Intraoperative pharmacologic opioid minimisation strategies and patient-centred outcomes after surgery: a scoping review.

BACKGROUND: Postoperative patient-centred outcome measures are essential to capture the patient's experience after surgery. Although a large number of pharmacologic opioid minimisation strategies (i.e. opioid alternatives) are used for patients undergoing surgery, it remains unclear which strategies are most promising in terms of patient-centred outcome improvements. This scoping review had two main objectives: (1) to map and describe evidence from clinical trials assessing the patient-centred effectiveness of pharmacologic intraoperative opioid minimisation strategies in adult surgical patients, and (2) to identify promising pharmacologic opioid minimisation strategies. METHODS: We searched MEDLINE, Embase, CENTRAL, Web of Science, and CINAHL databases from inception to February 2023. We included trials investigating the use of opioid minimisation strategies in adult surgical patients and reporting at least one patient-centred outcome. Study screening and data extraction were conducted independently by at least two reviewers. RESULTS: Of 24,842 citations screened for eligibility, 2803 trials assessed the effectiveness of intraoperative opioid minimisation strategies. Of these, 457 trials (67,060 participants) met eligibility criteria, reporting at least one patient-centred outcome. In the 107 trials that included a patient-centred primary outcome, patient wellbeing was the most frequently used domain (55 trials). Based on aggregate findings, dexmedetomidine, systemic lidocaine, and COX-2 inhibitors were promising strategies, while paracetamol, ketamine, and gabapentinoids were less promising. Almost half of the trials (253 trials) did not report a protocol or registration number. CONCLUSIONS: Researchers should prioritise and include patient-centred outcomes in the assessment of opioid minimisation strategy effectiveness. We identified three potentially promising pharmacologic intraoperative opioid minimisation strategies that should be further assessed through systematic reviews and multicentre trials. Findings from our scoping review may be influenced by selective outcome reporting bias. STUDY REGISTRATION: OSF - https://osf.io/7kea3.

Effectiveness of dexmedetomidine on patient-centred outcomes in surgical patients: a systematic review and Bayesian meta-analysis.

BACKGROUND: Dexmedetomidine is increasingly used for surgical patients requiring general anaesthesia. However, its effectiveness on patient-centred outcomes remains uncertain. Our main objective was to evaluate the patient-centred effectiveness of intraoperative dexmedetomidine for adult patients requiring surgery under general anaesthesia. METHODS: We conducted a systematic search of MEDLINE, Embase, CENTRAL, Web of Science, and CINAHL from inception to October 2023. Randomised controlled trials (RCTs) comparing intraoperative use of dexmedetomidine with placebo, opioid, or usual care in adult patients requiring surgery under general anaesthesia were included. Study selection, data extraction, and risk of bias assessment were performed by two reviewers independently. We synthesised data using a random-effects Bayesian regression framework to derive effect estimates and the probability of a clinically important effect. For continuous outcomes, we pooled instruments with similar constructs using standardised mean differences (SMDs) and converted SMDs and credible intervals (CrIs) to their original scale when appropriate. We assessed the certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Our primary outcome was quality of recovery after surgery. To guide interpretation on the original scale, the Quality of Recovery-15 (QoR-15) instrument was used (range 0-150 points, minimally important difference [MID] of 6 points). RESULTS: We identified 49,069 citations, from which 44 RCTs involving 5904 participants were eligible. Intraoperative dexmedetomidine administration was associated with improvement in postoperative QoR-15 (mean difference 9, 95% CrI 4-14, n=21 RCTs, moderate certainty of evidence). We found 99% probability of any benefit and 88% probability of achieving the MID. There was a reduction in chronic pain incidence (odds ratio [OR] 0.42, 95% CrI 0.19-0.79, n=7 RCTs, low certainty of evidence). There was also increased risk of clinically significant hypotension (OR 1.98, 95% CrI 0.84-3.92, posterior probability of harm 94%, n=8 RCTs) and clinically significant bradycardia (OR 1.74, 95% CrI 0.93-3.34, posterior probability of harm 95%, n=10 RCTs), with very low certainty of evidence for both. There was limited evidence to inform other secondary patient-centred outcomes. CONCLUSIONS: Compared with placebo or standard of care, intraoperative dexmedetomidine likely results in meaningful improvement in the quality of recovery and chronic pain after surgery. However, it might increase clinically important bradycardia and hypotension. SYSTEMATIC REVIEW PROTOCOL: PROSPERO (CRD42023439896).

Prospective cohort study of topical versus general anaesthesia for flexible bronchoscopy.

BACKGROUND: Topical anaesthesia (TA) and general anaesthesia (GA) are performed for flexible bronchoscopy (FB) worldwide. However, few studies have compared the two anaesthesia methods in terms of perioperative discomforts. METHODS: 648 patients undergoing FB were recruited in Shanghai Pulmonary Hospital, a specialised medical centre in China, from January 2019 to December 2019. The patients underwent FB under TA or GA. The TA group received 1% lidocaine by nasal route, and the GA group received total intravenous anaesthesia. The level of perioperative discomfort and patient satisfaction were assessed. The investigators were blind to the group allocation. RESULTS: Finally, 239 patients received TA and 182 patients received GA. The basic demographic properties were comparable between two groups. There were no significant differences in terms of sore throat, 61.5% in TA group vs 57.1% in GA group. However, there was a significant difference in terms of postoperative nausea and vomiting (34.3% in TA group vs 56.6% in GA group), and dizziness (37.7% in TA group vs 78% in GA group). There was a significant difference in terms of total complication scores (17.2 ± 5.1 in TA group vs 7.7 ± 4.3 in GA group) and satisfaction degree of patients (2.6 ± 1.1 in TA group vs 4.3 ± 0.8 in GA group). CONCLUSIONS: Compared with TA, GA significantly reduced the total complication scores of perioperative discomforts and improved the satisfaction score of patients for FB. TRIAL REGISTRATION NUMBER: This clinical trial was registered with www.chictr.org.cn (ChiCTR1800019971).

Effect of CYB2B6 (c.516G>T), CYP2C9 (c.1075A>C) and UGT1A9 (c.98T>C) polymorphisms on propofol pharmacokinetics in patients submitted to colonoscopy: a cohort study.

BACKGROUND: The aim of this study was to investigate the effect of CYB2B6 (c.516G>T, rs3745274), CYP2C9 (c.1075A>C, rs1057910) and UGT1A9 (c.98T>C, rs72551330) polymorphisms on the pharmacokinetics of single-drug propofol in adult patients undergoing intravenous sedation. METHODS: In this prospective clinical study, a total of 124 patients undergoing anaesthesia with propofol, as a single drug, were evaluated when undergoing colonoscopy procedure. Clinical variables were obtained from the patient's anamnesis prior to performing the anaesthetic procedure, in the moment of the patient's loss of consciousness, during the colonoscopy exam (recorded every 5 min) and in the awakening time. RESULTS: Polymorphic genotypes for the rs3745274 and rs1057910 polymorphisms were associated with bispectral index, target-controlled infusion (TCI)/effector concentration of propofol and TCI/plasma concentration of propofol values. Based on multivariate analysis, it was observed that weight, age, surgery time, systolic blood pressure and the rs1057910 polymorphism corresponded to predictive values for the dose of propofol used. Weight (B = 4.807±0.897), age (B = 1.834±0.834) and duration of surgery (B = 8.164±1.624) corresponded to factors associated with increased propofol dose, while systolic blood pressure (B = -1.892±0.679) and the genotypes (AA vs CA) of the single nucleotide polymorphism (SNP) rs1057910 CYPP2C9 gene (B = -74.161±26.820) decreased the total dose of propofol used. CONCLUSION: We concluded that the rs1057910 and rs3745274 polymorphisms affect the metabolism of propofol in patients exclusively submitted to this drug. Thus, the knowledge of the polymorphic genotypes of the CYPP2C9 and CYB2B6 genes may be predictive of different metabolising phenotypes, suggesting expected behaviours of BIS parameter in the anaesthetic procedure, which contributes to safer monitoring by anaesthesiologists during the clinical intervention.

Prospective cohort study of topical versus general anaesthesia for flexible bronchoscopy.

BACKGROUND: Topical anaesthesia (TA) and general anaesthesia (GA) are performed for flexible bronchoscopy (FB) worldwide. However, few studies have compared the two anaesthesia methods in terms of perioperative discomforts. METHODS: 648 patients undergoing FB were recruited in Shanghai Pulmonary Hospital, a specialised medical centre in China, from January 2019 to December 2019. The patients underwent FB under TA or GA. The TA group received 1% lidocaine by nasal route, and the GA group received total intravenous anaesthesia. The level of perioperative discomfort and patient satisfaction were assessed. The investigators were blind to the group allocation. RESULTS: Finally, 239 patients received TA and 182 patients received GA. The basic demographic properties were comparable between two groups. There were no significant differences in terms of sore throat, 61.5% in TA group vs 57.1% in GA group. However, there was a significant difference in terms of postoperative nausea and vomiting (34.3% in TA group vs 56.6% in GA group), and dizziness (37.7% in TA group vs 78% in GA group). There was a significant difference in terms of total complication scores (17.2 ± 5.1 in TA group vs 7.7 ± 4.3 in GA group) and satisfaction degree of patients (2.6 ± 1.1 in TA group vs 4.3 ± 0.8 in GA group). CONCLUSIONS: Compared with TA, GA significantly reduced the total complication scores of perioperative discomforts and improved the satisfaction score of patients for FB. TRIAL REGISTRATION NUMBER: This clinical trial was registered with www.chictr.org.cn (ChiCTR1800019971).

Effect of CYB2B6 (c.516G>T), CYP2C9 (c.1075A>C) and UGT1A9 (c.98T>C) polymorphisms on propofol pharmacokinetics in patients submitted to colonoscopy: a cohort study.

BACKGROUND: The aim of this study was to investigate the effect of CYB2B6 (c.516G>T, rs3745274), CYP2C9 (c.1075A>C, rs1057910) and UGT1A9 (c.98T>C, rs72551330) polymorphisms on the pharmacokinetics of single-drug propofol in adult patients undergoing intravenous sedation. METHODS: In this prospective clinical study, a total of 124 patients undergoing anaesthesia with propofol, as a single drug, were evaluated when undergoing colonoscopy procedure. Clinical variables were obtained from the patient's anamnesis prior to performing the anaesthetic procedure, in the moment of the patient's loss of consciousness, during the colonoscopy exam (recorded every 5 min) and in the awakening time. RESULTS: Polymorphic genotypes for the rs3745274 and rs1057910 polymorphisms were associated with bispectral index, target-controlled infusion (TCI)/effector concentration of propofol and TCI/plasma concentration of propofol values. Based on multivariate analysis, it was observed that weight, age, surgery time, systolic blood pressure and the rs1057910 polymorphism corresponded to predictive values for the dose of propofol used. Weight (B = 4.807±0.897), age (B = 1.834±0.834) and duration of surgery (B = 8.164±1.624) corresponded to factors associated with increased propofol dose, while systolic blood pressure (B = -1.892±0.679) and the genotypes (AA vs CA) of the single nucleotide polymorphism (SNP) rs1057910 CYPP2C9 gene (B = -74.161±26.820) decreased the total dose of propofol used. CONCLUSION: We concluded that the rs1057910 and rs3745274 polymorphisms affect the metabolism of propofol in patients exclusively submitted to this drug. Thus, the knowledge of the polymorphic genotypes of the CYPP2C9 and CYB2B6 genes may be predictive of different metabolising phenotypes, suggesting expected behaviours of BIS parameter in the anaesthetic procedure, which contributes to safer monitoring by anaesthesiologists during the clinical intervention.

Evaluation of a survey for acute care programme directors on the utilisation of point-of-care ultrasound.

PURPOSE: Point-of-care ultrasound (POCUS) is ultrasound brought to the patient's bedside and performed in 'real time' by the healthcare provider. The utility of POCUS to facilitate management of the acutely ill patient has been demonstrated for multiple pathologies. However, the integration of ultrasonography and echocardiography training into residency curriculum varies across the acute care specialties. STUDY DESIGN: After an institutional review board approval, anaesthesiology, emergency medicine, family medicine, internal medicine, paediatrics and general surgery programme directors (PDs) were surveyed. The survey consisted of 11 questions evaluating the primary bedside assessment tool for common acute care situations, POCUS topics that the PDs were comfortable practising and topics that the PDs felt were useful for their specialty. Barriers to POCUS use, certification and documentation were also surveyed. RESULTS: Overall, 270 PD surveys were completed. The preferred primary assessment tool for common acute care situations varied with specialty; emergency medicine PDs consistently responded that POCUS was the diagnostic modality of choice (p<0.0001). The majority of the PDs reported lack of educational opportunities as the primary barrier to learning POCUS (64%). Most PDs indicated that POCUS examinations should be documented (95.7%), and 39% reported that departmental certification would be sufficient. CONCLUSIONS: This study is the first to evaluate differences in the preferred initial bedside assessment tool between the acute care specialties. Although POCUS is a superior tool for evaluating acute pathologies, disconnect between education and utilisation remains. This study highlights the need to incorporate POCUS into the acute care specialty curriculum.

Developing a blended learning postgraduate teaching programme in anaesthesia: pandemic and beyond.

One of the many challenges facing doctors in training during the COVID-19 pandemic was a significant reduction in postgraduate medical education in the form of formal teaching. Consequently, we sought to provide a blended and asynchronous teaching programme that would be delivered to anaesthetic trainees preparing for their postgraduate examinations. Six sessions of 90-minute duration were delivered during the months July, August and September 2020. Each of the six sessions was delivered live using a variety of online educational tools in addition to traditional didactic-style teaching by the presenters. Participants submitted requests for topics to be covered by the presenters in the final of the six sessions. The sessions were recorded and later uploaded onto an online educational learning platform for viewing at the participants' discretion. The live nature of the sessions ensured participant interaction and a sense of community that trainees had come to expect from previous face-to-face teaching sessions prior to the COVID-19 pandemic. Evaluation was via qualitative and quantitative means using preset questions using the Likert scale and a free-text comments box. The results demonstrated positive feedback across all sessions with particular relevance to the interactive element of the course, the content and delivery. This article describes the requirement for a method of continuing postgraduate medical education in an era where traditional face-to-face teaching is not possible and how the introduction of various innovative educational applications and resources can be used to further postgraduate medical education in the future.

Efficacy of ultrasound guidance for lumbar punctures: a systematic review and meta-analysis of randomised controlled trials.

Ultrasound guidance has been reported to facilitate the performance of lumbar punctures (LPs). However, the use of ultrasound guidance has not yet received consistent conclusions. We performed a systematic review and meta-analysis to determine the efficacy of ultrasound-guided LPs. PubMed, Embase and the Cochrane Library were searched for randomised controlled trials comparing ultrasound guidance with traditional palpation for LPs in adults. The primary outcome was risk of failed procedures. A random-effects Mantel-Haenzsel model or random-effects inverse variance model was used to calculate relative risks (RRs) or standardised mean differences (SMDs) with 95% CIs. Twenty-eight trials (N=2813) met the inclusion criteria. Ultrasound-guided LPs were associated with a reduced risk of failed procedures (RR=0.58, 95% CI 0.39 to 0.85, p=0.005). No significant heterogeneity was detected (I2=27%) among these trials. It further decreased first attempt to failure (RR=0.43, 95% CI 0.30 to 0.62, p<0.00001), mean attempts to success (SMD=-0.61, 95% CI -0.80 to -0.43, p=0.00001) and incidences of complications of headache and backache (RR=0.63, 95% CI 0.46 to 0.85, p=0.003). Ultrasound guidance is an effective technique for LPs in adults.

Simple budget-neutral tool to improve intraoperative communication.

BACKGROUND: Communication failure is a common cause of medical errors and adverse events. Within the operating room (OR), there are many barriers to good communication, which can adversely affect patient outcome. OBJECTIVE: Implementing a simple, cost-neutral tool aimed at improving intraoperative communication and engagement. METHODS: Three anaesthesiology residents collected data using a data sheet and tailored surveys distributed to OR staff. Data were collected over a 2-week period in 2019, with 1 week each of preintervention and postintervention data collection. The intervention consisted of wearing OR caps displaying the first name and role of the anaesthesia resident clearly on the front. RESULTS: A total of 20 data sheets and 48 preintervention and postintervention surveys were collected for a response rate of 57%. There was a statistically significant increase in OR staff knowledge of the anaesthesia resident's name (66% vs 100%, p=<0.001), an increase in the mean number of times the surgical providers addressed the anaesthesia residents (3.6 vs 7.8, p=0.0074) and an increase in the mean number of times the surgical providers addressed them by their first name (0.7 vs 4, p=0.0067). Comments received during the intervention were positive with overwhelming support. CONCLUSIONS: This study demonstrated that a simple, cost-effective intervention can result in dramatic improvement in intraoperative communication and engagement between teams.

Pre-operative fasting in adults and children: clinical practice and guidelines.

It is widely recognised that prolonged fasting for elective surgery in both children and adults serves no purpose, adversely affects patient well-being and can be detrimental. Although advised fasting times for solids remain unchanged, there is good evidence to support a 1-h fast for children, with no increase in risk of pulmonary aspiration. In adults, a major focus has been the introduction of carbohydrate loading before anaesthesia, so that patients arrive for surgery not only hydrated but also in a more normal metabolic state. The latter attenuates some of the physiological responses to surgery, such as insulin resistance. As in children, there is no increase in risk of pulmonary aspiration. Further data are required to guide best practice in patients with diabetes.

How do trainee doctors introduce themselves to patients?

OBJECTIVES: To identify how trainee doctors introduce themselves to patients. DESIGN: Survey. SETTING: Chelsea and Westminster Hospital, London. PARTICIPANTS: One hundred trainee doctors, of mixed grades and specialties. MAIN OUTCOME MEASURES: Introducing oneself by name, using their professional title 'Dr', use of the term 'trainee'. RESULTS: All 100 participants introduced themselves by name to patients, with 63% using only their first name, 18% using only their last name and 18% using a combination of both. 67% mentioned their specialty and 18% mentioned their training grade. 85% identified themselves as a doctor, but only 22% used their professional title (Dr), and only 6% introduced themselves by name, grade, specialty and title. 80% varied the way they introduced themselves to patients, depending on several factors including the clinical situation and patients' characteristics/features. 56% said that they had changed the way they introduced themselves over time, and 42% deliberately avoided the term 'trainee' during introductions. There was no association between trainees' age, gender or specialty and their comfort in describing themselves as 'trainees', but the more junior trainees were more comfortable using this term than the senior grades (p<0.0001). Overall, 76% disliked the term 'trainee', for various reasons. CONCLUSION: All doctors in this study introduced themselves by name but the majority did not specify their training grade or trainee status, predominantly because they believed it could trigger anxiety around their competence or undermine confidence in their abilities.

Comparison of the effects of ultrasound-guided quadratus lumborum block and erector spinae plane block on postoperative pain in abdominal surgeries: a protocol for systematic review and meta-analysis.

INTRODUCTION: Ultrasound-guided quadratus lumborum block and erector spinae plane block are widely used for postoperative analgesia in adult patients undergoing abdominal surgeries. This protocol aims to compare the analgesic effects between ultrasound-guided quadratus lumborum block and erector spinae plane block on postoperative pain in abdominal surgeries. METHODS AND ANALYSIS: Four databases, including PubMed, EMBASE, Web of Science and the Cochrane Central Register of Controlled Trials (CENTRAL), will be searched. Randomised controlled trials that compared the analgesic effects between ultrasound-guided quadratus lumborum block and erector spinae plane block on postoperative pain in adult patients will be identified. The primary outcomes are time to the first analgesic request and postoperative analgesic consumption over 24 hours. Secondary outcomes will include postoperative pain scores and the incidence of side effects. RevMan V.5.3 software will be used for data processing and statistical analysis. The Grading of Recommendation, Assessment, Development and Evaluation approach will be used to assess the evidence quality of outcomes. ETHICS AND DISSEMINATION: Ethical approval is not required for this study. Results of this present study will be submitted to a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD42023445802.

Effect of pectineus muscle plane block versus femoral nerve block for postoperative analgesia and early recovery after knee surgery: a randomised controlled trial study protocol.

BACKGROUND: Femoral nerve block (FNB) is a prevalent method used for postoperative pain management after knee surgery; however, it decreases the strength of the quadriceps muscle and is not conducive to early recovery after surgery. Pectineus muscle plane (PMP) block involves the injection of a local anaesthetic into the fascial plane below the pectineus muscle, where it blocks the obturator and saphenous nerves. However, there is little evidence on the effectiveness of PMP block for analgesia after knee surgery. The aim of this trial is to assess whether PMP block can improve postoperative analgesia, promote early recovery and reduce the length of hospital stay. METHODS AND ANALYSIS: In this randomised controlled study, 46 patients will be randomly allocated into two groups: the PMP block group (n=23) and the FNB group (n=23). The primary outcome measures will include Visual Analog Scale scores for pain at rest and during movement at various time points following knee surgery. Secondary outcomes will include the degree of active flexion, straight leg raise test performance, get-out-of-bed test result, 20 m walk test result, total dose administered via patient-controlled analgesia infusion pumps, hospital stay duration, patient satisfaction and postoperative complications, such as pulmonary embolism and deep vein thrombosis.This study protocol adheres to rigorous standards for ethical conduct and patient safety. The findings from this trial are expected to contribute valuable insights to the optimisation of postoperative pain management strategies and the improvement of early recovery outcomes for patients who undergo knee surgery. ETHICS AND DISSEMINATION: This trial has been approved by the ethics committee of Zhejiang Hospital (2022(128K)) on 17 November 2022, and inpatients who meet the inclusion criteria and diagnostic requirements are eligible for this study. Any subsequent protocol and informed consent document amendments must be approved by the responsible ethics committee. All communications with the regulatory authorities and the ethics committee must be recorded. All recruited patients will be informed of the trial purposes and their duties within the trial before randomisation. Recruited patients can withdraw from the study at any time without providing any specific reason. The patient data will be stored in a separate, safe place, but that it may be reviewed by the relevant investigator. The results will be published in international peer-reviewed medical journals. TRIAL REGISTRATION NUMBER: http://www.chictr.org.cn, ID: ChiCTR2300076018. Registered on 21 September 2023.

Evaluation of the early use of norepinephrine in major abdominal surgery on medical and surgical postoperative complications: study protocol for a randomised controlled trial (EPON STUDY).

BACKGROUND: Post-induction anaesthesia often promotes intraoperative hypotension (IOH) that can worsen postoperative outcomes. This study aims to assess the benefit of norepinephrine versus ephedrine at the induction of anaesthesia to prevent postoperative complications following major abdominal surgery by preventing IOH. METHODS AND ANALYSIS: The EPON STUDY is a prospective single-centre randomised controlled trial with the planned inclusion of 500 patients scheduled for major abdominal surgery at the Amiens University Hospital. The inclusion criteria are patients aged over 50 years weighing more than 50 kg with an American Society of Anesthesiologists physical status score of ≥2 undergoing major abdominal surgery under general anaesthesia. Patients are allocated either to the intervention group (n=250) or the standard group (n=250). In the intervention group, the prevention of post-induction IOH is performed with norepinephrine (dilution to 0.016 mg/mL) using an electric syringe pump at a rate of 0.48 mg/h (30 mL/h) from the start of anaesthesia and then titrated to achieve the haemodynamic target. In the control group, the prevention of post-induction IOH is performed with manual titration of ephedrine, with a maximal dose of 30 mg, followed by perfusion with norepinephrine. In both groups, the haemodynamic target to maintain is a mean arterial pressure (MAP) of 65 mm Hg or 70 mm Hg for patients with a medical history of hypertension. An intention-to-treat analysis will be performed. The primary outcome is the Clavien-Dindo score assessed up to 30 days postoperatively. The secondary endpoints are the length of hospital stay and length of stay in an intensive care unit/postoperative care unit; postoperative renal function; postoperative cardiovascular, respiratory, neurological, haematological and infectious complications at 1 month; and volume of intraoperative vascular filling and mortality at 1 month. ETHICS AND DISSEMINATION: Ethical approval was obtained from the committee of protection of the persons of Ile de France in May 2021 (number 21 05 41). The authors will be involved in disseminating the research findings (through attending conferences and co-authoring papers). The results of the study will be disseminated via peer-reviewed publications and presentations at national and international conferences. TRIAL REGISTRATION NUMBER: NCT05276596.

Diamedica Draw-over Vaporiser: bench testing the UK Defence Anaesthesia System in the deployed environment.

INTRODUCTION: The Diamedica Draw-over Vaporiser 2 (DDV2) is the sevoflurane vaporiser used by the UK Defence Medical Services to provide deployed volatile general anaesthesia. The Defence Anaesthesia System employs the DDV2 with a turbine-driven ventilator as a 'push-over' vaporiser, a modification from the manufacturer's design. We investigated sevoflurane delivery at varying minute volumes (MVs), vaporiser settings and temperatures in this configuration. METHODS: A range of DDV2 settings (1%, 2%, 3%, 4% and induction) and MVs (2, 4, 6 and 8 L/min at 12 ventilations per minute) were tested at two ambient temperatures (20 and 30±3°C) over 30 min. A supplemental experiment, simulating anaesthesia during damage control surgery, was also completed, where he DDV2 was set to 2% with a 6 L/min MV for 90 min. RESULTS: In both experiments, two distinct phases of sevoflurane delivery were noted, a 'wash-in phase' followed by a 'maintenance period'. The wash-in phase normally lasted less than 5 min. During the maintenance period at low MVs and vaporiser settings the DDV2 delivered a constant output, while at higher MVs and settings vapour output fell predictably. At 20±3°C, using DDV2 settings likely to be encountered in clinical practice, sevoflurane delivery was within 20% of that set. Higher vaporiser settings, MVs and temperatures resulted in greater variation between vaporiser setting and agent delivery. This variation is explained by the incomplete temperature compensation of the DDV2. CONCLUSIONS: The DDV2 functions predictably at a range of settings, MVs and temperatures. Anaesthetic delivery in the defence anaesthesia configuration is like that previously described in the draw-over configuration. The equipment was found to be reliable and robust. This experimental work supports the continued use of the Defence Anaesthesia System for the delivery of and training in deployed general anaesthesia.

Effect of a 3D-printed reconstruction automated matching system for selecting the size of a left double-lumen tube: a study protocol for a prospective randomised controlled trial.

INTRODUCTION: Lung isolation is primarily accomplished using a double-lumen tube (DLT) or bronchial blocker. A precise and accurate size of the DLT is a prerequisite for ensuring its accurate placement. Three-dimensional (3D) reconstruction technology can be used to accurately reproduce tracheobronchial structures to improve the accuracy of DLT size selection. Therefore, we have developed automatic comparison software for 3D reconstruction based on CT data (3DRACS). In this study, we aimed to evaluate the efficiency of using 3DRACS to select the DLT size for endobronchial intubation in comparison with using the 'blind' DLT intubation method to determine the DLT size, which is based on height and sex. METHODS AND ANALYSIS: This is a prospective, single-centre, double-blind randomised controlled trial. In total, 200 patients scheduled for lung resection using a left DLT will be randomly allocated to the 3D group or the control group at a 1:1 ratio. A 3DRACS will be used for the 3D group to determine the size of the DLT, while in the case of the control group, the size of the DLT will be determined according to patient height and sex. The primary outcome is the success rate of placement of the left DLT without fibreoptic bronchoscopy (FOB). The secondary outcomes include the following: successful intubation time, degree of pulmonary atrophy, grade of airway injury, oxygenation during one-lung ventilation, postoperative sore throat and hoarseness, and number of times FOB is used. ETHICS AND DISSEMINATION: Ethical approval has been obtained from our local ethics committee (approval number: SCCHEC-02-2022-155). Written informed consent will be obtained from all participants before randomisation, providing them with clear instructions about the purpose of the study. The results will be disseminated through peer-reviewed publications and conferences. TRIAL REGISTRATION NUMBER: NCT06258954.