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Biomedical subjects

P Hamilton

Publications and source records attributed to P Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed2000

Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes.

OBJECTIVE: To examine the influence of caffeine on the frequency and perception of hypoglycemia in "free-living" patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 34 patients with type 1 diabetes were recruited for a prospective randomized placebo-controlled double-blind study. After a lead-in phase and while adhering to a low-caffeine diet, subjects were randomized to capsules containing either 200 mg caffeine or matched placebo with crossover at 3 months. Hypoglycemic episodes were monitored throughout with capillary blood glucose readings and a symptom questionnaire. During the study, measurements of blood pressure, middle cerebral artery blood velocity (a surrogate measure of cerebral blood flow), cognitive function (via a four-choice reaction time test), HbAlc levels, and lipid profiles were taken at the beginning and end of each phase. RESULTS: Throughout the study, no changes were evident regarding glycemic control or lipid profile. The number of symptomatic episodes was greater with caffeine (1.3 vs. 0.9 episodes/week; P < 0.03) and was associated with more intense warning symptoms (29 vs. 26 total symptom score; P < 0.05). For women, caffeine ingestion caused a modest pressor response (115 vs. 110 mmHg; P < 0.01). Four-choice reaction time improved slightly with caffeine supplementation (P < 0.05). CONCLUSIONS: Ingestion of modest amounts of caffeine enhances the intensity of hypoglycemia warning symptoms in patients with type 1 diabetes without altering the prevailing standard of glycemic control or increasing the incidence of severe hypoglycemic episodes.

Adult↗
PubMed1999

Early detection of arterial bleeding in acute pelvic trauma.

OBJECTIVE: To determine the accuracy of intravenous contrast-enhanced computerized tomography (CECT) in the detection of potentially life-threatening retroperitoneal hemorrhage in patients sustaining pelvic fractures, acetabular fractures or both. DESIGN: Retrospective review of sequential patients identified over a 1-year period by using a prospectively collected trauma database at two Level I trauma centers. MATERIALS AND METHODS: A group of patients admitted to one of two Level I trauma centers with pelvic or acetabular injuries between September 1, 1995, and September 30, 1996, was identified by using a prospectively collected trauma database. From this cohort, we selected those individuals who had undergone intravenous CECT scanning within 24 hours after admission and who had an Abbreviated Injury Score more than 3 because of their pelvic injury. Those individuals who required arterial embolization for uncontrolled hemodynamic shock were categorized as having "significant arterial bleeding" attributable to their pelvic injury. Individuals who regained hemodynamic ,stability without embolization were categorized as having "no significant arterial bleeding." Two observers who were blinded to clinical information and the results of angiography reviewed all injury radiographs and computed tomographic scans. The presence or absence of contrast extravasation on intravenous CECT was recorded. Each case was then categorized into a 2 x 2 table depending on the presence of contrast extravasation on CECT and the need for arterial embolization to determine the accuracy of the "contrast extravasation sign." RESULTS: Of the 192 eligible patients, 111 met the inclusion criteria. Eleven patients required an angiogram for ongoing hemodynamic instability. The sensitivity of extravasation on contrast enhanced computed tomography representing a significant arterial bleeding was 80%, and the specificity was 98%. The predictive value of a positive contrast "extravasation sign" was 80%, whereas the predictive value of a negative test was 98%. The likelihood ratio of a positive test was 40.4, and the likelihood ratio of a negative test was 0.204. CONCLUSION: The finding of contrast extravasation on CECT is highly suggestive of significant arterial bleeding that requires early angiographic embolization to restore hemodynamic stability.

Abbreviated Injury Scale↗
PubMed1999

Genetic, morphometric and immunohistochemical markers of latent coeliac disease.

BACKGROUND: It is recognized that coeliac disease may exist in a latent form characterized by HLA-DR3 and increased counts of intra-epithelial lymphocytes (IELs) and gamma/delta T cells in jejunal biopsies. To determine whether subjects with persistent serological markers 4 and 13 years after a population screening survey have the HLA constitution of coeliac disease and/or minor morphometric abnormalities of the small intestine, including raised gamma/delta T-cell counts, as possible indicators of latent coeliac disease. SUBJECTS: Participants with positive serology detected by the Belfast MONICA Project surveys (1983 and 1991) were subdivided into those with persistently positive serology (persistent serology), negative serology at follow-up (transient serology) and those with enteropathy (coeliac disease). Morphometric features were compared with MONICA controls who had negative serology and HLA antigen frequencies were compared with blood donor controls. METHODS: Subjects were followed up in 1994-1996 and were re-tested for IgA antibodies to gliadin, endomysium and reticulin. HLA typing was carried out and IELs and gamma/delta T-cell counts were assessed in jejunal biopsies in subjects who gave consent. RESULTS: Persistent serology mainly concerned antigliadin (AGA) and antireticulin (ARA) antibodies but one patient had positive antiendomysial antibody (EMA) and ARA in 1983, which became negative at follow-up, at which time they were positive for AGA. No significant differences were observed between IELs or gamma/delta T-cell counts when the persistent and transient groups were compared in turn with the MONICA controls. HLA-DR2 was expressed in 11 of 16 in the persistent group compared to 47 of 150 blood donor controls (P = 0.013). HLA-DR3 occurred in 15 of 17 coeliac patients compared to 37 of 150 blood donors (P = 0.00001). CONCLUSIONS: Persistent serological markers following population screening do not appear to indicate latent coeliac disease.

Adult↗
PubMed1998

Effects of a microdose of medetomidine on diazepam-ketamine induced anesthesia in dogs.

OBJECTIVE: To evaluate cardiorespiratory and anesthetic effects of a microdose of medetomidine hydrochloride on diazepam-ketamine (DK) hydrochloride induced anesthesia in dogs. DESIGN: Randomized crossover study. ANIMALS: 6 two-year-old healthy female dogs. PROCEDURE: A study was designed to compare quality of anesthetic induction, recovery, analgesia, muscle relaxation, duration of immobilization, and ease of endotracheal intubation between diazepam-ketamine-medetomidine (DKM) and diazepam-ketamine induced anesthesia in 6 dogs. Diazepam (0.25 mg/kg [0.114 mg/lb] of body weight, i.v.) and ketamine (5 mg/kg [2.27 mg/lb], i.v.) with or without a microdose of medetomidine (5 micrograms/kg, i.v.) were administered to dogs. A baseline ECG was obtained, and baseline measurements of arterial blood gas tensions, arterial pressures, heart and respiratory rates, and minute volume were taken before drug administration. All measurements were repeated again 5, 10, 20, and 30 minutes after drug administration. Endotracheal intubation was attempted 1 minute after drug administration and then again 5, 10, 20, and 30 minutes after drug administration. Analgesia was evaluated by tail clamp and needle prick testing. RESULTS: Medetomidine improved quality of anesthetic induction, ease of endotracheal intubation, and extended duration of analgesia and lateral recumbency in anesthetized dogs. The addition of medetomidine to DK increased blood pressure and decreased heart and respiratory rates and minute volume. Hypoxemia was observed in 1 dog after DKM induced anesthesia. CLINICAL IMPLICATIONS: Administration of a microdose of medetomidine provides a useful adjunct to DK induced anesthesia in dogs. Oxygen insufflation is recommended for a minimum of the first 5 minutes of DKM induced anesthesia.

Adjuvants, Anesthesia↗
PubMed1998

Geriatric psychiatry outreach practices in the province of Ontario: the role of the psychiatrist.

OBJECTIVE: To determine the mode of practice of multidiscliplinary and interdisciplinary teams in the field of geriatric psychiatry in the province of Ontario with specific reference to the role of the psychiatrist on the teams. METHOD: Teams were identified, and a simple questionnaire was developed and submitted to every team at an annual conference. RESULTS: Responses were obtained from 38 out of 47 teams. The composition of the teams is variable as regards size and represented discliplines. Nine teams do not have psychiatrists directly affiliated with them. Eighteen teams, 4 of which are based in teaching hospitals, have fewer than 1 full-time equivalent (FTE) psychiatrist. Among these teams, 4 have fewer than 0.1 FTE psychiatrist and 10 have fewer than 0.5 FTE psychiatrist. Eleven teams include between 1 and 1.5 FTE psychiatrists on their staff. Four teams (10.5%) require that the initial assessment of all patients be undertaken by a psychiatrist. In 18 (47%) of the teams, assessment by a psychiatrist can be infrequent or nonexistent. Discussion of the referral with a psychiatrist occurs in the majority of teams, but in a significant minority (10 [27%]), this occurs quite infrequently or not at all. CONCLUSION: Geriatric psychiatry outreach practices in Ontario involve many different disciplines in the assessment and follow-up of geriatric psychiatry patients, often without the ready availability of psychiatric input. We applaud the expanding roles of different disciplines in this practice. We are concerned, however, at the paucity of psychiatrists working in this field.

Aged↗
PubMed1997

Correlation of peak systolic velocity and angiographic measurement of carotid stenosis revisited.

BACKGROUND AND PURPOSE: Recent observations from the North American Symptomatic Carotid Endarterectomy Trial (NASCET) questioned the reliability of peak systolic velocity (PSV) criteria for grading carotid stenosis. We compared PSV and angiographic measurements at our center together with known physiological relationships to investigate the accuracy of ultrasound. METHODS: Consecutive patients who underwent both color-coded duplex ultrasound and intra-arterial digital subtraction angiography were studied. PSV was determined with angle correction at the site of the tightest internal carotid artery narrowing. Carotid stenosis was measured on angiograms with the North American (N) and common carotid (C) methods. Variables for the stepwise multiple linear regression analysis were selected from an axisymmetrical flow model. RESULTS: Eighty bifurcations were imaged in 40 patients. PSV did not exceed 140 cm/s in normal vessels. In diseased arteries, PSV increased proportionally with increasing stenosis and decreased to 0 cm/s at occlusion. In stepwise selection of polynomial terms, the linear, quadratic, and cubic correlations of .38, .17, and .22 for N and .45, .24, and .03 for C were found to be significant (P < .02). When only stenosed vessels were evaluated, PSV increase was found with greater scatter for the N measurement: r2 = .73 for N and r2 = .85 for C (n = 50; P = .03 for the difference between two correlated correlation coefficients). CONCLUSIONS: At our laboratory PSV consistently correlates well with N and C angiographic measurements, as determined with a simple flow model. The complex nature of these correlations and greater variability of the N measurement should be taken into account when data from different centers are compared.

Angiography, Digital Subtraction↗
PubMed1997

Grading carotid stenosis with ultrasound. An interlaboratory comparison.

BACKGROUND AND PURPOSE: Carotid ultrasound had modest accuracy in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) of carotid endarterectomy in predicting severe carotid stenosis when a 250-cm/s peak systolic velocity (PSV) criterion was applied to different laboratories. We compared the performance of two independent laboratories using similar equipment (ATL-HDI Ultramark 9) but different interpretation criteria. METHODS: Consecutive patients who underwent both color-coded duplex ultrasound and intra-arterial digital subtraction angiography were studied. PSV was determined with angle correction at the site of the tightest arterial narrowing. Carotid stenosis was measured on angiograms using the North American (N) method. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values with 95% confidence intervals were calculated for each laboratory. RESULTS: In 87 patients, 174 bifurcations were imaged. A 250-cm/s criterion was the best single predictor of a > 70% N stenosis at one laboratory (sensitivity 93% [95% confidence interval, 85 to 101], specificity 86% [76 to 96], PPV 75% [62 to 87], and NPV 96% [90 to 102]) but had modest parameters at the other laboratory (50% [34 to 64], 87%, [77 to 97], 60 [44 to 76], and 91 [82 to 100], respectively). However, the diagnostic criteria routinely used in the second laboratory included different velocity values, which when applied decreased specificity by 17% but increased sensitivity by 35% (85% [74 to 96], 70% [56 to 84], 90% [81 to 99], and 77% [64 to 90], respectively). CONCLUSIONS: Despite the use of similar equipment, ultrasound grading of carotid stenosis is operator dependent and relies on different and individually validated criteria. Greater sensitivity of ultrasound screening is achieved by applying diagnostic criteria specific to each laboratory. Multicenter studies should use laboratory-specific criteria and a local validation process.

Angiography, Digital Subtraction↗
PubMed1996

Flow cytometric analysis does not reliably differentiate benign from malignant phaeochromocytoma.

BACKGROUND AND OBJECTIVE: The differentiation of benign from malignant phaeochromocytoma is difficult. We have examined whether the use of flow cytometric determination of nuclear DNA content would be useful as a predictor of malignant behaviour in patients with phaeochromocytoma as some previous studies had suggested that a diploid cytometric DNA pattern indicated benign disease. DESIGN AND PATIENTS: DNA flow cytometry was performed on phaeochromocytoma tissue from 36 patients (19 female, 17 male; mean age at presentation 39.5 years). The results were correlated with clinical outcome after prolonged follow-up. MEASUREMENTS: DNA histograms were constructed following nuclear suspension analysis. RESULTS: Of 26 patients followed up for more than 5 years after initial removal of primary phaeochromocytoma, three have died from malignant recurrence. In these patients a diploid DNA cytometric pattern was observed in two and an aneuploid pattern in one. Twenty-one patients are still alive. DNA cytometry showed a diploid pattern in the one patient who developed recurrent phaeochromocytoma 4 years after removal of a primary tumour. CONCLUSION: In this study, three of nine patients with an apparently benign diploid cytometric pattern subsequently developed recurrent disease. Routine use of DNA flow cytometry did not reliably differentiate benign from malignant phaeochromocytoma. Prolonged clinical and biochemical follow-up is still necessary for all patients with this condition.

Adult↗
PubMed1996

Emergent abdominal sonography as a screening test in a new diagnostic algorithm for blunt trauma.

Although there is an interest in emergent abdominal sonography (EAS), the clinical utilization of EAS in North America is minimal. The purpose of this study was to develop a new diagnostic algorithm for blunt abdominal injury based on a prospective blinded comparison of EAS, diagnostic peritoneal lavage (DPL), and computed tomography (CT). EAS (+ = fluid, - = no fluid) was performed before the DPL or CT, in 400 patients with a mean Injury Severity Score of 26; 293 had a CT and 107 had a DPL. The EASs required 2.6 +/- 1.2 minutes with 82% < or = 3 minutes. The accuracy of EAS for free fluid was 94% with a positive and negative predictive value of 82 and 96%, respectively. Only 1 of 338 patients with EAS- had an acute therapeutic laparotomy. Three patients with EAS- had a delayed laparotomy based on evolving clinical findings. The radiologists interpretation of the EAS video disagreed with the clinician sonographer in only 3% of cases. Based on these results, a diagnostic algorithm was developed using EAS as a screening test with selective use of DPL and CT. Emergent abdominal sonography performed by clinician sonographers is a rapid and accurate test for peritoneal fluid in blunt trauma victims, and the need for laparotomy in patients with a negative EAS is rare. Our study supports the routine use of EAS as a screening test in a diagnostic algorithm for the evaluation of blunt abdominal trauma.

Abdominal Injuries↗
PubMed1996

Hypotension after blunt abdominal trauma: the role of emergent abdominal sonography in surgical triage.

OBJECTIVE: Trauma victims with hypotension require a rapid and reliable localization of bleeding and expedient surgical triage. Our hypothesis is that emergent abdominal sonography (EAS) is a rapid and accurate test of the need for urgent laparotomy in blunt trauma victims with hypotension. METHODS: Among 400 blunt trauma victims entered in a prospective blind study of EAS, a subgroup of 69 (17%) patients had a systolic blood pressure < or = 90 mm Hg during their initial assessment. Although the EAS results [(+) = fluid, (-) = no fluid] were not used in clinical decision making, the potential contribution of EAS to patient care was examined. RESULTS: The mean Injury Severity Score was 32. Twenty-two (32%) patients were EAS (+), of which 19 required an acute laparotomy. No laparotomies were performed in the 47 EAS (-) patients. The EASs required 19 +/- 5 seconds in the EAS (+) group and 154 +/- 13 seconds in the EAS (-) group. Twenty of the 22 positive EASs had free fluid in Morison's pouch. All 13 patients with an ultrasound score > or = 3 had a laparotomy. The primary etiology of hypotension was blood loss in 42 patients, hemoperitoneum in 18, and retroperitoneal hemorrhage in 12. CONCLUSION: EAS is a rapid and accurate indicator of the need for urgent laparotomy in the hypotensive blunt trauma victim. Further, a negative EAS can hasten the search for other causes of hypotension. Diagnostic peritoneal lavage may become obsolete in centers with EAS capabilities.

Abdominal Injuries↗
PubMed1996

A randomised prospective study of outpatient haemodilution for central retinal vein obstruction.

PURPOSE: Central retinal vein obstruction (CRVO) has significant visual morbidity. We prospectively evaluated an outpatient haemodilution (HD) regimen for CRVO. METHODS: We recruited 59 patients with CRVO of less than three months' duration and visual acuity (VA) worse than or equal to 6/9.5. Thirty patients underwent HD (packed cell volume of <0.35, 12 weeks); there were 29 controls and follow-up was for six months. RESULTS: Incidence rates for VA improvement (P = 0.708) and rubeosis iridis (P = 0.619) between the two groups were not different. The incidence rate of VA deterioration was 5.315 times higher with HD (P = 0.035, Cox Proportional analysis). CONCLUSION: This data does not support the previous studies on haemodilution.

Adult↗