Influence of Electromagnetic Fields on Function of Automated External Defibrillators

Objectives: In this study, the authors tested whether electromagnetic interference (EMI) is able to impair correct electrocardiogram analysis and produce false‐positive shock advice from automated external defibrillators (AEDs) when the true rhythm is sinus. Methods: Nineteen healthy subjects were used to test five AEDs available on the Austrian market in a prospective, open, and sequence‐randomized study. The primary outcome variable was the absolute number of shocks advised in the presence of EMI. The secondary outcome was the number of impaired analyses caused by incorrectly detected patient movements or electrode failure. Results: Of 760 tests run, 18 (2.37%) cases of false‐positive results occurred, and two of five AEDs recommended shocks in the presence of sinus rhythm. Of 760 tests run, no electrode failures occurred. There were 27 occurrences (3.55%) of motion detected by an AED in the presence of strong electromagnetic fields. Conclusions: AED models differ in their response to EMI; it may be useful to consider specific safety requirements for areas with such fields present. Working personnel and emergency medical services staff should be informed about potential risks and the possible need for patient evacuation before AEDs are attached and shock recommendations are followed.     

Taxonomic and diagnostic markers for identification of Coccidioides immitis and Coccidioides posadasii.

The ribosomal Internal Transcribed Spacer (ITS) regions of the two recognized species of Coccidioides were studied using a reference set of strains that had been previously identified with species defining microsatellite polymorphisms. Unambiguous identification of the two species proved to be possible by amplifying and sequencing the ITS region. PCR-reactions are sensitive to amplification conditions requiring their careful optimization. Stable amplification and sequencing was achieved with primers ITS3 and 4, enabling species diagnosis. Alternatively, Restriction Fragment Length Polymorphism (RFLP) of the entire ITS region using an annealing temperature of 52 degrees C with the restriction enzymes BsrI and XcmI can also distinguish the species. Three strains typifying the species, Glenospora meteuropaea, G. metamericana and Geotrichum louisianoideum, were analyzed and found to be conspecific with C. posadasii. Although these species have nomenclatural priority over C. posadasii, the latter will be proposed for conservation as it has been included in the US select agent list. In addition, Coccidioides immitis is neotypified in this report. Results of antifungal susceptibility testing did not reveal differences between the two species.     

Noninvasive monitoring of rotary blood pumps: necessity, possibilities, and limitations

Although rotary blood pumps do not contain an inherent mechanism for adaptation to physiological flow necessities, hitherto only a few efforts have been made to obtain robust monitoring and control methods. This paper discusses the necessity of noninvasive monitoring of such pumps and the crucial points of sensor selection and development. A strategy of monitoring atrial pressure out of the data obtained by the collapse of the atrial wall around the inflow cannula and initial results on animal tests and computer simulation of this method are discussed. This approach might lead to reliable and demand-responsive controllers, if some basic criteria are fulfilled.     

Emergency preservation and resuscitation improve survival after 15 minutes of normovolemic cardiac arrest in pigs

OBJECTIVE: Outcome after prolonged normovolemic cardiac arrest is poor, and new resuscitation strategies have to be found. We hypothesized that the induction of deep hypothermia for emergency preservation and resuscitation (EPR) during prolonged cardiac arrest, before the start of reperfusion, will mitigate the deleterious cascades leading to neuronal death and will thus improve outcome. DESIGN: Prospective experimental study. SETTING: University research laboratory. SUBJECTS: Thirteen pigs, Large White breed (27-37 kg). INTERVENTIONS: After 15 mins of ventricular fibrillation, pigs were subjected to 1) EPR (n = 6), 20 mins of hypothermic stasis induced with a cold saline aortic flush; or 2) 20 mins of conventional resuscitation (n = 7). Then cardiopulmonary bypass was initiated in both groups, followed by defibrillation. Controlled ventilation and mild hypothermia were continued for 20 hrs; survival was for 9 days. For neurologic evaluation, neurologic deficit score (100% = brain dead, 0-10% = normal), overall performance category (1 = normal, 5 = dead or brain dead), and brain histologic damage score were used. MEASUREMENTS AND MAIN RESULTS: In the EPR group, brain temperature decreased from 38.5 degrees C +/- 0.2 degrees C to 16.7 degrees C +/- 2.5 degrees C within 235 +/- 27 secs. Five animals achieved restoration of spontaneous circulation and survived to 9 days: two pigs with overall performance category 2 and three pigs with overall performance category 3. Their neurologic deficit score was 45% (interquartile range 35, 50) and histologic damage score was 142 (interquartile range 109, 159). In the control group, four pigs achieved restoration of spontaneous circulation: one survived to 9 days with overall performance category 3, neurologic deficit score 45%, and histologic damage score 226 (restoration of spontaneous circulation, p = .6; survival, p = .03; overall performance category, p = .02). CONCLUSIONS: EPR is feasible in an experimental pig model and improves survival after prolonged cardiac arrest in pigs. Further experimental studies are needed before this concept can be brought into clinical practice.     

Laryngeal pacemaker: activity of the posterior cricoarytenoid muscle (PCM) and the diaphragm during respiration in sheep

Electromyograms (EMG) of the PCM and the diaphragm were evaluated in 6 sedated female sheep. Corresponding pneumatograms were recorded simultaneously by means of thermocontrolled respiration flowmeter. Evidence was obtained on considerable intra- and inter-individual differences in the duration of respiratory cycles as well as PCM- and diaphragmatic activity. Most of the evaluated respiratory periods showed either a phase coincidence between the PCM and the diaphragm, or a leading edge of about 40-80 ms of the posticus muscle. Due to this minimal phase shift, the diaphragmatic myogram seems to be a valuable trigger for an external PCM stimulation unit in bilateral recurrent nerve palsy.     

Inhibition of neointimal formation after stent placement with adenovirus-mediated gene transfer of I kappa B alpha in the hypercholesterolemic rabbit model: initial results

PURPOSE: To evaluate the feasibility and efficacy of the local application of a replication-defective adenovirus construct for the expression of the antiinflammatory protein I kappa B alpha, inhibitor of nuclear factor kappa B (NF-kappa B), to reduce neointimal formation after stent placement. MATERIALS AND METHODS: Nitinol stents were implanted in the iliac arteries of hypercholesterolemic rabbits, followed by balloon dilation (30 seconds at 6 atm). Local adenovirus-mediated transfer of I kappa B alpha (3 mL of 10(9) plaque-forming units per milliliter at 6 atm) was performed and compared with three control groups: stent alone, stent plus local delivery of phosphate-buffered saline (PBS) (3 mL at 6 atm), and stent plus local delivery of control adenovirus coding for green fluorescent protein (GFP) (3 mL of 10(9) plaque-forming units per milliliter at 6 atm). A multichannel balloon was used for local drug delivery and balloon dilation. Animals were sacrificed 1 or 4 weeks after treatment. Effective transfection was demonstrated with immunofluorescence staining. Angiographic patency and luminal diameter were evaluated at quantitative angiography. Luminal and neointimal areas were measured on surface-stained ground sections with methylmethacrylate embedding and the cutting-grinding technique. RESULTS: All vessels with stents were patent at angiography. Neointimal area was negligible in all groups 1 week after stent placement (range, 0.42-0.52 mm(2); P =.44; analysis of variance). Neointimal formation was demonstrated in all groups 4 weeks after implantation but was significantly reduced with I kappa B alpha treatment compared with treatment with stent alone (by 22%, from 2.80 mm(2) +/- 0.20 to 2.28 mm(2) +/- 0.14, P =.05), stent plus PBS (by 43%, from 3.26 mm(2) +/- 0.25 to 2.28 mm(2) +/- 0.14, P =.005), and stent plus GFP (by 53%, from 2.32 mm(2) +/- 0.19 to 1.51 mm(2) +/- 0.08, P <.005). CONCLUSION: Local adenovirus-mediated I kappa B alpha gene transfer has the potential to reduce intimal hyperplasia after stent placement.     

Neovascularisation of the testes by experimental omentotesticulopexy

With the currently used surgical procedures, surgical correction of extreme forms of high undescended testes is associated with an atrophy rate of 10% to 30%. In this experimental study in two groups of Sprague-Dawley rats of pubescent age, we examined whether fixation (pexy) of an omental flap on the testis (omentotesticulopexy=OMTX) permits preservation of the viability of the parenchyma. A left-sided OMTX was performed in group 1 with the animals under general anaesthesia. An omental flap was prepared. The tunica albuginea of the testis planned for OMTX was pierced with a needle (26 × 23 G) within an area with a diameter of 1 cm; a puncture distance of 2 mm was used. The omental flap was then fixed using absorbable monofilament 6-0 interrupted sutures. Six weeks later the spermatic vessel was transected at this site. The right testis was left untouched throughout the procedure; it remained in situ. In group 2 only the spermatic vessel on the left side was severed. The right testis was not manipulated and remained in situ. After a total of 10 weeks both testes were removed from all rats and fixed in formalin. Standardised haematoxylin and eosin staining was performed and histological sections were obtained. The size of the testicles, Leydig-cell count, viability, and calcified areas within the tissue were determined for all testicles. Student's t-test was used for statistical evaluation. The study showed that OMTX leads to neovascularisation in the area of fixation and that viability can be preserved within this area. Accepted: 12 January 2000