Use of One-Lung Ventilation for Thoracic Surgery

Yanping Duan, M.D., CA-2

Charles Smith, M.D.

Department of Anesthesiology

MetroHealth Medical Center

Objectives

• Indication/contraindication of OLV

• Physiology changes of OLV

• Selection of the methods for OLV

• Management of common problems associated with OLV, especially hypoxemia

Introduction

• One-lung ventilation, OLV, means separation of the two lungs and each lung functioning independently by preparation of the airway

• OLV provides:– Protection of healthy lung from infected/bleeding one

– Diversion of ventilation from damaged airway or lung

– Improved exposure of surgical field

• OLV causes:– More manipulation of airway, more damage

– Significant physiologic change and easily development of hypoxemia

Indication • Absolute

– Isolation of one lung from the other to avoid spillage or contamination

• Infection

• Massive hemorrhage

– Control of the distribution of ventilation

• Bronchopleural fistula

• Bronchopleural cutaneous fistula

• Surgical opening of a major conducting airway

• giant unilateral lung cyst or bulla

• Tracheobronchial tree disruption

• Life-threatening hypoxemia due to unilateral lung disease– Unilateral bronchopulmonary lavage

Indication (continued)• Relative

– Surgical exposure ( high priority)• Thoracic aortic aneurysm

• Pneumonectomy

• Upper lobectomy

• Mediastinal exposure

• Thoracoscopy

– Surgical exposure (low priority)• Middle and lower lobectomies and subsegmental resections

• Esophageal surgery

• Thoracic spine procedure

• Minimal invasive cardiac surgery (MID-CABG, TMR)

– Postcardiopulmonary bypass status after removal of totally occluding chronic unilateral pulmonary emboli

– Severe hypoxemia due to unilateral lung disease

Physiology of the LDP

• Upright position LDP, lateral decubitus position

Physiology of LDP

Awake/closed chest Anesthetized . V Q V Q V Q

ND

D

Summary of V-Q relationships in the anesthetized, open-chest and paralyzed patients

in LDP

Physiology of OLV• The principle physiologic change of OLV is the redistribution of

lung perfusion between the ventilated (dependent) and blocked (nondependent) lung

• Many factors contribute to the lung perfusion, the major determinants of them are hypoxic pulmonary vasoconstriction, HPV and gravity.

HPV• HPV, a local response of pulmonary artery smooth muscle,

decreases blood flow to the area of lung where a low alveolar oxygen pressure is sensed.

• The mechanism of HPV is not completely understood. Vasoactive substances released by hypoxia or hypoxia itself (K+ channel) cause pulmonary artery smooth muscle contraction

• HPV aids in keeping a normal V/Q relationship by diversion of blood from underventilated areas, responsible for the most lung perfusion redistribution in OLV

• HPV is graded and limited, of greatest benefit when 30% to 70% of the lung is made hypoxic.

• But effective only when there are normoxic areas of the lung available to receive the diverted blood flow

Factors Affecting Regional HPV

• HPV is inhibited directly by volatile anesthetics (not N20), vasodilators (NTG, SNP, dobutamine, many ß2-agonist), increased PVR (MS, MI, PE) and hypocapnia

• HPV is indirectly inhibited by PEEP, vasoconstrictor drugs (Epi, dopa, Neosynephrine) by preferentially constrict normoxic lung vessels

Gravity and V-Q• Upright LDP

Shunt and OLV• Physiological (postpulmonary) shunt

• About 2-5% CO,

• Accounting for normal A-aD02, 10-15 mmHg

• Including drainages from – Thebesian veins of the heart

– The pulmonary bronchial veins

– Mediastinal and pleural veins

• Transpulmonary shunt increased due to continued perfusion of the atelectatic lung and A-aD02 may increase

Two-lung Ventilation and OLV

Methods of OLV

• Double-lumen endotracheal tube, DLT

• Single-lumen ET with a built-in bronchial blocker, Univent Tube

• Single-lumen ET with an isolated bronchial blocker– Arndt (wire-guided) endobronchial blocker set– Balloon-tipped luminal catheters

• Endobronchial intubation of a single-lumen ET

DLT

• Type:– Carlens, a left-sided + a carinal hook

– White, a right-sided Carlens tube

– Bryce-Smith, no hook but a slotted cuff/Rt

– Robertshaw, most widely used

• All have two lumina/cuffs, one terminating in the trachea and the other in the mainstem bronchus

• Right-sided or left-sided available• Available size: 41,39, 37, 35, 28 French (ID=6.5,

6.0, 5.5, 5.0 and 4.5 mm respectively)

Left DLT…• Most commonly used• The bronchial lumen is longer, and a simple round opening and symmetric cuff Better margin of

safety than Rt DLT• Easy to apply suction and/or CPAP to either lung• Easy to deflate lung• Lower bronchial cuff volumes and pressures• Can be used

– Left lung isolation:

clamp bronchial +

ventilate/ tracheal lumen– Right lung isolation:

clamp tracheal +

ventilate/bronchial lumen

…Left DLT• More difficult to insert (size and curve, cuff)• Risk of tube change and airway damage if kept in

position for post-op ventilation• Contraindication:

– Presence of lesion along DLT pathway

– Difficult/impossible conventional direct vision intubation

– Critically ill patients with single lumen tube in situ who cannot tolerate even a short period of off mechanical ventilation

– Full stomach or high risk of aspiration

– Patients, too small (<25-35kg) or too young (< 8-12 yrs)

Univent Tube...• Developed by Dr. Inoue

• Movable blocker shaft in external lumen of a single-lumen ET tube

• Easier to insert and properly position than DLT (diff airway, C-s injury, pedi or critical pts)

• No need to change the tube for postop ventilation

• Selective blockade of some lobes of the lung

• Suction and delivery CPAP to the blocked lung

...Univent Tube

• Slow deflation (need suction) and inflation (short PPV or jet ventilation)

• Blockage of bronchial blocker lumen

• Higher endobronchial cuff volumes +pressure (just-seal volume recommended)

• Higher rate of intraoperative leak in the blocker cuff

• Higher failure rate if the blocker advanced blindly

Arndt Endobronchial Blocker set• Invented by Dr. Arndt, an anesthesiologist• Ideal for diff intubation, pre-existing ETT and

postop ventilation needed • Requires ETT > or = 8.0 mm• Similar problems as Univent• Inability to suction or ventilate the blocked lung

Other Methods of OLV

• Single-lumen ETT with a balloon-tipped catheter– Including Fogarty embolectomy catheter, Magill or

Foley, and Swan-Ganz catheter (children < 10 kg)

– Not reliable and may be more time-consuming

– Inability to suction or ventilate the blocked lung

• Endobronchial intubation of single-lumen ETT– The easiest and quickest way of separating one lung

from the other bleeding one, esp. from left lung

– More often used for pedi patients

– More likely to cause serious hypoxemia or severe bronchial damage

Management of OLV...Initial management of OLV anesthesia:

– Maintain two-lung ventilation as long as possible

– Use FIO2 = 1.0

– Tidal volume, 10 ml/kg (8-12 ml/kg)

– Adjust RR (increasing 20-30%) to keep PaCO2 = 40 mmHg

– No PEEP (or very low PEEP, < 5 cm H2O)

– Continuous monitoring of oxygenation and ventilation (SpO2, ABG and ET CO2)

...Management of OLV• If severe hypoxemia occurs, following steps be taken

– Check DLT position with FOB

– Check hemodynamic status

– CPAP (5-10 cm H2O, 5 L/min) to nondependent lung, most effective

– PEEP (5-10 cm H2O) to dependent lung, least effective

– Intermittent two-lung ventilation

– Clamp pulmonary artery ASAP

• Other causes of hypoxemia in OLV– Mechanical failure of 02 supply or airway blockade

– Hypoventilation

– Resorption of residual 02 from the clamped lung

– Factors that decrease Sv02 (CO, 02 consumption)

Broncho-Cath CPAP System

Summary• OLV widely used in cardiothoracic surgery• Many methods can be used for OLV. Each of them

have advantages + disadvantages. Optimal methods depends on indication, patient factors, equipment, skills + training

• FOB is the key equipment for OLV • Principle physiologic change of OLV is the

redistribution of pulmonary blood flow to keep an appropriate V/Q match

• Management of OLV is a challenge for the anesthesiologist, requiring knowledge, skill, vigilance, experience, and practice