and esketamine (group E). MAIN OUTCOME MEASURES: The primary outcome was effectiveness of the sedation regimen expressed as the total dose of propofol - as a surrogate parameter - necessary to perform ERCP in a satisfactory manner for endoscopist and patients. Secondary outcomes were recovery time, patients' and endoscopists' satisfaction with sedation, side effects (e.g. psychotomimetic effects, nausea and vomiting) and the number of respiratory and cardiovascular adverse events. RESULTS: Data from 162 patients were analysed. The total dose of propofol required was significantly lower in group E (n=83) (8.3 mg kg h) than in group A (n=79) (10.5 mg kg h) (P < 0.001). There were no significant differences in recovery time, patients' and endoscopists' satisfaction, side effects, psychotomimetic effects and the number of sedation-related adverse events. CONCLUSION: Low-dose esketamine reduces the total amount of propofol necessary for sedation during ERCP in American Society of Anesthesiologists I and II patients without affecting recovery time, satisfaction of patients and endoscopists, side effects and respiratory or cardiovascular adverse events, when compared with alfentanil. TRIAL REGISTRATION: The Netherlands Trial Register (NTR5486).

Effect of a Machine Learning-Derived Early Warning System for Intraoperative Hypotension vs Standard Care on Depth and Duration of Intraoperative Hypotension During Elective Noncardiac Surgery: The HYPE Randomized Clinical Trial.

Importance: Intraoperative hypotension is associated with increased morbidity and mortality. A machine learning-derived early warning system to predict hypotension shortly before it occurs has been developed and validated. Objective: To test whether the clinical application of the early warning system in combination with a hemodynamic diagnostic guidance and treatment protocol reduces intraoperative hypotension. Design, Setting, and Participants: Preliminary unblinded randomized clinical trial performed in a tertiary center in Amsterdam, the Netherlands, among adult patients scheduled for elective noncardiac surgery under general anesthesia and an indication for continuous invasive blood pressure monitoring, who were enrolled between May 2018 and March 2019. Hypotension was defined as a mean arterial pressure (MAP) below 65 mm Hg for at least 1 minute. Interventions: Patients were randomly assigned to receive either the early warning system (n = 34) or standard care (n = 34), with a goal MAP of at least 65 mm Hg in both groups. Main Outcomes and Measures: The primary outcome was time-weighted average of hypotension during surgery, with a unit of measure of millimeters of mercury. This was calculated as the depth of hypotension below a MAP of 65 mm Hg (in millimeters of mercury) × time spent below a MAP of 65 mm Hg (in minutes) divided by total duration of operation (in minutes). Results: Among 68 randomized patients, 60 (88%) completed the trial (median age, 64 [interquartile range {IQR}, 57-70] years; 26 [43%] women). The median length of surgery was 256 minutes (IQR, 213-430 minutes). The median time-weighted average of hypotension was 0.10 mm Hg (IQR, 0.01-0.43 mm Hg) in the intervention group vs 0.44 mm Hg (IQR, 0.23-0.72 mm Hg) in the control group, for a median difference of 0.38 mm Hg (95% CI, 0.14-0.43 mm Hg; P = .001). The median time of hypotension per patient was 8.0 minutes (IQR, 1.33-26.00 minutes) in the intervention group vs 32.7 minutes (IQR, 11.5-59.7 minutes) in the control group, for a median difference of 16.7 minutes (95% CI, 7.7-31.0 minutes; P < .001). In the intervention group, 0 serious adverse events resulting in death occurred vs 2 (7%) in the control group. Conclusions and Relevance: In this single-center preliminary study of patients undergoing elective noncardiac surgery, the use of a machine learning-derived early warning system compared with standard care resulted in less intraoperative hypotension. Further research with larger study populations in diverse settings is needed to understand the effect on additional patient outcomes and to fully assess safety and generalizability. Trial Registration: ClinicalTrials.gov Identifier: NCT03376347.

European Society of Anaesthesiology Task Force on Nitrous Oxide: a narrative review of its role in clinical practice.

Nitrous oxide (N2O) is one of the oldest drugs still in use in medicine. Despite its superior pharmacokinetic properties, controversy remains over its continued use in clinical practice, reflecting in part significant improvements in the pharmacology of other anaesthetic agents and developing awareness of its shortcomings. This narrative review describes current knowledge regarding the clinical use of N2O based on a systematic and critical analysis of the available scientific literature. The pharmacological properties of N2O are reviewed in detail along with current evidence for the indications and contraindications of this drug in specific settings, both in perioperative care and in procedural sedation. Novel potential applications for N2O for the prevention or treatment of chronic pain and depression are also discussed. In view of the available evidence, we recommend that the supply of N2O in hospitals be maintained while encouraging its economic delivery using modern low flow delivery systems. Future research into its potential novel applications in prevention or treatment of chronic conditions should be pursued to better identify its role place in the developing era of precision medicine.

[Adjuvants in modern anesthesia - lidocaine]. / Adjuvanzien in der modernen Anästhesie - Lidocain.

Local anesthetics (LA) are well known for their antinociceptive and antiarrhythmic properties, but exert alternative effects, i.e. anti-inflammatory activity, as well. These immunomodulatory properties might contribute to the beneficial effects observed in the clinical setting, when intravenous lidocaine is given perioperatively. Systemic LA were shown to attenuate postoperative pain, accelerate the return of bowel function and shorten length of hospital stay in patients undergoing abdominal surgery.

[Adjuvants in modern anesthesia - magnesium]. / Adjuvanzien in der modernen Anästhesie - Magnesium.

Magnesium plays a key role in many cellular functions and there is growing interest in its role in perioperative medicine. While experimental studies provided promising results for several disease states, clinical trials mainly gave conflicting results. This review article summarizes current knowledge on the homeostasis of magnesium as well as on its proposed indications and recommendations in the clinical setting.

Local anaesthetics: 10 essentials.

This review seeks to address 10 essential questions regarding the clinical use of local anaesthetics. Each local anaesthetic has distinctive physicochemical properties but with the same mode of action; they block voltage-gated sodium channels in the axon. Sodium channel block is brought about by a conformational change and the creation of a positive charge in the channel pore. Different local anaesthetics can reach the local anaesthetic binding site in the axon from the cytoplasmic compartment (classic hydrophilic pathway), or directly via its lipid membrane (hydrophobic pathway), or can enter via large-pore channels (alternative hydrophilic pathway). Beyond the nervous system, local anaesthetics exert beneficial effects on pain and can affect the inflammatory response and the haemostatic system. There are problems with the efficacy of local anaesthetics in the presence of local inflammation, and with significant intravascular toxicity, which can be fatal. But when preventive measures are taken, the incidence of cardiac arrest is low. Intralipid has been proposed to treat systemic local anaesthetic overdose and has been enthusiastically adopted worldwide, even though the mechanism of action is incompletely understood. Intralipid is an aid to the management of local anaesthetic toxicity rather than an antidote and meticulous conduct of regional anaesthesia remains paramount. All local anaesthetics are toxic, in a dose- and time-dependent manner, on virtually all tissues, including nerves and muscles. The question of whether local anaesthetics protect against perioperative tumour progression cannot be answered at this moment, and results from clinical (retrospective) studies are equivocal. Future areas of interest will be the design of new subtype-specific sodium channel blockers, but as we look forward, older local anaesthetics such as 2-chloroprocaine are being reintroduced into the clinical setting. Multimodal perineural analgesia and liposomal bupivacaine may replace catheter techniques for some indications.

Minimally invasive versus open oesophagectomy for patients with oesophageal cancer: a multicentre, open-label, randomised controlled trial.

BACKGROUND: Surgical resection is regarded as the only curative option for resectable oesophageal cancer, but pulmonary complications occurring in more than half of patients after open oesophagectomy are a great concern. We assessed whether minimally invasive oesophagectomy reduces morbidity compared with open oesophagectomy. METHODS: We did a multicentre, open-label, randomised controlled trial at five study centres in three countries between June 1, 2009, and March 31, 2011. Patients aged 18-75 years with resectable cancer of the oesophagus or gastro-oesophageal junction were randomly assigned via a computer-generated randomisation sequence to receive either open transthoracic or minimally invasive transthoracic oesophagectomy. Randomisation was stratified by centre. Patients, and investigators undertaking interventions, assessing outcomes, and analysing data, were not masked to group assignment. The primary outcome was pulmonary infection within the first 2 weeks after surgery and during the whole stay in hospital. Analysis was by intention to treat. This trial is registered with the Netherlands Trial Register, NTR TC 2452. FINDINGS: We randomly assigned 56 patients to the open oesophagectomy group and 59 to the minimally invasive oesophagectomy group. 16 (29%) patients in the open oesophagectomy group had pulmonary infection in the first 2 weeks compared with five (9%) in the minimally invasive group (relative risk [RR] 0·30, 95% CI 0·12-0·76; p=0·005). 19 (34%) patients in the open oesophagectomy group had pulmonary infection in-hospital compared with seven (12%) in the minimally invasive group (0·35, 0·16-0·78; p=0·005). For in-hospital mortality, one patient in the open oesophagectomy group died from anastomotic leakage and two in the minimally invasive group from aspiration and mediastinitis after anastomotic leakage. INTERPRETATION: These findings provide evidence for the short-term benefits of minimally invasive oesophagectomy for patients with resectable oesophageal cancer. FUNDING: Digestive Surgery Foundation of the Unit of Digestive Surgery of the VU University Medical Centre.

Safety and effectiveness using dexmedetomidine versus propofol TCI sedation during oesophagus interventions: a randomized trial.

BACKGROUND: Endoscopic treatment of early neoplastic lesions in oesophagus has evolved as a valid and less invasive alternative to surgical resection. These endoscopic interventions are minimal invasive treatment options usually done with sedation on an outpatient basis. The aim of this trial is to determine the safety and effectiveness of dexmedetomidine sedation compared to the standard used propofol TCI sedation during endoscopic oesophageal interventions. METHODS: The study will be performed as a randomized controlled trial. The first 64 consenting patients will be randomized to either the propofol or the dexmedetomidine group. Following endoscopy patients and gastroenterologists have to fill in questionnaires (PSSI, CSSI) (see abbreviations) about their sedation experiences. Additionally, patients have to accomplish the Trieger test before and after the procedure. Patient monitoring includes time adapted HR, SO2, ECG, NIBP, exCO2, NICO, sweat conductance measurement, OAA/S, and the Aldrete score. Effectiveness of sedation, classified by satisfaction levels and pain and sedation score measured by questionnaires is the primary outcome parameter. Respiratory and hemodynamic complications are surrogate parameters for the secondary outcome parameter "safety". DISCUSSION: The acceptance level among patients after propofol sedation is high. Dexmedetomidine is a relatively new representative for procedural sedation. Has this new form of conscious sedation the potential to be safer and more effective for patients and endoscopists than propofol during endoscopic oesophageal interventions? TRIAL REGISTRATION: This trial is registered in the ISRCTN Register (ISRCTN 68599804). It will be conducted in accordance with the protocol and in compliance with the moral, ethical, and scientific principles governing clinical research as set out in the Declaration of Helsinki (1989) and Good Clinical Practice (GCP). The Departments of Anesthesiology and Gastroenterology & Hepatology of the Academic Medical Center of Amsterdam are responsible for the design and conduct of the trial.

Opioid-free anesthesia: A systematic review and meta-analysis.

STUDY OBJECTIVE: To evaluate all available evidence thus far on opioid based versus opioid-free anesthesia and its effect on acute and chronic postoperative pain. DESIGN: Systematic review and meta-analysis of randomized clinical trials. SETTING: Operating room, postoperative recovery room and ward. PATIENTS: Patients undergoing general anesthesia. INTERVENTIONS: After consulting MEDLINE, EMBASE and Cochrane database, studies which compared opioid free anesthesia (OFA) with opioid based anesthesia (OBA) were included (last search April 15th 2022). MEASUREMENTS: Primary outcomes were acute and chronic pain scores in NRS or VAS. Secondary outcomes were quality of recovery and postoperative opioid consumption. Risk of bias was assessed using the RoB2 tool and a random effects model for the meta-analysis was conducted. MAIN RESULTS: We identified 1245 citations, of which 38 studies met our inclusion criteria. There is moderate quality evidence showing no clinically relevant difference of Numeric Rating Scale (NRS) scores or opioid consumption in the postoperative period (pooled mean difference of 0.39 points with a CI of 0.19-0.59 and 4.02 MME with a CI of 1.73-6.30). We found only one small-sized study reporting no effect of opioid-free anesthesia on chronic pain. The quality of recovery was superior in patients with opioid-free anesthesia (mean difference of 8.26 points), however, this pooled analysis was comprised of only two studies. Postoperative nausea and vomiting (PONV) occurred less in opioid-free anesthesia, but bradycardia was more frequent. CONCLUSIONS: We concluded that we cannot recommend one strategy over the other. Future studies could focus on quality of recovery as outcome measure and adequately powered studies on the effects of opioid-free anesthesia on chronic pain are eagerly awaited.

Changes in ventilator settings and ventilation-induced lung injury in burn patients-A systematic review.

OBJECTIVE: Ventilation strategies aiming at prevention of ventilator-induced lung injury (VILI), including low tidal volumes (VT) and use of positive end-expiratory pressures (PEEP) are increasingly used in critically ill patients. It is uncertain whether ventilation practices changed in a similar way in burn patients. Our objective was to describe applied ventilator settings and their relation to development of VILI in burn patients. DATA SOURCES: Systematic search of the literature in PubMed and EMBASE using MeSH, EMTREE terms and keywords referring to burn or inhalation injury and mechanical ventilation. STUDY SELECTION: Studies reporting ventilator settings in adult or pediatric burn or inhalation injury patients receiving mechanical ventilation during the ICU stay. DATA EXTRACTION: Two authors independently screened abstracts of identified studies for eligibility and performed data extraction. DATA SYNTHESIS: The search identified 35 eligible studies. VT declined from 14 ml/kg in studies performed before to around 8 ml/kg predicted body weight in studies performed after 2006. Low-PEEP levels (<10 cmH2O) were reported in 70% of studies, with no changes over time. Peak inspiratory pressure (PIP) values above 35 cmH2O were frequently reported. Nevertheless, 75% of the studies conducted in the last decade used limited maximum airway pressures (≤35 cmH2O) compared to 45% of studies conducted prior to 2006. Occurrence of barotrauma, reported in 45% of the studies, ranged from 0 to 29%, and was more frequent in patients ventilated with higher compared to lower airway pressures. CONCLUSION: This systematic review shows noticeable trends of ventilatory management in burn patients that mirrors those in critically ill non-burn patients. Variability in available ventilator data precluded us from drawing firm conclusions on the association between ventilator settings and the occurrence of VILI in burn patients.

The effect of requesting a reason for non-adherence to a guideline in a long running automated reminder system for PONV prophylaxis.

BACKGROUND: Automated reminders are employed frequently to improve guideline adherence, but limitations of automated reminders are becoming more apparent. We studied the reasons for non-adherence in the setting of automated reminders to test the hypothesis that a separate request for a reason in itself may further improve guideline adherence. METHODS: In a previously implemented automated reminder system on prophylaxis for postoperative nausea and vomiting (PONV), we included additional automated reminders requesting a reason for non-adherence. We recorded these reasons in the pre-operative screening clinic, the OR and the PACU. We compared adherence to our PONV guideline in two study groups with a historical control group. RESULTS: Guideline adherence on prescribing and administering PONV prophylaxis (dexamethasone and granisetron) all improved compared to the historical control group (89 vs. 82% (p< 0.0001), 96 vs 95% (not significant) and 90 vs 82% (p<0.0001)) while decreasing unwarranted prescription for PONV prophylaxis (10 vs. 13 %). In the pre-operative screening clinic, the main reason for not prescribing PONV prophylaxis was disagreement with the risk estimate by the decision support system. In the OR/PACU, the main reasons for not administering PONV prophylaxis were: 'unintended non-adherence' and 'failure to document'. CONCLUSIONS: In this study requesting a reason for non-adherence is associated with improved guideline adherence. The effect seems to depend on the underlying reason for non-adherence. It also illustrates the importance of human factors principles in the design of decision support. Some reasons for non-adherence may not be influenced by automated reminders.