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Biomedical subjects

B Rabinowitz

Publications and source records attributed to B Rabinowitz.

At least 55 records · Page 3Linked to original sources

Beneficial effect of magnesium sulfate in acute myocardial infarction.

The effects of magnesium on the incidence of arrhythmias and on mortality were evaluated in 103 patients with documented acute myocardial infarction (AMI) in a randomized, double-blind, placebo-controlled study. Fifty patients received a magnesium infusion for 48 hours and 53 received only the vehicle (isotonic glucose) as placebo. The baseline characteristics of the population were similar in the 2 groups. Tachyarrhythmias requiring drug therapy were recorded in 32% of the patients in the magnesium group and in 45% of the placebo group. Conduction disturbances were found in 23% of the placebo group as compared to 14% in the magnesium group. The intrahospital mortality was 2% (1 patient) in the magnesium group, compared to 17% (9 patients) in the placebo group (p less than 0.01). No adverse effects were observed during and after the magnesium infusion. These data support a possible protective role of magnesium in patients with AMI.

Aged

The influence of pH on the intravenous delivery of lidocaine solutions.

In order to evaluate the surface tension lowering effect of lidocaine 0.4% on a 5% glucose solution, drop size has been measured in intravenous sets of 60 drops per ml. The relationship between the number of drops per ml and the pH of the solution was sigmoidal, from 63 drops/ml at pH5 to 95 drops/ml at pH 10. Without lidocaine, the effect of pH on the drop count of the 5% glucose solution was negligible. The surface tension lowering effect of lidocaine may account for significant decreases in apparent bioavailability and delivered lidocaine when high pH solutions are used with drop counting infusion pumps.

Biological Availability

Repeat infusion of recombinant tissue-type plasminogen activator in patients with acute myocardial infarction and early recurrent myocardial ischemia.

When conventional treatment of patients with early clinical reinfarction after thrombolytic therapy fails, mechanical revascularization may be attempted. An alternative strategy, repeat thrombolytic infusions, is reported. Fifty-two patients with acute myocardial infarction were treated with one or two additional thrombolytic infusions of recombinant tissue-type plasminogen activator (rt-PA) because of nonsustained ischemia after initial treatment with rt-PA or streptokinase. Thirty-five patients received the second infusion within 1 h of the first; 13 patients received the second infusion 1 to 72 h after the first and 4 patients received it later during their hospitalization. Bleeding complications occurred in 10 patients (19%); however, most of these were minor (no intracranial bleeding) and only 2 patients required blood transfusion. In 14 patients in whom the decrease in fibrinogen and plasminogen levels was measured after the first and second infusions, this decrease was only 25% and 63%, respectively--only slightly higher than the 22% and 53% decreases measured in 63 patients who had only one rt-PA infusion. In 44 patients (85%), the acute ischemia resolved completely within 1 h after initiation of the second infusion. In 23 patients (44%), pain and ST segment elevation did not recur and invasive coronary intervention was avoided. Thus, repeat rt-PA infusions can stabilize a substantial number of patients with acute reinfarction and, even when relief is temporary, repeat rt-PA infusions can minimize myocardial damage while patients await mechanical revascularization.

Female

A reappraisal of prophylactic mastectomy.

The concept of prophylactic mastectomy was nurtured in the shadow of the radical mastectomy. It evolved as preferable to the mutilation caused by the procedure. It developed during a time when the difference between benignancy and malignancy was not as clear and when patients with benign disease were thought to be at significant risk. The idea of surgical prophylaxis accompanied by a superior cosmetic result, in comparison to the radical mastectomy is a noble one. In retrospect, however, it is clear that the indications were ill defined, based often on unfounded risk and predicated on patient and physician anxiety. The scope of risk in carcinoma of the breast has been narrowed, with new information identifying only specific subsets of women with proliferative types of benign disease as more susceptible to the subsequent development of carcinoma. Extensive reviews of material taken at biopsy that had been validated longitudinally have provided data to substantiate this contention. The concept of familial high risk must take into account the number of affected family members, at age diagnosis, menopausal status and bilaterality. The majority of indicants that motivated and propitiated the performance of the bulk of prophylactic mastectomies have lost their relevance. Prophylactic mastectomy for carcinoma, therefore, can perhaps be reserved for women with biopsy-proved, high-risk lesions or an exceptional familial risk, or both, or hereditary risk. Such women must choose for themselves and accept the uncertainty of hypothetic risk reduction, life-long continued surveillance and an altered body image. Guiding patients in the decision should involve a multidisciplinary team composed of a surgical oncologist, geneticist, pathologist, psychotherapist and plastic surgeon. As a concept, the reduction of risk is appealing, but remains yet to prove itself superior to rigorous clinical surveillance with high-quality mammography. The experience reflected in the literature of a seemingly low rate of subsequent carcinoma cannot be judged, because it seems that operations were applied indiscriminantly to patients selected by unknown means and from an unknown population pool. Success based on protecting those not at increased risk only invalidates the operation further. Most surgical and medical oncologists recognize that carcinoma of the breast is either localized or disseminated at the time of the initial diagnosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Breast Neoplasms

Influence of ethanol on the delivery of intravenous nitroglycerin solutions.

In order to evaluate the surface tension lowering effect of ethanol in intravenous nitroglycerin solutions of varying concentrations, drop size was measured in intravenous transfusion sets that should deliver 60 drops/ml. Ethanol 5% solutions led to a significant decrease in drop volume and a concomitant increase in the number of drops per unit volume, up to 79 drops/ml were observed. The surface tension lowering effect may account for decreases of up to 25% in delivered nitroglycerin when drop counting infusion pumps are used, and may be a factor in the development of apparent tolerance to intravenous nitroglycerin.

Ethanol

Haemodynamic effects of intravenous isosorbide-5-mononitrate in acute and chronic left heart failure of ischaemic aetiology.

Isosorbide-5-mononitrate was administered in a continuous intravenous infusion, according to the haemodynamic response, to 19 patients with left heart failure of ischaemic aetiology; 12 with acute heart failure complicating an acute myocardial infarction and 7 with chronic ischaemic failure. In both groups, the following statistically significant haemodynamic changes were observed: a decrease in PCWP from 25.4 +/- 4.6 to 17.2 +/- 4.6 mmHg; an increase in SWI from 19.1 +/- 10 to 23.6 +/- 13.1 gm m-2; a slight increase in cardiac index with no change in arterial pressure and only minimal decrease in vascular resistance. There were two major differences in the haemodynamic response between the patients with acute heart failure and those with chronic disease: (a) the duration of the effect of isosorbide-5-mononitrate on the PCWP was longer in the first group (mean, 8 hours, compared to 1.5 hours in the chronic group), and (b) the effect on afterload was more pronounced in the group with chronic ischaemic failure than in the first group. Thus, isosorbide-5-mononitrate administered by intravenous infusion under careful monitoring appears to have a beneficial role in the treatment of acute as well as chronic ischaemic heart failure.

Aged

The management of penetrating injuries of the back. A prospective study of 230 patients.

This is a prospective study of 230 patients with penetrating injuries of the back. The decision to operate or observe was taken exclusively on the abdominal physical findings. One hundred ninety-five patients (85%) did not require operation, 30 (13%) underwent a therapeutic laparotomy, four (1.7%) an unnecessary operation, and one patient (0.4%) had a completely negative laparotomy. The diagnosis and management was delayed in five (2.2%) patients with no serious consequences. Mortality rates were not recorded in this series. The initial physical examination was accurate in 95.2% of the patients. We suggest that penetrating injuries of the back should be assessed in the same way as anterior abdominal injuries. Physical abdominal examination is reliable in detecting significant intra-abdominal injuries.

Abdomen, Acute

Teaching social sciences in the clinical years through psychosocial conferences.

A program for teaching the social sciences in the clinical years in medical school is described. This program focuses on psychosocial conferences (PSC) held during the clerkships in internal medicine, pediatrics, and surgery. The aim of the PSC is the integration of the knowledge and skills imparted in the preclinical social sciences curriculum with the students' clinical experiences. PSC teaching includes tutorial guidance throughout the student's preparation of a case presentation in which psychological, sociological, and anthropological aspects of the patients' coping with illness and the patient-physician interrelationship are emphasized.

Clinical Clerkship

Hemodynamics, circulating catecholamines and response to intravenous nitrate therapy in a specific subset of acute myocardial infarction: the hypertensive-hyperkinetic-coronary-active group.

A specific subset of acute myocardial infarction was defined and named 'the hypertensive-hyperkinetic-coronary-active' subgroup. This subgroup included patients with acute myocardial infarction without pump failure or hypovolemia who continued to have hypertension and tachycardia, after relief of pain and who also had at least two recurrent ischemic episodes in the first days after a transmural event. Fifteen patients belonging to this group (group A) were studied in comparison with 15 other patients with acute myocardial infarction complicated by pump failure (group B). The alterations in hemodynamics, in circulating catecholamine levels and the clinical course during an intravenous infusion of isosorbide dinitrate were evaluated and the data obtained in the two groups were compared. The patients in group A had tachycardia, hypertension and upper normal filling pressures (pulmonary capillary wedge pressures: 15.8 +/- 1.8 mm Hg). They had high levels of circulating catecholamines (1,343 +/- 407 ng/l), a cardiac output of 5.9 +/- 0.6 liters/min and stroke work index of 78 +/- 11 (mean +/- SD). The effect of intravenous nitrates on the left ventricular function curves of the two groups was the following: a marked shift downward and slight shift to the left in group A, as opposed to a moderate but significant shift upward and marked shift to the left in group B. The episodes of recurrent ischemia subsided in 13 out of 15 patients from group A. It appears therefore that the hyperkinetic patients with acute infarction are characterized by a hypersympathetic response, a typical hemodynamic profile and a particular response to nitrate therapy directionally opposite to the changes obtained in patients with acute infarction complicated with failure.

Aged

Subclavian vascular injuries.

This study comprises 228 patients with penetrating injuries of the subclavian vessels. The vein alone was involved in 44 per cent, the artery alone in 39 per cent, and both vessels in 17 per cent. The majority of the victims (61 per cent) did not reach the hospital alive, and in those who were operated on the mortality was 15.5 per cent (overall mortality 66 per cent). The overall mortality of venous injuries was significantly higher than the arterial ones (P less than 0.01), probably because of the dangerous complication of air embolism. Physical examination is reliable in the diagnosis of these injuries and there is no need for an emergency angiogram. The clavicular incision was the preferred approach. Repair was performed in 94 per cent of those with arterial injury. Vein injuries were treated by suture in 60 per cent and ligation in 40 per cent. A selective conservative approach is advised.

Adolescent

Hemodynamic effects of oral isosorbide-5-mononitrate and dinitrate in ischemic heart failure.

Isosorbide-5-mononitrate (ISMN), the main metabolite of isosorbide dinitrate (ISDN) was recently introduced in clinical use. The hemodynamic effects of oral ISMN and ISDN, administered in equal doses, were studied in a randomized, crossover fashion in 20 patients with pump failure of ischemic etiology. Baseline hemodynamic criteria for admission into the study were: pulmonary capillary wedge pressure (PCW) of at least 20 mmHg and systolic arterial pressure (AP) above 90 mmHg. Hemodynamic parameters were serially measured and systemic vascular resistance was calculated up to 6 h postadministration of either ISMN or ISDN single dose (40 mg). Maximal effects obtained were statistically significantly different from baseline. While ISMN and ISDN appeared to be equipotent in reducing the filling pressure, with a maximum effect reached in 60-120 min, the mononitrate maintained its effects for a longer period.

Administration, Oral