CHAPTER 39: Lung Separation in the Patient with a Difficult Airway

CASE PRESENTATION

A 45-year-old female presents for a video-assisted thoracoscopic (VATS) left upper lobectomy. She has a history of severe obstructive sleep apnea (OSA) and uses a continuous positive airway pressure (CPAP) machine. She is morbidly obese and her medical history is otherwise unremarkable. Echocardiography reveals normal pulmonary pressure. Her only medication is acetaminophen and she has no allergies.

On examination, she is 150 cm tall and weighs 120 kg (BMI 53 kg·m⁻²). Vital signs are: BP 140/80 mmHg, HR 69 beats per min and regular, RR 16 breaths per min, temperature 36.9ºC, and oxygen saturation is 99% on room air.

Airway examination reveals a Mallampati IV classification, mouth opening of 4 cm, thyromental distance of 4 cm, mandibular mobility of 2 cm, normal cervical spine extension, and full dentition. The chest is clear to auscultation and heart sounds are normal.

ANESTHESIA CONSIDERATIONS

Is This Patient Fit for Anesthesia?

A patient with morbid obesity would be expected to have OSA-related complications, including hypoventilation syndrome and pulmonary hypertension. Her normal echocardiogram is reassuring. Given she is compliant with CPAP therapy, she has no other significant comorbidities and needs no additional preoperative medical optimization.

What Anesthetic Technique Is Required?

General anesthesia is the standard of care for this procedure. Awake VATS has been reported^1,2 but is far from mainstream practice. Lung separation has been requested by the surgeon and is considered essential for successful surgical exposure.

How Can Lung Separation and One-Lung Ventilation (OLV) Be Achieved?

Lung separation and subsequent OLV for thoracic surgery can be achieved by a variety of techniques^3–6 and discussion with the health care team is an essential component in establishing a management plan. Successful lung separation can be dependent on patient factors, the surgical procedure proposed, user familiarity with lung separation equipment, upper airway anatomy, and user knowledge of endoscopic bronchial anatomy. Campos et al.⁷ looked at these factors and reported that knowledge of endoscopic bronchial anatomy was the main factor influencing lung separation success among anesthesia practitioners with limited thoracic experience. Emphasis should be placed on how the planned surgical procedure and the patient’s existing bronchial anatomy will interact with lung separation devices. A review of endoscopic bronchial anatomy has been published⁸ and a Virtual Bronchoscopy simulator can be found online at www.thoracicanesthesia.com or www.pie.med.utoronto.ca/VB.

Double-lumen tubes (DLTs) and bronchial blockers (BB) are considered standard methods of achieving lung separation. Although DLTs have long been considered the gold standard for lung separation, BBs have been shown to provide equivalent surgical exposure when compared to DLTs.⁹ The advantages and disadvantages of DLTs and BBs are numerous and well described in the literature.^10–15 A DLT is preferred over BBs when lung isolation is ...