Preoperative Assessment: Respiratory Comorbidities

Obstructive Lung Disease

Asthma

Preoperative:

• Continue bronchodilators on the day of surgery.
• Provide salbutamol prior to anesthesia if patient has active symptoms (e.g. dyspnea/wheeze).

Intraoperative:

• Consider using local / regional anesthesia (e.g. spinal, nerve block) when appropriate.
• If general anesthesia is required, preferentially use less invasive airway manipulations (laryngeal mask airway or mask anesthesia) over endotracheal intubation when appropriate.
• Avoid medications that may release histamine and trigger bronchospasm (e.g. morphine, atracurium, rapid injection of vancomycin).
• Preferentially use agents that promote bronchodilation (propofol, ketamine, sevoflurane, intravenous lidocaine).
• If airway instrumentation is required, it should be performed at deep levels of anesthesia to decrease airway reflexes.
• During mechanical ventilation, set ventilator parameters to allow enough expiration time.
• Treatment options for acute bronchospasm: short-acting inhaled β2 agonists and anticholinergics, glucocorticoids, inhalational anesthetics, ketamine, magnesium, supportive therapy with oxygen and mechanical ventilation.

Postoperative:

• Consider extubation in deep planes of anesthesia (“deep extubation”).

COPD

Preoperative:

• Optimize control and continue puffers.
• Smoking cessation.
• Delay OR for 6 wks after acute respiratory infection.

Intraoperative:

• Consider using local / regional anesthesia (e.g. spinal, nerve block) when appropriate.
• If positive-pressure ventilation is required, be aware of expiratory airflow limitation and risks of breath stacking/dynamic hyperinflation and bullae rupture/pneumothorax.
• Opt for a lung-protective ventilation strategy (6ml/kg) with permissive hypercapnia and allow sufficient expiratory time (avoid high tidal volume, increase expiratory time).
• Avoid targeting lower than baseline PaCO2 in chronic CO2 retainers.
• Treat bronchospasm as previously described (see Asthma section).
• Titrate short or intermediate acting neuromuscular blockers judiciously, ensure complete reversal of neuromuscular blockade at the end of surgery.

Postoperative:

• Carefully titrate supplemental O2 to reach baseline oxygen saturation.
• Optimize pain control while minimizing opioids and sedatives (favour acetaminophen, non-steroidal anti-inflammatories, epidural analgesia, nerve blocks).
• Consider higher levels of postoperative monitoring (intensive care or step-down units, serial arterial blood gas analysis).

Perioperative Management of Obstructive Sleep Apnea (OSA)

See Figure 2 for STOP BANG Score for OSA screening.

Preoperative

• Review sleep study or screen patient for OSA.
• Screen and investigate for OSA-related comorbidities and adequacy of treatment.
• Evaluate and plan airway management options.
• Consider delaying elective surgery for evaluation and initiation of treatment, especially if evidence of obesity hypoventilation syndrome or pulmonary hypertension.
• Determine safety of outpatient surgery.

Intraoperative

• Consider using local / regional anesthesia (e.g. spinal, nerve block) when appropriate.
• During moderate or deeper sedation, maintain high index of suspicion for airway obstruction and use continuous capnography monitoring.
• Minimize use of respiratory depressants: favour shorter-acting anesthetic agents and opioids, ensure complete reversal of neuromuscular blockade at the end of surgery.
• Extubate awake, in head-up position.

Intraoperative

• Carefully monitor in the PACU for adverse respiratory events (desaturations, bradypnea, apnea) and pain-sedation mismatch that may warrant prolonged monitoring.
• Resume CPAP therapy during all moments of sleep, including in the PACU.
• Consider initiating CPAP therapy in patients not previously receiving it.
• Titrate supplemental oxygen to avoid hypoxemia.
• Optimize pain control while minimizing opioids and sedatives (favour acetaminophen, non-steroidal anti-inflammatories, epidural analgesia, nerve blocks).
• Assess adequacy of discharge to unmonitored setting, taking into account underlying risk and adverse respiratory events in PACU.
• Instruct discharged patients to rigorously use CPAP during all periods of sleep until no longer taking opioids.

Figure 2 – STOP BANG Score

For the general population, OSA risk:

• Low: Yes to 0 - 2 questions
• Intermediate: Yes to 3 - 4 questions
• High: Yes to 5 - 8 questions
• or Yes to 2 or more of the 4 STOP questions + male gender
• or Yes to 2 or more of the 4 STOP questions + BMI > 35kg/m²
• or Yes to 2 or more of the 4 STOP questions + neck circumference 17 inches / 43 in males or 16 inches / 41 cm in females

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