Luigi Marazzini

Detection of Circulating DNA in Plasma of Patients with Pulmonary Embolism by Counterimmunoelectrophoresis

In order to confirm the usefulness of free plasma DNA detection in the diagnosis of pulmonary embolism (PE), we have studied 16 patients with PE, 33 with various diseases, and 13 normal subjects. Free plasma DNA was detectable in 15 of 16 patients with PE (94%) and in 3 control patients, but never in plasma from normal subjects. In most cases, DNA was detectable until the 10th day after PE. In conclusion, counterimmunoelectrophoresis is a rapid, inexpensive and specific test which may be used as an exclusion test in the detection of patients suspected of having PE, who will have to undergo more extensive evaluation.

Effects of Isovolumetric Venesection on Blood Viscosity, on Red Cell Deformability, and on Arterial Flow Velocity in Chronic Respiratory Failure with Secondary Polycythemia

Normovolemic hemodilution produced by isovolumetric venesection was done in 8 patients with polycythemia and respiratory failure secondary to chronic obstructive pulmonary disease. The deformability index was studied by means of a filtration technique. The blood flow velocity in ascending aorta and right pulmonary artery was also studied by means of ultrasonic Echo-Doppler technique. The procedure showed in all patients an increase of oxygen tension and a decrease of carbonic gas tension in arterial blood. At the same time it was possible to demonstrate an improvement of red cell deformability and an increase of arterial flow velocity. Isovolumetric venesection is an important procedure in the management of patients with polycythemia secondary to respiratory failure.

Effect of Hematocrit on the Blood Viscosity of Patients with Chronic Respiratory Failure and Secondary Polycythemia

The blood of patients with chronic global respiratory failure and polycythemia exhibits higher viscosity than that of normal subjects. Plasma changes have been excluded as causal factors. The viscosity of whole blood, plasma and blood after correction of hematocrit (Ht; 45%) with autologous plasma, has been determined. The results indicate that in such patients the increase in Ht is not the most important factor affecting the rheological properties (increased viscosity) of blood. A high Ht value may be only pat of the mechanism that increases the blood viscosity of patients with chronic obstructive pulmonary disease. There is evidence that other factors are responsible for increased blood viscosity in chronic respiratory failure.

Clinical Value of Rebreathing Test in Obstructive Lung Diseases

The ventilatory response to CO2 inhalation, using rebreathing method, was studied in normal subjects and in patients with bronchial asthma and chronic obstructive lung disease. The patients with lung disease had flatter CO2 response curves. However, it the ventilation was expressed as a fraction of the maximal voluntary ventilation, the difference between normal subjects and patients disappeared. The reduced ventilatory response of these patients may be of mechanical origin and not depending on reduced CO2 sensitivity. The high lung volume of these patients may be the mean factor of the mechanical disadvantage of thoracomuscular system.

Respiratory function 8 years after a diagnosis of peripheral airways disease.

A program of screening for airways obstruction was designed to examine: (1) the precision and the reliability of the proposed tests (2) the evolution of respiratory impairment in 69 subjects, 8 years after a diagnosis of peripheral (small) airways obstruction. The tests that exhibit very good reliability are: vital capacity, total lung capacity, 1-second forced expiratory volume, single breath CO diffusion capacity, curvilinearity score; and the ratio of closing capacity to total lung capacity. 39% of smokers and 15% of nonsmokers developed central airways obstruction 8 years after the diagnosis of peripheral airways disease. These results confirm the hypothesis that small airways may be regarded as a noisy rather than a silent zone.

Drive and Performance of Ventilatory System during Rebreathing

In eight normal subjects, eight patients with asthma, and six patients with chronic obstructive lung disease, the first derivative of occlusion pressure at FRC during rebreathing has been studied. The maximal dP/dt was always lower in patients. Such a behavior may depend on reduced neuronal discharge as well as on reduced effectiveness of the contraction of the respiratory muscles. Though (dP/dt)max. may provide a reliable measure of the sensitivity of the respiratory center only in a homogeneous group, the results of plotting its value against ventilation and end-tidal Pco2 confirm the failure of the thoracomuscular system to convert the output of respiratory centers into increase of pulmonary pressure and ventilation.

Autoconsistency in Ventilatory Mechanics

We test the reliability of a generalization of the electric network scheme in ventilatory mechanics, using as input a set of compartments derived from washout curves and compar- ing output with effective compliance, resistance and cumulative phase lag between applied pressure and volume inflation

Dynamics of the Maximal Contraction of the Respiratory Muscles in Chronic Obstructive Lung Disease

In seven normal subjects and in seven subjects with obstructive lung diseases, the kinetics of respiratory pressure changes produced by the respiratory muscles during the quickest and maximum static e