Respiratory Pathophysiology Flashcards
What has the most significant effect on airflow resistance?
Airway radius
Does PNS stimulation result in bronchoconstriction or bronchodilation?
Bronchoconstriction via the Vagus
Does mast cell stimulation result in bronchoconstriction or bronchodilation?
Bronchoconstriction
What sympathetic nerve causes bronchodilation?
No nerves. The beta 2 receptors are activated by circulating catecholamines, not nerves.
Cholinergic nerves endings release _____ onto ______ receptors.
Acetylcholine
M3 Receptors
What is the effect of Phospholipase C activation in airway tissues?
Causes an increase in intracellular calcium, resulting in contraction (bronchoconstriction)
What is the effect of Adenylate Cyclase/cAMP activation in airway tissues?
A decrease in intracellular calcium, resulting in dilation (bronchodilation)
What is the effect of vasoactive intestinal peptide in airway tissues?
Increase NO production, which stimulates cGMP and results in bronchodilation
There are three classes of pulmonary medications:
- Direct acting bronchodilators
- Anti-Inflammatories
- Methylxanthines
What are the two types of direct-acting bronchodilators?
Beta-2 Agonists
Anticholinergics
What anti-inflammatory drugs are used for pulmonary disease?
Corticosteroids
Cromolyn
Leukotriene Modifiers
What is the MOA of theophylline?
Its a phosphodiesterase inhibitor, which increases cAMP and decreases intracellular calcium
It also increases endogenous catecholamine release
What is the most sensitive test for small airway obstructive disease?
Forced expiratory flow at 25-75% vital capacity
What is a normal FEV1?
> 80% of predicted value (which changes with age)
What is a forced vital capacity
The volume of air that can be exhaled after a maximal inhalation
What does the FEV1/FVC ratio measure?
Compares the air expired in 1 second to the total volume of air expired.
Helps in deciphering restrictive vs. obstructive disease.
If there’s restriction, they’ll have a normal ratio. There’s less air going out because there’s less air coming in, but everything inhaled is exhaled.
If there’s obstruction, the ratio will be < 70%, meaning they’re getting a normal amount in but not all of that is being exhaled.
What is the MMEF?
Mid Maximal Expiratory Flow Rate… another name for Forced Expiratory Flow at 25-75% of VC
Reduced with obstructive disease
Normal with restrictive disease
What is the best pulmonary test of endurance?
Maximum voluntary ventilation (MVV)
Maximum volume that can be inhaled and exhaled over 1 minute
What does DLCO measure?
The ability of the alveolocapillary membrane to exchange gas
DLCO measurement is based on what law?
Fick’s law of diffusion
What is a normal DLCO?
17-25 ml/min/mmHg
What patient subsets are particularly at risk for postop pulmonary complications?
COPD
Elderly
CHF
Smoking
What procedures carry a higher risk of postop pulmonary complciations?
Surgery > 2 hrs
General Anesthesia
Aortic Surgery
Abdominal Surgery
Neuro and peripheral vascular surgery
How does a patient have to quit smoking in order to have decreased risk of postop pulmonary complications?
At least 6 weeks
Short term cessation will improve P50, but not complication rate
What are some risk reduction strategies to prevent postop pulmonary complications?
Alveolar recruitment maneuvers and PEEP
Bronchodilators/Steroids for obstructive disorders
Treat active infections
Consider not doing a general anesthetic
Teach the patient pulmonary recruitment maneuvers
What lab value indicates a high risk for postop pulmonary problems?
Albumin < 3.5, because it indicates poor nutritional status
What are alveolar recruitment maneuvers?
Peak airway pressure of 30cmH20 is required to reopen atelectic regions
Increase PIP to 40 for 8 seconds
If a patient with asthmas bronchospasms immediately following tracheal intubation, what is the most likely cause?
Vagal stimulation
What is the most common ABG finding during an asthma attack?
Respiratory alkalosis from increased Mv
What are some histamine releasing drugs that should be avoided in patients with asthma?
Morphine
Meperidine
Succinylcholine
Atracurium
What would a chest x ray look like in a patient with an asthma attack?
Hyperinflated lungs with diaphragmatic flattening
Should an HME be used in patients with asthma?
It may benefit patients with exercise-induced asthma
What dose of IV lidocaine suppresses airway reflexes?
1-1.5 mg/kg
Why can’t asthmatics have hemabate?
It mimics the actions of pro-inflammatory prostaglandins