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Biomedical subjects

M D Morgan

Publications and source records attributed to M D Morgan.

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

Imaging of the nontraumatic acute abdomen.

Plain-film radiography of the abdomen is often the first-line imaging modality used for the patient in the ED. It is capable of demonstrating abnormal locations of gas, abnormal viscera, calcifications and foreign material, and skeletal and lower lung pathology. PFR findings may aid in the decision to proceed to other modalities. Contrast studies have a limited role in the ED but may be necessary to diagnose disease inadequately visualized by PFR, as in the case of perforated duodenal ulcer, missed on PFR in approximately 15 per cent of cases. Ultrasound is most useful in the ED for obstetric and gynecologic illness, as well as disorders of the hepatobiliary system. Nuclear medicine studies can be very useful for GI bleeding and inflammatory conditions but may not always be as available or convenient as other modalities. CT has very broad usefulness. Angiography is very useful for locating bleeding sites, especially in the large bowel, and for determination of mesenteric arterial patency in suspected mesenteric ischemia. Finally, MRI, which has enormous potential, is not funded by many third-party payment plans for use in emergencies, and must overcome certain obstacles before it assumes common usage in the ED.

Abdomen, Acute↗
PubMed1987

Sulfate reduction in peat from a new jersey pinelands cedar swamp.

Microbial sulfate reduction rates in acidic peat from a New Jersey Pine Barrens cedar swamp in 1986 were similar to sulfate reduction rates in freshwater lake sediments. The rates ranged from a low of 1.0 nmol cm day in February at 7.5- to 10.0-cm depth to 173.4 nmol cm day in July at 5.0- to 7.5-cm depth. The presence of living Sphagnum moss at the surface generally resulted in reduced rates of sulfate reduction. Pore water sulfate concentrations and water table height also apparently affected the sulfate reduction rate. Concentrations of sulfate in pore water were nearly always higher than those in surface water and groundwater, ranging from 26 to 522 muM. The elevated pore water sulfate levels did not result from the evapotranspiratory concentration of infiltrating stream water or groundwater, but probably resulted from oxidation of reduced sulfur compounds, hydrolysis of ester sulfates present in the peat, or both. The total sulfur content of peat that had no living moss at the surface was 164.64 +/- 1.5 and 195.8 +/- 21.7 mumol g (dry weight) for peat collected from 2.5 to 5.0 and 7.5 to 10.0 cm, respectively. Organosulfur compounds accounted for 84 to 88% of the total sulfur that was present in the peat. C-bonded sulfur accounted for 91 to 94% of the organic sulfur, with ester sulfate being only a minor constituent. Reduced inorganic sulfur species in peat from 2.5 to 7.5 cm were dominated by H(2)S-FeS (68%), while pyritic sulfide was the predominant inorganic sulfur species in the peat from depths of 7.5 to 10.0 cm (75%).

Journal Article↗
PubMed1986

Effects of postural drainage, incorporating the forced expiration technique, on pulmonary function in cystic fibrosis.

Detailed pulmonary function tests were performed on 12 patients with cystic fibrosis (CF) before and after 3 days treatment with postural drainage incorporating the forced expiration technique. The results following treatment showed a statistically significant improvement in FEV1 (P less than 0.001), FVC (P less than 0.001), PEFR(P less than 0.001), PIFR (P less than 0.001), and VEmax50 (P less than 0.025). The study demonstrates objective benefit from this form of physiotherapy in cystic fibrosis patients with copious bronchial secretions.

Adolescent↗
PubMed1986

Value of computed tomography for selecting patients with bullous lung disease for surgery.

Computed tomography and lung function tests were performed on 43 patients who had evidence on the chest radiograph suggesting bullous emphysema. After computed tomography scan two groups of patients could be identified. Twenty patients had generalised emphysema, which was locally worse in the area of the suspected bulla; and 23 had well defined bullae, which were potentially operable. Results of lung function tests did not distinguish between the two groups. The volume and ventilation of the true bullae were measured by computed tomography and this confirmed that most of them did not contribute to ventilation (residual volume (RV)/total capacity (TLC) bulla = 89% (SD 10%). The patients with true bullae were considered suitable for surgery but only 12 had an operation. All the patients who underwent surgery survived and had a symptomatic improvement, which was accompanied by objective increases in spirometric volumes and by reductions in static lung volumes; there were no improvements in carbon monoxide transfer or blood gas tensions. It is concluded that computed tomography used alone can identify bullae that are amen-able to surgery and can measure their volume and ventilation. The surgical removal of such clearly identified bullae is safe and associated with symptomatic and functional improvement even when the preoperative FEV1 is less than 1 litre. This improvement is likely to be a consequence of reduction in lung volume and may not necessarily be associated with relief of compressed peribullous lung or the removal of dead space.

Forced Expiratory Volume↗
PubMed1986

Measurement of abdominal wall compliance in normal subjects and tetraplegic patients.

On inspiration descent of the diaphragm is opposed by the passive properties of the abdominal wall, the tone of its muscles, and the inertia of the abdominal contents. As a result, intra-abdominal pressure rises and promotes rib cage expansion. In patients with high spinal injury the diaphragm is the most important muscle of inspiration and abdominal wall displacement is more evident than in normal subjects. Abdominal wall compliance has been measured by relating gastric pressure to abdominal wall displacement, which was determined by means of an optical contour mapping system. Six normal subjects and six tetraplegic patients were studied in the supine posture, during passive expiration from total lung capacity to functional residual capacity. Over this lung volume range the normal subjects partitioned an average of 31% of expired volume to the abdominal compartment, while the corresponding average figure in the patients was 77% of expired volume. Since the range of gastric pressure was similar in the two groups, it is concluded that abdominal wall compliance is greater in tetraplegic patients. This high compliance could have a detrimental effect on lower rib cage expansion.

Abdominal Muscles↗
PubMed1986

Estimation of regional gas and tissue volumes of the lung in supine man using computed tomography.

This study was intended to discover how well computed tomography could recover the volume and weight of lung like foams in a body like shell, and then how well it could recover the volume and weight of the lungs in supine man. Model thoraces were made with various loaves of bread submerged in water. Computed tomography scans recovered the volume of the model lungs (true volume range 250-12,500 ml) within +0.2 (SD 68) ml and their weights (true range 72-3125 g) within +30 (78) g. Scans also recovered successive injections of 50 ml of water, within +/- 5 ml. Scans in 12 healthy supine men recovered their vital capacities, total lung capacities (TLC), and predicted tissue volumes with comparable accuracy. At total lung capacity the mean tissue volume of single lungs was 431 (64) ml and at residual volume (RV) it was 427 (63) ml. Tissue volume was then used to match inspiratory and expiratory slices and calculate regional ventilation. Throughout the mid 90% of lung the RV/TLC ratio was fairly constant--mean 21% (5%). New methods of presenting such regional data graphically and automatically are also described.

Adult↗
PubMed1985

Contribution of the rib cage to breathing in tetraplegia.

In tetraplegia there is often paradoxical inward motion of the rib cage during inspiration. The volume of this negative contribution is difficult to estimate but can be obtained by optical mapping. The partitioning of ventilation between the rib cage and abdomen in six normal subjects, 10 stable tetraplegic patients, and one tetraplegic patient at intervals during rehabilitation has been studied by this technique. In normal subjects the tidal volume and the vital capacity were the sum of positive contributions from the rib cage and abdomen. In stable tetraplegic subjects with similar neurological levels, the rib cage contribution varied widely but the total chest wall displacement could not be predicted from the vital capacity. In the patient studied sequentially rib cage paradox reversed with time after injury, and this was associated with an absolute increase in vital capacity and an improvement in the action of the diaphragm.

Adolescent↗
PubMed1984

Analysis of an optical mapping technique for lung function studies.

An optical technique for lung function measurement studies is described and analysed. Procedures which permit the reconstruction of three dimensional data concerning the thoraco-abdominal wall are developed and methods for calculating volumes, surface areas and cross-sections are outlined.

Humans↗
PubMed1984

An optical method of studying the shape and movement of the chest wall in recumbent patients.

A method of optical mapping has been developed that allows the shape and motion of the chest wall to be studied in recumbent patients. It uses a single camera at a fixed viewpoint to determine the three dimensional coordinates of the visible surface of the body, and hence to measure the volume and shape of the visible segment. Measurements on different test objects (volumes 228-7807 ml) in different positions suggest a reproducibility of volume measurement of +/- 26 ml (SD) and a maximum volume error of 150 ml. Studies of computed tomography scans in inspiration and expiration show that it should be possible to capture 97% of respiratory motion by this method. The mean difference between optical and spirometric measurements of expired volume in six subjects was 0.25 (SD 0.2) 1. Within subject systematic errors of up to 10% were noted. The mean deviation about the regression line of optically measured expired volume on spirometric expired volume varied from 68 to 243 ml in the six subjects (mean 131 (SD 92) ml). To examine the potential of the optical technique, for rapid data acquisition it was used to construct a 24 point flow volume loop from a normal subject.

Anthropometry↗
PubMed1984

Optical mapping of the thoracoabdominal wall.

An optical technique has been developed for mapping the size and shape of the thoracoabdominal wall and the change in its shape with breathing. A fixed pattern composed of stripes of light is projected on to both sides of the trunk. These stripes become distorted when viewed from in front and behind, forming contours over the trunk surface. The contours are photographed and then encoded digitally. The digital information can be used to compute automatically the volume of the trunk, the position of any point on its surface, and its cross sectional shape at any level. The technique has been tested on rigid objects (a globe, a cone, and two dummy torsos) that can be measured precisely. With this optical technique linear dimensions can be calculated to within 0.5 mm, cross sectional area to within 5%, and volume to within 1.6-3.7%. These results suggest that this non-invasive technique measures the shape and volume of complex three dimensional surfaces with sufficient accuracy to be tried in clinical practice.

Abdominal Muscles↗
PubMed1984

Computed tomography in the assessment of bullous lung disease.

The assessment of bullous lung disease with respect to possible surgical treatment requires anatomical and functional information about the extent of disease and the mechanism of symptom production. It is also important to measure the function of non-bullous lung and to make some prediction of the behaviour of non-bullous lung after resection of bullae. We have used computed tomography during inspiration and expiration together with bronchoscopic single-breath inert gas techniques of regional lung function to assess such patients. Computed tomography clearly demonstrates the extent and distribution of bullous disease while both the computed tomography and the bronchoscopic argon/freon test give functional information about bullous and non-bullous lung. In our experience computed tomography improves the assessment of bullous lung disease.

Humans↗
PubMed1983

The treatment of quinine poisoning with charcoal haemoperfusion.

Quinine poisoning is rare but serious. Attempts at treatment by active removal have proved unsuccessful because of its high degree of protein binding. We describe two cases of non-accidental overdose of quinine (19.5 g and 15 g) with potentially fatal serum quinine levels. Both patients were treated by 2 periods of charcoal haemoperfusion during which quinine clearances of up to 125 ml/min were obtained. Both patients recovered, though one had some residual visual disturbance. We suggest that in cases of quinine poisoning, charcoal haemoperfusion may be a safe and effective method of drug removal, to be used with stellate ganglion block.

Adult↗