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Severe hypercapnic COPD for shoulder surgery under a block74-year-old man, 62 kg, for elective arthroscopic rotator cuff repair in the beach-chair position

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Know this first

  • Interscalene block often paralyses the phrenic nerve; risky in moderate to severe obstructive disease.
  • The suprascapular nerve gives about 70% of the shoulder joint's supply; blocking it spares the diaphragm.
  • FEV1 under 60% predicted raises the risk of serious pulmonary complications.
  • For a man who retains CO2, aim SpO2 at 88–92%.
  • Stopping smoking for 4–8 weeks is needed to cut pulmonary complications.

The patient

74-year-old man, 62 kg, for elective arthroscopic rotator cuff repair in the beach-chair position. Severe COPD: FEV1 38% predicted, home oxygen 2 L/min, three exacerbations this year; smokes 20 a day. Gets breathless after one flight of stairs. Drugs: tiotropium, salmeterol–fluticasone inhaler, salbutamol as needed. Vitals: BP 146/84, HR 92, SpO2 89% on 2 L/min, RR 20. PaCO2 52 mmHg, PaO2 58 mmHg on oxygen.

The examiner asks

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  1. Consider

    What are your main concerns?

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    • A 74-year-old with severe hypercapnic COPD on home oxygen, for elective shoulder repair, beach-chair. Patient
    • At 74 and hypercapnic, his delirium risk is real; it climbs after 60, so I record his baseline.
    • His FEV1 of 38% is well under 60% predicted, so pulmonary complication risk is high. Disease
    • He retains CO2, so I aim for SpO2 88–92%, not higher.
    • A standard interscalene block would paralyse his hemidiaphragm, which he cannot afford. Surgery
    • In beach-chair, an arm cuff reads higher than the pressure reaching his brain.

  2. Prepare

    How do you assess and optimise him?

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    • First, is he in an exacerbation? Active chest infection means this elective case waits. Disease
    • Arterial gas on his home oxygen as his baseline: PaCO2 52, PaO2 58.
    • Breathless after one flight: well short of the three flights that mark lower risk.
    • Echo for his right ventricle; up to half of COPD patients have RV dysfunction.
    • He should stop smoking now; 4–8 weeks off is what lowers pulmonary complications.
    • He takes every inhaler as usual that morning; salbutamol 2–4 puffs 20–30 minutes beforehand.
    • Incentive spirometry and deep breathing taught before surgery. After surgery

  3. Plan

    What anaesthetic will you give?

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    • No interscalene block: phrenic palsy is a well-known effect, worst in severe obstructive disease. Surgery
    • Low-volume (5–15 mL) anterior suprascapular block: phrenic-sparing, not phrenic-proof.
    • Ropivacaine kept under 3 mg/kg, with lipid emulsion in the room. Stem trigger
    • Light sedation only; over-sedating him drives up his CO2 and pulmonary pressure. Disease
    • If GA is needed: about 6 mL/kg, modest PEEP, slow rate and a long expiratory time. Airway
    • I correct his BP reading to head level and keep cerebral perfusion in the beach-chair. Surgery
    • NIV ready in recovery; COPD is a recognised reason for postoperative NIV. After surgery

  4. Crisis

    Twenty minutes after the block, before incision, he is breathless and anxious. SpO2 84% on 2 L/min, RR 30, BP 150/90, HR 110. What do you do?

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    • Call for help, sit him fully upright and titrate oxygen up to reach 88–92%. (Crisis)
    • Likely phrenic spread even from this block; but I check for LAST and pneumothorax.
    • If LAST: midazolam 1–5 mg for seizures, and lipid 1.5 mL/kg over 2–3 minutes at the first serious sign.
    • Blood gas now and compare with his baseline PaCO2 of 52.
    • Rising CO2 or tiring: NIV and no further sedation.
    • Surgery waits; if NIV fails, I intubate and ventilate slowly with long expiration.

  5. Crisis

    In recovery, after morphine for breakthrough pain, he is drowsy. RR 8, SpO2 96% on 6 L/min by mask. Gas: pH 7.22, PaCO2 82 mmHg. What do you do?

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    • Acute-on-chronic hypercapnia from opioid plus too much oxygen in a CO2 retainer. Crisis
    • Oxygen turned down to keep his SpO2 at 88–92%.
    • Naloxone in 40 mcg IV steps every 2 minutes, at most 200 mcg, until his rate rises.
    • NIV now; postoperative COPD with acidosis is where it helps.
    • Repeat gas soon; if he stays drowsy or acidosis worsens, I intubate.
    • Further analgesia from the block and paracetamol; HDU tonight. After surgery

Fatal mistakes

  • An interscalene block in a man with no respiratory reserve.
  • High-flow oxygen pushing his CO2 higher.
  • Big tidal volumes at a fast rate, trapping gas.
  • Sedating his breathlessness instead of treating it.

Checked against: Miller 10e · Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease, 2025 Report · Barash 9e

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Same topic, another patient

Run these after the main case when you have time. Same skills, a different patient or setting.

Another patient · Pain and regional anaesthesia. Shoulder surgery in severe COPD: phrenic palsy after interscalene block. Same COPD shoulder case: phrenic-sparing block, breathless despite superior trunk

Know this first

  • Interscalene block: phrenic paresis in up to 100%, lasting as long as the block.
  • It suits only patients able to cope with lung function falling by 25%.
  • Phrenic-sparing options: low-volume superior trunk block, anterior suprascapular block.
  • The suprascapular nerve supplies about 70% of the shoulder joint.

The patient

74-year-old man, 108 kg, BMI 36, for elective arthroscopic right rotator cuff repair in the beach-chair position. Severe COPD: FEV1 42% predicted, breathless after 100 metres; on tiotropium and salmeterol-fluticasone. Vitals: BP 142/84, HR 84, SpO2 92% on air, RR 20.

The examiner asks

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  1. Consider

    What are your considerations?

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    • A 74-year-old with severe COPD and obesity, for elective cuff repair in beach-chair. Patient
    • At 74 I record his cognition first; beach-chair surgery often lowers cerebral oxygen saturation.
    • Interscalene block stops his diaphragm on that side in up to 100% of cases, while it lasts. Disease
    • He may not tolerate the 25% drop in lung function that follows.

  2. Prepare

    How do you judge his respiratory reserve before choosing a block?

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    • FEV1 42% and breathless after 100 metres: his reserve is poor. Patient
    • His obesity and severe COPD are exactly where diaphragm palsy turns into real breathlessness. Disease
    • SpO2 92% on air is his baseline; I ask about home oxygen and recent exacerbations. Patient
    • I discuss the trade-off with him: breathlessness from the block against more opioid afterwards.

  3. Plan

    How will you provide anaesthesia and analgesia?

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    • Standard interscalene is unsuitable for him; FEV1 42% can't absorb a 25% fall. Disease
    • A low-volume superior trunk or anterior suprascapular block reduces the phrenic risk but doesn't remove it. Surgery
    • The suprascapular nerve gives about 70% of his shoulder joint's supply.
    • If interscalene is chosen, lower volume: 10–15 mL is usual, 5 mL has been used.
    • Diaphragm ultrasound before and after the block shows whether he has lost movement. Disease
    • GA with a secured airway; arterial line considered for beach-chair pressure. Airway
    • Ephedrine, atropine and glycopyrrolate ready for sudden hypotension and bradycardia sitting up. Surgery

  4. Crisis

    In recovery, despite a low-volume superior trunk block, he is breathless: RR 30, SpO2 85% on 4 L, BP 168/92, HR 110. What do you do?

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    • Hypoxia after his superior trunk block in severe COPD; I call for help and sit him upright. Crisis
    • Phrenic paresis is likely, but I exclude pneumothorax, bronchospasm and high spread.
    • Lung ultrasound: sliding rules out pneumothorax; I check his diaphragm movement on the right.
    • Wheeze means bronchospasm: inhaled salbutamol.
    • Oxygen titrated to 88–92% for his COPD, with a blood gas.
    • CPAP or NIV in HDU until the block wears off; no sedation while he's breathless.
    • A hoarse voice or Horner's is expected spread; I explain it to him. After surgery

Scan · Interscalene brachial plexus

Here is your image. Point to and name each structure, then say why it matters.

Linear high-frequency probe, transverse oblique at cricoid (C6) level, sliding back toward the groove or tracing up from the supraclavicular fossa.

Transverse at the interscalene groove; middle scalene on the left, anterior scalene on the right

Interscalene brachial plexus, labels covered, open the image full size
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Interscalene brachial plexus, labelled, open the image full size

Labels MSM middle scalene muscle · ASM anterior scalene muscle · ellipse: brachial plexus

  • On top is sternocleidomastoid; the plexus lies underneath it.
  • These two muscles are anterior and middle scalene, with the groove between them.
  • These dark round dots in the groove are the upper roots or trunks, my target.
  • The phrenic nerve rides on anterior scalene, so I expect a one-sided diaphragm palsy.
  • Deep and medial sits the vertebral artery, so my needle stays lateral.
  • Medially I may see the carotid and jugular, which I avoid.
  1. Sternocleidomastoid Superficial roof; the plexus sits beneath it
  2. Phrenic nerve on anterior scalene Blocked almost every time at C6: caution in severe lung disease
  3. C5–C7 roots/trunks Target: three or more dark round dots in the groove
  4. Middle scalene In-plane needle crosses it; dorsal scapular and long thoracic nerves inside
  5. Vertebral artery Medial and deep; keep needle lateral and angled slightly caudal
  6. Carotid and internal jugular Sometimes visible medially; vessels to keep clear of

Checked against: Barash 9e · Faust · Miller 10e

Image: Mosaffa F et al., Efficacy Comparison Between Interscalene Block with and Without Superficial Cervical Plexus Block for Anesthesia in Clavicle Surgery (Anesth Pain Med 2024; doi:10.5812/aapm-142051), Figure 2, CC BY 4.0. Changes: Question = panel B (unlabelled), answer = panel A (labelled MSM, ASM, ellipse round the brachial plexus); both cropped to the sonogram, dropping the figure letters and the bottom machine button bar.

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Fatal mistakes

  • A standard-volume interscalene block in severe COPD without discussion.
  • Missing a pneumothorax.
  • Heavy sedation for a breathless patient.
  • Uncontrolled high-flow oxygen with no blood gas.

Checked against: Faust · Miller 10e · Barash 9e · Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease, 2025 Report

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