Search PubMed⌕ Search

Biomedical subjects

J Pickard

Publications and source records attributed to J Pickard.

32 records · Page 2Linked to original sources
PubMed1995

Controversies in thromboembolic disease during pregnancy: a critical review.

OBJECTIVE: To critically appraise the body of literature concerning strategies for the prevention of thromboembolism during pregnancy. DATA SOURCES: We used the Medline data base and reference lists of articles to identify all English-language papers examining thromboembolism during pregnancy. METHODS OF STUDY SELECTION: We identified 156 articles in the obstetric literature and 29 articles in the medical literature that referenced nonpregnant populations. Together, these articles form the primary data base on which most recommendations are based. DATA EXTRACTION AND SYNTHESIS: There are no level 1 trials (large randomized trials with definitive results) in the obstetric literature examining the efficacy of thromboembolism prophylaxis during pregnancy. There are only two level 2 trials (small randomized trials with uncertain results because of moderate to high alpha or beta error) that address prophylactic strategies in pregnant women with histories of thromboembolism or the antiphospholipid antibody syndrome. The remainder of the published trials are observational, some prospective but predominantly retrospective. Many of the recommendations from consensus panels regarding prophylactic strategies in pregnancy were based on level 1 trials in nonpregnant populations. CONCLUSION: Although women with a history of thromboembolic disease are at appreciable risk of recurrence during pregnancy, the exact incidence is unknown and there are no adequate efficacy trials demonstrating that prophylactic regimens are effective. Heparin is the anticoagulant of choice in pregnancy; however, changes in metabolism and clearance make adequate dosing problematic. Expert consensus panels disagree over the optimal management of pregnant women at risk for thromboembolism. Randomized controlled trials during pregnancy are needed if any progress is to be made in combating this lethal disorder.

Anticoagulants↗
PubMed1994

Assessment of cerebral autoregulation with ultrasound and laser Doppler wave forms--an experimental study in anesthetized rabbits.

The aim of the study was to correlate changes in transcranial Doppler blood flow velocity wave form in the basilar artery with cortical red blood cell flux measured with a laser Doppler flowmeter during hemorrhage-induced hypotension in anesthetized and ventilated New Zealand rabbits. Although systolic flow velocity and flux exhibited an autoregulatory threshold at 45 mm Hg, diastolic flow velocity started to fall when mean arterial blood pressure fell below 65 mm Hg. The difference between the mean arterial blood pressure at which diastolic blood flow velocity decreases and the pressure at which mean flux decreases is the difference between systolic and diastolic blood pressure. The increasing divergence between systolic and diastolic flow velocities was reflected in an increase in the amplitude of blood flow velocity pulsations and pulsatility indices. An increase in flux pulsatile wave form was noted as cerebral resistive vessels dilated with hypotension.

Animals↗
PubMed1993

Symmetry of cerebral blood flow and cognitive responses to hypoglycaemia in humans.

A low blood glucose level is associated with impairment of higher cerebral function and an increase in cerebral blood flow. This study examined whether there are differences in the physiological responses to hypoglycaemia between the cerebral hemispheres. Eight healthy men participated in two hyperinsulinaemic glucose clamp studies: after 60 min at 4.5 mmol/l, blood glucose was either lowered to 2.0 mmol/l and "clamped" there for 60 min (hypoglycaemia) or continuously maintained at 4.5 mmol/l (euglycaemia). Cardiac output, middle cerebral artery velocity (transcranial Doppler) and cerebral blood flow (133-xenon inhalation) were measured during the studies. Neuropsychological tests were used to determine whether hypoglycaemia caused differential impairment of hemispheric cognitive function. Hypoglycaemia was associated with symmetrical impairment of cognitive function in both cerebral hemispheres and a rise in cardiac output (from 5.5 [0.2] to 8.7 [0.2] l.min-1, p < 0.0001, mean [standard error]), middle cerebral artery velocity (from 55 [2.6] to 64 [2.8] cm.s-1, p < 0.002), and global cerebral blood flow (from 56 [2.6] to 69 [2.9] ml.100 g-1.min-1, p < 0.005 compared to pre-insulin values). There were no differences in the blood flow response during hypoglycaemia between hemispheres and the increase in blood flow did not correlate with either the change in cardiac output or rise in plasma catecholamine levels. After 120 min of hyperinsulinaemic, euglycaemia, global cerebral blood flow rose significantly above baseline (from 58 [2.4] to 63 [2.2] ml.100 g-1.min-1, p < 0.05). In conclusion, using the techniques described, the physiological and cognitive responses of each cerebral hemisphere to hypoglycaemia were symmetrical.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The hyperaemic response to a transient reduction in cerebral perfusion pressure. A modelling study.

A mathematical model of cerebral blood flow and the cerebrospinal fluid circulation is described which permits the study of phenomena caused by dynamic changes in cerebrovascular autoregulatory or cerebrospinal fluid compensatory reserves. A transient decrease in cerebral perfusion pressure was produced by carotid artery compression. Comparison of the computer simulations with clinical and experimental data, reported elsewhere, suggests that the transient hyperaemic response (THR) is proportional to the strength of the autoregulatory response. The relationships between the magnitude and time course of the THR, and the period and level of reduction in CPP were studied. This model suggests that simple clinical tests based on the examination of THR using transcranial Doppler velocity measurements are of potential value for the non-invasive assessment of the autoregulatory reserve.

Blood Flow Velocity↗
PubMed1990

Reversible cortical blindness as a complication of rheumatoid arthritis of the cervical spine.

A case is presented in which a patient with rheumatoid damage to the cervical spine causing cervical cord and vertebral artery compression sustained transient cortical blindness with a partial left hemiparesis. Magnetic resonance imaging revealed anterior subluxation of middle cervical vertebrae, separation of the odontoid peg with resultant atlantoaxial subluxation, and proliferative pannus formation. The patient was almost symptom-free after transoral decompression and posterior cervical fusion.

Aortography↗
PubMed1990

Cushing's syndrome in pregnancy.

Fertility and childbearing rarely occur in Cushing's syndrome because amenorrhea, oligomenorrhea, infertility, and abortions characterize the disease. Currently, a total of 53 cases of Cushing's syndrome and pregnancy have been reported. When Cushing's syndrome occurs during pregnancy, approximately 56 per cent of the cases are associated with adrenal cortical adenoma or carcinoma. Excluding Cushing's disease, nearly 21 percent of the cases are caused by adrenal carcinoma. The maternal catabolic state of glucocorticoid excess contributes to poor fetal outcome with many of the cases complicated by either fetal wastage or prematurity. However, congenital malformations are not seen more frequently than in normal pregnancy. Pregnancy may or may not influence Cushing's syndrome, but Cushing's syndrome definitely complicates pregnancy.

Adult↗
PubMed1984

A postmortem review of trauma mortalities--a comparative study.

Two hundred two mortalities from blunt trauma from the Coroner's Office of Ontario were reviewed and compared to 102 mortalities seen at the Regional Trauma Unit at Sunnybrook Medical Centre, Toronto, and its 36 referring hospitals (EMSS). Nonpreventable deaths due to head injury were defined and excluded from review. This left 103 mortalities from the Coroner's Office and 52 from the EMSS. The average postmortem I.S.S. of patients dying in the Trauma Unit was 53, compared to 33 in patients treated outside the EMSS. Of EMSS patients 5.8% had an I.S.S. below their LD50, with 53% below their LD50 in the reference group. This postmortem review shows the advantages of an organized system of trauma management.

Accidents, Traffic↗
PubMed1983

Preventable deaths in multiple trauma: review of deaths at Sunnybrook Medical Centre Trauma Unit.

One hundred and two patients, who have died of multiple injuries and on whom an autopsy was performed, have been reviewed. Injury severity was a major factor in the outcome and head injury played a definite role in more than half of the deaths. Missed diagnosis was not a major factor in the deaths. Future improvements will most likely be in the management of hemorrhage in patients with multiple injuries.

Adult↗
PubMed1980

Prostacyclin, indomethacin and the cerebral circulation.

The effect of intracarotid prostacyclin (PGI2) on cerebral blood flow (CBF) was measured by the 133xenon intracarotid injection technique in 8 baboons. Intracarotid prostacyclin increased CBF by 22% at 10(-7) g/kg/min and by 71% at 5 x 10(-6) g/kg/min, accompanied by systemic hypotension and tachycardia. The effects of PGI2 (10(-7) g/kg/min) were not potentiated by transient opening of the blood-brain barrier with the intracarotid hypertonic urea technique. At hypercapnia, the vasoconstrictor effect of indomethacin on the cerebral circulation was reversed by PGI2. These results support our suggestion that a prostaglandin, in particular PGI2, is required for hypercapnia to produce full cerebral vasodilatation. In separate experiments, following craniectomy in 5 cats, PGI2, but not its stable metabolite 6-keto-PGF1 alpha, dilated pial arterioles when locally injected into the mock CSF overlying the arteriole.

Animals↗
PubMed1977

Severe head injuries in three countries.

Methods for assessing early characteristics and late outcome after severe head injury have been devised and applied to 700 cases in three countries (Scotland, Netherlands, and USA). There was a close similarity between the initial features of patients in the three series; in spite of differences on organisation of care and in details of management , the mortality was exactly the same in each country. This data bank of cases (which is still being enlarged) can be used for predicting outcome in new cases, and for setting up trials of management.

Adolescent↗
PubMedDate not supplied

Preventive care in diabetes mellitus. Current practice in urban health-care system.

Early identification and treatment of complications of diabetes mellitus may reduce the severity of the complications. As part of a program to reduce these complications in the Denver Department of Health and Hospitals patient population, our study determined how frequently preventive care, e.g., fundoscopic examinations, referral to an ophthalmologist, foot examinations, and assessment of cardiovascular risk factors, was provided to diabetic patients. With the use of billing records to identify a large sample of diabetic patients, a chart review of 544 patients was conducted. During the study year, the mean +/- SE number of visits to primary-care clinics was 5.7 +/- 0.22, with 86.4% having at least one visit. Most diabetic patients were seen by primary-care physicians; only 9% received care in a specialized diabetes clinic. Despite frequent primary-care visits, most diabetic patients in this county health-care system did not have documentation of care to detect complications of diabetes mellitus, and referral services for detection and treatment of these complications were infrequently used. Moreover, among patients seen on greater than or equal to 10 occasions in a primary-care setting, preventive care was not provided to 30% of the patients. Preventive care does not appear to be a regular part of a primary-care visit for most of the diabetic patients in this study.

Colorado↗