Virtual reality and 3D printing in clinical anesthesia: a case series of two years' experience in a single tertiary medical centre.

PURPOSE: Anatomically correct patient-specific models made from medical imaging can be printed on a three-dimensional (3D) printer or turned into a virtual reality (VR) program. Until recently, use in anesthesia has been limited. In 2019, the anesthesia department at Tel Aviv Medical Center launched a 3D program with the aim of using 3D modelling to assist in preoperative anesthesia planning. METHODS: A retrospective review of all relevant patients between July 2019 and June 2021 referred for preoperative airway planning with 3D modelling. Patient files were reviewed for correlation between the model-based airway plan and the actual airway plan, the type of model used, and any anesthetic complications related to airway management. RESULTS: Twenty patients were referred for 3D modelling. Of these, 15 models were printed, including 12 children requiring one lung ventilation. Five patients had VR reconstructions, including three with mediastinal masses. One patient had both a 3D-printed model and a VR reconstruction. There were two cases (10%) where the model plan did not correlate with the final airway plan and one case where a model could not be created because of poor underlying imaging. For the remaining 17 cases, the plan devised on the model matched the final airway plan. There were no anesthetic complications. CONCLUSIONS: Three-dimensional modelling and subsequent printing or VR reconstruction are feasible in clinical anesthesia. Its routine use for patients with challenging airway anatomy correlated well with the final clinical outcome in most cases. High-quality imaging is essential.

RéSUMé: OBJECTIF: Des modèles anatomiquement corrects spécifiques à un·e patient·e réalisés à partir de l'imagerie médicale peuvent être imprimés sur une imprimante tridimensionnelle (3D) ou transformés en programme de réalité virtuelle (RV). Jusqu'à récemment, l'utilisation de cette modalité était limitée en anesthésie. En 2019, le service d'anesthésie du centre médical de Tel Aviv a lancé un programme 3D dans le but d'utiliser la modélisation 3D pour faciliter la planification préopératoire de l'anesthésie. MéTHODE: Nous avons réalisé un examen rétrospectif de toute la patientèle concernée référée pour une planification préopératoire des voies aériennes avec modélisation 3D entre juillet 2019 et juin 2021. Les dossiers des patient·es ont été examinés pour déterminer la corrélation entre le plan de prise en charge des voies aériennes fondé sur le modèle et le plan fondé sur les voies aériennes réelles, le type de modèle utilisé et toute complication anesthésique liée à la prise en charge des voies aériennes. RéSULTATS: Vingt patient·es ont été référé·es pour la modélisation 3D. À partir de cette cohorte, 15 modèles ont été imprimés, dont 12 pour des enfants nécessitant une ventilation pulmonaire. Cinq patient·es ont bénéficié de reconstructions en RV, dont trois avec des masses médiastinales. Un modèle imprimé en 3D et une reconstruction en RV ont été créés pour une personne. Il y a eu deux cas (10 %) où le plan modèle n'était pas corrélé avec le plan des voies aériennes final et un cas où il n'a pas été possible de créer un modèle en raison d'une mauvaise imagerie sous-jacente. Pour les 17 cas restants, le plan conçu sur le modèle correspondait au plan final de prise en charge des voies aériennes. Il n'y a pas eu de complications anesthésiques. CONCLUSION: La modélisation tridimensionnelle et l'impression ultérieure ou la reconstruction en RV sont réalisables en anesthésie clinique. Leur utilisation systématique pour les patient·es présentant une anatomie difficile au niveau des voies aériennes était bien corrélée avec le résultat clinique final dans la plupart des cas. Une imagerie de haute qualité est essentielle.

A Prospective Observational Crossover Study Comparing Intubation by Pediatric Residents Using Video Laryngoscopy and Direct Laryngoscopy on a Pierre Robin Simulation Manikin.

INTRODUCTION: Video laryngoscopy (VL) has been proposed to increase the likelihood of successful intubation in patients with predicted difficult airways such as those with Pierre Robin sequence (PRS). Prior studies have focused on the performance of anesthesiologists, who are generally considered airway experts. Our primary aim was to investigate the success rate of intubation using VL compared with direct laryngoscopy (DL) when attempted by pediatric residents on a PRS model. METHODS: Participants were administered a 5-minute refresher video on 2 VL techniques (CMAC, conventional geometry VL, and McGrath, unconventional geometry VL) and DL. The participants were asked to intubate the AirSim PRS infant manikin. The order of VL and DL use was randomly selected. All intubations were video recorded, and the recordings were analyzed by 3 anesthesiologists blinded to the participant's identity and previous experience. RESULTS: Seventeen of 23 residents succeeded in intubating the PRS model using DL. Only 9 residents succeeded in intubating the PRS model using VL (conventional or unconventional geometry). Intubation success rate was higher when comparing DL with VL ( P = 0.04) and similar when comparing VL devices ( P = 0.69). DISCUSSION: Contrary to expectation, the intubation success rate was lower using VL than with DL among pediatric residents. This should be considered when designing residency training and in real-life resuscitation.

Optimal protamine dosing after cardiopulmonary bypass: The PRODOSE adaptive randomised controlled trial.

BACKGROUND: The dose of protamine required following cardiopulmonary bypass (CPB) is often determined by the dose of heparin required pre-CPB, expressed as a fixed ratio. Dosing based on mathematical models of heparin clearance is postulated to improve protamine dosing precision and coagulation. We hypothesised that protamine dosing based on a 2-compartment model would improve thromboelastography (TEG) parameters and reduce the dose of protamine administered, relative to a fixed ratio. METHODS AND FINDINGS: We undertook a 2-stage, adaptive randomised controlled trial, allocating 228 participants to receive protamine dosed according to a mathematical model of heparin clearance or a fixed ratio of 1 mg of protamine for every 100 IU of heparin required to establish anticoagulation pre-CPB. A planned, blinded interim analysis was undertaken after the recruitment of 50% of the study cohort. Following this, the randomisation ratio was adapted from 1:1 to 1:1.33 to increase recruitment to the superior arm while maintaining study power. At the conclusion of trial recruitment, we had randomised 121 patients to the intervention arm and 107 patients to the control arm. The primary endpoint was kaolin TEG r-time measured 3 minutes after protamine administration at the end of CPB. Secondary endpoints included ratio of kaolin TEG r-time pre-CPB to the same metric following protamine administration, requirement for allogeneic red cell transfusion, intercostal catheter drainage at 4 hours postoperatively, and the requirement for reoperation due to bleeding. The trial was listed on a clinical trial registry (ClinicalTrials.gov Identifier: NCT03532594). Participants were recruited between April 2018 and August 2019. Those in the intervention/model group had a shorter mean kaolin r-time (6.58 [SD 2.50] vs. 8.08 [SD 3.98] minutes; p = 0.0016) post-CPB. The post-protamine thromboelastogram of the model group was closer to pre-CPB parameters (median pre-CPB to post-protamine kaolin r-time ratio 0.96 [IQR 0.78-1.14] vs. 0.75 [IQR 0.57-0.99]; p < 0.001). We found no evidence of a difference in median mediastinal/pleural drainage at 4 hours postoperatively (140 [IQR 75-245] vs. 135 [IQR 94-222] mL; p = 0.85) or requirement (as a binary outcome) for packed red blood cell transfusion at 24 hours postoperatively (19 [15.8%] vs. 14 [13.1%] p = 0.69). Those in the model group had a lower median protamine dose (180 [IQR 160-210] vs. 280 [IQR 250-300] mg; p < 0.001). Important limitations of this study include an unblinded design and lack of generalisability to certain populations deliberately excluded from the study (specifically children, patients with a total body weight >120 kg, and patients requiring therapeutic hypothermia to <28°C). CONCLUSIONS: Using a mathematical model to guide protamine dosing in patients following CPB improved TEG r-time and reduced the dose administered relative to a fixed ratio. No differences were detected in postoperative mediastinal/pleural drainage or red blood cell transfusion requirement in our cohort of low-risk patients. TRIAL REGISTRATION: ClinicalTrials.gov Unique identifier NCT03532594.

The use of organ donor blood in liver transplantation.

BACKGROUND: Blood removed from organs during deceased donor organ procurement is routinely discarded but is a potential resource for donor-specific transfusion (DST) in subsequent liver transplantation (LT). This study retrospectively analyses the impact of DST on intraoperative bank blood product usage, long-term graft, and patient survival, as well as frequency of rejection post-LT. METHODS: A total of 992 adult LT performed from 1993 to 2018 in a single quaternary center were included. Intraoperative blood product usage, patient, and graft survival, as well as acute and chronic rejection were assessed in patients who received blood retrieved from the organ donor, the "donor blood" (DB) group (n = 437) and patients who did not, the "no donor blood" (NDB) group (n = 555). RESULTS: Processing of DB ensured safe levels of potassium, magnesium, and insulin. There were fewer units of bank red blood cells transfusion required in the DB group compared to NDB group (2 vs. 4 units, P = .01). Graft survival was significantly superior in the DB group (10-year survival 75% vs. 69%, respectively, P = .04) but DST was not an independent predictor of graft survival. There was no significant difference in patient survival or rejection between the groups. There was no difference in treated, biopsy-proven rejection between the two groups. CONCLUSIONS: This is the first large-cohort study assessing long-term outcomes of intraoperative DST in LT. The collection of organ donor blood and subsequent use in LT recipients appeared feasible with appropriate quality checks ensuring safety. DST resulted in a reduction in the use of packed red blood cells. There was no difference in the rate of rejection or graft or patient survival.

Development and validation of a 3D printed antiviral ventilator filter - a comparative study.

BACKGROUND: The current coronavirus infectious disease 2019 (COVID-19) pandemic has caused unexpected pressure on medical supplies, interrupting supply chains and increasing prices. The supply of antiviral filters which form an essential part of the ventilator circuit have been affected by these issues. Three-dimensional (3D) printing may provide a solution to some of these issues. METHODS: We designed and tested 3D printed heat and moisture exchange (HME) and antiviral casing. For each casing we tested two different filter materials derived from a sediment water filter cartridge or 1.5-µm glass fiber filter paper. A polyurethane sponge was used for the HME. Each design was tested for circuit leak, circuit compliance, peak inspiratory pressure and casing integrity using methylene blue dye. RESULTS: We designed, produced, and tested two different types of antiviral filters with six different internal configurations. Overall, we tested 10 modified filter designs and compared them with the original commercial filter. Except for the combination of 1.5-µm filter paper and 5 mm sponge peak inspiratory pressure and circuit compliance of the filters produced were within the operating limits of the ventilator. All In addition, all filters passed the dye test. CONCLUSIONS: Our filter may be of particular importance to those working in low middle-income countries unable to compete with stronger economies. Our design relies on products available outside the healthcare supply chain, much of which can be purchased in grocery stores, hardware stores, or industrial and academic institutions. We hope that these HMEs and viral filters may be beneficial to clinicians who face critical supply chain issues during the COVID-19 pandemic.

Utility of three-dimensional modeling of the fetal airway for ex utero intrapartum treatment.

Recent technological developments in three-dimensional (3D) printing have created new opportunities for applications in clinical medicine. 3D printing has been adopted for teaching and planning complicated surgeries, including maxillofacial, orthopedic reconstructions, and airway manipulation for one-lung ventilation or airway stenting. We present here the first use of such technology to print a model from in utero imaging for intrapartum treatment planning. A 32-week fetus presented with congenital high airway obstruction syndrome (CHAOS) due to a large cervical lymphatic malformation. An ex utero intrapartum treatment (EXIT) procedure was planned to allow delivery of a viable infant. We printed a 3D model of the fetal airway by printing separate elements: mandible, tongue, mass, larynx, and trachea from the fetal MRI. The elements were stuck together maintaining correct anatomical relationships. Airway planning was then performed in consultation with a pediatric ear nose and throat (ENT) surgeon. 3D modeling in utero presents many challenges: the resolution of the 3D model generated from a fetal MRI is less crisp than from CT images, fetal position may be variable and not in a defined anatomical plane, movement artifact occurs. Nevertheless, pre-procedure simulations with the aid of 3D modeling promoted team cooperation and well-prepared management of the fetus during EXIT.

Novel self-fixation chest drain device tested in a swine model of pneumo-hemothorax.

INTRODUCTION: Thoracic injuries account for 20-25% of trauma-related deaths. In cases of pneumothorax the insertion of a chest tube is mandatory but associated with high complication rates particularly when inserted under difficult conditions. The C-Lant is a novel chest-tube insertion device that provides integrated double fixation capabilities and can be used by responders with minimal experience. The aim of the study was to test the device in a large animal model. MATERIAL AND METHODS: Pneumothorax, tension pneumothorax, and hemothorax were induced in four white domestic female pigs. The C-Lant device (Vigor Medical Technologies, Haifa, Israel) was inserted as any chest-drain to decompress the thorax. Pull test was applied to test the strength of device fixation. RESULTS: The insertion of the device was simple and effective without detectable negative physiological effects. Reliable fixation was achieved without difficulty. Air and liquid were promptly drained from the chest cavity. Minimal tissue laceration occurred when applying the device in a scenario of erroneous pneumothorax diagnosis with fully expanded lungs. Interconnection with other surgical accessories was smooth. CONCLUSION: The C-Lant is a novel device that facilitates easy insertion and fixation of chest-tubes by minimally experienced medical providers and reduces the likelihood of unwanted expulsion. Clinical studies are planned.

Anesthesia for Patients Undergoing Anesthesia for Elective Thoracic Surgery During the COVID-19 Pandemic: A Consensus Statement From the Israeli Society of Anesthesiologists.

Anesthesia for thoracic surgery requires specialist intervention to provide adequate operating conditions and one-lung ventilation. The pandemic caused by severe acute respiratory syndrome-associated coronavirus 2 (SARS-CoV-2) is transmitted by aerosol and droplet spread. Because of its virulence, there is a risk of transmission to healthcare workers if appropriate preventive measures are not taken. Coronavirus disease 2019 (COVID-19) patients may show no clinical signs at the early stages of the disease or even remain asymptomatic for the whole course of the disease. Despite the lack of symptoms, they may be able to transfer the virus. Unfortunately, during current COVID-19 testing procedures, about 30% of tests are associated with a false-negative result. For these reasons, standard practice is to assume all patients are COVID-19 positive regardless of swab results. Here, the authors present the recommendations produced by the Israeli Society of Anesthesiologists for use in thoracic anesthesia for elective surgery during the COVID-19 pandemic for both the general population and COVID-19-confirmed patients. The objective of these recommendations is to make changes to some routine techniques in thoracic anesthesia to augment patients' and the medical staff's safety.

National and International Guidelines for Patient Blood Management in Obstetrics: A Qualitative Review.

In developed countries, rates of postpartum hemorrhage (PPH) requiring transfusion have been increasing. As a result, anesthesiologists are being increasingly called upon to assist with the management of patients with severe PPH. First responders, including anesthesiologists, may adopt Patient Blood Management (PBM) recommendations of national societies or other agencies. However, it is unclear whether national and international obstetric societies' PPH guidelines account for contemporary PBM practices. We performed a qualitative review of PBM recommendations published by the following national obstetric societies and international groups: the American College of Obstetricians and Gynecologists; The Royal College of Obstetricians and Gynecologists, United Kingdom; The Royal Australian and New Zealand College of Obstetricians and Gynecologists; The Society of Obstetricians and Gynecologists of Canada; an interdisciplinary group of experts from Austria, Germany, and Switzerland, an international multidisciplinary consensus group, and the French College of Gynaecologists and Obstetricians. We also reviewed a PPH bundle, published by The National Partnership for Maternal Safety. On the basis of our review, we identified important differences in national and international societies' recommendations for transfusion and PBM. In the light of PBM advances in the nonobstetric setting, obstetric societies should determine the applicability of these recommendations in the obstetric setting. Partnerships among medical, obstetric, and anesthetic societies may also help standardize transfusion and PBM guidelines in obstetrics.

High Success Rates Using Ultrasound for Neuraxial Block in Obese Patients.

BACKGROUND: Successful neuraxial block performance relies on assessment and palpation of surface landmarks, potentially challenging in patients with a high body mass index (BMI). OBJECTIVES: To evaluate the use of ultrasound-assisted neuraxial bock in a non-obstetric population with BMI above versus below 30 kg/m2. METHODS: Healthy adult patients undergoing extracorporeal shock wave lithotripsy (ESWL) under neuraxial block were observed in this quality assurance study. Prior to the neuraxial block, an ultrasound examination was performed to identify the puncture site. Neuraxial anesthesia block was performed under aseptic surgical conditions with the patient in the sitting position. Following block placement, external landmarks were palpated. Our primary study outcome was the number of attempts (skin insertions with the needle) after pre-puncture ultrasound identification of the insertion point, comparing patients with BMI above versus below 30 kg/m2. Our secondary outcome was assessment by palpation of external anatomical landmarks. RESULTS: Our study group included 63 consecutive patients undergoing neuraxial block for ESWL. Data were assessed according to BMI (above versus below 30 kg/m2). An overall success rate at the first attempt of 90.5% (CI 0.8-0.95) was achieved using ultrasound-guided neuraxial block. This block placement success rate was similar for all patients, regardless of BMI above versus below 30 kg/m2. In contrast, the ease of palpation of anatomic landmarks, P = 0.001, and the ease of palpation of iliac crest, P < 0.001, differed significantly between the patients above versus below 30 kg/m2. The reported verbal pain scores (VPS) due to block insertion was similar among all patients regardless of BMI category (above versus below 30 kg/m2). CONCLUSIONS: We observed high success rates when ultrasound-assisted neuraxial block is performed, regardless of BMI above versus below 30 kg/m2, despite expected differences in surface landmark palpation.

The association between midazolam premedication and postoperative delirium - a retrospective cohort study.

STUDY OBJECTIVE: To evaluate the association between midazolam premedication and postoperative delirium in a large retrospective cohort of patients ≥70 years. DESIGN: Retrospective cohort study. SETTING: A single tertiary academic medical center. PATIENTS: Patients ≥70 years having elective non-cardiac surgery under general anesthesia from 2020 to 2021. INTERVENTIONS: Midazolam premedication, defined as intravenous midazolam administration prior to induction of general anesthesia. MEASUREMENTS: The primary outcome, postoperative delirium, was a collapsed composite outcome including at least one of the following: a positive 4A's test during post-anesthesia care unit stay and/or the initial 2 postoperative days; physician or nursing records reporting new-onset confusion as captured by the CHART-DEL instrument; or a positive 3D-CAM test. The association between midazolam premedication and postoperative delirium was assessed using multivariable logistic regression, adjusting for potential confounding variables. As secondary analysis, we investigated the association between midazolam premedication and a composite of other postoperative complications. Several sensitivity analyses were performed using similar regression models. MAIN RESULTS: In total, 1973 patients were analyzed (median age 75 years, 47% women, 50% ASA score ≥ 3, 32% high risk surgery). The overall incidence of postoperative delirium was 15.3% (302/1973). Midazolam premedication was administered to 782 (40%) patients (median [IQR] dose 2 [1,2] mg). After adjustment for potential confounding variables, midazolam premedication was not associated with increased odds of postoperative delirium, with adjusted odds ratio of 1.09 (95% confidence interval 0.82-1.45; P = 0.538). Midazolam premedication was also not associated with the composite of other postoperative complications. Furthermore, no association was found between midazolam premedication and postoperative delirium in any of the sensitivity analyses preformed. CONCLUSIONS: Our results suggest that low doses of midazolam can be safely used to pre-medicate elective surgical patients 70 years or older before non-cardiac surgery, without significant effect on the risk of developing postoperative delirium.

Development and Validation of a Hybrid Bronchoscopy Trainer Using Three-Dimensional Printing.

INTRODUCTION: Simulation is an essential component of medical education. Commercially available intubation simulators often lack anatomical fidelity of the lower airway and are therefore not suitable for teaching bronchoscopy or lung isolation. By using a desktop 3-dimensional (3D) printer, we aimed to create and validate a hybrid simulator from an existing mannequin with a 3D-printed lower airway that has anatomical fidelity and is financially affordable compared with commercially available models. METHODS: Using an anonymized computed tomography scan of an adult male patient, we developed a 3D model of the airway from below the larynx to the 3rd generation bronchi, which was then printed on a desktop 3D printer. The printed airway was attached to an existing mannequin below the larynx via a universal adaptor. Ten anesthesiology attendings performed a blinded comparison of the hybrid mannequin with a commercially available mannequin for tactile and visual fidelity when performing intubation, bronchoscopy, and lung isolation. They were also asked to assess the models for educational suitability. RESULTS: The 3D printed model was judged more suitable for teaching double-lumen tube insertion to novice physicians compared with the commercial model, with median (interquartile range) scores of 5 (4-5) versus 3 (2-4), P = 0.017. Similar results were found for bronchial blocker insertion and bronchoscopy. The visual fidelity of the bronchial anatomy was scored as 5 (4-5) and 2 (1-3) for the 3D-printed and the commercial models, respectively (P = 0.007). CONCLUSION: By creating a hybrid model combining an existing commercially available mannequin with a 3D-printed trachea and bronchial tree, we have created an affordable training simulator suitable for teaching lung isolation and bronchoscopy. Enhancing existing mannequins with 3D-printed parts may be of particular interest to institutions that do not have the funds to buy models with anatomical fidelity but do have access to a 3D printer.

Major Pulmonary Resection for Non-Small Cell Lung Carcinoma during the COVID-19 Pandemic-Single Israeli Center Cross-Sectional Study.

BACKGROUND: The highly contagious COVID-19 has created unprecedented challenges in providing care to patients with resectable non-small cell lung carcinoma (NSCLC). Surgical management now needs to consider the risks of malignant disease progression by delaying surgery, and those of COVID-19 transmission to patients and operating room staff. The goal of our study was to describe our experience in providing both emergent and elective surgical procedures for patients with NSCLC during the COVID-19 pandemic in Israel, and to present our point of view regarding the safety of performing lung cancer surgery. METHODS: This observational cross-sectional study included all consecutive patients with NSCLC who operated at Tel Aviv Medical Center, a large university-affiliated hospital, from February 2020 through December 2020, during the COVID-19 pandemic in Israel. The patients' demographics, COVID-19 preoperative screening results, type and side of surgery, pathology results, morbidity and mortality rates, postoperative complications, including pulmonary complications management, and hospital stay were evaluated. RESULTS: Included in the study were 113 patients, 68 males (60.2%) and 45 females (39.8%), with a median age of 68.2 years (range, 41-89). Of these 113 patients, 83 (73.5%) underwent video-assisted thoracic surgeries (VATS), and 30 (26.5%) underwent thoracotomies. Fifty-five patients (48.7%) were preoperatively screened for COVID-19 and received negative results. Fifty-six postoperative complications were reported in 35 patients (30.9%). A prolonged air leak was detected in 11 patients (9.7%), atrial fibrillation in 11 patients (9.7%), empyema in 5 patients (4.4%), pneumonia in 9 patients (7.9%) and lobar atelectasis in 7 patients (6.2%). Three patients (2.7%) with postoperative pulmonary complications required mechanical ventilation, and two of them (1.6%) underwent tracheostomy. Two patients (1.6%) were postoperatively diagnosed as positive for COVID-19. CONCLUSIONS: Our data demonstrate the feasibility and efficacy of implementing precautionary strategies to ensure the safety of lung cancer patients undergoing pulmonary resection during the COVID-19 pandemic. The strategy was equally effective in protecting the surgical staff and healthcare providers, and we recommend performing lung cancer surgery during the pandemic era.

The Impact of Intraoperative Donor Blood on Packed Red Blood Cell Transfusion During Deceased Donor Liver Transplantation: A Retrospective Cohort Study.

BACKGROUND: Blood from deceased organ donors, also known as donor blood (DB), has the potential to reduce the need for packed red blood cells (PRBCs) during liver transplantation (LT). We hypothesized that DB removed during organ procurement is a viable resource that could reduce the need for PRBCs during LT. METHODS: We retrospectively examined data on LT recipients aged over 18 y who underwent a deceased donor LT. The primary aim was to compare the incidence of PRBC transfusion in LT patients who received intraoperative DB (the DB group) to those who did not (the nondonor blood [NDB] group). RESULTS: After a propensity score matching process, 175 patients received DB and 175 did not. The median (first-third quartile) volume of DB transfused was 690.0 mL (500.0-900.0), equivalent to a median of 3.1 units (2.3-4.1). More patients in the NDB group received an intraoperative PRBC transfusion than in the DB group: 74.3% (95% confidence intervals, 67.8-80.8) compared with 60% (95% confidence intervals, 52.7-67.3); P = 0.004. The median number of PRBCs transfused intraoperatively was higher in the NDB group compared with the DB group: 3 units (0-6) compared with 2 units (0-4); P = 0.004. There were no significant differences observed in the secondary outcomes. CONCLUSIONS: Use of DB removed during organ procurement and reinfused to the recipient is a viable resource for reducing the requirements for PRBCs during LT. Use of DB minimizes the exposure of the recipient to multiple donor sources.

Remote ischemic preconditioning improves tissue oxygenation in a porcine model of controlled hemorrhage without fluid resuscitation.

Remote ischemic preconditioning (RIPC) involves deliberate, brief interruptions of blood flow to increase the tolerance of distant critical organs to ischemia. This study tests the effects of limb RIPC in a porcine model of controlled hemorrhage without replacement therapy simulating an extreme field situation of delayed evacuation to definitive care. Twenty-eight pigs (47 ± 6 kg) were assigned to: (1) control, no procedure (n = 7); (2) HS = hemorrhagic shock (n = 13); and (3) RIPC + HS = remote ischemic preconditioning followed by hemorrhage (n = 8). The animals were observed for 7 h after bleeding without fluid replacement. Survival rate between animals of the RIPC + HS group and those of the HS group were similar (HS, 6 of 13[46%]-vs-RIPC + HS, 4 of 8[50%], p = 0.86 by Chi-square). Animals of the RIPC + HS group had faster recovery of mean arterial pressure and developed higher heart rates without complications. They also had less decrease in pH and bicarbonate, and the increase in lactate began later. Global oxygen delivery was higher, and tissue oxygen extraction ratio lower, in RIPC + HS animals. These improvements after RIPC in hemodynamic and metabolic status provide essential substrates for improved cellular response after hemorrhage and reduction of the likelihood of potentially catastrophic consequences of the accompanying ischemia.

Ventilating the Bearded: A Randomized Crossover Trial Comparing a Novel Bag-Valve-Guedel Adaptor to a Standard Mask.

INTRODUCTION: Emergency field ventilation using bag-valve face mask devices can be difficult to perform, especially in bearded individuals. In view of the increasing numbers of servicemen and civilians sporting a beard or moustache, the issue of finding a technical solution for ventilation in this population has gained importance. We therefore developed a novel adaptor that enables the direct connection of a bag-valve device to a Guedel-type oropharyngeal airway device thereby directly connecting the oral airway to the bag valve, eliminating the need for a face mask. The objective of this study was to compare the efficacy of the bag-valve-Guedel adaptor (BVGA) to the common face mask in healthy bearded volunteers. METHODS: This study was a randomized-by-sequence, crossover-controlled trial (NCT02768246) approved by the local IRB (0051-16-HMO). All subjects signed an informed consent before participation. Twenty-five healthy bearded men (age 28 ± 7) were recruited. After randomization, the first group (mask then BVGA, n = 12) began breathing room air through the face mask, followed by 100% O2. After washout in room air, the procedure was repeated with the BVGA. The second group (BVGA then mask, n = 13) began with the BVGA followed by the face mask. Subjects were awake and breathed spontaneously throughout the experiment. Therefore, a Guedel was not used. Physiological and respiratory parameters were monitored continuously. The primary endpoint was the presence of suspected leak as determined by end-tidal-CO2 (EtCO2 < 20 mmHg). Secondary endpoints included tidal volume and safety. RESULTS: The order of device use did not affect the results significantly (p > 0.05 by Mann-Whitney-U test); therefore, the data were pooled. There were no cases of suspected leak while breathing through the BVGA. By contrast, while breathing through a face mask, there were 8 of 25 (32%) and 5 of 25 (20%) cases of suspected leak in air and 100% O2, respectively (air: p = 0.002; 100% O2: p = 0.014 by McNemar test). No adverse events were observed. CONCLUSIONS: In bearded individuals, the BVGA provides significantly more efficient (less leak) ventilation compared to a face mask. This is also of particular importance in view of the increasing number of bearded individuals serving in the armed forces. Moreover, since effective ventilation with a mask requires experience, the relatively easy-to-apply BVGA will enable less experienced first responders to achieve higher success rates in this critical phase of treatment. Further studies are planned to evaluate the efficacy of the BVGA in the prehospital setting.