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Biomedical subjects

M C Atkinson

Publications and source records attributed to M C Atkinson.

8 recordsLinked to original sources
PubMed2002

The use of N-acetylcysteine in intensive care.

OBJECTIVE: To review the actions and clinical use of serum N-acetylcysteine in the critically ill patient. DATA SOURCES: A review of articles published on the mechanisms of action and clinical use of N-acetylcysteine. SUMMARY OF REVIEW: N-acetylcysteine (NAC) is an amino acid with a MW of 163.2. It acts as an antioxidant, both directly as a glutathione substitute and indirectly as a precursor for glutathione. It also causes vasodilation by increasing cyclic guanosine monophosphate levels, inhibits platelet aggregation, acts as a sulphydryl donor to regenerate endothelial-derived relaxing factor and reduces IL-8 and TNF-alpha production. While there is evidence for its effectiveness as an antidote to paracetamol poisoning, its use in other disorders has only experimental or anecdotal support. For example, in hepatic failure, there are few studies in man showing improved outcome following NAC therapy. There is also conflicting evidence for the use of NAC in sepsis or ARDS and while there is some evidence to suggest that NAC may be of benefit in acute myocardial infarction, the patient numbers are small. It may also be of use in ameliorating nitrate tolerance. It is also possible that NAC may confer benefit in reducing the risks of radiographic contrast nephropathy, although the study suggesting this was probably insufficiently powered to review all patient subsets (e.g. diabetics). N-acetylcysteine would also appear to enhance T cell function in HIV infected patients. However, the use of NAC for immunomodulation in HIV patients has not yet undergone prospective randomised controlled trials and therefore cannot be recommended as routine therapy in HIV infected, or other immune deficient, patients. There is currently insufficient evidence to propose NAC for the treatment of carbon monoxide poisoning. Whilst there is experimental evidence for a variety of novel roles for NAC, further clinical studies are required before it can be recommended for the routine management of any disorders other than that of paracetamol poisoning. CONCLUSIONS: N-acetylcysteine has antioxidant properties that may be useful in many clinical conditions. Currently, however, it can only be recommended as therapy for paracetamol poisoning, in all other disorders it is still under evaluation.

Journal Article↗
PubMed2000

Exposure in difficult total knee arthroplasty using coronal tibial tubercle osteotomy.

Exposure in a total knee arthroplasty can be challenging regardless of whether it is a difficult primary or a revision. Various techniques both proximal and distal to the patella have been described and implemented to gain exposure and improve knee flexion. When patella eversion is not possible due to previous surgery or severe preoperative knee flexion contracture, a coronal tibial tubercle osteotomy may be utilized. We present successful results utilizing the coronal tibial tubercle osteotomy procedure. The technique involved in this series is based on that described by Whiteside. It involves the development of a long lateral musculoperiosteal flap incorporating the tibial tubercle and anterior tibia, and leaving the proximal tibial cortex intact. This is extended along the tibia distally for 10 cm. It finishes by gradually osteotomising the anterior surface of the tibial crest. The tubercle is reattached with wires at the end of the procedure. This technique minimizes complications that have been associated with the tibial tubercle osteotomy. The 10 knees in 9 patients, who had total knee arthroplasty with a coronal tibial tubercle osteotomy, were reviewed pre and postoperatively. All knees were assessed using the Hospital for Special Surgery knee score (HSS). The scores averaged 43.6 preoperatively (range, 29 57) and 79.2 postoperatively (range, 67 90), and the mean range of motion was 59.5 degrees preoperatively and 78.0 degrees postoperatively. There were no cases of extension lag. Fixed flexion deformity was present in 3 cases postoperatively. Average time to union at the proximal and distal ends of the osteotomy was 8 and 24 weeks respectively. There was no evidence of nonunion and no other significant complications occurred.

Journal Article↗
PubMed2000

Acute venous thromboembolism.

OBJECTIVE: To review the recent advances in management of acute venous thromboembolism. DATA SOURCES: Articles and published reviews on venous thromboembolism, pulmonary embolism and deep vein thrombosis. SUMMARY OF REVIEW: Acute venous thromboembolism describes a group of disorders that include venous thrombosis (usually deep vein thrombosis) and pulmonary thromboembolism. Ultrasound supplemented by Doppler flow detection imaging has become the investigation of choice in the diagnosis of deep vein thrombosis and spiral volumetric computed tomography or ventilation perfusion scan (if the patient is haemodynamically stable) or bedside echocardiography (if the patient is hypotensive) are often the initial investigations in a patient who has a suspected pulmonary thromboembolism. Magnetic resonance venography has only recently been evaluated and may prove in future to be a valuable diagnostic test for both deep vein thrombosis and pulmonary thromboembolism. Treatment requires immediate anticoagulation using either subcutaneous low molecular weight heparin (e.g. enoxaparin 1 mg/kg 12-hourly or dalteparin 100 IU anti Xa/kg twice daily) or intravenous unfractionated heparin (80 U/kg as a bolus then 18 U/kg/hr and adjusted to keep the APTT 1.5-2x the control value). Oral anticoagulation using warfarin is started simultaneously with heparin. Fibrinolytic therapy is considered in all patients with pulmonary thromboembolism in whom there are no contraindications, as the improvement in right ventricular function is greater and the pulmonary artery perfusion defect is less compared with patients treated by anticoagulation alone. Fibrinolytic therapy is usually only considered in patients with deep vein thrombosis if severe limb oedema is present. While streptokinase, urokinase and alteplase have been recommended, alteplase (100 mg over two hours with heparinisation) may be the treatment of choice as alteplase has a shorter half life, has a more rapid effect and may be more effective in lysing older clots, when compared with streptokinase or urokinase. Reteplase (10 U over 2 minutes followed by 10 U 30 minutes later) may be as effective as alteplase. CONCLUSIONS: Acute venous thromboembolism is a disorder that carries a high morbidity and mortality. Anticoagulation with or without fibrinolysis is the treatment of choice.

Journal Article↗
PubMed2000

The efficacy of cardiopulmonary resuscitation in the prone position.

OBJECTIVE: To ascertain whether cardiopulmonary resuscitation (CPR) is effective when performed on a mannequin in the prone position. METHODS: Thirty six registered nurses each performed 100 consecutive chest compressions on a Laerdal Resusci-Annie mannequin immediately after an annual update of CPR technique from an Advanced Life Support (ALS) instructor. Compressions were performed on a mannequin turned to the prone position, on a standard examination couch. A gel.filled pad was placed between the sternum and couch. Nurses were instructed once to perform compressions in the midline, two.thirds the way up the torso 'between imaginary scapulae'. Efficacy of compressions was measured using an integral 'skillmeter' in the mannequin. RESULTS: Of 3600 chest compressions performed, 3376 were assessed by the skillmeter. 1168 (34.6%) compressions were 4.5 cm in depth, 1370 (40.6%) were 2.4 cm in depth, and 868 (24.6%) were less than 2 cm. Sixty one percent of nurses were able to perform adequate CPR at some stage through the cycle. Forty one percent managed to perform adequate CPR throughout the cycle. CONCLUSIONS: Efficient CPR can be performed on a mannequin in the prone position, although additional instruction in technique is required. This may be applicable to patients turned to the prone position.

Journal Article↗
PubMed1999

Extent and practicalities of filter use in anaesthetic breathing circuits and attitudes towards their use: a postal survey of UK hospitals.

A postal survey of 120 UK hospitals was conducted to assess the current use of filters in anaesthetic breathing systems and consultant anaesthetists' opinion of their value; 76% of the questionnaires were returned complete. The survey showed that 77.2% of anaesthetic departments use a new filter for every case, a variety of different filter types being used. A connector distal to the filter was used in 78.3% of patients, providing a possible route for cross infection. Anaesthetists rated the prevention of bacterial infection and gross contamination as being higher priorities than the prevention of viral infection. Of those surveyed, 66.3% believed filters were worthwhile whereas only 35.9% thought they were cost effective. Only 34.8% of anaesthetists believed that the supposed extra efficiency of pleated hydrophobic membrane filters over electrostatic filters merited their extra cost.

Adult↗