ONE LUNG VENTILATION (OLV)-SEPARATION
Why & How ?
By
Ahmed Ibrahim ; M.D.
Prof.of Anaesthesia
Ain Shams University

OLV means:



OLV provides:




separation of the two lungs
each lung functions independently by preparation of the airway
protection of healthy lung from infected/bleeding one
diversion of ventilation away from damaged airway or lung
improved exposure of surgical field
OLV causes:


more manipulation of airway, more damage
significant physiologic change & easy development of hpoxaemia
Indications for OLV
ABSOLUTE
1. Isolation of one lung from the other to avoid spillage or contamination.
2. Control of the distribution of ventilation (fistula, cyst, T.B disruption…).
3. Unilateral bronchopulmonary lavage.
RELATIVE
1. Surgical exposure.
2. Postcardiopulmonary bypass status, after removal of totally occluding chronic
unilateral pulmonary emboli.
OLV is achieved
by either;
-Double lumen ETT (DLT)
-Bronchial blocker
-Endobronchial tube
Anatomy of the Tracheobronchial Tree
Features of DLT
RUL, right upper lobe;
LUL, left upper lobe
Carlens DLT
Robertshaw DLT
Different types of DLT
Carlens
White
Bryce Smith
Robertshaw
hook
+
+
-
-
side
Lt
Rt
Lt & Rt
Lt & Rt
lumen
Basic pattern of a Right-Sided DLT
Rt
Lt
Lt
passage of the left-sided DLT
guide for Length and Size of DLT
Length of tube ,
For 170 cm height, tube depth of 29 cm
For every 10 cm height change , 1 cm depth change
Patient characteristics
Tracheal width (mm):
Tube size (Fr gauge)
18
16
15
14
41
39
37
35
4’ 6”-5’5”
5’5”-5’10”
5’11”-6’4”
35-37
37-39
39-41
Patient height
Patient age (year)
13-14
12
10
8
35
32
28 (lt only)
26 (lt only)
Check Position of Lt -DLT
Checklist for tracheal placement
a. inflate tracheal cuff
b. ventilate rapidly by hand
c. check that both lungs are being
ventilated
d. If not, withdraw 2-3 cm & repeat
Checklist for Lt side
a. inflate Lt cuff > 2ml
b. ventilate and check bilateral
breath sounds
c. clamp Rt tube
d. check unilateral (Lt) breath
sounds
Checklist for Rt side
a. clamp Lt tube
b. check unilateral (Rt) breath
sounds
Major Malpositions of a Lt- DLT
Lt
Breath Sounds Heard
Both cuffs inflated
Clamp Rt lumen
Left
Left
Both
Right
Both cuffs inflated
Clamp Lt lumen
Right
None / Very
minimal
None / Very
minimal
None / Very
minimal
Deflate Lt cuff
Clamp Lt lumen
Both
left
Both
Right
To ensure correct position of DLT clinically :

breath sounds are
- normal (not diminished) &
- follow the expected unilateral pattern with unilateral clamping

the chest rises and falls in accordance with the breath sounds

the ventilated lung feels reasonably compliant

no leaks are present

respiratory gas moisture appears and disappears with each tidal
ventilation
N.B even if the DLT is thought to be properly positioned by clinical signs,
subsequent FOB may reveal an incidence of malposition ( 38 -78 %)
FOB picture of Lt - DLT
FOB picture of Rt DLT
Relationship of FOB Size to Adult DLT
FOB Size (mm)
Adult DLT Size
(OD)
(French)
5.6
All sizes
4.9
3.6–4.2
41
39
37
35
All sizes
Fit of FOB inside DLT
Does not fit
Easy passage
Moderately easy passage
Tight fit, need lubricant, hard push
Does not fit
Easy passage
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..).
Adequacy for Sealing (air Bubble test )
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
to avoid Tracheobronchial tree Disruption ;
1. Be cautious in patients with bronchial wall abnormalities.
2. Pick an appropriately sized tube.
3. Be sure that tube is not malpositioned ; Use FOB.
4. Avoid overinflation of endobronchial cuff.
5. Deflate endobronchial cuff during turning.
6. Inflate endobronchial cuff slowly.
7. Inflate endobronchial cuff with inspired gases.
8. Do not allow tube to move during turning.
Relative Contraindications to Use of DLT

full stomach (risk of aspiration);

lesion (stricture, tumor) along pathway of DLT (may be traumatized);

small patients;

anticipated difficult intubation;


extremely critically ill patients who have a single-lumen tube already
in place and who will not tolerate being taken off mechanical
ventilation and PEEP even for a short time;
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.
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.
Indications for Use of Bronchial Blockers
1st , limitations to DLT (severely distorted airway, small patients ,
anticipated difficult intubation)
2nd , to avoid a risky change of DLT to single-lumen tube
•
•
whenever postoperative ventilation is anticipated
in cases of thoracic spine surgery in which a thoracotomy in the
supine or LDP is followed by surgery in the prone position.
3rd , situations in which both lungs may need to be
blocked (e.g., bilateral operations, indecisive surgeons).
Types of bronchial blockers

Univent bronchial blocker system

Arndt endobronchial blocker

Cohen Flexitip Endobronchial Blocker

BB independent of a single-lumen tube
Univent bronchial blocker system
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
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
LIMITATION
SOLUTION
1. 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 air
5. Leak in BB cuff
Make sure BB cuff is subcarinal, increase inflation volume,
rearrange surgical field
Arndt endobronchial blocker
[Wire guided Endobronchial Blocker (WEB)]
Cohen Flexitip Endobronchial Blocker
Bronchial Blockers that are Independent of a
Single-Lumen Tube
Adults
-Fogarty (embolectomy) catheter with a 3 ml balloon.
It includes a stylet so that it is possible to place a curvature at the distal tip to
facilitate entry into the larynx and either mainstem bronchus .
-balloon-tipped luminal catheters (such as Foley type) may be used as bronchial blockers.
Very small children (10 kg or less)
- Fogarty catheter with a 0.5 ml balloon
- Swan-Ganz catheter (1 ml balloon)
*
these catheters have to be positioned under direct vision; a FOB method is perfectly
acceptable; the FOB outside diameter must be approximately 2 mm to fit inside the
endotracheal tube (3 mm internal diameter or greater).
Otherwise, the bronchial blocker must be situated with a rigid bronchoscope.
*
Paediatric patients of intermediate size require intermediate size occlusion catheters and
judgment on the mode of placement (i.e., via rigid versus FOB).
Lung separation with a single-lumen tube, FOB, and
Rt lung bronchial blocker
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.
Endobronchial Intubation with Single-Lumen Tubes

In adults, is often the easiest, quickest way for lung separation in
patients presenting with haemoptysis , either
-blind, or
-FOB , or
-guidance by surgeon from within chest

In children it may be the simplest way to achieve OLV
Disadvantages
-inability to do suctioning or ventilation of operative side.
-difficult positioning bronchial cuff with inadequate ventilation of
Rt upper lobe after Rt endobronchial intubation.
In summary,
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) .
Physiology of OLV
(Arterial Oxygenation and Carbon Dioxide Elimination)
Blood passing through :


non ventilated lung , retains CO2 and does not take O2.
over ventilated 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(Aa)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.
Blood Flow distribution during OLV
The major determinants of
blood
flow
distribution
between both lungs :
•gravity,
•amount of lung disease,
•magnitude HPV,
•surgical interference nondependent ,
•ventilation mode dependent
Blood Flow Distribution During OLV , cont….
 Lung
condition (amount of
lung disease)
*severely diseased nondependent lung, may have a
fixed reduction in blood flow preoperatively and its
collapse may not cause much increase in shunt.
*increases in PVR in dependent ventilated lung
decreases its ability to accept redistributed blood from the
hypoxic lung. This may occur in case of :
-decreasing FIO2 in the dependent lung .
-decreasing temperature .
Blood Flow Distribution During OLV , cont….
Also, development of a hypoxic compartment (area of low V/Q and
atelectasis) in the dependent lung increases its PVR (HPV), thereby
decreasing dependent lung and increasing nondependent lung blood flow.
This may develop intraoperatively for several reasons:
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.
Blood Flow Distribution During OLV , cont.

Surgical interference(compression ,retraction and

Mode of ventilation of dependent lung
•
•
•
ligation of pulmonary vessels during pulmonary
resection) of the nondependent lung may further
passively reduce its blood flow.
If hyperventilated
PaCO2
HPV
Excessive AWP (PEEP or VT )
dependent PVR and
nondependent lung blood flow.
FIO2
-VD in dependent lung, augmenting HPV in
nondependent lung
-but ,may cause absorption atelectasis in
regions that have low V/Q ratios
Blood Flow Distribution During OLV , cont.

•
•
•
Magnitude of HPV
HPV is an autoregulatory mechanism that protects the PaO2 by
decreasing the amount of shunt flow that can occur through
hypoxic lung as it diverts blood flow from the atelectatic lung
toward the remaining normoxic or hyperoxic ventilated lung.
HPV is of little importance When ;
-very little of the lung is hypoxic (near 0%) because shunt will be
small.
-most of the lung is hypoxic (near 100%) there is no significant
normoxic region to which the hypoxic region can divert flow.
Of great importance if
the percentage of hypoxic lung is
intermediate ( 30 and 70%), which is the case during OLV
Blood Flow Distribution During OLV , cont.
Factors that might determine the amount of regional HPV
Factors that might determine the amount of regional HPV , cont.
1. Distribution of the alveolar hypoxia is probably not a determinant of the amount of HPV; all
regions of the lung respond to alveolar hypoxia with vasoconstriction.
2. Atelectasis, most of blood flow reduction in acutely atelectatic lung is due to HPV and none of it
to passive mechanical factors (such as vessel tortuosity).
3. Vasodilator drugs, most of them inhibit regional HPV
4. Anaesthetic drugs
5. Pulmonary vascular pressure, HPV response is
-maximal at normal PVP and
-decreased at either high or low PVP.
6. Pv¯O2 , HPV response also is
-maximal when Pv¯O2 is normal and
-decreased by either high or low Pv¯O2.
7. FIO2
selectively decreasing the FIO2 in the normoxic compartment causes an increase in
normoxic lung vascular tone, thereby decreasing blood flow diversion from hypoxic to normoxic
lung.
8. Vasoconstrictor drugs constrict normoxic lung vessels preferentially, thereby disproportionately
increasing normoxic lung
PVR causing decrease normoxic lung blood flow and increase
atelectatic lung blood flow.
9. PaCO2 , hypocapnia inhibits & hypercapnia directly enhances regional HPV.
10. PEEP
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 DLT


Decrease of Pv¯O2 (decreased cardiac output, increased oxygen
consumption [excessive sympathetic nervous system stimulation,
hyperthermia, shivering])
Transfusion of blood may cause pulmonary dysfunction attributed to
the action of isoantibodies against leukocytes, which causes cellular
aggregation, microvascular occlusion, and capillary leakage.
Ventilatory Management of OLV

Conventional Ventilatory Management

Differential Lung Ventilation Management

High-Frequency Ventilation Management

Low-Flow Apnoeic Ventilation (Apnoeic
Insufflation)
Conventional Ventilatory Management
•Maintain two-lung ventilation as long as possible.
•Use FIO2 = 1.0
•Begin OLV with tidal volume of 10 ml / kg.
•Adjust respiratory rate so that PaCO2 ~ 40 mmHg.
•Continuous monitoring of oxygenation and ventilation.
Differential Lung Ventilation Management

Intermittent Inflation of the Nondependent Operative
Lung may be expected to increase PaO2 for a variable period of time.

Selective Dependent Lung PEEP

Selective Nondependent Lung CPAP

Differential Lung PEEP/CPAP
(without tidal ventilation)
Dependent lung is ventilated but compressed by :
Mediastinum , Diaphragm P ( rolls, packs, shoulder
supports) .The nondependent lung is nonventilated
, and blood flow through it is a shunt flow.
Selective CPAP to
nondependent lung permits
oxygen uptake from it ; Even if CPAP causes a rise in
PVR and diverts blood to dependent lung, the diverted
blood flow can still participate in gas exchange in the
ventilated dependent lung that greatly increases PaO 2
Selective PEEP to dependent lung improves V/Q
but also increases PVR in it ; this diverts blood and
increases shunt flow through, the nonventilated lung.
Differential lung CPAP (nondependent) /PEEP
(dependent), wherever blood goes, both lungs can
participate in O2 uptake. With this pattern, PaO2 can
be restored to levels near those achieved by twolung ventilation.
The three essential components of a
nondependent lung CPAP system
CPAP is created by the free flow of oxygen into the lung versus the restricted outflow of
oxygen from the lung by the pressure relief valve.
The Mallinckrodt Broncho-Cath CPAP System
(Photography courtesy of Mallinckrodt Medical, Inc., St. Louis, MO.)
Recommended Combined Conventional and
Differential Lung Management of OLV
1.
Maintain two-lung ventilation until pleura is opened
2. Dependant lung
•
•
•
•
3.
FIO2 = 1.0
VT = 10 ml / Kg
RR , so that PaCO2 ~ 40 mmHg
PEEP = 5 - 10 cmH2O
If severe hypoxaemia occurs
•
•
•
•
•
•
Check DLT position by FOB
Check haemodynamic status
Non dependant lung CPAP (5 - 10 cmH2O)
Dependent lung PEEP
Intermittent two lung ventilation
Clamp pulmonary artery (pneumonectomy)
High-Frequency Ventilation (HFV)
Management
HFV delivers , very small VT (<2 ml/kg)
at high rates (60 - 2,400 breaths/min)
So,
•
•
can be delivered through very small catheters
it decreases PAWP
So,
it may be uniquely useful in facilitating the performance of thoracic surgery in
the following three ways;
-Use in Major Conducting Airway Surgery
-Use in Bronchopleural Fistula
-Use in Minimizing Movement of the Operative Field
Types of HFV
TYPE OF HFV
RATE/MIN
TYPE OF
VENTILATOR
GAS
ENTRAINMENT
INSPIRATION
EXHALATION
HFPPV
60–100
Volume
No
Active
Passive
HFJV
100–400
Jet pulsation
Yes
Active
Passive
HFOV
400–2,400
Piston pump
Yes
Active
Active
100-600
Rotating ball
Yes
Active
Passive
HFI
Low-Flow Apnoeic Ventilation (Apnoeic Insufflation)


If ventilation is stopped during administration of 100 % O2 and
airway is left connected to a fresh gas supply, O2 will be drawn
into the lung by mass movement to replace the diffused O2 . There
is usually no difficulty in maintaining an adequate PaO2 (especially
if 5–10 cmH2O of CPAP is used) at least for 20 minutes .
If flow of O2 is relatively low (<0.1 L/kg/min) almost all CO2
produced is retained, and PaCO2 rises approximately 6 mmHg in
the 1st minute and then 3 - 4 mmHg each minute thereafter .

Safe period < 10 min

arterial oxygen saturation monitoring via pulse oximetry is
mandatory.