[Continuous positive airway pressure : a therapy for life]. / Pression positive continue: un traitement pour le long terme.

The treatment by continuous positive airway pressure (CPAP) corresponds to the application of a pneumatic splint to remove the collapses of the air routes higher at the origin of the apnea during the sleep. The CPAP is transmitted to the patient by means of an interface. The effectiveness of the device is recognized in the treatment of symptomatic sleep apnea syndrome (SAS) with the disappearance of diurnal sleepiness. A prolonged therapy is necessary to consider effect beneficial, with the help of an observance which exceeds the 4 hours per night. The side effects are related on the mask and the continuous flow which irritates the mucous membranes, but they are easily controllable. The assets of the CPAP in the reduction of the cardiovascular events still makes debate, even for the durable control of arterial hypertension. The annual cost of the CPAP therapy remains high.

Model for ion injection into a quadrupole ion trap to assess the distribution of initial conditions of confinement.

A pulsed ion-injection mode for a quadrupole ion trap is described. Switched direct current (d.c.) potentials are applied to the source and trap electrodes to inject the ions into the trap and slow them down. The injection time is sufficient to ensure a steady distribution of the injected ions at the beginning of the confinement. An elementary uni-dimensional model is detailed giving the axial positions and velocities of the ions injected into the trap. The ion distribution in phase space, the number of injected ions and the number of injected ions that will be trapped are also given. These expressions depend on ion position and velocity at the creation, applied potentials and spatial location of the source and trap electrodes. This model is validated by comparing simulation and experimental results. For this purpose the number of confined ions is plotted versus the slowing-down potentials applied on the ring and the upper end-cap of the trap. The size of the area of removable ions in the source is deduced from these results.

[Platypnoea and orthodoexia syndrome, a rare cause of dyspoea]. / Une cause rare de dyspnée et d'hypoxémie: le syndrome de platypnée-orthodéoxie.

Platypnoea-orthodeoxia is a rare syndrome of postural hypoxaemia accompanied by breathlessness. The dyspnoea is induced by upright posture. The definitive diagnosis is usually made by contrast echocardiography. The treatment of choice is surgical closure of the intracardiac communication which may result in dramatic symptomatic improvement.

Amiodarone therapy for sustained ventricular tachycardia after myocardial infarction: long-term follow-up, risk assessment and predictive value of programmed ventricular stimulation.

We determine the value of the programmed ventricular stimulation (PVS) and of clinical, angiographic and electrophysiologic variables in assessing the long-term risk of arrhythmia recurrence in a group of coronary artery diseased patients presenting with a first episode of monomorphic sustained ventricular tachycardia (VT) treated with amiodarone. Mortality and arrhythmia recurrence rates were retrospectively assessed in 55 consecutive patients with previous myocardial infarction presenting with a first VT episode. Results of left heart catheterization, echocardiography and time-domain signal-averaging were collected. Patients underwent PVS after amiodarone oral loading and were classified according to inducibility before being all discharged on amiodarone (200 mg daily). The mean follow-up was 42+/-31 months. Total and cardiac mortality rates were 29% (16 patients) and 23% (13 patients) respectively. Sudden death (SD) occurred in nine patients (16%). VT recurred in 13 patients (23%). Sustained monomorphic VT was inducible in 40 patients (72%) after amiodarone loading. Neither total mortality (10/40 vs. 6/15) nor cardiac mortality (3/40 vs. 1/15) were significantly different between inducible and non-inducible patients. Recurrent VT rate was 27% (11/40 patients) for the inducible group and 13% (2/15 patients) for the non-inducible group (NS). SD occurred in 6/40 inducible patients (15%) and in 2/15 non-inducible patients (13%) (NS). Arrhythmic events occurred in 42% (17/40) inducible patients vs. 26% (4/15) non-inducible patients (P=0.07). Parameters correlated with outcome were ejection fraction (EF) (5 SD/11 patients with EF <0.3 vs. 4/44 with EF >0.3, P=0.003), mitral insufficiency (MI) (4 SD/10 patients with MI vs. 4/44 patients without MI, P=0.004) and age (65+/-9 years for patients with VT recurrence vs. 58+/-9, P=0.02). Although the risk stratification can be improved, reliable and safe long-term prediction of recurrence of malignant ventricular arrhythmia in individual patients cannot be made. Consequently, the systematic implantation of a cardioverter-defibrillator in case of a first episode of sustained VT occurring in coronary artery disease patients should be further debated.

Haemodynamic and endocrinological effects of noninvasive mechanical ventilation in respiratory failure.

The aim of this study was to investigate the haemodynamic and endocrinological effects of noninvasive positive pressure ventilation (NIPPV). Eleven patients with oedema and recent hypercapnic and hypoxaemic worsening of a chronic respiratory insufficiency were included. Echocardiography, cardiac radionuclide assessment, blood catecholamines, salt and water handling hormones were measured at admission and discharge (long study (LS)). To discriminate between the action of NIPPV and other treatments, measurements were performed on the fourth day, for 4 h without NIPPV and 4 h with NIPPV (short study (SS)). NIPPV entailed a correction of P(a,CO2) and an increase of P(a,O2) in LS and SS. Oedema disappeared. Body weight decreased (from 85+/-42 to 81+/-40 kg) during LS. Systolic and mean pulmonary arterial pressure decreased in LS and SS. Right ventricular ejection fraction increased in LS. Left ventricular ejection fraction did not change. Cardiac index was normal on admission and then decreased. Natriuretic peptides and catecholamines were increased on admission, whereas plasma renin activity, aldosterone and vasopressin were normal. We suggest that in these patients, oedema can occur independently of renin-angiotensin-aldosterone-vasopressin and with a normal cardiac output. Noninvasive positive pressure ventilation allowed a correction of blood gases, associated with the resolution of oedema, a decrease in pulmonary arterial pressures and an increase in right ventricular ejection fraction.

Kinetic analysis of thyroid hormone action on glucose metabolism in man.

Thyroid hormone action on insulin's effect on glucose kinetics was investigated with the use of a physiological three compartment model. In six healthy volunteers before and after 14 days of thyroxine treatment (300 micrograms/day), a bolus of [3-H3]glucose was injected and the time course of plasma radioactivity was followed closely for 150 min. Then a hyperinsulinemic (1 mU.min-1.kg-1) and euglycemic clamp was started, and euglycemia was maintained for another 250 min. A second bolus of the tracer was then given at 240 min, and the plasma radioactivity was followed for 160 min. Insulin stimulated basal plasma glucose clearance fourfold (p < 0.001) and completely suppressed basal hepatic glucose production (p < 0.001). Concomitantly, the total distribution volume of glucose was increased by 19% (p < 0.05); this change was accompanied by about 50% expansion of the slowly exchanging glucose pool (putatively representing the insulin-dependent compartment). Thyroxine treatment increased plasma triiodothyronine by about 20% (0.1 > p > 0.05) but did not affect basal glucose turnover, insulin-stimulated plasma glucose clearance or the insulin-induced suppression of endogenous glucose output. However, thyroxine treatment blunted the insulin-induced increases in total distribution volume and the slowly exchanging pool of glucose (p = NS vs the basal state). We conclude that minor changes in plasma triiodothyronine (such as occur during overfeeding) do not interfere with the ability of insulin to stimulate the rate of disappearance of glucose or suppress endogenous glucose release; however, our data suggest that they induce finer changes in glucose kinetics, possibly reflecting acceleration or intracellular glucose degradation.

[Role of thrombolysis in the treatment of cardiogenic shock following myocardial infarct]. / Place de la thrombolyse dans le traitement du choc cardiogène après infarctus du myocarde.

Of a total of 329 consecutive patients treated by thrombolysis with recombinant tissue-type plasminogen activator following myocardial infarction, 13 (4%) were in cardiogenic shock at the time of admission to hospital, and 4 others (1.2%) developed cardiogenic shock during their hospital stay. Overall hospital mortality for shock was high at 88% (15 of 17 patients), and shock was responsible for 57.6% (15 of 26) of all hospital deaths. Although several studies have shown that thrombolysis reduces the likelihood of cardiogenic shock developing after admission, our data confirm that it does not constitute effective treatment of established shock. More aggressive approaches, using thrombolysis together with angioplasty and mechanical ventricular assist devices, need to be evaluated.

[Idiopathic sustained ventricular tachycardia in the young adult with right bundle-branch and left axis deviation]. / Tachycardies ventriculaires soutenues idiopathiques du sujet jeune à type retard droit et axe gauche.

The authors report 4 cases of sustained ventricular tachycardia with right bundle branch block and left axis deviation morphology. These ventricular tachycardias which are usually sensitive to Verapamil are often mistaken for supraventricular tachycardia. However, they are a specific clinical, electrocardiographic and electrophysiological entity. The origin of the tachycardia is probably in the Purkinje fibres of the left posterior hemibranch of the His bundle. The mechanism is controversial: much evidence points to reentrant phenomenon, but, in the present state of our knowledge, triggered activity cannot be formally excluded.

Severe acute myocardial infarction during a staphylococcal septicemia with meningoencephalitis. A possible contraindication to thrombolytic treatment.

We report the first case of lethal intracranial haemorrhage complicating a treatment by rt-PA in a patient presenting with a simultaneous staphylococcal septicemia with meningoencephalitis and an acute myocardial infarction with cardiogenic shock. The presence of microvascular lesions in the central nervous system seems to be important risk factor for intracranial haemorrhage and we recommend extreme caution in the use of thrombolytic treatment in septicemic patients with acute myocardial infarction, particularly when neurological symptoms are present.

Association of thrombotic thrombocytopenic purpura and human immunodeficiency virus infection.

A 35 year-old HIV-positive male intravenous drug abuser developed thrombotic thrombocytopenic purpura (TTP) during the course of recto-sigmoiditis secondary to Shigella flexneri. Complete remission was achieved by aggressive treatment of a combination of plasma exchange, fresh frozen plasma infusion, continuous prostacyclin perfusion, p.o. administered aspirin-dipyridamol and intravenous injections of vincristine. During acute microangiopathy, an acquired type II von Willebrand disease was diagnosed. TTP is a newly-recognized hematologic manifestation of HIV-1 infection; endothelial damage by endotoxin during course of infection or by high serum levels of circulating immune complexes may be a causative mechanism of microangiopathy causing hemolysis and platelet consumption.

Observations on effects of a central stimulant drug (methylphenidate) in children with hyperactive behavior.

Ninety-eight hyperactive children, ages 6 to 12 years, have been treated with methylphenidate or placebo under double-blind conditions. Only one of the 48 children receiving placebo (2%) was judged to be a drug success. Seventy-nine percent of the 94 children receiving methylphenidate were judged to be drug success at the end of the 16-week trial period. A wide range of dosage (0.2 to 1.9 mg/kg) was required for optimum drug effects. Drug failures were due either to appearance of withdrawn, apathetic behavior in the child (6 cases) or lack of evidence of drug effectiveness (14 cases). Overweight children did not respond well to medication even though milligram per kilogram dosage was equivalent to that in children who were categorized as drug successes. The most dramatic successes were seen in children who might be characterized as exhibiting "developmental hyperactivity," i.e., hyperactivity in the absence of other evidence of neurological or emotional disturbances. We conclude that a trial of stimulant drugs is clearly indicated in hyperactive children manifesting significant impairment of educational and social progress. Dosage adjustment and judgement of drug success or failure require regular reports from teachers and parents.