COPD and reactive airway disease

Why examiners ask this

Obstructive lung disease appears in most stems as a comorbidity, and it lets the examiner test the full perioperative arc: is the patient optimized, what anesthetic minimizes airway reactivity, how do I ventilate a lung that cannot empty, and how do I get the tube out safely. It stresses judgment about delay and application of knowledge about dynamic hyperinflation.

The 60-second answer

Decision points and the "why"

• Optimize or proceed — I postpone elective surgery for an exacerbation and treat with bronchodilators, prednisone 40 mg daily for 5 days, and antibiotics if sputum is purulent;² urgent surgery proceeds with aggressive bronchodilation. A patient wheezing on the day is at the highest risk of intraoperative bronchospasm.
• Steroids — for poorly controlled or newly diagnosed reversible obstruction, oral methylprednisolone 40 mg daily for 5 days before surgery reduces post-intubation wheeze;³ a short course has not been shown to raise wound infection.
• Airway choice — an endotracheal tube is the strongest trigger for bronchospasm, so I use a supraglottic airway or regional technique when the surgery allows.
• Regional caveat — an interscalene block paralyzes the ipsilateral diaphragm and a high thoracic block weakens accessory muscles; in a patient with an FEV1 below about 1 L, I choose a diaphragm-sparing approach.
• Ventilation strategy — tidal volume 6–8 mL/kg predicted body weight, rate 8–10, I:E 1:3 to 1:4, applied PEEP below the intrinsic level; I watch the expiratory flow curve return to zero before the next breath, because air trapping causes barotrauma and hypotension.
• CO2 retainers — I target an SpO2 of 88–92%² and a PaCO2 at the patient's baseline, because normalizing a chronic retainer's CO2 causes post-extubation hypoventilation from alkalosis.
• Postoperative plan — I sit the patient up, give multimodal and regional analgesia so the patient can cough without opioid depression, restart home inhalers in recovery, and arrange incentive spirometry, because pulmonary complications in these patients come from atelectasis, retained secretions and hypoventilation.
• Drugs — sevoflurane and ketamine bronchodilate,³ and sevoflurane is non-irritant; desflurane irritates the airway; I avoid histamine releasers such as morphine and atracurium, and I reverse with sugammadex to avoid muscarinic airway effects of neostigmine.

The complication they will inject

Twenty minutes into the case the blood pressure falls to 70/40, the peak pressure is rising and the expiratory flow never returns to baseline. This is dynamic hyperinflation: gas trapping raises intrathoracic pressure and reduces venous return. I tell the surgeon, disconnect the circuit for 20–30 seconds and watch the pressure recover, which confirms the diagnosis. I then reduce the rate and tidal volume, lengthen expiration, give a bronchodilator, and support pressure with a vasopressor. If the pressure does not recover with disconnection, or breath sounds are unequal, I look for a pneumothorax, because a bulla may have ruptured.

Pitfalls that cost points

• Normalizing the CO2 in a chronic retainer.
• Ventilating at a normal rate and I:E ratio and missing auto-PEEP.
• Choosing desflurane for a reactive airway.
• Proceeding with an elective case during an exacerbation.
• Forgetting that positive pressure can turn a bulla into a tension pneumothorax.

Rapid-why

Q: Why are FEV1 and FEV1/FVC the key numbers? A: A post-bronchodilator FEV1/FVC below 0.70 defines obstruction, and FEV1 percent predicted grades severity from GOLD 1 (≥80%) to GOLD 4 (<30%) and predicts postoperative pulmonary risk.⁴

Q: Why does ketamine help? A: It releases catecholamines and relaxes bronchial smooth muscle, so it is a good induction agent in active wheeze.

Q: How long after a respiratory infection should a reactive airway patient wait? A: At least 2–4 weeks after symptoms resolve, and ideally longer, because airway hyperreactivity can persist for 6 weeks or more.¹

Q: Why measure an arterial gas preoperatively? A: It sets the baseline CO2 and bicarbonate, which tell me the target for ventilation and extubation.

Numbers to know

Links

• Intraoperative bronchospasm, Preoperative pulmonary evaluation and lung resection criteria (coming), Smoking and the timing of cessation (coming), Postoperative mechanical ventilation and weaning, Ventilator modes, PEEP and IMV vs. pressure control
• Atlas: Monitor atlas: perioperative respiratory events
• GOLD Global Strategy for COPD; GINA Global Strategy for Asthma Management