Efficiency of different flows for apneic oxygenation when using high flow nasal oxygen application - a technical simulation.

BACKGROUND: Preoxygenation and application of apneic oxygenation are standard to prevent patients from desaturation e.g. during emergency intubation. The time before desaturation occurs can be prolonged by applying high flow oxygen into the airway. Aim of this study was to scientifically assess the flow that is necessary to avoid nitrogen entering the airway of a manikin model during application of pure oxygen via high flow nasal oxygen. METHODS: We measured oxygen content over a 20-min observation period for each method in a preoxygenated test lung applied to a human manikin, allowing either room air entering the airway in control group, or applying pure oxygen via high flow nasal oxygen at flows of 10, 20, 40, 60 and 80 L/min via nasal cannula in the other groups. Our formal hypothesis was that there would be no difference in oxygen fraction decrease between the groups. RESULTS: Oxygen content in the test lung dropped from 97 ± 1% at baseline in all groups to 43 ± 1% in the control group (p < 0.001 compared to all other groups), to 92 ± 1% in the 10 L/min group, 92 ± 1% in the 20 L/min group, 90 ± 1% in the 40 L/min group, 89 ± 0% in the 60 L/min group and 87 ± 0% in the 80 L/min group. Apart from comparisons 10 l/ min vs. 20 L/min group (p = .715) and 10/L/min vs. 40 L/min group (p = .018), p was < 0.009 for all other comparisons. CONCLUSIONS: Simulating apneic oxygenation in a preoxygenated manikin connected to a test lung over 20 min by applying high flow nasal oxygen resulted in the highest oxygen content at a flow of 10 L/min; higher flows resulted in slightly decreased oxygen percentages in the test lung.

Oxygenation laryngoscope vs. nasal standard and nasal high flow oxygenation in a technical simulation of apnoeic oxygenation.

BACKGROUND: Failed airway management is the major contributor for anaesthesia-related morbidity and mortality. Cannot-intubate-cannot-ventilate scenarios are the most critical emergency in airway management, and belong to the worst imaginable scenarios in an anaesthetist's life. In such situations, apnoeic oxygenation might be useful to avoid hypoxaemia. Anaesthesia guidelines recommend careful preoxygenation and application of high flow oxygen in difficult intubation scenarios to prevent episodes of deoxygenation. In this study, we evaluated the decrease in oxygen concentration in a model when using different strategies of oxygenation: using a special oxygenation laryngoscope, nasal oxygen, nasal high flow oxygen, and control. METHODS: In this experimental study we compared no oxygen application as a control, standard pure oxygen application of 10 l·min- 1 via nasal cannula, high flow 90% oxygen application at 20 l·min- 1 using a special nasal high flow device, and pure oxygen application via our oxygenation laryngoscope at 10 l·min- 1. We preoxygenated a simulation lung to 97% oxygen concentration and connected this to the trachea of a manikin model simulating apnoeic oxygenation. Decrease in oxygen concentration in the simulation lung was measured continuously for 20 min. RESULTS: Oxygen concentration in the simulation lung dropped from 97 ± 1% at baseline to 40 ± 1% in the no oxygen group, to 80 ± 1% in the standard nasal oxygen group, and to 73 ± 2% in the high flow nasal oxygenation group. However, it remained at 96 ± 0% in the oxygenation laryngoscope group (p < 0.001 between all groups). CONCLUSIONS: In this technical simulation, oxygenation via oxygenation laryngoscope was more effective than standard oxygen insufflation via nasal cannula, which was more effective than nasal high flow insufflation of 90% oxygen.

[Simulation of video-assisted retrieval of foreign bodies in the airway of children by nonmedical personnel]. / Simulation einer videoassistierten Bergung von Fremdkörpern im Atemweg von Kindern durch nichtmedizinisches Personal.

BACKGROUND: Complete upper airway obstruction by a foreign body is a dramatic and acute emergency situation, and can result in rapid development of hypoxia, circulatory arrest and death. Special Magill pliers with an adjustable video optical system have been developed for airway inspection to facilitate efforts to remove foreign bodies causing obstruction of the upper airway. OBJECTIVE: To remove a simulated airway foreign body from a cardiopulmonary resuscitation (CPR) manikin, either with normal Magill pliers or with the newly designed video Magill pliers. MATERIAL AND METHODS: After a brief introduction, 81 kindergarten teachers, 51 pupils (age 10-14 years) and 52 prospective emergency physicians were asked to remove a 2â€¯× 2 "Lego" brick from the hypopharynx of a CPR manikin using either standard Magill pliers or the newly designed video Magill pliers. The formal hypothesis was that there would be no differences between the methods. Successful removal was defined as when the first removal attempt resulted in the Lego brick passing beyond the teeth of the manikin within 60s. RESULTS: The use of the video Magill pliers resulted in significantly higher success rates in removal of the simulated foreign airway body within 60 s compared to standard Magill pliers in kindergarten teachers (84% vs. 30%, p < 0.0001), pupils (84% vs. 18%, p < 0.0001) and prospective emergency physicians (92% vs. 40%, p < 0.0001). The time needed for removing the foreign airway body was significantly shorter in groups using the video Magill pliers (kindergarten teachers 29 ± 18s vs. 45 ± 19 s, pupils 29 ± 18s vs. 54 ± 14 s, and prospective emergency physicians 33 ± 18s vs. 45 ± 20 s; p < 0.0001). In an analogue points system (from 1 very simple to 10 extremely complicated), the user friendliness of the video Magill pliers was judged to be significantly higher than the standard Magill pliers (2.8 ± 1.6 vs. 7.8 ± 2.7 kindergarten teachers, 2.0 ± 1.3 vs. 7.2 ± 2.5 pupils and 3.2 ± 2.2 vs. 4.9 ± 3.1 prospective emergency physicians, p < 0.0001). Visibility of the airway foreign body was estimated to be significantly better employing the video Magill pliers compared to the standard Magill pliers (1.9 ± 1.4 vs. 9.8 ± 0.6 kindergarten teachers, pupils 1.3 ± 0.6 vs. 9.2 ± 1.6, prospective emergency physicians 2.3 ± 1.8 vs. 9.1 ± 2.3, p < 0.0001). CONCLUSION: In this study kindergarten teachers, pupils (aged 10-14 years) and prospective emergency physicians had higher success rates in less time and reported better user friendliness and visibility using video Magill pliers compared to standard Magill pliers for removing a simulated foreign body from a CPR manikin airway.

[Publications by university Departments of Anaesthesiology from Germany, Austria and Switzerland in 2011-2015 : Scientific publications by university hospitals in D­A-CH]. / Anästhesiologie-Publikationen aus Deutschland, Österreich und der Schweiz 2011­2015 : Wissenschaftliche Publikationen der Universitätskliniken in D­A-CH.

BACKGROUND: This study presents a count of publications and citations for all articles published by university Departments of Anaesthesiology in Germany, Austria and Switzerland between 2011 and 2015. The results were compared with former analyses of these countries from 2001-2010 as well as similar international studies. METHODS: We performed a PubMed search based on PERL-scripts for all publications originating from university Departments of Anaesthesiology in Germany, Austria and Switzerland between 2011 and 2015. According to their author's affiliation, articles were assigned to their affiliated university department. Publications were considered an original article if the category of publication was classified as original research in PubMed. Predatory journals were omitted by using PubMed-listed journals only. Data of citations was retrieved from Thomson Reuter's ISI Web of Knowledge. The following indicators were reported: the number of publications and original articles (counting each author and first authors only) and the share of original articles out of all publications. With regard to citations, we reported the overall number, the percentage of publications, which were cited at least once and the median of citations per publication and per original article as well as the calculated h-index. RESULTS: The 47 university Departments of Anaesthesiology published 4.697 articles between 2011 and 2015, which make up 89% of all anaesthesiology research originating from Germany, Austria and Switzerland (overall 5.284 publications). Of these, 1.037 (22%) were classified as original articles. Considering only articles with first authors, equalizing a change of PubMed's affiliation field policy in 2012 to compare the numbers with previous periods, 3.709 publications and 821 original articles were published. 90% of all publications and 96% of original articles, respectively, were cited at least once. Publications were cited six times, while original articles were cited nine times. The university department of Anaesthesiology in Zurich published most (n = 245), while most original articles were published in Vienna (n = 77). The highest share of original articles was achieved by Vienna (37%). Publications from Berlin - Benjamin Franklin and Jena (11 citations per publication) and original articles from Essen (23,5 citations per original article) achieved the highest citation rates. DISCUSSION: In contrast to the worldwide increasing trend, the number of publications of the university Departments of Anaesthesiology in Germany, Austria and Switzerland stagnated. The share of original articles out of all publications continues to decline in comparison to 2001-2010 (-6%). Despite this, original articles were cited more frequently and thus had a higher value for the scientific community. The reasons of the decrease in the number of original articles remain unclear and require further investigation to reverse this negative trend. CONCLUSION: Strategies to foster academic work in anaesthesiology in Germany, Austria and Switzerland are required.

A comparison of the suction laryngoscope and the Macintosh laryngoscope in emergency medical technicians: a manikin model of severe airway haemorrhage.

The use of a suction laryngoscope that enables simultaneous suction and laryngoscopy was evaluated. 34 emergency medical technicians intubated the trachea of a manikin with simulated upper airway haemorrhage using the suction laryngoscope and the Macintosh laryngoscope, in random order. When using the suction laryngoscope, the number of oesophageal intubations was lower (3/34 vs 11/34; p=0.021) and the time taken to intubation was shorter (mean (SD) 50 (15) vs 58 (27) s; p=0.041). In cases of airway haemorrhage, the use of the suction laryngoscope might be beneficial.

[Death due to (no) airway. Adverse events by out-of-hospital airway management?]. / Tod durch (k)einen Atemweg. Trauma durch die präklinische Atemwegssicherung?

Securing the airway is a rarely performed procedure in the out-of-hospital setting. In recent years evidence has been accumulated indicating that out-of-hospital airway management is more challenging as compared to elective situations even for experienced health care providers. Furthermore, several authors have questioned the benefit of out-of-hospital tracheal intubation. This review argues the problems regarding out-of-hospital airway management studies and discusses potential solutions which may improve out-of-hospital health care.

[False positive death certification. Does the Lazarus phenomenon partly explain false positive death certification by rescue services in Germany, Austria and Switzerland?]. / Falsch-positive Todesfeststellungen. Erklärt das Lazarus-Phänomen teilweise falsch-positive Todesfeststellungen im Rettungsdienst in Deutschland, Osterreich und der Schweiz?

Apart from misdiagnosis, the Lazarus phenomenon, a spontaneous return of circulation after cardiac arrest, is a potential cause for false positive death certification. Because of medicolegal consequences and thus a negative publication bias, the incidence of false positive death certification is unknown. As a false positive death certification results in criminal prosecution and thus media interest, numerous media archives in Germany, Austria and Switzerland were searched for such reports. A total of nine cases of false positive death certification in these three countries were identified since the early 1990s of which eight occurred in an emergency medical service system setting. Apart from a lack of diligence of emergency physicians, a Lazarus phenomenon could be the reason for such incidents. As definite signs of death will not have developed only a few minutes after stopping CPR it might be difficult for an emergency physician to definitely certify a patient's death in an out-of-hospital setting with 100% safety. Thus, prehospital death certification poses a risk of error and subsequent legal prosecution of the emergency physician, as a Lazarus phenomenon may still occur in this phase. Delegation of death certification from emergency physicians to qualified physicians in a follow-up examination might increase both legal safety for emergency physicians in the field and patient safety.

Optimising the unprotected airway with a prototype Jaw-Thrust-Device--a prospective randomised cross-over study.

Despite being a standard procedure during induction of anaesthesia, facemask ventilation can be a major challenge especially for inexperienced anaesthetists. We manufactured a Jaw-Thrust-Device designed to keep the patient's jaws in an optimised position, and thus to maintain the airway in a permanently patent state. Using a cross over design, we compared the influence of using the Esmarch manoeuvre (bimanual jaw-thrust), a nasopharyngeal airway, an oropharyngeal airway, or the Jaw-Thrust-Device on airway physiology in 50 healthy adults with body mass index < 35 kg.m(-2), undergoing standard facemask ventilation for routine induction of anaesthesia. The main study endpoints were expiratory tidal volumes, airway resistances, and gas flow rates. The Jaw-Thrust-Device was more effective in increasing expiratory tidal volumes and peak inspiratory flow than a standard Esmarch manoeuvre, and was more effective than both nasopharyngeal and oropharyngeal airways in decreasing airway resistance.

Effect of decreased inspiratory times on tidal volume. Bench model simulating cardiopulmonary resuscitation.

BACKGROUND: During cardiopulmonary resuscitation (CPR) with a chest compression rate of 60-100/min the time for secure undisturbed ventilation in the chest decompression phase is only 0.3-0.5 s and it is unclear which tidal volumes could be delivered in such a short time. OBJECTIVES: Attempts were made to assess the tidal volumes that can be insufflated in such a short time window. METHODS: In a bench model tidal volumes were compared in simulated non-intubated and intubated patients employing an adult self-inflating bag-valve with inspiratory times of 0.25, 0.3, and 0.5 s. Respiratory system compliance values were 60 mL/cmH(2)O being representative for respiratory system conditions shortly after onset of cardiac arrest and 20 mL/cmH(2)O being representative for conditions after prolonged cardiac arrest. RESULTS: With a respiratory system compliance of 60 mL/cmH(2)O, tidal volumes (mean+/-SD) in non-intubated versus intubated patients were 144+/-13 mL versus 196+/-23 mL in 0.25 s (p<0.01), 178+/-10 versus 270+/-14 mL in 0.3 s (p<0.01), and 310+/-12 mL versus 466+/-20 mL in 0.5 s (p<0.01). With a respiratory system compliance of 20 mL/cmH(2)O, tidal volumes in non-intubated patient versus intubated patients were 128+/-10 mL versus 186+/-20 mL in 0.25 s (p<0.01), 158+/-17 versus 250+/-14 mL in 0.3 s (p<0.01) and 230+/-21 mL versus 395+/-20 mL in 0.5 s (p<0.01). CONCLUSIONS: Ventilation windows of 0.25, 0.3, and 0.5 s were too short to provide adequate tidal volumes in a simulated non-intubated cardiac arrest patient. In a simulated intubated cardiac arrest patient, ventilation windows of at least 0.5 s were necessary to provide adequate tidal volumes.

[Fatalities due to nitrous oxide. Complications from mistakes in nitrous oxide supply]. / Lachgasbedingte Todesfälle. Komplikationen durch Verwechslungen in der Lachgaszufuhr.

Despite inspiratory oxygen fraction measurement being regulated by law in the European norm EN 740, fatal errors in nitrous oxide delivery still occur more frequently than expected, especially after construction or repair of gas connection tubes. Therefore, if nitrous oxide is to be used further in a hospital, all technical measures and system procedures should be employed to avoid future catastrophes. Among these are measurement of the inspiratory oxygen fraction (F(I)O(2)) and an automatic limitation of nitrous oxide. Also all anaesthetists involved should be informed about repair or construction of central gas supply tubes. Additionally, more awareness of this problem in daily routine is necessary. Furthermore, a system of detecting and analysing errors in anaesthesia has to be improved in each hospital as well as in the anaesthesia community as a whole. Measures for a better "error culture" could include data exchange between different critical incident reporting systems, analysis of closed claims, and integration of medical experts in examination of recent catastrophes.

Fatal errors in nitrous oxide delivery.

Nitrous oxide continues to be used frequently and the possibility of inadvertent fatal hypoxaemia resulting from technical errors with its administration still exists. A Medline analysis revealed only a few case reports over the last 30 years, and a closed claim analysis only reported 'claims involving oxygen supply lines' predating 1990. The aim of this study was to assess the frequency of nitrous oxide-related catastrophes during general anaesthesia in Germany, Austria, and Switzerland. As nitrous oxide-related anaesthesia casualties are rare but generally prosecuted, they almost invariably attract significant media attention. We scanned mass media archives from April 2004 until October 2006 for nitrous oxide-related disasters during general anaesthesia. This approach detected six incidents which were almost certainly nitrous oxide ventilation-related deaths. Searching non-scientific data bases demonstrates that severe incidents involving oxygen supply lines occurred after 1990, and may be much more frequent than previously thought.

[Therapeutic hypothermia in 2015 : Influence of the TTM study on the intensive care procedure after cardiac arrest]. / Therapeutische Hypothermie im Jahr 2015 : Einfluss der TTM-Studie auf das intensivmedizinische Prozedere nach Kreislaufstillstand.

BACKGROUND: In the 1960s, Peter Safar et al. postulated the benefit of postcardiac arrest hypothermia after successful cardiopulmonary resuscitation (CPR). However, therapeutic hypothermia postCPR did not become a standard procedure until the first few years of the new millennium. Various noninvasive and invasive cooling methods are available. Generally, more invasive cooling methods are more effective-but also tend to involve more complications. Furthermore, invasive measures need more time and thus may be instituted late in the postCPR process, delaying the cooling efforts in the initial phase. There is ongoing controversy about when best to commence cooling. CURRENT SITUATION: Recent studies of initial out-of-hospital cooling did not show any benefit for the patients compared to starting cooling in the hospital. The exact target temperature is the subject of multiple ongoing discussions. A recent study showed no disadvantage of cooling to 36 ℃ compared to 33 ℃, which is in the widely accepted standard target temperature range of 32-34 ℃. Nevertheless, cooling to 32-34 ℃ according to the 2010 guidelines is still the accepted standard procedure unless and until new studies generate more evidence. The European Resuscitation Council has given advance notice of a statement on the optimal target temperature in the near future. Finally, large registry studies have demonstrated the benefit of combining postCPR hypothermia with early percutaneous cardiac interventions (PCI) in acute coronary syndromes, which are often a cause of cardiac arrest. OUTLOOK: Transport of patients after CPR to specialized postcardiac arrest centres with the possibility of acute PCI and cooling, comparable to the transfer of multiple trauma patients to trauma centres, may be beneficial.

[Ventilation of an unprotected airway: evaluation of a new peak-inspiratory-flow and airway-pressure-limiting bag-valve-mask]. / Beatmung eines ungeschützten Atemwegs: Evaluation eines neuen spitzenfluss- und druckbegrenzenden Beatmungsbeutels.

BACKGROUND: Currently 30 chest compressions and 2 ventilations with an inspiratory time of 1 s are recommended during cardiopulmonary resuscitation with an unprotected airway, thus spending about 15% instead of 40% of resuscitation time on ventilation. Time could be gained for chest compressions when reducing inspiratory time from 2 s to 1 s, however, stomach inflation may increase as well. METHODS: In an established bench model we evaluated the effect of reducing inspiratory time from 2 s to 1 s at different lower oesophageal sphincter pressure (LOSP) levels using a novel peak inspiratory-flow and peak airway-pressure-limiting bag-valve-mask device (Smart-Bag). RESULTS: A reduction of inspiratory time from 2 s to 1 s resulted in significantly lower peak airway pressure with LOSP of 0.49 kPa (5 cm H2O), 0.98 kPa (10 cm H2O) and 1.47 kPa (15 cm H2O) and an increase with 1.96 kPa (20 cm H2O). Lung tidal volume was reduced with 1 s compared to 2 s. When reducing inspiratory time from 2 s to 1 s, stomach inflation occurred only at a LOSP of 0.49 kPa (5 cm H2O). CONCLUSIONS: In this model of a simulated unprotected airway, a reduction of inspiratory time from 2 s to 1 s using the Smart-Bag resulted in comparable inspiratory peak airway pressure and lower, but clinically comparable, lung tidal volume. Stomach inflation occurred only at a LOSP of 0.49 kPa (5 cm H2O), and was higher with an inspiratory time of 2 s vs 1 s.