Thoracic Surgery

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cmatthews
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259669
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Thoracic Surgery
Updated:
2014-02-05 18:10:11
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BC CRNA Thoracic Surgery
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Thoracic Surgery Cards from Denise's lecture
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  1. __-____of lung cancer occurs in smokers.
    90-100%  According to literature, 90% of pt w/lung cancer will admit to being smokers but there is some thought that the other 10% are passive smokers and don’t consider themselves smokers.
  2. TRUE or FALSE. 1ppd for 20years has same lung disease as the 2ppd for 10years.
    TRUE
  3. What is pack years directly related to?
    Pack years smoked is directly related to gas flow and closing capacity. So these patients are prone to post-op atelectasis and hypoxemia.
  4. How is smoking related to closing capacity?
    Emphysema, less recoil and low pressure inside alveoli. Pressure on the outside is higher than the pressure on the inside of the alveoli so you get collapse (at a lower volume).  They have a higher propensity to close and close at a higher volume. But they're lung volume is much higher (they have air trapping)
  5. What is severe exertional dyspnea?
    • Can’t walk comfy in flat.
    • Severe exertional dyspnea  is less than 1500ml.  
    • (normal is 4L, 80% of vital capacity which is 5L) if pt has FEV1 of only 1500ml the patient will likely need post-op ventilation. 
  6. Which is pink puffer and which is blue bloater?
    • Pink puffer: emphysema
    • Blue bloater: bronchitis
  7. Describe the ABG of a blue bloater? What is their respiratory drive?
    • So hypoxic and elevated CO2. They have hypoventilation and CO2 retention.
    • They have become insensitive to CO2 and our anesthetics decrease sensitivity to CO2.
    • They’re drive is hypoxia not CO2. Those receptors are in the carotid and aortic bodies. These patients are hypoxic and hypercarbic. Because of hypoxic drive. They don’t do well if we give them O2
  8. Vital capacity less than __% of predicted or less than __L is at increased risk
    50%; 2L
  9. These patients with poor PFTs have a ___% risk of complications and ___% risk of post-op mortality.
    33%; 10%
  10. Why is having a low vital capacity such a problem during the post-op period?
    Low VC, they can’t cough effectively, takes a huge VC to have an effective cough. If no cough they can’t clear their secretions
  11. What two PFTs are very important?
    • Vital capacity and FEV1
    • Consider post-op ventilation if these are low
  12. PFTs are used in this patient population to assess lung resection. So if an FEV1 is less than ____ml that contraindicates lung resection.
    800ml
  13. PFTS w/COPD, looking for residual volume to total lung capacity ratio. Usual RV is __-__L. And usual TLC is approximately ___L so if this ratio is greater than ___% (which happens when there is a lot of gas trapping) then the patient is at high risk
    • RV: 1-1.5L
    • TCL: 6L
    • Greater than 50%
  14. If your patient has a low FEV1 in the pre-op area. What might you do???
    Give a bronchodilator and see if it improves
  15. What is the split lung test? What would show increased risk??
    • Split lung test: done to see the function of lung tissue that would remain after lung resection.
    • If the FEV1 is less than 850ml or if greater than 70% of blood flow will be going to the diseased lung then there is a huge increased risk.
    • V/Q scan, look at how much flow to each lung independently.
  16. What test would you do if the patient was having a pneumonectomy??
    • To mimic the post-op condition they could sometimes float a PA catheter and temporarily occlude the Pulmonary artery on the side lung that will be removed and assess what would the pressure be if that pulmonary artery no longer existed. Look at what the pulmonary pressure will be after.
    • Or put in the balloon and occlude the left or right main stem bronchus and see how the patient does. That would be done awake, occlude and see how the patient does
  17. Does restrictive lung disease has a high, normal, or low FEV1?
    HIGH
  18. What kind of variable obstruction happens with a mediastinal mass?
    • Extrathoracic obstruction.
    • Pressure on the mediastinum, it’s extrathoracic (outside the lungs) and it’s difficult to INHALE! The force of air coming out is lifting the mass but inhalation is very difficult.
    • On inspiration, as the pressure within the lung becomes more and more negative the positive pressure exerted by the mass collapses the airway. As we’re breathing in, w/normal spontenouas breathing, the lung pressure is becoming more and more negative, still have positive pressure from the mass and inhalation is compromised.
  19. What is the problem with restriction in the pulmonary vascular bed?
    • Once we have a restricted pulmonary vascular bed, the distensibility of the vascular bed is gone.
    •  In this situaiton as CO increases, PAp increases, this patient is non-compliant.(like in pneumonectomy, clot, or chornic hypoxemia which leads to pulonary HTN, as the CO increases, the PAp increases.
  20. We should have a pre-op EKG on each patient. When is the risk of MI greatest?
    During the operation and the 3rd post-op day
  21. If we have an abnormal EKG, what should we get next?
    • Stress test. If positive, move on to the ECHO.
    • And that’s abnormal if the CAD is severe, sometimes need to consider bypass grafting prior to pulmonary resection.
  22. What are our concerns for one lung ventilation? (for each lung)
    • One lung ventilation=SHUNT intra-op.
    • Also they’re having lung surgery and trauma to lung the surgeon is working on. Edema to operative lung.
    • The other lung, increases perfusion, increased pulmonary capillary pressure, could get dependent edema in that lung.
  23. Why is having an ART line so important for one lung anesthesia?
    • The shunt and A-a gradient!
    • So the Sat doesn’t tell us what the PO2 is. PO2 could be 400 or 150 (it’s the flat portion of the curve) but we want to know the degree of shunt.
    • EtCO2 doesn’t tell us the CO2 when there is dead space, CO2 to the right. The arterial CO2 could be VERY high, patient with a lot of dead space, lot of V/Q imbalance in COPD
  24. Which are more likely to have a problem with in one lung ventilation, PCO2 or PO2?
    CO2 diffuses easier (20x) than oxygen so a problem with PO2
  25. Failure to check equipment properly before induction of anesthesia is responsible for __% of critical incidents that occur during anesthesia
    22%
  26. What are the two reasons you would not have spontaneous breathing in a thoracotomy?
    Mediastinal shift and paradoxical breathing
  27. What is paradoxical breathing during an open thoractomy when the patient is spontaneously breathing?
    Inspriation: Air moves from the non-dependent to the dependent lung. So the dependent lung is getting air from trachea and the operative non-dependent lung. Air moving pardoxically because it’s going from non-dependent lung to dependent lung.

    Exhalation: positive pressure on exhalation. Some air moves from dependent lung back into trachea and some moves into the non-dependent lung because it’s open and compliant, there’s no resistance to flow there because the space is wide open.
  28. Why do we get more V/Q mismatch in the anesthetized patient (in lateral position)
    • In awake pt, usually the dependent lung takes in more volume with each breath (better compliance in the volume/pressure curve.
    • In anesthetized patient, lung volume and FRC are lower, both non-dependent and dependent lung are situated in different places on this curve. So now when the patient is anesthetized, the dependent lung is on a flatter part of the curve, the non-dependent lung gets more volume with each breath.
    • So you end up with more V/Q mismatch
  29. Two lung ventilation, simply because of gravity get more blood flow to dependent lung. (40% to non-dependent and 60% to dependent) if on 100% FiO2 the PaO2 is about 400 and the shunt under anesthesia is ___%.
    10%
  30. Two lung ventilation, simply because of gravity we get more blood flow to the dependent lung. What % to each lung??
    40% of blood flow to non-dependent and 60% to dependent
  31. What happens to the blood flow when we deflate one lung??
    The fractional blood flow has decreased to 22.5% (significant decrease) , d/t HPV, in situation of alveolar collapse, blood flow is diverted to open alveolar. So 77.5% of blood going to dependent. Now shunt fraction is 27.5%, expect PaO2 of about 150.
  32. What are the absolute indications for one lung anesthesia?
    • to prevent contamination of normal lung, spillage
    • Or a bronchopleural fistula (penetrating injury to the lung, injury to the broncho or pleural)
    • CF: unilateral lavage to clear the lung. If you’re going to lavage one lung, need to isolate the lung to prevent spillage.
  33. what are the cuff volumes in a DL tube?
    • Tracheal pilot balloon 5-10cc of air.
    • Bronchial pilot balloon (Max of 3cc of air)
  34. If intubating with a DL tube, do you use a MAC or Miller?
    MAC, more space
  35. What are the general sizes of DL tubes?
    Generally 35, 37 (women) and 39.
  36. Why do we prefer to use LEFT DL tubes instead of right (regardless of which lung we want to ventilate)?
    • The RIGHT upper lobe bronchus takes off very close to the carina. The distance to the carina and the take off of the right upper lobe is between 2-2.5cm (and on the left it is 5cm)
    • So if you didn’t take precautions and did a right sided tube, and the tube is right in front of the take off of the right upper lobe, so the right upper lobe is not ventilating.
    • So because this distance is so small there is an increased margin of safety for ventilating the LEFT upper lobe.
    • 5cm between carina and left upper lobe take off makes proper placement easier, left sided tubes are used more often.
  37. How and when should you check placement of the DL tube?
    • How: Clamp left (Bronchial) then hear breath sounds on right and not on the left. However the DEFINITVE way of checking the tube is fiberoptic. Usually tracheal port first, look to left and see the blue balloon off to the left and then put the scope through the bronchial side and see the take off to the left upper lobe.
    • When: initial placement and when the pt is lateral.
  38. What are the common malpositions of the DL tubes?
    • Too far in (only ventilating one lung)
    • Too far out (can't isolate one lung)
    • Tube went right when you wanted it to go left
  39. How do you manage one lung ventilation with a double lumen tube?
    Drop the lung volume 5-8ml/kg when ventilating one lung. Watch the pressures! Drop TV and keep PIP within normal range and stabilize the EtCO2 with the rate.
  40. What is another option to the DL tube for one lung ventilation?
    • Bronchial blocker. Regular ETT with a side slit and a stylet with a balloon at the end. A A uni-vent tube. Place like an ETT and do a fiberoptic (pedi size) and you steer w/ the stylet end, steer the cuff to where you want it. Isolate the right main stem or right lower lobe, isolate where you need it under direct vision.
    • Disadvantage: slips more easily. The bronchial cuff frequently needs to be repositioned. Also can’t suction one lung.
    • Advantages: easier to put in the tube to begin with and the tube doesn’t need to change at end of case.
  41. Why should we avoid high pressures when ventilating?
    • Big risk of acute lung injury (more than 8ml/kg) you would have an increase in vascular resistance.
    • Increase in vascular resistance, the vessels are no longer able to redirect flow away from hypoxic region. Extraalveolar are open but capillaries are closed from too much volume, limits the HPV response and worsens pulmonary hypertension.
  42. Due to shunt with one lung ventilation, on FiO2 of 100%, what is our PO2?
    150; we're near the slippery slope of the Oxygen curve, easily dropping PO2 quickly if not on 100% FiO2
  43. If we get a drop in oxygen with one lung ventilation, what can we do???
    • Add PEEP to the dependent lung: overcoming all of those pressures, opening the alveoli, and that may help but you may increase shunt. As you expand the dependent alveoli, you compress that capillary, and that will cause blood to go to the non-ventilated lung.
    • Add CPAP to the non-dependent lung:you’re opening up the alveoli and have better gas exchange but pressure is still constricting the capillary but moving bloods towards dependent lung which is ventilated. This would seem better physiologically.
    • Do BOTH:This is thought to be best, restore oxygenation by doing both
  44. When would placing CPAP to the non-dependent lung be contraindicated?
    it worsens operating conditions for the surgeon. Apply pressure to operating area. So if the surgeon is working through a thoracoscope, then this would be contraindicated. Scope already creates a narrow vision and CPAP would make it worse so it’s contraindicated.
  45. After a discussion with the surgeon, there will come a time in which the non-dependent (deflated) lung will need to be re-inflated. Why is it important to do this slowly???
    Neg pressure pulmonary edema (disrupt interstitial pressures) by rapid expansion of a lung so if you do reinflate the non-dependent lung, do it slowly!!!!
  46. Vasodilators and vasoconstriction, will decrease HPV. HPV is very beneficial. Blood is redirected away from the closed alveoli. But in order for that to happen the vessels need a normal tone.  How do we avoid a decrease HPV????
    • Avoid big huge dose of volatiles agents, given 100% oxygen.
    • Volatiles do inhibit HPV but propofol does not vasodilate and inhibit HPV.
  47. In regards to bronchospasm, what should we avoid?
    • Avoid histamine releasing drugs---patient is prone to bronchospasm (because of underlying lung disease) and then there is surgical manipulation of the airway
    • Avoid bronchospasm on DL (lidocaine, fentanyl, deep intubation).
  48. As far as IVF replacement, what should we do???
    • Use caution!!!
    • Limit to basic maintenance requirements.
    • You have dependent edema.
    • If there is blood loss, consider using blood or colloids.
  49. How do you want to extubate a patient after thoracic surgery?
    So you want a patient that’s strong w/extubation, want them awake.
  50. In thoracic surgery, we should maintain two lung ventilation until....
    the pleura is opened
  51. What is the most common cause of pulmonary edema?
    High pulmonary capillary pressures is the most common cause of pulmonary edema. Which is why you should limit IVF.
  52. 1MAC of the agent, increased the shunt by ___%
    4%
  53. Mediastinoscopy
    • Usually done for nodal biopsy.
    • If it’s a big mass (at confluence of superior, anterior and middle mediastinum), it may compress major vascular or airway structures.
    • Impt to know why they're doing a mediastinoscopy.
    • Very dangerous because the great vessels can be obstructed, decreased preload. Or bronchial tree may become obstructed. These changes may become apparent on induction of anesthesia so it’s important to know why they’re having it done.
  54. What can be compressed in a mediastinoscopy??
    Thoracic aorta, innominate artery on right side can be compressed. Trachea can be compressed
  55. What is important for us to know regarding likely compression during the mediastinoscopy??
    • Main thing for us to know if the right innominate is compressed. There would not be pulses in the right extremity.
    • So usually put an art line on the left and BP cuff on left and put the pulse ox on the right. So if you loose the pulse on the right you can still check the BP.
  56. When should you deflate the lung during a scope
    • When the surgeon is doing a scope, because there is no incision, you need to deflate the lung early, often before even turning the patient.
    • Discuss w/the surgeon when they want the lung deflated. Incision and scope in quickly!
  57. If the patient is having open surgery, pain level is 10/10, incision is right over the diaphragm and need to plan for pain control. What kind of pain control is the best?
    Thoracic epidural!!! The only way to interrupt the diaphragm inhibition. It’s a reflex, reflex inhibition of the diaphragm when the incision is over the diaphragm.
  58. The PA catheter generally floats to the right pulmonary artery, why is this??
    the right lung is bigger and there is more flow. Generally they’ll float to the right PA because there is more flow.
  59. If you’re doing a right thoractomy and the PA is in the right side, the PA would be probably inaccurate, why???
    • Right lung deflated and the PA catheter is in the right side (because it usually goes there) to the right PA
    • There would be all this turbulence here because when you deflate that lung, blood will go away from this lung (d/t HPV) so it would be off.
    • Low Pap because not a lot of blood there, but those numbers would be inaccurate
  60. What if you had PA catheter here in right lung, but the non-dependent lung had CPAP on it, would the PAp be accurate?
    It would squash the pulmonary vessels making the reading inaccurate
  61. When would a PAp measurement be accurate in thoracic surgery in the lateral position???
    • If the PA catheter is in dependent lung it would be more likely to be accurate.
    • Not interference in the pressure sensing here in the dependent lung.
    • So in a Left thoracotomy the PA would be much more likely to be accurate.
    • The right lung is dependent and the PA is likely in the right lung and is more likely to be accurate.
  62. What are the sizes of DL tube. What size is most common for women and men?
    • Generally 35, 37, 39 and 41fr are the sizes.
    • 37 women and 39 men.
  63. Why can patients have have airway swelling and worsened obstruction for up to 24hrs post-op from a bronchoscopy?
    • Because you’re restricting their airways. Increase FRC, decrease FEV1 and VC and PO2. So they gas trap.
    • These changes don’t return to normal for 24hrs.
    • And these changes are happening because not only is the fiber optic scope is occluding the airway but there is direct activation of irritant receptors.
  64. What is a rigid bronchoscope, what are the considerations/risks??
    • Big steel bronchoscope and anesthesia is hooked to the side of it.
    • ENT surgeons use it and removal of foreign bodies.
    • The patient must be paralyzed. More likely to have damage to teeth, mouth, trachea, because it’s a rigid bronchoscope.
  65. Why is it important to know WHY the surgeon is doing the mediastinoscopy?
    • If it’s a big mass (at confluence of superior, anterior and middle mediastinum), it may compress major vascular or airway structures.
    • Very dangerous because the great vessels can be obstructed, decreased preload. Or brachial tree may become obstructed.
    • These changes may become apparent on induction of anesthesia so it’s important to know why they’re having it done.
  66. What areas can be compressed by a mediastinal mass???
    Thoracic aorta, innominate artery on right side can be compressed. Trachea can be compressed. Main thing for us to know if the right innominate is compressed
  67. If the RIGHT innominate was compressed, how would we know?
    • There would not be pulses in the right extremity.
    • So usually put an art line on the left and BP cuff on left and put the pulse ox on the right. So if you loose the pulse on the right you can still check the BP.
  68. During a thoroscopy, can you put CPAP on the non-dependent lung?
    No, can't put pressure on the non-dependent lung because it will obstruct the surgeons view

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