Presentation on theme: "ONE LUNG VENTILATION (OLV)-SEPARATION Why & How ?"— Presentation transcript:
1ONE LUNG VENTILATION (OLV)-SEPARATION Why & How ? ByAhmed Ibrahim ; M.D.Prof.of AnaesthesiaAin Shams University
2OLV means: OLV provides: OLV causes: separation of the two lungs each lung functions independently by preparation of the airwayOLV provides:protection of healthy lung from infected/bleeding onediversion of ventilation away from damaged airway or lungimproved exposure of surgical fieldOLV causes:more manipulation of airway, more damagesignificant physiologic change & easy development of hpoxaemia
3Indications for OLV ABSOLUTE RELATIVE 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.RELATIVE1. Surgical exposure.2. Postcardiopulmonary bypass status, after removal of totally occluding chronicunilateral pulmonary emboli.
4OLV is achieved by either; -Double lumen ETT (DLT)-Bronchial blocker-Endobronchial tube
14guide for Length and Size of DLT Length of tube , For 170 cm height, tube depth of 29 cmFor every 10 cm height change , 1 cm depth changePatient characteristicsTube size (Fr gauge)Tracheal width (mm):1816151441393735Patient height4’ 6”-5’5”5’5”-5’10”5’11”-6’4”35-3737-3939-41Patient age (year)13-14121083228 (lt only)26 (lt only)
15Check Position of Lt -DLT Checklist for tracheal placementa. inflate tracheal cuffb. ventilate rapidly by handc. check that both lungs are beingventilatedd. If not, withdraw 2-3 cm & repeatChecklist for Lt sidea. inflate Lt cuff > 2mlb. ventilate and check bilateralbreath soundsc. clamp Rt tubed. check unilateral (Lt) breathsoundsChecklist for Rt sidea. clamp Lt tubeb. check unilateral (Rt) breathsounds
16Major Malpositions of a Lt- DLT Breath Sounds HeardBoth cuffs inflatedClamp Rt lumenLeftRightBothLeftNone / Very minimalleftBothNone / Very minimalRightNone / Very minimalBoth cuffs inflatedClamp Lt lumenDeflate Lt cuffClamp Lt lumen
17To ensure correct position of DLT clinically : breath sounds are- normal (not diminished) &- follow the expected unilateral pattern with unilateral clampingthe chest rises and falls in accordance with the breath soundsthe ventilated lung feels reasonably compliantno leaks are presentrespiratory gas moisture appears and disappears with each tidal ventilationN.B even if the DLT is thought to be properly positioned by clinical signs, subsequent FOB may reveal an incidence of malposition ( %)
20Relationship of FOB Size to Adult DLT FOB Size (mm)(OD)Adult DLT Size (French)Fit of FOB inside DLT5.6All sizesDoes not fit4.941393735Easy passageModerately easy passageTight fit, need lubricant, hard push3.6–4.2
21Other 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..).
23Complications of DLT impediment to arterial oxygenation for OLV tracheobronchial tree disruption, due to-excessive volume and pressure in bronchial balloon-inappropriate tube size-malpositiontraumatic laryngitis (hook)inadvertent suturing of the DLT
24to 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.
25Relative 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.
26Bronchial 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 years old and weighing kg.Balloon-tipped luminal catheters have the advantage of allowing suctioning and injection of oxygen down the central lumen.
27Indications 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 tubewhenever postoperative ventilation is anticipatedin 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).
28Types of bronchial blockers Univent bronchial blocker systemArndt endobronchial blockerCohen Flexitip Endobronchial BlockerBB independent of a single-lumen tube
30steps 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
31Advantages of the Univent Bronchial Blocker Tube ( Relative to DLT ) 1. Easier to insert and properly position.2. Can be properly positioned during continuous ventilation andin the lateral decubitus position.3. No need to change the tube when turning from the supine toprone position or for postoperative mechanical ventilation.4. Selective blockade of some lobes of each lung.5. Possible to apply CPAP to nonventilated operative lung.
32Limitations to the Use of Univent Bronchial Blocker 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 ventilation2. Slow deflation time(a) Deflate BB cuff and compress and evacuate the lung through the main single lumen;(b) apply suction to BB lumen3. Blockage of BB lumen( blood, pus,..)Suction, stylet, and then suction4. High-pressure cuffUse just-seal volume of air5. Leak in BB cuffMake sure BB cuff is subcarinal, increase inflation volume, rearrange surgical field
37Bronchial 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).
38Lung separation with a single-lumen tube, FOB, and Rt lung bronchial blocker
39Disadvantages 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.
40Endobronchial 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 chestIn children it may be the simplest way to achieve OLVDisadvantages-inability to do suctioning or ventilation of operative side.-difficult positioning bronchial cuff with inadequate ventilation ofRt upper lobe after Rt endobronchial intubation.
41In 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) .
42Physiology 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 CO but cannot take up a proportionately increased amount of O2 .
43Thus, 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)O2usually 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 .
44Two-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.
45Blood 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
46Blood 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 .
47This may develop intraoperatively for several reasons: 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 hasa reduced volume resulting from combined factorsof induction of anaesthesia and circumferentialcompression by mediastinum ,abdominal contents, andsuboptimal 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.
48Blood 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 lungIf hyperventilated PaCO HPVExcessive 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
49Blood Flow Distribution During OLV , cont. Magnitude of HPVHPV 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
50Factors that might determine the amount of regional HPV Blood Flow Distribution During OLV , cont.Factors that might determine the amount of regional HPV
51Factors 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 HPV4. Anaesthetic drugs5. 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
52Other 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 secretionsMalposition of the DLTDecrease 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.
54Conventional Ventilatory Management Maintain two-lung ventilation as long as possible.Use FIO2 = 1.0Begin OLV with tidal volume of 10 ml / kg.Adjust respiratory rate so that PaCO2 ~ 40 mmHg.Continuous monitoring of oxygenation and ventilation.
55Differential 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 PEEPSelective Nondependent Lung CPAP (without tidal ventilation)Differential Lung PEEP/CPAP
56Dependent 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 PEEP to dependent lung improves V/Q but also increases PVR in it ; this diverts blood and increases shunt flow through, the nonventilated lung.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 PaO2Differential 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.
57The 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.
58The Mallinckrodt Broncho-Cath CPAP System (Photography courtesy of Mallinckrodt Medical, Inc., St. Louis, MO.)
59Recommended Combined Conventional and Differential Lung Management of OLV Maintain two-lung ventilation until pleura is openedDependant lungFIO2 = 1.0VT = 10 ml / KgRR , so that PaCO2 ~ 40 mmHgPEEP = cmH2OIf severe hypoxaemia occursCheck DLT position by FOBCheck haemodynamic statusNon dependant lung CPAP ( cmH2O)Dependent lung PEEPIntermittent two lung ventilationClamp pulmonary artery (pneumonectomy)
60High-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 cathetersit decreases PAWPit may be uniquely useful in facilitating the performance of thoracic surgery inthe following three ways;-Use in Major Conducting Airway Surgery-Use in Bronchopleural Fistula-Use in Minimizing Movement of the Operative Field
61Types of HFV HFPPV HFJV HFOV HFI 60–100 Volume No Active Passive TYPE OF HFVRATE/MINTYPE OF VENTILATORGAS ENTRAINMENTINSPIRATIONEXHALATIONHFPPV60–100VolumeNoActivePassiveHFJV100–400Jet pulsationYesHFOV400–2,400Piston pumpHFIRotating ball
62Low-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 mmHg each minute thereafter .Safe period < 10 min arterial oxygen saturation monitoring via pulse oximetry is mandatory.