Thoracic Pre-op and Positioning

Question 1

What are indications for non-cardiac thoracic surgery?

Answer 1

-Bronchogenic carcinoma
-Thoracic tumors
-Infections – Chronic abscess
-COPD
-Trauma
-Vascular Disease – SVC syndrome
-Congenital anomalies

Question 2

How can other cancer treatments affect thoracic surgery?

Answer 2

-Radiation: Adhesions (friable tissue- be gentle with intubation. If in chest, can tear great vessels and be at inc risk for bleeding). Be prepared - order blood products, check labs, can preemptively transfuse.

-Chemotherapy agents: Bleomycin causes pulmonary toxicity. Need to reduce FiO2 due to oxygen toxicity.

Question 3

What is the survival rate with bronchogenic carcinoma without surgery?

Answer 3

There is only a 12–18-month survival on bronchogenic carcinoma with medical and no surgical treatment.
-Have to rush to surgery even if not optimized due to short life expectations without surgery.

Question 4

What are things you should ensure to assess pre-operatively for the patient having thoracic surgery?

Answer 4

-General: weakness, weight loss, anorexia, exertional dyspnea, productive cough, chest pain, hemoptysis.
-Labs: CBC, cultures, BMP
-X-Ray
-Operability (how much tissue is being removed)
-PFTs

Question 5

Why is it important to assess the x-ray preop?

Answer 5

-Location of tumor
-Tracheal shifts
-Pulmonary edema
-Compression of mediastinal structures

Nagelhout:
-This information is important to predict whether intubation will be difficult, whether induction of anesthesia could cause collapse of the airway, or whether surgical dissection may be difficult and potentially involve excessive bleeding.

Question 6

Why do you assess PFTs pre-op?

Answer 6

Barash:
1) Identify patients at inc risk of postop M&M. How much lung tissue is being removed matters
2) Identify patients who may need short or long-term ventilation post op
3) Identify benefits and reversible airway obstruction with the use of bronchodilators.

Question 7

What is FEV1?

Answer 7

Forced Expiratory Volume in one second.

Barash:
-A more direct indication of airway obstruction.

Question 8

What is FVC?

Answer 8

Forced Vital Capacity
-The total volume of air a patient is able to exhale for the total duration of the test during maximal effort.
-The deepest breath they can take and how much they can get out.

Question 9

What does the FEV1/FVC ratio mean?

Answer 9

The percentage of the FVC expired in one second.
-Ratio that distinguishes between restrictive and obstructive lung disease.
-Normal = 4/5 or 80% (0.8)

Question 10

What is the FEV1/FVC ratio in Obstructive diseases? (Asthma, bronchitis, emphysema)

Answer 10

-FVC is normal, but the FEV1 is abnormal.
-Can get air in, but can’t get air out quickly.
-FEV1/FVC = < 80% (Ex: 2.5/5)

Question 11

What is the FEV1/FVC ratio in Restrictive diseases? (Pulmonary fibrosis, scoliosis, contractures/burn patients)

Answer 11

-Ratio is the same, but both values are reduced. Overall drop in FVC.
-FEV1/FVC >/= 80% (ex: 3.2/4)

Question 12

How do you calculate a predicted postop FEV1?

Answer 12

Barash:
-By multiplying the preoperative FEV1 by the percentage of lung tissue expected to remain following resection, a predicted postoperative FEV1 can be calculated.
-Patients with a predicted postoperative FEV 1 value above 40% are at reduced risk and those with predicted postoperative FEV below 30% are at increased risk.
-Those patients who fall into the latter category are more likely to need postoperative ventilation.

Question 13

What does it mean if the PPO FEV1 > 40%?

Answer 13

Low-risk patient.
-Likely to be extubated in the OR, immediately following surgery.

Question 14

What does it mean if the PPO FEV1 is 30-40%?

Answer 14

Intermediate risk patient.
-Consider extubation in OR if METS are ok
-Extubation should be based on exercise tolerance, V/Q scan, and associated comorbidities (renal, age, cardiac, or COPD)
-Care individualized based on assessment parameters.

Question 15

What does it mean if the PPO FEV1 is <30% ?

Answer 15

Patient is high risk for requiring post-op mechanical ventilation.
-Consider weaning the patient in the ICU.

Question 16

How does the pattern and rate of breathing change in Obstructive diseases?

Answer 16

For constant minute ventilation, the work done against airflow resistance (obstructive) decreases when breathing is slow and deep.
-Slow, deep breaths (!)

Question 17

How does the pattern and rate of breathing change in Restrictive diseases?

Answer 17

For constant minute ventilation, the work done against elastic resistance (restrictive) decreases when breathing is rapid and shallow (e.g., as in pulmonary infarct or pulmonary fibrosis).
-Rapid, shallow breaths (!)

Question 18

Review Flow/Volume loops on slide 10 & 11

Answer 18

Yes

Question 19

Describe the Flow-Volume Loop with Restrictive Disease.

Answer 19

-Same shape as normal, just much smaller. FVC is reduced. Shifted towards lung volume closer to 0.

Barash:
-The flow-volume curves of these patients are normal in shape, but the lung volumes and peak flow rates are decreased.
-FEV1/FVC ratio is normal
-TLC is markedly decreased (small loop)

Question 20

Describe the Flow-Volume Loop with Obstructive Disease.

Answer 20

-Can get lots of air in and may be air trapping. Can’t get air out. Indicated by slow exhalation.

Barash:
-In these patients, the effort-independent portion of the flow-volume curve is markedly depressed inward, with reduction of the flow rate at 25-75% of FVC.
-Grossly decreased FEV1/FVC ratio
-TLC increases secondary to increases in Residual Volume (RV).

Question 21

What part of the flow-volume loop indicates patency of larger airways?

Answer 21

The shape and peak airflow rates during expiration at high lung volumes are effort dependent, but indicate the patency of the larger airways.

Question 22

What part of the flow-volume loop indicates patency of small airways?

Answer 22

Effort-independent expiration occurs at low lung volumes and usually reflects small airways.

Barash:
-This is best measured by forced expiratory flow (FEF) during the middle half of the FVC (FEF 25%–75% ).

Question 23

What factors identify a low-risk patient?

Answer 23

-FEV-1 >2 liters
-Predicted FEV-1 > 40%
-Absence of cardiac disease
-Ability to climb 5 flights of stairs

Question 24

What factors identify a high-risk patient?

Answer 24

-FEV-1 < 0.7 liters
-FEV-1 predicted < 30%
-PCO2 >45
-PO2 < 50
-Age > 70
-Poor exercise performance(less than one flight of stairs)

Question 25

What are morbidity predictors in the perioperative environment?

Answer 25

-MI < 6 months ago
-Prolonged surgery > 3 hours
-Advanced age (>70)
-Complexity of resection
-Emergency surgery

Question 26

Describe the monitoring for thoracic surgery.

Answer 26

-Standard monitors: 5 lead ECG, BP Cuff, SpO2
-1-2 large bore IVs (18g preferred)
-Upper & lower Bair huggers
-Fluid Warmer
-Foley (end-organ perfusion and volume status)
-Bronchoscope (possible)
-Arterial line - on dependent
-CVP or PAC (possible)

Question 27

Why do thoracic surgery patients need an upper & lower body warmer?

Answer 27

-Incision area is quite large, so lots of skin is exposed (shoulder to mid thigh)
-Only about 20% of BSA is left to keep them warm
-Chest is opened and great vessels are exposed to cool room air temp.
-Warm them as best as you can
-Keep room warm and use fluid warmer

Question 28

Where do you place the arterial line in thoracic surgery, and why does it matter?

Answer 28

-On the dependent side (side lying down)
-Independent arm is being moved around, can give false readings if on that side.
-Changes in flow on dependent side will indicate changes to nerve bundle function (compressing nerve bundle on dependent side)
-Blood flows to dependent side due to gravity

Question 29

Where should you place a CVP/PAC if you’re placing one for a thoracic surgery?

Answer 29

Ipsilateral (same side) as the operative side.
-Risk of causing a pneumothorax (espec with subclavian approach)
-Don’t want to cause a PTX on the good lung side.

Nagelhout:
-One should remain alert to the possibility of pneumothorax with the insertion of central lines. A pneumothorax on the ventilated (nonoperative) side can lead to severe hypoxemia during OLV. If a subclavian approach to venous cannulation is planned, the insertion site should be on the same side as the planned thoracotomy.

Question 30

What are potential indications for a PA Catheter?

Answer 30

-Pulmonary HTN
-Lung transplant
-Major blood loss
-CRF (Extreme chronic renal failure)
-LVEF < 30%
-History of CHF, RHF, Pulmonary edema

Question 31

90% of PA catheters float to the ____ lung.

Answer 31

90% of PA catheters float to the right lung and will give a false low cardiac output if the right lung is the non-dependant lung.

Nagelhout:
-More than 90% of pulmonary artery catheters float into the right lung. During right thoracotomy, then, the catheter will likely be in the nondependent, collapsed lung and give a false low reading for cardiac output.

Question 32

What are Anesthetic Considerations in Lung Cancer patients (the 4 M’s)

Answer 32

1) Mass effect: Where is the mass? What is it pressing on?
2) Metabolic effects: tumor can be causing effects in the body.
3) Metastases
4) Medications: Chemo or radiation

Question 33

What mass effects are you concerned about with lung cancer?

Answer 33

-Obstructive pneumonia
-lung abscess
-superior vena cava syndrome
-tracheobronchial distortion
-Pancoast syndrome
-recurrent laryngeal nerve or phrenic nerve paresis
-chest wall or mediastinal extension

Question 34

What metabolic effects are you concerned about with lung cancer?

Answer 34

-Lambert-Eaton syndrome
-hypercalcemia
-hyponatremia
-Cushing syndrome
-syndrome of inappropriate antidiuretic hormone secretion (SIADH)

Question 35

What Metastases are you concerned about with lung cancer?

Answer 35

Particularly to brain, bone, liver, and adrenal glands

Question 36

What medications are you concerned about with lung cancer?

Answer 36

Chemotherapy-induced lung changes:
-bleomycin = pulmonary toxicity
-doxorubicin = cardiac toxicity
-cisplatin = renal toxicity

Question 37

What is a MET?

Answer 37

A unit of measurement of heat production by the body, being the metabolic heat produced by a resting-sitting subject; it is equal to 50 kilogram calories per square meter of body surface per hour.

Question 38

A MET > ___ indicates that the patient is probably ok?

Answer 38

MET > 5: they’re probably ok

MET < 5: think about metabolic needs and post op potential for complications and extubation risk, etc.

MET of 1 = big trouble. Sleeping, reclining
MET of 8 = extreme athlete

Question 39

What Regional Anesthesia procedures can be done for post-op pain management with thoracic surgery?

Answer 39

-PEC/Serratus Block
-Intercostal nerve blocks
-Thoracic Epidural
-Erector Spinae Block

Question 40

Which position is commonly used for thoracic surgery?

Answer 40

Lateral decubitus position.

Question 41

Describe positioning of a patient in lateral decubitus.

Answer 41

-Bean bag (suck air out to keep in shape)
-Cervical spine alignment - keep head in neutral position (risk of hyperextension)
-Dependent eye and ear free of pressure
-Ensure break of bed at patients iliac crest (“Flex” the bed to open up intercostal muscles)
-Axillary roll – Brachial Plexus injury is the major nerve injured. Roll maintains perfusion and prevents stretch or compression of neurovascular plexus.
-Pillows between legs: Dependent leg (peroneal nerve) and Non-dependent leg (sciatic nerve)
-Arms in neutral position - Arms less than 90 degrees
-Check genitalia

Question 42

How do you properly place an Axillary roll?

Answer 42

Placed a handbreadth below axillary. Serratus anterior.
-Want to not have pressure on neurovascular bundle.
-Roll maintains perfusion and prevents stretch or compression of neurovascular plexus. (Brachial Plexus injury is the major nerve injured!!!!!)

Nagelhout:
-A roll is placed beneath the torso just caudal to the axilla to prevent compression of the neurovascular bundle and forward rotation of the humeral head. It is important to note that, whereas this roll is commonly called an axillary roll, is better considered an axillary support roll because positioning it in the axilla may cause neurovascular compression.

Question 43

Why do you place pillows between legs?

Answer 43

-Dependent Leg: Peroneal nerve injury
-Non-dependent Leg: Sciatic nerve injury

Nagelhout:
Another pressure point of concern with the lateral position is the region near the common peroneal nerve. These pressure points are located near the fibular head of the dependent leg and the femoral head of the nondependent leg if a stabilizing strap is placed over the patient.

Question 44

What are complications associated with Lateral Positioning?

Answer 44

-Atelectasis
-Aseptic necrosis of femoral head (due to restricted blood flow. Can occur with either leg. Use egg crate to pad beneath straps).
-Brachial nerve injury
-Peroneal nerve injury (Usually dependent leg, but can be non-dependent due to straps/equipment. Will see foot drop)
-Injury to dependent eye/ear

Question 45

What do the West Zones of the lungs indicate?

Answer 45

Ventilation/Perfusion (V/Q).
-Zone 1: Alveolar > arterial > venous: Very uncommon. Restricted blood flow to that area. Pathologic.
-Zone 2: arterial > Alveolar > venous (normal)
-Zone 3: arterial > venous > Alveolar
As alveolar pressure decreases, have more blood flow.

Nagelhout:
-The vertical gradient in the lateral decubitus position is less than in the upright position; consequently, blood flow in zones 2 and 3 is less. Nevertheless, pulmonary blood flow increases with lung dependency and is greater in the dependent lung than in the nondependent lung.
-In the lateral decubitus position, gravity-related effects translate to greater compliance of the dependent lung and lesser compliance of the nondependent lung. Therefore, in the spontaneously breathing individual, more ventilation is delivered to the dependent lung.

Question 46

What are the pulmonary effects of General Anesthesia?

Answer 46

-Cephalad displacement of diaphragm (decreases FRC)
-Decrease ciliary movement
-Increased V/Q mismatch
-Increase atelectasis (Hypoventilation)

Nagelhout:
-General anesthesia creates atelectasis, which is compounded by muscle relaxants and lateral positioning, but ventilation and perfusion are further mismatched when the thorax is opened, and ceasing ventilation of one lung is the final insult.
-Fortunately, physiologic processes such as hypoxic pulmonary vasoconstriction (HPV) combat the inherent shunt, and anesthetic management is geared toward supporting those processes while fostering oxygenation through various ventilation modalities.

Question 47

What are the effects of Lateral Positioning on V/Q matching?

Answer 47

Increases V/Q Mismatch:
-Diaphragm relaxed thus abdominal contents move toward thoracic cavity.
-Mediastinal structures push on dependent lung (decreases FRC).
-Ventilation to nondependent lung.
-Perfusion to dependent lung (gravity)
-With opening of chest further increase in ventilation to nondependent lung.

Nagelhout:
-Upon opening the thorax there is an immediate decrease in resistance to gas flow in the nondependent lung, as the lung detaches from the chest wall. This causes further loss of ventilation to the dependent lung, in preference for the nondependent lung. The mediastinum also further shifts downward (compressing the dependent lung) because of loss of negative intrapleural pressure in the nondependent lung, which helped to distend it. Ventilation to the dependent lung is decreased in proportion to the displacement of the lung by the mediastinal structures. Compression of the great vessels may cause a decrease in venous return and cardiac output causing circulatory compromise.
-The less ventilated, better perfused, dependent lung contributes to physiologic shunt, as blood flows through atelectatic areas without acquiring oxygen. Although the prevalence of different zones is not as evenly distributed as diagrams would suggest, the lateral, anesthetized, paralyzed, open-chest patient does exhibit significant regional areas of ventilation and perfusion mismatching.