Venography was performed on fifty-six patients suspected of having deep venous thrombosis (DVT) of the legs. The accuracy of the D-dimer measurement in plasma using two latex tests and an enzyme-linked immunosorbent assay (ELISA) was compared with that of usual determination of total fibrin(ogen) degradation products (FDPs) in serum with respect to the presence of DVT. The three D-dimer tests were clearly superior to the FDP assay, but only the ELISA could accurately rule out the diagnosis of DVT with a predictive value of 100% when plasma D-dimer level was less than 200 micrograms/L. However, this test cannot be used for positive diagnosis (false positive rate of 69%). Thus, plasma D-dimer measurement with ELISA allows identification of patients in whom further investigation by means of more specific tests (venography or plethysmography) is indicated in order to establish the diagnosis of DVT. In contrast to this, sensitivity of the two latex tests studied was low (60 and 76%, respectively), which makes them unsuitable for emergency screening. In addition, the potential of D-dimer dosage for diagnosis of DVT in hospitalized patients is hampered by the presence of associated conditions that are responsible for elevated plasma levels in most cases.
The predictive value of the pedal transcutaneous oxygen tension (tcPO2) and of the distal systolic blood pressure (SBP) in forecasting the necessity for later amputation has been studied in 26 patients suffering from severe chronic ischaemia of the lower limbs. In all these patients vascular surgery had failed or not been possible, and they were threatened by amputation; they suffered from trophic lesions, or pain at rest, or both. The great toe SBP averaged 10 mmHg (range 0 to 60 mmHg) and the pedal tcPO2 10 mmHg (range 2 to 45 mmHg). After six minutes of oxygen inhalation there was an increase in pedal tcPO2 of 9 mmHg (0 to 50 mmHg). After a follow-up period averaging 7 months (range 10 days to 13 months), 13 patients underwent an amputation and nine (five of whom had been amputated) died. The great toe SBP in the patients who required amputation was initially lower than in those who did not. The pedal tcPO2 also was lower in amputated than in non-amputated patients. There was no amputation in the group showing an increase of at least 10 mmHg after six minutes of oxygen inhalation; and conversely, all patients in whom the pedal tcPO2 increased less than 10 mmHg were amputated. Thus increase in the pedal tcPO2 after oxygen inhalation appears the best criterion for estimating the prognosis of severely ischaemic limbs.
This study shows that peripheral venous flow detected by Doppler ultrasound becomes synchronously pulsatile with heart beats as soon as central venous pressure (CVP) is above 7 mm Hg. CVP was above 7 mm Hg in 13 among 46 patients. Clinical signs of right heart failure were detectable in only 7 of these 13 patients (sensitivity 54%), whereas peripheral venous flow was pulsatile in 12 of them (sensitivity 92%). In 4 patients with a normal CVP, peripheral venous flow was also pulsatile; all of them suffered from valvular heart disease with left ventricle ejection fraction below 60% in 3 of them. The detection of a pulsatile peripheral venous blood flow constitutes an early sign of right heart failure, more sensitive than clinical evaluation, and probably even more than CVP.
Pedal transcutaneous partial pressure of oxygen (tcPO2) has been measured by polarographic method, heating the skin at 44 degrees C. In 50 normal subjects, mean tcPO2 measured 54.5 +/- 7 mmHg. Among 43 patients suffering from chronic ischaemia of lower limbs, mean tcPO2 measured 40.8 +/- 8 mmHg in patients with from claudication and 16.1 +/- 15 mmHg in patients suffering from rest pain and/or gangrene. The variability of repeated tcPO2 measurements, expressed as 1 SD of the mean, was 4.5 mmHg in normal subjects and 2.9 mmHg in patients. The relationships between pedal subcutaneous blood flow measured in xenon-133 clearance method and pedal tcPO2 have been studied in nine normal subjects and in five patients suffering from severe chronic ischaemia of lower limbs (rest pain and/or gangrene). There was a positive correlation between blood flow and tcPO2 in normal subjects (r = 0.77, P less than 0.001). In patients suffering from severe ischaemia, there was no correlation between these two parameters, but measured blood flow was sometimes very high in areas where tcPO2 was low. It is likely that 133Xe clearance method considerably overestimates local blood flow in these patients, because there is considerably less fat in subcutaneous tissue of chronic severely ischaemic areas. Thus, partition coefficient should be determined in each patient. However, tcPO2 may constitute an index of nutritional circulation, while 133Xe clearance actually measures total subcutaneous blood flow.
Because cigarette smoking is a definite risk for the development of cardiovascular disease and nicotine induced vasoconstriction may be a possible pathogenetic factor the haemodynamic effects of smoking cigarettes with high or low nicotine content were compared with those induced by chewing nicotine gum in a placebo controlled, crossover study in six healthy volunteers. The three stimuli induced similar increases in heart rate (about 20%) and systolic blood pressure (about 7%) and a decrease in digital blood flow. Although the mean haemodynamic changes parallelled the mean plasma nicotine concentration increases, no correlation was found between them when the individual values were considered. It is concluded that the nicotine induced haemodynamic changes probably occur as a result of the (local) release of vasoactive mediators such as adrenaline or noradrenaline after a threshold plasma nicotine concentration has been reached. Such a threshold may explain the large interindividual variability in susceptibility to smoking induced cardiovascular diseases. blood with a possible decrease of the oxygen supply to the endothelial cell.' In the present study, we compared the haemodynamic response of young healthy smokers to three different nicotine stimuli: a cigarette with high or low nicotine content and a nicotine chewing gum. These three stimuli were compared with a placebo in a crossover study,8 and the induced haemodynamic changes were correlated with increases in the plasma nicotine concentration. Subjects and methods STUDY PROTOCOLSix healthy male smokers (mean(SD) age 30(2.8) years; mean(SD) cigarette consumption 8.2 (1.1) pack year, where 1 pack year corresponds to smoking 1 pack of 20 cigarettes per day during one year) were enrolled in a crossover, placebo controlled study. The trial was carried out according to the Declaration of Helsinki and was approved by the human ethical committee of our institution. The study consisted of 154
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