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Biomedical subjects

M H Reid

Publications and source records attributed to M H Reid.

At least 37 records · Page 2Linked to original sources
PubMed1981

Pancreatic sonography in cystic fibrosis.

Sonographic examination of the abdomen was performed in 20 patients with cystic fibrosis aged 3--41 years. The predominant acoustic architecture of the pancreas was one of moderate to markedly increased echogenicity when compared to the liver at the same depth. Increased echogenicity of the pancreas was independent of the presence of malabsorption. The usual reduced echo pattern associated with pancreatic inflammation was seen in only one of five cystic fibrosis patients with clinical evidence of pancreatitis. Other pancreatic abnormalities included pancreatic calcifications in one child with pancreatitis and a pseudocyst in an adult with pancreatitis. Eight patients had hepatosplenomegaly and gallstones were seen in two; one had a markedly contracted gallbladder. Sonography offers an effective method of following patients with cystic fibrosis.

Adolescent↗
PubMed1980

The anechoic retroplacental area: a pitfall in diagnosis of placental--endometrial abnormalities during pregnancy.

A total of 116 consecutive obstetric ultrasound examinations were reviewed. An anechoic area was observed at the placental-endometrial junctionin all 54 fundal placentas, 51 of the 52 posterior placentas, and 9 of the 36 anterior placentas. Detail was enhanced by use of a focused transducer with digital gray-scale equipment, and visualization of anterior placentas was improved by placing a water bath between the transducer and the skin surface. The anechoic area was seen beginning in the twelfth week of gestation and corresponds best to the dilated vessels of the decidua basalis.

Abruptio Placentae↗
PubMed1980

Improved ultrasound image detail using wide aperture, focused transducers.

Image resolution of anatomic parts located 3--4 cm below the skin surface can be improved with current digital B-scanners and a large aperture, high frequency, focused transducer. Such a transducer that has a very sharp focus over a limited depth of focus is described. The width of the field of view is unlimited, and image detail approaches that obtained with specialized real time scanners, although performance of the examination may not be as convenient or rapid. Examples of improved resolution are given for the thyroid, carotid artery, infant pancreas, ovary, and placenta.

Adenoma↗
PubMed1980

Noninvasive measurement of fetal and neonatal blood flow.

A newly developed doppler ultrasound flow measuring instrument was applied to determination of aortic arch blood flow in 6 near-term fetuses and 2 neonates and to umbilical cord flow in 2 fetuses. The method and results are presented and indicate good agreement between this noninvasive technique and expected values for aortic arch flow in human fetuses and neonates.

Aorta, Thoracic↗
PubMed1979

Statistical detection of nonvisible isodense subdural fluid collections.

An analytic method for detecting isodense subdural fluid collections from computed tomography (CT) scan pixel attenuation data is presented. Analysis of 44 CT scan levels from 8 patients with isodense subdural hematomas (ISDH) and 50 CT scan levels from 15 patients without ISDH indicates 6% false positive and 3% false negative errors if the analysis is restricted to noncontrast CT scans that demonstrate subcalvarial bilateral cortical attenuation symmetry in the pictorial display.

Atrophy↗
PubMed1979

Determination of blood flow through arteriovenous fistulae and shunts.

A videodensitometric method for estimating relative flow was employed in a patient with a bovine arteriovenous fistula. Analogous arteriovenous communications of different sizes were created in two dogs for comparison. Local and general hemodynamic parameters were measured. The videodensitometric method proved to be highly accurate compared to electromagnetic flow readings and is the method of choice in estimating shunt flow in connection with routine angiography.

Absorptiometry, Photon↗
PubMed1976

Visualization of the bile ducts using focused ultrasound.

The feasibility of using focused ultrasound for studying structures as small as biliary ducts and correlative radiological and ultrasonic studies of the common and larger hepatic ducts are presented. Patients whose bile ducts were visualized on intravenous or T-tube cholangiography or oral cholecystography underwent radiography with a metallic skin marker along the right anterior lower costal margin. The marker was then correlated with ultrasonic observations of multiple oblique scans parallel to the lower costal margin. The common duct could be identified in 15 of 21 patients. Ultrasonic visualization circumvents the problems of elevated serum bilirubin, iodine contrast media sensitivity, and pregnancy.

Bile Ducts↗
PubMed1973

Indicator dilution measurements of lung volumes and alveolar air exchange during breathing.

A new triple tracer indicator dilution technique has been used to measure alveolar ventilation as well as air and tissue volumes in the lungs of experimental animals and man. The tracers indocyanine green, [(121)I]antipyrine and xenon-133 were rapidly injected into the right atrium, while sampling was carried out from a peripheral artery. Blood flow and tissue volumes were obtained by classical analysis of the indocyanine green and antipyrine concentration-time curves. A double exit-port, constant air flow model was used to analyze the xenon curves, because ventilatory loss led to incomplete recovery of the gas tracer in effluent blood. Uniform ventilation and perfusion were assumed. This analysis permitted calculation of alveolar ventilation (VA(Xe)) and functional residual capacity (FRC(Xe)) during normal breathing. In control studies, VA(Xe) was similar to VA(co2), obtained with the steady-state CO(2) method (r = 0.87), while in critically ill patients the xenon measurement was significantly lower, averaging 54% of VA(co2). In theory, underestimates in VA(Xe) and decrease in the ratio VA(Xe)/VA(co2) relate to nonuniformity in regional ventilation and perfusion. The effect is greatest for the slightly soluble gas, xenon. The significant inverse correlation between VA(Xe)/VA(co2) and the physiologic shunt is consistent with this postulate.FRC(Xe) was similar to the predicted FRC in animals but was 76% of the helium measured FRC in patients. FRC(Xe) was significantly lower than the xenon measured air volumes during breath-holding when nonuniformity of ventilation was not operative. Lung tissue volumes in animals were 83% of gravimetric lung weights, while in patients the volumes were much lower than predicted. Nonhomogeneous lung function, including failure to perfuse the entire capillary bed, with resultant incomplete penetration of tracers into all segments of lung air and tissue, may explain these findings. The resultant errors can be significant in sick patients, and may themselves be used to study nonhomogeneities in the distribution of ventilation and volume.

Adult↗
PubMedDate not supplied

The human factors implications of peritoneal dialysis: cycler overfill incident reports.

Serious errors can occur with many medical devices (e.g., infusion pumps, ventilators, anesthesia machines), and even highly trained professionals can make critical errors. The FDA now requires that manufacturers consider the user when designing medical equipment and has issued a guidance document describing human factor (HF) problems and the HF design process. The Association for Advancement of Medical Instrumentation has also published guidelines, and the American Medical Association's National Patient Safety Foundation has selected reduction of medical errors as their mission. It is important that the medical community reinforce the patient-safety initiative by evaluating user-interface design and instructional manuals when purchasing such equipment. The payoff will be fewer incidents and less time required in device training. The FDA actively solicits help in identifying and reporting adverse events associated with medical devices. Health care practitioners employed by facilities subject to the FDA's user-facility reporting requirements should follow the user-reporting procedures established by their facility. Practitioners and users may want to directly report an incident to the MedWatch Program, the FDA's voluntary Medical Products Reporting Program.

Aged↗
PubMedDate not supplied

New videodensitometric method for measuring renal artery blood flow at routine arteriography: validation in the canine model.

A contrast medium was injected in the aortic arch and selectively in a renal artery to estimate the renal blood flow as a percentage of the cardiac output by the videodensitometric (VD) method. Twenty-six paired VD measurements in four mongrel dogs were obtained and the results compared to electromagnetic (EM) flow readings from the aortic arch and a renal artery. The relative renal blood flow estimated by the VD method averaged 9.1% and correlated with the EM flow average of 9.6% with r = 0.96. Previous in vitro investigations of relative flow in a model have now been validated in vivo. These results suggest that videodensitometry could be a clinical tool for measuring renal blood flow in conjunction with routine arteriography.

Absorptiometry, Photon↗
PubMedDate not supplied

A new tumor model for angiographic investigations: feline sarcoma virus tumor induction in adult cats.

This article describes the first successful virus induction of sarcomas in adult immunosuppressed cats. The method of tumor induction, the immunosuppression regimen, and the gross, histologic, and angiographic findings in these induced sarcomas are described. The simplicity of the model, the rapid and reliable growth of the tumors, and the size of the animals permit repeated angiography. The model is well suited to studies of angiographically directed therapy with embolic agents, radioactive implants, or chemotherapeutic drugs. The use of a feline model permits repeated selective angiography, which is not the case with small laboratory animals, in which such studies are difficult. In this investigation, tumors were induced into the right hepatic lobe because of the relative homogeneity of peripheral hepatic vascularity and the ease with which early neoplastic changes can be detected. There is good evidence to indicate that virus induction sites in other organs would also be successful.

Angiography↗