Validity and fidelity of the upper airway in two high-fidelity patient simulators.

BACKGROUND: Human patient simulators are frequently used for airway management training and research. However, little is known about their fidelity and validity. The use of these simulators as a benchmark model remains highly questionable. The objective of this study was to evaluate the validity and fidelity of two patient simulators (compared to actual patients) for anaesthesia residents performing three airway management techniques. METHODS: Endotracheal intubation, laryngeal mask airway insertion and mask ventilation were performed by anaesthesia residents on 80 patients undergoing elective surgery. The anaesthesia residents also used these three techniques to secure the airways of two human patient simulators in a randomised crossover study. The durations, difficulties, realism and success rates of the procedures were assessed. RESULTS: Although the performance of endotracheal intubation was comparable in patients and both manikins, no chest rise was visible in 35% (HAL) and 32.5% (SimMan) of the manikins after inserting a laryngeal mask airway. This result was not observed in patients (P<0.001). Furthermore, effective mask ventilation was not possible in 60% of the cases using HAL, compared with 0% of cases using SimMan and 2.5% of patients (P<0.001). CONCLUSION: Patient simulators are not a valid alternative to human patients for conducting scientific evaluations of supraglottic airway management techniques. HAL and SimMan do have adequate validity for endotracheal intubation, but the fidelity and validity are low when a laryngeal mask is used or if mask ventilation is performed. Therefore, previous simulation-based airway device evaluation studies must be interpreted with great caution.

Can a flowchart improve the quality of bystander cardiopulmonary resuscitation?

BACKGROUND: Since the introduction of basic life support in the 1950s, on-going efforts have been made to improve the quality of bystander cardiopulmonary resuscitation (CPR). Even though bystander-CPR can increase the chance of survival almost fourfold, the rates of bystander initiated CPR have remained low and rarely exceed 20%. Lack of confidence and fear of committing mistakes are reasons why helpers refrain from initiating CPR. The authors tested the hypothesis that quality and confidence of bystander-CPR can be increased by supplying lay helpers with a basic life support flowchart when commencing CPR, in a simulated resuscitation model. MATERIALS AND METHODS: After giving written informed consent, 83 medically untrained laypersons were randomised to perform basic life support for 300s with or without a supportive flowchart. The primary outcome parameter was hands-off time (HOT). Furthermore, the participants' confidence in their actions on a 10-point Likert-like scale and time-to-chest compressions were assessed. RESULTS: Overall HOT was 147±30 s (flowchart) vs. 169±55 s (non-flowchart), p=0.024. Time to chest compressions was significantly longer in the flowchart group (60±24 s vs. 23±18 s, p<0.0001). Participants in the flowchart group were significantly more confident when performing BLS than the non-flowchart counterparts (7±2 vs. 5±2, p=0.0009). CONCLUSIONS: A chart provided at the beginning of resuscitation attempts improves quality of CPR significantly by decreasing HOT and increasing the participants' confidence when performing CPR. As reducing HOT is associated with improved outcome and positively impacting the helpers' confidence is one of the main obstacles to initiate CPR for lay helpers, charts could be utilised as simple measure to improve outcome in cardiopulmonary arrest.

Impact of the European Paediatric Life Support course on knowledge of resuscitation guidelines among Austrian emergency care providers.

BACKGROUND: Even though anaesthetists do not resuscitate children on a daily basis, they need to perform paediatric life support regularly due to their different duties. As the knowledge of international guidelines varies widely, highly standardized European Paediatric Life Support (EPLS) courses have been introduced to improve standards of care. This national survey among Austrian anaesthetists and EPLS course participants evaluated the impact of this course at the end of the guideline period 2005-2010. METHODS: After approval by the institutional review board an online survey about paediatric resuscitation guidelines was sent to EPLS course participants of the guideline period 2005 (EPLS group) and members of the Austrian Society of Anaesthesia, Resuscitation and Intensive Care (ÖGARI) two weeks before publication of the resuscitations guidelines 2010. Respondents without an EPLS course were assigned to the non-EPLS group. RESULTS: Of 333 respondents 247 finished the survey. One hundred eighty five persons were assigned to EPLS group and 62 to the non-EPLS group. Members of the EPLS group performed significantly better than the non-EPLS group (76 ± 19% correct answers EPLS group vs. 63 ± 18% correct answers non-EPLS group, p<0.0001). Furthermore, the EPLS group performed better than anesthetists with regular resuscitation training and or resuscitation experience but without an EPLS course. CONCLUSION: The attendance of an EPLS course within the guideline period 2005 significantly increased the theoretical knowledge of paediatric resuscitation guidelines.

[Near infrared stimulation of the equilibrium organ--first clinical experiences]. / Nahinfrarotreizung des Gleichgewichtsorgans--erste klinische Erfahrungen.

BACKGROUND: A new method for the stimulation of the organ of equilibrium by means of a broad-scale and monochromatic near infrared emission was developed. This method should be examined within the framework of a pilot study, evaluated and its clinical possible applications examined. PATIENTS AND METHODS: Healthy probands (n = 15), patients with a radical cave of the ear (n = 5), patients with a defect of the tympanic membrane (n = 5) and spontaneous nystagmus (n = 5) were examined. In healthy probands an irritation with broad-scale as well as monochromatic near infrared (NIR) was performed and compared with a water irrigation (44 degrees, 50 ml in 30 seconds). The subjective, local feelings during the application and the appearance of giddiness according to irritation were recorded and the nystagmus was registered by means of videonystagmography. In patients with radical cave of the ear and tympanic membrane defects, a broad-scale NIR-irritation before a comparative irritation with warm air (44 degrees) was performed exclusively. RESULTS: In all healthy probands, a nystagmus reaction could be seen with broad-scale and monochromatic NIR. Compared to the hot water irritation slow phase velocity (SPV) was decreased however registrable by means of Frenzel glasses and electronystagmography during the culmination stage. In patients with radical cave (n = 4) and tympanic membrane defects (n = 3) showing paradoxical nystagmus reaction during hot air irritation, a nystagmus to the site of stimulation resulted by means of light calorisation. In patients with a spontaneous nystagmus an attenuation (n = 1) or inversion (n = 2) could be achieved by NIR-radiation. CONCLUSIONS: The method of the NIR-radiation is suitable in clinical practice for the caloric test proofing warm reaction. Vaporization cold does not occur. The application of heat charm is better proportionable and steerable than during air irritation. The procedure is sterile, noiseless and non-contact. Difficulties in interpretation of results of vestibular tests because of evaporation coldness do not occur.

Collagen microparticles: preparation and properties.

Collagen microparticles (CMPs) of diameters ranging from about 3 to 40 microns were prepared by the method of emulsifying and cross-linking native collagen. The particle size was mainly controlled by the molecular weight of the collagen used: an increase in denaturation of the collagen resulted in smaller particle sizes. Consequently, controlled denaturation is the best method to control the size of CMPs. Total denaturation results in the degradation product gelatin and subsequently yields very small nanoparticles with a minimum diameter of about 0.1 micron. Collagen microparticles can be used as carriers for lipophilic drugs e.g. retinol, tretinoin, or tetracaine and lidocaine in free base form. Another feature of the biodegradable CMPs is their thermal stability, thus their sterilization can be readily achieved.

Effect of collagen microparticles on the stability of retinol and its absorption into hairless mouse skin in vitro.

Collagen microparticles (CMPs) were manufactured with the objective to enhance the dermal delivery of all-trans retinol. The influence of CMPs on the stability of retinol was investigated after a long-term storage of two hydrogel preparations (hydroxyethylcellulose). The retinol in the first preparation was adsorbed onto the surface of CMPs, whereas the retinol in the second preparation was freshly precipitated. Retinol was not protected from oxidization by adsorption to CMPs. However, the sorption on the surface of CMPs prevented the retinol from crystallization. On the other hand, significant crystallization occurred with the freshly precipitated retinol. For the study of the in vitro penetration of retinol into hairless mouse skin three preparations for topical application were used. Beside the two hydrogel preparations mentioned above, an O/W-creme was tested. The study of the in vitro penetration was performed by using Franz diffusion cells and tritium labelled retinol. Both hydrogel preparations yielded significantly higher quantities of penetrated retinol than the O/W-creme. The amounts of radioactive retinol in the stratum corneum and in the epidermis and dermis were in all cases more than ten times higher for the hydrogel preparations. The other remarkable result was that the presence of CMPs led to a faster and higher transport of retinol into the skin than the freshly precipitated drug. With the CMP preparation a statistically significant increase of penetrated retinol was found during the first 4 h after application in the stratum corneum. In the residual epidermis and dermis a clear tendency towards enhanced quantities of penetrated retinol also were observed with the CMPs compared to the freshly precipitated drug in the hydrogel.