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Biomedical subjects

M D Klein

Publications and source records attributed to M D Klein.

At least 55 records · Page 3Linked to original sources
PubMed1989

Monotherapy of stable angina with nicardipine hydrochloride: double-blind, placebo-controlled, randomized study.

The effect of nicardipine hydrochloride, a calcium-channel blocking agent, was studied in 46 patients with stable angina in a double-blind, placebo-controlled, randomized, repeated cross-over protocol, using a 30 or 40 mg dose of nicardipine or placebo three times a day. Mean resting heart rate and blood pressure did not change significantly with 30 mg nicardipine; heart rate increased from 81 +/- 10 to 88 +/- 13 beats min-1, systolic blood pressure decreased from 129 +/- 18 to 119 +/- 16 mmHg, and diastolic blood pressure from 81 +/- 12 to 74 +/- 11 mmHg (P less than 0.01 for all three variables) with a 40 mg dose. Using a treadmill exercise protocol, mean exercise duration increased from 5.4 +/- 1.8 to 6.0 +/- 1.8 min (P less than 0.01) with 30 mg nicardipine, and from 5.8 +/- 1.7 to 6.6 +/- 1.9 min (P less than 0.01) with 40 mg. Time to onset of angina increased from 4.6 +/- 1.9 to 5.2 +/- 1.7 min (P less than 0.05) with 30 mg and from 5.1 +/- 1.8 to 5.7 +/- 1.8 min (P = NS) with 40 mg. Mean anginal frequency and sublingual nitroglycerin consumption were low during the cross-over placebo period and did not change significantly during therapy with nicardipine. Non-cardiac side-effects were mild and required the withdrawal of only one patient from the study. However, during nicardipine therapy four patients had unstable angina and two developed a non-Q wave myocardial infarction. Of these patients, five were receiving a beta-adrenergic blocker that was discontinued prior to the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Streptococcal pharyngitis in children.

Children with suspected group A beta-hemolytic streptococcal pharyngitis are encountered daily in outpatient settings. Despite the ubiquity of this condition, important management issues still remain unresolved. This article will review selected epidemiologic, diagnostic, and therapeutic topics germane to clinical practice.

Agglutination Tests↗
PubMed1989

Simultaneous pneumococcal arthritis and osteoarticular tuberculosis.

We have reported the case of a 79-year-old woman who had a pneumococcal pyarthrosis in a chronically swollen knee. Expected improvement did not occur despite appropriate medical and surgical therapy. Mycobacterium tuberculosis was subsequently cultured from fluid aspirated from the patient's joint. This is the first reported case of concomitant pneumococcal pyarthrosis and osteoarticular tuberculosis.

Aged↗
PubMed1989

Regional blood flow distribution during extracorporeal membrane oxygenation in rabbits.

To study regional blood distribution during extracorporeal membrane oxygenation, we stabilized three groups of five rabbits each (3 to 5 kg) on venoarterial bypass at a flow rate of 30 ml/kg/min. Albumin aggregates (15 to 30 microns) labeled with technetium 99m were injected into the left ventricle during bypass (ventricle), the perfusion cannula during bypass (cannula), and the left ventricle with no bypass (control). Animals were put to death, organs were removed, and the percent distribution was determined with a gamma camera. The Student Newman-Keuls test was used for statistical comparisons. Distribution to both the heart and brain in the cannula group were decreased from control by 55% and 35%, respectively. Distribution to the brain in the ventricle group was also decreased from control by 39%. Intestinal distribution was elevated above control in the ventricle group by 37%, whereas musculoskeletal distribution was elevated 33% above control in the cannula group. No significant changes were noted for the kidneys, stomach, or liver. These data suggest that overall perfusion of some vital organs may be significantly reduced during low-flow extracorporeal membrane oxygenation, specifically in the case of the heart and brain, which may be deprived of oxygenated blood.

Animals↗
PubMed1989

Extracorporeal membrane oxygenation without anticoagulation: a study using quantitative scanning electron microscopy.

In current clinical applications of extracorporeal circulation (ECC) of blood, heparin is administered to prevent thrombosis in the circuit and to eliminate thromboembolism in the patient. Systemic heparinization, however, causes impairment of normal coagulation properties and significantly increases the risks of major bleeding complications. It has been observed in the past that ECC may be performed in the absence of any systemic anticoagulants or material surface treatments. In this study, short-term extracorporeal membrane oxygenation (ECMO) was performed on rabbits in three groups. The animals in the first group received standard clinical dosages of heparin. No form of anticoagulation was used in the second group. The ECMO circuits in the third group were treated with an albumin-heparin complex surface-coating. Thrombosis in the extracorporeal circuit was evaluated by using quantitative scanning electron microscopy. The results indicated very few statistically significant differences between the three experimental systems in the amounts of blood components adhering to the surface. Considerably more platelet activation and attachment was noted in the systemic heparin group. These experiments failed to demonstrate any benefit of systemic heparinization in short-term ECMO. The findings from these experiments suggest that the current levels of systemic heparinization may be unwarranted, and they indicate that more controlled studies must be performed to determine optimal levels of anticoagulation for different applications of ECC.

Animals↗
PubMed1989

Postoperative bleeding in cardiovascular surgery. Does heparin rebound really exist?

Postoperative bleeding following cardiovascular procedures is troublesome and often life-threatening. The effect of heparin (H) is usually reversed with protamine sulfate (P) at the end of vascular procedures; subsequent bleeding or abnormal coagulation times are ascribed to so-called heparin rebound and are treated with extra empiric doses of P. H rebound has heretofore been described only by using biologic clotting tests, which are often abnormal postoperatively. Thus, many instances of postoperative bleeding are treated with inappropriate and dangerous doses of P in the mistaken impression that more H needs to be reversed. Using the new test for plasma H, the azure A Assay, which measures H chemically rather than biologically, 27 patients were tested after cardiac bypass surgery to determine whether H rebound truly exists. Azure A levels of H were measured before the bypass procedure and every half hour from 0-8 hours after bypass in routine coronary artery bypass patients. Tests for prothrombin time (PT) and partial thromboplastin time (PTT) were performed simultaneously. The azure A test was performed on 252 samples of blood in the 27 patients; only one sample drawn anytime except immediately after bypass contained measurable H (0.4%). This sample became negative for H in the ensuing 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Azure Stains↗
PubMed1988

The role of exercise testing in evaluation of arrhythmias.

Exercise testing has been widely applied for the evaluation of patients with coronary artery disease. The principles underlying its use for this indication make it a useful adjunctive technique, when combined with ambulatory monitoring, to diagnose arrhythmias and monitor antiarrhythmic drug therapy. During exercise, there is a withdrawal of vagal tone and a marked increase in circulating catecholamines and sympathetic inputs to the heart. These changes may directly cause arrhythmias (e.g., catecholamines can enhance automaticity and delayed afterpotentials and can shorten myocardial conduction time and refractory periods). However, they also augment myocardial oxygen demands by increasing myocardial inotropy, heart rate and blood pressure. Such changes may cause ischemia in patients with heart disease, which is a powerful stimulus for arrhythmia, or lead to dysfunction in left ventricular contraction and increased myocardial wall stress, factors that also may precipitate arrhythmia. In approximately 10% of patients with a history of serious arrhythmia, exercise represents the only means for exposing arrhythmia. Importantly, this technique is useful for evaluating the effect of antiarrhythmic drugs. These agents work by reducing membrane automaticity, slowing impulse conduction through the myocardium and prolonging membrane refractoriness. In contrast, catecholamines, which are secreted in response to exercise, have the opposite effect. Thus, exercise may negate the important effects of the antiarrhythmic drugs. Additionally, exercise testing may expose potentially serious toxic drug reactions that may not be obvious at rest. These include conduction abnormalities, negative inotropic effects, congestive heart failure and aggravation of arrhythmia. Although the presence and frequency of arrhythmia with exercise is highly variable in patients with benign arrhythmia, results are more consistent in patients with a history of serious arrhythmia. If arrhythmia is reproducibly provoked with exercise, this technique can be used to judge drug effect. Thus, exercise testing is an important, reliable and helpful technique for exposing arrhythmia, evaluating drug efficacy and identifying potentially serious toxic drug effects.

Anti-Arrhythmia Agents↗
PubMed1988

Ultrasonographic findings (CNS, thorax, abdomen) in infants undergoing extracorporeal oxygenation therapy.

Extracorporeal membrane oxygenation (ECMO) has been performed on 45 neonates at the Children's Hospital of Michigan in a 39-month period. Ultrasound evaluation of these patients prior to and during ECMO therapy has demonstrated abnormalities in the central nervous system including intracranial hemorrhage (21), extra-axial fluid collections (5), and ventricular enlargement (2). Ultrasonic evaluation of the thoracic cavity in 12 infants revealed pleural fluid in 8. There were seven children with varying types of peritoneal fluid. Two children had visceral abnormalities - 1 with liver hemorrhage and 1 with hydronephrosis found prior to ECMO. Most of these findings could not have been diagnosed without ultrasound and may lead directly to alterations in clinical management. Ultrasound is an extension of physical examination which is important in hour-by-hour clinical care of patients on ECMO.

Ascitic Fluid↗
PubMed1988

Pancreatitis in childhood. Experience with 49 patients.

Pancreatitis in children is not common but can be associated with severe morbidity rates. We have treated 49 children with pancreatitis over the past 12 years ranging in age from 1 month to 18 years. One third of the patients had biliary tract disease as an etiology, with nearly half of these being related to underlying hematologic disease, usually sickle cell anemia. Another third of the pancreatitis was due to trauma, and one third of these were related to child abuse. Other etiologies were systemic disease (6 patients), congenital anomalies (8 patients), and idiopathic (3 cases). Eighty-two per cent of the patients presented with abdominal pain, but four children, all less than 4 years old, presented with an abdominal mass. Twenty-nine patients required 33 operations for pancreatitis. Fifteen of the 16 patients with biliary tract disease and all patients with congenital anomalies required operation. Six of the 16 patients with trauma required operation and none of those with systemic disease. As in adults ultrasonographic examination and CT scan are most important in the diagnosis; medical treatment consists of intravenous (I.V.) fluids, nasogastric suction, and total parenteral nutrition (TPN), and risk factors can help predict the severity of the disease while amylase alone is not related to severity. Different from adults, in children an etiology can usually be determined. The common etiologies, biliary tract disease, trauma, and congenital anomalies frequently require operation.

Adolescent↗
PubMed1988

Therapeutic and diagnostic benefits of intentional crosstalk mediated ventricular output inhibition.

Ventricular output inhibition due to crosstalk is generally considered unsafe and something that should be avoided. Special circuits have been incorporated in some dual chamber pacing systems to absolutely prevent this from happening. However, in patients with intact atrioventricular conduction, crosstalk mediated ventricular output inhibition can be beneficial to the evaluation and management of the patient. Utilizing this technique, one can achieve single chamber atrial paced rates which greatly exceed the rates allowed by lower rate limit programming to facilitate an assessment of the integrity of AV nodal conduction and to both convert and suppress some pathological tachyarrhythmias. The methods of achieving crosstalk and its utilization in four patients is discussed in this report.

Atrioventricular Node↗
PubMed1988

Ocular findings in infants treated with extracorporeal membrane oxygenator support.

Eleven infants treated with extracorporeal membrane oxygenator support were examined for ocular complications. Four patients were noted to have retinal and external ocular vascular changes on the left but not on the right. These unilateral findings are believed to be related to right common carotid and internal jugular occlusion. The proposed mechanism involves three factors: cerebral venous congestion, impairment of cerebral and possibly retinal arterial autoregulation, and higher cerebral arterial blood flow on the left compared with the right.

Extracorporeal Membrane Oxygenation↗
PubMed1987

Efficacy of sustained-release verapamil in chronic stable angina pectoris.

The effectiveness of a sustained-release preparation of verapamil (verapamil-SR) was compared with the regular formulation of verapamil and with placebo in 12 patients with chronic stable angina pectoris. All patients completed an 8-week, double-blind, double-crossover, randomized protocol with 2-week treatment periods of verapamil-SR, 240 mg twice daily; regular-formulation verapamil, 120 mg 4 times daily; and 2 placebo therapies. The frequency of weekly anginal episodes was reduced from 7.6 +/- 10.0 with placebo to 3.1 +/- 4.2 after the regular formulation of verapamil (p = 0.09) and from 6.4 +/- 7.6 with placebo to 2.8 +/- 4.8 after verapamil-SR (p = 0.06). Treadmill time increased from 384 +/- 144 seconds during the first placebo phase to 468 +/- 138 seconds after the regular formulation of verapamil (p less than 0.01) and from 354 +/- 102 seconds during the second placebo phase to 462 +/- 138 seconds after verapamil-SR (p less than 0.01). Time to the onset of angina was similarly prolonged by formulations of verapamil. There were no significant adverse effects after 1 year in any patient taking verapamil-SR, 240 mg twice daily. Thus, a twice-a-day verapamil-SR dose regimen is safe and is as effective for treatment of angina of effort as the regular formulation given 4 times a day.

Angina Pectoris↗
PubMed1987

Experience with renal failure during extracorporeal membrane oxygenation: treatment with continuous hemofiltration.

We use extracorporeal membrane oxygenation (ECMO) to treat respiratory and cardiac failure in children who are unresponsive to standard ventilator and pharmacologic management. All patients have cardiac and abdominal ultrasonography prior to ECMO to identify major structural anomalies and anatomically normal kidneys. Despite this, oliguric renal failure is seen in a number of patients. Acute renal failure (ARF) developed in two of the first 20 patients we placed on ECMO and both of these patients died. Six of the last 27 patients (22%) also developed ARF and were treated with continuous hemofiltration (CH) placed in-line with the extracorporeal circuit. The technique of CH removes plasma water and dissolved solutes while retaining proteins and cellular components of the intravascular space. The duration of CH ranged from 9 to 112 hours (mean 57.5 hours). Indications for CH were hypervolemia, hyperkalemia, and azotemia. The mean serum potassium prior to CH was 5.6 (range 4.3 to 7.0) compared with 4.5 after filtration. We filtered 5 to 10 mL/kg/h and replaced it with crystalloid chosen on the basis of serum and filtrate electrolytes. These six patients had a 33% mean weight gain prior to CH. We were able to remove as much as 2,200 g in the most edematous patient with significant improvement in cardiopulmonary status. Four of the patients on CH died of their primary pulmonary or cardiac disease without specific problems related to ARF. The other two patients were successfully weaned from ECMO, extubated, and have not needed further therapy for renal failure. We conclude that CH is useful in managing the complications of oliguric renal failure during ECMO.

Acute Kidney Injury↗
PubMed1987

Spontaneous resolution of acid gastric injury.

While alkali ingestion nearly always injures the esophagus, acid usually spares the esophagus and damages the gastric outlet. Most reported cases of acid gastric injury have required resection. We report a case of acid ingestion managed with parenteral nutrition and histamine blockers in which healing is documented without operation.

Acids↗
PubMed1987

Noncardiogenic pulmonary edema following hydrochlorothiazide ingestion.

A 57-year-old woman presented in severe respiratory distress 30 minutes after ingesting hydrochlorothiazide. Pulmonary edema was evident clinically and radiographically. A noncardiogenic etiology was suggested by the lack of jugular venous distention, S3 gallop, or pedal edema, and the presence of a normal cardiac silhouette on chest radiograph. The patient's pulmonary edema remitted with supportive therapy.

Acute Disease↗
PubMed1987

Hypertension during extracorporeal membrane oxygenation: cause, effect, and management.

The major complication of extracorporeal membrane oxygenation (ECMO) for the treatment of neonatal respiratory failure is bleeding related to heparinization. Systolic hypertension has emerged as another serious side effect in our experience. Thirty-eight of the first 41 newborns we treated with ECMO developed a systolic blood pressure greater than 90 mm Hg. The mean hypertension index (HI blood = hours greater than 90/hr on ECMO) was 0.17 +/- 0.16. Possible biochemical mediators were assayed in 17 patients. Plasma renin activity (PRA), aldosterone, epinephrine, norepinephrine, prostaglandin E2, thromboxane, and antidiuretic hormone were elevated. Angiotensin-converting enzyme (ACE) and prostacyclin were not elevated. Eighteen patients (44%) had intracranial hemorrhage (ICH), and 11 patients (27%) had clinically significant ICH. The HI was significantly (p less than 0.005) lower in those patients without ICH (0.11 +/- 0.01) than in those patients with ICH (0.25 +/- 0.04). PRA at hour 12, day 2, and day 3 was significantly higher (p less than 0.05) in patients experiencing ICH (62 +/- 42; 93 +/- 15; 73 +/- 30 ng/ml/hr) than in those without ICH (27 +/- 25; 14 +/- 8; 12 +/- 4 ng/ml/hr). An aggressive approach to medical management evolved that included hydralazine, nitroglycerine, and captopril, which protected against ICH. Two of 23 patients (9%) treated with the protocol sufferred clinically significant ICH, whereas nine of 18 patients (50%) treated before implementation of the protocol experienced ICH. The ACE inhibitor captopril was most effective in the control of hypertension. We conclude that systolic hypertension is common during neonatal ECMO, is associated with ICH, and is related to a high PRA. Aggressive management of hypertension during ECMO can reduce the incidence of ICH, and captopril is an important component of this aggressive medical management.

Aldosterone↗
PubMed1987

Neurogenic pulmonary edema.

Neurogenic pulmonary edema may be a consequence of a number of diverse central nervous system insults, including resection of an acoustic neuroma. Brainstem lesions in particular seem to cause neurogenic pulmonary edema. Diagnosis requires a high index of suspicion, especially in the case of respiratory decompensation following a seizure.

Cerebellar Neoplasms↗