Acceleromyograph

Device used to measure muscle response to nerve stimulation

Acceleromyography is a technique used in anesthesiology to monitor the effects of neuromuscular blocking agents during surgery. It involves the use of an acceleromyograph, a device that measures the acceleration of a muscle in response to nerve stimulation. This method is particularly useful for assessing the degree of neuromuscular blockade and ensuring adequate recovery of muscle function postoperatively.

Principle of Operation

Acceleromyography is based on the principle that muscle contraction results in movement, which can be quantified by measuring acceleration. When a peripheral nerve is stimulated, the muscle it innervates contracts, and this contraction can be detected by an accelerometer attached to the muscle or a nearby structure. The accelerometer converts the mechanical movement into an electrical signal, which is then analyzed to determine the strength and duration of the muscle contraction.

Clinical Applications

Acceleromyography is primarily used in the operating room to monitor the effects of neuromuscular blocking agents, which are drugs used to induce muscle relaxation during surgery. By providing real-time feedback on the degree of neuromuscular blockade, acceleromyography helps anesthesiologists adjust drug dosages to achieve the desired level of muscle relaxation while minimizing the risk of residual paralysis after surgery.

Monitoring Neuromuscular Blockade

The most common application of acceleromyography is in monitoring the depth of neuromuscular blockade. This is typically done using the train-of-four (TOF) stimulation pattern, which involves delivering four electrical stimuli in rapid succession to a peripheral nerve. The acceleromyograph measures the muscle response to each stimulus, and the TOF ratio (the amplitude of the fourth response divided by the amplitude of the first response) is used to assess the degree of neuromuscular blockade.

Recovery from Neuromuscular Blockade

Acceleromyography is also used to monitor recovery from neuromuscular blockade. A TOF ratio of 0.9 or greater is generally considered indicative of adequate recovery, meaning the patient is likely to have sufficient muscle strength to maintain airway patency and adequate ventilation without assistance.

Advantages and Limitations

Acceleromyography offers several advantages over other methods of neuromuscular monitoring, such as electromyography and mechanomyography. It is non-invasive, easy to use, and provides quantitative data that can be used to guide clinical decision-making. However, it also has limitations, including potential variability in measurements due to changes in sensor position or patient movement.

Related Pages

• Neuromuscular monitoring
• Anesthesia
• Peripheral nerve stimulation
• Train-of-four

Gallery

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  Acceleromyography monitoring with preload hand adapter
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  TOF watch monitor for acceleromyography