2023.1 Day 2 VIVA 8

Airway Management

A 37 year old woman is booked for a diagnostic laparoscopy and dye studies today for investigation of infertility. She has a weight of 95kg, BMI of 35, but otherwise no significant medical history or known allergies. She has not been seen in the pre-anaesthetic clinic.

How would you assess this patient’s airway when planning your anaesthetic?

Obesity-related factors:

• Obstructive sleep apnoea (OSA) is a key concern due to BMI of 35, which increases the risk of airway obstruction and difficult intubation. Consider a modified Mallampati score, assessing for any signs of OSA, such as snoring or daytime fatigue.

• Assess neck circumference and thyromental distance, as these can help predict airway difficulty in obese patients.

Airway anatomy:

• Perform a mouth opening, mandibular protrusion test to assess for potential difficult intubation.

• Ensure no visible dental issues or anatomical obstructions that could complicate airway management.

Pneumoperitoneum considerations:

• Anticipate increased intra-abdominal pressure from insufflation, which can impede diaphragmatic movement and limit lung compliance. Be prepared for ventilation changes during the procedure.

Ventilation plan:

• Consider using rapid-sequence induction (RSI) for induction to minimize aspiration risk.

• Prepare for airway adjuncts like an oral or nasal airway or LMA in case of difficulty maintaining ventilation.

Positioning:

• Position the patient head-up for optimal respiratory mechanics, and ensure the head and neck are in a neutral position to avoid airway obstruction.

What specific considerations would you take for managing ventilation in this patient, particularly in the context of obesity?

• Pre-oxygenation: Use high-flow oxygen for 5 minutes pre-induction to maximize oxygen reserves.

• Obesity reduces functional residual capacity and increases the risk of hypoxia. Position the patient to facilitate optimal ventilation—consider head elevation and ensure adequate padding to maintain the neutral position of the neck.

• Ventilation:

  • Be prepared for reduced lung compliance with increased intra-abdominal pressure due to pneumoperitoneum.

  • Controlled ventilation with low tidal volumes may be required. Consider positive end-expiratory pressure (PEEP) to support oxygenation during pneumoperitoneum.

  • Watch for hypercapnia (increased CO₂) and plan for rapid ventilation adjustments if CO₂ rise

What would be your immediate actions if the CO₂ trace is lost after commencing surgery?

Check the equipment:

• Ventilator circuit: Ensure that there are no kinks or disconnections in the circuit.

• Endotracheal tube (ETT): Confirm the ETT placement (check capnography, chest rise, and auscultation to verify correct positioning).

• Ensure that the CO₂ detector or sensor is functioning correctly.

Patient assessment:

• Check for signs of ventilatory compromise (e.g., saturation drop, increased airway pressures, or end-tidal oxygen).

• Auscultate the chest to detect signs of airway obstruction (e.g., bronchospasm, ETT displacement).

Consider other causes:

• Pneumothorax: Check for signs of tension pneumothorax (e.g., unilateral chest expansion, hypotension, tachypnoea).

• Aspiration: Look for signs of aspiration or pulmonary oedema.

• Circulatory issues: Check for hypotension or cardiac arrest, which may explain a loss of circulation-related CO₂.

Temporary measures:

• Ventilate manually to assess for airway patency or consider an adjustment in ventilation settings to correct the issue.

• If no resolution is found, consider reintubating or securing the airway with alternative devices (e.g., LMA).

What criteria would you use to assess readiness for extubation?

• Spontaneous breathing: Confirm that the patient is breathing spontaneously with adequate tidal volumes and respiratory rate.

• Adequate airway reflexes: Check for cough reflex and gag reflex to ensure airway protection post-extubation.

• Hemodynamic stability: Ensure stable blood pressure and heart rate with no signs of shock or distress.

• Saturation: Verify that oxygen saturation is above 90% on room air or appropriate oxygen supplementation.

• Sedation levels: The patient should be adequately awake and alert, able to follow commands.

What would you do if the patient develops difficulty breathing or shows signs of airway obstruction in PACU?

Assess the airway:

• Check for signs of airway obstruction (e.g., stridor, increased work of breathing, cyanosis).

• Consider airway positioning: Adjust head position or try a jaw thrust to relieve any obstruction.

Interventions:

• Administer 100% oxygen via a non-rebreather mask.

• If obstruction persists, consider inserting an oral or nasopharyngeal airway or LMA.

• Suction any secretions from the airway if they are contributing to obstruction.

• If the patient is unresponsive or continues to deteriorate, consider bag-mask ventilation and prepare for intubation if needed.

• Sedation reversal: If oversedation is suspected, administer appropriate reversal agents (e.g., flumazenil or naloxone, depending on the agent used).

• Monitor: Ensure the patient is stable before moving to a lower level of care or transferring to a general ward.

What would be your plan for the patient’s post-operative disposition and handover?

Post-operative monitoring:

• Continue close monitoring of respiratory status, oxygen saturation, and hemodynamics.

• Handover to nursing staff: Provide a detailed handover, emphasizing any airway concerns, potential respiratory depression, and sedation levels.

Special considerations:

• Ensure that the patient’s BMI and potential for OSA are communicated to staff, with a focus on airway management and respiratory monitoring.

Pain management:

• Discuss a plan for multimodal analgesia (e.g., opioids, paracetamol, NSAIDs) for pain control, especially in the context of obesity, and adjust opioid dosing as needed for obesity-related drug sensitivities.