Obstructive Lung Disease

Question 1

What are the risk factors for emphysema/bronchitis (COPD)?

Answer 1

• Cigarette smoking/passive smoke
• industrial exposure (coal, textiles, gold mining, asbestos)
• ambient air pollution
• alpha₁-antitrypsin deficiency
  
  • only known genetic abnormality that leads to COPD
  • accounts for <1% of cases

Question 2

What is the definition of COPD?

Chronic bronchitis?

Answer 2

• COPD- A preventable and treatable disease characterized by progressive pulmonary airflow limitations, not fully reversible and an abnormal inflammatory response to noxious gases or particles
• Chronic bronchitis- persistent product cough for at least 3 months out of the year for at least two consecutive years

Question 3

How is COPD different from Asthma?

Answer 3

The obstruction of COPD is not reversible (or incompletely reversible) by bronchodilators

Question 4

What is the pathophysiology of COPD?

Answer 4

• Cell death and destruction of the alveoli is caused by impaired lung parenchyma and the toxic actions of inflammatory cells (macrophages and neutrophils)
  
  • this leads to fibrosis and increased mucous production
• Dediorioration in elastic recoil of the lungs and small airway collapse
• Enlarged airspace with decreased diffusion capacity
  
  • leading to hypoxia and hypercarbia

Question 5

What three things cause airway collapse in a pt with COPD during exhalation?

Answer 5

• Deterioration in the elastic recoil causes early small airway collapse
• Decreased rigidity of bronchiolar walls
• turbulent airflow through narrowed bronchioli lowers the pressure inside the bronchioles, favoring collapse

Question 6

What are the physical S/S used to diagnose COPD?

Answer 6

• Chronic cough
• bronchitis leading to chronic productive cough
• progressive exercise limitation
• dyspnea/Orthopnea (dyspnea when lying flat)
• sputum discoloration (infection)
• wheezing

Question 7

What kind of testing is used for diagnosis and severity classification of COPD?

Answer 7

• Spirometry (PFT)
  
  • decreased FEV1/FVC ratio less than 70%
  • decreased FEF 25-75% (forced expiratory flow)
  • Increased RV and normal to increased FRC and TLC
• CXR
  
  • hyperinflation
  • flat diaphragm
  • vertical cardiac silhouette
• ABG
  
  • Blue bloaters (chronic bronchitis)
    
    • PaO2 <60 mmHG
    • PaCO2 >45
  • Pink puffers (emphysema)
    
    • PaO2 usually higher than 60
    • PaCO2 normal

Question 8

How is COPD staged?

Answer 8

• **All stages have FEV₁:FEV ratio <70%
• 0: At risk
  
  • normal spirometry but chronic cough or sputum
• 1: Mild COPD
  
  • FEV₁ >80%
• 2: Moderate COPD
  
  • 50% <fev>1 &lt;80%</fev>
• 3: Severe COPD
  
  • 30% < FEV₁ <50%
• 4: Very severe COPD
  
  • FEV₁ < 30%

Question 9

What are some differences between an emphysema patient and Bronchitis patient?

Answer 9

• Emphysema
  
  • thin
  • anxious
  • dyspnea
  • accessory muscles
  • few secretions
  • markedly diminished breath sounds
  • CXR- hyperinflation and flattened diaphragm
• Bronchitis
  
  • overweight
  • cyanosis, dusky appearance
  • cough
  • copious secretions
  • diminished breath sounds
  • CXR- increased bronchovascular markings

Question 10

How is COPD treated?

What are the goals of treatment?

Answer 10

• Goals to relieve the symptoms and slow progression of the disease
  
  • stop smoking!
  • supplemental O2 if PaO2 < 55 or HCT > 55 or developing cor pulmonale
    
    • 2L NC at home
    • O2 is most effective therapy for COPD

Question 11

What would you note on a pre-op history and physical of a pt with COPD?

How could you optimize them for anesthesia?

Answer 11

• History and Physical:
  
  • Exercise intolerance
  • chronic cough
  • dyspnea
  • absent breath sounds or wheezing
  • prolonged exhalation
• Pre-op optimization:
  
  • smoking cessation
  • bronchodilation
  • eliminate infection

Question 12

What are the problems smoking causes?

Answer 12

• decreased ciliary motility and increases sputum production
• decreases pulmonary immune function
• causes airway reactivity and obstructive disease
• most prevalent risk factor associated with post-op morbidity
• 2-6x risk of developing post-op PNA
• best benefit to surgery is to quit 2 months pre-op
  
  • 24 hour abstinence may decrease carboxyhemoglobin level to normal
  • but may increase risk of post-op pulmonary complications- may have increase in sputum production, but still worth having them stop!
• impairs wound healing

Question 13

What are the changes seen with smoking cessation

Answer 13

• 12-24 hours Carboxyhgb drops to 1%
• 2-6 weeks for improved ciliary function
  
  • normalization of immune system at least 6 weeks
• 8 weeks reduction in post-op pulmonary complications

Question 14

How can we treat COPD patients to dilate airway and prevent bronchospasm?

Answer 14

• sympathomimetics
  
  • produce cAMP –>bronchodilation
  • Ex: albuterol, terbutaline–selective B2 agonists
• PDE inhibitors
  
  • inhibit breakdown of cAMP
  • Aminophylin
• Steroids
  
  • decrease mucosal edema
  • Ex. inhaled steroids; not used accutely, but can help edema
• Cromolyn
  
  • mast cell stabilization and inhibits histamine release
• **combination therapy improves FEV1, dyspnea, and exacerbations
• These pts should always get flu and PNA shot

Question 15

What other pre-op treatments should we consider for pts with COPD?

Answer 15

• No smoking after midnight- do decrease COHgb
• antibiotics if evidence of respiratory infection
• O2 for hypoxia and/or evidence of increased pulmonary vascular resistance–do not discontinue for transport
• bronchodilators
• hydration

Question 16

What are some things you should educate the pt with COPD on before surgery?

Answer 16

• Post op complications:
  
  • atelectasis
  • hypercapnea
  • hypoxemia
  • retention of secretions
  • bronchospasm
• Explain need for possible post-op ventilation
• educate about splinting and incentive spirometry

Question 17

What is the goal with anesthetic management of COPD patients?

How might we achieve this?

Answer 17

• Goal: Minimize the risk of postop respiratory failure
• VA will blunt airway reflexes and bronchoconstriction
  
  • consider the CV effects
• Regional anesthesia may be preferred for surgery of extremeties and lower abdomen (not above T6)
  
  • dont want to inhibit accessory muscles that they rely on
  • good for cysto and gyno procedures
• Careful use of opioids- avoid resp depression

Question 18

How would you manage GA for a pt with COPD?

Answer 18

• IV opioids and lidocaine to attenuate for DVL and decrease reactivity
• No specific agent is ideal, consider comorbidities
  
  • VA produce bronchodilation and are rapidly eliminated
  • Short acting NMB- want them to have adequate muscle strength, avoid histamine
  • careful use of opioids
• Humidification and low gas flow

Question 19

How would you venitlate a pt with COPD?

Answer 19

• Adjust TV to keep airway pressures < 40 cm H2O; 6-8 ml/kg
• Slow rate of 6-10 bpm
• allow sufficient time for exhalation
• be aware of pulmonary barotrauma
• consider baseline PaCO2; may not want to correct to “normal” (may result in metabolic alkalosis
• spontaneous ventilation may result in hypercapnia

Question 20

What should you consider when emerging a pt with COPD?

Answer 20

• Post operative respiratory status is the priority issue
• adequate pain control for pain-free breathing and coughing
  
  • avoid resp depression
• May require post op ventilation
  
  • guide weaning with ABGs

Question 21

What are the advantages and disadvantages of N2O in a pt with COPD?

Answer 21

• Advantages
  
  • decrease dose on VA
  • quick on, quick off- not really important anymore because agents (sevo, des) are so fast
• Disadvantages
  
  • potential to diffuse into airspaces quicker than nitrogen can exit, possibly causing tension pneumothorax or bullae rupture
  • b/c it is given in concentrations of 50-70%, it limits how much O2 can be delivered
  • DO NOT give N2O to a patient with Pulmonary hypertension

Question 22

What is a bullae?

Answer 22

a bubble like cavity full of fluid or air

Question 23

Which COPD patients will most likely need post op ventilation?

Post-op ventilation should maintain PaO2 at ______ and pH at ______

Answer 23

• Patients with a pre-op FEV₁/FEV ratio less than 0.5 or with a pre-op PaCO2 greater than 50 will likely need post-op ventilation
• Post-op ventilation should maintain PaO2 between 60-100 and PaCO2 to maintain pH 7.35-7.45
• **post-op ventilation is not a complication, it should be expected and they should be warned

Question 24

What should be considered post-op to prevent pulmonary complications?

Answer 24

• Surgical site may affect respiratory dept
• Encourage lung expansion maneuvers to decrease the risk of atelectasis by increasing lung volumes
  
  • deep breathing
  • Chest PT
  • IS
  • pain control