Quantitative electromyographic recording at adductor pollicis muscle and stimulation of the ulnar nerve
English: Electromyography is a form of quantitative neuromuscular function monitoring. Electromyography can be used to monitor the effects of and recovery from muscle relaxants when used as part of general anaesthesia. In this photograph the brown and white electrodes stimulate the ulnar nerve. The brown negative electrode is always placed distally on the nerve. The green electrode is placed over the muscle the compound evoked muscle action potential is to be recorded from. https://www.flickr.com/photos/29056374@N04/6102498133 Stimulating Electrodes: White positive Brown Negative Recording electrodes: Black Earth Green Recording EMG electrode Red Neutral EMG electrode EMG electrodes: Protocol for PORC study abductor digiti minimi Stimulation Electrodes: Type: Red Dot ™ Ag/AgCl paediatric micropore™ backed electrodes (3m™) Skin Preparation. Clean, dry, degreased and abraded. Properly prepared skin is essential to provide sufficient current density to obtain supramaximal stimulation. The skin is prepared to remove excess hair, light abrasion to remove some of the stratum corneum and cleaning with alcohol to remove oils will reduce the skin resistance to obtain supramaximal stimulation with the surface electrodes. Types of Electrodes: The stimulating area of the Ag/AgCl conducting electrodes is important and the contact area of the stimulating electrode should be 7-11 mm in diameter. Distance between electrodes The distance between the centres of the stimulating electrodes should be 3 to 6 centimetres. Polarity of electrodes: The negative electrode should be placed distally: Duration of stimulus Stimulus should be a square wave and duration should be 200 microseconds and should be provided as a supramaximal stimulus. Skin Temperature and Core temperature: Changes in temperature at the neuromuscular monitoring site may affect the response to nerve stimulation. Central temperature should be > 35 degrees Celsius and skin temperature > 32 degrees Celsius. Placement of the Stimulating electrodes over the ulnar nerve. Electrodes ( Red Dot ™ Ag/AgCl paediatric micropore™ backed electrodes (3m™) will be attached to the volar (Palmar) side of the distal forearm over the ulnar nerve with the negative (stimulating) BROWN electrode positioned on the lateral side of the flexor carpi ulnaris tendon one to two centimetres proximal to the proximal wrist skin crease and the other positive WHITE electrode placed slightly offset (to ensure span over the ulnar nerve) 3 cm proximal. The ulnar artery runs with the ulnar nerve and can be palpated to confirm the correct position of the placement of the negative stimulating electrode. RNMB is defined as a TOFR <0.9 on 2 readings (that vary by less than 10%) taken 15 seconds apart. The BLACK neutral electrode should be applied in the midline of the proximal wrist crease. RECORDING ELECTRODES The Abductor Digiti Minimi (ADM) recording electrodes: Green – recording electrode is placed over the main muscle bulk of the ADM on the medial (ulnar) aspect of the hand. Red – Neutral electrode is placed over the middle or intermediate phalynx joint of the fifth finger on the medial or volar aspect. A supra-maximal stimulus is applied and an acceptable waveform has a smooth, two phase profile with a well defined initial upward deflection.