A Technique for Rapid Bacterial-Density Enumeration through Membrane Filtration and Differential Pressure Measurements.

In this article, we present a microfluidic technique for the rapid enumeration of bacterial density with a syringe filter to trap bacteria and the quantification of the bacterial density through pressure difference measurement across the membrane. First, we established the baseline differential pressure and hydraulic resistance for a filtration membrane by fully wetting the filter with DI water. Subsequently, when bacteria were infused and trapped at the pores of the membrane, the differential pressure and hydraulic resistance also increased. We characterized the infusion time required for the bacterial sample to achieve a normalized hydraulic resistance of 1.5. An equivalent electric-circuit model and calibration data sets from parametric studies were used to determine the general form of a calibration curve for the prediction of the bacterial density of a bacterial sample. As a proof of concept, we demonstrated through blind tests with Escherichia coli that the device is capable of determining the bacterial density of a sample ranging from 7.3 × 106 to 2.2 × 108 CFU/mL with mean and median accuracies of 87.21% and 91.33%, respectively. The sample-to-result time is 19 min for a sample with lower detection threshold, while for higher-bacterial-density samples the measurement time is further shortened to merely 8 min.

Does pulmonary artery pulsatility index predict mortality in pulmonary arterial hypertension?

AIMS: Pulmonary artery pulsatility index (PAPi), defined as [(pulmonary artery systolic pressure - diastolic pulmonary artery pressure)/mean right atrial pressure], is a novel haemodynamic index that predicts right ventricular failure after myocardial infarction and left ventricular assist device implantation. We analysed if a low PAPi is associated with death in our 14 - â€‹year pulmonary arterial hypertension (PAH) registry. METHODS: Consecutive patients with newly diagnosed PAH and complete haemodynamic data were prospectively enrolled into our standing registry between January 2003 and December 2016. PAPi was calculated from baseline invasive right heart catheterization data. A prognostic cut-off value was determined with a decision tree. Baseline characteristics of 'high' and 'low' PAPi groups based on this cut-off were compared, as well as odds of death and time-to-death. RESULTS: One hundred and two patients were included. Mean age was 53 years, and 77% were women. Our multi-ethnic cohort was 64% Chinese, 23% Malay, and 10% Indian. The aetiologies were idiopathic (33%), connective tissue disease (31%), congenital heart disease (24%), and others (12%). The low PAPi group (<5.3) had a greater age (56 years vs. 49 years), lower pulmonary artery systolic pressure (71 mmHg vs. 85 mmHg), and higher mean right atrial pressure (14 mmHg vs. 6 mmHg). Mortality risk was higher in the low PAPi group (adjusted odds ratio: 2.98 and adjusted hazard ratio: 2.23). Mean right atrial pressure was the strongest predictor (hazard ratio 1.114, P = 0.009) when components of PAPi were analysed. CONCLUSIONS: Pulmonary artery pulsatility index was found to be predictive of mortality in PAH and may be a valuable marker for risk stratification. Its prognostic strength may be driven by mean right atrial pressure.

32-year-old with Paroxysmal Atrial Fibrillation after Traumatic Spinal Cord Injury.

A 32-year-old man presented with sudden loss of consciousness after passing urine with resultant trauma to the back of his neck. There were no palpitations prior. Examination revealed flaccid paralysis of all 4 limbs with priapism. Electrocardiogram demonstrated atrial fibrillation with rapid ventricular response. Laboratory showed normal potassium, magnesium, calcium, thyroid stimulating hormone and troponin I levels. Magnetic resonance imaging of the cervical spine demonstrated left C4 facet dislocation with grade 1 spondylolisthesis of C4 over C5, with moderate to severe narrowing of the spinal canal with cord compression and oedema. Transthoracic echocardiogram demonstrated an ejection fraction of 60% and no valvular abnormalities. Left atrium size was normal. The atrial fibrillation subsequently spontaneously reverted to sinus rhythm without treatment. Clinicians should be aware that atrial fibrillation can occur in the context of traumatic spinal cord injury due to disruption of the autonomic pathways in the cervical spine.

Pulmonary arterial hypertension in a multi-ethnic Asian population: Characteristics, survival and mortality predictors from a 14-year follow-up study.

BACKGROUND AND OBJECTIVE: Pulmonary arterial hypertension (PAH) is a rare and fatal disease. Data from Asia are lacking compared with the West. We aim to describe disease characteristics in an ethnically diverse South-East Asian population and assess predictors for survival. METHODS: We consecutively enrolled patients with PAH referred to our pulmonary hypertension specialty centre from January 2003 to December 2016. Baseline characteristics and survival were analysed. Based on a forward predictor selection procedure, a multi-level structural equation model was applied to identify predictors associated with mortality. RESULTS: Out of 148 patients enrolled, 77% were females and mean age was 50.8 ± 15.9 years. Racial distribution was consistent with our population census. The most common aetiologies were congenital heart disease-associated PAH (35.8%), idiopathic PAH (29.7%) and then connective tissue disease-associated PAH (24.3%). Most patients presented in World Health Organization (WHO) Functional Class (FC) II (48.6%), followed by FC III (28.8%). Majority of patients (54.1%) were on phosphodiesterase type 5 (PDE5) inhibitor monotherapy. Survival rates were 85.8% at the end of the first year, 70.9% at 3 years, 66.9% at 5 years, 61.5% at 7 years and 55.4% at 10 years. The Registry to Evaluate Early And Long-term PAH Disease Management (REVEAL) score (RS) was found to be the best predictor of mortality. A score > 6 was identified as a cut-off. Other predictors include mean right atrial pressure, heart rate, aetiology, age and N-terminal pro-brain natriuretic peptide. CONCLUSION: In this first registry study from a South-East Asian population, our survival rates are comparable with other national registries. The RS is validated in our population to be a good predictor of mortality.