Biomedical subjects
Publications and source records attributed to S Nath.
Five patients with advanced upper airway obstruction due to goiter were identified in our institution. All had symptoms of respiratory insufficiency to such a degree that surgery was clearly indicated. Functional characteristics of this group were compared with prior series of goiter patients who had less severe respiratory symptoms. A peak inspiratory flow less than 1.5 L/sec characterized this group who required surgery.
The maturational sequence of growth in the transverse measures of head, face and trunk has been studied on a sample of 500 male Jats of North India, measured cross-sectionally, ranging in age from 10.0 to 19.0 years. This clearly reveals the existence of both cephalo-caudal and caudo-cephalic directions of maturation. The existence of multiple gradients is also observed at different age levels within the head and face measures and also between the cephalo-facial and trunk breadths. Growth has not ceased among Jats of North India by age 19, and a slight increase in the breadths of head, face and trunk is expected beyond 19 years.
Although a delayed visual evoked potential is considered to be the hallmark of optic nerve disease, relatively little has been published about VEP delays in macular disease. In this study, 20 patients with either acquired unilateral maculopathy or bilateral maculopathy in which one eye was more affected than the other were evaluated. VEP amplitudes and peak latencies were compared between eyes when recordable. Nine patients (45%) exhibited significant interocular delays in the affected or more affected eye while only four patients (20%) exhibited significant interocular attenuations in amplitude. In the nine patients exhibiting delays, three patients had a visual acuity of 20/30 or better in the affected eye or more affected eye. In the patients exhibiting amplitude attenuations, no patient had a visual acuity better than 20/50 in the affected or more affected eye. Although the mechanism of VEP delays in maculopathy is not clear, a VEP delay, in isolation of other tests, should not be used in the differential diagnosis of macular vs optic nerve disease. The clinician should specifically rule out macular disease in any patient with a delayed VEP before presuming the presence of a visual pathway dysfunction.
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Halothane was administered at an end-tidal concentration of 1% to 10 patients with stable ischaemic heart disease and clinical and haemodymanic signs of moderate heart failure. Measurements of central haemodynamic variables, coronary sinus blood flow and oxygen, lactate and hypoxanthine balances over the myocardium were done before and at steady state during halothane anaesthesia. Halothane induced marked haemodynamic changes with decreases in mean arterial pressure (-43%), mean pulmonary arteriolar occlusion pressure (-42%), systemic vascular resistance (-31%), cardiac index (-20%) stoke volume index (-31%) and left and right stroke work indices (-62% and -55%, respectively). Heart rate and pulmonary vascular resistance did not change. Coronary sinus blood flow decreased in parallel with perfusion pressure, and myocardial oxygen consumption decreased (-40%), as did myocardial oxygen extraction. Rate pressure product and triple product correlated better with changes in myocardial oxygen consumption in the present subset of patients than in healthy volunteers during halothane anaesthesia. The findings suggest that halothane, through its systemic vasodilatory effect, unloads the failing left ventricle and that this peripheral action predominates over the direct cardiodepressant action of the agent. The combined findings of unchanged coronary vascular resistance, decreased myocardial oxygen extraction and absence of increasing or pathological levels of lactate and hypoxanthine in coronary sinus blood imply a direct dilatory effect of halothane on the coronary vasculature.
Eight patients with stable ischaemic heart disease were investigated to determine the effects of fentanyl (15 micrograms/kg) - droperidol (150 micrograms/kg) - nitrous oxide (75%) anaesthesia, without concomitant fluid challenge, on myocardial oxygen consumption and lactate uptake, and central and coronary haemodynamics. Anaesthesia induced reductions in mean arterial pressure (--35%, P less than 0.01), systemic vascular resistance (--30%, P less than 0.01), left ventricular stroke work index (--50%, P less than 0.01) and total body oxygen consumption (--23%, P less than 0.01), with no changes in heart rate, cardiac output or mean pulmonary arteriolar occlusion pressure. Mixed venous oxygen content increased (P less than 0.05). Systemic vasodilatation, circulatory adaptation to an overall lower metabolic rate, and clinically negligible cardiodepression are the likely mechanisms behind the central haemodynamic response to this form of anaesthesia. Coronary sinus blood flow (measured by the continuous thermodilution technique) decreased (P less than 0.01) in parallel with the decrease in coronary perfusion pressure. Thus coronary vascular resistance remained unchanged. As expected from the haemodynamic findings, myocardial oxygen consumption decreased (--37%, P less than 0.01). Coronary sinus oxygen content and myocardial oxygen extraction did not change, nor was myocardial lactate uptake affected. No ST-T-segment depressions or dysrhythmias were recorded. These observations indicate that myocardial oxygenation was adequate in spite of the reduction in coronary perfusion pressure. There was poor correlation between changes in myocardial oxygen consumption and rate pressure product (R = 0.455) or triple produce (R - 0.375).
A thoracic epidural block from T1 to T12 was performed with plain prilocaine in four patients with coronary artery disease who were scheduled for abdominal aortic aneurysm surgery. The hemodynamic effects of the block consisted of marked reduction in arterial blood pressure due to impairment of cardiac performance and reduction in systemic vascular resistance. The heart rate decreased moderatetly. The epidural block induced a marked reduction in coronary vascular resistance with only a moderate decrease in coronary sinus blood flow. The myocardial oxygen and lactate utilization decreased in parallel to the decrease in cardiac work. In spite of the absence of arrhythmias and ST-T-segment changes following the epidural block, regional myocardial dysoxia could not be ruled out with the present methods. Administration of the cardioselective beta 1-adrenoreceptor agonist prenalterol increased cardiac performance and thereby arterial blood pressure, but did not affect the systemic or coronary vascular resistance.
Break in bud dormancy in virus-infected stem cuttings of Euphorbia pulcherrima occurs because of the higher quantity of gibberellins present in them than in healthy cuttings in the dormant period of the plant.
The hemodynamic effects of prenalterol, a new beta1-adrenoreceptor agonist, on hypotension induced by a thoracic epidural block extending between T1 and T12 and thereby blocking the cardiac sympathetic supply have been studied in eight patients scheduled for abdominal aortic aneurysm resection. The thoracic epidural block induced a drop in blood pressure, due to a reduction in cardiac output and systemic vascular resistance. Intravenous infusion of 10 mg of prenalterol rapidly and effectively reversed the hypotension by an increase in cardiac output without any effects on systemic vascular resistance or heart rate. The results indicate that prenalterol is a pure beta1 agonist with a marked inotropic but no chronotropic property.
Sixteen patients scheduled for abdominal aortic resection and grafting were randomly assigned to two groups to study the cardiovascular effects of infrarenal aortic cross-clamping. The patients in the first group had received a thoracic epidural block followed by intravenous administration of the selective beta-1-adrenoreceptor agonist prenalterol prior to induction of general anaesthesia. The patients in the second group served as controls and received no specific treatment prior to general anaesthesia. In both groups, aortic cross-clamping was followed by an equal rise in pulmonary artery diastolic pressure and mean systemic arterial pressure. There was a significant difference in systemic vascular resistance, as the control group had a 46% increase 30 s after cross-clamping, while the pretreated patients had only a 7% increase at the same time. Moreover, the patients given the thoracic epidural block followed by prenalterol increased their stroke volume and cardiac indices, as compared to the patients in the control group who showed a significant decrease in these parameters. Possible mechanisms for the mode of action of the combined thoracic epidural block and beta-1-adrenoreceptor agonist pretreatment are discussed.
A cyclodialysis spatula for glaucoma surgery with a fiber-optics bundle incorporated within its thickness is described. The instrument is used as is commonly done at present with the standard cyclodialysis spatula. In addition, the fiber-optics bundle delivers cold light to the tip of the spatula which is useful in helping the surgeon locate the spatula within the sclera and the anterior chamber.
The eggs and larvae are affected by the changes in the humidity level around them. The eggs do not develop below 87% relative humidity at 30 degrees C and 25 degrees C. At sub-developmental rel. hum. they remain viable for 30 h at 81%, but at 73% rel. hum. level they do not survive beyond 18 h. Survival of larvae in 100% rel. hum. is longer at 30 degrees C than at 25 degrees C and 35 degrees C, and also they exhibit a poor resistance to desiccation.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.