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Biomedical subjects

S Davidson

Publications and source records attributed to S Davidson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Spectral analysis of heart rate fluctuations and optimum thermal management for low birth weight infants.

Spectral analysis of heart rate variability is studied in 10 healthy growing premature infants to investigate the changes in autonomic balance achieved as a function of changes in skin temperature. Heart rate is obtained from ECG recordings and the power spectrum of beat-to-beat heart rate fluctuations is computed. The infants maintain mean rectal temperature within 36.3-37.2 degrees C, while skin temperature changes. The respiratory rate does not change at the different servocontrol set points. Heart rate is found to increase slightly, but consistently. The low-frequency band (0.02-0.2 Hz), reflecting the interplay of the sympathetic and parasympathetic tone and known to be maximum at the thermoneutral zone, is maximum at 35.5 and 36 degrees C and decreases gradually to a lower level at a servocontrol temperature of 36.5-37 degrees C. The high-frequency band (0.2-2.0 Hz), coinciding with the respiratory peak and reflecting parasympathetic activity, is significantly elevated at 36 degrees C (p < 0.01). The minimum low: high ratio, indicating the minimum sympathetic-parasympathetic balance and possibly reflecting the most comfortable conditions, occurs at 36 degrees C, although the differences are not statistically significant. Servocontrol skin temperature may thus be adapted, and possibly selected at 36 degrees C for growing premature infants in an attempt to achieve thermal comfort and more balanced autonomic activity.

Electrocardiography↗
PubMed1997

Management of the patient with disruptive vocalization.

Disruptive vocalization (DV) is a common problem in the management of cognitively and physically impaired older people. This article reports the results of a consensus meeting convened to provide guidelines for clinicians and recommendations for researchers in this difficult and little-studied behavioral problem. DV arises largely in people with cognitive impairment and generally reflects an underlying need or discomfort. A variety of factors can precipitate and aggravate DV; the key to management is appropriate identification of all possible factors and development of an individualized treatment plan.

Aged↗
PubMed1996

Etiology and characteristics of congestive heart failure in blacks.

In this study of 301 black patients with congestive heart failure (CHF), systemic hypertension is the most common cause of CHF and is the primary etiology of CHF in 61%. Left ventricular hypertrophy is highly prevalent and is seen in 63% of the patients who had an echocardiogram.

Aged↗
PubMed1996

Psychological distress among caregivers to heart transplant recipients.

To test the hypothesis that family caregivers to heart transplant recipients may experience higher than average levels of distress during the period post-transplant and explore the correlates of distress, 83 caregivers were interviewed 3 times during the first year post-transplant and evaluated on predisposing and psychosocial characteristics. Mean distress was significantly elevated above community norms at initial assessment but subsided as the year progressed. Multiple regression analyses showed that: (a) employment status and caregivers' physical health were strong predictors of post-transplant distress while psychiatric history was not; (b) the burden of caregiving was associated with increased distress early post-transplant but not in later months; and (c) intrapersonal and social support resources early post-transplant were associated with distress both short-term and long-term. Interventions targeted at these environmental and personal factors may be important for minimizing negative effects of the transplant experience on family caregivers.

Adolescent↗
PubMed1996

The incidence and cause of coagulopathies in an intensive care population.

We studied 235 patients admitted to an adult intensive care unit in order to determine the incidence and cause of coagulation disturbances. Clinical coagulopathy, defined as bleeding unexplained by local or surgical factors, was identified in 13.6% of patients. Laboratory evidence of coagulopathy was more common: a prothrombin time (PT) ratio > or = 1.5 was found in 66% of patients and a platelet count <100 x 10(9)/l in 38% of patients. Both factors were predictive of excessive bleeding and poor outcome. In a retrospective analysis of plasmas from 45 of the above patients who had PT ratios > or = 1.5 the most common cause was vitamin K deficiency (20%).

Blood Coagulation Disorders↗
PubMed1996

Association of HLA types A1-B8-DR3 and B27 with rapid and slow progression of HIV disease.

We examined how HLA types A1-B8-DR3 and B27 were related to progression of clinical disease and rate of loss of CD4 lymphocytes in the Edinburgh City Hospital cohort of HIV-positive patients, mainly injection drug users. Patients (n = 692) were prospectively followed from 1985 through March 1994. Accurately estimated seroconversion times were determined retrospectively for a subgroup of 313 (45%). Of 262 patients (39%) who were fully or partially HLA typed, 155 (50%) had known seroconversions. Of 34 patients typed positive for A1-B8-DR3, 29 progressed to CDC stage IV, 22 to AIDS and 20 died. Twelve patients were typed positive for B27; six of these progressed to CDC stage IV, one to AIDS and none died. In a proportional hazards analysis of the 313 patients with known seroconversions, A1-B8-DR3 was significantly associated with covariate-adjusted relative risks of 3.7 (95% CI 1.9-7.2), 3.1 (1.6-6.0) and 1.9 (1.1-3.2) for progression from seroconversion to death, AIDS and CDC stage IV, respectively. Events for B27 were too rare to include B27 in analyses to death and AIDS, but B27 was significantly associated with slower progression to CDC stage IV (0.3, CI 0.1-0.9). Random effects growth curve models were used to estimate individual rates of loss of square root CD4 count and loss of CD4 percentage, for 603 and 617 patients, respectively. A1-B8-DR3 was associated with rapid loss of both markers (p = 0.02 and p = 0.01, respectively); B27 was associated with slow loss of both markers (p = 0.04 and p < 0.005).

Acquired Immunodeficiency Syndrome↗
PubMed1996

Intramuscular NSAIDS reduce post-operative pain after minor outpatient anaesthesia.

Two hundred healthy patients scheduled for elective minor gynaecological surgery under general anaesthesia were randomly allocated to one of four groups who received either diclofenac 75 mg intramuscularly (i.m.), ketorolac 30 mg i.m., diclofenac 50 mg orally, or 2 mL NaCl i.m. The drugs were administered 10-20 min prior to a standard anaesthetic. All surgery was uneventful. The patients were discharged after a mean of 110 +/- 30 min with no differences between the groups. Complaints about pain and need for post-operative analgesics were significantly less frequent in the two groups of patients receiving an intramuscular non-steroidal anti-inflammatory drug (NSAID), as compared to placebo. The patients who received 50 mg diclofenac orally, administered shortly before the procedure, had the same pain course as the placebo patients.

Administration, Oral↗
PubMed1996

Immunogenetic factors in HPV-associated cervical cancer: influence on disease progression.

No HLA allele or specificity was significantly different in frequency between a group of 150 cervical cancer patients from north-west England and controls (corrected P values). HLA-DRB1*1501/DQB1*0602 was non-significantly increased, particularly among patients with HPV16-positive tumours. HLA-B7-positive patients had a significantly poorer clinical outcome than HLA-B7-negative patients. A significant component of the genotypic effect is down-regulation of HLA-B7 expression by the tumour cells.

Adult↗
PubMed1996

Failure of early postnatal dexamethasone to prevent chronic lung disease in infants with respiratory distress syndrome.

OBJECTIVE: To study the effect of early postnatal dexamethasone (days 1-3) on the incidence and severity of chronic lung disease in preterm infants with respiratory distress syndrome. METHODS: A multicentre, randomised, placebo controlled, blinded study was carried out in 18 neonatal intensive care units in Israel. The primary outcome measure was survival to discharge without requirement for supplemental oxygen therapy beyond 28 days of life. The secondary outcome measures were requirement for mechanical ventilation at 3 and 7 days, duration of ventilation or oxygen therapy, need for subsequent steroids for established chronic lung disease and incidence of major morbidities. RESULTS: The study consisted of 248 infants (dexamethasone n = 132; placebo n = 116). No differences were found in the outcome variables except for a reduction in requirement for mechanical ventilation at age 3 days in treated infants (dexamethasone 44%, placebo 67%; P = 0.001). Gastrointestinal haemorrhage, hypertension, and hyperglycaemia were more common in treated infants, but no life threatening complications, such as gastrointestinal perforation, were encountered. CONCLUSIONS: These data do no support the routine use of early postnatal steroids, but may justify further study in a selected, high risk group of infants.

Birth Weight↗