Case 26 by Samantha Lyons and Chris Andersen

[az_toggle_section] [toggle title=”History” id=”tgl-1″]A 68 year old gentleman with a background of moderately severe asthma had an urgent shoulder washout for an infection, 6 weeks post reconstruction.

He had a general anaesthetic and an interscalene brachial plexus nerve block with 0.25% marcaine for post-operative analgesia.

You are asked to see him when he develops respiratory failure in recovery…[/toggle] [toggle title=”Examination” id=”tgl-2″]

Sats 90% on Hudson mask at 6L/m

Tachypnoeic (resp rate 40)

Asymmetrical chest wall movement, less on the right

Good air entry throughout, except at right base

No rhonchi or wheeze

No chest pain or pleurisy

BP 140/80

HR 105 sinus rhythm

What’s your differential diagnosis?

[/toggle] [toggle title=”1st CXR” id=”tgl-3″] [az_lightbox_image_sh image_url=”https://intensivecarenetwork.com/wp-content/uploads/2015/11/Recovery-CXR.jpg” thumb_width=”” title=”” gallery_name=”” class=””]With permission from the patient[/toggle] [toggle title=”CXR at 14h” id=”tgl-4″] [az_lightbox_image_sh image_url=”https://intensivecarenetwork.com/wp-content/uploads/2015/11/12hrs-post-op-CXR.jpg” thumb_width=”” title=”” gallery_name=”” class=””]With permission from the patient[/toggle] [toggle title=”Answer” id=”tgl-5″]Phrenic nerve paralysis from the marcaine local anaesthetic, causing paralysis of the right hemi-diaphram and respiratory failure.

He was treated with non-invasive ventilation and rapidly improved.

12 hours later he had completely normal respiratory function, his CXR had normalised, and he was discharged to the ward.[/toggle] [toggle title=”More Info” id=”tgl-6″]

Interscalene brachial plexus block is a reliable and commonly performed technique for surgery of the arm and shoulder. It anaesthetizes the caudal portion of the cervical plexus (C3, C4) and the superior (C5, C6) and middle (C7) trunks of the brachial plexus.

Like many regional anaesthetic approaches it is often used in the management of patients with cardiorespiratory disease. The required patient position means it is well tolerated by disorientated patients or those with trauma to the upper arm or shoulder. With correct technique, pneumothorax is rare due to the level at which the block is performed¹.

However, it is not without risk. It has been demonstrated that interscalene brachial plexus blockade is associated with a 100% incidence of ipsilateral hemidiaphragmatic paralysis² secondary to phrenic nerve palsy. The phrenic nerve arises chiefly from the C4 root, with variable contributions from C3 and C5. It is formed at the upper lateral border of the anterior scalene muscle and courses between the ventral surface of the anterior scalene muscle and prevertebral fascial layer that covers this muscle. It is therefore separated from the brachial plexus only by a thin fascial layer. Consequently, phrenic nerve palsy can be explained by its proximity to the brachial plexus or the cephalad spread of local anaesthetic to C3-5 nerve roots before their formation of the phrenic nerve.

Phrenic nerve palsy is associated with significant reductions in ventilator function: a 21-34% decrease in forced vital capacity and 17-37% decrease in forced expiratory volume in 1 second (FEV₁)³. Urmey et al.² demonstrated normal to paradoxical motion of the ipsilateral hemidiaphragm using ultrasound in all (n=13) patients following interscalene block. Five of the 13 patients complained of mild dyspnea or altered respiration. Patients selected did not have significant pre-existing respiratory disease. Given ventilation can be compromised by interscalene block, utilization of this technique should be potentially restricted in patients with limited pulmonary reserve such as chronic obstructive pulmonary disease, morbid obesity or the elderly.

Riazi et al.⁴ compared the effect of local anaesthetic (20 vs. 5 mls) on the efficacy and respiratory consequences of ultrasound guided interscalene brachial plexus blocks. They reported that administration of low-volume interscalene block under ultrasound guidance decreases the incidence of hemidiaphragmatic paresis and preserves respiratory function, without compromising analgesic effect. Ultrasound-guided technique facilitates direct visualisation of target nerves, adjacent structures and needle position. Thus, local anaesthetic can be administered accurately and the spread more precisely assessed.

An effective interscalene block can be anaesthetic and later opioid sparing; this is of particular value in more frail patients, particularly those with cardiorespiratory pathology. Therefore, measures to reduce complications such as diaphragmatic dysfunction should be encouraged so that such techniques can remain viable for such patients.

Read about how to do an interscalene block here or watch it here:

[az_lightbox_video_sh image_url=”https://intensivecarenetwork.com/wp-content/uploads/2015/11/interscalene-block.jpg” thumb_width=”” link_url=”https://www.youtube.com/watch?v=Zke6938Y1k4″ title=”” gallery_name=”” class=””]

References

Winnie AP. Interscalene brachial plexus block. Anaesthesia and Analgesia. 1970; 49:455-466.
Urmey WF., Talts KH. & Sharrock NE. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anaesthesia as diagnosed by ultrasonography. Anaesthesia and Analgesia 1991; 72:498-503.
Urmey WF. & MacDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: effects on pulmonary function and chest wall mechanics. Anaesthesia and Analgesia. 1992; 74:352-357.
Riazi S., Carmicheal I., Awad I., Holtby RM. & McCartney CJ. Effect of local anaesthetic volume (20 vs. 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block. British Journal of Anaesthesia. 2008; 101(4): 549-556.

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