Neurally adjusted ventilatory assist vs. pressure support ventilation in critically ill patients: an observational study.

BACKGROUND: During neurally adjusted ventilatory assist (NAVA), the inspiratory support is controlled by the patients' respiratory drive influenced by an operator-controlled gain factor (NAVA level). The purpose of our observational study was to transfer patients from conventional pressure support ventilation (PSV) to NAVA safely. We compared two approaches to set the NAVA level and evaluated the effect of NAVA. METHODS: We studied mechanically ventilated patients capable of spontaneous breathing. For the change of the ventilator mode, we used a NAVA level calculated to generate a peak inspiratory pressure equal to PSV. We compared this NAVA level with a NAVA level determined by a NAVA level titration. Ventilatory and haemodynamic data were recorded during an observational period of 6 h. RESULTS: All 20 patients included in the study could be transferred from PSV to NAVA and completed the observation interval. Setting the NAVA level according to prior PSV settings proved to be a feasible approach, but in 75% of our patients, we modified the NAVA level according to the titration results. Gas exchange and ventilatory mechanics during the observation interval remained stable. CONCLUSIONS: The ventilator mode NAVA seems to be well tolerated in a heterogeneous group of critically ill patients. Pre-setting of the NAVA level during PSV can result in an overestimation of the required ventilator support. An additional titration of the NAVA level ads valuable information although difficult to interpret in some cases.

[Neurally adjusted ventilatory assist (NAVA). A new mode of assisted mechanical ventilation]. / "Neurally adjusted ventilatory assist" (NAVA). Ein neuartiges assistiertes Beatmungsverfahren.

The aim of mechanical ventilation is to assure gas exchange while efficiently unloading the respiratory muscles and mechanical ventilation is an integral part of the care of patients with acute respiratory failure. Modern lung protective strategies of mechanical ventilation include low-tidal-volume ventilation and the continuation of spontaneous breathing which has been shown to be beneficial in reducing atelectasis and improving oxygenation. Poor patient-ventilator interaction is a major issue during conventional assisted ventilation. Neurally adjusted ventilator assist (NAVA) is a new mode of mechanical ventilation that uses the electrical activity of the diaphragm (EAdi) to control the ventilator. First experimental studies showed an improved patient-ventilator synchrony and an efficient unloading of the respiratory muscles. Future clinical studies will have to show that NAVA is of clinical advantage when compared to conventional modes of assisted mechanical ventilation. This review characterizes NAVA according to current publications on this topic.

Intubating laryngeal mask airway for difficult out-of-hospital airway management: a prospective evaluation.

BACKGROUND: Out-of-hospital airway management is a critical skill, demanding expert knowledge and experience. The intubating laryngeal mask airway (ILMA) is a ventilatory and intubating device which may be of value in this arena. We evaluated the ILMA for out-of-hospital management of the difficult airway. METHODS: Twenty-one anaesthesia-trained emergency physicians (EPs) completed a training programme and used the ILMA in patients with difficult-to-manage airways. Indications for use of the ILMA included patients with difficult laryngoscopy, multiple intubation attempts, limited access to the patient's head, presence of pharyngo-laryngeal trauma, and gastric fluids or bleeding obscuring the view of the vocal cords. RESULTS: During the study period, 146 of 2513 patients underwent tracheal intubation or alternate rescue airway insertion. In 135 patients, laryngoscopy was performed and Cormack-Lehane view was recorded as grade I in 72 (53.3%), II in 45 (33.3%), III in 10 (7.4%), and IV in 8 (5.9%). EPs encountered 11 patients (7.5%) with difficult-to-manage airways. ILMA insertion and ventilation was possible in 10 patients in the first and one patient in the second attempt. ILMA-guided tracheal intubation was successful in all patients, in 10 after the first and in 1 after two attempts. CONCLUSIONS: In this study, ventilation and intubation with ILMA was successful in all patients with difficult-to-manage airways. Our data support the use of the ILMA as rescue device for out-of-hospital airway management by staff who have appropriate airway skills and have received appropriate training.

[Teaching and simulation. Methods, demands, evaluation and visions]. / Lehre und Simulation. Methoden, Anforderungen, Evaluation und Visionen.

Since 1st October 2003 the new German "Approbationsordnung für Arzte" (Medical Licensing Regulations) requires an increasing amount of small group teaching sessions and encourages a multidisciplinary and more practical approach to the related topics. In 2004 the German Society of Anaesthesiology and Intensive Care Medicine has provided almost all anaesthesia faculties of German Universities with equipment for full-scale simulation. This article describes methods for a simulation-based medical education training program. Basic requirements for a successful training program using full scale simulators are the provision of an adequate logistical and material infrastructure, teacher attendance of train-the-trainer courses, implementation in the medical curriculum and an instructor-student ratio of 1:3, equivalent to that for bedside teaching. If these requirements were fulfilled, medical students scored the simulation scenarios "induction of anaesthesia", "acute pulmonary embolism", "acute management of a multiple trauma patient" and "postoperative hypotension" as 1.5, 1.6, 1.5 and 1.5, respectively, on a scale of 1-6. These scores were better than those given for other segments of the curriculum.

[New pathways in undergraduate medical education - first experiences with the cross section speciality emergency and intensive care medicine]. / Neue Wege der studentischen Lehre - Erste Erfahrungen im Querschnittsbereich Notfall- und Intensivmedizin.

OBJECTIVE: On October 1 (st) 2003 Emergency Medicine was recognised for the first time as an independent cross section speciality in the new German "Approbationsordnung fuer Aerzte" (Medical Licensing Regulations). These amendments were made not only to increase the amount of small group teaching sessions but also to encourage a multidisciplinary and rather practical approach to the related topics. This article portrays the realisation of these objectives in form of a multidisciplinary module, as it has been established at University of Göttingen Medical School since the summer semester of 2004. We present the new curriculum, calculate the associated personnel resources and demonstrate the results of the structured evaluation given by the participating students. METHODS: We linked the fields of emergency and intensive care medicine by splitting them up into submodules which the students had to run through according to a set rota. 162 students were allocated to 27 small groups. Every student received a total of 38.5 hours of teaching, with the workshops coming to 46.8 %. The workshops comprised of nine sessions, three in Emergency Medicine, four in Intensive Care Medicine and two at human patient simulators. In addition we scheduled a seminar and an accompanying lecture. The final examination was performed as an Objective Structured Clinical Evaluation (OSCE). RESULTS: The realisation of the new module required a total of 1290 working hours for medical staff and 130 for our student aids. Compared to all other modules of Goettingen University Medical School the module here presented obtained the highest overall evaluation score by the medical students. Lessons with a high amount of practical involvement (i. e. Emergency Medicine and simulator-based workshops) were significantly better evaluated than rather formal teaching techniques, such as the lectures and the seminar. According to the students' self-assessment the simulator-based workshops were seen particularly valuable for the facilitation of knowledge transfer into clinical practice. CONCLUSION: The determined realisation of the new German Medical Licensing Regulations requires considerable time resources. However, its evaluation by the medical students is strikingly positive.

[Simulation and airway management]. / Simulation und Atemwegsmanagement.

Despite the development of new devices and strategies to manage and secure the difficult airway, morbidity and mortality in anaesthesia due to airway problems such as difficult intubation or unrecognised failed intubation remain high. The problem seems to lie in the transfer of skills and strategies to daily clinical practice. Common methods for airway management training include theoretical instructions and hands-on sessions with manikins, animal models and cadavers. Simulation provides the opportunity to train skills and resolve specific situations embedded in a realistic scenario, facilitate the transfer of cognitive, psychomotor and affective abilities into daily clinical practice and help to improve behaviour in critical situations. This article outlines new training concepts in airway management with the help of simulation and simulators. We describe technical prerequisites and provide information on the implementation of difficult airway scenarios.

[Lactic acidosis and acute abdomen from biguanide intoxication]. / Laktatacidose und akutes Abdomen bei Biguanidintoxikation.

Metformin, an anti-hyperglycaemic drug, reduces mortality in obese patients with a non-insulin-dependent diabetes mellitus type II (United Kingdom Prospective Diabetes Study) and is therefore recommended as the first line therapy. A metformin-associated lactic acidosis due to accumulation or intoxication is a rare but severe complication with a mortality rate of up to 50%. The main clinical symptoms are unspecific and the patient may present with acute abdominal pain and reduced consciousness. This can easily be misinterpreted and may lead to a wrong diagnosis. Only a thorough clinical examination and exact analysis of laboratory values in combination with the medical history and chronic medication will allow a correct diagnosis. We report a case of a 79-year-old female patient whose clinical symptoms were initially interpreted as an acute intestinal ischemia. A progressively deteriorating haemodynamic state led to an exploratory laparotomy. Postoperatively, the correct diagnosis of a metformin-associated lactic acidosis due to acute renal failure was made. In the course of the ICU stay the condition improved after bicarbonate haemodialysis and the patient was discharged 11 days after admission.

[Blood gas analysis in interhospital transfer--a useful extension of respiratory monitoring?]. / Blutgasanalyse im Interhospitaltransfer--eine sinnvolle Ergänzung des respiratorischen Monitorings?

OBJECTIVE: Investigation of blood gas analysis during hospital-to-hospital transport of ventilated ICU-patients to detect critical events, changes of gas exchange and reliability of non-invasive monitoring. METHODS: 47 ventilated patients (age 9-76 years, mean 50 years, diagnosis: ARDS = 16, intracranial bleeding = 14, severe trauma = 4, acute hemodynamic failure = 3, others = 10), transported by a special physician staffed intensive care ambulance using invasive hemodynamic monitoring. Blood gas analysis was performed before and during transport every 30 minutes and respirator mode, vital signs and events were documented. RESULTS: In 19 (40.4%) patients there were critical events during transport (paO2 < 70 mmHg, paCO2 < 25 mmHg, paCO2 > 55 mmHg, pH < 7.30, pH > 7.55). In 4 patients with PaO2 < 70 mmHg there was SpO2 > or = 97% (by pulsoximetry), correlation between SaO2 (invasive) and SpO2 (by pulsoximetry) was r = 0.81 (P < 0.001) with a maximum difference of 8 percent. In several patients critical changes of condition could be recognized in an early stage by blood gas analysis. CONCLUSIONS: Blood gas analysis during hospital-to-hospital transport of ICU-patients can be performed easily and allows to optimize artificial ventilation and to recognize earlier and safer severe problems of gas exchange.