one lung ventillation, problem based learning

ONE-LUNG VENTILATION(OLV): TECHNIQUE AND ANAESTHETIC

CONSIDERATIONS

Dr Varun Kumar Varshney

•Define one lung ventillation?

INTRODUCTION

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

1950 –Carlens design of DLT use for lung surgery.1960- Robertshaw introduced design

modifications for separate left and right-sided DLTs.

1980- Disposable DLTs made of PVC based on design of Robertshaw DLT.

Requires greater skill of the anesthesia team because of

oDifficult to place lung isolation equipmentoDifficulty to overcome hypoxic pulmonary

vasoconstriction in dependent lungoPatient population is comparably “sicker”

• 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 • Dependent Lung or Down Lung

• The lung that is ventilated• Non-dependent Lung or Up Lung

• The lung that is collapsed to facilitate the surgery

•Indication of one lung ventillation?

ABSOLUTE INDICATION FOR OLV

•Isolation of each lung to prevent contamination of a healthy• Infection (abscess, infected cyst)• Massive hemorrhage

•Control of the distribution of ventilation to only one lung• Bronchopleural fistula• Bronchopleural cutaneous fistula• Unilateral cyst or bullae• Major bronchial disruption or trauma

•Unilateral bronchopulmonary lavage•Video assisted thoracoscopic surgery(VATS)

RELATIVE INDICATION

•Surgical exposure ( high priority)• Thoracic aortic aneurysm• Pneumonectomy• Lung volume reduction• Mininmal invasive cardiac surgery• Upper lobectomy

•Surgical exposure (low priority)• Middle and lower lobectomies• Esophageal surgery• Mediastinal mass resection, thymectomy• Bilateral sympathectomies

•Devices?

OLV Devices

OLV is achieved by either;Double lumen ETT (DLT)Bronchial blocker Single-lumen ET with a built-in bronchial blocker• Univent TubeSingle-lumen ET with an isolated bronchial blocker• Arndt (wire-guided) endobronchial blocker set• Balloon-tipped luminal cathetersEndobronchial tube• Endobronchial intubation of a single-lumen ET

• Related Anatomy of tracheo-bronchial tree?

Anatomy of the Tracheobronchial Tree

Double Lumen Tube(DLT)

RUL, right upper lobe; LUL, left upper lobe

Rt Lt

• TYPES OF DLT?

•MOST COMMONLY USED DLT?

•SIZES AVAILABLE?

DLT Types• Type:

• Carlens, a left-sided + a carinal hook

• White, a right-sided Carlens tube

• Bryce-Smith, no hook but a slotted cuff

• Robertshaw, most widely used • All have two lumen and 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,

32,28,28French (ID=6.5, 6.0, 5.5, 5.0 and 4.5 mm respectively)

Basic pattern of a Right-Sided DLT

•COMPARE DIFFERENT TYPES OF DLT?

Different types of DLT

Carlens White Bryce Smith Robertshaw

Lumen Hook + + - -Side Lt Rt Lt & Rt Lt & Rt

•DIFFERENCE B/W RIGHT SIDE AND LEFT SIDE DLT?

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 for:

• Left lung isolation: clamp bronchial + ventilate/ tracheal lumen• Right lung isolation: clamp tracheal + ventilate/bronchial

lumen• More difficult to insert (size and curve, cuff)• Risk of tube change and airway damage if kept in position for

post-op ventilation

•Indication for RT sided DLT?

Right DLT• Left –sided DLT is used more commonly for most elective thoracic

procedures , Following are specific clinical situation in which Right –sided

DLT is indicated : Distorted Anatomy of the Entrance of Left Mainstem BronchusExternal or intraluminal tumor compressionDescending thoracic aortic aneurysmSite of Surgery Involving the Left Mainstem BronchusLeft lung transplantationLeft –sided tracheobronchial disruptionLeft –sided pneumonectomyLeft-sided sleeve resection

•PLACEMENT OF DLT?

DLT Placement•Prepare and check tube

Ensure cuff inflates and deflates• Lubricate tube • Insert tube with distal concave curvature facing

anteriorly• Remove stylet once through the vocal cords • Rotate tube 90 degrees (in direction of desired lung) • Advancement of tube ceases when resistance is

encountered. Average lip line is 29 ± 2 cm. • *If a carinal hook is present, must watch hook go

through cords to avoid trauma to them.

Passage of The Left-sided DLT

•CONFIRMATION OF PROPER PLACEMENT of LEFT sided DLT?

Check for placement of DLT• Check for placement by auscultation

• 3 STEP METHOD 1- Tracheal tube inflated-confirm b/l ventillation

2- tracheal lumen clamped, port distal to clamp opened,inflate bronchial cuff- auscultate to confirm unilateral ventillation.

3-Clamp removed,port closed-b/l breath sound.

Millers anaesthesia 8 E

Even if the DLT is thought to be properly positioned by clinical signs, subsequent FOB may reveal an incidence of malposition (38 -78 %)

•Importance of fibreoptic bronchoscope?

Check for placement of DLT

• Checking tube placement with the Fiberoptic Bronchoscope• Several situations exist where auscultation maneuvers are

impossible (patient is prepped and draped), or when they do not provide reliable information (preexisting lung disease so that breath sounds are not very audible, or if the tube is only slightly malpositioned)

• The double-lumen tube's precise position can be most reliably determined with the fiberoptic bronchoscope

• In patients with double-lumen tubes whose position seemed appropriate to auscultations, 48% had some degree of malposition. So always check position with fiberoptic

• After advancing the fiberoptic scope through the “tracheal” tube you should see the “bronchial blue balloon” in a semi lunar shape, just peeking out of the bronchus

•Other method to check DLT Placement?

Other Methods to Check DLT Position Chest radiograph;

may be more useful than conventional auscultation and clamping in some patients, but it is always less precise than FOB. The DLT must have radiopaque markers at the end of Rt and Lt lumina. Comparison of capnography;

waveform and ETCO2 from each lumen may reveal a marked discrepancy (different degree of ventilation). Surgeon; may be able to palpate, redirect or assist in changing DLT position from within the chest (by deflecting the DLT away from the wrong lung, etc..).

•HOW TO SELECT SIZE OF DLT?

Guide for Length and Size of DLTLength of tube: For 170 cm height, tube depth of 29 cm

For every 10 cm height change , 1 cm depth change

Patient characteristics Tube size (Fr gauge) Tracheal width (mm):

18161514

41393735

Patient height4’ 6”-5’5”5’5”-5’10”5’11”-6’4”

35-3737-3939-41

Patient age (year)13-14

12108

3532

28 (lt only) 26 (lt only)

•QUANTITATIVE ANALYSIS?

Adequacy for Sealing (Air Bubble test)

•Complications of DLT?

Complications of DLT

impediment to arterial oxygenation for OLV

tracheobronchial tree disruption, due to-excessive volume and pressure in bronchial balloon -inappropriate tube size-malposition

traumatic laryngitis (hook)

inadvertent suturing of the DLT

•How to avoid Tracheobronchial tree Disruption?

To avoid Tracheobronchial tree Disruption

Be cautious in patients with bronchial wall abnormalities.Pick an appropriately sized tube.Be sure that tube is not malpositioned ; Use FOB.Avoid overinflation of endobronchial cuff.Deflate endobronchial cuff during turning.Inflate endobronchial cuff slowly.Inflate endobronchial cuff with inspired gases. Do not allow tube to move during turning.

•Contraindication?

Contraindications

• Presence of lesion(stricture, tumor) 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)• patients having some combination of these problems.

Under these circumstances, it is still possible to separate the lungs by :

-using a single-lumen tube + FOB placement of a bronchial blocker ; or

-FOB placement of a single-lumen tube in a main stem bronchus.

•Advantage/Disadvantage of DLT?

Advantages of DLTRelatively easy to placeAllow conversion back and forth from OLV to two-lung

ventilation Allow suctioning of both lungs individuallyAllow CPAP to be applied to the non-dependent lungAllow PEEP to be applied to the dependent lung

Disadvantages of DLTCannot take patient to PACU or the UnitMust be changed out for a regular ETT if post-op ventilationCorrect positioning is dependent on appropriate size for

height of patient

Bronchial Blockers (With Single-Lumen Endotracheal Tubes)

Lung separation can be effectively achieved with the use of a single-lumen endotracheal tube and a FOB placed bronchial blocker.

Often necessary in children as DLTs are too large to be used in them. The smallest DLT available is a left-sided 26 Fr tube, which may be used in patients 8 -12 years old and weighing 25 -35 kg.

Balloon-tipped luminal catheters have the advantage of allowing suctioning and injection of oxygen down the central lumen.

•Different Types of bronchial blockers?

Types of bronchial blockers

Single-lumen ET with a built-in bronchial blocker• Univent TubeSingle-lumen ET with an isolated bronchial blocker• Arndt (wire-guided) endobronchial blocker set• Balloon-tipped luminal catheters

Cohen Flexitip Endobronchial Blocker

BB independent of a single-lumen tube

Univent Bronchial Blocker System

Univent Tubes

Univent Tubes• Endotracheal intubation can be performed in the

conventional manner, just like a single lumen endotracheal tube

• One-lung ventilation can be achieved by placement of the blocker to either the left or right lung, or to lung segments

• Blocked lung can be collapsed by aspirating air through the lumen of the blocker shaft

• The blocker can be retracted into its pocket to facilitate post-operative ventilation

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, Cervico-spinal injury, pediatric or critical patients)

• No need to change the tube for post-op 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

Steps of FOB-aided method of positioning the Univent bronchial blocker in lt main stem bronchus

One- or two-lung ventilation is achieved simply by inflating or deflating, respectively, the bronchial blocker balloon

Univent Tube

•Advantage of bronchial blocker over DLT?

Advantages of the Univent Bronchial Blocker Tube ( Relative to DLT )

1. Easier to insert and properly position.2. Can be properly positioned during continuous

ventilation and in the lateral decubitus position.3. No need to change the tube when turning from the

supine to prone position or for postoperative mechanical ventilation.

4. Selective blockade of some lobes of each lung.5. Possible to apply CPAP to nonventilated operative

lung.

•Limitations to the Use of Univent Bronchial Blocker ?

Limitations to the Use of Univent Bronchial Blocker

LIMITATION SOLUTION1. Slow inflation time (a) Deflate BB cuff and administer +ve pressure

breath through the main single lumen;(b) carefully administer one short high pressure (20–30 psi) jet ventilation

2. Slow deflation time (a) Deflate BB cuff and compress and evacuate the lung through the main single lumen; (b) apply suction to BB lumen

3. Blockage of BB lumen ( blood, pus,..)

Suction, stylet, and then suction

4. High-pressure cuff Use just-seal volume of air5. Leak in BB cuff Make sure BB cuff is subcarinal, increase inflation

volume, rearrange surgical field

•Arndt brochial blocker?

Arndt endobronchial blocker[Wire guided Endobronchial Blocker (WEB)]

Arndt Endobronchial Blocker set

Wire-Guided Endobronchial Blockers

• Invented by Dr. Arndt, an anesthesiologist so Arndt endobronchial blocker

• Ideal for difficult intubation, pre-existing ETT and postop ventilation needed

• Requires ETT ≥ 8.0 mm• Similar problems as Univent• Inability to suction or

ventilate the blocked lung• Available sizes

• Adult 9 Fr• Pediatric 5 Fr

Wire-Guided Endobronchial Blockers

•Indication of Wire Guided endobrochial Blockers?

Indications for Wire-Guided Endobronchial Blockers vs. DLT

Critically ill patientsRapid sequence induction(RSI)Known and unknown difficult airwayPostoperative intubationSmall adult and pediatric patientsObese adults

•Advantages of WEBs?

Advantages of WEBsQuickly and precisely navigate the airway

The pediatric bronchoscope acts as a guide, allowing the endobronchial blocker to be advanced over it into the correct position.

In addition, the wire-guided endobronchial blocker allows one-lung ventilation with a single-lumen endotracheal tube

• Thus, used in places of DLT or a Univent endotracheal tube• Allows OLV in the critically ill patient in whom reintubation

may be difficult or impossible • Unnecessary to convert from a conventional DLT to a single-

lumen tube at the end of surgery

Disadvantages of WEBs• Satisfactory bronchial seal and lung separation are

sometimes difficult to achieve

• The “blocked” lung collapses slowly (and sometimes incompletely)

• The balloon may become dislodged during surgery and enter the trachea proper, causing a complete airway obstruction

•Cohen Flexitip Endobronchial Blocker?

Cohen Flexitip Endobronchial Blocker

Disadvantages of a bronchial blockers as compared with DLT?

Disadvantages of a blocker that is independent of the single-lumen tube as

compared with DLT

inability to suction and/or to ventilate the lung distal to the blocker.

increased placement time. the definite need for a fiberoptic or rigid

bronchoscope.if bronchial blocker backs out into the trachea, the

seal between the two lungs will be lost and the trachea will be at least partially obstructed by the blocker, and ventilation will be greatly impaired.

E-Z Blocker?

The EZ-Blocker

• The EZ-blocker is a new BB that has a Y-shaped distal end.

• The peculiar characteristic of this device is that both distal ends are fitted with an inflatable cuff and a center hollow channel in each end.

• Therefore each inflatable balloon can be placed on the right or left mainstem bronchus, respectively.

• The shape of this balloon is spherical and there is only one size available at the present time, 7F.

DLT is the method of choice for lung separation in most adult patients. The precise location can be determined by FOB . In situations where insertion of a DLT may be difficult and/or dangerous, separating the lungs is achieved either with a single-lumen tube alone or in combination with a bronchial blocker (e.g., the Univent tube).

Therefore, regardless of what method of lung separation chosen, there is a real need of a small-diameter FOB (for checking the position of the DLT, placing a single-lumen tube in a mainstem bronchus, and placing a bronchial blocker) .

Summary of OLV devices

•Complication of one lung ventillation?

Complications of One Lung Ventilation

All difficult airway complicationsInjury to lips, mouth, teethInjury to airway mucosa from styletBronchial RuptureDecreased saturation

HPVInability to isolate lung

Physiology of OLV (Arterial Oxygenation and Carbon Dioxide Elimination)

Blood passing through:

Non Ventilated Lung,Non Ventilated Lung, retains CO2 and does not take O2.

Over Ventilated Over Ventilated Lung,Lung, gives off more than a normal amount of CO2 but cannot take up a proportionately increased amount of O2

Thus, during one-lung ventilation

more decreased oxygenation than during two-lung ventilation in LDP due to an obligatory Rt-Lt transpulmonary shunt through the nonventilated nondependent lung. Consequently,

lower PaO2 & larger P(A-a)O2

usually carbon dioxide elimination is not a problem; but

retention of CO2 by blood traversing the nonventilated lung

slightly exceeds the increased elimination of CO2 from blood

traversing the ventilated lung, and the PaCO2 will usually slowly

increase and P(A-a)CO2 decreases .

Two-lung ventilation versus OLV

during OLV, the nonventilated lung has some blood flow and therefore has an obligatory shunt, which is not present during two-lung ventilation & is the most important reason for increased P(A-a)O2.

Factors influencing pulmonary perfusion

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Many factors contribute to the lung perfusion, •hypoxic pulmonary vasoconstriction (HPV)•gravity, •amount of lung disease,•surgical interference in nondependent lung,•ventilation mode in dependent lung

The principle physiologic change of OLV is the redistribution of lung perfusion between the ventilated (dependent) and blocked (nondependent) lung.

1. in LDP ,ventilated dependent lung usually has a reduced volume resulting from combined factors of induction of anaesthesia and circumferential compression by mediastinum, abdominal contents, and suboptimal positioning effects (rolls, packs, supports). 2. absorption atelectasis can occur in regions with low V/Q when they are exposed to high FIO2 . 3. difficulty in secretion removal . 4.maintaining the LDP for prolonged periods may cause fluid to transude into the dependent lung and cause further decrease in lung volume and increase in airway closure.  

Hypoxic compartment may develop intraoperatively for several reasons:

Surgical interference(compression ,retraction and ligation of pulmonary vessels during pulmonary resection) of the nondependent lung may further passively reduce its blood flow.

Mode of ventilation of dependent lung•If hyperventilated, lead to decrease in PaCO2 that causes decrease in HPV•Excessive increase of AWP (PEEP or VT): increase dependent PVR and nondependent lung blood flow.•Increase FiO2 causes

• Vasodialatation in dependent lung, augmenting HPV in nondependent lung

• but ,may cause absorption atelectasis in regions that have low V/Q ratios

•Hypoxic pulmonary vasoconstriction?

Hypoxic Pulmonary Vasoconstriction (HPV)

•HPV, a physiological local response of pulmonary vascular smooth muscle (PVSM) to alveolar hypoxia,

•decreases blood flow to the area of lung where a low alveolar oxygen pressure is sensed and redistributes pulmonary blood flow from areas of low oxygen partial pressure to areas of high oxygen availability.

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•Mechanism of HPV?

• Intrinsic response of lung, no neuronal control, immediately present in transplanted lung.

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

• All pulmonary arteries and veins vasoconstrict in response to hypoxia, but greatest effect is to small pumonary arteries

•Benefits of HPV?

Hypoxic Pulmonary Vasoconstriction (HPV)…

• 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

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•Factors affecting HPV?

Factors affecting regional HPV

• HPV is inhibited directly by volatile anesthetics (not N20), vasodilators (NTG, SNP, NO, dobutamine, many ß2-agonist), increased PVR (MS, MI, PE) and hypocapnia

• HPV is indirectly inhibited by PEEP; vasoconstrictor drugs (epinephrine, norepinephrine, phenylephrine, dopamine) constrict normoxic lung vessels preferentially

Other Causes of Hypoxaemia During OLV

Failure of the oxygen supply. Gross hypoventilation of the dependent lung. Blockage of the dependent lung airway lumen e.g.

by secretions Malposition of the DLTResorption of residual O2 from the clamped lungDecrease of PvO2 (decreased cardiac output,

increased oxygen consumption [excessive sympathetic nervous system stimulation, hyperthermia, shivering)

•Management of Hypoxia during OLV?

Management of hypoxemia during OLV

• FiO2 = 1.0• Manual ventilation• 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

Summary•OLV widely used in cardiothoracic surgery•Many methods can be used for OLV. Optimal methods depends on indication, patient factors, equipment, skills and level of 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

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