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.

[Medical emergencies during running events]. / Notfallmedizinische Aspekte bei Laufveranstaltungen.

Background: The number of short- and long-distance running events in Germany is increasing. Running as a popular sport is practiced by a large number of people of different ages, risk groups, and degrees of professionalism, which results in a wide range of medical emergencies. Objective: The present article elucidates incidence, pathophysiology and therapy of relevant emergencies during running events. Aim was the optimization of work processes of emergency personnel. Materials and methods: A literature search was conducted in PubMed. Results: Exercise-associated muscle cramps, gastrointestinal symptoms, collapse, compartment syndrome, and tendinopathy are common clinical manifestations. Cardiac arrest and sudden cardiac death are rare events. Consciousness and seizures are major complications. Disseminated intravascular coagulation, exercise-associated hyponatremia, heat stroke, rhabdomyolysis, and thromboembolism are associated with high morbidity and mortality. Substances increasing pain resilience as well as performance-enhancing substances are popular among amateur and professional runners and are associated with a high incidence of side effects. Conclusion: General symptoms including vomiting, fever, collapse, muscle-pain, nausea and weakness are the leading symptoms during running events. A careful anamnesis is important for targeted clinical therapy. Symptom control is the main task. Fluid management the most challenging task for healthcare providers in the prehospital setting.

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.

Shedding of the Endothelial Glycocalyx Independent of Systemic Tryptase Release during Oncologic Oral Surgery: An Observational Study.

The endothelial glycocalyx and endothelial surface layer are crucial for several functions of the vasculature. Damage to the glycocalyx ("shedding") occurs during diverse clinical conditions, including major surgery. Mast cell tryptase has been proposed as one possible "sheddase". During oncologic oral surgery, glycocalyx shedding could be detrimental due to loss of vascular barrier function and consequent oedema in the musculocutaneous flap graft. Concentrations of the glycocalyx components heparan sulphate and syndecan-1, as well as of tryptase in blood serum before and after surgery, were measured in 16 patients undergoing oncologic oral surgery. Secondary measures were the concentrations of these substances on postoperative days 1 and 2. Heparan sulphate rose from 692 (median, interquartile range: 535-845) to 810 (638-963) ng/mL during surgery. Syndecan-1 increased from 35 (22-77) ng/mL to 138 (71-192) ng/mL. Tryptase remained virtually unchanged with 4.2 (3-5.6) before and 4.2 (2.5-5.5) ng/mL after surgery. Concentrations of heparan sulphate and syndecan-1 in serum increased during surgery, indicating glycocalyx shedding. Tryptase concentration remained equal, suggesting other sheddases than systemic tryptase release to be responsible for damage to the glycocalyx. Investigating strategies to protect the glycocalyx during oncologic oral surgery might hold potential to improve flap viability and patient outcome.

Airway Management during Massive Gastric Regurgitation Using VieScope or Macintosh Laryngoscope-A Randomized, Controlled Simulation Trial.

In this model of massive gastric aspiration, we compared two different laryngoscopes (VieScope and Macintosh) in a randomized, controlled simulation study. The primary endpoint was time to intubation; the secondary endpoints were intubation success (i.e., tracheal tube position) and amount of pulmonary aspiration. Thirty-four anesthetists performed endotracheal intubation using VieScope and Macintosh laryngoscopy in a randomized order on an airway manikin simulating massive regurgitation of gastric fluid. The primary endpoint "time until intubation" could be achieved significantly faster (mean −12.4 s [95% confidence intervals (CI) −19.7 s; −7.3 s]) with Macintosh compared to VieScope (p < 0.001). Concerning "correct tube position", no statistical difference was found between the devices (p = 1.0). The mean time to first ventilation was −11.1 s [95% CI −18.3 s; −5.3 s] when using Macintosh (p = 0.001). The mean volume of aspirated gastric fluid was lower in the Macintosh group: −90.0 mL [95% CI −235.0 mL; −27.5 mL] (p = 0.011). Data from this simulation study suggest that in a model of massive gastric regurgitation, airway management can be achieved faster and with less gastric aspiration when using a Macintosh laryngoscope compared to a VieScope laryngoscope.

Comparing suction rates of novel DuCanto catheter against Yankauer and standard suction catheter using liquids of different viscosity-a technical simulation.

PURPOSE: Aspiration is a feared complication that may occur during airway management, and can significantly contribute to morbidity and mortality. Availability of a suctioning device with a suction catheter capable of clearing the airway is mandatory for airway management. However, suction performance may be significantly different amongst different suction catheters. The aim of this study was to compare suction rates of a standard 14 Ch suction catheter (SC), a Yankauer catheter (Y) and a DuCanto catheter (DC) using 4 fluids with different viscosity. METHODS: In this simulation trial, 4 preparations with standardized viscosity were prepared using a Xanthane-based medical fluid thickener. Lowest viscosity was achieved using tap water without thickener, syrup-like viscosity was achieved by adding 10 g per liter tap water, honey-like viscosity was achieved by adding 20 g per liter, and a pudding-like viscosity was achieved by adding 30 g of thickening powder per liter tap water. Each preparation was suctioned for 15 s with the three different suctioning devices. Measurements were repeated four times. The amount of removed preparation by suctioning was measured using a tared scale. RESULTS: Suction rates for water were 580 ± 34 mg for SC, 888 ± 5 mg for Y and 1087 ± 15 for DC; for syrup-like viscosity it was 383 ± 34(SC) vs. 661 ± 64(Y) vs. 935 ± 42(DC); for honey-like viscosity it was 191 ± 21(SC) vs. 426 ± 34(Y) vs. 590 ± 68(DC); and for pudding-like viscosity 74 ± 13(SC) vs. 164 ± 6(Y) vs. 211 ± 8(DC). CONCLUSION: Suctioning liquids of different viscosity, the new DuCanto catheter was more effective than the Yankauer catheter that was more effective than a standard suctioning catheter. The relative superiority of the DuCanto was highest in fluids with high viscosity.

A special oropharyngeal oxygenation device to facilitate apneic oxygenation in comparison to high flow oxygenation devices.

Oxygen application and apneic oxygenation may reduce the risk of hypoxemia due to apnea during awake fiberoptic intubation or failed endotracheal intubation. High flow devices are recommended, but their effect compared to moderate deep oropharyngeal oxygen application is unknown. Designed as an experimental manikin trial, we made a comparison between oxygen application via nasal prongs at 10 L/min (control group), applying oxygen via oropharyngeal oxygenation device (at 10 L/min), oxygen application via high flow nasal oxygen with 20 L/min and 90% oxygen (20 L/90% group), oxygen application via high flow nasal oxygen with 60 L/min and 45% oxygen (60 L/45% group), and oxygen application via sealed face mask with a special adapter to allow for fiberoptic entering of the airway. We preoxygenated the lung of a manikin and measured the decrease in oxygen level during the following 20 minutes for each way of oxygen application. Oxygen levels fell from 97 ± 1% at baseline to 75 ± 1% in control group, and to 86 ± 1% in oropharyngeal oxygenation device group. In the high flow nasal oxygen group, oxygen level dropped to 72 ± 1% in the 20 L/90% group and to 44 ± 1% in the 60 L/45% group. Oxygen level remained at 98 ± 0% in the face mask group. In conclusion, in this manikin simulation study of apneic oxygenation, oxygen insufflation using a sealed face mask kept oxygen levels in the test lung at 98% over 20 minutes, oral oxygenation device led to oxygen levels at 86%, whereas all other methods resulted in the decrease of oxygen levels below 75%.

Intubation using VieScope vs. Video laryngoscopy in full personal protective equipment - a randomized, controlled simulation trial.

BACKGROUND: VieScope is a new type of laryngoscope, with a straight, transparent and illuminated blade, allowing for direct line of sight towards the larynx. In addition, VieScope is disposed of after single patient use, which can avoid cross-contaminations of contagious material. This has gained importance especially when treating patients with highly contagious infectious diseases, such as during the SARS-CoV2 pandemic. In this context, VieScope has not been evaluated yet in a clinical study. MATERIAL AND METHODS: This study compared intubation with VieScope to video-laryngoscopy (GlideScope) in normal and difficult airway in a standardized airway manikin in a randomized controlled simulation trial. Thirty-five medical specialists were asked to perform endotracheal intubation in full personal protective equipment (PPE). Primary endpoint was correct tube position. First-pass rate (i.e., success rate at the first attempt), time until intubation and time until first correct ventilation were registered as secondary endpoints. RESULTS: For correct tracheal tube placement, there was no significant difference between VieScope and GlideScope in normal and difficult airway conditions. VieScope had over 91% fist-pass success rate in normal airway setting. VieScope had a comparable success rate to GlideScope in difficult airway, but had a significantly longer time until intubation and time until ventilation. CONCLUSION: VieScope and GlideScope had high success rates in normal as well as in difficult airway. There was no unrecognized esophageal intubation in either group. Overall time for intubation was longer in the VieScope group, though in an acceptable range given in literature. Results from this simulation study suggest that VieScope may be an acceptable alternative for tracheal intubation in full PPE. TRIAL REGISTRATION: The study was registered at the German Clinical Trials Register www.drks.de (Registration date: 09/11/2020; TrialID: DRKS00023406 ).

Comparison of the novel VieScope with conventional and video laryngoscope in a difficult airway scenario - a randomized, controlled simulation trial.

BACKGROUND: Endotracheal intubation continues to be the gold standard for securing the airway in emergency situations. Difficult intubation is still a dreadful situation when securing the airway. OBJECTIVE: To compare VieScope with Glidescope and conventional Macintosh laryngoscopy (MAC) in a simulated difficult airway situation. METHODS: In this randomized controlled simulation trial, 35 anesthesiologists performed endotracheal intubation using VieScope, GlideScope and MAC in a randomized order on a certified airway manikin with difficult airway. RESULTS: For the primary endpoint of correct tube position, no statistical difference was found (p = 0.137). Time until intubation for GlideScope (27.5 ± 20.3 s) and MAC (20.8 ± 8.1 s) were shorter compared to the VieScope (36.3 ± 10.1 s). Time to first ventilation, GlideScope (39.3 ± 21.6 s) and MAC (31.9 ± 9.5 s) were also shorter compared to the VieScope (46.5 ± 12.4 s). There was no difference shown between handling time for VieScope (20.7 ± 7.0 s) and time until intubation with GlideScope or MAC. Participants stated a better Cormack & Lehane Score with VieScope, compared to direct laryngoscopy. CONCLUSION: Rate of correct tracheal tube position was comparable between the three devices. Time to intubation and ventilation were shorter with MAC and Glidescope compared to VieScope. It did however show a comparable handling time to video laryngoscopy and MAC. It also did show a better visualization of the airway in the Cormack & Lehane Score compared to MAC. TRIAL REGISTRATION: The study was registered at the German Clinical Trials Register www.drks.de (Identifier: DRKS00024968 ) on March 31st 2021.

Positron Emission Tomography Imaging of Long-Term Expression of the 18 kDa Translocator Protein After Sudden Cardiac Arrest in Rats.

BACKGROUND: Knowledge about the neuroinflammatory state during months after sudden cardiac arrest is scarce. Neuroinflammation is mediated by cells that express the 18 kDa translocator protein (TSPO). We determined the time course of TSPO-expressing cells in a rat model of sudden cardiac arrest using longitudinal in vivo positron emission tomography (PET) imaging with the TSPO-specific tracer [18F]DAA1106 over a period of 6 months. METHODS: Five male Sprague Dawley rats were resuscitated from 6 min sudden cardiac arrest due to ventricular fibrillation, three animals served as shams. PET measurements were performed on day 5, 8, 14, 90, and 180 after intervention. Magnetic resonance imaging was performed on day 140. Imaging was preceded by Barnes Maze spatial memory testing on day 3, 13, 90, and 180. Specificity of [18F]DAA1106 binding was confirmed by Iba-1 immunohistochemistry. RESULTS: [18F]DAA1106 accumulated bilaterally in the dorsal hippocampus of all sudden cardiac arrest animals on all measured time points. Immunohistochemistry confirmed Iba-1 expressing cells in the hippocampal CA1 region. The number of Iba-1-immunoreactive objects per mm2 was significantly correlated with [18F]DAA1106 uptake. Additionally, two of the five sudden cardiac arrest rats showed bilateral TSPO-expression in the striatum that persisted until day 180. In Barnes Maze, the relative time spent in the target quadrant negatively correlates with dorsal hippocampal [18F]DAA1106 uptake on day 14 and 180. CONCLUSIONS: After sudden cardiac arrest, TSPO remains expressed over the long-term. Sustainable treatment options for neuroinflammation may be considered to improve cognitive functions after sudden cardiac arrest.

Apneic laryngeal oxygenation during elective fiberoptic intubation - a technical simulation.

BACKGROUND: Sedation during elective fiberoptic intubation for difficult airway can cause respiratory depression, apnea and periods of desaturation. During apneic episodes, hypoxemia can be prevented by insufflation of oxygen in the deep laryngeal space. The aim of this study was to evaluate an oropharyngeal oxygenation device (OOD) designed for deep laryngeal insufflation during fiberoptic intubation. METHODS: The OOD is split in the front to form a path for the bronchoscope. An external lumen delivers oxygen in the deep laryngeal space. In this experimental study, air application (as control group), oxygen application via nasal prongs, oxygen application via the OOD, and oxygen application via the working channel of a bronchoscope were compared in a technical simulation. In a preoxygenated test lung of a manikin, decrease of the oxygen saturation was measured over 20 min for each method. RESULTS: Oxygen saturation in the test lung dropped from 97 ± 1% (baseline in all groups) to 58 ± 3% in the control-group (p < 0.001 compared to all other groups) and to 78 ± 1% in the nasal prong group (p < 0.001 compared to all other groups). Oxygen saturation remained at 95 ± 2% in both the OOD group and the bronchoscopy group (p = 0.451 between those two groups). CONCLUSION: Simulating apneic laryngeal oxygenation in a preoxygenated manikin, both oxygen insufflation via the OOD and the bronchoscope kept oxygen saturation in the test lung at 95% over 20 min. Both methods significantly were more effective than oxygen insufflation via nasal prongs.

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.

Esophageal Heat Exchanger Versus Water-Circulating Cooling Blanket for Targeted Temperature Management.

To date, the optimal cooling device for targeted temperature management (TTM) remains unclear. Water-circulating cooling blankets are broadly available and quickly applied but reveal inaccuracy during maintenance and rewarming period. Recently, esophageal heat exchangers (EHEs) have been shown to be easily inserted, revealed effective cooling rates (0.26-1.12°C/h), acceptable deviations from target core temperature (<0.5°C), and rewarming rates between 0.2 and 0.4°C/h. The aim of this study was to compare cooling rates, accuracy during maintenance, and rewarming period as well as side effects of EHEs with water-circulating cooling blankets in a porcine TTM model. Mean core temperature of domestic pigs (n = 16) weighing 83.2 ± 3.6 kg was decreased to a target core temperature of 33°C by either using EHEs or water-circulating cooling blankets. After 8 hours of maintenance, rewarming was started at a goal rate of 0.25°C/h. Mean cooling rates were 1.3 ± 0.1°C/h (EHE) and 3.2 ± 0.5°C/h (blanket, p < 0.0002). Mean difference to target core temperature during maintenance ranged between ±1°C. Mean rewarming rates were 0.21 ± 0.01°C/h (EHE) and 0.22 ± 0.02°C/h (blanket, n.s.). There were no differences with regard to side effects such as brady- or tachycardia, hypo- or hyperkalemia, hypo- or hyperglycemia, hypotension, shivering, or esophageal tissue damage. Target temperature can be achieved faster by water-circulating cooling blankets. EHEs and water-circulating cooling blankets were demonstrated to be reliable and safe cooling devices in a prolonged porcine TTM model with more variability in EHE group.

Incidence of peri-operative paediatric cardiac arrest and the influence of a specialised paediatric anaesthesia team: Retrospective cohort study.

BACKGROUND: Peri-operative critical events are still a major problem in paediatric anaesthesia care. Access to more experienced healthcare teams might reduce the adverse event rate and improve outcomes. OBJECTIVE: The current study analysed incidences of peri-operative paediatric cardiac arrest before and after implementation of a specialised paediatric anaesthesia team and training programme. DESIGN: Retrospective cohort study with before-and-after analysis. SETTING: Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Cologne, Germany. PATIENTS: A total of 36 243 paediatric anaesthetics (0 to 18 years) were administered between 2008 and 2016. INTERVENTION: Implementation of a specialised paediatric anaesthesia team and training programme occurred in 2014 This included hands-on supervised training in all fields of paediatric anaesthesia, double staffing for critical paediatric cases and a 24/7 emergency team. A logistic regression analysis with risk factors (age, ASA physical status, emergency) was used to evaluate the impact of implementation of the specialised paediatric anaesthesia team. MAIN OUTCOME MEASURES: Incidences of peri-operative paediatric cardiac arrest and anaesthesia-attributable cardiac arrest before and after the intervention. RESULTS: Twelve of 25 paediatric cardiac arrests were classified as anaesthesia-attributable. The incidence of overall peri-operative paediatric cardiac arrest was 8.1/10 000 (95% CI 5.2 to 12.7) in the period 2008 to 2013 and decreased to 4.6/10 000 (95% CI 2.1 to 10.2) in 2014 to 2016. Likewise, the incidence of anaesthesia-attributable cardiac arrest was lower after 2013 [1.6/10 000 (95% CI 0.3 to 5.7) vs. 4.3/10 000 (95% CI 2.3 to 7.9)]. Using logistic regression, children anaesthetised after 2013 had nearly a 70% lower probability of anaesthesia-attributable cardiac arrest (odds ratio 0.306, 95% CI 0.067 to 1.397; P = 0.1263). For anaesthesia-attributable cardiac arrest, young age was the most contributory risk factor, whereas in overall paediatric cardiac arrest, ASA physical statuses 3 to 5 played a more important role. CONCLUSION: In this study on incidences of peri-operative paediatric cardiac arrest from a European tertiary care university hospital, implementation of a specialised paediatric anaesthesia team and training programme was associated with lower incidences of peri-operative paediatric cardiac arrest and a reduced probability of anaesthesia-attributable cardiac arrest.

Intravascular Cooling Device Versus Esophageal Heat Exchanger for Mild Therapeutic Hypothermia in an Experimental Setting.

BACKGROUND: Targeted temperature management is a standard therapy for unconscious survivors of cardiac arrest. To date, multiple cooling methods are available including invasive intravascular cooling devices (IVDs), which are widely used in the clinical setting. Recently, esophageal heat exchangers (EHEs) have been developed providing cooling via the esophagus that is located close to the aorta and inferior vena cava. The objective was to compare mean cooling rates, as well as differences, to target temperature during maintenance and the rewarming period of IVD and EHE. METHODS: The study was conducted in 16 female domestic pigs. After randomization to either IVD or EHE (n = 8/group), core body temperature was reduced to 33°C. After 24 hours of maintenance (33°C), animals were rewarmed using a target rate of 0.25°C/h for 10 hours. All cooling phases were steered by a closed-loop feedback system between the internal jugular vein and the chiller. After euthanasia, laryngeal and esophageal tissue was harvested for histopathological examination. RESULTS: Mean cooling rates (4.0°C/h ± 0.4°C/h for IVD and 2.4°C/h ± 0.3°C/h for EHE; P < .0008) and time to target temperature (85.1 ± 9.2 minutes for IVD and 142.0 ± 21.2 minutes for EHE; P = .0008) were different. Mean difference to target temperature during maintenance (0.07°C ± 0.05°C for IVD and 0.08°C ± 0.10°C for EHE; P = .496) and mean rewarming rates (0.2°C/h ± 0.1°C/h for IVD and 0.3°C/h ± 0.2°C/h for EHE; P = .226) were similar. Relevant laryngeal or esophageal tissue damage could not be detected. There were no significant differences in undesired side effects (eg, bradycardia or tachycardia, hypokalemia or hyperkalemia, hypoglycemia or hyperglycemia, hypotension, overcooling, or shivering). CONCLUSIONS: After insertion, target temperatures could be reached faster by IVD compared to EHE. Cooling performance of IVD and EHE did not significantly differ in maintaining target temperature during a targeted temperature management process and in active rewarming protocols according to intensive care unit guidelines in this experimental setting.

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.

Evaluation of small intestinal damage in a rat model of 6 Minutes cardiac arrest.

BACKGROUND: Contribution of the small intestine to systemic inflammation after cardiac arrest (CA) is poorly understood. The objective was to evaluate whether an in vivo rat model of 6 min CA is suitable to initiate intestinal ischaemia-reperfusion-injury and to evaluate histomorphological changes and inflammatory processes in the small intestinal mucosa resp. in sera. METHODS: Adult male Wistar rats were subjected to CA followed by cardio-pulmonary resuscitation. Proximal jejunum and serum was collected at 6 h, 24 h, 72 h and 7 d post return of spontaneous circulation (ROSC) and from a control group. The small intestine was evaluated histomorphologically. Cytokine concentrations were measured in jejunum lysates and sera. RESULTS: Histomorphological evaluation revealed a significant increase in mucosal damage in the jejunum at all timepoints compared to controls (p < 0.0001). In jejunal tissues, concentrations of IL-1α, IL-1ß, IL-10, and TNF-α showed significant peaks at 24 h and were 1.5- to 5.7-fold higher than concentrations at 6 h and in the controls (p < 0.05). In serum, a significant higher amount of cytokine was detected only for IL-1ß at 24 h post-ROSC compared to controls (15.78 vs. 9.76 pg/ml). CONCLUSION: CA resulted in mild small intestinal tissue damage but not in systemic inflammation. A rat model of 6 min CA is not capable to comprehensively mimic a post cardiac arrest syndrome (PCAS). Whether there is a vital influence of the intestine on the PCAS still remains unclear.

Oesophageal heat exchangers with a diameter of 11mm or 14.7mm are equally effective and safe for targeted temperature management.

BACKGROUND: Targeted temperature management (TTM) is widely used in critical care settings for conditions including hepatic encephalopathy, hypoxic ischemic encephalopathy, meningitis, myocardial infarction, paediatric cardiac arrest, spinal cord injury, traumatic brain injury, ischemic stroke and sepsis. Furthermore, TTM is a key treatment for patients after out-of-hospital cardiac-arrest (OHCA). However, the optimal cooling method, which is quick, safe and cost-effective still remains controversial. Since the oesophagus is adjacent to heart and aorta, fast heat-convection to the central blood-stream could be achieved with a minimally invasive oesophageal heat exchanger (OHE). To date, the optimal diameter of an OHE is still unknown. While larger diameters may cause thermal- or pressure-related tissue damage after long-term exposure to the oesophageal wall, smaller diameter (e.g., gastric tubes, up to 11mm) may not provide effective cooling rates. Thus, the objective of the study was to compare OHE-diameters of 11mm (OHE11) and 14.7mm (OHE14.7) and their effects on tissue and cooling capability. METHODS: Pigs were randomized to OHE11 (N = 8) or OHE14.7 (N = 8). After cooling, pigs were maintained at 33°C for 1 hour. After 10h rewarming, oesophagi were analyzed by means of histopathology. The oesophagus of four animals from a separate study that underwent exactly the identical preparation and cooling protocol described above but received a maintenance period of 24h were used as histopathological controls. RESULTS: Mean cooling rates were 2.8±0.4°C°C/h (OHE11) and 3.0±0.3°C °C/h (OHE14.7; p = 0.20). Occasional mild acute inflammatory transepithelial infiltrates were found in the cranial segment of the oesophagus in all groups including controls. Deviations from target temperature were 0.1±0.4°C (OHE11) and 0±0.1°C (OHE14.7; p = 0.91). Rewarming rates were 0.19±0.07°C °C/h (OHE11) and 0.20±0.05°C °C/h (OHE14.7; p = 0.75). CONCLUSIONS: OHE with diameters of 11 mm and 14.7 mm achieve effective cooling rates for TTM and did not cause any relevant oesophageal tissue damage. Both OHE demonstrated acceptable deviations from target temperature and allowed for an intended rewarming rate (0.25°C/h).