Citations
To evaluate the risk of phrenic nerve injury during ultrasound-guided stellate ganglion block (US-SGB) according to sonoanatomy of the phrenic nerve, and determine a safer posture for needle insertion by assessing its relationship with surrounding structure according to positional change.
Twenty-nine healthy volunteers were recruited and underwent ultrasound in two postures, i.e., supine position with the neck extension and head rotation, and lateral decubitus position. The transducer was placed at the anterior tubercle of the C6 level to identify phrenic nerve. The cross-sectional area (CSA), depth from skin, distance between phrenic nerve and anterior tubercle of C6 transverse process, and the angle formed by anterior tubercle, posterior tubercle and phrenic nerve were measured.
The phrenic nerve was clearly identified in the intermuscular fascia layer between the anterior scalene and sternocleidomastoid muscles. The distance between the phrenic nerve and anterior tubercle was 10.33±3.20 mm with the supine position and 9.20±3.31 mm with the lateral decubitus position, respectively. The mean CSA and skin depth of phrenic nerve were not statistically different between the two positions. The angle with the supine position was 48.37°±27.43°, and 58.89°±30.02° with the lateral decubitus position. The difference of angle between the two positions was statistically significant.
Ultrasound is a useful tool for assessing the phrenic nerve and its anatomical relation with other cervical structures. In addition, lateral decubitus position seems to be safer by providing wider angle for needle insertion than the supine position in US-SGB.
Citations
Objective: To confirm the clinical utility of diaphragmatic needle electromyography (EMG) in patients with respiratory dysfunction.
Method: Needle electorode was inserted into the muscle just above the lower costal margin between anterior axillary and medial clavicular lines. Case 1 who showed no response bilaterally in a phrenic NCS and a complete denervation of the diaphragm on needle EMG was unable to be weaned off from the ventilator. Case 2 who showed normal electrodiagnostic findings was successfully weaned off from the ventilator. Case 3 who showed a respiratory insufficiency from organophosphate intoxication had normal electrodiagnostic findings and was able to be successfully weaned off from the ventilator with a psychiatric support.
Result: We ruled out the possibility of lack in central respiratory drive and weaned off patients from the ventilator, based on a normal firing pattern of motor unit potentials.
Conclusion: Phrenic nerve conduction study (NCS) alone is not sufficient to find out the nature of respiratory dysfunction. Needle EMG of the diaphragm can be helpful in determining the pathogenesis, but its utility has been limited due to its potential risks. However we have confirmed that the needle EMG of diaphragm is a safe and easy study to perform and can provide a valuable information in the evaluation and management of respiratory dysfunction.
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