Anaesthesia and intensive care
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Anaesth Intensive Care · Aug 1996
Comparative StudyAxillary brachial plexus block in two hundred consecutive patients.
Two hundred consecutive, minimally-sedated patients presenting for upper limb surgery were audited prospectively to determine the overall clinical success rate, extent of cutaneous neural blockade, reliability and complication rate of each indicator of axillary sheath entry, and degree of patient satisfaction. The axillary sheath was identified, using a 22 gauge, short-bevelled needle, by one of four indicators, whichever was elicited first (paraesthesia, arterial or venous puncture, or tethering by the axillary sheath). Alkalinized mepivacaine 1.2%, 50 ml then was injected. ⋯ Complete anaesthesia distal to the elbow was achieved in 85% of patients. Complications were common, but generally mild and transient: mild acute local anaesthetic toxicity, 3.5%; axillary tenderness and bruising, 12%; and dysaesthesias, 12.5%. Despite this, patient satisfaction was high (97%).
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Anaesth Intensive Care · Aug 1996
Comparative StudyBrain and blood concentrations of propofol after rapid intravenous injection in sheep, and their relationships to cerebral effects.
The time-course of propofol concentrations in the blood and brain following rapid administration of three doses were examined using a sheep preparation and regional pharmacokinetic techniques. These were compared to the time-course of cerebral effects of propofol reported previously. ⋯ There was evidence that the effect of propofol on cerebral blood flow altered its own rate of elution from the brain. Hysteresis between arterial propofol concentrations and cerebral effects following rapid i.v. administration therefore appears to have a pharmacokinetic basis, and conventional compartmental pharmacokinetic analysis using blood concentrations alone may fail to accurately predict the time-course of both brain propofol concentrations and depth of anaesthesia.
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Anaesth Intensive Care · Aug 1996
Continuous renal replacement therapy in critically ill patients: monitoring circuit function.
There is currently no universally accepted method to monitor circuit function or guidelines for circuit replacement during continuous renal replacement therapies (CRRT). The objectives of this study were to diagnose the causes of circuit failure, identify factors responsible for circuit clotting and determine a predictive monitor of circuit function. The CRRT technique used in this study was continuous venovenous haemodialysis (CVVHD). ⋯ In any circuit an increase of 26 mmHg or more in the transfilter pressure gradient accurately predicted circuit failure due to clotting and imminent cessation of function. Increases in platelet count, haematocrit, and low circuit flows are important determinants of haemofilter life. The measurement of transfilter pressure gradient across the haemofilter is an accurate bedside monitor of circuit function.