Anesthesia for Thoracic Surgery – Flashcards
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What are indications for Thoracic Surgery
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Tumor Infection Lung lavage Lung reduction surgery Vascular surgery Cardiac surgery Spine surgery
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What is the most common position is used for a thoracotomy?
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lateral decubitus
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what should you monitor for thoracic surgery patients?
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sudden and severe changes in ventilation & hemodynamics that accompany positioning, one lung ventilation and surgical manipulation of airway & thoracic stuctures
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what leads should be monitored for ischemia ?
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lead II and V5 detect 85% of ischemia
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what are the anesthetic considerations in lung cancer patients
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the 4 "M"s mass effects metabolic effects metastases medication
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what are the mass effects
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obstructive pneumonia, lung abscess, superior vena cava syndrome, tracheobroncial distortion, Pancoast syndrome, recurrent laryngeal nerve or phrenic nerve paresis, chest wall or mediastinal extension
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what are the metabolic effects
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Lambert-Eaton syndrome, hypercalcemia, hyponatremia, Cushing syndrome
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what are the metastases effects
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particularly to brain, bone, liver, and adrenals
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what are the medication effects
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chemotherapy-induced lung changes
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PREOP factors that predict post op complications of low-risk patients
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FEV1 > 2L OR 80% predicted PPO FEV1 as least 80% of predicted normal valve VO2 max > 20mL/kg/min ability to climb 5 flights of stairs
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PREOP factors predict post op complications of high risk patients
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FEV1 < 2L or <40% of predicted PPO FEV1 < 40% of predicted normal volume DLCO (diffusing capacity for carbon monoxide) <40% of predicted predicted post op product <1650 VO2 max 4% during exercise
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what are the endocrine like substances secreted by tumors?
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adrenocorticotropic hormone, antidiuretic hormone, serotonin, parathyroid hormones and insulin
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what nutritional status places cancer patients at increased risk for pneumonia?
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hypoalbuminemia and malnutrition
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how do you calculate PPO FEV1
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multiplying the current FEV1 by the fraction of functioning lung OR the fraction of lung segments that will remain after surgery
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for thoracotmies an arterial line should be placed in what arm?
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the dependent arm
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for mediastinoscopy, where should the arterial line be placed
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in the right arm .. this can detect compression of the innominate artery and help prevent a decrease in cerebral blood flow alternately ..pulse ox on right arm and left aline can also be used
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if a subclavian CVP line is to be placed, on which side should it be placed?
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the same side as the planned thoracotomy
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An awake lateral decubitus patient receives most of the tidal ventilation to what lung?
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dependent lung
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An anesthetized lateral decubitus patient receives most of the tidal ventilation to what lung?
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non-dependent lung
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what is the cause of reduced FRC in the lateral decub position in the anesthetized patient
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the weight of the mediastinum and the cephalad displace of the diagram by ABD contents
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what setting can be added to mechanical ventilation to improve V/Q ratio and restore FRC?
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PEEP
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Ventilation is increased or decreased to the dependent lung in an anesthetized open chest patient?
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decreased
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open chest greatly _______ resistance to gas flow in the non dependent lung by detaching the lung from its pleural connection with the chest wall
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reduces
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what is paradoxical respiration?
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The deflation of the lung during inspiration and inflation during expiration.
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What diminishes the effects of mediastinal shift and paradoxical respiration?
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positive pressure ventilation although open chest provides no resistance and greatly increased compliance of that lung allows a higher proportion of ventilation to go to the nondependent lung
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Indications for OLV : Absolute
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1. Isolate 1 lung to avoid contamination from the other infection massive hemorrhage 2. Control distribution of ventilation bronchopleural fistula bronchopleural cutaneous fistula surgical opening of a major conducting airway giant unilateral lung cyst or bulla tracheobronchial tree disruption life-threatening hypoxemia r/t unilateral lung disease 3. Unilateral bronchopulmonary lavage pulmonary alveolar proteinosis
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Indications for OLV : Relative
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1. Surgical exposure (high priority) thoracic aortic aneurysm pneumonectomy thoracoscopy upper lobectomy mediastinal exposure 2. Surgical exposure (lower priority) middle& lower lobectomies & subsegmental resection esophageal resection procedures on the thoracic spine 3. Pulmonary edema after removal of PE 4. Severe hypoxemia d/t unilateral lung disease
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DLT advantages
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Allows one-lung ventilation
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DLT disadvantages
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Blocks whole lung Trauma from large OD Hard to place Increased aspiration risk Need to exchange
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Bronchial Blocker advantages
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Selective lobe blockade Easier to place if difficult airway or existing ETT
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Bronchial Blocker disadvantages
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Inability to suction blocked lung Can slip and block trachea More difficult to place Easily dislodged if deflated
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what size DLT is for males
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39F - 41F
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what size DLT for females
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35F-37F
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what is the distance from the carinal bifurcation to the beginning of the right upper lobe?
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2.5 cm or less
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what is the distance from the carinal bifurcation to the beginning of the left main bronchus?
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4-5 cm
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what are contraindications to a DLT?
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1. internal lesions of the trachea or main bronchi 2. compression of the trachea or main bronchi by an external mass 3. presence of descending thoracic aortic aneurysm which can compress or erode the left main bronchusopy 4. difficult airway which direct laryngosc
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due to increase time to place and verify placement of a DLT increases the risk of what?
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aspiration
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If a patient has small anatomy and can not accommodate a large DLT what can be done?
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use a single lumen tube with intention with intentional endobronchial intubation
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what is the risk of right sided ventilation with a single lumen ETT with intentional endobronchial intubation?
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occlusion of right upper lobe
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what is another strategy to ventilate a pediatric patient undergoing lung surgery?
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jet ventilation : combination of pneumothorax & low mean airway pressures generated by jet ventilation should allow adequate deflation of operative lung
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how is a DLT placed?
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1. direct laryngoscopy with mac blade for better clearance of the tube 2. advance with distal curve concave anteriorly until vocal cords passed 3. may remove stylet, rotate 90 degrees toward the bronchus to be intubated
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DLT should be advanced to what depth for females? males??
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females: 27cm or until resistance is met males : 29cm
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tracheal cuffs requires how much air? bronchial cuff requires how much air?
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tracheal cuff 5-10mL bronchial cuff 1-2mL
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T/F the bronchial tube holds large volume/low pressure
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FALSITO bronchial tube holds a small volume and produce high pressure on endobronchial mucosa and should be deflated during the procedure once OLV is NO LONGER NEEDED
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how is placement and verification of DLT done?
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Flexible Fiberoptic bronchoscopy auscultation is not highly reliable method
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what are the advantages of fiberoptic inspection of the DLT?
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1. guidance during initial placement 2. ability to visualize correct depth of the bronchial cuff 3.visualization of proper positioning of the right upper lobe port(if present)
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should the patient be check with bronchoscopy after positioned lateral?
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YES - DLT will commonly withdraw from the bronchus by 1 cm
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what do you want to see with fiberoptic bronchoscopy tracheal verification
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Carina Right lung bronchi DLT in left bronchus No cuff herniation
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what do you want to see with fiberoptic bronchoscopy endobronchial verification
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Left lung bronchi
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complications of DLT ?
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1. Trauma : Vocal cords, Bronchial rupture 2. Hypoxemia d/t malposition 3. Rupture thoracic aneurysm 4. Barotrauma 5. Loss of carinal hook
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When the LEFT lung is the non-dependent lung what is the distribution of blood flow BTN the non-dependent and dependent lungs?
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35% left 65% right
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When the RIGHT lung is the non-dependent lung what is the distribution of blood flow BTN the non-dependent and dependent lungs?
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45% right 55% left
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What is AVERAGE OLV blood flow distribution of non-dependent to dependent ratio
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40%:60%
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What is hypoxic pulmonary vasoconstriction (HPV)?
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a compensatory mechanism of increasing vascular resistance in hypoxic areas of the lungs and this diverts some blood flow to areas of better ventilation and oxygenation
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how is vasoconstriction caused in HPV?
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hypoxia reduces AOS (activated oxygen species) that act as a 2nd messenger from the oxygen sensors and reduction of their out flow leads to inhibition of voltage dependent potassium channel... result is influx of calcium and vasoconstricion.
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what is trigger of HPV?
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alveolar hypoxia NOT arterial hypoxia
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what can inhibit the HPV mechanism?
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calcium channel blockers (verapamil, volatile gases) vasodilators (nitrates) augmented by chemoreceptor agonist (almitrine)
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Cardiac output to the non-ventilated lung is decreased by what percent during OLV ?
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20-25%
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what is the percentage of hypoxic lung will HPV be effective?
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20-80% -80%-causes increased PVR which increase right heart workload and strain
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what are the factors that reduce effectiveness of HPV?
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1. shunt fraction 80% 2. hypervolemia or high cardiac output 3. hypovolemia may trigger adrenergic vasoconstriction 4. excessive TV or PEEP 5. hypocapnia 6. acidosis/alkalosis 7. hypothermia causes pulmonary vasoconstriction 8. volatile agents 9. >1.5 MAC 10. vasoactive medications
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When ventilating during OLV what TV and PEEP should be used?
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TV 6mL/kg and excessive PEEP should be avoided
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what are the benefits of inhalation agents during OLV?
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1. allow the use of high FiO2 2. produce bronchodilatory effects 3. decrease airway irritability in pts subject to direct manipulation of lung tissue 4. rapid elimination of inhalation agents
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what is the anesthetic management for a thoracic surgery patient/OLV?
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1. Maintain normovolemia 2. Inhaled agents <1.5 MAC 3. Avoid N2O (increases PVR/mitral valve stenosis/RV dysfunction) pt with emphysema/bulle 4. ABGs as needed 5. Air-O2 mix to maintain adequate PaO2 6. Minimize narcotics 7. Goal is to extubate patient
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Is postop residual curarization common?
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yes after intermediate and long-acting NMBA are used especially long acting
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what is the role of regional anesthesia?
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for post op pain management reducing atelectasis, pneumonia, resp failure, & other pulmonary complications
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what are physiologic causes of decrease PaO2 during OLV
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1.bronchospam 2. decrease cardiac output 3. hypoventilation 4. low FiO2 5. pneumothorax of dependent lung 6. DLT malpositioning
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what are the interventions that can improve PaO2?
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CPAP to the non-dependent lung (100% efficacious in increasing PaO2) moderate amount of PEEP combination of both CPAP&PEEP
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what should your do if hypoxia happens during OLV?
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1. Verify DLT position 2. Low level CPAP to non-dependent lung 3. Intermittent inflation of non-dependent lung 4. PEEP to dependent lung 5.Vary ventilation (Pressure control/Jet ventilation)
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what is involved in re-inflation of the operative lung
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1. surgeon checking for air leaks by inflating lung with large TV 2. inflate with slow breaths 3. may require high PIP (30-40cm H2O) 4. observe re-inflation deflate the bronchial cuff after re-expansion
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what are some post op pain management for thoracic surgeries?
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1. Thoracic epidural T6-T8 placed preop 2. use of NMDA blocker (ketamine) 3. Intercostal (paravertebral) nerve blocks 4. Pleural catheter 5. cryoanalgesia
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what does post op thoracic pain cause?
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splinting decrease in resp effort hypoxemia resp acidosis can lead to pneumonia and atelectasis
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what are some post op complications?
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1. ALI 2. Low cardiac output Hemorrhage, Hypovolemia, Right HF, Dysrhythmias, Heart herniation thru pericardial defect 3. Bronchopleural fistula 4. Thoracic duct injury (left side) 5. Nerve injury Phrenic, Recurrent laryngeal, Spinal cord
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significant factors associated with ALI are
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right pneumonectomy, overhydration (more than 2.6 mL/kg/hr), high airway pressures during OLV, preop ETOH abuse female, poor predicted post op pulm function, trauma, infection, chemotherapy, MS lymphatic damage, blood transfusion/FFP, serum cytokines, O2 toxicity, prolonged OLV >100 mins, increased postop urine output
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what are risk reduction strategies for occurrence of ALI
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1. withdrawal of ETOH for a safe period 2. correction of nutritional deficits 3. intra op use of pressure control ventilation with small TV 4. use of O2-air mixtures to prevent barotrauma, volutrauma, oxidative damage 5. limit of fluid intake for first 24-48 hrs post op 6. tight control of hemodynamics (PA cath) 7. early detection of pulm HTN & lung edema
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why would you have dysrhythmias?
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hypoxemia vagal irritation atrial inflammation preexisting cardiac disease pulm HTN right atrial or ventricular dilation
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early post op resp complications
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atelectasis pneumonia resp failure bronchopleural or bronchocutaneous fistula pneumothorax torsion of remaining lobes necessitating surgical correction pulm edema
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indication for mediastinoscopy
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Mediastinal mass Biopsy Lymph node resection Cyst removal Esophagectomy
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what are complications of mediastinoscopy
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Major hemorrhage Stroke Air embolism Pneumothorax Reflex arrhythmias Phrenic nerve paralysis Recurrent laryngeal nerve palsy Oesophageal tear Tracheobronchial laceration Thoracic duct injury Minor bleeding
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what is superior vena cava syndrome?
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venous engorgement of the upper body caused by compression of the superior vena cava by a mass
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what issues with mediastinal masses
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1. Tracheobronchial obstruction Worse with induction of anesthesia & PPV 2. Superior vena cava syndrome Engorged vessels in airway and face Maintain head up 20 degrees 3. Systemic effects of tumor secretions Myasthenia gravis Eaton-Lambert syndrome Altered hormone production (ACTH, ADH, PTH)
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Anesthetic Management of mediastinoscopy
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1. 2 large bore IV's (poss. Lower extremity) 2. T&X 3. A-line or pulse ox on right 4. Standard induction if asymptomtomatic 5. If obstruction: Minimize/avoid preop sedation Awake fiberoptic or inhalation induction Maintain spontaneous ventilation Surgeon can place rigid bronchoscope
