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Biomedical subjects

J E Davidson

Publications and source records attributed to J E Davidson.

15 recordsLinked to original sources

Complement activation in Henoch-Schönlein purpura.

The pathogenetic mechanism underlying Henoch-Schönlein purpura (HSP) is poorly understood. Complement activation has been thought to have a role, but despite the demonstration of complement components in skin and renal biopsy material, serological evidence of complement activation is not convincing. We have assessed complement activation in 64 children with acute HSP. We used an enzyme-linked immunosorbent assay to measure plasma levels of three multimolecular complement activation protein (CAP) complexes: C1r:C1s:C1-inhibitor, C3bP and C5b-9. We found no significant difference between the levels of CAPs in children with acute HSP and a control group of children. This study does not support a role for complement activation in the pathogenesis of HSP.

Adolescent

The neutrophil oxidative burst in diarrhoea-associated haemolytic uraemic syndrome.

Neutrophil-mediated tissue damage has been implicated in the pathogenesis of diarrhoea-associated haemolytic uraemic syndrome (D+ HUS). This study evaluates priming and activation of the neutrophil oxidative burst in D+ HUS using chemiluminescent techniques. Peripheral blood neutrophils from 11 children with acute D+ HUS were examined. No difference was found in the oxidative burst of neutrophils from patients and controls. Serum elastase levels were measured in 8 patients and found to be significantly elevated. Although elastase results suggest neutrophil activation, chemiluminescence studies do not confirm this in the peripheral blood neutrophil. This does not support a significant role for circulating agents in priming and activating the peripheral blood neutrophil.

Child

Schizophrenia.

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Antipsychotic Agents

Ulnar peripheral nerve stimulation by train-of-four technique in adult nonmedicated patients.

BACKGROUND: Peripheral nerve stimulation is necessary to quantify the level of neuromuscular blockade and prevent prolonged paralysis related to drug accumulation. Some nurses and physicians are hesitant to administer nerve stimulation because of concerns about inflicting pain on the patient. OBJECTIVE: To describe the feeling associated with train-of-four ulnar nerve stimulation, and to quantify discomfort, monitor heart rate response, and define the amount of current necessary to stimulate thumb adduction. METHODS: Healthy, nonmedicated volunteer subjects (N = 39) were asked to describe train-of-four ulnar nerve monitoring at 3 current strengths. Heart rate was monitored throughout the testing procedure. The milliamperes delivered at each current strength and the occurrence of thumb adduction were recorded. RESULTS: Subjects described nerve stimulation generally as an unusual prickly sensation. On a discomfort scale of 1 to 10, the mean discomfort score when stimulated with the current setting at 4 (15.5-23.6 mA) was 3.63. Level 4 stimulation produced thumb adduction in 54% of subjects. No heart rate change occurred in response to nerve stimulation. CONCLUSION: Nerve stimulation by train-of-four method was moderately uncomfortable but not painful. Heart rate response could not be relied on as a measurement of discomfort. Protocols for stimulation should include testing at level 4 and increasing as necessary to cause thumb adduction.

Adult

Neuromuscular blockade: indications, peripheral nerve stimulation, and other concurrent interventions.

Neuromuscular blocking agents (NMBAs) are used in critical illness to reduce metabolic demands and prevent ventilator asynchrony in patients refractory to sedation and anxiolysis. Concurrent interventions for patients receiving neuromuscular blockade include many factors related to prevention, maintenance, and monitoring during immobilization. Prevention interventions include skin care, turning regimes, physical therapy, eye care, and pulmonary toilet to prevent atelectasis, pneumonia, skin breakdown, and corneal ulceration. Maintenance interventions include provision of nutrition, sedation, anxiolysis, and psychosocial support. Monitoring interventions include trending oxygenation parameters and ventilatory care parameters, as well as assessment of the depth of paralysis by assessing clinical evidence of movement, airway pressure waveforms, and peripheral nerve stimulation results. Cost of therapy is influenced by preventing the side-effects of immobility, the choice of NMBA, and concurrent drug therapies, as well as by titration of the NMBA to the lowest drug dose possible to obtain clinical end-points. Clinical end-points are individualized by the prescribing physician and may range from "no movement" to "movement acceptable but no evidence of spontaneous respirations" to "movement acceptable but no ventilator asynchrony." Whenever "no movement"c is identified as the goal, a nerve stimulator is used to identify the depth of paralysis and prevent accidental surplus drug administration, which may result in prolonged paralysis. Methods for using the nerve stimulator and troubleshooting techniques are discussed.

Critical Care

Effect of intermittent pneumatic leg compression on intracranial pressure in brain-injured patients.

OBJECTIVE: To evaluate the effect of intermittent pneumatic leg compression on intracranial pressure and cerebral perfusion pressure in brain-injured patients. DESIGN: Prospective, sequential patient study. SETTING: Surgical/trauma ICU of a community hospital providing regional trauma care. PATIENTS: Twenty-four adult, brain-injured patients (mean Glasgow Coma Scale score = 6) who required hemodynamic and intracranial pressure monitoring. INTERVENTIONS: Placement of intermittent sequential pneumatic leg compression devices for prevention of venous thrombosis. MEASUREMENTS: Mean arterial pressure (MAP), heart rate, central venous pressure, and intracranial pressure were measured at baseline, and at 0, 10, 20, and 30 mins of intermittent pneumatic leg compression. Cerebral perfusion pressure was calculated as the difference between MAP and intracranial pressure. RESULTS: No significant changes in MAP, central venous pressure, or intracranial pressure occurred during the study interval. Calculated cerebral perfusion pressure remained unchanged. A total of 23 of 24 study patients had intracranial pressure controlled by hyperventilation or pharmacologic measures within the normal range at the time of study. CONCLUSION: Intermittent pneumatic leg compression results in no significant changes in intracranial pressure or cerebral perfusion pressure in stable, brain-injured patients who have intracranial pressure controlled by medical means.

Blood Pressure

Measurement of complement activation products in patients with chronic rheumatic diseases.

Measurement of the complement activation products C1s:C1-inh, C3bP and C5b-9 by ELISA in plasma samples from normals, rheumatoid arthritis (RA) and systemic lupus erythematosis (SLE) patients showed significantly elevated levels in the two patient groups (P less than 0.0001 for C1s:C1-inh, C3bP and C5b-9) compared to normals. In seropositive RA patients there were significant correlations between the levels of the three complement activation complexes and IgM-RF, IgG-RF and IgA-RF. However, IgM-RF did not interfere with any of the ELISA systems. Mean levels of C1s:C1-inh, C3bP and C5b-9 were the same in paired plasma and synovial fluids; however, C3bP levels in the paired samples did not correlate with one another by rank. Our conclusions are that: (a) elevated plasma levels of these complement activation products are detectable in rheumatic diseases; (b) plasma levels of these complement activation products are related to Rheumatoid factor (RF) levels in seropositive RA patients; and (c) IgM-RF does not influence these solid-phase ELISA procedures.

Antibodies

Thoracoscopy: nursing implications for optimal patient outcomes.

Many patients who once were considered for open chest procedures now benefit from examination and treatment of pleural disease via thoracoscopy. The thoracoscopist enters the chest cavity through small incisions through the chest wall. Procedures are performed through a video assisted thoracoscope (much like a bronchoscope or endoscope). Wound care, maintenance of the chest drainage system, pain management and vigilant assessment of the cardiorespiratory system following the procedure are integral nursing interventions when caring for these patients.

Adult