Experience of a screening centre for influenza A/H1N1: the first 50 days.

BACKGROUND: The authors' emergency department (ED) served as Singapore's screening centre for influenza H1N1 cases. The aims of the study were to describe their screening experience and to compare clinical and laboratory features of H1N1 versus seasonal flu cases. METHODOLOGY: The authors conducted a prospective observational study on consecutive patients aged 16 years and above presenting to a busy, urban ED for H1N1 screening over 50 days. Clinical, laboratory, radiological and PCR data were collected from the hospital electronic databases. Primary outcomes were proportions of confirmed H1N1 cases and their distribution of clinical, laboratory and radiological features. Secondary outcomes were comparison of clinical and laboratory features of H1N1 versus seasonal flu cases. Data were analysed using descriptive statistics and univariate analysis was used to compare factors between the two groups. A p value <0.05 was considered statistically significant. RESULTS: 1205 patients were screened. 31 (2.6%) and 133 (11%) of them had H1N1 and seasonal flu infections, respectively. The two groups had similar symptoms. There were six clinical and two laboratory features with statistically significant differences between H1N1 and seasonal flu cases. Clinical factors were travel or contact history, median age, respiratory rate, diastolic blood pressure and length of hospital stay. Laboratory factors were median platelet and lymphocyte counts. CONCLUSIONS: The authors report their experience as the nation's H1N1 screening centre. They identified factors that were different between H1N1 and seasonal flu cases. Future research is needed to elucidate if and how this information can be used as a screening tool for H1N1.

Acoustic analysis of the closing sounds of bileaflet prosthetic valves in a sheep model.

Previous investigations of mechanical valve sounds have shown that (1) frequency spectra of sounds produced by abnormal valves differ from those of properly functioning valves and (2) leaflets of normally functioning bileaflet valves do not close synchronously. This investigation studied effects of mechanical valve size, environment, and hemodynamic state on closing sounds. A single 25 mm bileaflet mitral mechanical valve was implanted in six sheep and a single 27 mm valve in four sheep. With digital signal processing, asynchronous leaflet closure and frequency spectra were assessed after alterations in animal position, respiratory phase, heart rate, afterload, contractility, and preload. Both asynchronous leaflet closure and frequency spectra varied among animals, and, except for a decrease in asynchrony with increasing contractility, were largely independent of valve size and hemodynamics. Baseline asynchrony ranged from 0.5 to 4.2 msec. Frequency spectra were characterized by the first three resonant peaks. Lowest resonant peaks ranged from 2.5 to 3.4 kHz, middle from 4.7 to 6.8 kHz, and highest from 7.2 to 9.6 kHz. These results indicate that accurate assessment of mechanical valve function with acoustic analysis requires baseline studies in all patients by means of a system with a frequency response of more than 10 kHz.

Orthotopic total artificial heart bridge to transplantation: preliminary results.

A detailed summary of seven patients who received eight total artificial heart implants, including one Phoenix heart, two Jarvik 7-100 ml hearts, and five Jarvik 7-70 ml hearts, and nine heart transplants, reveals that bleeding, hemolysis, and thromboembolic and infectious problems are not the limiting factors. Size of the patient and the requirement for adequate space to permit adequate systemic and pulmonary venous filling seem to be the major limitations. Patients with a reasonable expectation of receiving a transplantation within 3 weeks are the best candidates for a bridge to transplantation. After this adhesions were found to cause severe technical problems at reoperation.

Systemic effects of multidose hypothermic potassium cardioplegia.

The purpose of this study was to investigate the changes in serum and urine potassium before, during, and after the administration of potassium cardioplegia using a solution containing 28 mEq/L of potassium chloride in 20 consecutive patients with acquired heart disease. The data obtained suggest that the concentration of potassium administered does not result in inordinately elevated serum potassium levels (peak, 4.6 +/- 0.18 mEq/L at 2 hours of multidose hypothermic potassium cardioplegia) during or after infusion. Additionally, the urinary excretion of potassium increased during infusion and eventually exceeded the amount of potassium infused. While hypothermic potassium cardioplegia appears to be a safe and efficient method of myocardial protection, continued surveillance of postoperative potassium levels remains necessary to detect obligatory urinary potassium excretion following cardiopulmonary bypass and operation.