Wednesday, 20 January 2010

A Classic Bedside Physical Sign - Asterixis

Dear Bloggers

Above is the classic sign of Flapping Tremor, also termed Asterixis, commonly seen in hepatic encephalopathy and CO2 retention. It is also seen in uraemia. The clues for the cause in this patient were the obvious jaundice and palmar erythema. Smelling the breath also revealed the classic Fetor Hepaticus -- sadly there is no current technological means to purvay this smell across the internet! Abdominal palpation revealed hepatomegaly.

The technique for asterixis is performed by asking the patient to extent their arms so that they are straight at the elbow. The patient is then instructed to extend the wrists and spread the fingers wide. This will allow asterixis to be uncovered.

Pearl: When you see a jaundiced patient ask them to perform the test for asterixis. A positive test suggests encephalopathy e.g. Grade 2 Hepatic Encephalopathy. If the patient has known COPD, e.g. the archetypcal chronic bronchitic 'blue bloater' and a positive asterixis sign, checking a blood gas for rising CO2 levels is justified. Remember that Type 1 respiratory failure patients e.g. emphysematous 'pink puffers' can also develop type 2 respiratory failure on occasion!

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