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Biomedical subjects

P A Hamilton

Publications and source records attributed to P A Hamilton.

At least 19 recordsLinked to original sources
PubMed1996

A comparison of low-dose heparin with low-molecular-weight heparin as prophylaxis against venous thromboembolism after major trauma.

BACKGROUND: Patients who have had major trauma are at very high risk for venous thromboembolism if they do not receive thromboprophylaxis. We compared low-dose heparin and a low-molecular-weight heparin with regard to efficacy and safety in a randomized clinical trial in patients with trauma. METHODS: Consecutive adult patients admitted to a trauma center who had Injury Severity Scores of at least 9 and no intracranial bleeding were randomly assigned to heparin (5000 units) or enoxaprin (30 mg), each given subcutaneously every 12 hours in a double-blind manner, beginning within 36 hours after the injury. The primary outcome was deep-vein thrombosis as assessed by contrast venography performed on or before day 14 after randomization. RESULTS: Among 344 randomized patients, 136 who received low-dose heparin and 129 who received enoxaparin had venograms adequate for analysis. Sixty patients given heparin (44 percent) and 40 patients given enoxaparin (31 percent) had deep-vein thrombosis (P=0.014). The rates of proximal-vein thrombosis were 15 percent and 6 percent, respectively (P=0.012). The reductions in risk with enoxaparin as compared with heparin were 30 percent (95 percent confidence interval, 4 to 50 percent) for all deep-vein thrombosis and 58 percent (95 percent confidence interval, 12 to 87 percent) for proximal-vein thrombosis. Only six patients (1.7 percent) had major bleeding (one in the heparin group and five in the enoxaparin group, P=0.12). CONCLUSIONS: Low-molecular-weight heparin was more effective than low-dose heparin in preventing venous thromboembolism after major trauma. Both interventions were safe.

Adult↗
PubMed1996

Identifying maculopathy after neodymium: YAG membranotomy for dense diabetic premacular hemorrhage.

PURPOSE: To assess the value of neodymium:YAG membranotomy in achieving rapid intravitreal dispersion of dense diabetic premacular hemorrhage and allowing the identification and treatment of maculopathy before panretinal photocoagulation (PRP). METHODS: A pilot study, in which nine eyes with dense diabetic premacular hemorrhages were treated with neodymium:YAG membranotomy, is described. After intravitreal dispersion of premacular blood, fundus examination and fluorescein angiography were performed to identify neovascularization and macular edema. Macular photocoagulation was performed before PRP in eyes with co-existing maculopathy and neovascularization. RESULTS: Complete intravitreal dispersion was achieved in all eyes within 1 week. Clinically significant macular edema was identified and treated, before PRP, in three eyes. No exacerbation of macular edema occurred after PRP, and visual acuity was stabilized at pre-hemorrhage levels in seven eyes and to within one line in the remaining two eyes. No traction retinal detachments or rebleeding occurred, and vitrectomy was not required in any eye. CONCLUSIONS: Early neodymium:YAG membranotomy may obviate the need for early vitrectomy for dense diabetic premacular hemorrhage, and allows early identification and treatment of maculopathy, before PRP, thus reducing the risk of exacerbation after PRP. Further studies to evaluate this treatment modality, particularly with respect to long-term visual prognosis, appear warranted.

Adult↗
PubMed1996

Nasal deformities resulting from flow driver continuous positive airway pressure.

Over a period of six months, seven cases were documented of trauma to the nose as a result of flow driver continuous positive airway pressure in babies of very low birthweight (VLBW). There was a complication rate of 20% in the babies who required it. Deformities consisted of columella nasi necrosis which can occur within three days, flaring of nostrils which worsens with duration of continuous positive airway pressure, and snubbing of the nose which persists after prolonged continuous positive airway pressure. These complications should be preventable by modifications to the mechanism and method of use.

Humans↗
PubMed1995

Diode laser contact transscleral retinal photocoagulation: a clinical study.

AIM: To examine the clinical efficacy of contact transscleral retinal photocoagulation with a diode laser. METHODS: Transscleral retinal photocoagulation was performed on 36 eyes. The conditions treated included peripheral retinal breaks associated with retinal detachments (30 eyes) and giant retinal tears (six eyes). Of the 30 eyes with retinal detachments, 28 underwent transscleral photocoagulation to the site of drainage of subretinal fluid in an attempt to reduce the risk of hemorrhage. RESULTS: Threshold lesions were obtained with irradiances of between 95.4 W/cm2 and 191 W/cm2. Satisfactory chorioretinal adhesion was achieved in all eyes with retinal breaks and giant retinal tears. The only significant complications of treatment encountered were punctate choroidal haemorrhages (three eyes). Drainage related choroidal haemorrhage following earlier photocoagulation occurred in two of 28 eyes. CONCLUSIONS: This study confirms the clinical potential of transscleral diode laser photocoagulation in the therapy of surgical retinal conditions.

Adolescent↗
PubMed1995

Needle size and sample adequacy in ultrasound-guided biopsy of thyroid nodules.

OBJECTIVES: To determine the optimal needle size (23-gauge or 27-gauge) for ultrasound-guided fine-needle aspiration biopsy of thyroid nodules and to compare the interoperator yield for this procedure. PATIENTS AND METHOD: Over an 11-month period, 123 patients underwent biopsy of a thyroid nodule. Three experienced radiologists were assigned at random to sample the nodules. For each nodule, four passes were performed in random order, two with 23-gauge needles and two with 27-gauge needles. If a specific pass yielded no tissue or blood, as determined by visual inspection (i.e., the sample was dry), the procedure was repeated until a satisfactory sample was obtained. After each patient had left the department, the aspirates were reviewed by a cytopathologist (who was not aware of needle size or operator identity) to determine diagnostic adequacy. RESULTS: Among the 123 nodules, 88 were solid, and 35 were complex cysts. There was no significant difference between the two sizes of needle in the adequacy of the samples obtained (102 nodules were adequately sampled with the 23-gauge needle and 95 with the 27-gauge needle; McNemar chi 2 test, p = 0.1456). However, there were significantly fewer dry passes with the larger needle (2 with the 23-gauge needle and 16 with the 27-gauge needle; chi 2 test, p = 0.0022). Sixteen nodules were inadequately sampled with both needles. Eight of these were less than 1 cm in greatest dimension. Only one solid nodule greater than 1 cm in greatest dimension was inadequately sampled. There was no difference in yield among the three radiologists (chi 2 test, p = 0.5192). No significant complications were encountered. CONCLUSIONS: Needles of both 23 and 27 gauge can be used to obtain fine-needle aspiration biopsy samples from thyroid nodules. Using both sizes is recommended, because the number of dry passes is lower with the larger needle, but the diagnostic quality of the aspirate may be better with the smaller one. Experienced physicians can perform fine-needle aspiration biopsy with equal proficiency.

Adult↗
PubMed1994

Plasma interleukin-6 and tumour necrosis factor levels as predictors of disease severity and outcome in necrotizing enterocolitis.

Plasma tumour necrosis factor (TNF) and interleukin-6 (IL-6) levels of 18 infants with necrotizing enterocolitis (NEC) were measured at the time of diagnosis or on transfer to a paediatric surgical unit. Whereas TNF levels were similar for infants managed medically (stage II, n = 8) and surgically (stage III, n = 7), IL-6 levels were significantly higher in stage III cases (mean, 3,127 pg/mL [95% CI, 1,809 to 4,445 pg/mL]) than in stage II (mean, 127 pg/mL [95% CI, 10 to 329 pg/mL]; P = .001). Neither TNF nor IL-6 level predicted eventual outcome. Plasma IL-6 may be useful as an indication for operation in NEC.

Biomarkers↗
PubMed1994

Plasma cytokine levels in necrotizing enterocolitis.

Plasma concentrations of tumour necrosis factor (TNF) and interleukin-6 (IL-6) were measured by ELISA in samples taken from 24 infants with necrotizing enterocolitis (NEC) between 0 and 306 h from diagnosis. TNF was detected (> 10 pg/ml) in 71% samples with a mean of 48 pg/ml (95% CI 42 to 55 pg/ml) and did not vary with either time from diagnosis or severity of disease. IL-6 was raised during the first 48 h with a significant difference between stage II (mean 127 pg/ml, 95% CI 10 to 329 pg/ml) and stage III (mean 3127 pg/ml, 95% CI 1809 to 4445 pg/ml, p = 0.001). Postoperative plasma IL-6 concentration fell to similar levels seen in stage II (mean 150 pg/ml, 95% CI 37 to 283 pg/ml, p = 0.79). We conclude that plasma concentration of IL-6 rather than TNF reflects the clinical severity of necrotizing enterocolitis and that the relative level of these cytokines has important implications for the use of anti-cytokine therapy in NEC.

Biomarkers↗
PubMed1994

Necrotizing enterocolitis--multisystem organ failure of the newborn?

Evidence of failure of organ system other than the gastrointestinal tract was reviewed in a series of 46 infants treated for necrotizing enterocolitis (NEC) at a regional combined medical and surgical neonatal unit. Respiratory failure was identified in 42 infants (91%), renal failure in 39 (85%), cardiovascular failure in 15 (33%) and hepatic failure in 7 (15%). The number of systems involved correlated with both severity of disease and outcome. Onset of failure in the above systems was closely related to the diagnosis of NEC and 29 cases predated the clinical onset. We conclude that NEC is part of a syndrome of multisystem failure and that this has important implications for the treatment of NEC.

Cytokines↗
PubMed1993

Membranoproliferative glomerulonephritis type II associated with central serous retinopathy.

Membranoproliferative glomerulonephritis type II is specifically associated with the presence of dense deposits in the basement membrane of Bruch's membrane, which result in lesions similar to basal laminar drusen, exudative drusen, and retinal pigment epithelial detachments. In advanced stages of this dense-deposit retinopathy, choroidal neovascularization may occur. We observed a 36-year-old patient with membranoproliferative glomerulonephritis type II who developed central serous retinopathy in the presence of specific dense-deposit-associated fundus lesions. The diffuse drusenlike dense deposits (at the level of Bruch's membrane) and associated retinal pigment epithelial detachments appear to contribute to the pathogenesis of central serous retinopathy. Thus changes in Bruch's membrane may be involved in the development of central serous retinopathy.

Adult↗
PubMed1993

Anterior hyaloidal fibrovascular proliferation after extracapsular cataract extraction in diabetic eyes.

Four patients with proliferative diabetic retinopathy developed anterior hyaloidal fibrovascular proliferation after extracapsular cataract extraction and posterior chamber lens implantation. This complication of cataract extraction has been described after vitrectomy in diabetic eyes. Risk factors for this entity after extracapsular cataract extraction include proliferative diabetic retinopathy, iris neovascularization, and anterior ischemic retina. Anterior hyaloidal fibrovascular proliferation was observed an average of 12 months postoperatively and affected vision in one of four patients. No progression was seen within an average of six months of follow-up, and no complications such as traction retinal detachment and vitreous hemorrhage developed.

Aged↗
PubMed1993

Extracapsular cataract extraction in proliferative diabetic retinopathy.

PURPOSE: To establish the visual prognosis, prevalence of complications, and optimal strategy for management of proliferative diabetic retinopathy (PDR) in isolated extracapsular cataract extraction (ECCE). METHOD: This is a retrospective review of 56 patients with PDR who underwent ECCE with lens implantation. Results were compared with 64 patients with background diabetic retinopathy (BDR) operated on during the same time period. RESULTS: Final visual acuity (67% > or = 20/40) was better in BDR eyes compared with PDR eyes (21% > or = 20/40; P < 0.001). In eyes without maculopathy, 94% with BDR achieved a final visual acuity of at least 20/40 compared with 52% with quiescent proliferative retinopathy (P < 0.001). Final visual acuity in eyes with maculopathy was better in BDR eyes (36% > or = 20/40) than in PDR eyes (5% > or = 20/40) (P < 0.02). No patient with active proliferative or preproliferative retinopathy achieved a final visual acuity of more than 20/80. Postoperative deterioration of retinopathy occurred in 50% of patients with active proliferative retinopathy compared with 10% with quiescent proliferative retinopathy (P < 0.01) and 3% with BDR (P < 0.001). Immediate postoperative fibrinous anterior uveitis, which prevented early panretinal photocoagulation, developed in over half the patients with active proliferative retinopathy. CONCLUSIONS: Final visual acuity after cataract extraction in diabetic patients with proliferative retinopathy is generally poor; however, in patients with quiescent proliferative retinopathy and no maculopathy, visual acuity may be good. Active proliferative retinopathy at the time of surgery is a poor prognostic indicator for final visual acuity and is associated with postoperative deterioration of retinopathy and fibrinous uveitis, which may preclude immediate postoperative panretinal photocoagulation.

Adult↗
PubMed1992

The relationship of ideology to developing community health nursing theory.

Ideology plays a major role in developing theory, guiding education, and directing practice in nursing. This study investigated the opinions of community health nurse educators regarding specific elements of community health nursing ideology and its relationship to the educators' opinions about the appropriateness of existing theory for professional use. The majority of participants agreed that a specific set of beliefs can be called a community health nursing ideology. Covariant factor analysis indicated that it is not a undimensional, internally consistent single set of beliefs or values, but rather is a set of two types of values, one focusing on the individual and the other on society. Individually oriented beliefs were positively related to satisfaction with existing theory. Socially oriented beliefs were negatively related to satisfaction with existing theory, but the relationship was not statistically significant. Anyone engaged in developing community health nursing theory would do well to consider which ideologic model is undergirding the process.

Attitude↗
PubMed1992

Atrial natriuretic peptide in the diagnosis of patent ductus arteriosus.

The aim of this study was to measure plasma atrial natriuretic peptide in preterm infants with a patent ductus arteriosus before and after closure with indomethacin. Atrial natriuretic peptide was measured in 28 preterm infants with clinical and echocardiographic evidence of a patent ductus arteriosus and in eight preterm infants who did not develop clinical evidence of a patent ductus arteriosus. Plasma concentration of atrial natriuretic peptide was measured by radioimmunoassay. In 18 infants the patent ductus arteriosus closed after one course of indomethacin; atrial natriuretic peptide levels decreased from median 1240 pg/ml (range 201-5483 pg/ml) to 266 pg/ml (range 62-1108 pg/ml). In four infants the patent ductus arteriosus closed after two courses of indomethacin and two infants had surgical ligation after indomethacin treatment failed. The patent ductus arteriosus closed spontaneously in four infants (atrial natriuretic peptide median level 152 pg/ml, range 61-495 pg/ml). In the eight infants without patent ductus arteriosus, atrial natriuretic peptide level was median 224 pg/ml (range 38-876 pg/ml). Measurement of plasma atrial natriuretic peptide concentration has a role in predicting when indomethacin treatment is indicated.

Atrial Natriuretic Factor↗
PubMed1992

Modified indirect hemagglutination test for detection of treponemal antibodies in finger-prick blood.

A modified indirect hemagglutination test for the detection of treponemal antibodies was developed for use with finger-prick blood. By using paired serum and absorbed finger-prick blood from 58 patients from an area previously endemic for yaws and 12 patients without yaws, the modified hemagglutination test was compared with a hemagglutination test for Treponema pallidum and the fluorescent treponemal antibody absorption test. The modified hemagglutination test showed 100% specificity and an overall agreement of 96.5% with the hemagglutination test for T. pallidum and 94.8% with the fluorescent treponemal antibody test. The modified hemagglutination test appears to be a simple and economical test that is suitable for use in large epidemiological surveys for yaws.

Adult↗
PubMed1992

Mediastinal large-cell lymphoma.

The records of 20 patients with pathologically diagnosed mediastinal large-cell lymphoma with sclerosis, a recently documented but uncommon subtype of mediastinal non-Hodgkin's lymphoma, were retrospectively reviewed to determine the clinical and radiologic features of the condition at the time of presentation. The disease was staged according to the Ann Arbor classification: 15 patients presented in clinical stage I or II and 5 in clinical stage III or IV. The patients, 6 women and 14 men, ranged in age from 15 to 63 years (mean = 31 years). Chest pain (experienced by 10 patients), dyspnea (by 9) and cough (by 7) were the most common clinical features. Obstruction of the superior vena cava occurred in seven patients. The mediastinal masses were large (the mean diameter was 10.8 cm) and located anteriorly (prevascularly). They contained low-attenuation areas and were often associated with other sites of mediastinal adenopathy. The initial pathologic diagnosis was incorrect for eight patients (40%). Mediastinal large-cell lymphoma can be added to the differential diagnosis of a large anterior mediastinal mass with obstruction of the superior vena cava.

Adolescent↗
PubMed1992

Ultrastructural changes of human trabecular meshwork after photocoagulation with a diode laser.

A diode laser, which emitted infrared radiation at a wavelength of 810 nm, was used to perform trabecular photocoagulation in a human eye due for enucleation for malignant melanoma. For comparison, burns were applied with an argon blue-green laser (488-514.5 nm). With each laser, the treatment spot size was 100 microns and the pulse duration was 0.20 sec. Visible lesions were produced with a power of between 750 mW and 1.2 W with the diode laser, and 500-900 mW with the argon laser. The pattern of damage produced by both modalities was similar and essentially consisted of contraction or expansion of trabecular beams, with trabecular destruction occurring only in relation to high power exposures. These findings confirm that trabecular photocoagulation is not a process that depends upon the wavelength of the incident energy at the two spectral extremes of 488 nm and 810 nm.

Aged↗