Search PubMed⌕ Search

Biomedical subjects

M Ramanathan

Publications and source records attributed to M Ramanathan.

106 records · Page 6Linked to original sources
PubMed1985

Changing knives a wasteful and unnecessary ritual.

The use of two knives for making a surgical incision is a deeply ingrained practice of British surgery and a postal survey of the theatre superintendents in the South-West Thames Region revealed that out of 143 surgeons all but one use this technique. Therefore we undertook a bacteriological study of the knife blades used on a general surgical unit. This showed that under normal conditions pathogenic organisms do not contaminate the knife blade and are not carried into the wound by it. The use of only one knife to make an incision does not increase the incidence of wound infection. A survey of the world literature confirms these findings. The wasteful and unnecessary ritual of using two knives to make an incision through normal skin has no theoretical, scientific or clinical basis and can be discontinued.

Bacteria↗
PubMed1984

Dimensional analysis of the left ventricle during PEEP: relative septal and lateral wall displacements.

We studied the effects of ventilation with positive end-expiratory pressure (PEEP) on left ventricular (LV) shape and wall motion with emphasis on the relative positions of the septum and lateral LV wall. In seven dogs we implanted radiopaque markers in the LV wall and septum to represent the major and two minor axes of a nonprolate LV ellipsoid and measured their spatial positions using 90 degrees biplane cineradiography. The relative positions of the septum and lateral LV wall were determined with respect to the central longitudinal axis of the heart defined by the apex and base markers. Animals were studied in the supine position during positive-pressure ventilation without PEEP, during PEEP before and after dextran administration to elevate stroke volume, and again without PEEP while blood was withdrawn to lower stroke volume. We found that ventilation with PEEP reduced all three LV chamber end-diastolic dimensions and distorted its shape primarily by restricting the outward expansion of the lateral LV wall during diastole, a change that persisted after stroke volume had been restored. The relative position of the septum was not displaced into the LV by PEEP to any greater degree than were the anterior or posterior walls. The inordinate reduction of the end-diastolic septal to lateral wall dimension, and specifically the lateral wall component thereof, was associated with a proportional reduction in the respective stroke lengths. We conclude that deformation of the LV is more likely caused by lung compression than by right ventricular dilation. This deformation contributes to the reduction in LV filling and thereby contributes to the reduction in stroke volume.

Animals↗
PubMed1980

Hysteresis in the relation between diffusing capacity of the lung and lung volume.

The diffusing capacity of the lung for carbon monoxide (DLCO) varies directly with lung volume (VA) when measured during a breath-holding interval. DLCO measured during a slow exhalation from total lung capacity (TLC) to functional residual capacity (FRC) does not vary as VA changes. Since VA is reached by inhaling during breath holding and by exhaling during the slow exhalation maneuver, we hypothesized that the variability in the relation between DLCO and VA was due to hysteresis. To test this hypothesis, breath-holding measurements of DLCO were made at three lung volumes, both when VA was reached by inhaling from residual volume (RV) and when Va was reached by exhaling from TLC. At 72% TLC, DLCO was 22% higher when VA was reached by exhalation compared to inhalation (P < 0.02). At 52% TLC, DLCO was 19% higher when VA was reached by exhalation compared to exhalation (P < 0.005). DCLO measured during a slow exhalation fell on the exhalation limb of the CLCO/VA curve. these data indicate that there is hysteresis in DLCO with respect to lung volume.

Adult↗
PubMed1980

Servo-controlled lumbar infusions in children. A quantitative approach to the problem of arrested hydrocephalus.

Servo-controlled variable-rate lumbar infusions were performed in 11 children with presumed cerebrospinal fluid (CSF) absorptive defects. The CSF dynamics were determined as a function of intracranial pressure in terms of CSF absorptive capacity and resting pressure. These physiological measurements showed poor correlation with traditional clinical signs. On the basis of the CSF measurements there were four children with arrested hydrocephalus, one with compensated hydrocephalus, three with active hydrocephalus, and three with brain atrophy. Retrospective management decisions based on the clinical presentations, physical findings, and traditional diagnostic tests disagreed with management as indicated by the CSF measurements in eight of 11 cases. It is suggested that this technique may be a useful diagnostic tool for difficult clinical problems.

Atrophy↗
PubMed1979

Cerebrospinal fluid dynamics in patients with pseudotumor cerebri.

CSF dynamics were determined as a function of intracranial pressure in patients with pseudotumor cerebri. Servocontrolled variable rate lumbar infusions were used to determine net CSF-absorptive capacities and resting pressures in 10 patients; serial studies were done in 5 of the patients. Nearly all of the patients had abnormally low CSF-absorptive capacities. On the other hand, marked elevations in resting pressure were not a constant feature of the disease. Concurrent changes in the cerebrovascular bed could introduce errors into this manometric determination of CSF dynamics; the significance of this potential artifact is examined. The results of this study suggest that the CSF compartment may be of etiological importance in the pathophysiology of pseudotumor cerebri.

Adolescent↗
PubMed1977

Dynamic measurement of regional ventilation and perfusion of the lung with Xe-133.

A method for measuring regional distribution of ventilation and perfusion with Xe-133 during tidal breathing was developed with normal subjects, and compared with current breath-holding techniques in patients and in animals. Normal values for a ventilation index during washin, a perfusion index, and a washout slope index were determined in both supine and upright normal subjects. Comparisons of tidal-breathing and breath-holding measurements in patients with localized bullous disease of the lung showed roughly equal values for perfusion index by the two methods, but the tidal-breathing method was more sensitive to abnormalities in ventilation index. During occlusion of branches of the pulmonary artery in animals, the tidal-breathing and breath-holding methods were again comparable in the measurement of perfusion indices, but the tidal-breathing method provided a more sensitive assessment of ventilatory changes due to partial bronchial occlusion in animals. This technique appears superior to standard methods and is well suited to dynamic measurement of regional ventilation and perfusion in a number of experimental and clinical circumstances.

Animals↗
PubMedDate not supplied

Induced abortion potential among Indian women.

Information on abortion is limited and inaccurate, especially in the developing world, which has led to speculation on the prevalence of abortion in these regions. A rise in prevalence of abortion is mostly counted in terms of increase in the prevalence of induced abortions which reflects on the reproductive health of women. With the growing concern for the reproductive health of women, the study of abortion has drawn the attention of researchers world-wide. This paper is an attempt to assess the induced abortion potential among Indian women by utilizing information on proportion of unwanted and ill-timed pregnancies obtained through National Family Health Survey, India. This exercise may facilitate a better understanding of the exact prevalence of induced abortion, which necessarily should be less than the estimated potential depending on the levels of unwanted and ill-timed fertility.

Abortion, Induced↗
PubMedDate not supplied

Servo-controlled lumbar infusions: a clinical tool for the determination of CSF dynamics as a function of pressure.

The variable rate lumbar subarachnoid infusion technique allows rapid quantitative study of the cerebrospinal fluid (CSF) compartment. Numerous pressure plateaus are studied in a brief time period with a servo-controlled system. The test determines the difference between rates of CSF absorption and formation as a function of pressure. On-line computer data analysis increases experimental efficiency to guarantee statistical significance. Animal and patient data are presented in the report.

Absorption↗