Anesthesia for Thoracic Surgery Flashcards
What are some possible preoperative symptoms associated with thoracic surgery?
Coughing/wheezing Hemoptysis Weight loss (advanced cancer) Dyspnea Pleuritic chest pain (problem spread to pleura) Horner syndrome Hoarseness (RLN Damage)
What is Horner’s syndrome?
Also known as oculocephalic palsy it is the combination of ptosis, meiosis and anhydrosis on the ipsilateral side.
Ptosis = drooping eyelid
Meiosis = pupil construction
Anhydrosis = lack of sweating
What are some preoperative tests that may provide important information for patients undergoing thoracic surgery?
PFTs
Radiologic imaging
Cardiac assessment
Baseline ABG on RA
If a patient appears for thoracic surgery that has a Cushing’s appearance they may also have what syndrome?
Paraneoplastic syndrome
-Hormonal or other secretions from a tumor
What is the difference between resectability and operability?
Resectability refers to the tumor stage.
Operability refers to the patient’s health
Most thoracic surgical procedures are done under what type of anesthetic?
General
Why is positioning particularly important for patients undergoing thoracic procedures?
Surgical access
Ease of ventilation (VQ Mismatch)
Potential for pneumothorax
Possibility of nerve damage
What is VATS?
Video assisted thoracoscopic surgery
How does ventilation change between and anesthetized and the awake patient in the lateral decubitus position?
In the awake (spontaneous ventilation) patient VQ matching is normal
In the anesthetized patient VQ mismatching occurs at the upper lung is ventilated more and the lower lung is less compliant
When the chest cavity is open what happens to pleural pressure?
Normal negative pleural pressure is lost and the lung will normally collapse
Spontaneous ventilation with an open pneumothorax in the lateral position results in what two negative phenomena?
Mediastinal shift
Paradoxical respirations
How can we overcome mediastinal shift and paradoxical respiration?
By positive pressure ventilation during general anesthesia and thoracotomy
Paradoxical respirations and mediastinal shift can cause what to progressive problems?
Hypoxemia and hypercapnia
Intentional collapse of the lung on the operative side facilitates most thoracic procedures, but greatly complicates anesthetic management. Why?
When the collapsed lung continues to be perfused and is deliberately no longer ventilated the patient can develop a large right to left intrapulmonary shunt
What effect does one lung ventilation have on the alveolar to arterial oxygen gradient?
What is the end result?
It widens the alveolar to arterial oxygen gradient which often results in hypoxemia
How is this alveolar to arterial gradient difference overcome naturally by the body?
Blood flow to the non-ventilated lung is decreased by Hypoxic pulmonary vasoconstriction (HPV)
What factors are known to inhibit HPV and thus worsen the right to left shunt?
Hypocapnia Vasodilators & Ca2+ Channel Blockers Inhalational anesthetics PEEP High PVR (Pulmonary infection) Hypothermia Extremes of mixed venous PO2 Extremes of PA pressures
What would a decrease in blood flow to the ventilated lung cause?
It would counteract the effect of HPV by indirectly increasing blood flow to the collapsed lung
What factors could possibly decrease blood flow to the ventilated lung?
- High mean airway pressures due to increased PEEP
- Low FiO2
- Vasoconstrictors (greater effect on normoxic than hypoxic vessels)
- Intrinsic PEEP that develops due to inadequate expiratory times.
What is the “3-legged stool?”
A pre-thoracotomy respiratory assessment that includes:
- Respiratory mechanics
- Cardiopulmonary reserve
- Long parenchymal function
When assessing respiratory mechanics the general cut off for success is a PPO greater than what percent?
PPO > 40%
What is a normal PPO?
80 to 100% predicted
What is FEV1?
Forced expiratory volume (1 sec)
What is the difference between volume and capacity?
Volume = directly measured Capacity = Some of 2+ volumes
What are some absolute indications for one lung ventilation?
- Contamination
- Control of distribution of ventilation
- Airway fistula
- Need for differential ventilation - Bronchoalveolar lavage
What are some relative indications for one lung ventilation?
Thoracic aneurysm Pneumonectomy Upper lobe procedures Thoracoscopic surgery (usually requires) Esophagectomy (Iver Louis) Other lung resections Transplant (Bilateral vs single)
How can one lung ventilation lead to hypoxemia?
Hypoventilation Shunt Diffusion Inadequate FiO2 VQ mismatch Anemia
What can we do to manage hypoxemia with one lung ventilation?
- Maintain minute ventilation
- Decreased tidal volume
- Increased respiratory rate - CPAP to non-ventilated lung
- PEEP to ventilated lung (avoid auto-PEEP)
Extreme: Have surgeon clamp pulmonary artery or reinstate two lung ventilation
In general, thoracic procedures are better tolerated on which side?
Left sided procedures because the right lung is bigger
What are three techniques used to facilitate one lung ventilation?
- Double lumen bronchial tube (R vs L)
- Use of a single lumen tracheal tube with a bronchial blocker
- Endobronchial intubation with a single lumen tube
Sizing of double lumen tubes depends on what?
Patient’s height
What are some advantages to double lumen tubes?
Relative ease of use
Ability to suction the non-ventilated lung
Ability to reposition
Ability to use CPAP
What are some disadvantages to double lumen tubes?
- Can be challenging to place
- Size limitations
- Need to exchange if post-op ventilation is required
What are some common sizes of double lumen tubes for men and women?
Men = 39F (occ. 41) Women = 37F (occ. 35)
At what point during placement is the double lumen tube rotated?
DLT is rotated once the bronchial cough is past the cords
What color is the bronchial cuff normally?
Bronchial = Blue
How is proper placement of a DLT verified?
With a (pediatric) fiberoptic scope
What is the average depth of a DLT?
29cm
Which sided tubes are used most often?
Left (easier placement)
All double lumen tube’s share what characteristics?
- A longer bronchial lumen
- Shorter tracheal lumen
- Preformed curve that allows preferential entry into the bronchus
- A bronchial and tracheal cuff
The average adult trachea is how long?
11 to 13 cm
What must a right-sided bronchial tube have?
A slit in the bronchial cuff for ventilating the right upper lobe
After proper tube placement is confirmed and the patient is repositioned for surgery what must then be done?
Reconfirm tube position
Malpositioning of a double lumen tube is usually indicated by what?
Poor lung compliance and low exhaled tidal volumes
A problem with left sided DLT placement is usually related to what three possibilities?
The tube is too deep
Not deep enough
It entered the wrong bronchus
What is the maximum amount of air that should be inflated into a bronchial cuff?
2cc of air
When confirming placement of a DLT where should FFOB be placed first?
In the tracheal lumen
What are some advantages of bronchial blockers?
- *1. No need for tube exchange
2. Easier intubation
3. Some tubes can enable use of CPAP
What is the major disadvantage of a bronchial blocker?
The “blocked” lung collapses slowly and sometimes incompletely
When a DLT is in the correct position what can you expect to see on the ipsilateral and contralateral sides when the bronchial tube is clamped?
Ipsilateral (side clamped):
- Breath sounds disappear
- Hemithorax does not move
- No moisture exchange in tube
Contralateral (ventilated side):
- Breath sounds remain
- Hemithorax rises and falls
- Changes in respiratory gas moisture
- Bag compliance expected for one lung ventilation
In what patient population is endobronchial intubation most often used for one lung ventilation?
Pediatrics
What are the ventilation goals for one lung ventilation?
- 6 to 8 mL/kg to ventilated lung
- aim for peak pressure < 25 cmH2O
- Typically use PC
- (+/-) PEEP
What are some major complications of DLT’s?
- Hypoxemia
- Traumatic laryngitis
- Tracheobronchial rupture from over inflation of the bronchial cuff
- Inadvertent suture and of the tube to a bronchus during surgery
What is the ratio of fractional blood flow between the dependent and non-dependent lungs in two lung ventilation vs one lung ventilation?
Two-Lung:
Dependent = 60. Non-dependent = 40
One-Lung:
Dependent = 77.5 Non-dependent = 22.5
Lung resections are usually carried out for the diagnosis and treatment of what three causes?
- Lung tumors (most common)
- Pulmonary infections
- Bronchiectasis
What are some examples of procedures that can be done as VATS?
Lung resection
Pericardial window
Esophageal surgery
Pleurodesis
What two factors increase the incidence of arrhythmias during thoracic procedures?
Increased age
Increased amount of pulmonary resection
What is post pneumonectomy syndrome?
Mediastinal shift which results in stretching and compression of tracheobronchial tree and esophagus following pneumonectomy
- Shortness of breath (main symptom)
- More common after left pneumonectomy
- Treated with saline filled implants in vacant hemithorax
When gaining central venous access during a thoracotomy the central venous line is preferentially placed on which side?
The side of the thoracotomy
Post pneumonectomy pulmonary edema is most common when….
- A right pneumonectomy was performed
- Aggressive periop Fluid resuscitation
What happens to venous return when the chest is opened?
Venous return decreases when the chest is open because negative pleural (intrathoracic) pressure is lost on the operative side
Excessive fluid administration in the lateral decubitus position may promote what syndrome?
Lower lung syndrome
What is lower lung syndrome?
Gravity dependent transudation of fluid into the dependant lung
- Increases intrapulmonary shunting
- Promotes hypoxemia
- Collapsed lung is prone to edema following reexpansion
The greatest risk of one lung ventilation is _____
Hypoxemia
What to post operative effects are common following atelectasis from surgical compression of the lungs and shallow breathing due to incisional pain?
Hypoxemia and respiratory acidosis
What is the presentation of a bronchopleural fistula?
Sudden large airleak from the chest tube that may be associated with an increasing pneumothorax and partial lung collapse
Acute herniation of the heart into the operative hemithorax can occur following a radical pneumonectomy. How will this present on the left versus the right?
Herniation into the LEFT hemithorax:
- hypotension
- ischemia
- infarction
Herniation into the RIGHT hemithorax:
- hypotension
- elevated CVP
How is massive hemoptysis usually defined for patients undergoing lung resection?
> 500-600 mL blood loss from tracheobronchial tree within 24hrs
Tracheal resections are commonly performed for what reasons?
Tracheal stenosis
Tracheal mass/tumor
Extrinsic airway compression
Rarely congenital abnormalities
What is the most valuable preoperative assessment for patients undergoing tracheal resection?
Flow volume loops confirm the location of the obstruction and aid the clinician in evaluating the severity of the lesion
What type of anesthetic is usually necessary for patients undergoing a tracheal resection?
TIVA
Jet or cross-table ventilation
What is the goal of lung volume reduction surgery (LVRS)?
To remove severely emphysematous lung tissue
Where should the pulse ox and blood pressure cuff be placed for a patient undergoing a mediastinoscopy?
BP Cuff = Left
Pulse-Ox = Right
Why must the pulse ox be placed on the right side and the blood pressure cuff on the left for patients undergoing a mediastinoscopy?
Compression of the Innominate artery
What is another name for mediastinoscopy?
Chamberlain procedure
What are some potential complications associated with the Chamberlain procedure?
- Reflex bradycardia
- Excessive hemorrhage
- Cerebral ischemia (compression of Innominate)
- Pneumothorax
- Air embolism
- RLN or Phrenic nerve damage
When is lung transplantation indicated?
End stage lung disease or pulmonary hypertension
What are some common comorbidities associated with end-stage lung disease?
Liver disease (Alpha-1 antitrypsin deficiency) Right heart failure
What is important to remember in terms of PA and arterial pressures during lung transplantation?
Yellow can’t be > Red
Pulmonary Artery pressure should not exceed Arterial pressure
What are some important considerations for postoperative analgesia?
- Epidurals are important as part of pain control after major thoracic surgery (esp with chronic pain pts)
- Multimodal analgesia (attack it from different angles) (IV narcotics, NSAIDs, Local)
What two factors will necessitate cardiopulmonary bypass during transplantation of one lung?
Persistent arterial hypoxemia (SpO2 <88%)
Sudden increase in PA pressures
What is superior vena cava syndrome?
The result of progressive enlargement of a mediastinal mass and compression of mediastinal structures particularly the vena cava.
-Associated with severe airway obstruction and CV collapse on induction
