Sonography of hypertrophic pyloric stenosis: frequency and cause of nonuniform echogenicity of the thickened pyloric muscle.

In hypertrophic pyloric stenosis, the muscle is typically described as hypoechoic on sonography. However, we have frequently noted a nonuniform pattern; the pyloric muscle seen in the transverse plane is more echogenic in the near and far fields and less echogenic on the sides. The muscle also appears almost as echogenic as the liver on midline longitudinal sonograms. To establish the frequency of these findings, we reviewed the sonograms of 71 infants with hypertrophic pyloric stenosis. The muscle was imaged directly during surgery in three patients. In an in vitro experiment, muscle arranged to stimulate the pyloric ring was scanned in a water bath. Then, using two sections of muscle, we compared the echogenicity when scanning in a plane perpendicular to the long axis of the muscle fibers with that seen with the beam parallel to the long axis of the muscle fibers. In the transverse plane, nonuniform echogenicity of the pyloric muscle was seen in 59 (98%) of 60 patients. In the midline longitudinal plane, the muscle was equal to or slightly less echogenic than the liver in all patients. Both the in vivo and in vitro studies show that the echogenicity varies with the relationship of the ultrasound beam to the orientation of the circular muscle fibers; this phenomenon is known as the anisotropic effect. Our results show that nonuniform echogenicity of the hypertrophied pyloric muscle is a characteristic sonographic finding caused by the anisotropic effect, which is related to the orientation of the ultrasound beam with respect to the circular fibers of the pyloric muscle.     

Pressure/flow relation in the peripheral pulmonary vascular bed in dogs: a preliminary study.

In order to test a technique for the determination of the pressure/flow relationship in the peripheral pulmonary vascular bed, the perfusion pressure changes with increasing and then decreasing flow in a small part of the lung (around 1 ml) were studied in anaesthetized supine dogs, after insertion of a specially designed double distal lumen Swan-Ganz catheter. One lumen was used for the pressure measurement, one for infusion of saline by a pump with variable flow, from 0.1 to 1.0 ml s-1. A conventional thermodilution Swan-Ganz catheter was also advanced in the pulmonary artery, to measure pressures in the pulmonary circulation as well as cardiac output. During infusion in the wedged catheter, right atrial, pulmonary arterial and balloon occlusion wedge pressures did not change. The pressure/flow curve of the occluded vascular bed showed a shape similar to that of collapsible tubes, with a pressure plateau at high flow, but this could also be due to vascular recruitment. The curve exhibited hysteresis, with a lower pressure when flow decreased. The slope of the initial part of the curve increased, on average, from 54 +/- 9 during normoxia to 91 +/- 27 mmHg s ml-1 during hypoxia (FIO2 = 0.10); this difference was not significant, but the perfusion pressure at high flow was significantly higher during hypoxia (P less than 0.05). Using blood instead of saline would allow the determination of the peripheral pulmonary vascular resistance under physiological conditions, and further work is needed to estimate the sensitivity and the reproducibility of this technique.     

A planar slab bidomain model for cardiac tissue

A fully three-dimensional model of the ventricular or atrial free wall will involve a planar geometry of finite thickness. The governing equations for the interstitial and extracellular potential of a planar slab of cardiac tissue comprised of parallel fibers undergoing uniform plane-wave activation are presented. A comparison with a bidomain of cylindrical geometry with the same half-thickness shows that the potentials in the planar bidomain (as a function of depth) approach core-conductor behavior more quickly.     

Effect of resistive discontinuities on waveshape and velocity in a single cardiac fibre

A computer model of a one-dimensional cardiac fibre of resistively coupled cells is used to investigate the influence of the junction resistance on the nature of conduction. The results of the simulations are presented and indicate that the effect of the junction on both intracellular and extracellular waveshape and on the velocity of propagation depends on the size and frequency of the coupling resistance and the kinetics of the active membrane. Significant changes in these factors are not observed without the generation of prepotentials in the action potential upstroke. The absence of this ‘signature’ in microelectrode recordings of activity in ventricular muscle suggests that under normal conditions cardiac tissue behaves as a functional syncytium.     

Recent advances in diagnosis and management of pulmonary hypertension in chronic lung disease

Pulmonary hypertension with elevated pulmonary vascular resistance is a common cardiovascular complication associated with increased morbidity and mortality in preterm infants with chronic lung disease. Injury to the developing pulmonary circulation results in structural and functional abnormalities of the pulmonary vasculature. Animal studies have demonstrated that disruption of angiogenesis may contribute to the failure of normal alveolarisation in chronic lung disease. Levels of vascular endothelial growth factor in bronchoalveolar lavage fluid are lower in infants with chronic lung disease compared to preterm controls. Supplemental oxygen is commonly used to prevent and treat pulmonary hypertension, although optimal arterial oxygen saturation levels remain uncertain. Other vasodilators such as inhaled nitric oxide appear promising, but as yet have not been evaluated in the form of randomised controlled trials. Further studies are required to investigate the long-term effectiveness of pulmonary vasodilator therapy.     

Relationship of Quality of Life with Disability Grade in Obsessive Compulsive Disorder and Dysthymic Disorder

Background:

There is paucity of information on the relationship of quality of life (QOL) in obsessive compulsive disorder (OCD) and dysthymic disorder (DD) with disability grade in India.

Aim:

To assess the relation of QOL with disability level in OCD and DD.

Materials and Methods:

This hospital based study was conducted in a medical institution in Davanagere, Karnataka, India. Data was collected by using Diagnostic and Statistical Manual IV Text Revision (DSM IV TR) criteria, WHO QOL BREF and IDEAS. Relationship between disability grade and QOL was assessed by independent sample t test.

Results:

Mild disabled OCD patients had a significantly better QOL in the Q1 domain i.e. perception on quality of life as compared to moderately disabled patients (P < 0.05), while in other domains of QOL, there was no statistically significant difference (P > 0.05). But, QOL score in physical domain showed significant difference across disability grades (56.00, SD = 6.89; 48.50, SD = 12.28) in DD, but not in other domains.

Conclusion:

Perception of QOL is better in those with mild disability in OCD, but in DD, physical domain of QOL score is more in mild disability compared to moderate disability.     

Cause of the raised wedge pressure on exercise in chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) markedly increase their pulmonary artery wedge pressure on mild exercise even though they have no overt left heart disease and no increase in the esophageal pressure (as a reflection of mean intrathoracic pressure). We wondered if lung distension due to gas trapping during the hyperpnea of exercise might cause the wedge pressure to rise by increasing juxtacardiac pressures above esophageal pressures. If this were so, then (1) tachypnea alone, without exercise, should cause the FRC and intracardiac pressures to increase in patients with COPD, (2) there should be an increase in FRC associated with the rise in wedge pressure on exercise, and (3) these changes should not occur in patients without COPD. We studied 39 patients with COPD (Ppa = 21 +/- 6 mm Hg [mean +/- SD], FEV1 [% predicted] = 39 +/- 16) and 13 control patients with similar pulmonary artery pressures but no airflow obstruction (Ppa = 22 +/- 20 mm Hg, FEV1 [% predicted] = 110 +/- 24). In those with COPD, light exercise raised the FRC by 0.5 +/- 0.5 L. Tachypnea alone, at the rate present during exercise, raised the FRC by 0.6 +/- 0.4 L and there was a 10% increase in left lower lobe area on lateral chest X-ray. Wedge, right atrial, and pulmonary artery pressures rose together during tachypnea with and without exercise. By contrast, in the control patients without COPD, the right atrial pressure change on exercise did not reflect that of the left atrium in extent or direction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative culture of bronchoalveolar lavage from patients with anaerobic lung abscesses.

The study of anaerobic infections of the lung is usually limited to the use of invasive techniques such as transtracheal aspiration (TTA) to avoid contamination by oral flora. Bronchoalveolar lavage (BAL) has been used successfully in the study of the etiology of pneumonia in immunocompromised patients. This study evaluated the role of the quantitative culture of BAL in the diagnosis of lung abscess. Four episodes of lung abscess in three patients were studied, and the results of quantitative culture of BAL were compared with those of the standard technique of TTA. Nineteen anaerobic bacterial species were recovered from the BAL fluid, all but one at concentrations greater than 10(3) cfu/ml. Culture of BAL fluid yielded 18 of 22 of the isolates cultured from TTA, including 12 of 16 of the anaerobic bacteria. This study suggests that quantitative culture of BAL fluid may be useful in the bronchoscopic evaluation of lung abscess.