Simulated ventilation of two patients with a single ventilator in a pandemic setting.

Simultaneous ventilation of two patients may lead to hypoventilation in one patient and hyperinflation in the other patient. In a simulation of ventilation in two patients using artificial lungs, we voluntarily directed gas flow to one patient by using three-dimensional-printed Y-adapters and stenosis adapters during volume- and pressure-controlled ventilation in the first set up. We continuously modified the model using a special one-way valve on the flow-limited side and measured it in pressure-controlled ventilation with the flow sensor of the ventilator adjusted on both sides in a second and third setup. In the first setup, volume- or pressure-controlled ventilation resulted in comparable minute volumes in both lungs, even when one side was obstructed to 3 mm. In the second setup, with a 3-mm flow limitation, we had a minute ventilation of 9.4 ± 0.3 vs. 3.5 ± 0.1 L/min. In the third setup, ventilation with a 3-mm flow limitation resulted in minute ventilation of 7.2 ± 0.2 vs. 5.70 L/min at a compliance of 30 vs. 70 mL/mbar. It is possible to override the safety features of a modern intensive care ventilator and thus direct tidal volumes in different lung conditions to one lung using three-dimensional-printed flow limiters. While this ventilation setting was technically feasible in a bench model, it would be unstable, if not dangerous, in a clinical situation.

The efficacy of apneic oxygenation during intubation using a prototype of an oxygenation laryngoscope - a technical simulation.

BACKGROUND: Recently, a non-commercial oxygenation laryngoscope was able to maintain apneic oxygenation during simulated intubation efforts. Since that prototype was 3 mm wider than a standard Macintosh laryngoscope blade, the intubation performance of this device may differ from standard blades. A new prototype of an oxygenation laryngoscope was developed, consisting of a standard-size Macintosh blade and a fixed oxygen supply line to the side. Actually, it is unclear at which point of this blade the oxygen supply line should end to facilitate the best possible oxygen supply for apneic oxygenation. METHODS: In this simulation study using a standardized human airway manikin, the efficacy of apneic oxygenation by oxygen insufflation using standard and modified Macintosh blades was compared: a standard Macintosh blade without oxygen supply line as control, one with an additional oxygen supply line ending proximal near the handle, one with the line ending at the middle of the blade, and one with the line ending near the tip. A preoxygenated test lung was connected to an oximeter with a flow rate of 200ml/min, simulating oxygen consumption of a male adult, and to the trachea of an anatomically correctly shaped airway manikin. Apneic oxygenation was performed and oxygen content was measured over a 20-minutes observation period. Experiments were repeated five times for each laryngoscope blade. RESULTS: Oxygen percentage in the test lung dropped from 100 ± 0% at the start of the experiment to 53 ± 1.5% in the room air control group (p < 0.001 compared to all other groups), and to 74 ± 2.5% in the proximal oxygen line group, whereas oxygen percentage remained at 100% in both the medium and distal oxygen line groups (p = 1 between these groups; p < 0.001 between all other groups). CONCLUSIONS: In this simulation study with a preoxygenated airway manikin, the use of a modified Macintosh laryngoscope blade with oxygen line attached at the tip or at the middle were able to maintain apneic oxygenation without measurable drop of oxygen content over 20 min. Proximal placement of the oxygen supply line still showed an advantage against room air, however it did not completely prevent room air from entering the airway. TRIAL REGISTRATION: Not applicable.

Oral transmucosal fentanyl citrate analgesia in prehospital trauma care: an observational cohort study.

BACKGROUND: Pain is one of the major prehospital symptoms in trauma patients and requires prompt management. Recent studies have reported insufficient analgesia after prehospital treatment in up to 43% of trauma patients, leaving significant room for improvement. Good evidence exists for prehospital use of oral transmucosal fentanyl citrate (OTFC) in the military setting. We hypothesized that the use of OTFC for trauma patients in remote and challenging environment is feasible, efficient, safe, and might be an alternative to nasal and intravenous applications. METHODS: This observational cohort study examined 177 patients who were treated with oral transmucosal fentanyl citrate by EMS providers in three ski and bike resorts in Switzerland. All EMS providers had previously been trained in administration of the drug and handling of potential adverse events. RESULTS: OTFC caused a statistically significant and clinically relevant decrease in the level of pain by a median of 3 (IQR 2 to 4) in NRS units (P < 0.0001). Multiple linear regression analysis showed a significant absolute reduction in pain, with no differences in all age groups and between genders. No major adverse events were observed. CONCLUSIONS: Prehospital administration of OTFC is safe, easy, and efficient for extrication and transport across all age groups, gender, and types of injuries in alpine environments. Side effects were few and mild. This could provide a valuable alternative in trauma patients with severe pain, without the delay of inserting an intravenous line, especially in remote areas, where fast action and easy administration are important.

Influence of positive end-expiratory pressure on arterial blood pressure in mechanically ventilated trauma patients in the field: a retrospective cohort study.

Ventilation with positive end-expiratory pressure (PEEP) may result in decreased venous return to the heart and therefore decrease cardiac output. We evaluated the influence of PEEP ventilation on arterial blood pressure in the field in 296 posttraumatic intubated patients being treated by a helicopter emergency medical service in a retrospective cohort study. Initial systolic blood pressure on the scene, upon hospital admission and their mean difference were compared between patients being ventilated with no/low PEEP (0-0.3 kPa) and moderate PEEP (0.3-1 kPa). In a subgroup analysis of initially hemodynamic unstable patients (systolic blood pressure < 80 mmHg), systolic blood pressure was compared between patients being ventilated with no/low or moderate PEEP Further, the mean difference between initial systolic blood pressure and upon hospital admission was correlated with the chosen PEEP. Systolic arterial blood pressure of patients being ventilated with no/low PEEP improved from 105 ± 36 mmHg to 112 ± 38 mmHg, and that of patients being ventilated with moderate PEEP improved from 105 ± 38 mmHg to 119 ± 27 mmHg. In initially unstable patients being ventilated with no/low PEEP systolic blood pressure improved from initially 55 ± 36 mmHg to 78 ± 30 mmHg upon hospital admission, and in those being ventilated with moderate PEEP, the systolic blood pressure improved from 43 ± 38 mmHg to 91 ± 27 mmHg. There was no significant correlation between the chosen PEEP and the mean difference of systolic blood pressure (Pearson's correlation, r = 0.07, P = 0.17). Ventilation with moderate PEEP has no adverse effect on arterial systolic blood pressure in this cohort of trauma patients requiring mechanical ventilation. Initially unstable patients being ventilated with moderate PEEP tend to be hemodynamically more stable.

Identification of the Optimal Position of a Nasal Oxygen Cannula for Apneic Oxygenation: A Technical Simulation.

Background: In a cannot-ventilate-cannot-intubate situation, careful preoxygenation with high FiO2 allowing subsequent apneic oxygenation can be life-saving. The best position for an oxygen supply line within the human airway at which oxygen insufflation is more effective than standard preoxygenation with a face mask is unknown. Methods: In this experimental study, we compared the effectiveness of preoxygenation by placing an oxygen cannula at the nose entrance, through the nose at the soft palatine, or at the base of the tongue; as a control we used ambient air. We connected a fully preoxygenated test lung on one side to an oximeter with a flow rate of 200 mL/min simulating the oxygen consumption of a normal adult on the other side of the trachea of an anatomically correctly shaped airway manikin over a 20 min observation period five times for each cannula placement in a random order. Results: The oxygen percentage in the test lung dropped from 100% in all groups to 53 ± 1% in the ambient air control group, to 87 ± 2% in the nasal cannula group, and to 96 ± 2% in the soft palatine group; it remained at 99 ± 1% in the base of the tongue group (p = 0.003 for the soft palatine vs. base of the tongue and p < 0.001 for all other groups). Conclusions: When simulating apneic oxygenation in a preoxygenated manikin, oxygen insufflation at the base of the tongue kept the oxygen percentage at baseline values of 99%, demonstrating a complete block of ambient air flowing into the airway of the manikin. Oxygen insufflation at the soft palatine or insufflation via a nasal cannula were less effective regarding this effect.

Stability of Drugs Stored in Helicopters for Use by Emergency Medical Services: A Prospective Observational Study.

STUDY OBJECTIVE: Drugs stored in rescue helicopters may be subject to extreme environmental conditions. The aim of this study was to measure whether drugs stored under the real-life conditions of a Swiss helicopter emergency medical service (HEMS) would retain their potency over the course of 1 year. METHODS: A prospective, longitudinal study measuring the temperature exposure and concentration of drugs stored on 2 rescue helicopters in Switzerland over 1 year. The study drugs included epinephrine, norepinephrine, amiodarone, midazolam, fentanyl, naloxone, rocuronium, etomidate, and ketamine. Temperatures were measured inside the medication storage bags and the crew cabins at 10-minute intervals. Drug stability was measured on a monthly basis over the course of 12 months using high-performance liquid chromatography. The medications were considered stable at a minimum remaining drug concentration of 90% of the label claim. RESULTS: Temperatures ranged from -1.2 °C to 38.1 °C (29.84 °F to 100.58 °F) inside the drug storage bags. Of all the temperature measurements inside the drug storage bags, 37% lay outside the recommended storage conditions. All drugs maintained a concentration above 90% of the label claim. The observation periods for rocuronium and etomidate were shortened to 7 months because of a supply shortage of reference samples. CONCLUSION: Drugs stored under the real-life conditions of Swiss HEMS are subjected to temperatures outside the manufacturer's approved storage requirements. Despite this, all drugs stored under these conditions remained stable throughout our study. Real-life stability testing could be a way to extend drug exchange intervals.

Airway management in a Helicopter Emergency Medical Service (HEMS): a retrospective observational study of 365 out-of-hospital intubations.

BACKGROUND: Airway management is a key skill in any helicopter emergency medical service (HEMS). Intubation is successful less often than in the hospital, and alternative forms of airway management are more often needed. METHODS: Retrospective observational cohort study in an anaesthesiologist-staffed HEMS in Switzerland. Patient charts were analysed for all calls to the scene (n = 9,035) taking place between June 2016 and May 2017 (12 months). The primary outcome parameter was intubation success rate. Secondary parameters included the number of alternative techniques that eventually secured the airway, and comparison of patients with and without difficulties in airway management. RESULTS: A total of 365 patients receiving invasive ventilatory support were identified. Difficulties in airway management occurred in 26 patients (7.1%). Severe traumatic brain injury was the most common indication for out-of-hospital Intubation (n = 130, 36%). Airway management was performed by 129 different Rega physicians and 47 different Rega paramedics. Paramedics were involved in out-of-hospital airway manoeuvres significantly more often than physicians: median 7 (IQR 4 to 9) versus 2 (IQR 1 to 4), p < 0.001. CONCLUSION: Despite high overall success rates for endotracheal intubation in the physician-staffed service, individual physicians get only limited real-life experience with advanced airway management in the field. This highlights the importance of solid basic competence in a discipline such as anaesthesiology.

Nature Interest Scale - Development and Evaluation of a Measurement Instrument for Individual Interest in Nature.

Interest is an important factor for successful learning that has been the subject of intensive research for decades. Although interest in nature is of great importance for environmental education, to date there is no valid and reliable measurement tool. Therefore, the purpose of this study was to develop and test a scale for interest in nature, the Nature Interest Scale (NIS). In study 1, nine items were selected based on the three dimensions of the psychological interest construct to represent interest in nature. The factor structure of this new measurement instrument, was tested using confirmatory factor analyses. The results show that the instrument represents the three dimensions of the interest construct well. In study 2 the validity (discriminant and convergent validity) as well as the reliability (internal consistency, composite reliability, test-retest reliability) of the NIS were demonstrated. In study 3, the applicability of the NIS was tested with a different target group, students with learning disabilities. The results of this factor analysis also confirm the factor structure of the scale. Thus, this study provides a valid and reliable measurement tool for individual interest in nature that can be used for future research.

Incidence and challenges of helicopter emergency medical service (HEMS) rescue missions with helicopter hoist operations: analysis of 11,228 daytime and nighttime missions in Switzerland.

OBJECTIVE: We aimed to investigate the medical characteristics of helicopter hoist operations (HHO) in HEMS missions. METHODS: We designed a retrospective study evaluating all HHO and other human external cargo (HEC) missions performed by Swiss Air-Rescue (Rega) between January 1, 2010, and December 31, 2019. RESULTS: During the study period, 9,963 (88.7 %) HEMS missions with HHO and HEC were conducted during the day, and 1,265 (11.3 %) at night. Of the victims with time-critical injuries (NACA ≥ 4), 21.1 % (n = 400) reached the hospital within 60 min during the day, and 9.1 % (n = 18) at night. Nighttime missions, a trauma diagnosis, intubation on-site, and NACA Score ≥ 4 were independently and highly significantly associated with longer mission times (p < 0.001). The greatest proportion of patients who needed hoist or HEC operations in the course of the HEMS mission during the daytime sustained moderate injuries (NACA 3, n = 3,731, 37.5 %) while practicing recreational activities (n = 5,492, 55.1 %). In daytime HHO missions, the most common medical interventions performed were insertion of a peripheral intravenous access (n = 3,857, 38.7 %) and administration of analgesia (n = 3,121, 31.3 %). CONCLUSIONS: Nearly 20 % of patients who needed to be evacuated by a hoist were severely injured, and complex and lifesaving medical interventions were necessary before the HHO procedure. Therefore, only adequately trained and experienced medical crew members should accompany HHO missions.

Nasal nalbuphine analgesia in prehospital trauma managed by first-responder personnel on ski slopes in Switzerland: an observational cohort study.

BACKGROUND: Pain is one of the major symptoms complained about by patients in the prehospital setting, especially in the case of trauma. When there is mountainous topography, as in Switzerland, there may be a time delay between injury and arrival of professional rescuers, in particular on ski slopes. Administration of a safe opioid by first responders may improve overall treatment. We therefore assessed administration of nasal nalbuphine as an analgesic treatment for trauma patients in Switzerland. METHODS: This observational cohort study examined 267 patients who were treated with nasal nalbuphine by first responders in six ski resorts in Switzerland. All first responders were instructed to begin treatment by assessing the feasibility of using nalbuphine to treat pain in the patient. A treatment algorithm was developed and distributed to assure that nalbuphine was only administered following a strict protocol. Data regarding pain scores and pain reduction after administration of nalbuphine were collected on-site. Refills were handed out to the first responders with the return of each completed questionnaire. RESULTS: Nalbuphine provided effective pain relief, with the median level of pain on the numeric rating scale for pain reduced by 3 units on average, from 8 points (p < 0.001). The multivariate regression model showed that pain reduction was more pronounced in patients with higher initial pain levels. Nalbuphine was more effective in adolsecents than in patients aged 20 to 60 years (p = 0.006). No major side effects were observed. CONCLUSION: Nasal administration of nalbuphine by first responders is a presumably safe and effective noninvasive pain management strategy for acutely injured patients in the prehospital setting. This may be an alternative, especially in the case of severe pain and prolonged time between arrival of the first responders and arrival of EMS/HEMS personnel on scene.

Mechanical chest compression devices in the helicopter emergency medical service in Switzerland.

BACKGROUND: Over the past years, several emergency medical service providers have introduced mechanical chest compression devices (MCDs) in their protocols for cardiopulmonary resuscitation (CPR). Especially in helicopter emergency medical systems (HEMS), which have limitations regarding loading weight and space and typically operate in rural and remote areas, whether MCDs have benefits for patients is still unknown. The aim of this study was to evaluate the use of MCDs in a large Swiss HEMS system. MATERIALS AND METHODS: We conducted a retrospective observational study of all HEMS missions of Swiss Air rescue Rega between January 2014 and June 2016 with the use of an MCD (Autopulse®). Details of MCD use and patient outcome are reported from the medical operation journals and the hospitals' discharge letters. RESULTS: MCDs were used in 626 HEMS missions, and 590 patients (94%) could be included. 478 (81%) were primary missions and 112 (19%) were interhospital transfers. Forty-nine of the patients in primary missions were loaded under ongoing CPR with MCDs. Of the patients loaded after return of spontaneous circulation (ROSC), 20 (7%) experienced a second CA during the flight. In interhospital transfers, 102 (91%) only needed standby use of the MCD. Five (5%) patients were loaded into the helicopter with ongoing CPR. Five (5%) patients went into CA during flight and the MCD had to be activated. A shockable cardiac arrhythmia was the only factor significantly associated with better survival in resuscitation missions using MCD (OR 0.176, 95% confidence interval 0.084 to 0.372, p < 0.001). CONCLUSION: We conclude that equipping HEMS with MCDs may be beneficial, with non-trauma patients potentially benefitting more than trauma patients.

Temperature loss by ventilation in a calorimetric bench model.

In intensive care medicine heat moisture exchangers are standard tools to warm and humidify ventilation gases in order to prevent temperature loss of patients or airway epithelia damage. Despite being at risk of hypothermia especially after trauma, intubated emergency medicine patients are often ventilated with dry and in winter probably cold ventilation gases. We tried to assess the amount of temperature-loss due to ventilation with cold, dry medical oxygen in comparison to ventilation with warm and humidified oxygen. We ventilated a 50-kg water-dummy representing the calorimetric capacity of a 60-kg patient over a period of 2 hours (tidal volume 6.6 mL/kg = 400 mL; respiratory rate 13/min). Our formal null-hypothesis was that there would be no differences in temperature loss in a 50 kg water-dummy between ventilation with dry oxygen at 10°C vs. ventilation with humidified oxygen at 43°C. After 2 hours the temperature in the water-dummy using cold and dry oxygen was 29.7 ± 0.1°C compared to 30.4 ± 0.1°C using warm and humidified oxygen. This difference in cooling rates between both ventilation attempts of 0.7 ± 0.1°C after 2 hours represents an increased cooling rate of ~0.35°C per hour. Ventilation with cool, dry oxygen using an automated transport ventilator resulted in a 0.35°C faster cooling rate per hour than ventilation with warm humidified oxygen in a bench model simulating calorimetric features of a 60-kg human body.

Safer employment of nitrous oxide in anesthesia machines-a technical simulation.

Several incidents of anesthesia-attributed mortality in the past were caused by misconnection of gas pipelines resulting in ventilation with pure nitrous oxide. A simple safety feature may be to "mark" nitrous oxide with a lower pressure than oxygen and room air within the hospital's gas pipeline system. Then, any misconnection of gas pipelines could be detected by pressure differences with a manometer in the anesthesia machine. To check technical suitability, we tested maximum achievable nitrous oxide flows of an anesthesia machine at different pressures in the nitrous oxide supply line. Using decreased pressures for nitrous oxide compared to oxygen did not result in decreased nitrous oxide flows, as long as pressure in the nitrous oxide supply line was >1500 hPa. A concept of different pressures for nitrous oxide and oxygen could be used to technically differentiate between those two gases, and to avoid potentially fatal misconnections.

Blood glucose concentrations in prehospital trauma patients with traumatic shock: A retrospective analysis.

BACKGROUND: Deranged glucose metabolism after moderate to severe trauma with either high or low concentrations of blood glucose is associated with poorer outcome. Data on prehospital blood glucose concentrations and trauma are scarce. OBJECTIVES: The primary aim was to describe the relationship between traumatic shock and prehospital blood glucose concentrations. The secondary aim was to determine the additional predictive value of prehospital blood glucose concentration for traumatic shock when compared with vital parameters alone. DESIGN: Retrospective analysis of the predefined, observational database of a nationwide Helicopter Emergency Medical Service (34 bases). SETTING: Emergency trauma patients treated by Helicopter Emergency Medical Service between 2005 and 2013 were investigated. PATIENTS: All adult trauma patients (≥18 years) with recorded blood glucose concentrations were enrolled. OUTCOMES: Primary outcome: upper and lower thresholds of blood glucose concentration more commonly associated with traumatic shock. Secondary outcome: additional predictive value of prehospital blood glucose concentrations when compared with vital parameters alone. RESULTS: Of 51 936 trauma patients, 20 177 were included. In total, 220 (1.1%) patients died on scene. Hypoglycaemia (blood glucose concentration 2.8 mmol l or less) was observed in 132 (0.7%) patients, hyperglycaemia (blood glucose concentration exceeding 15 mmol l) was observed in 265 patients (1.3%). Blood glucose concentrations more than 10 mmol l (n = 1308 (6.5%)) and 2.8 mmol l or less were more common in patients with traumatic shock (P < 0.0001). The Youden index for traumatic shock ((sensitivity + specificity) - 1) was highest when blood glucose concentration was 3.35 mmol l (P < 0.001) for patients with low blood glucose concentrations and 7.75 mmol l (P < 0.001) for those with high blood glucose concentrations. In logistic regression analysis of patients with spontaneous circulation on scene, prehospital blood glucose concentrations (together with common vital parameters: Glasgow Coma Scale, heart rate, blood pressure, breathing frequency) significantly improved the prediction of traumatic shock in comparison with prediction by common vital parameters alone (P < 0.0001). CONCLUSION: In adult trauma patients, low and high blood glucose concentrations were more common in patients with traumatic shock. Prehospital blood glucose concentration measurements in addition to common vital parameters may help identify patients at risk of traumatic shock.

2015 revised Utstein-style recommended guidelines for uniform reporting of data from drowning-related resuscitation: An ILCOR advisory statement.

BACKGROUND: Utstein-style guidelines use an established consensus process, endorsed by the international resuscitation community, to facilitate and structure resuscitation research and publication. The first "Guidelines for Uniform Reporting of Data From Drowning" were published over a decade ago. During the intervening years, resuscitation science has advanced considerably, thus making revision of the guidelines timely. In particular, measurement of cardiopulmonary resuscitation elements and neurological outcomes reporting have advanced substantially. The purpose of this report is to provide updated guidelines for reporting data from studies of resuscitation from drowning. METHODS: An international group with scientific expertise in the fields of drowning research, resuscitation research, emergency medical services, public health, and development of guidelines met in Potsdam, Germany, to determine the data that should be reported in scientific articles on the subject of resuscitation from drowning. At the Utstein-style meeting, participants discussed data elements in detail, defined the data, determined data priority, and decided how data should be reported, including scoring methods and category details. RESULTS: The template for reporting data from drowning research was revised extensively, with new emphasis on measurement of quality of resuscitation, neurological outcomes, and deletion of data that have proved to be less relevant or difficult to capture. CONCLUSIONS: The report describes the consensus process, rationale for selecting data elements to be reported, definitions and priority of data, and scoring methods. These guidelines are intended to improve the clarity of scientific communication and the comparability of scientific investigations.