Residency · Residency · Anesthesiology
One-Lung Ventilation and Thoracic Anesthesia
Introduction
One-lung ventilation (OLV) is a cornerstone technique in thoracic anesthesia, enabling surgical access to the hemithorax while presenting unique physiological challenges. The anesthesiologist must master lung isolation devices, ventilatory strategies, and the management of hypoxemia during OLV to ensure safe patient outcomes.
Indications for One-Lung Ventilation
Absolute Indications
Absolute indications include isolation of one lung to prevent contamination (massive hemorrhage, infection, whole-lung lavage), control of ventilation distribution (bronchopleural fistula, giant unilateral bullae, tracheobronchial disruption), and unilateral bronchopulmonary lavage for pulmonary alveolar proteinosis.
Relative Indications
Relative indications include surgical exposure for thoracic procedures such as lobectomy, pneumonectomy, and esophagectomy. Video-assisted thoracoscopic surgery (VATS), thoracic aortic aneurysm repair, mediastinal mass resection, and thoracic spine surgery via an anterior approach also benefit from OLV.
Lung Isolation Devices
Double-Lumen Endotracheal Tubes (DLTs)
The DLT is the most commonly used device for OLV. It is available as left-sided and right-sided, with left-sided preferred due to easier positioning. Right-sided DLTs have a slot for the right upper lobe bronchus and are more technically challenging. Sizes range from 35 to 41 French and are selected based on patient height and tracheal diameter. Confirmation of position requires fiberoptic bronchoscopy after initial placement and after repositioning.
Bronchial Blockers
Bronchial blockers include the Arndt blocker (wire-guided), Cohen blocker (deflecting tip), and Uniblocker. They are placed through a standard single-lumen ETT. Their advantages include no tube exchange requirement, usefulness for difficult airways, and compatibility with tracheostomies. Disadvantages include slower lung collapse, inability to suction the operative lung effectively, and susceptibility to dislodgement.
Univent Tube
The Univent tube is a single-lumen ETT with an integrated bronchial blocker channel. It is less commonly used but provides both single- and double-lumen functionality.
| Feature | Double-Lumen Tube (DLT) | Bronchial Blocker |
|---|---|---|
| Lung isolation quality | Excellent | Good (may be slower) |
| Lung collapse speed | Rapid (suction through lumen) | Slower |
| Suctioning operative lung | Yes (through bronchial lumen) | Limited |
| Difficult airway compatibility | Poor (large, rigid) | Excellent (use with existing SL-ETT) |
| Tube exchange required | Yes (from SL-ETT) | No |
| Sizing | 35–41 Fr based on height | Universal (fits through ≥7.0 ETT) |
| Position stability | Good once confirmed | Prone to dislodgement |
| Confirmation method | Fiberoptic bronchoscopy | Fiberoptic bronchoscopy |
| Preferred side | Left-sided preferred | Either side |
Physiology of One-Lung Ventilation
Hypoxic Pulmonary Vasoconstriction (HPV)
HPV diverts blood flow away from the non-ventilated lung toward the ventilated lung, reducing the shunt fraction from a theoretical 50% to approximately 20 to 25%. Inhibitors of HPV include volatile anesthetics (dose-dependent, minimal at less than 1 MAC), vasodilators, hypothermia, and infection. TIVA does not inhibit HPV.
Shunt and V/Q Mismatch
During OLV, the non-dependent (operative) lung is collapsed, creating an obligatory right-to-left shunt. Factors that worsen the shunt include surgical compression of the dependent lung, atelectasis, excessive tidal volume, and fluid overload. The lateral decubitus position favors ventilation of the dependent lung due to gravity but also compresses it.
Ventilatory Management During OLV
Protective Lung Ventilation Strategy
Tidal volume is set at 5 to 6 mL/kg ideal body weight for the single lung. PEEP of 5 to 10 cmH2O is applied to the dependent lung. FiO2 is titrated to maintain SpO2 above 90% while avoiding unnecessary hyperoxia. Peak airway pressures are kept below 30 cmH2O if possible. The respiratory rate is adjusted to maintain normocapnia, and permissive hypercapnia is acceptable.
Management of Hypoxemia During OLV
The first step is to verify DLT or blocker position with fiberoptic bronchoscopy, as malposition is the most common correctable cause. FiO2 is increased to 1.0. CPAP of 5 to 10 cmH2O is applied to the operative (non-dependent) lung. PEEP to the dependent lung is optimized, with a recruitment maneuver followed by decremental PEEP. Intermittent re-inflation of the operative lung may be considered. If pneumonectomy is planned, clamping the pulmonary artery eliminates the shunt.
Thoracic Anesthesia: Perioperative Considerations
Preoperative Assessment
Pulmonary function tests should include FEV1 and DLCO, with predicted postoperative values calculated (ppoFEV1 above 40% predicted is acceptable). Cardiopulmonary exercise testing is valuable, with a VO2max above 15 mL/kg/min considered favorable for lung resection. Split-function studies using quantitative V/Q scanning help predict postoperative lung function.
Analgesia for Thoracic Surgery
Thoracic epidural analgesia is the gold standard for open thoracotomy, placed at the T5 to T8 level. The paravertebral nerve block provides comparable analgesia with fewer hemodynamic side effects. The erector spinae plane (ESP) block is an emerging alternative that is easier to perform and has a favorable safety profile. The serratus anterior plane block is useful for VATS port sites. Multimodal analgesia includes acetaminophen, NSAIDs, ketamine infusion, and gabapentinoids.
Postoperative Complications
Post-pneumonectomy pulmonary edema is prevented by limiting IV fluids to less than 2 L intraoperatively. Other complications include bronchopleural fistula, cardiac herniation (after right pneumonectomy), atrial fibrillation (the most common cardiac arrhythmia after thoracic surgery), persistent air leak, empyema, and recurrent laryngeal nerve injury.
Clinical Pearls
DLT position should always be confirmed with fiberoptic bronchoscopy after placement, after positioning, and whenever oxygenation or ventilation deteriorates. Lung-protective ventilation with low tidal volumes during OLV reduces the incidence of acute lung injury and is now the standard of care. The most common cause of hypoxemia during OLV is malposition of the lung isolation device, and this should be checked first before escalating interventions. Thoracic epidural analgesia improves postoperative respiratory mechanics and reduces pulmonary complications after open thoracotomy.
References
- Slinger PD, Campos JH. Anesthesia for thoracic surgery. In: Gropper MA, ed. Miller's Anesthesia. 9th ed. Elsevier; 2020. Chapter 53.
- Lohser J, Slinger P. Lung injury after one-lung ventilation: a review of the pathophysiologic mechanisms affecting the ventilated and the collapsed lung. Anesth Analg. 2015;121(2):302-318.
- Sentürk M, Slinger P, Cohen E. Intraoperative mechanical ventilation strategies for one-lung ventilation. Best Pract Res Clin Anaesthesiol. 2015;29(3):357-369.
- Batchelor TJP, Rasburn NJ, Abdelnour-Berchtold E, et al. Guidelines for enhanced recovery after lung surgery. Eur J Cardiothorac Surg. 2019;55(1):91-115.