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Miller > Ch 66 Thoracic Anesthesia > Flashcards

Ch 66 Thoracic Anesthesia Flashcards

1
Q

What are the major causes of perioperative morbidity and mortality in thoracic Anesthesia patients?

A

Major respiratory complications - atelectasis, pneumonia, respiratory failure (15-20%)
Cardiac 10-15%

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2
Q

What are the 3 areas of respiratory function important for assessment in thoracic surgical patients?
(“3 legged stool”)

A
  1. Respiratory mechanics (FEV1, FVC, RV/TLC)
  2. Gas Exchange (paO2, PaCo2, DLCO)
  3. Cardiorespiratoy interaction (VO2max, 6min walk test)
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3
Q

What is the most valid single test for postthoracotomy respiratory complications? How is it calculated?

A

predictoed postoperative FEV1 (ppoFEV1)
ppoFEV1% = preoperative FEV1(1-%fuctionallungtissueremoved/100)
Estimate % of lung tissue removed by assessing how many segments are being removed (out of a total of 42)
if ppoFEV1% is >40%, there is low risk for post resection respiratory complications

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4
Q

How many segments are in each part of the lungs?

A

RUL: 6, RML: 4, RLL: 12
LUL: 10, LLL: 10

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5
Q

How are the DLCO and FEV1 affected by preoperative chemotherapy?

A

DLCO: decreases
FEV1: no change
A low DLCO in patients treated with chemotherapy may be the most important predictor in this group

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6
Q

What levels of preoperative DLCO and FEV1 is associated with an unacceptably frequent perioperative mortality rate?

A

<20% for both

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7
Q

What is the VO2max where the risk of morbidity and mortality is increased and when is it very high?

A

Increased risk <15mL/kg/min

Very nigh <10mL/kg/min

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8
Q

How do you estimate VO2 max from a 6 min walk test?

A

distance (meters)/30

e.g., 450m/30 estimated VO2max 15Ml/kg/min

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9
Q

What is the only therapy that decreases right-sided heart strain in COPD?

A

Administration of oxygen

-home oxygen for all patients with PaO2 < 55mmgHg at room air or <44 mmHg with exercise

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10
Q

What happens to a bulla in the presence of PPV?

A

The pressure in the bulla becomes positive (is usually slightly negative compared to its surroundings). This increases the risk for rupture, tension PTX, and bronchopleural fistula

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11
Q

For how long before surgery does a patient need to quit smoking for pulmonary complications to be decreased?

A

4 weeks

carboxyhemoglobin decreases with 12 hours without smoking.

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12
Q

What time of lung cancer is most common? What is its 5 year survival?

A

NSCLC (75-80%)

5 year survival 40%

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13
Q

Which type of lung cancer is strongly linked to cigarette smoking?

A

NSCLC - specifically squamous cell carcinoma

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14
Q

Which between SCLC and NSCLC is most likely to be surgically treatable

A

NSCLC may be amenable to surgical resection.

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15
Q

What paraneoplastic syndrome can be seen with SCLC?

A

Lambert-Eaton (impaired release of ACh from nerve terminals

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16
Q

What is the worry with prior bleomycin chemotherapy?

A

Pulmonary toxicity from high FiO2. Use low as possible FiO2. Bleomycin is not used for primary lung cancer but is used for germ cell cancers that may metastasize to the lungs.

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17
Q

What are predictors for hypoxemia with OLV?

A
  • Hypoxemia with 2LV
  • Right Lung Operative lung (larger shunt fraction)
  • Normal FEV1
  • Supine position during OLV
  • High percentage of ventilation or perfusion to operative lung on pre-op VQ scan
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18
Q

What happens to the PaCO2/ETCO2 gradient during OLV

A

Increases

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19
Q

What does a severe (>5mmHg) or prolonged decrease in EtCO2 indicate with initiation of OLV?

A

Maldistribution of perfusion between ventilated and non ventilated lungs and may be an early warning sign of someone who may desaturate during OLV

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20
Q

What is a typical distance from the carina to the RUL bronchus?

A

1.5-2cm

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21
Q

What is an anatomical landmark that helps distinguish the left lower lobe from the left upper lobe?

A

Longitudinal elastic bundles extend down the posterior membranous walls of the bronchi. They extend into the left lower lobe.

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22
Q

What are the three segments of the RUL?

A

Apical, anterior, posterior

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23
Q

What is the smallest size ETT that can typically be used with a standard bronchial blocker and pediatric (3.7mm) scope?

A

7.0

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24
Q

What are options for lung isolation with a tracheostomy?

A
  1. SLT through teach and a bronchial blocker
  2. Use a disposable cuffed tracheostomy cannula with a bronchial blocker
  3. replacement of tracheostomy cannula with a specially designed DLT (e.g., Naruke DLT)
  4. Placement of small DLT through tracheostomy stoma
  5. oral access to airway for standard placement of DLT or bronchial blocker
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25
Q

Which is the anatomical site related to the majority of intrapoerative nerve injuries in the lateral position?

A

Brachial plexus (compression injuries in the dependent arm, stretch injuries in the nondependent arm)

26
Q

What happens to FRC and compliance in the dependent lung in the lateral position once anesthetized?

A

Both decrease.

27
Q

How does perfusion change in the lateral position? How does pulmonary A-V shunt change in the lateral position?

A

Blood flow to dependent lung is thought to be increased by 10% compared to supine.
Shunting will usually increase from 5% in supine position to 10-15% in the lateral position.

28
Q

What are the arbitrary limits for fluid balance and crystalloid administration for the first 24h post-pulmonary resection surgery?

A

Total positive fluid balance should not exceed 20mL/kg

Crystalloid should be less than 3L in 24h

29
Q

How does hypothermia affect HPV?

A

It inhibits it

30
Q

Why do we denitrogenate the operative lung prior to collapse? How is this done?

A

Allows for better collapse

Ventilate with 100% oxygen immediately before isolation

31
Q

What measure of lung volume correlates most with pulmonary vascular resistance?

A

FRC
PVR is lowest at FRC and increases as lung volume rises or falls above or below FRC.
Try to main ventilated lung closest t oFRC while facilitating collapse of non ventilated lung to increase its PVR
PVR gets higher again towards TLC

32
Q

Which position is associated with greater PaO2 with OLV: supine or lateral?

A

Lateral

33
Q

By how much can hypoxic pulmonary vasoconstriction decrease blood flow to non ventilated lung?

A

50%

34
Q

Describe the onset of hypoxic pulmonary vasoconstriction?

A

Biphasic: rapid-onset phase begins immediately and plateaus at 20-30mins. The delayed phase begins after 40 mins and plateaus after 2 hours

35
Q

Describe the offset of HPV?

A

Biphasic - may not return to baseline for several hours after a prolonged period of OLV

36
Q

What can decrease or impair HPV?

A

Vasodilators (nitroglycerin/prusside)
Older volatile agents (halothane>enflurane>isoflurane)
Respiratory alkalosis

37
Q

What is the relationship between cardiac output and PaO2 during OLV?

A

at baseline (patient’s normal/optimized cardiac output) PaO2 is best.
Increasing CO to supranormal levels with inotropes can decrease PaO2 by increasing shunt fraction
Too low of a CO decreases mixed venous significantly, reducing PaO2.

38
Q

Do R or L-sided thoracotomies result in larger shunt and lower PaO2 during OLV?

A

R-sided because the R lung is larger and normally 10% better perfused than the left. Overall mean PaO2 difference between L and R thoracotomies during stable OLV is ~100mmHg

39
Q

Do patients with normal spirometric lung function pre-op more or less likely to desaturate during OLV?

A

More likely than emphysematous lungs.

40
Q

Name therapies for hypoxemia on OLV?

A
  • Resume 2LV
  • Increase FiO2
  • Recruit non-operative lung & add PEEP
  • Add CPAP to operative lung; can use intermittent re-inflation of the operative lung
  • Improve cardiac output
  • Check position of DLT or bronchial blocker
  • Mechanical restriction of blood flow to the operative lung (clamp the PA)
41
Q

List methods of ventilation for rigid bronchoscopy

A
  1. Spontaneous ventilation
  2. Apneic oxygenation (use optiflow) will need to ventilate every 3 mins (interrupt surgery)
  3. PPV via ventilating bronchoscope (significant leak)
  4. Jet ventilation
    - Likely will need some form of TIVA for these techniques
42
Q

Which artery is at risk for compression during mediastinoscopy?

A

Innominate artery (brachiocephalic)- supplies blood to right arm and right common carotid. Therefore, need to monitor the pulse in the right arm during the procedure (pulse oximeter or art line)

43
Q

What are some mainstays of treatment for hemorrhage during mediastinoscopy?

A
  • stop surgery and pack wound
  • resuscitate, call for help
  • large bore venous access in lower limbs
  • art line if not already
  • DLT or bronchial blocker if possible need for thoracotomy
44
Q

What is the ppoFEV1 threshold for increased risk for VATS vs open thoracotomy?

A

ppoFEV1:
30% VATS
40% open thoracotomy

45
Q

What are the advantages to VATS vs open thoracotomy?

A
  • reduced hospital length of stay
  • less blood loss
  • less pain
  • improved pulmonary function
  • early patient mobilization and earlier return to daily activities/work
  • less inflammatory reaction
46
Q

What kind of tumors are usually removed with sleeve resections?

A

Bronchogenic carcinomas, carcinoid tumours, primary airway tumours (essentially the surgeon removes a piece of the bronchus)

47
Q

How much fluid in the first 24h post-thoracic surgery is considered “excessive” and putting patient at higher risk for acute lung injury?

A

3L in 24 hours

48
Q

What is the cure rate of esophageal cancer with esophagectomy?

A

10-50%

49
Q

Which esophagectomy approach does not require OLV?

A

Transhiatal - upper abdominal incision and Left neck incision

50
Q

What is the difference between Type I and II Hiatal hernias?

A

Type I: “sliding hernias” 90% of hernias - EG Junction herniate into thorax, particularly with changes in pressure (coughing, breathing)
Type II: “paraesophageal hiatal hernia” EG junction still in abdomen, but portions of stomach herniate into thorax. Common complications: bleeding, anemia, gastric volvulus

51
Q

What is the typical surgical approach for a perforated esophagus?

A

R or L thoracotomy

52
Q

what is achalasia?

A

lack of peristalsis in esophagus and failure of lower sphincter to relax with swallowing. Leads to esophageal distension, chronic regurgitation and aspiration

53
Q

What is the risk with anesthetizing a patient with Zenker diverticulum? Can anything be done to decrease this risk?

A

Risk of regurgitation of contents of diverticulum (fasting does not ensure that contents will empty). Can ask patient to express/ regurgitate contents before induction (they may be used to doing this)

54
Q

Name different methods for oxygenation and ventilation during a tracheal resection

A
  • standard oraltracheal intubation
  • sterile SLT into opened trachea or bronchus distal to resection
  • Jet ventilation through stenotic area
  • high frequency PPV
  • CPB
55
Q

What is the worry with re-expansion of the lung following decortication for a chronically collapsed lung?

A

Pulmonary edema with reexpansion. Should be done gradually.

56
Q

What are the anesthetic challenges/considerations for intraoperative management of a BPF?

A
  • need for lung isolation to protect healthy lung regions
  • possibility of tension PTX with PPV
  • possibility of inadequate ventilation from air leak through fistula
57
Q

What are your goals with managing a BPF intraoperatively?

A
  • ensure chest tube in place on side of BPF

- avoid PPV on side of BPF (awake DLT insertion, asleep spontaneously breathing DLT insertion, rapid lung isolation)

58
Q

What is the risk of PPV in a patient with a bullae

A

Bullae pressure becomes positive (is normally negative) and may expand, causing rupture, tension PTX. Suggested to do rapid lung isolation or ventilate with small TV

59
Q

What are signs of a BPF following a pneumonectomy?

A
  • dyspnea
  • SubQ emphysema
  • contralateral (to pneumonectomy) deviation of trachea
  • decrease of fluid level on operative side (typically chest nearly white out post pneumonectomy)
60
Q

Is there any special management for patients coming for surgery with a previous lung transplant?

A

Generally, no if double lung transplant.
If requiring OLV, be careful of anastomosis when placing DLT/blocker (use scope)
-If single lung transplant, particularly with native lung emphysema, there will be an imbalance in pulmonary compliance (may require DLT and isolation)

61
Q

Pulmonary Hemorrhage

A

…

Miller (5 decks)

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