Thoracic Anesthesia

Question 1

What does V/Q mismatching lead to?

Answer 1

HYPOXIA

Question 2

Awake Patient

Answer 2

Spontaneous respirations, upright position, & closed chest
Lungs apex maximally dilated
1° ventilation occurs at base
Perfusion also prefers the base
V/Q match preserved

Question 3

Awake Patient in the Lateral Decubitus Position

Answer 3

Spontaneous respirations, lateral decubitus position, & closed chest
V/Q matching preserved
Dependent lung receives > ventilation & perfusion than the upper (non-dependent) lung
Diaphragm displacement cephalad

Question 4

Anesthetized Paralyzed Patient in the Lateral Decubitus Position

Answer 4

Positive-pressure ventilation, lateral decubitus position, & closed chest
Paralysis = PPV
Non-dependent lung ↓resistance
↓FRC
V/Q mismatch
Dependent lung ↑perfusion
Non-dependent lung ↑ventilation

Question 5

Anesthetized Patient Spontaneous Respirations in the Lateral Decubitus Position w/ Open Chest

Answer 5

Spontaneous breathing, lateral decubitus position, & open chest (ex: trauma)
V/Q mismatch ↑shunt
Dependent lung ↑perfusion
Upper long collapse → progressive hypoxemia
- Mediastinal shift
- Paradoxical respirations

Question 6

Anesthetized Paralyzed Patient in the Lateral Decubitus Position w/ Open Chest

Answer 6

Positive pressure ventilation, lateral decubitus position, & open chest (2 lung ventilation)
PPV worsens V/Q mismatch
Non-dependent lung ↑ventilation > perfusion
Dependent lung ↑perfusion > ventilation

Question 7

HPV

Answer 7

Hypoxic pulmonary vasoconstriction
Diverts blood AWAY from hypoxic lung regions
↓blood flow to the non-ventilated lung
Improves arterial oxygen content → improves hypoxemia
↓shunt

Question 8

Normal Pulmonary Blood Flow

Answer 8

Average BOTH lungs being non-dependent (upper)
40%
60%

Question 9

What factors inhibit HPV?

Answer 9

↑pulmonary vascular resistance (↑PAP, volume overload, mitral stenosis)
Hypocapnia (alkalosis or ↓CO2)
↑↓mixed venous PO2
Vasodilators - Nitroglycerin, sodium nitroprusside, β agonists (Dobutamine), Ca2+ channel blockers
Pulmonary infection
Inhalational anesthetics 1 MAC = 4-6% ↑intrapulmonary shunt
Hypothermia

Question 10

One-Lung Ventilation

Advantages

Answer 10

Improved operating conditions & visibility
Facilitates access to the aorta & esophagus
Prevents cross-contamination w/ abscess, secretions, & blood
Press anesthesia gases loss w/ bronchopleural fistula

Question 11

One-Lung Ventilation

Relative Contraindications

Answer 11

Difficult airway w/ poor larynx visualization
Lesion in the bronchial airway precluding bronchial intubation
Thoracic aortic aneurysm
Pneumonectomy
Lobectomy
Thoracotomy or thoracoscopy
Sub-segmental resections
Esophageal surgery

Question 12

One-Lung Ventilation

ABSOLUTE Contraindications

Answer 12

Pulmonary infection
Copious bleeding on one side
Bronchopulmonary fistula
Bronchial rupture
Large lung cyst
Bronchopleural lavage

Question 13

Adult Trachea

Answer 13

11-12cm
Begins at cricoid cartilage (C6)
Bifurcates at the sternomanubrial joint (T5)

Question 14

R Bronchus

Answer 14

Wider (more common to R mainstem)
Diverges away from trachea at 20-25° angle (less acute as compared to L)
RUL orifice sits only 1-2cm to carina
R double-lumen ETT has Murphy eye to ventilate RUL

Question 15

L Bronchus

Answer 15

Narrower
Diverges away from trachea at 40-45° angle
LUL orifice sits about 5cm distal to the carina

Question 16

Double-Lumen Tube Sizing

Answer 16

Short 4’6”-5’3” → 35-37Fr
Medium 5’3”-5’7” → 37-39Fr (most commonly used size 39Fr)
Tall >5’7” → 41Fr

Question 17

DLT Insertion Technique

Answer 17

Curved bladed provides optimal space
Insert w/ blue bronchial tube upward
Rotate 90° towards side to be intubated after tip enters the larynx
Insertion depth 28-29cm at the teeth

Question 18

Tracheal Cuff

Answer 18

5-10mL air

Question 19

Bronchial Cuff

Answer 19

1-2mL air

Question 20

When to check DLT placement w/ fiberoptic scope?

Answer 20

After initial placement

Re-check after positioning patient for surgery in the lateral decubitus position

Question 21

Where to clamp the DLT?

Answer 21

Clamp on the double-lumen connector piece closer to the circuit
Allows lung deflation via port

Question 22

DLT Complications

Answer 22

Advanced too deep (L DLT → excludes R lung from ventilation)
Not inserted far enough
Bronchial tube advances on wrong side
R DLT Murphy eye does not properly align w/ RUL
Bronchial cuff herniation across carina

Question 23

R DLT Indications

Answer 23

Thoracic aortic aneurysm resection
Tumor in the L mainstem bronchus
L lung transplantation or L pneumonectomy (not absolute indication)
L-sided tracheobronchial disruption

Question 24

R DLT Placement Confirmation

Answer 24

Fiberoptic scope
View down both L tracheal lumen & R bronchial lumen
Ensure the Murphy eye aligns w/ RUL to provide adequate ventilation & prevent atelectasis
Retroflex the fiberoptic scope to visualize the RUL via the Murphy eye

Question 25

Bronchial Blocker | Advantages

Answer 25

Patients who require intubation postop do not have to exchange ETT to single lumen

Question 26

Bronchial Blocker | Disadvantages

Answer 26

Blocked lung collapses slowly & sometimes incompletely d/t small channel size w/in the blocker Apply suction or syringe to pull back air & help deflate the lung

Question 27

Univent Bronchial Blocker

Answer 27

ETT placed w/ blocker fully retracted Rotate ETT 90° towards the operative side Push the bronchial blocker into the mainstem bronchus under direct visualization High-pressure low-volume cuff → use minimum volume to prevent leak

Question 28

Lung Resection Indications

Answer 28

Diagnose & treat pulmonary tumors Necrotizing pulmonary infections Bronchiectasis

Question 29

Preop Testing

Answer 29

- CXR - Chest CT - EKG/cardiac clearance - ABG - PFTs - Ventilation-perfusion tests

Question 30

FEV1

Answer 30

Forced expiratory volume in 1 second > 2L or 80% predicted = low risk < 2L or 40% predicted = high risk

Question 31

FEV1/FVC

Answer 31

Normal = 75-80% | High risk patients < 50% predicted

Question 32

High Risk Pneumonectomy Patients

Answer 32

``` ABG PaCO2 > 45mmHg on RA & PaO2 < 50mmHg FEV1 < 2L or < 50% predicted FEV1/FVC < 50% predicted Maximum O2 uptake (VO2) < 10mL/kg/min Maximum voluntary ventilation < 50% predicted ```

Question 33

Split-Lung Function Tests

Answer 33

Uses radio-labeled albumin to calculate predicted pulmonary function, postop outcome, & survival after pneumonectomy Predicts isolated lung FEV1 after the other lung removed Postop FEV1 = preop total FEV1 x % blood flow to the remaining lung Minimal predicted postop FEV1 necessary for long-term survival = 800-1,000mL

Question 34

Small Cell Lung Carcinoma

Answer 34

Lambert-Eaton myasthenic syndrome (LEMS) ↑muscle weakness d/t ↓Ca2+ levels at the NMJ Carcinoid syndrome

Question 35

Lung Oat Cell Carcinoma

Answer 35

Small cell lung carcinoma SIADH ↓UOP, hypervolemia, hyponatremia CHF Pulmonary edema

Question 36

Non-Small Cell Lung Carcinoma

Answer 36

Ectopic parathyroid hormone → Ca2+ problems

Question 37

Patients w/ Lung Cancer | ASSESSMENT

Answer 37

Mass effects - obstructive pneumonia, SVC syndrome, tracheo-bronchial distortion, RLN or phrenic nerve paralysis Metabolic effects - LEMS, hypercalcemia, hyponatremia, Cushing syndrome Metastases → brain, liver, bone, & adrenals Medications - chemotherapy-induced lung/cardiac changes

Question 38

Thoracotomy | Preop Medications

Answer 38

Bronchodilators | Anticholinergics ↓secretions ↑HR to counteract Vagus nerve stimulation when pleura opened

Question 39

Thoracotomy | Monitoring & Equipment

Answer 39

Multiple size ETTs Difficult airway cart w/ pediatric fiberoptic ``` A-line (place on dependent limb to monitor extremity perfusion) CVP or PA catheter less common PIV x2 Blood warmer & rapid infuser available Type & cross PRBCs ```

Question 40

Lateral Decubitus Positioning

Answer 40

Axillary roll to protect brachial plexus | Ensure proper placement

Question 41

Thoracotomy | Postop Pain Management

Answer 41

Thoracic epidural

Question 42

One-Lung Ventilation | Anesthesia Management

Answer 42

Baseline ABG prior to one-lung ventilation Maintain two-lung ventilation until pleura opened Maximum anesthesia depth w/ chest opening & rib splitting Operative lung deflated (clamp & open port; apply suction to help deflate as needed) - 100% FiO2 to dependent lung - Obtain ABG 15min after one-lung ventilation initiated - Continue ABG Q30min-1hr - Volume or pressure controlled - Vt 5-6mL/kg - RR 12-15bpm to maintain PaCO2 35-45mmHg - PEEP 0-5mmHg

Question 43

What is the greatest risk associated w/ one-lung ventilation?

Answer 43

Hypoxemia

Question 44

One-Lung Ventilation | ↑PIP

Answer 44

Check ETT position Reduce Vt & ↑RR to maintain minute ventilation Maintain peak airway pressures < 35cmH2O Plateau airway pressures < 25cmH2O

Question 45

What patients should not receive PEEP?

Answer 45

COPD

Question 46

After deflating the lung, expect to see what vital sign change?

Answer 46

ETCO2 ↑1-3mmHg during one-lung ventilation

Question 47

Response to hypoxemia during one-lung ventilation: | ASSESSMENT & INTERVENTIONS

Answer 47

Confirm ETT placement ↑FiO2 100% Check hemodynamic status → HoTN ↓SpO2 ↓ETCO2 + 2-10cmH2O CPAP to the collapsed lung Periodically inflate the collapsed lung w/ 100% oxygen (inform the surgeon) + 5-10cmgH2O PEEP to the dependent lung Continuous insufflation to the collapse lung w/ 100% FiO2 Early ligation/clamping to the ipsilateral pulmonary artery (when performing pneumonectomy) ↑blood flow to one-lung & improves V/Q match

Question 48

One-Lung Ventilation Alternatives

Answer 48

Stop ventilation for short period & used 100% FiO2 insufflated at rate > O2 consumption Apneic oxygenation 10-20min → progressive respiratory acidosis ↑PaCO2 6mmHg 1st min & 3-4mmHg each additional min High frequency jet ventilation - low volumes w/ high pressure

Question 49

Emergence

Answer 49

Inflate lung to 30cmH2O Valsalva requested per surgeon to check for leaks or microbleeding (watch monitor *bradycardia*) Thoracostomy tubes places Exchange DLT to single lumen prior to transporting to ICU when patient remains intubated after surgery (consider tube exchanger w/ DVL)

Question 50

Thoracic Anesthesia Complications

Answer 50

``` Hypoxemia or respiratory acidosis Postop hemorrhage Arrhythmias (Afib most common) Bronchial rupture Acute R ventricle failure Positioning injuries ```

Question 51

What contributes to the 1° complication postop thoracic surgery developing?

Answer 51

Hypoxemia & respiratory acidosis Atelectasis & shallow breathing d/t incisional pain Gravity dependent fluid transudation into the dependent lung

Question 52

Postop Hemorrhage S/S

Answer 52

Occurs in 3% thoracic surgery Associated w/ 20% mortality CT drainage > 200mL/min Hypotension Tachycardia ↓Hct

Question 53

What causes bronchial rupture?

Answer 53

Excessive bronchial tube cuff inflation

Question 54

Acute RV Failure S/S

Answer 54

Low CO ↑CVP Oliguria

Question 55

VATS

Answer 55

Video-assisted thoracoscopic surgery Uses video camera & surgical instruments inserted via port in the thoracic wall Typically 3-5 ports Staplers used to resect lung tissue & divide large blood vessels

Question 56

VATS | Indications

Answer 56

``` Lung biopsy Wedge resection Hilar & mediastinal mass biopsy Esophageal & pleural biopsy Pericardiectomy Pneumonectomy ```

Question 57

VATS | Advantages

Answer 57

``` Smaller incision No intraop rib spreading Less postop pain ↓risk postop hypoxemia Faster recovery & discharge from hospital ```

Question 58

VATS | Anesthetic Approaches

Answer 58

Local, regional (epidural), or general anesthesia Two or one-lung ventilation *General anesthesia most common approach

Question 59

VATS | Preop Evaluation & Planning

Answer 59

Discuss pain management options w/ patient | Consider conversion to open thoracotomy & consult surgeon Same preop evaluation as thoracotomy

Question 60

VATS | Intraop Anesthetic Management

Answer 60

``` GA one-lung ventilation w/ DLT or bronchial blocker Surgeon injects LA prior to placing ports Lateral decubitus position PIV x2 A-line ABG Q30min-1hr Suction lung & gently re-inflate Exchange DLT → single lumen CT placed prior to closing ```

Question 61

VATS | Intraop Complications

Answer 61

``` CO2 insufflation to improve surgical visualization → hemodynamic compromise or gas embolism enters venous circulation (VAE) Tension pneumothorax Hemorrhage Diaphragm or other organ perforation Positioning & DLT complications ```

Question 62

Mediastinoscopy

Answer 62

Lymph node or tissue biopsy to diagnose lung carcinoma, thymoma, or lymphoma or to determine intrathoracic tumor resectability Performed via small transverse incision above the suprasternal notch Scope similar appearance to laryngoscope inserted anterior to the trachea to biopsy lymph nodes

Question 63

Mediastinoscopy | Anesthetic Considerations

Answer 63

Chest roll behind back to help facilitate head/neck extension GETA Innominate artery supplies R arm & R common carotid Place A-line and/or Pox on R arm Absent waveform indicates innominate artery compression → ask surgeon to reposition the scope BP cuff on L arm Central airway obstruction d/t trachea compression during induction or mediastinoscope manipulation near the trachea

Question 64

Mediastinal Tumors S/S

Answer 64

Often asymptomatic & discovered incidentally on CXR Symptomatic masses are usually malignant w/ extensive involvement → airway obstruction, impaired cerebral circulation, anatomy distortion Frequently associated w/ systemic syndromes Cough, dyspnea, stridor, jugular distention, exaggerated BP changes associated w/ positioning SVC syndrome

Question 65

SVC Syndrome

Answer 65

Progressive mediastinal tumor growth results in SVC compression → obstructs venous drainage into the upper thorax

Question 66

SVC Syndrome S/S

Answer 66

Venous distension in the neck, thorax, & upper extremities Facial, conjunctiva, neck & upper chest edema Mouth & larynx edema associated w/ severe airway obstruction Mucosal edema & direct compression → cyanosis d/t compromise trachea airflow Depressed CO d/t impeded upper body VR or direct mechanical heart compression from the tumor Venous backflow into the upper extremity IV lines ↑ICP

Question 67

Mediastinoscopy | Relative Contraindications

Answer 67

``` SVC syndrome Previous medistinoscopy (scar tissue) Airway obstruction & distortion Impaired cerebral circulation Myasthenic syndrome ```

Question 68

Mediastinoscopy | ABSOLUTE Contraindications

Answer 68

Inoperable Coagulopathy (hemorrhage risk) Thoracic aortic aneurysm

Question 69

Mediastinoscopy | Preop Considerations

Answer 69

Assess airway compromise S/S including dyspnea, tachypnea, tracheal deviation CXR & CT scan Assess tumor size & location Evaluate tracheal distortion or compression PFTs obtained in upright & supine position Flow-volume loops detect airway obstruction Patient able to lay flat? SVC obstruction or impaired cerebral circulation Muscle relaxants, coughing & breath holding, and/or position changes potential to worsen symptoms

Question 70

Mediastinoscopy | Monitoring & Equipment

Answer 70

PIV x2 Consider placing in lower extremities d/t SVC syndrome Monitor R radial pulse (doppler, A-line, Pox) BP cuff on L arm PNS

Question 71

Mediastinoscopy | Anesthetic Management

Answer 71

Deep anesthesia to blunt autonomic reflexes Avoid N2O & monitor for pneumothorax Innominate, R subclavian, or R carotid artery compression → distal pulse loss & postop neuro deficits RLN or phrenic nerve injury Vagal-mediated reflex bradycardia d/t trachea or vessels compression

Question 72

Mediastinoscopy | Emergence

Answer 72

4/4 twitches Airway reflexes present SVC syndrome patients awake to prevent obstruction Postop CXR on ALL patients to r/o pneumothorax

Question 73

Mediastinoscopy | COMPLICATIONS

Answer 73

``` Mediastinal hemorrhage Pneumothorax RLN injury Phrenic nerve injury or L hemiparesis Esophageal injury Air embolism → HOB elevated 30° Dysrhythmias Acute airway obstruction ```

Question 74

Mediastinal Hemorrhage

Answer 74

Most common complication Prevention → limit IVF especially in SVC syndrome patients ↑CVP ↑risk

Question 75

Pneumothorax

Answer 75

2nd most common mediastinoscopy complication

Question 76

RLN Injury

Answer 76

``` 3rd most common mediastinoscopy complication NIMS tube provides nerve monitoring - Place w/ video laryngoscope Monitor postop respiratory status Hoarseness or vocal cord paralysis ```

Question 77

Acute Airway Obstruction

Answer 77

Prolonged tumor cause tracheal malasia leading to tracheal collapse → GA w/ reinforced ETT Place patient in lateral, reverse Trendelenburg, prone, or high Fowlers position to help shift mass away from the trachea or SVC & relieve the obstruction

Question 78

Difficult Intubation and/or Ventilation

Answer 78

Various ETT sizes, establish ability to ventilate BEFORE muscle relaxation, & provide intraop muscle relaxation to prevent coughing/straining

Question 79

Interventions to implement that ↓respiratory complications incidence in high risk patients undergoing thoracic surgery:

Answer 79

Smoking cessation Physiotherapy Thoracic epidural analgesia

Question 80

Patients undergoing pulmonary resection preop evaluation:

Answer 80

3 parts - Lung mechanical function - Pulmonary parenchymal function - Cardiopulmonary reserve

Question 81

What patient population is at an increased risk for cardiac complications, particularly arrhythmias, after pulmonary resections?

Answer 81

Geriatric patients | Best predictor post-thoracotomy outcome in the elderly = preop exercise capacity