Detection of restenosis after successful coronary angioplasty: improved clinical decision making with use of a logistic model combining procedural and follow-up variables.

A prospective study of 111 patients who underwent repeat coronary angiography and exercise thallium-201 scintigraphy 6 +/- 2 months after complete revascularization by percutaneous transluminal coronary angioplasty was performed to assess whether clinical, procedure-related and postangioplasty exercise variables yield independent information for the prediction of angiographic restenosis after angioplasty. Complete revascularization was defined as successful angioplasty of one or more vessels that resulted in no residual coronary lesion with greater than 50% diameter stenosis. Restenosis was defined as a residual stenosis at the time of repeat angiography of greater than 50% of luminal diameter. Restenosis occurred in 40% of the patients. The 111 patients were randomly subdivided into a learning group (n = 84) and a testing group (n = 27). A logistic discriminant analysis was performed in the learning group and the logistic model was used to estimate a logistic probability of restenosis. This probability of restenosis was validated in the testing group. In the learning group of 84 patients univariate analysis of 39 factors revealed 8 factors related to restenosis: recurrence of angina (p less than 0.0001), postangioplasty abnormal finding on exercise thallium-201 scintigram (p less than 0.0001), exercise thallium-201 scintigram score (p less than 0.0001), difference between exercise and rest ST segment depression (p less than 0.001), postangioplasty exercise ST segment depression (p less than 0.001), absolute postangioplasty stenosis diameter (p less than 0.003), postangioplasty exercise work load (p less than 0.03) and postangioplasty exercise heart rate (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics, thrombolytic efficacy and hemorrhagic risk of different streptokinase regimens in heparin-treated acute myocardial infarction.

The systemic activator activity of 4 streptokinase (SK) regimens (250,000 IU intracoronary, group A; 500,000 IU, group B; 1.5 X 10(6) IU, group C; and 30 U anisoylated plasminogen streptokinase activator complex (APSAC) intravenously, group D) was tested with the fibrin plate technique. One hour after initiation of treatment, the activator activity was highest after APSAC (3.6 +/- 0.9 U), slightly but not significantly less after SK 1.5 X 10(6) IU (3.0 +/- 0.7), and significantly less after SK 500,000 IU (1.6 +/- 0.5) and 250,000 IU (0.6 +/- 0.5), p less than 0.001. After SK, activator activity half-lives were 184 minutes (group B) and 169 minutes (group C), and after APSAC 188 minutes (group D). These were all in agreement with greater than 12 hour duration of changes in other markers of systemic fibrinolysis (euglobulin lysis time) and substrates depletion (fibrinogen, plasminogen, alpha 2 antiplasmin). In extended pilot clinical groups given identical thrombolytic regimens during full anticoagulation with heparin, angiographic coronary patency was found in 83% (35 of 42) after intracoronary SK (group 1), in 73 and 75%, respectively, after 500,000 IU (31 of 43) and 1.5 X 10(6) IU (30 of 40) (group 2 and 3, difference not significant) and 80% (8 of 10) after the 30-U bolus of APSAC (group 4). The overall hemorrhagic risk was 24%, equally distributed among the 4 regimens and mostly (91%) related to catheters. The incidence of bleeding unrelated to vessel puncture was 4%; no deaths occurred. It is concluded that APSAC is the most fibrinolytic regimen but its potential thrombolytic superiority over SK remains to be demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Design of an automated system for assessing metabolic function in mechanically ventilated patients.

This paper describes the design of a fully automated self calibrated measurement system which can be connected to any commercial ventilator. The machine measures the oxygen consumption and carbon dioxide production. The instrument is based on commercially available analysers. An inexpensive microprocessor performs the computations, displays the results and leads the calibration's and measure's procedures. The apparatus is presently tested in clinical practice.

Measurement of flow in large veins by the continuous thermodilution method.

Simple methods for measuring percutaneously blood flow in veins characterized by a large oscillatory component of flow are lacking. Therefore, a thermodilution technique with a constant infusion rate was used for the measurement of inferior vena cava flow in anesthetized dogs. The accuracy of the method was studied both in an artificial circuit and in in vivo experiments. The thermal catheter was introduced upstream in a flow of water ranging from 50 to 1,200 ml/min produced in an artificial circuit maintained at 37 degrees C. With a volume of cold injectate of 43 ml/20s, the correlation between the values obtained by direct measurement and by thermodilution technique was highly significant (r = 0.993; n = 37) with a slope practically equal to 1.0 (Y = 1.03 X + 2.42). With the thermal catheter introduced through the jugular vein and an electromagnetic flowmeter probe placed around the exposed vessel, volumetric flows were registered in the subhepatic vena cava, infrarenal vena cava, as well as renal and iliac veins of eight dogs. Comparison of the values obtained by the two techniques yielded a regression equation of Y = 0.96 X + 34.31 with a correlation coefficient r = 0.943 (range 50-1,000 ml/min; n = 40). The continuous injection method was as accurate at low flows as at high. Qualitatively, thermodilution curves were comparable to electromagnetic flowmeter curves, reproducing instantaneously the cyclic respiratory variations. The method is thus particularly suitable for use in those veins in which there is a large oscillatory component of flow.

[Effect of positive end expiratory pressure on the intrapulmonary shunt and the oxygen alveolo-arterial difference in adult acute respiratory distress]. / Effet de la pression positive en fin d'expiration (P.P.F.E.) sur le shunt intra-pulmonaire et sur la différence alvéolo-artérielle en oxygène [P(A-a)O2] dans la détresse respiratoire aiguë de l'adulte (D.R.A.A.).

The aim of this study was to analyse two groups of 10 patients with hypoxaemia. One group of patients had acute respiratory distress (A.R.D.A.) and the other group was hypoxaemic without acute adult respiratory distress. Both group of patients were ventilated artificially. The authors studied the effect of positive end expiratory pressure (PEEP) of 10 cm H2O on the intra-pulmonary shunt (Qs/Qt) and on the alveolar-arterial oxygen difference [P(A-a)O2]. The values for the shunt and for P(A-a)O2 are calculated at FiO2 of 0.4 and at a FiO2 of 1. The two groups are best distinguished by the difference between the shunt calculated at a FiO2 of 0.4 and at a FiO2 of 1, as the P(A-a)O2 is similar in both groups of patients and is not influenced by the PEEP, either in the A.R.D.A. or in the non-A.R.D.A. group. Without PEEP, A positive value is obtained for Qs-Qt in the A.R.D.A. group and a negative value is obtained in the non A.R.D.A. group. With PEEP of 10 cm, the shunt in patients with A.R.D.A. is greatly reduced and tends towards 0. In the non A.R.D.A. group of patients, the shunt does not vary with the PEEP and the difference remains negative.

[The adult respiratory distress syndrome. Clinical signs, radiology and biological data (author's transl)]. / Détresse respiratoire aiguë de l'adulte. Signes cliniques, radiologiques et biologiques.

The etiology of shocklung is diverse. All causes lead to a lesion of the alveolar-capillary membrane with interstitial and subsequent alveolar edema. The clinical manifestations, although variable, are progressive and can be divided into 3 stages, which are the expression of a decrease in pulmonary compliance and of hypoxemia due to a ventilation-perfusion defect (shunt effect). The diagnosis of shocklung must be differentiated from pulmonary edema of cardiac origin by right heart catheterization and demonstrate a normal capillary pressure, a pulmonary hypertension with increased pulmonary resistance and a normal or increased cardiac output. A decreased PaO2 is the first sign of a ventilation-perfusion imbalance. The problem of alveolar-capillary O2 transfer is better defined by the alveolar-arterial O2 difference, the calculation of quantity of the intrapulmonary shunt and the hyperoxia curve. The daily analysis of the hyperoxia curve allows for a better appreciation of the clinical status than the clinical and radiological signs. The prognosis of the shockening is poor inspite of better reanimation technics. The mortality is about 50% and depends on 3 factors: etiology, early diagnosis and correction of the primary insult.

Microbial colonization of indwelling central venous catheters: statistical evaluation of potential contaminating factors.

A prospective study of 390 indwelling central venous catheters placed by way of the subclavian route identified bacteremia and tracheostomy as the only significant variables associated with the colonization of the catheters by pathogenic microorganisms. Catheter-related sepsis was likely in only 3 of 33 episodes of proved bacteremia. Detailed statistical analyses of other potential contaminating factors revealed no significant correlations.

Tracheostomy and indwelling central venous line: a hazaradous combination?

A prospective study of 390 indwelling central venous catheters placed via the subclavian route defined bacteremia and tracheostomy as the only significant variables associated with the colonization of the catheters by pathogenic microorganisms. Catheter related sepsis was likely in only 3 of 33 episodes of proven bacteremia. Detailed statistical analyses of other potential contaminating factors revealed no significance. Specific concern must be assigned to placement of central venous catheters by the subclavian approach, when a tracheostomy is already present,