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Biomedical subjects

S S Lefrak

Publications and source records attributed to S S Lefrak.

34 records · Page 2Linked to original sources
PubMed1987

Determination of resting energy expenditure utilizing the thermodilution pulmonary artery catheter.

Accurate determination of the resting energy expenditure (REE) for patients in intensive care units has assumed increasing importance as the adverse effects of underfeeding or overfeeding have become clearer. As a result, indirect calorimetry is frequently used to determine the REE. This technique, however, is neither universally available nor inexpensive. Furthermore, it requires meticulous measurements of gas exchange and technical expertise. Because of this, we have developed a method to determine REE for those patients in intensive care units who have thermodilution pulmonary artery catheters in place. This method requires determining the oxygen consumption from data obtained from such a catheter. The REE is then calculated by multiplying the determined oxygen consumption by the caloric value for oxygen (4.86 kcal/L at a nonprotein respiratory quotient of 0.85). We made 20 simultaneous measurements of REE, comparing our method with indirect calorimetry in 19 patients. There was excellent agreement between both methods (r = 0.90; p less than 0.0001). Therefore, for those patients in intensive care units who require thermodilution pulmonary artery catheters, this method will allow accurate determination of REE and thus caloric requirements, without the need for indirect calorimetry using measurements of gas exchange.

Calorimetry, Indirect↗
PubMed1981

Posterior packs and the nasopulmonary reflex.

Increased mortality and arterial hypoxemia have long been associated with posterior nasal packs placed for control of severe epistaxis. Several authors have postulated a nasopulmonary reflex to partially explain this clinically observed phenomenon. In ten young, healthy subjects, using a multiparameter pulmonary evaluation, posterior nasal packs were placed and no significant changes were observed in lung volumes, flow and alveolar gas exchange, especially oxygenation. These findings suggest that aspiration, sedation, and degeneration of pulmonary function with age, not a nasopulmonary reflex, have not been adequately emphasized in previously performed studies.

Adult↗
PubMed1980

Prolonged mechanically assisted ventilation. An analysis of outcome and charges.

Mechanically assisted ventilation is frequently used, but there are little data regarding cost and long-term outcome. Therefore, all patients who required mechanical ventilation for 48 hours or more were studied, their hospitalization charges analyzed, and the survivors observed for two years after discharge. The mean charge for the hospitalization was $12,300, compared with $1,600 for all other hospitalized patients. Although the overall mortality at discharge was 56%, the patients with pulmonary disease had the lowest mortality (29%) with the lowest cost at time of discharge. The mortality for the postoperative and miscellaneous medical group of patients demonstrated no significant increase during the period following discharge, unlike the cardiac and pulmonary groups, whose mortality increased each year of follow-up. Hospitalization for these patients was eight times as costly as for all other hospitalized patients during the same 12 months, with a two-year mortality of 72%.

Aged↗
PubMed1978

Alveolar-capillary oxygen disequilibrium in hepatic cirrhosis.

Hypoxemia is a frequent occurrence in patients with severe hepatic disease. Multiple mechanisms have been implicated in the production of such hypoxemia. The case of a 35-year-old man with cyanosis, clubbing, and cirrhosis is presented. Physiologic data from this patient revealed normal pulmonary function, except for a low diffusing capacity and a 28 percent shunt while the patient was breathing 100 percent oxygen. A perfusion scan with radioactive 99mtechnetium-labelled macroaggregated albumin revealed 67 percent of the labelled macroaggregated albumin in the systemic circulation. Post-mortem examination demonstrated normal pulmonary parenchyma, markedly dilated intraparenchymal capillaries and arterioles, subpleural angiomata, and cirrhosis. No anatomic arteriovenous connections were demonstrated before or after death. We conclude that the arterial hypoxemia of some patients with hepatic cirrhosis results from dilated gas-exchanging blood vessels. These widened vessels prevent end pulmonary capillary oxygen tension from reaching equilibrium with alveolar gas, perhaps because of the widened distance for diffusion.

Adult↗
PubMed1978

How aging affects the structure and function of the respiratory system.

Age-associated changes in the lung resemble emphysema. Progressive loss of the aging lung's static recoil forces produces airway closure at lung volumes in the tidal volume range,which leads to decreased arterial Po2. Under conditions that decrease oxygen content of arterial blood, the increase in both ventilation and cardiac output is smaller in elderly persons than in younger subjects. Therefore, less oxygen may be delivered to the tissues. Muscular strength of the respiratory apparatus consistently declines and the chest wall stiffens with advancing age. Thus, the elderly have weaker muscles to act on a chest wall that becomes progressively harder to move. Both maximal inspiratory and expiratory pressures are significantly decreased. Loss of the functional reserve of the respiratory system with age increases the risk of respiratory failure and leaves elderly subjects with decreased compensatory mechanisms for dealing with even moderate stress. The physician must be aware of these problems and provide early and vigorous respiratory care for elderly patients.

Adult↗
PubMed1976

Unilateral lung function. Comparison of the lateral position test with radionuclide ventilation-perfusion studies.

Twenty-seven patients underwent studies of unilateral lung function by the lateral-position test (LPT) and by computer-analyzed radionuclide imaging of ventilation and perfusion. The patients were divided into two groups, symmetric or asymmetric, on the basis of the physical examination of the chest and the chest radiograph. In patients with symmetry, the estimate of unilateral lung function by the LPT and isotopic estimates for unilateral lung volume, unilateral distribution of tidal volume, and unilateral perfusion, agreed within 2 percent, 4 percent, and 3 percent, respectively. In patients with asymmetry, the differences were 9 percent, 8 percent, and 13 percent. In settings of marked unilateral ventilation-perfusion imbalance, the LPT primarily reflected ventilation. Prediction of unilateral ventilatory function based upon the LPT and spirometric measurements agreed closely with unilateral ventilation determined isotopically by 133xenon, even in the presence of chronic obstructive lung disease. Our results confirm that the LPT provides valid information about unilateral lung function.

Adult↗
PubMed1976

How to detect and treat arrhythmias in chronic lung disease.

Investigators suspect that arrhythmias are behind the high incidence of sudden death in patients with severe chronic bronchitis and emphysema. Continuous electrocardiographic monitoring may help boost survival statistics, since it has repeatedly shown its ability to detect irregularities that standard ECGs miss. So-called benign arrhythmias, such as atrial fibrillation, frequent ventricular premature contractions, and atrial flutter, are anything but harmless. In patients whose heart and lung function is already impaired by severe airway obstruction, these rhythm disorders can rapidly progress to a fatal cardiac arrest. Deciding how to treat the arrhythmia depends on the type of disturbance and the patient's clinical status. Direct-current shock or antiarrhythmic drugs can turn the tide in a desperately ill patient with acute respiratory failure. Correction of coexisting metabolic and ventilatory disorders often is crucial to successful therapy.

Aged↗
PubMed1976

The left ventricle in emphysema and chronic bronchitis.

There's no doubt that chronic obstructive lung disease can have a disastrous impact on the heart's right ventricle--often producing hypertrophy or even failure--but its effects on the left ventricle are less clear. Some researchers speculate that disease of the right ventricle leads to disease of the left, while others consider the lung disease itself to be the more likely mechanism. Ordinarily, the left ventricle holds up well, even in far-advanced emphysema and chronic bronchitis. Recognizing the cases that do occur is important, however, since only minimal left ventricular failure can seriously compromise respiratory function. Treatment is the same as for left ventricular failure of any cause, but special precautions should be observed, particularly in prescribing diuretics. If frank pulmonary edema supervenes, mechanical ventilation and supplemental oxygen are necessary.

Aged↗
PubMed1975

Status asthmaticus.

Explore the source record for details and available documents.

Administration, Oral↗
PubMed1975

The Jewish Hospital of St. Louis therapeutic grand rounds number 10. Chemoprophylaxis of tuberculosis.

Isoniazid therapy has been proved an effective means of preventing overt clinical tuberculosis in persons with positive tuberculin skin tests, persons who are close contacts of active cases, and persons with inactive tuberculosis that were never treated. The administration of isoniazid in standard dosage for one year in these situations will help greatly to reduce tuberculosis as a community health problem in the future. Studies in recent years, however, point to hepatic dysfunction as a complication of isoniazid therapy in up to 10% of patients. In a few patients, liver disease as a complication of this therapy has been fatal. The likelihood of this complication increases with age. Accordingly, isoniazid chemoprophylaxis should be undertaken with the understanding that the patient has to be followed up closely, especially for evidence of liver disease during the course of therapy. This potentially serious side effect suggests that isoniazid chemoprophylaxis should be used primarily with patients in high risk groups.

Adult↗
PubMedDate not supplied

Disturbances of rhythm in chronic lung disease.

Patients with chronic obstructive lung disease have a high incidence and wide variety of cardiac arrhythmias. These arrhythmias are often clinically significant and may be life threatening. Although they occur particularly in the context of acute respiratory failure, arrhythmias are not infrequent in clinically stable patients. The relatively high incidence of sudden arrhythmias seen in acute respiratory failure are associated with a very poor prognosis, in particular, ventricular premature beats and multifocal atrial tachycardia. Long-term electrocardiographic monitoring is valuable in increasing the detection of these arrhythmias and in assessing their clinical significance and response to therapy. The mechanisms producing these arrhythmias are poorly understood and probably multiple. However, disturbances of blood gases, blood pH, and electrolytes or the presence of cor pulmonale or associated coronary artery disease is probably important. The therapy of these arrhythmias must include efforts to improve the patient's ventilatory status as well as careful use of standard antiarrhythmic drugs. Further investigation is needed to define the mechanisms, determine the prognosis, and improve the therapy of the arrhythmias found in chronic obstructive lung disease.

Arrhythmias, Cardiac↗