Asthma

Question 1

What are the asthma stats?

What is it attributed to?

Answer 1

• One of the most common chronic conditions worldwide
• 300 million people globally
  
  • Increasing in developing countries
• attributed to air polution
• genetic and environmental components
  
  • strongly influenced by genetics

Question 2

What does asthma do to the airways?

Answer 2

• Chronic inflammatory disorder of the airways characterized by increase responsieness of the tracheobronchial tree to a variety of stimuli
• Airways are enflamed, edemetous, and hypersensitive to irritants
• Severe cases will have airway wall thickening
  
  • increased epithelium, submucosa, and smooth muscle tone
• Reversible expiratory flow obstruction
  
  • from hyperactivity and constriction
  • degree varies over time; dynamic disease

Question 3

What are the symptoms of Asthma?

Answer 3

• Wheezing
• breathlessness
• chest tightness
• cough (night and early am)
• tachypnea
• prolonged expiration phase
• fatigue
• variable airflow obstruction that is reversible

Question 4

What are asthma triggers?

Answer 4

• allergens
• drugs
  
  • aspirin
  • NSAIDS
• infections
• exercise
• emotional stress

Question 5

What is the pathophysiology of asthma?

What are the inflammatory mediators?

Answer 5

• Activation of inflammatory cascade releases mediators from mast cells that interact with receptors in bronchial wall and the autonomic nervous system to cause bronchoconstriction
• Inflammatory mediators:
  
  • histamine
  • leukotrienes
  • prostaglandins
  • substance P

Question 6

What cells infiltrate the airway mucosa?

What does this cause?

Answer 6

• Cells:
  
  • eosinophils
  • neutrophils
  • mast cells
  • T lymphocytes
  • leukotrienes
  • basophils
• Causes bronchial edema and thickening of the airway

Question 7

How is Asthma diagnosed?

Answer 7

• By looking at physical symptoms and pulmonary function tests
  
  • baseline compared to after bronchodilator therapy
  • if improvement is seen, asthma is indicated

Question 8

What would you expect to see on the PFT of a pt with asthma?

Answer 8

• Decreased FEV1 and FEF_25-75% (Maximum mid expiratory flow rate (MMEF))
  
  • direct measurement of expiratory flow rate obstruction
  • extent of decrease reflects the severity of expiratory obstruction
• During asthma attach FEV₁ <35% and MMEF <20%
• Flow volume loop show a characteristic downward scooping of the expiratory limb

Question 9

What is considered mild to moderate asthma?

what would an ABG look like?

Answer 9

• FEV1 <80%
• PaO2 and PaCO2 normal

Question 10

What does severe asthma look like on PFTs?

ABG?

Answer 10

• FEV2 < 25%
• PaO2 may be < 60 mmHg and hypercarbia may develop
• respiratory muscle fatigue

Question 11

What does PaCO2 usually do with a pt with asthma?

Answer 11

• PaCO2 often decreases as a result of hyperventilation, a neural reflex to bronchoconstriction

Question 12

What would you expect a CXR to look like for a pt with asthma?

Answer 12

• hyperinflation of the lungs
• hilar vascular congestion from mucous plugging and pulm hypertension if disease is severe

Question 13

What is the pharmacologic approach for pts with asthma?

How is this done?

Answer 13

• prophylactic approach; treat underlying inflammation
  
  • as opposed to just treating bronchospasm
• Inhaled or systemic corticosteroids
  
  • decreased bronchial mucosa inflammation and hyper-responsiveness
  • advair
• Cromolyn
• Leukotriene inhibitors
• Methylxanthines- phosphodiesterase inhibitors

Question 14

What are the rescue medications used for a severe asthma attack?

Answer 14

• Beta-2 adrenergic agonists- albuterol, terbutaline
  
  • B2 receptor activation of adenylate cyclase with increased cAMP concentrations and bronchodilation
  • SNS side effects: tachycardia, dysrhythmias, potassium shits
• Anticholinergic drugs- ipratropium
  
  • blocks muscarinic recepors = bronchodilation
  • less effective than B2 in asthmatics
  • can prolong effects of B2 inhalors

Question 15

What should we assess pre-induction for a patient with asthma?

Answer 15

• H&P
  
  • breath sounds
• PFTs before and after bronchodilator therapy for major surgery
  
  • FEV₁/FVC should be > 70-80% expected or personal best prior to surgery
  • FEV₁/FVC <60% - risk for pulmonary morbidity
• CXR- looking for changes over time
• ABG- non necessary unless questionable oxygenation/ventilation prior to elective surgery
• Continue current asthma medications into peri-op period

Question 16

Benzos vs opioids in a pt with asthma?

Answer 16

• benzos are a good choice b/c anxiety can precipitate bronchospasm
• opioids- consider resp depressant effect

Question 17

How can you prevent bronchoconstriction perioperatively?

Answer 17

• Pre-op bronchodilators- albuterol before induction
• pre-op steroids
  
  • If starting inhaled staroids, should start 48 hrs prior to surgery
  • hydrocortisone 100 mg q 8 hours on day of surgery if FEV1 <80%
    
    • may need stress dose steroids

Question 18

What are the goals for GA?

Regional?

Answer 18

• General should be designed to:
  
  • depress airway reflexes
    
    • LMAs are better tolerated, less airway manipulations
    • IV lidocaine 1-1.5 mg/kg, and opioids
    • LTA- topical lidocaine
    • propofol (no metabisulfites) and ketamine best
  • avoid hyperactivity
  • treat bronchoconstriction
  • avoid histamine release
• consider regional, to avoid airway issues, but remember to avoid stressing them

Question 19

What VA and NMB would you use for pts with asthma?

Answer 19

• Sevo and halothane are less pungent; less coughing to trigger bronchospasm
  
  • use high concentration >1.5 MAC for dilation and bronchial reflex inhibition
  • need strong CV system for this
• Avoid NDMRs that release histamine
  
  • atracurium
  • mivacurium
  • d-tubo
• Anticholinesterase:
  
  • neostigmine ok if given with anticholinergic

Question 20

Why would you not want to use thiopental (if it was available) in an asthmatic pt?

Whats the concern with propofol?

Answer 20

• releases histamine
• Propofol- generic has sulfites that can cause reaction

Question 21

What is the induction drug of choice for the asthmatic pt?

Answer 21

• Ketamine for bronchodilator effects
• stimulates secretions, so give with anticholinergic

Question 22

Which opioids should be avoided in asthmatics?

non opioid pain meds?

Answer 22

morphine

meperidine

nsaids

asa

Question 23

Which VA can irritate the airway?

Answer 23

Isoflurane

Desflurane- really bad

Question 24

How should you emerge a pt with asthma?

Answer 24

• goal for a smooth emergence
• Possibly extubate deep if appropriate

Question 25

how can you treat intraoperative bronchospasm?

Answer 25

* attach albuterol to T-piece of ETT and give dose

Question 26

How do you want to manage fluids in a pt with asthma?

Answer 26

liberal hydration to decrease viscosity of secretions

Question 27

How do you want to ventilate an asthmatic patient?

Answer 27

* decreased RR 8-10 bpm * need adequate exhalation times * Prolong I:E ratio * Increase TV to maintain normal PaCO2 * Avoid excessive peak airway pressures (\>40 cmH2O)

Question 28

What is the differential diagnosis of intraoperative wheezing?

Answer 28

* foreign body (gastric tube in lung) * partially blocked/kinked ETT * light anesthesia * aspiration * endobronchial intubation * pneumothorax * pulmonary embolus * pulmonary edema * **acute exacerbation of asthma**

Question 29

What do you do if your pt bronchospasms during anesthesia?

Answer 29

* Administer 100% O2 * deepen the level of anesthesia with a VA or IV drug * administer B2 agonist * in severe cases administer epi IV * infusion 2-8 mcg/min * SQ 0.3-0.5 mg q 20-30 min * consider IV corticosteroids * 1-2 mg/kg of cortisol * consider IV aminophylline

Question 30

Would you take a pt who is actively wheezing to the OR?

Answer 30

NO!! You should avoid this at all costs!! Especially if the procedure is elective