Asunto(s)

RESUMEN

The reliability and accuracy of the bolus injection-dye dilution technique were assessed for a physiological range of frequencies (13-49 min-1) and stroke volumes (60-160 ml) on a glass model where flows and volumes varied as a preset function of time (n = 320). We found that the technique overestimates flow by about 8% with a 95% confidence interval of +/- 10% for one measurement. Mean transit times are accurate within a +/- 7% confidence interval for one measurement. In a time-dependent flow and volume system this technique measures the mean volume as related to time with fluctuations up to +/- 30% around the mean. Results are independent of time and site of injection. The double injection-single sampling technique gives results that are equivalent to those obtained by single injection and sampling of dye.

Asunto(s)

RESUMEN

Ventilation of the lungs using Xenon 133 and perfusion scans using 99m Tc albumin particles in microspheres were performed on 455 patients with bronchial cancers and 55 patients with pulmonary metastases. Ventilation-perfusion mismatch and functional defects of the lung, which are never found in nodular-shaped pulmonary metastases, vary in frequency according to the anatomo-pathological type of the tumor and constitute a limiting factor for ablation.

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

Pulmonary vascular pressure, blood flow, and blood volume were measured in the supine and sitting positions in eight subjects with localized lung carcinoma associated with moderate airway obstruction. Supine cardiac output, pulmonary wedge (Ppw) and artery (Ppa) pressure, and pulmonary vascular resistance (PVR) were normal. Circulatory changes in sitting position were also normal: heart rate increased 13 +/- 9% (mean +/- SD); stroke volume fell 21 +/- 15%; cardiac output fell 13 +/- 19%; and arteriovenous O2 difference increased 37 +/- 21%. Neither the difference between mean Ppa and mean Ppw nor the rise of PVR from 92 +/- 25 to 122 +/- 49 dyn.s.cm-5 in sitting position were significant. Pulmonary blood volume (PBV) as measured by a dye-bolus-injection technique fell from 517 +/- 122 ml supine to 360 +/- 43 ml sitting (P less than 0.01). This decrease is best explained by closure of alveolar vessels in the upper part of the lung and by the concomitant cessation of flow in corresponding extra-alveolar vessels, which would prevent distribution of dye in the region. Circumstantial evidence suggests the latter vessels remain open under the large expanding stresses that prevail in the upper lung.

Asunto(s)

RESUMEN

The risk of incorporating inapparent recirculation under the extrapolated downslope of dye dilution curves is greater with exponential than gamma function extrapolation since the latter makes use of ascending and early descending limbs of the curve. Extrapolation of a true gamma function is not affected by the level at which extrapolation begins. With curves obtained in eight normal subjects, cardiac output (phi) was comparable by exponential and gamma extrapolation if the latter began between 75 and 55% of the peak concentration (Cmax.). phi was underestimated or overestimated according to whether extrapolation began higher or lower than the above limits. Therefore, experimental curves were not true gamma functions. However, the level at which extrapolation began had little effect on pulmonary mean transit time and pulmonary blood volume (PBV) calculated by use of the double injection-single sampling method. Similar effects on phi of the level at which extrapolation by a gamma function begins were found with 24 chronic bronchitics. PBV calculated with a gamma function extrapolated from 0.75 X Cmax. downwards and with an exponential function averaged approximately 340 ml and did not differ from one another. The data suggest that the low values of PBV in chronic bronchitis are not an artifact due to the method of extrapolation.

Asunto(s)

RESUMEN

An impairment of gluconeogenesis has been proposed to explain the low arterial blood glucose of highlanders. Therefore, we studied splanchnic blood flow, splanchnic uptake of oxygen and lactate, and output of glucose in nine normal and six anemic highlanders at an altitude of 3,750 m. Splanchnic blood flow, arteriovenous difference for oxygen, and oxygen consumption were comparable at rest in both groups and in lowlanders from the literature, whereas splanchnic output of glucose, and uptake of lactate were approximately twice those in lowlanders. After 10 min of mild exercise in 12 subjects (7 normals, 5 anemic), no significant changes in splanchnic hemodynamics and metabolism were found. During 29% oxygen breathing in 8 subjects (5 normals, 3 anemics), arterial lactate, splanchnic uptake of lactate and output of glucose fell to normal sea-level values. We concluded that splanchnic hemodynamics are similar in adapted highlanders and in lowlanders, and that there is no evidence of an impaired gluconeogenesis at the altitude of the present study.

Asunto(s)

RESUMEN

In a series of 40 cases of lung cancer, we recorded arterial dilution curves before and after unilateral occlusion of the pulmonary artery (on the pathologic side) following injection of dye into the pulmonary arterial trunk ("arterial curves") and in the capillary wedge position ("capillary curves"). In one case, a large pulmonary collateral circulation (PCC) is obvious, i.e., the dilution curve shows the characteristic shape of an early recirculation before and a normal shape after occlusion. In three cases, the PCC is likely to exist for: 1) decreasing of the capillary curves is abnormally slow during control; 2) transit time of capillary curves is obviously longer during control; 3) the surface under the arterial curve is 9 to 20 % larger during control than during occlusion. This surface undoubtly corresponds to the first dye circulation during pulmonary artery occlusion while, during control, it is increased by the PCC inspite of the exponential shape of the decreasing slope. Therefore the dye dilution method cannot be used to calculate precisely the PCC flow. Practically, in lung cancer measurements of the cardiac flow by dye dilution curves is erroneous about once out of 10 times. This conclusion can be extended to other lung diseases where a PCC may develop.

Asunto(s)

RESUMEN

Pulmonary vascular pressures and blood flow were measured with and without unilateral pulmonary arterial occlusion (UPAO) at rest and during exercise in 10 normal highlanders at La Paz, Bolivia (altitude, 3,750 m). In 6 other highlanders at rest and during exercise, pulmonary pressures, flow, and blood volume were measured during air breathing (PIO2 congruent to 100 Torr) and 29-30% oxygen (PIO2 congruent to 150 Torr). During air breathing, pulmonary vascular resistance was elevated at rest and did not change with exercise. Pulmonary arterial pressure rose less at rest with UPAO than during exercise without UPAO, and pulmonary vascular resistance was less in the former. Raising PaO2 to normal sea-level values had no effects on the pulmonary circulation at rest but prevented to a large extent the rise in pulmonary arterial pressure during exercise. Hence pulmonary vascular resistance during exercise was lower with oxygen than without. Thus, hypoxic vasoconstriction contributed to the pulmonary hypertension during exercise in normal highlanders. Circumstantial evidence suggests that this is related to the profound mixed venous hypoxemia caused by exercise in a hypoxic environment.

Asunto(s)

RESUMEN

We propose a simplification of the double-injection method whereby left atrial catheterization is made unnecessary by use of injection of indicator in the pulmonary wedge position instead of into the left atrium. Normal values of PBV range between 204 +/- 51 ml. m-2 and 326 +/- 51 ml. M-2. Such a large scatter is due in all likelihood partly to techniques themselves, partly to the small number of studied subjects, which precludes standardization of normal values according to age, sex and body build. Determination of PBV may help in assessing the overall distensibility of the pulmonary vascular bed, but is of no avail to assess separately the distensibility of arteries, microcirculation, and veins whose respective volumes cannot be measured in vivo for lack of undisputable methods. Morphometric and physiological observations suggest that the measurement of PBV is no avail to estimate changes in caliber of pulmonary arterioles caused by vasoactive stimuli.

Asunto(s)

Asunto(s)

RESUMEN

The pulmonary blood volume (Q) can be measured by dye injection in the pulmonary artery (PA) and in the left atrium (LA) and by sampling in the brachial artery (double injection - single sampling method). We propose to replace the injection in the LA, for which a left heart catheterization is needed, by a pulmonary wedge injection (PW). No significant difference was found between the first and the second method in twenty-four measurements in six anesthetized and artificially ventilated dogs kept in steady hemodynamic state : QPW (1) equals 0.009 + 1.106 QLA (r equals 0.935). The results are independent of the capillary injection site. In man, the indirect validation was made by unilateral occlusion of a main pulmonary artery, allowing blood volume measurement of the occluded lung by two methods, one of them independent of the "capillary" injection. The results of both methods are comparable and highly correlated (r equals 0.86). The range of the values of pulmonary blood volume in sixteen normal supine subjects, at rest, was similar to that of other authors, whichever the technique they used (394 plus or minus 114 ml, 268 plus or minus 59 ml m-2). The reproducibility of the results was comparable. In five subjects, pulmonary blood volume did not change during a moderate muscular excerise in the supine position (57 watts). The pulmonary wedge injection in man can replace the LA injection of the double injection - single sampling method, without loss of precision nor effect on reproducibility.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)