Thoracic Anesthesia

Front 1

Where is the primary respiratory center?

Back 1

Primary respiratory centers (dorsal & ventral respiratory groups) located in medulla

Front 2

Where is the secondary respiratory center?

Back 2

Secondary respiratory centers (apneustic & pneumotaxic centers) located in pons

Front 3

Where do opioids work?

Back 3

All opioids cause dose-dependent respiratory depression through direct μ2 receptor stimulation at brainstem respiratory centers located superficially in the floor of the 4th ventricle (medulla & pons)

Front 4

Three exogenous substances that stimulate peripheral chemoreceptors:

Back 4

Cyanide, doxapram, nicotine

Front 5

What is doxapram?

Back 5

It also stimulates chemoreceptors in the carotid arteries, which in turn, stimulates the respiratory centre in the brain stem.

Front 6

Hering-Breuer reflex

Back 6

Pulmonary stretch receptors with in smooth muscles of small airways triggered by lung inflation ( through the SR)
Vagus nerve carries sensory (afferent) impulses of Hering-Breuer reflex. Protective mechanism not activated until tidal volume > 1.5L
Strong & physiologically significant in neonates

Front 7

Percent of tidal volume in spontaneously breathing adult that is dead space:

Back 7

average is 33%

Front 8

Percent of tidal volume in a paralyzed, mechanically ventilated patient that is dead space:

Back 8

40-60%

Front 9

Normal dead space to tidal volume (VD/VT) ratio?

Back 9

Normally, anatomic dead space is almost = physiologic dead space
Alveolar dead space is small
VD/VT is ~ 0.33 (33%)

Front 10

With lung disease, physiologic dead space

Back 10

↑ & VD/VT ↑
In pt with COPD, VD/VT ↑ to 60-70%

Front 11

What do changes in dead space cause?

Back 11

Mild dead space ventilation
PaCO2 increases
Severe dead space ventilation
PaO2 decreases

Front 12

Factors associated with increased dead space

Back 12

Increased age
Positive pressure ventilation
Pulmonary embolism
Patient with lung disease

Front 13

IRV

Back 13

volume which can be inhaled additionally after normal inspiration ( 3.6 L)

Front 14

ERV

Back 14

volume which can be exhaled additionally after normal expiration ( 1.2 L)

Front 15

RV

Back 15

volume remaining in the lungs after maximal expiration ( 1.2 L)

Front 16

VC

Back 16

volume which can be exhaled after maximal inspiration (sum of TV, IRV, ERV) (4.8 L)

Front 17

IC

Back 17

volume that can be inhaled additionally after normal expiration (sum of TV and IRV) (4.1 L)

Front 18

FRC

Back 18

volume remaining in the lung after the end of a normal expiration (sum of ERV and RV) (2.4 L)

Front 19

TC

Back 19

volume filling the lung after maximal inspiration (sum of TV, IRV, ERV, & RV) ( ~ 6 L)

Front 20

Risk assessment for postop pulmonary complication- spirometry values

Back 20

Expiratory Spirogram
a. Normal ( % FVC + % FEV1/FVC>150 )= 0
b. % FVC + % FEV1/FVC = 100-150=1
% FVC + % FEV1/FVC < 100 2
Preop FVC < 20 ml/kg=3
Post op bronchodilator FEV1/FVC < 50%= 3

Front 21

Risk assessment for postop pulmonary complication- cardiac

Back 21

Controlled HTN or post MI >2 yrs= 1
DOE, orthopnea, PND, dependent edema, CHF, angina=1

Front 22

Risk assessment for postop pulmonary complication- ABG

Back 22

PaCO2 > 50 mmHg or PaCO2 < 60 mmHg on RA
Metabolic pH abnormality > 7.50 or < 7.30
Both are 1 pt

Front 23

Risk for postop pulmonary complications- neuro

Back 23

1 pt for any irregularities

Front 24

Risk for postop pulmonary complications- postop ambulation

Back 24

In bed >36 hrs= 1pt

Front 25

Risk for postop pulmonary complications score stratification

Back 25

0 Points= Low Risk; 1-2 Points = Moderate Risk; 3 Points = High Risk

Front 26

Normal values measured with dynamic spirometry in healthy 70 kg ♂:

Back 26

FVC = 5L
FEV1 = 4 L
FEV1/FVC = 0.75-0.85

Front 27

Spriometry criteria for lung resection

Back 27

FVC > 50% (2L), FEV1>60% predicted, FEV1:FVC > 50%, Diffusing capacity for CO >60% predicted, Arterial C02 <45mm HG

Front 28

The best and most current method of estimating split lung function is to perform....

Back 28

Quantitative VQ scan: calculate the FEV1 volume of left over lung by knowing percentage of perfusion to left and right lung

Front 29

What is the minimum required value on quantitative VQ in order to proceed with pneumonectomy?

Back 29

The minimum acceptable predicted postoperative FEV1 is 800 ml. If the predicted postoperative FEV1 volume is less than 800 milliliters the patient is not a candidate for pneumonectomy.

Front 30

What can be done if split function test is <800cc?

Back 30

Occlude PA. If the pulmonary artery pressure is elevated at rest or with exercise, the patient is not a candidate for pneumonectomy. The patient obviously has no capillary bed reserve and is not able to tolerate the loss of vascular bed. He will develop cor pulmonale and the expected 5 year survival will be less than 50%.

Front 31

Name absolute indications for one lung ventilation

Back 31

Prevent spillage and contamination of the healthy lung with purulent material or blood ( lung abscess or massive hemoptysis)
Unidirectional ventilation and maximizing oxygenation to the healthy lung ( bronchopleural fistula)
Unilateral bronchopulmonary lavage

Front 32

Name relative indications for one lung ventilation

Back 32

Facilitate surgical exposure ( collapsing the non-dependent lung during aortic aneurysm and esophageal surgeries

Front 33

Name patient related indications for OLV

Back 33

Confine infection/ bleeding to one lung
Lung separation due to :
tracheobronchial disruption
bronchopleural fistula
lung cyst/bulla
severe hypoxemia due to unilateral lung disease

Front 34

Vent goals during OLV

Back 34

Reduce TV to maintain PAP < 30 cmH20; increase RR to maintain MV
VT for dependent lung 10-12 ml/kg
Rate adjusted for PaCO2 ~ 35 ( CO2 elimination is usually not affected by OLV)

Front 35

Management of hypoxemia during OLV

Back 35

a. periodic inflation of collapsed lung with O2
b. ligation of ipsilateral pulmonary artery
c. 5-10 cm H20 CPAP to collapsed lung ( most profound maneuver to manage hypoxemia but can also interfere with surgery) (5-10 cmH2O RELIABLY improves PaCO2

Front 36

Name complications of bronchoscopy

Back 36

Bronchospasm/laryngospasm ( light anesthesia)
Hypoxemia: large scope or atelectasis ( suctioning while scope is in a wedged position)

Increased airway obstruction after bronchoscopy secondary to mechanical activation of cough and irritative reflexes and by direct trauma-induced mucosal edema ( can use helium-oxygen mixture to decrease airflow resistance)

Front 37

Where do you place the arterial line during mediastinoscopy?

Back 37

Arterial line on right side to see if they’re compressing enominate A.

Front 38

Eaton Lambert Syndrome

Back 38

Lambert–Eaton Myasthenic Syndrome (LEMS) is a rare autoimmune disorder that affects voltage-gated calcium channels on the pre-synaptic membrane of the NMJ.
Inhibition of these calcium channels prevents acetylcholine from being released from the presynaptic terminal and the subsequent stimulation of the post-synaptic terminal which would lead to muscle contraction.

Front 39

Reasons for mediastinoscopy

Back 39

Performed before thoracotomy to establish diagnosis and/or determine resectability of lung carcinoma and establish correct diagnosis in patients suspected of lymphoma and those with mediastinal mass.

Front 40

Contraindications to mediastinoscopy

Back 40

Contraindicated in upper airway or SVC obstruction ; impaired cerebral perfusion or evidence of myasthenic syndrome due to lung CA
Can pt be supine without dyspnea?

Front 41

Complications of mediastinoscopy

Back 41

Hemorrhage
Pneumothorax
Tension pneumothorax
RLN injury: permanent in 50% of cases
VAE ( risk if spontaneously breathing)
Compression of the innominate artery ( A line and oximeter on R arm)
Autonomic reflexes due to stretching of trachea, vagus, or great vessels→ reflex bradycardia
Tracheal tear
Mortality 0.1%

Front 42

Pt positioning during VATS

Back 42

Need operative lung ↓
Can’t easily retract lung
Lateral decub
Deflate lung soon as possible after induction. Takes up to 30 min for complete collapse.

Front 43

Anesthesia concern during VATS

Back 43

CO2 insufflation into pleural cavity to facilitate visualization
Insufflation pressures should be kept low (< 5 mmHg) because high pressures can cause mediastinal shift
CPAP can’t be used
Can add PEEP to dependent lung
Pain following VATS < open thoracotomy
Respiratory function better preserved following VATS

Front 44

What's the signifigance of VC?

Back 44

Significant reductions in vital capacity (less than 20 cc/Kg of ideal body weight) indicates that the patient is at a higher risk for postoperative respiratory complications. This is because vital capacity reflects the patient's ability to take a deep breath, to cough, and to clear the airways of excess secretions.

Front 45

What VC is required for extubation?

Back 45

10 - 15 ml/Kg

Front 46

FEV25-75%

Back 46

This measurement describes the amount of air expelled from the lungs during the middle half of the forced vital capacity test. Many physicians like to look at this value because it is an indicator of obstructive disease.

Front 47

MVV

Back 47

Maximal Voluntary Ventilation- this value is determined by having the patient breathe in and out as rapidly and fully as possible for 12 -15s. Measure of respiratory muscle strength. Effort dependent***

Front 48

FEV1/FVC in obstructive lung disease

Back 48

. If the %predicted for FEV1/FVC is 69% or lower, then the patient has an obstructed lung disease.

Front 49

FEV1/FVC in restrictive lung disease

Back 49

88%-90% or higher, then the patient has a restricted lung disease