Presentation on theme: "University College of Medical Sciences"— Presentation transcript:
1 University College of Medical Sciences Principle of thoracic anesthesia with determinants of operability for resection, One lung anesthesiaDr. Rajesh KumarUniversity College of Medical Sciences& GTB Hospital, Delhi
2 Objectives Indication/contraindication of OLV Physiological changes of OLVLung separation techniques and equipments
3 IntroductionOne-lung ventilation, OLV, means separation of the two lungs and each lung functioning independently.OLV provides:Protection of healthy lung from infected/bleeding oneDiversion of ventilation from damaged airway or lungImproved exposure of surgical fieldOLV causes:More manipulation of airway, more damageSignificant physiologic change and easily development of hypoxemia
4 IndicationAbsoluteIsolation of one lung from the other to avoid spillage or contaminationInfectionMassive hemorrhageControl of the distribution of ventilationBronchopleural fistulaBronchopleural cutaneous fistulaSurgical opening of a major conducting airwaygiant unilateral lung cyst or bullaTracheobronchial tree disruptionLife-threatening hypoxemia due to unilateral lung diseaseUnilateral bronchopulmonary lavage
5 Indication (continued) RelativeSurgical exposure ( high priority)Thoracic aortic aneurysmPneumonectomyUpper lobectomyMediastinal exposureThoracoscopySurgical exposure (low priority)Middle and lower lobectomies and subsegmental resectionsEsophageal surgeryThoracic spine procedureMinimal invasive cardiac surgery (MID-CABG, TMR)Postcardiopulmonary bypass status after removal of totally occluding chronic unilateral pulmonary emboliSevere hypoxemia due to unilateral lung disease
6 Physiology of the LDPUpright position LDP, lateral decubitus position
8 Shunt and OLV Physiological (postpulmonary) shunt About 2-5% CO,Accounting for normal A-aD02, mmHgIncluding drainages fromThebesian veins of the heartThe pulmonary bronchial veinsMediastinal and pleural veinsTranspulmonary shunt increased due to continued perfusion of the atelectatic lung and A-aD02 may increase
10 OLV and shunt fraction with and without anesthesia
11 Physiology of OLVProtective influences in response to the obligatory pulmonary shunt includes the hypoxic pulmonary vasoconstriction, 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.
12 HPVThe mechanism of HPV is not completely understood. Vasoactive substances released by hypoxia or hypoxia itself (K+ channel) cause pulmonary artery smooth muscle contractionHPV 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
13 Factors Affecting Regional HPV HPV is inhibited by: volatile anesthetics (not N20),vasodilators (NTG, SNP, dobutamine, many ß2-agonist),increased PVR and hypocapniaPEEP,vasoconstrictor drugs (preferentially constrict normoxic lung vessels)
14 Methods of OLV Double-lumen endotracheal tube (DLT) Single-lumen ET with a built-in bronchial blocker, Univent TubeSingle-lumen ET with an isolated bronchial blockerArndt (wire-guided) endobronchial blocker setBalloon-tipped luminal cathetersEndobronchial intubation with a single-lumen ET
15 DLTType:Carlens, a left-sided + a carinal hookWhite, a right-sided Carlens tubeBryce-Smith, no hook but a slotted cuff/RtRobertshaw, most widely usedAll have two lumina/cuffs, one terminating in the trachea and the other in the mainstem bronchusRight-sided or left-sided availableAvailable size: 41,39, 37, 35,32, 28,26 French (ID=,10.0,9.5,9.0, 8.5, 8.0, 7.0 and 6.5 mm respectively)
17 Schematic diagram depicting passage of the left-sided double-lumen endotracheal tube in a supine patient.A, The tube is held with the distal curvature concave anteriorly and the proximal curve concave to the right and in aplane parallel to the floor. The tube is then inserted through the vocal cords until the bronchial cuff passes the vocalcords. The stylet is then removed. B, The tube is rotated 90 degrees counterclockwise so that the distal curvature isconcave anteriorly and the proximal curvature is concave to the left and in a plane parallel to the floor. C, The tube isinserted until either mild resistance to further passage is encountered or the end of the common molding of the twolumens is at the teeth. Both cuffs are then inflated, and both lungs are ventilated. Finally, one side is clamped while theother side is ventilated and vice versa
18 Method of insertion Blind technique Caution: DLT should pass without any resistanceOptimal depth of insertion for a left sided DLT is ~ patients height ~ 12 +(patients height/10) cmDirect vision technique:uses fiberoptic bronchoscope,however both methods results in successful placement in approx equal number of patients
19 Confirming position of DLT Alternately blocking the tracheal and bronchial lumen and checking for the air entry.With the help of fiberoptic bronchoscopyChest –x ray
21 Selection of DLT based on adult patient sex and height Height(cm)Size(Fr)Female<160 (63 inches)35>16037Male<170 (67 inches)39>17041
22 Right sided DLT Margin of safety is low : 1. Rt. Upper lobe bronchus is short2. Rt. u/l bronchus originates at a distance of cm from the carinaFewer indicationsDoughnut shaped cuffAdditional opening for the ventilation of right upper lobe.
23 Indications for a right sided DLT Distorted anatomy of the entrance of a left main stem bronchusExternal or intraluminal tumaour compressionDescending thoracic artery aneurysmSite of surgery involving the left main stem bronchusLeft lung transplantationLeft sided tracheobronchial disruptionLeft sided pneumonectomyLeft sided sleeve resection
24 Left DLT Most commonly used The bronchial lumen is longer, and a simple round opening and symmetric cuff.Better margin of safety than Rt DLTCan be usedLeft lung isolation:clamp bronchial +ventilate/ tracheal lumenRight lung isolation:clamp tracheal +ventilate/bronchial lumen
25 Univent Tube... Developed by Dr. Inoue Movable blocker shaft in external lumen of a single- lumen ET tubeEasier to insert and properly position than DLT (diff airway, C-s injury, pedi or critical pts)No need to change the tube for postop ventilationSelective blockade of some lobes of the lungSuction and delivery CPAP to the blocked lung
26 Arndt Endobronchial Blocker set Invented by Dr. Arndt, an anesthesiologistIdeal for diff intubation, pre-existing ETT and postop ventilation neededRequires ETT > or = 8.0 mmSimilar problems as UniventInability to suction or ventilate the blocked lung
27 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-consumingInability to suction or ventilate the blocked lungEndobronchial intubation of single-lumen ETTThe easiest and quickest way of separating one lung from the other bleeding one, esp. from left lungMore often used for pedi patientsMore likely to cause serious hypoxemia or severe bronchial damage
28 Comparision of lung isolationtechniques OPTIONSADVANTAGESDISADVANTAGESDouble lumen tubeDirect laryngoscopyVia tube exchangerFibre opticallyQuickest to place successfullyReposition rarely requiredBronchoscopy to isolated lungSuction to isolated lungCPAP easily addedCan alternate OLV to either lung easilyPlacement possible without bronchoscopySize selection more difficultDifficult to place in difficult or in abnormal tracheaNot optimal for postop ventilationPotential laryngeal traumaPotential bronchial traumaBonchial blockerArndtCohenfugiSize selection rarely an issueEasily added to regular ETTAllows ventilation during placementEasier placement in DA and childrenPostoperative two-lung ventilation easySelective lobar lung isolation possibleCPAP to isolated lung possibleMore time neededRepositioning needed more oftenBronchoscope essentialnonoptimal Rt lung isolationBronchoscopy to isolated lung impossibleMinimal suction to isolated lungDifficult to alternate OLV to either lung
29 OptionsAdvantagesDisadvantagesUnivent tubeSame as BBsLess repositioning compared with BBsETT portion has higher airflow resistance than regular ETTETT portion has larger diameter than regular ETTEndobronchial tubeLike regular ETTs , easier placement in patients with DALonger than regular ETTShort cuff designed for lung isolationBronchoscopy neseccary or placementDoes nat allow for bronchoscopy, suctioning or CPAP to isolated lungDifficult right lung OLVEndotracheal tube (ETT) advanced into bronchusEasier placement in patients with difficult airwaysDoes not allow for bronchoscopy , suctioning or CPAP to isolated lungCuff not designed for isolated lungExtremely difficult right OLV
30 Difficult airway and OLV 5%-8% of patients with primary lung carcinoma have a carcinoma of the pharynx as wellMany of these patients have previous radiation exposure or previous surgery done.They might have distorted anatomy at or beyond carina. eg…descending thoracic aortic aneurysm, intraluminal or extraluminal tumourCan be detected by chest-x ray and CT scan
31 Approach to difficult airway A flexible fiberoptic bronchoscopy is essentialPrimary goal is to establish an airway with the help of a SLT (awake or anesthetised) f/b the insertion of bronchial blockers.An alternative is to insert a SLT and then insert DLT with the help of a tube exchanger
32 In a tracheostomised patient Insertion of a SLT f/b an independent bronchial blockerUse of a disposable cuffed tracheostomy cannula with an independent bb passed coaxiallyReplacement of the tracheostomy canula with a short DLT such as NARUKE DLTPlacement of a small DLT through tracheostomy stomaOral access to the airway for standard placement of a DLT or blocker
40 Assessment of respiratory functions continued…………… Lung parenchymal testsABG parameter : PaO2 < 60mm HgPaCO2 >45 mmHg( warning indicator of increased risk, however resections are done with these figures nowadays)Most useful test : DLCOppo DLco can be calculated like ppo FEV1ppo DLco < 40 % increases respiratory and cardiac complicationsPREOP. FEV1 OR DLco < 20% Is UNACCEPTABLE and is the absolute MINIMAL value required. ( national emphysema treatment trial )
41 Assessment of respiratory functions continues……… cardiopulmonary interactions (most important assessment of respiratory function)Laboratory exercise testingGold standardVo2 max (maximum oxygen consumption) is the most useful predictor of post operative outcome.Vo2 max < 15 ml/kg/min is unacceptableVo2 max >20 ml/kg/min has fewer complicationEXPENSIVEStair climbing tests5 flights of stairs ~ V02 max >20 ml/kg/min2 fight of stairs ~ Vo2 max ~ 12 ml/kg/min -- very high risk(climbing should be at patients own pace without stopping,1 flight of stairs = 20 steps withs each step of 6 inches )
42 Assessment of repiratory functions continues…………… Six minute walk test(6MWT)< 610 m/ 2000 ft Vo2 max< 15 ml/kg/min~fall in SpO2 > 4% during exercise( increased morbidity and mortality)ppo V02 max< 10 ml/kg/min is an absolute contraindicationmortality rate is approximately 100%V-P scintigraphyShould be considerd for any patient of pneumonenctomy having a preop FEV1 &/or Dlco <80%performed at rest while FEV1 is a forced maneuver
43 Assessment of repiratory functions continued…………… Split lung function testThese tests have not shown sufficient predictive value or validity for universal adoption and are hence not recommended any longerReplaced by spirometry/ DLco/ exercise tolerance & V/Q scaning.
44 The three legged stool of pre thoracotomy respiratory assessment Respiratory mechanicsFEV1(ppo>40%)MVV, RV/TLC, FVCCardiopulmonary reserveVo2 max >15ml/kg/minStair climbing>2 flight6MWT>610m/2000ftExercise SpO2 < 4 %Lung parenchymal functionDlco (ppo >40%)PaO2 >60PaCO2 <45
45 Concomitant medical conditions cardiovascularIschemia : intermediate risk surgery5% incidence post thoracotomypeaks on 2 and 3rd post op dayACC/AHA guidelines to be followedArrhythmiasRight ventricular dysfunctionRenal dysfunctionPerioperative mortality is 19% in pt. developing deranged KFT in periop. Period as against 0% in those having normal KFTIncreased risk in pt. having h/o renal impairmentuse of diureticuse of NSAIDSHence I/op fluid management and intensive perioperative fluid management is essentialAgeRate of respiratory complication doubles(40%) and cardiac complications (40%) triples in elderly
46 Concomitant medical conditions continues……. Problems in a COPD patientRespiratory drive,CO2 retainers,Increased role of HPVNocturnal hpoxemia because of rapid shallow breathing in a REM sleepRight ventricular dysfunctionBullaeFlow limitation :stage I :FEV!>50% no significant dyspnoea ,hypoxemia or hypercapniaStage III :FEV1 <35% --life expectancy <3 years post thoracotomy
47 Beneficial effects of smoking cessation and time course 12–24 hrDecreased CO and nicotine levels48–72 hrCOHb levels normalized, ciliary function improves1–2 wkDecreased sputum production4–6 wkPFTs improve6–8 wkImmune function and metabolism normalizes8–12 wkDecreased overall postoperative morbidity and mortality
48 Anesthetic considerations in lung cancer patients (“the 4 Ms” ) Mass effectsObstructive pneumonia,lung abscess, superior vena cava syndrome, tracheobronchial distortion , pancoast syndrome, recurrent laryngeal nerve or phrenic nerve palsy, chest wall or mediastinal extensionMetabolic effectLambert – Eaton syndrome, hypercalcemia, hyponatremia, cushing syndromeMetastasesParticularly to brain, bone , liver and adrenalMedicationsChemotherapy agents , pulmonary toxicity ( bleomycin,mitomycin C), cardiac toxicity(doxorubicin), renal toxicity ( cisplatin )
50 To discuss post op analgesia the risks and benefits of the various forms of post-thoracotomy analgesia should be explained to the patientPotential contraindications such as coagulation problems, sepsis, or neurologic disorders should be determinedAmerican Society of Regional Anesthesia (ASRA)an interval of 2 to 4 hours before or 1 hour after catheter placement for prophylactic heparin administration.an interval of 12 to 24 hours before and 24 hours after catheter placement is recommended for LMWH
51 Think about post thoracotomy anesthetic management (based on ppo FEV1%) >40%Extubate in the ORPatient AWaC (alert ,warm and comfortable)30-40%Extubation on the basis ofExercise tolerance,Dlco,V/Q scan, associated diseases<30%Staged weaningConsider extubation if >20% + thoracic epidural analgesia
52 Summarise preoperative assesment Initial assessmentFinal assessmentCOPD patients : ABG, physiotherapy , bronchodilatorsAssess exercise tolerance,estimate ppo FEV1, discuss post op. analgesia, discontinue smokingPatients with ppo FEV1<40%:Dlco,V/Q scan,Vo2 maxCancer patient: consider 4MsIncreased renal risk : measure creatinine and BUNReview initial assessment and test results.Assess difficulty of lung isolation: chest Xray and CT scan.Assess risk of hypoxemia during one lung ventilation
53 Increased risk of hypoxemia High percentage of ventilation or perfusion to the operative lung preoperativelyPoor PaO2 during two-lung ventilation particularly in the lateral position intraoperativelyRight sided thoracotomyNormal preoperative spirometry or restrictive lung diseaseSupine position during OLV
54 Premedicationavoid inadvertent withdrawal of those drugs that are taken for concurrent medical conditionsFor surgeries like oesophageal reflux surgeries aspiration prophylaxis are routinely ordered preoperativelydo not routinely order preoperative sedation or analgesia for pulmonary resection patientsMild sedation short-acting benzodiazepine is often given immediately before placement of invasive monitoring lines and catheters.an antisialagogue (e.g., glycopyrrolate) is useful to facilitate fiberoptic bronchoscopyIt is a common practice to use short-term intravenous antibacterial prophylaxis
55 Intraoperative monitoring Oxygenation :significant desaturation( SpO2<90%) occurs in 1-10% of patients inspite of high FiO2 (1.0).PaO2 offers a better margin of safety then SpO2Decreased initial PaO2 and rapid fall in PaO2 after initiation of OLV is a good indicator of subsequent desaturation.Useful to measure PaO2 before and 20 minutes after OLVCapnometryLess reliable then PaCO2PaCO2-EtCO2 gradient increasedOther components of minimum mandatory monitoring : BP,ECG,temperature
56 Invasive monitoringArterial line:Surgical compression of heart & great vessels l/t hypotensionCVP : non reliable , useful postoperativelyPulmonary artery catheters: less reliable for OLVunsurety about the location of the tipsignficant u/l differences in lung perfusion.complicationsContinuous spirometry monitoring of inspired and expired volume auto-PEEPaids in assessing and managing pulmonary air leak during pulmonary resectionTransesophageal echocardiography :continuous real time monitoring ofmyocardial function and preloadPotential indication: hemodynamic instability,pericardial effusion,cardiac involvement by tumour,air emboli,pulmonary thromboendarterectomy, thoracic trauma,lung transplantation.Difficult in pt. having esophageal pathology,
57 Conditions during thoracotomy in the lateral decubitus position when pulmonary artery (PA) catheter datamay be inaccurate.
58 PositioningThe majority of thoracic procedures are performed with the patient in the lateral positionmonitors will be placed and anesthesia will usually be induced with the patient in the supine positionhypotension on turning the patient to or from the lateral positionAll lines and monitors will have to be secured during position change and their function reassessed after repositioninganesthesiologist should take responsibility for the head, neck, and airway during position changeEndobronchial tube/blocker position and the adequacy of ventilation must be rechecked by auscultation and fiberoptic bronchoscopy after patient repositioning.
59 “Head-to-toe” survey for neurovascular injury after position change 1. Dependent eye 2. Dependent ear pinna 3. Cervical spine in line with thoracic spine 4. Dependent arm: a. Brachial plexus b. Circulation 5. Nondependent arm : a. Brachial plexus b. Circulation
60 Factors Contributing to Brachial Plexus Injury in the Lateral Position Dependent Arm (Compression Injuries) Arm directly under thorax Pressure on clavicle into retroclavicular space Cervical rib Caudal migration of thorax padding into the axilla Nondependent Arm (Stretch Injuries)Lateral flexion of cervical spine Excessive abduction of arm (>90%) Semiprone or semisupine repositioning after arm fixed to a support
61 Anesthetic management Fluid Management for Pulmonary Resection Surgery 1. Total positive fluid balance in the first 24-hour perioperative period should not exceed 20 mL/kg. 2. For an average adult patient, crystalloid administration should be limited to < 3 L in the first 24 hours. 3. There should be no fluid administration for third space fluid losses during pulmonary resection. 4. Urine output > 0.5 mL/kg/hr is unnecessary. 5. If increased tissue perfusion is needed postoperatively, it is preferable to use invasive monitoring and inotropes rather than to cause fluid overload.
62 Use of nitrous oxideuse of N2O/O2 mixtures is associated with a higher incidence of post-thoracotomy radiographic atelectasis (51%) in the dependent lung than when air/oxygen mixtures are used (24%).also tends to increase pulmonary artery pressures in patients who have pulmonary hypertensionN2O inhibits HPVN2O is contraindicated in patients with blebs or bullaeN2O is usually avoided during thoracic anesthesia
63 Temperatureheat loss from the open hemithoraxMost of the body's physiologic functions, including HPV, are inhibited during hypothermiaparticularly a problem at the extremes of the age spectrum.Increasing the ambient room temperature, fluid warmers, and the use of lower- or upper-body forced-air patient warmers (or both)
64 Cardiovascular and Respiratory goals anesthetic technique should optimize the myocardial oxygen supply/demandThoracic epidural anesthesia/analgesia is recommendedhigh incidence of coexisting reactive airway disease, added airway manipulation by the DLT or bronchial blockerThus, need anesthetic technique that decreases bronchial irritability, causes bronchodilation, and avoids release of histamineFor intravenous induction of anesthesia either propofol or ketamine, & for maintenance of anesthesia, propofol and/or any of the volatile anesthetics are recommended
65 Choice of AnestheticAll of the volatile anesthetics inhibit HPV in a dose-dependent fashion :halothane > enflurane > isofluraneIn doses less than or equal to 1 MAC, the modern volatile anesthetics depress HPV minimallyHence TIVA has no proven benefit against 1 MAC inhalational anesthesia
66 Suggested ventilatory parameters for OLV Guidelines/ ExceptionsTidal volume5-6 mL/kgMaintain:Peak airway pressure < 35 cm H2OPlateau airway pressure < 25 cm H2OPositive end-expiratory pressure5 cm H2OPatients with COPD: no added PEEPRespiratory rate12 breaths/minMaintain normal Paco2; Pa-ETco2 will usually increase 1-3 mm Hg during OLVModeVolume or pressure controlledPressure control for patients at risk of lung injury (e.g., bullae, pneumonectomy, post lung transplantation)
67 Therapies for Desaturation during One-Lung Ventilation Severe or precipitous desaturation: Resume two-lung ventilation (if possible).Gradual desaturation: 1. Ensure that delivered Fio2 is 1.0. 2. Check position of double-lumen tube or blocker with fiberoptic bronchoscopy. 3. Ensure that cardiac output is optimal; decrease volatile anesthetics to < 1 MAC. 4. Apply a recruitment maneuver to the ventilated lung (this will transiently make the hypoxemia worse). 5. Apply PEEP 5 cm H2O to the ventilated lung (except in patients with emphysema). 6. Apply CPAP 1-2 cm H2O to the nonventilated lung (apply a recruitment maneuver to this lung immediately before CPAP). 7. Intermittent reinflation of the nonventilated lung 8. Partial ventilation techniques of the nonventilated lung: a. Oxygen insufflation b. High-frequency ventilation c. Lobar collapse (using a bronchial blocker) 9. Mechanical restriction of the blood flow to the nonventilated lung
68 Post operative complications Early major Respiratory failurecardiac herniationtorsion of a remaining lobe after lobectomydehiscence of a bronchial stumphemorrhage from a major vesselWhere
69 Post operative respiratory failure leading cause of postoperative morbidity and mortalityAcute respiratory failure after lung resection is defined as:acute onset of hypoxemia (Pao2 < 60 mm Hg) or hypercapnia (Paco2 > 45 mm Hguse of postoperative mechanical ventilation for more than 24 hoursreintubation for controlled ventilation after extubationincidence of respiratory failure after lung resection is between 2% and 18%
70 To minimise pulmonary complications postoperatively thoracic epidural analgesia :prevention of atelectasis and secondary infectionsbetter preservation of the functional residual volumeefficient mucociliary clearancealleviation of the inhibiting reflexes acting on the diaphragmChest physiotherapy, incentive spirometry, and early ambulation are crucialprovide better oxygenation, treat infection, and provide vital organ support without further damaging the lungs.
71 multiple sensory afferents : Post operative analgesiamultiple sensory afferents :incision (intercostal nerves T4-T6),chest drains (intercostal nerves T7-T8),mediastinal pleura (vagus nerve, CN X),central diaphragmatic pleura (phrenic nerve, C3-C5),ipsilateral shoulder (brachial plexus).Hence there is no one analgesic technique that can block all these various pain afferents, so analgesia should be multimodal.The ideal post-thoracotomy analgesic technique will include three classes of drugs: opioids, anti-inflammatory agents, and local anesthetics.
72 Post op analgesia continues… Systemic Analgesia:Opioids:effective in controlling background pain but the acute pain component associated with cough or movement requires plasma levels that produce sedation and hypoventilationNSAIDS :reduce opioid consumption more than 30%.particularly useful treating the ipsilateral shoulder painKetamine: less respiratory deppressionDexmedetomidine: described as an useful adjunctLocal Anesthetics/Nerve Blocks:Intercostal nerve blocksInterpleural blocksEpidural analgesia