ONE LUNG VENTILATION (OLV)-SEPARATION Why

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ONE LUNG VENTILATION (OLV)-SEPARATION Why How
?
By Ahmed Ibrahim M.D. Prof.of Anaesthesia Ain
Shams University
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• OLV means
• separation of the two lungs
• each lung functions independently by preparation
  of the airway
• OLV provides
• 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

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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.

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• OLV is achieved by either
• -Double lumen ETT (DLT)
• -Bronchial blocker
• -Endobronchial tube

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Anatomy of the Tracheobronchial Tree
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Features of DLT
RUL, right upper lobe LUL, left upper lobe
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Carlens DLT
Robertshaw DLT
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Different types of DLT
Carlens White Bryce Smith Robertshaw
lumen
hook - -
side Lt Rt Lt Rt Lt Rt
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Basic pattern of a Right-Sided DLT
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Rt
Lt
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Lt
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passage of the left-sided DLT
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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 Tube size (Fr gauge)
Tracheal width (mm) 18 16 15 14 41 39 37 35
Patient height 4 6-55 55-510 511-64 35-37 37-39 39-41
Patient age (year) 13-14 12 10 8 35 32 28 (lt only) 26 (lt only)
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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 gt 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
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Major Malpositions of a Lt- DLT
Lt
Breath Sounds Heard
Both cuffs inflated Clamp Rt lumen
Left None / Very minimal left
Left Right Both
Both None / Very minimal Both
Right None / Very minimal Right
Both cuffs inflated Clamp Lt lumen
Deflate Lt cuff Clamp Lt lumen
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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 )

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FOB picture of Lt - DLT
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FOB picture of Rt DLT
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Relationship of FOB Size to Adult DLT
FOB Size (mm) (OD) Adult DLT Size (French) Fit of FOB inside DLT
5.6 All sizes Does not fit
4.9 41 39 37 35 Easy passage Moderately easy passage Tight fit, need lubricant, hard push Does not fit
3.64.2 All sizes Easy passage
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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..).  

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Adequacy for Sealing (air Bubble test )
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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

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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.

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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.

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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.

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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).

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Types of bronchial blockers

• Univent bronchial blocker system
• Arndt endobronchial blocker
• Cohen Flexitip Endobronchial Blocker
• BB independent of a single-lumen tube

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Univent bronchial blocker system
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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
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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.

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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 (2030 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
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Arndt endobronchial blockerWire guided
Endobronchial Blocker (WEB)
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Cohen Flexitip Endobronchial Blocker
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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).

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Lung separation with a single-lumen tube, FOB,
and Rt lung bronchial blocker
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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.

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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.

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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) .
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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
  .

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• 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 .

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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.

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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

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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 .
•  

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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.  

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Blood Flow Distribution During OLV , cont.

• 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 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

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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

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Factors that might determine the amount of
regional HPV
Blood Flow Distribution During OLV , cont.
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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. PvO2 , HPV response also is
• -maximal when PvO2 is normal and
• -decreased by either high or low PvO2.
• 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.

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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 PvO2 (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.

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Ventilatory Management of OLV

• Conventional Ventilatory Management
• Differential Lung Ventilation Management
• High-Frequency Ventilation Management
• Low-Flow Apnoeic Ventilation (Apnoeic
  Insufflation)

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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.

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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 (without tidal
  ventilation)
• Differential Lung PEEP/CPAP

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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.
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 PaO2
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
two-lung ventilation.
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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.
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The Mallinckrodt Broncho-Cath CPAP
System (Photography courtesy of Mallinckrodt
Medical, Inc., St. Louis, MO.)
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Recommended Combined Conventional and
Differential Lung Management of OLV

• Maintain two-lung ventilation until pleura is
  opened
• Dependant lung
• 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)

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High-Frequency Ventilation (HFV) Management

• HFV delivers , very small VT (lt2 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

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Types of HFV
TYPE OF HFV RATE/MIN TYPE OF VENTILATOR GAS ENTRAINMENT INSPIRATION EXHALATION
HFPPV 60100 Volume No Active Passive
HFJV 100400 Jet pulsation Yes Active Passive
HFOV 4002,400 Piston pump Yes Active Active
HFI 100-600 Rotating ball Yes Active Passive
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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 510 cmH2O of CPAP
  is used) at least for 20 minutes .
• If flow of O2 is relatively low (lt0.1 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 lt 10 min 
• arterial oxygen saturation monitoring via pulse
  oximetry is mandatory.

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Good Bye