Lung Isolation - Method, Indications, and Contraindications.

Introduction

Lung isolation is a technique that involves either anatomic or physiologic separation of lungs with an airway device. It is performed to separate a diseased lung from a healthy lung or to access anatomic structures within the thoracic cavity. It helps create a surgical field and space within the thorax to access the structure.

What Is Lung Isolation?

Lung isolation is a procedure that allows both lungs to function as separate units. It separates one from the other using advanced airway devices like bronchial blockers or double-lumen endotracheal tubes. Lung isolation can be anatomic or physiologic separation. Anatomic isolation separates the diseased lung from healthy lungs and prevents contamination of healthy lungs by blood or pus from the diseased lung. Physiologic separation ventilates both lungs as a separate unit. It is done to create space and access the anatomic structures within the thorax.

Why Is Lung Isolation Done?

Lung isolation is done to maintain adequate gas exchange, prevent contamination with the healthy lung, and prevent barotrauma. Lungs are physiologically isolated to create a surgical field and access the structures in the thoracic cavity. It is done to manage lung diseases, thereby allowing the healthy lung to function as a separate unit to improve ventilation.

What Are the Indications for Lung Isolation?

The pathological indications for lung isolation include the following:

Anatomical lung isolation is indicated in the following conditions.

1. Condition like pulmonary alveolar proteinosis requires entire lung lavage.

2. Immense infectious or noninfectious secretions.

3. Pulmonary hemorrhage.

Physiologic lung isolation is indicated in the following cases:

1. Parenchymal disease or injury.

2. Unilateral bronchospasm.

3. Bronchopleural fistula.

4. Complications due to thoracic surgery.

The surgical indications for lung isolation include the following:

1. Lung resection.

2. Lung transplantation.

3. Video-assisted thoracoscopic surgery.

4. Pleurodesis or pleurectomy.

5. Thoracic diaphragmatic hernia repair.

6. Pericardiectomy.

7. Minimally invasive cardiac surgery.

8. Surgeries that involve the aorta in the thorax.

9. Thoracic sympathectomy.

10. Anterior approach to the spine.

What Are the Contraindications for Lung Isolation?

The contraindications for lung isolation include the factors related to double lumen endotracheal tube and the patient factors.

1. Difficult Airway - It is difficult to place the double-lumen endotracheal tube in patients with a difficult airway. Repeated attempts to place the tube may result in airway injury. Airway injury in a patient with difficult airway results in hypoxia.

2. Tracheostomy - Placement of double lumen endotracheal tube through a tracheostomy results in severe iatrogenic injury.

3. Intraluminal Tumors - Damage to the intraluminal tumors of the trachea or proximal bronchi during the placement of a double-lumen endotracheal tube can result in bleeding, tumor embolization, and tube occlusion.

4. Patients with hypoxia cannot tolerate lung isolation.

5. Patients with previous contralateral lobectomy and more than a 25 % decrease in lung function are contraindicated for lung isolation.

6. Patients with morbid obesity are contraindicated.

How Is Lung Isolation Performed?

Double-lumen endotracheal tubes and bronchial blockers are commonly used airway devices to perform lung isolation.

Double Lumen Endotracheal Tube - Direct laryngoscopy is the common technique to place the double lumen endotracheal tube. It can be placed via video laryngoscopy for patients with a difficult airway. The double-lumen tube is placed anteriorly while it passes the vocal cords. Auscultation helps to confirm the correct placement of a double-lumen tube. After correct placement, the bronchial lumen of the double-lumen tube is present in the mainstem bronchus. The bronchial cuff is then inflated to prevent its herniation over the carina. The tracheal lumen is open to the opposite side to allow selective ventilation to each lung. Right-side and left-side double-lumen endotracheal tubes are available. The right-sided double-lumen tube has a second opening on the bronchial lumen because of the early branch point of the right bronchus. Left-side double-lumen tubes are usually indicated to ensure proper positioning of the bronchial cuff to avoid occlusion of the bronchus. A right-side double lumen is indicated for left pneumonectomy. It is also indicated for procedures that involve the proximal left main bronchus that precludes the placement of the left-sided double-lumen tube.

Bronchial Blockers - Various models are available with an inflatable balloon at the end of the introducer that is advanced through a standard endotracheal tube or an endotracheal tube with a separate lumen containing the bronchial blocker. The bronchial blocker is advanced into either bronchus under fiberoptic guidance to provide lung isolation. It can also be advanced into the distal bronchus to isolate a particular lung segment selectively. The various bronchial blockers available are:

1. Wire Guided Device - The bronchial blocker is attached to the fiberoptic bronchoscope double-lumen into the desired bronchus.

2. Bronchial Blocker With an Incorporated Stylet - It is advanced through a single-lumen tube and directed to block a selective lobar bronchus. The stylet is removed after placement, and the lumen is used for the deflation of lobes or oxygen insufflation to apply continuous positive airway pressure to the deflated lobes.

3. Bronchial Blocker With Single Lumen Port - The balloon tip is flexed and directed into the desired bronchus under fiberoptic guidance.

4. Bronchial Blocker With Double-Lumen Port - This allows placement of the cuffs in the left and right bronchi. The desired bronchus is identified, and the appropriate cuff is inflated. The desired bronchus is identified under fiber-optic guidance.

What Are the Complications of Lung Isolation?

The double lumen endotracheal tube can cause the following complications:

1. Trauma to the trachea, larynx, or bronchi.
2. Iatrogenic tracheobronchial ruptures.
3. Postoperative hoarseness and sore throat.

Complications are common in double-lumen tubes because of their larger caliber compared to single-lumen endotracheal tubes.

Conclusion

Lung isolation is a procedure done to separate the lungs with an airway device. Appropriate techniques and devices ensure successful lung isolation. Lung isolation prevents the contamination of healthy lungs and offers a clear surgical field to access the anatomic structures in the thoracic cavity. It isolates the healthy lungs from diseased lungs and improves breathing ability, ventilation, and oxygen level. Advancements in lung isolation techniques offer the correct placement of devices and successful lung isolation.