Search PubMed⌕ Search

Biomedical subjects

S Lakshminarayan

Publications and source records attributed to S Lakshminarayan.

At least 73 records · Page 4Linked to original sources
PubMed1979

Pulmonary injuries associated with acute sulfur dioxide inhalation.

This report describes an industrial accident in which 5 previously healthy persons were acutely exposed to very high concentrations of sulfur dioxide. Of these 5 subjects, the 2 with the highest exposure died immediately; histologic examination of the lungs revealed extensive sloughing of the mucosa of large and small airways along with hemorrhagic alveolar edema. The 3 survivors were evaluated with pulmonary function tests performed at regular intervals. One subject subsequently developed symptomatic severe airway obstruction unresponsive to bronchodilators; another subject developed asymptomatic mild obstructive and restrictive disease, and the third subject continued to be asymptomatic with normal pulmonary function tests. This report severe to document the histologic features of fatal exposure to sulfur dioxide and stresses the need to follow parameters of pulmonary function in the nonfatal cases.

Accidents, Occupational↗
PubMed1979

The significance of wheezing in chronic airflow obstruction.

Eighty-three patients with chronic airflow obstruction were examined prospectively to determine the relationships among wheezing intensity, severity of obstruction, and response to inhaled isoproterenol. For each patient, expiratory wheezing scores were assigned during deep unforced breathing and during forced vital capacity efforts at spirometry. Unforced wheezing scores were independently correlated with severity of obstruction (r = 0.42) and bronchodilator response (r = 0.46), but these correlations did not permit consistent prediction of either variable for clinical purposes. The highest wheezing scores, however, were uniformly associated with moderate or severe obstruction. Twenty-nine of 48 patients with wheezing but only 3 of 35 patients without wheezing demonstrated 15% or greater improvement in one-second forced expiratory volume after bronchodilator inhalation (p less than 0.001). Wheezing during forced exhalation was not correlated with either degree of obstruction or bronchodilator response.

Aged↗
PubMed1979

Increased surface tension favors pulmonary edema formation in anesthetized dogs' lungs.

The possibility that surface tension may affect the hydrostatic transmural pressure of pulmonary vessels and the development of pulmonary edema was studied in anesthetized, open-chested dogs. Isogravimetric pressure (the static intravascular pressure at which transmural osmotic and hydrostatic pressures are balanced such that net fluid flux is zero and lung weight is constant) was measured in nine animals under three conditions: (a) control, normal surface tension, at an alveolar pressure of 30 cm H2O with the apenic lung at room temperature; (b) after increasing surface tension by cooling and ventilating at a low functional residual capacity, at an alveolar pressure sufficient to produce the same lung volume present during control measurements; and (c) after restoring surface tension by rewarming while holding the lung at a high inflation volume, again at the control lung volume. Lung volumes were established from external dimensions and confirmed +/- 10% by deflation spirometry. The isogravimetric pressure (relative to alveolar pressure) was significantly less with increased surface tension than during either the initial control condition (P less than 0.01), or when the surface tension has been restored (P less than 0.01). Similar changes occurred in each of three additional studies performed with control alveolar pressures of 10 cm H2O. Thus, increased surface tension favors fluid leakage presumably because it increases the microvascular transmural pressure.

Anesthesia↗
PubMed1978

Lung injury following a 50-metre fall into water.

The pulmonary complications of a 50-metre fall to the water (a form of suicide attempt producing 87% mortality) were studied in 15 survivors. Presenting findings included crackles, haemoptysis, and hypotension. The alveolar-arterial oxygen difference was greater than 150 mmHg (20 kPa) in nine subjects on admission. Ventilatory failure developed in 10 of the patients, including all of those with massive haemoptysis. Radiographic findings included pneumothorax and diffuse pulmonary opacities adjacent to the area of impact. Pneumothorax developed within 12 hours of admission in 10 of 15 subjects but was associated with rib fractures in only four subjects. The clinical course of the condition is consistent with the hypothesis that the traumatic pulmonary tears produced interstitial emphysema, with subsequent development of pneumomediastinum, subcutaneous emphysema, and pneumothorax. Pneumothorax is a common complication of severe lung contusion even in the absence of penetrating pleural injury.

Adult↗
PubMed1978

Fluid leaks from extra-alveolar vessels in living dog lungs.

Edema transudation from extra-alveolar vessels was investigated in anesthetized, open-chested dogs. Fluid accumulation at different alveolar and extra-alveolar vascular pressures was assessed by continuous lung weighing and microscopy. The left (experimental) lung was distended with 6% CO2 and air while normal arterial blood gases were maintained by separately ventilating the right lung. Extra-alveolar vessels were isolated by compressing alveolar vessels with alveolar pressures high enough to stop blood flow. Weight increased steadily (edemogenesis) when pulmonary arterial and/or pulmonary venous pressure was 1 cmH2O below this pressure. Because some alveolar vessels at the lung base could have remained open and leaked, extra-alveolar vessels were also separated from alveolar vessels by glass bead embolization sufficient to stop perfusion. Lung weight gains followed selective pulmonary arterial or venous pressure elevations. Electron microscopy demonstrated edema in experimental lobes which was not present in control lobes with undistended extra-alveolar vessels at the same alveolar pressure. Thus pulmonary edema can be caused by fluid leaking from extra-alveolar vessels.

Animals↗
PubMed1978

Effect of aminophylline on ventilatory responses in normal man.

The bronchodilator effects of aminophylline have been well documented but its effect on ventilatory drives has not been systematically evaluated. Accordingly, the ventilatory responses to hypoxia and to hypercapnia were measured before and after the intravenous administration of 5 mg of aminophylline per kg of body weight to 6 normal subjects. Hypoxic ventilatory response, as measured by an index of the relation between ventilation and hypoxia (parameter A) increased from a mean +/- SE control value of 146 +/- 25 to 254 +/- 35 75 min after the infusion (P less than 0.05). Significant increases in A were also noticed immediately after and 35 and 50 min after the aminophylline infusion. Oxygen consumption increased from a control value of 235 +/- 21 to 263 +/- 21 ml per min STPD (P less than 0.03), and CO2 production increased from 184 +/- 12 to 202 +/- 13 ml per min STPD (P less than 0.01) after aminophylline. Hypercapnic ventilatory response, measured as the slope of the ventilatory response to hypercapnia, was not altered after the aminophylline. Thus, in addition to bronchodilation, the augmentation of the ventilatory response to hypoxia may be a useful factor when this drug is used in acute respiratory failure secondary to airway obstruction.

Adult↗
PubMed1978

The effect of fiberoptic bronchoscopy on cardiac rhythm.

Cardiac rhythm was monitored in 70 patients prior to, during, and following fiberoptic bronchoscopic procedures. Minor abnormalities in rhythm were frequent. Major cardiac arrhythmias occurred in 11% (8/70) of the patients during the bronchoscopic procedure. All arrhythmias were self-limited and had no hemodynamic consequence. Patients with evidence of coronary arterial disease, chronic obstructive pulmonary disease, or previously known premature ventricular contractions were at no higher risk for developing major arrhythmias. Hypoxemia (arterial oxygen pressure less than 60 mm Hg) at the end of the procedure correlated significantly with the development of new major arrhythmias.

Adult↗
PubMed1976

Effect of diazepam on ventilatory responses.

To investigate the effects of diazepam on ventilatroy control, hypoxic and hypercapnic ventilatory responses were studied in 8 normal subjects before and after 10 mg of intramuscular diazepam. There was no significant change in either resting minute ventilation or resting end-tidal CO2 tension, but depression of hypoxic ventilatory response was observed 15 (60% of control) and 30 min (53% of control) after diazepam (p less than 0.05). No significant depression of hypercapnic ventilatory response was noted 70 to 130 min after diazepam. In view of the depression of hypoxic ventilatory response by diazepam in normal subjects, adverse responses along these lines should be considered in patients with impaired ventilatory function, such as chronic airways obstruction, and in those encountering acute hypoxemia.

Adolescent↗
PubMed1976

Tuberculosis after corticosteroid therapy.

Fourteen episodes of reactivation of tuberculosis after corticosteroid administration are reported. In most a disease impairing the host defences was present and four were taking additional immunosuppressants. The most common presenting symptoms were productive cough and malaise. Bacteriological diagnosis required bronchoscopy in three cases. Response to antituberculosis therapy was good. Five of the 14 episodes manifested dissemination of pulmonary tuberculosis with four occurring in patients receiving high-dose corticosteroids and other immunosuppressants. No prolongation of sputum conversion time was noted in the patients. The published effects of corticosteroids on the tuberculous state are reviewed. Because INH administration may cause liver damage in a small minority of patients, a reassessment is required of the need for INH chemoprophylaxis when corticosteroids are used in patients with healed tuberculosis.

Adrenal Cortex Hormones↗
PubMed1976

Pleural mesotheliomas--an analysis of 18 cases and review of the literature.

Eighteen cases of mesothelioma, 7 benign and 11 malignant, were analyzed retrospectively. There were 5 females with benign tumors and 10 males with the malignant variety. The mean age was 59 years in the benign group and 55 years in those with malignant tumors. Exposure to asbestos was documented in one benign and five malignant mesotheliomas. Three patients with benign lesions were asymptomatic on presentation while all 11 with malignant tumors had symptoms, chest pain and dyspnea being the most frequent. Abnormal physical findings were rarely noted in the benign group while all the malignant tumors had abnormal findings on presentation. Signs of a pleural effusion were the most common abnormal physical findings, occurring in 8 of 11 patients. Pleural effusion was the most common roentgenologic finding in malignant mesotheliomas, while a mass lesion was the presenting finding in six of seven of the benign group. Pleural effusion was a usual accompaniment of malignant tumors and was an exudate, usually hemorrhagic with leukocyte counts up to 20,000/mm3. Thoracotomy established the diagnosis in each of the five benign and seven malignant cases in which it was attempted. Pleural biopsy was diagnostic in three of six with malignant and one of two with benign tumors. Pleural fluid cytology did not yield a diagnosis in the seven instances in which it was studied. Excisional surgery was performed in five of the benign cases and all have survived one to six years. No treatment was curative of malignant mesotheliomas. Ten of the 11 with malignant tumors died from 3 to 24 months after onset of symptoms (mean 9.9 months). The clinical features of 82 benign and 160 malignant mesotheliomas from selected series in the literature are reviewed and compared with the present series. The roentgenographic features of 51 benign and 87 malignant tumors are also presented. The clinical and diagnostic features which help differentiate mesotheliomas from bronchogenic carcinomas are discussed. A careful approach to the diagnosis of malignant mesotheliomas may help avoid an unnecessary thoracotomy.

Adult↗
PubMed1976

Hypertrophic osteoarthropathy in adults with cystic fibrosis.

Three adult patients with cystic fibrosis presented with arthralgia, and investigation for the usual causes of arthritis proved negative. Radiographs of long bones revealed periostitis and new bone fromation characteristic of hypertrophic osteoarthropathy. Symptomatic improvement occurred after analgesic and anti-inflammatory therapy. In patients with cystic fibrosis and bone or joint pain, the diagnosis of hypertrophic osteoarthropathy should be considered and long bone radiographs obtained.

Adult↗
PubMed1976

Prognosis after recovery from adult respiratory distress syndrome.

Ten patients who survived an acute episode of the adult respiratory distress syndrome were studied on recovery. Serial pulmonary function tests performed in 3 subjects revealed a tendency toward normalization of values at 4 to 6 months after the episode, with a subsequent serial decrease in maximal mid-expiratory flow rates, and a partial reversal by bronchodilators. Of the 10 patients, 6 had dyspnea on exertion and all but one of the 6 were smokers. The ventilatory tests revealed a predominantly restrictive pattern in 2 patients and an obstructive pattern in 4. The 4 asymptomatic patients had essentially normal pulmonary function. Pathologic features of the lung, available in 3 cases, are discussed.

Adolescent↗
PubMed1976

Pulmonary effects of chronic exposure to airborne cadmium.

Workers chronically exposed to high concentrations of airborne cadmium showed a significantly decreased forced vital capacity relative to a low-exposure group and had Po2 values in the normal range, but at the extreme low end. They had no significant decrease in 1-sec forced expiratory volume or maximal mid-expiratory flow. Chest roentgenograms showed mild or moderate interstitial fibrosis in 29 per cent of the group exposed to cadmium. Collectively, these results suggest a mild fibrotic reaction associated with exposure to cadmium. A dose-response association was observed between forced vital capacity, expressed as per cent predicted, and both average urinary cadmium concentration (P less than 0.003; r=-0.53) and maximal urinary cadmium concentration (P less than 0.005; r=-0.51). Further, a dose-response relationship was found between the forced vital capacity and months of work in cadmium fume areas, but not for months of exposure to cadmium sulfate aerosol.

Air Pollutants↗
PubMed1976

Unsuspected pulmonary alveolar proteinosis complicating acute myelogenous leukemia.

A patient with acute myelogenous leukemia developed pulmonary alveolar proteinosis in the terminal phase of the leukemia. The diagnosis of pulmonary alveolar proteinosis was unsuspected during life and was established only at autopsy. Other reported cases of the same association are reviewed. This report serves to stress the importance of considering the diagnosis of pulmonary alveolar proteinosis in malignant hematologic diseases and the need for hematologic evaluations in pulmonary alveolar proteinosis.

Autopsy↗