Asthma

Question 1

12 year old dental tx and has asthma, how do you proceed?

Answer 1

H&P - ask about asthma, particular triggers, ER visits, intubations, recent PFTs (be able to describe spirometry, FEV1, FEV1/FVC), how often do you use an inhaler

• What meds?
• Get an idea of how well controlled
• Who is the MD, preop consult needed?

Question 2

What is asthma?

Answer 2

A type of obstructive respiratory disease characterized by dyspnea and expiratory wheezes secondary to airway narrowing from smooth muscle constriction, increased airway edema, mucous release and hyperactivity

Question 3

What are the most common signs and symptoms of asthma?

Answer 3

Dyspnea, cough, wheezing

Question 4

How is asthma classified?

Answer 4

Extrinsic (allergic, juvenile onset, easier to tx) vs intrinsic (non-allergic, adult onset, follows severe respiratory illness)

or

Mild Interm - symptomatic <2x/week, night sympt <2x/month, normal PFTs
Mild Pers - >2x/week, night >2x/month, normal PFTs
Mod Pers - Daily, night >1x/week, FEV1 60-80%
Severe Pers - continual symptoms, frequent night, FEV 1 <60%

Question 5

What are your typical asthma meds?

Answer 5

Beta 2 agonist - albuterol and salmeterol that mediate bronchodilation
Steroids - long term control, example Fluticasone (Advair = salmeterol and fluticasone)
Anticholinergics - ipatropium bromide, good for pts that can’t tolerate beta 2 agonists, minor bronchodilation decreases mucus gland hypersecretion, also helps with vagally mediated bronchospasms
Cromolyn Na+ - blocks mast cell degranulation
Phosphodiesterase inhibitors - Theophylline, used for hard to control patients, minor bronchodilation but increase mucocillary clearance
Leukotriene receptor antagonists - blocks leukotriene receptor, activation of the receptor causes bronchial constriciton, increased mucous secretion, and increased permeability, example is montelukast

Question 6

What are PFTs?

Answer 6

Pulmonary function tests

Question 7

What are FEV1 and FVC?

Answer 7

Forced expiratory volume in 1 second
Forced vital capacity - Volume of lungs from full inspiration to forced maximal expiration. It is reduced in restrictive disease, and in obstructive disease if air trapping occurs.

Question 8

What is normal FEV1/FVC?

Answer 8

70%, if less than that there is obstruction

Question 9

What is the methacholine challenge?

Answer 9

Give methacholine, FEV1 should drop by at least 20% due to constriction and then administer albuterol which should lead to resolution.

Methacholine is non-selective muscarinic receptor agonist in the parasympathetic nervous system

Question 10

What are anesthetic considerations for asthma?

Answer 10

• Is patient in optimal condition? visits to ER, hospitalized, intubated, active wheezing, use of rescue inhaler
• Ideal to have resolutions of any recent exacerbation
• Recent PFTs
• Continue meds, have inhaler with patient, preop dose
• CXR? you will see hyperinflation from autopeep/air trapping, flattened diaphragm
• Increased risk for bronchospasm (inciting factors include stress, pain, stimulation)
• Anxylotyics good
• Propofol, ketamine, inhalational anesthetics are great…bronchodilation
• Warm, humidified air

Question 11

You get a bronchospasm…what do you do?

Answer 11

• s/s include increased peak pressure (amount of pressure on ventilator needed to deliver tidal volume) and decreased tidal volume, decreased sats with either increased wheezing or decreased airflow
• Increase depth of anesthesia w/ volatile
• B2 agonists like albuterol
• 0.3mg of epi IV or IM
• racemic epi 2-2.5mg epi diluted in 10cc NS through tube
• Other bronchodilators (propofol and ketamine)
• If not tubed then secure airway…jaw thrust, bag mask valve, tube