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Biomedical subjects

H H Davis

Publications and source records attributed to H H Davis.

At least 19 recordsLinked to original sources
PubMed2000

Acute mesenteric ischemia and malpractice claims.

BACKGROUND: Acute mesenteric ischemia can be a difficult diagnosis to make, but delay contributes directly to infarction, and this may provide a setting for malpractice claims. METHODS: We reviewed 180 consecutive malpractice claims submitted by attorneys for medical expert (ME) review during the 12 years ending in late 1998. Seven cases involved acute mesenteric ischemia. RESULTS: Alleged failure to make a timely diagnosis was the basis for 5 of these claims, failure to provide anticoagulant protection for 1, and failure to prevent nonocclusive ischemic infarction for 1. Six claims were closed after ME review and 1 claim involving late diagnosis was settled before trial. CONCLUSIONS: The risk of a malpractice claim is reduced by consideration of computed tomography (CT), angiography, and surgical consultation as soon as a patient is seen whose differential diagnosis includes acute mesenteric ischemia.

Acute Disease↗
PubMed1999

Necrotizing fasciitis and malpractice claims.

BACKGROUND: Necrotizing fasciitis (NF) is an aggressive bacterial infection of the superficial fascia and subcutaneous tissues that is increasing in incidence. The high toll exacted by this illness provides a setting for malpractice claims. METHOD: We reviewed 180 consecutive malpractice claims submitted by attorneys for medical expert review between 1987 and late 1997. Four cases involved NF. RESULTS: Alleged failure to obtain timely surgical consultation was the basis for three claims, and alleged failure to prevent NF by proper nursing care was the basis for the fourth. Three cases were closed and one was settled. CONCLUSIONS: The cornerstone of risk management for a clinical presentation compatible with NF is immediate surgical consultation, with other diagnostic steps a secondary consideration.

Adult↗
PubMed1998

Pulmonary embolism and malpractice claims.

BACKGROUND: Deep venous thrombosis (DVT) with pulmonary embolization (PE) often occurs as an unexpected event with fatal consequences. This provides a setting for malpractice claims. METHODS: We reviewed 160 consecutive malpractice claims submitted by attorneys for medical expert review during the 11-year period ending in 1997. Seven cases involved DVT with PE. RESULTS: Alleged failure to anticipate and reduce the chance of PE was the basis for six of the claims. All six patients were at risk for lower extremity DVT, and one had a history of DVT 6 months earlier. The PE was manifested by sudden death in three cases. The seventh case represented a complication of heparin therapy for PE. CONCLUSIONS: We conclude that risk management for PE should focus primarily on DVT. Physicians should perform and document an examination for DVT whenever there is a history of lower extremity stasis or it is likely to occur. They should also consider documenting a concurring second opinion when making anticoagulant-related decisions.

Adult↗
PubMed1994

Localization of insulin-like immunoreactivity in the synganglion of nymphal and adult Dermacentor variabilis (Acari: Ixodidae).

Immunocytochemical staining based on a peroxidase-antiperoxidase method showed neurosecretory cells (NSC) reactive to bovine insulin in five of 18 paraldehyde fuchsin-positive neurosecretory regions (NSR) in the synganglion of unfed adult Dermacentor variabilis. This is the first report of a neuropeptide in an ixodid tick. The insulin-specific immunoreactive cells included the posterior medial group of the protocerebral center, posterior group of dorsal opisthosomal center, anterior lateral group of the dorso-lateral cheliceral center, dorsal group of the frontal stomodeal center, and anterior group of the ventral palpal center. After feeding and mating, females no longer had immunoreactive cells in three of five NSR found in virgin, unfed females. However, two cells of the posterior group in dorsal opisthosomal center and anterior lateral group of the dorso-lateral cheliceral center remained immunoreactive throughout feeding. Fed, mated males continued to display immunoreactive cells in four of five NSR found in the virgin, unfed males. All developmental stages of nymphs examined had insulin-specific immunoreactive cells in two of the five NSR found in unfed adults, including two positively stained cells of the posterior group in dorsal opisthosomal center and anterior group of ventral palpal neurosecretory center.

Animals↗
PubMed1992

Hemolytic-uremic syndrome associated with ingestion of quinine.

Hemolytic-uremic syndrome following quinine ingestion is a newly described phenomenon, with just two previous descriptions of 4 cases in the literature. We describe a 5th case. The reaction may be mediated by the presence of antibodies reactive against platelets in the presence of quinine. Treatment has included use of plasma exchange, prednisone, aspirin, and dipyridamole. The patients have all regained some degree of renal function. However, it is unclear whether pharmacological treatment or spontaneous resolution is responsible for the improvement. Quinine-associated hemolytic-uremic syndrome probably occurs more often than is recognized. It is important to recognize this reaction when it occurs and to avoid further quinine exposure, since the reaction seems to be recurrent.

Biopsy↗
PubMed1982

Indium-111 platelet scintigraphy in cerebrovascular disease.

We obtained scintigraphic images of the neck from 100 patients with suspected cerebrovascular disease after injecting indium-111-labeled autologous platelets. One or more focuses of increased activity, implying local platelet accumulation, were seen along the course of the cervical carotid arteries in 52 patients. In 64 patients, there was a highly significant correlation between the results of scintigraphy and carotid arteriography (p = 10(6)). There was no significant correlation between the scintigraphic findings and the previous or subsequent occurrence of transient ischemic attack or cerebral infarction in the carotid circulation. These data suggest that factors other than the simple formation of platlet thrombi in the cervical carotid arteries are of primary importance in the pathogenesis of stroke.

Adult↗
PubMed1981

Ventilation imaging with Kr-81m. A comparison with Xe-133.

Sixty-five patients with suspected pulmonary embolism were studied prospectively with both Kr-81m and Xe-133 ventilation imaging and Tc-99m MAA perfusion imaging. The krypton images, perfusion scintigrams and chest radiographs were read independently of the xenon images, perfusion scintigrams and chest radiographs by three observers. The studies of 53 patients were interpreted as normal or as indicative of a low or intermediate probability for pulmonary embolism with both gases. One study indicated intermediate probability with Xe-133 due to diffuse, severe xenon retention but low probability with Kr-81m because of close ventilation-perfusion correspondence. The studies of 9 patients indicated a high probability of embolism with both gases, while those of two additional patients (one with emboli at angiography) indicated a high probability only with Kr-81m. While essential agreement between Xe-133 and Kr-81m ventilation imaging was found in most patients, the significant difference in interpretation in 2 of 11 patients with probable pulmonary embolism suggests that a controlled, prospective trial with pulmonary angiography is warranted before Kr-81m is employed for routine clinical use.

Humans↗
PubMed1980

Detection of accessory spleens with indium 111-labeled autologous platelets.

In two patients with recurrent immune thrombocytopenia, accessory splenic tissue was demonstrated by radionuclide imaging following administration of indium 111-labeled autologous platelets. In one of these patients, no accessory splenic tissue was seen on images obtained with technetium 99m sulfur colloid. This new technique provides a simple means for demonstrating accessory spleens and simultaneously evaluating the life-span of autologous platelets.

Adult↗
PubMed1980

111Indium-labeled human alveolar macrophages and monocytes: function and ultrastructure.

Human alveolar macrophages and peripheral blood mononuclear cells were labelled with indium-111 (111In)-oxine in ethanol. The efficiency of labeling averaged 84% for macrophages and 74% for mononuclear cell preparations. Phagocytosis by macrophages, the release of colony stimulating factor activity (CSF) by macrophages, and chemotaxis by monocytes in response to human C5-derived chemotactic factor (C5fr) and formyl-methionyl-leucyl-phenylalanine (f-MLP), were indistinguishable between labeled and unlabeled cells. Microscopically, labeled cells looked similar to control cells. Radioautography demonstrated 111In throughout the labeled cells, but there was a disproportionately high quantity over nuclei. These findings add to the growing literature indicating that 111In labels cells efficiently and that cells can retain function after being labeled with 111In.

Autoradiography↗
PubMed1980

Scintigraphy with 111In-labeled autologous platelets in venous thromboembolism.

Scintigraphy with 111in-labeled autologous platelets was performed in 20 patients with suspected venous thrombosis and/or pulmonary embolism. The platelets accumulated in venous thrombi in 6 or 7 patients (86%) with positive findings on impedance plethysmography or contrast venography; all 6 were receiving intravenous heparin. In 11 patients with pulmonary embolism diagnosed by ventilation--perfusion imaging or pulmonary angiography, platelet scintigraphy showed embolic uptake only in the one patient not on full-dose heparin. These findings suggest that scintigraphy with 111In-platelets is a promising noninvasive technique for detection of deep venous thrombosis. Heparin does not appear to block localization of labeled platelets in venous thrombi, but may inhibit their adherence to pulmonary emboli.

Adult↗
PubMed1980

Scintigraphic detection of carotid atherosclerosis with indium-111-labeled autologous platelets.

Using autologous platelets labeled with indium-111-oxine, we studied the localization of platelets on arterial lesions by radionuclide scintigraphy in 34 patients with suspected cerebrovascular disease. The imaging results were compared with the findings of contrast angiography in 23 patients, 16 of whom were receiving antiplatelet and/or anticoagulant drugs during the platelet imaging study. Angiography demonstrated atherosclerotic lesions at 33 sites in the extracranial arteries of 16 of these patients. There was accumulation of 111In-platelets at 20 of these sites (61%) and at three other sites without definite angiographic abnormalities. Lesions with stenoses less than 50% were slightly more frequent than those with greater stenosis (68% vs 45%). The frequency of true-positive scintigraphic results was slightly higher in patients not treated with antithrombotic agents than in those on such drugs (70% vs 57%). Our results suggest that imaging with 111In-labeled autologous platelets may be useful for evaluating the pathophysiologic characteristics of atherosclerotic lesions in patients with cerebrovascular disease.

Adult↗
PubMed1979

Indium-III: a new radionuclide label for studying human platelet kinetics.

Indium-III. when complexed with 8-hydroxyquinoline (oxine), has been employed as a radioactive platelet label for thrombus imaging in animals and man. The short half-life (2.8 d) and high yield of gamma photons of 111In make it ideal for in vitro counting and external imaging. To evaluate its suitability for studies of platelet turnover in man, platelet kinetic studies were carried out on 10 healthy volunteers using 111In-and 51Cr-platelets concurrently. For 111In labelling, platelets were harvested by differential centrifugation from 43 ml of whole blood drawn into acid-citrate dextrose (ACD) solution. The platelets were washed and suspended in a mixture of ACD and isotonic saline and then incubated with 111In-oxine, rewashed, and suspended in plasma for reinfusion. 51Cr labelling was performed using standard methods. Mean labelling efficiency was 73% with 111In and 6.5% with 51Cr. In vitro studies demonstrated minimal release, elution, and reutilization of the 111In label. There was no significant difference in the aggregation response of 111In- and 51Cr-platelets to ADP and collagen. The in vivo recovery of 111In-platelets was approximately 50% greater than that of 51Cr-platelets whereas the platelet life spans were similar. These results indicate that 111In labelled platelets may be useful for thromobokinetic studies in man. The new method offers the advantages of reduced blood requirements, higher labelling efficiency, and the ability to perform external imaging of platelet distribution in vivo.

Adult↗
PubMed1978

Scintigraphic detection of atherosclerotic lesions and venous thrombi in man by indium-111-labelled autologous platelets.

Accumulation of autologous platelets labelled with indium-111 at sites of atherosclerosis or venous thrombosis was demonstrated by scintigraphy in three patients. The lesions detected were bilateral ulcerated carotid-artery plaques, iliofemoral venous thrombosis, and renal-vein thrombosis. This technique shows promose as a non-invasive means of diagnosing focal atherosclerotic and thrombotic lesions.

Arteriosclerosis↗
PubMed1978

Alveolar-capillary oxygen disequilibrium in hepatic cirrhosis.

Hypoxemia is a frequent occurrence in patients with severe hepatic disease. Multiple mechanisms have been implicated in the production of such hypoxemia. The case of a 35-year-old man with cyanosis, clubbing, and cirrhosis is presented. Physiologic data from this patient revealed normal pulmonary function, except for a low diffusing capacity and a 28 percent shunt while the patient was breathing 100 percent oxygen. A perfusion scan with radioactive 99mtechnetium-labelled macroaggregated albumin revealed 67 percent of the labelled macroaggregated albumin in the systemic circulation. Post-mortem examination demonstrated normal pulmonary parenchyma, markedly dilated intraparenchymal capillaries and arterioles, subpleural angiomata, and cirrhosis. No anatomic arteriovenous connections were demonstrated before or after death. We conclude that the arterial hypoxemia of some patients with hepatic cirrhosis results from dilated gas-exchanging blood vessels. These widened vessels prevent end pulmonary capillary oxygen tension from reaching equilibrium with alveolar gas, perhaps because of the widened distance for diffusion.

Adult↗
PubMed1977

Scintigraphic diagnosis of experimental pulmonary embolism with In-111-labeled platelets.

Stasis thrombi, radiolabeled with Tc-99m sulfur colloid, were produced in six dogs by the injection of human thrombin into isolated jugular vein segments. After release of the thrombi, scintigraphic images demonstrated 16 pulmonary emboli containing Tc-99m. Autologous platelets labeled by the In-111 oxine method were injected. Sequential images demonstrated platelet accumulation in 14 of the 16 emboli within 1 hr. The emboli were recovered at autopsy and their activity assayed. The mean uptake of In-111-labeled platelets was 1.1% dose/g of embolus, and the mean embolus-to-blood ratio was 16. Our results demonstrate that fresh pulmonary emboli in dogs can be detected by imaging with In-111-labeled platelets, and suggest that radiolabeled platelets may provide a simple, noninvasive method for the direct visualization of pulmonary emboli in patients.

Animals↗