Wilderness Medical Society Clinical Practice Guidelines for the Treatment of Acute Pain in Austere Environments: 2024 Update.

The Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the management of pain in austere environments. Recommendations are graded based on the quality of supporting evidence as defined by criteria put forth by the American College of Chest Physicians. This is an update of the 2014 version of the "WMS Practice Guidelines for the Treatment of Acute Pain in Remote Environments" published in Wilderness & Environmental Medicine 2014; 25:41-49.

General Anesthesia for Cesarean Delivery for Thrombocytopenia in Hypertensive Disorders of Pregnancy: Findings From the Obstetric Airway Management Registry.

BACKGROUND: In resource-limited environments, spinal anesthesia (SA) is preferred for cesarean delivery. In women at risk of spinal epidural hematoma, particularly those with hypertensive disorders of pregnancy, thrombocytopenia should be excluded before neuraxial blockade. In the context of emergency surgery for fetal distress, this investigation may be hampered by laboratory services being unavailable or off-site. METHODS: The Obstetric Airway Management Registry (ObAMR) is currently active across all anesthesia training institutions affiliated with the University of Cape Town. This multicenter observational study aimed to estimate the proportion of patients receiving general anesthesia (GA) for either confirmed or suspected thrombocytopenia, which was not excluded due to unavailability of laboratory results. To establish the number of GA uses that may have been avoided if platelet counts were available, we retrospectively searched for subsequent platelet counts in patients for whom thrombocytopenia was suspected. An algorithm was proposed, including a simple decision aid for estimating risk versus benefit of SA versus GA, to be followed in the setting of hypertensive disorders of pregnancy and thrombocytopenia. RESULTS: Thrombocytopenia was the indication for GA in 100 of 591 patients (16.9%) captured in the registry. In total, 48 of 591 (8.1%) had confirmed thrombocytopenia, and 52 of 591 (8.8%) had suspected thrombocytopenia. Of these patients, 91 of 100 had a hypertensive disorder of pregnancy. In the confirmed thrombocytopenia group, the indication for GA was a platelet count <75 × 10 9 /L. In the suspected thrombocytopenia group, 46 of 52 (88.5%) platelet counts could be retrospectively traced. The median (interquartile range) platelet count was 178 × 10 9 /L (93 - 233 × 10 9 /L), and platelets exceeded 75 × 10 9 /L in 41 of 46 patients (89.1%). In the 5 of 46 patients with retrospectively confirmed thrombocytopenia, 2 had hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, 2 had antepartum hemorrhage with preeclampsia, and 1 had isolated thrombocytopenia with preeclampsia. CONCLUSIONS: In 17% of patients, the indication for GA was thrombocytopenia. Of these, 52 of 100, or nearly 9% of the total of 591, received GA because a platelet count was unavailable at the time of surgery. The importance of early laboratory assessment, when available, should be emphasized. Overall, 41 of 591 (6.9%) had a platelet count >75 × 10 9 /L and would not have needed GA if their platelet count had been known. After following the constructed algorithm and applying the decision aid to assess risk and benefit, there may be circumstances in which the clinician justifiably opts for SA when a platelet count is indicated but unavailable.

Effects of the Lubo cervical collar on airway patency in awake adults - A magnetic resonance imaging study.

INTRODUCTION: Intended for use by prehospital first responders, the Lubo TM cervical collar is an adjustable, radiolucent, single-use device that incorporates a mechanical jaw thrust mechanism. The combination enables non-invasive airway management in cases of trauma where cervical motion restriction is necessary. The potential benefits include use as an airway adjuvant maintaining upper airway patency, reducing provider task loading. The limited research on the device efficacy and safety requires further investigation. METHODS: A randomized, crossover, interventional study was performed to compare mean differences in airway patency at the level of the uvula, epiglottis, tongue and soft palate with and without the Lubo collar in awake volunteers using magnetic resonance imaging (MRI). Fourteen participants each underwent two MRI scans of the upper airway: A control scan with no Lubo collar, and an intervention scan with the Lubo collar applied and jaw thrust mechanism activated. Two independent radiologists measured anterior-posterior diameter of the airway at four anatomical levels on the resulting MRI images. RESULTS: There was no significant difference in mean airway diameter between the control and intervention measurements at any level. Mean (SD; 95% CI: p-value) differences were 0.9 mm (-2.38; 2.3 to 0.5; p=0.17) at the epiglottis, 0.5 mm (1.6; -0.5 to 1.4; p=0.29) at the soft palate, 0.2 mm (2.86; -1.4 to 1.9; p = 0.78) at the tongue, 0.4 mm (4.04; -1.9 to 2.7; p = 0.72) at the uvula. CONCLUSION: The Lubo TM airway collar did not show a significant change in upper airway patency at four anatomical levels measured in awake adult participants. Further research is required to investigate its clinical use in patients that are unable to maintain upper airway tone. Groups of interest would include trauma, obstructive sleep apnoea, obesity and patients under general anaesthesia.

Intubation during spinal motion restriction using the LuboTM cervical collar - a manikin simulation study.

Introduction: The LuboTM collar is a cervical motion restriction device featuring a unique external jaw-thrust mechanism designed to provide non-invasive airway patency. In addition, tracheal intubation is facilitated by releasing an anterior chin strap; this allows better mouth opening than the previous generation of semi-rigid cervical collars. This study aimed to compare tracheal intubation using the LuboTM collar combined with manual in-line stabilization (MILS) to intubation with MILS alone. The primary outcome was the time to successful intubation. Secondary outcomes compared intubation success rate, Cormack-Lehane grade, ease of intubation and dental trauma. Methods: A randomized, cross-over, equivalence study was performed. Eighty full-time physician anaesthesia providers were recruited. Participants performed tracheal intubation using direct laryngoscopy on a manikin under two different scenarios: with the LuboTM collar and MILS applied, and with MILS and no cervical collar. The time to successful intubation was measured and compared using two-one-sided and paired t-tests. Results: Intubation times fell well within the a priori equivalence limits of 10 seconds, with a mean difference (95% CI) of 0.52 seconds (-1.30 to 2.56). There was no significant difference in intubation time with the LuboTM collar (mean [SD] 19.2 [4.5] seconds) compared to the MILS alone group (19.7 [5.2] seconds). The overall success rate was 98.7% in the Lubo group and 100% in the MILS group. Adequate laryngoscopy views (Cormack-Lehane grades I to IIb) were equivalent between groups (Lubo 92.5% versus MILS alone 93.7%). Conclusion: In this manikin-based study, the time to intubation with the LuboTM collar and MILS applied was equivalent to time to intubation with MILS alone, with similar intubating conditions. Thus, the LuboTM collar and MILS may simplify airway management by reducing the number of steps required to perform intubation in patients requiring cervical motion restriction.

Prospective Observational Trial of a Nonocclusive Dilatation Balloon in the Management of Tracheal Stenosis.

OBJECTIVES: Tracheal stenosis is a debilitating condition that often presents as an emergency and is challenging to treat. Dilatation may avoid tracheostomy or costly tracheal resection and reconstruction. Traditional dilators cause complete occlusion, preventing oxygenation and ventilation, limiting the safe duration of dilatation, and increasing the risk of hypoxic injury or barotrauma. The study authors here assessed an innovative nonocclusive tracheal dilatation balloon, which may improve patient safety by allowing continuous gas exchange. DESIGN: A prospective observational study of 20 discrete dilatation procedures performed in 13 patients under general anesthesia. The primary outcomes were the ability to ventilate during dilatation and the preservation of peripheral oxygen saturation. Secondary outcomes included a measured reduction in stenosis, improvement in Cotton-Myer grading, and procedure-related adverse events. SETTING: At a single university (academic) hospital. PARTICIPANTS: Consenting adult patients with acquired tracheal stenosis. INTERVENTIONS: Access to the airway was maintained by a rigid bronchoscope or supraglottic airway device, as deemed appropriate. Continuous conventional ventilation was provided during 3-minute balloon dilatations. MEASUREMENTS AND MAIN RESULTS: Heart rate, airway pressure, end-tidal carbon dioxide partial pressure, and peripheral oxygen saturation were measured, and adverse events were recorded. Ventilation was satisfactory in all patients. Peripheral saturation remained greater than 94% in 19 of the 20 (95%) procedures. Stenosis internal diameter and grading were improved. Two patients had minor reversible adverse events (coughing and laryngospasm), which did not prevent completion of the procedure. CONCLUSIONS: The authors report the first human trial of the device, in which continuous conventional ventilation could be provided during all tracheal balloon dilatation procedures. Larger trials are needed to confirm improved patient safety and comparative efficacy.

Adapted full-face snorkel masks as an alternative for COVID-19 personal protection during aerosol generating procedures in South Africa: A multi-centre, non-blinded in-situ simulation study.

INTRODUCTION: SARS-CoV-2 has resulted in increased worldwide demand for personal protective equipment (PPE). With pressure from ongoing epidemic and endemic episodes, we assessed an adapted snorkel mask that provides full-face protection for healthcare workers (HCWs), particularly during aerosol-generating procedures. These masks have a custom-made adaptor which allows the fitment of standard medical respiratory filters. The aim of this study was to evaluate the fit, seal and clinical usability of these masks. METHODS: This multicentre, non-blinded in-situ simulation study recruited fifty-two HCWs to don and doff the adapted snorkel mask. Negative pressure seal checks and a qualitative fit test were performed. The HCWs completed intubation and extubation of a manikin in a university skills training laboratory, followed by a web-based questionnaire on the clinical usability of the masks. RESULTS: Whilst fit and usability data were generally satisfactory, two of the 52 participants (3.8%) felt that the mask did not span the correct distance from the nose to the chin, and 3 of 34 participants (8.8%) who underwent qualitative testing with a Bitrex test failed. The majority of users reported no fogging, humidity or irritation. It was reportedly easy to speak while wearing the mask, although some participants perceived that they were not always understood. Twenty-one participants (40%) experienced a subjective physiological effect from wearing the mask; most commonly a sensation of shortness of breath. DISCUSSION: A fit-tested modified full-face snorkel mask may offer benefit as a substitute for N95 respirators and face shields. It is, however, important to properly select the correct mask based on size, fit testing, quality of the three-dimensional (3D) printed parts and respiratory filter to be used. Additionally, HCWs should be trained in the use of the mask, and each mask should be used by a single HCW and not shared.

Aerosol boxes and barrier enclosures for airway management in COVID-19 patients: a scoping review and narrative synthesis.

Exposure of healthcare providers to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a significant safety concern during the coronavirus disease 2019 (COVID-19) pandemic, requiring contact/droplet/airborne precautions. Because of global shortages, limited availability of personal protective equipment (PPE) has motivated the development of barrier-enclosure systems, such as aerosol boxes, plastic drapes, and similar protective systems. We examined the available evidence and scientific publications about barrier-enclosure systems for airway management in suspected/confirmed COVID-19 patients. MEDLINE/Embase/Google Scholar databases (from December 1, 2019 to May 27, 2020) were searched for all articles on barrier enclosures for airway management in COVID-19, including references and websites. All sources were reviewed by a panel of experts using a Delphi method with a modified nominal group technique. Fifty-two articles were reviewed for their results and level of evidence regarding barrier device feasibility, advantages, protection against droplets and aerosols, effectiveness, safety, ergonomics, and cleaning/disposal. The majority of analysed papers were expert opinions, small case series, technical descriptions, small-sample simulation studies, and pre-print proofs. The use of barrier-enclosure devices adds to the complexity of airway procedures with potential adverse consequences, especially during airway emergencies. Concerns include limitations on the ability to perform airway interventions and the aid that can be delivered by an assistant, patient injuries, compromise of PPE integrity, lack of evidence for added protection of healthcare providers (including secondary aerosolisation upon barrier removal), and lack of cleaning standards. Enclosure barriers for airway management are no substitute for adequate PPE, and their use should be avoided until adequate validation studies can be reported.

Clinical Evaluation of Measuring the ACT during Elective Cardiac Surgery with Two Different Devices.

Unfractionated heparin is the mainstay of anticoagulation during cardiac surgery on cardiopulmonary bypass (CPB) due to its low cost, quick onset, and ease of reversal. Since over 30 years, the activated clotting time (ACT) has been used to assess the level of heparin activity both before and after CPB. We compared two different methods of measuring the ACT: i-STAT, which uses amperometric detection of thrombin cleavage, and Hemochron Jr, which is based on detecting viscoelastic changes in blood. We included 402 patients from three institutions (Papworth Hospital, Cambridge, UK; Groote Schuur, Cape Town, South Africa; University Hospital Basel, Basel, Switzerland) undergoing elective cardiac surgery on CPB in our study. We analyzed duplicate samples on both devices at all standard measuring points during the procedure. The correlation coefficient between two Hemochron and two i-STAT devices was .9165 and .9857, respectively. The within-subject coefficient of variation (WSCV) ranged from 8.2 to 13.6% for the Hemochron and from 4.1 to 9.1% for the i-STAT. We found that the number of occasions where one of the duplicate readings was >1,000 seconds while the other was below or close to the clinically significant threshold of 400 seconds were higher for the Hemochron. We found the i-STAT to systematically return higher measurements. We conclude that the i-STAT provides a more reliable test for heparin activity and assesses safe anticoagulation during cardiac surgery on pump. The fact the that the i-STAT reads higher than the Hemochron leads to the recommendation to validate the methods against each other before changing devices.

Core Temperature Monitoring in Obstetric Spinal Anesthesia Using an Ingestible Telemetric Sensor.

BACKGROUND: Perioperative hypothermia may affect maternal and neonatal outcomes after obstetric spinal anesthesia. Core temperature is often poorly monitored during spinal anesthesia, due to the lack of an accurate noninvasive core temperature monitor. The aim of this study was to describe core temperature changes and temperature recovery during spinal anesthesia for elective cesarean delivery. We expected that obstetric spinal anesthesia would be associated with a clinically relevant thermoregulatory insult (core temperature decrease >1.0°C). METHODS: A descriptive study was conducted in 28 women. An ingestible telemetric temperature sensor was used to record core temperature over time (measured every 10 seconds). The primary outcome was the maximum core temperature decrease after spinal anesthetic injection. The secondary outcomes were lowest absolute core temperature, time to lowest temperature, time to recovery of core temperature, hypothermic exposure (degree-hours below 37.0°C), and the time-weighted hypothermic exposure (median number of degrees below 37.0°C per hour). Basic descriptive statistics, median spline smooth, and integration of the area below the 37.0°C line of the temperature-over-time curve were utilized to analyze the data. RESULTS: Intestinal temperature decreased by a mean (standard deviation) of 1.30°C (0.31); 99% confidence interval (CI), 1.14 to 1.46 after spinal anesthetic injection. The median (interquartile range [IQR]) time to temperature nadir was 0.96 (0.73-1.32) hours (95% CI, 0.88-1.22). Fourteen of the 28 participants experienced intestinal temperatures below 36.0°C after spinal injection. Temperature was monitored for a minimum of 8 hours after spinal injection. In 8 of 28 participants, intestinal temperature did not recover to baseline during the monitored period. A median (IQR) of 4.59 (3.38-5.92) hours (95% CI, 3.45-5.90) was required for recovery to baseline intestinal temperature in the remaining 20 patients. Participants experienced a median (IQR) of 1.97 (1.00-2.68) degree-hours of hypothermic exposure (95% CI, 1.23-2.45). The median (IQR) number of degrees below 37.0°C per hour was 0.45 (0.35-0.60) (95% CI, 0.36-0.58). CONCLUSIONS: During cesarean delivery under spinal anesthesia, women experienced a rapid decrease in core temperature. Using an intestinal telemetric sensor, the perioperative thermal insult and recovery were documented with high resolution. Fifty percent of participants in this study became hypothermic. Although the surgical procedure is typically of short duration, women undergoing spinal anesthesia for cesarean delivery experience significant hypothermic exposure and compromised thermoregulation for several hours.

Comparison of four methods of endotracheal tube passage in simulated airways: There is room for improved techniques.

OBJECTIVE: Endotracheal intubation requires laryngoscopy followed by passage of the endotracheal tube (ETT). Tube passage can be difficult, but there is little evidence to support which adjunct for tube passage is most effective. METHODS: The four tube passage adjuncts tested were the naked ETT, stylet ETT, railroaded bougie and preloaded bougie. Participants completed pre- and post-test surveys identifying demographics, experience and method preference. After instruction, participants completed eight intubations on manikins with 'easy' and 'difficult' airways. RESULTS: One hundred and seventeen practitioners who were experienced emergency medicine physicians, anaesthesiologists and out-of-hospital providers completed 936 total ETT attempts. For the 'difficult' airway, the percentage first pass success (95% confidence interval [CI]) for the naked ETT was 30.8% (23.1-39.7%). This was significantly lower than the stylet ETT (95.7% [86.6-100%]), the railroaded bougie (75.2% [63.8-86.6%]), or the preloaded bougie (89.7% [79.7-99.7%]). On difficult airways, the median (interquartile range [IQR]) time-to-intubation was fastest in the stylet ETT (25.0 s [20.9-32.2 s]) with the railroaded bougie being the slowest (43.2 s [36.5-56.2 s]). Seventy-nine per cent of participants stated that they would change their practice based on participating in this study. Participants increased their preference for the preloaded bougie from 30.6% to 69.4%. CONCLUSION: The data show that tube passage with a stylet ETT or a preloaded bougie is superior in terms of higher first pass success, faster time-to-intubation and higher post-test preference. The naked ETT is clearly inferior to other methods. This research supports the recommendation to use a stylet ETT or bougie for every predicted difficult intubation.

Preeclampsia in 2017: Obstetric and Anaesthesia Management.

In many centres, anaesthesia now incorporates perioperative medicine. Preeclampsia is a perioperative medical challenge requiring a multi-disciplinary team. New definitions stress the rapid progression of the disease and highlight the importance of early detection. Anaesthesiologists should understand the pathophysiology of the disease and develop the ultrasound skills required to assist in the assessment of disease severity. This facilitates the choice of anaesthesia method and perioperative management in complicated cases. Regional anaesthesia remains central, but there are important developments in the practice of general anaesthesia, if indicated. Appropriate haemodynamic monitoring should be established. Anaesthesiologists should also lead the resuscitation team in the management of cardiorespiratory failure and coagulopathy.