Eight hundred twelve men with presumed acute myocardial infarction and left ventricular filling pressure of at least 12 mm Hg participated in a randomized double-blind placebo-controlled trial to assess the efficacy of a 48-hour infusion of sodium nitroprusside. The mortality rates at 21 days (10.4 per cent in the placebo group and 11.5 per cent in the nitroprusside group) and at 13 weeks (19.0 per cent and 17.0 per cent, respectively) were not significantly affected by treatment. The efficacy of nitroprusside was related to the time of treatment: the drug had a deleterious effect in patients whose infusions were started within nine hours of the onset of pain (mortality at 13 weeks, 24.2 per cent vs. 12.7 per cent; P = 0.025) and a beneficial effect in those whose infusions were begun later (mortality at 13 weeks, 14.4 per cent vs. 22.3 per cent; P = 0.04). Nitroprusside should probably not be used routinely in patients with high left ventricular filling pressures after acute myocardial infarction. However, the results in the patients given late treatment suggest that those with persistent pump failure might receive sustained benefit from short-term nitroprusside therapy.
The increasingly frequent use of continuous ambulatory peritoneal dialysis (CAPD) as substitutive therapy in terminal renal failure has induced the investigation of the advantages and disadvantages of this therapeutic modality. The effects of CAPD on pulmonary function are one of the aspects currently under study. Based on previous data suggesting the existence of extrapulmonary ventilatory restriction in uremic patients under CAPD, we have studied in these patients the respiratory muscle function as expressed in the maximal inspiratory pressure (MIP) and assessed the impact of the infusion of 2 liters of dialysis fluid into the peritoneal cavity on both MIP and the pulmonary volumes. Uremic patients evidenced significantly lower MIP values as compared with healthy controls. The filling of the peritoneal cavity induced, both in the supine and in the sitting position, a restrictive effect and an increase in the inspiratory capacity. We conclude that uremic patients under CAPD evidence a respiratory muscle dysfunction of as yet unclear cause. Our findings further suggest that the infusion of 2 liters of dialysis fluid into the peritoneal cavity induces not only a restrictive effect, but also an increase in the strength of the respiratory muscles, the latter effect being probably due to increased diaphragmatic contractility.
THE value of observations made during exercise in assessing the severity of isolated pulmonic stenosis has been recognized previously.1-4 Elowever, the small number of patients studied, the coincident occurrence of right-to-left shunting, and the paucity of comparable data in normal subjects have made for difficulties in interpretation. As a more precise assessment of the severity of pulmonic stenosis became necessary with the development of surgical technics for correction, exercise response was emphasized by Brock.5 The need for evaluating the rise of right ventricular systolic pressure during exercise in the selectioin of patients for surgery was stressed, and Johnsoin(" pointed outt its importance in the appraisal of the results of valvotomy.The ptirpose of this report is to present observations on the circulatory response to) exercise in a selected group of adult subjects with isolated pulmonic stenosis by uise of a technic f.or simultaneous measurement of pulinonary arterial and right ventricular pressures, and the Fick principle method for determination of cardiac output.
Materials and MethodsAll patients studied were subjected to careful examination to exclude congenital cardiac anomalies other than pulmonic stenosis with intact ventricular septum. In addition to clinical examination, this included ani electrocardiogram, chest teleroentgenogram, and right heart catheterization. Particular attention was directed toward exclusion of subjects in whom intracardiac shunting mechanisms existed at rest or during exercise.
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