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What type of testing device is used to monitor asthmatics?
Peak flow meters (pts blow as hard & fast as they can)
What are the indications for spirometry?
- Determine presence, location & severity of disease
- Progression & prognosis
Amount of air contained in the fully expanded lung.
total lung capacity
Maximum amount of air that can be exhaled.
What does spirometry measure?
DIFFERENT volumes of air involved in ventilation
Volume of air that enters the lung during a normal breath.
Amount of air remaining after maximum expiration.
Indicates degree of lung and chest expansion, measure total amount of air that a pt can blow out as fast as possible after inhaling as deep as possible, is a good indicator of pt effort, measures VOLUME.
forced vital capacity (FVC)
Indicates patency of large airways, measure amount of air forcefully blown out during the 1st second of effort, indicates both large and small airway function, measures VOLUME.
forced expiratory volume (FEV1)
Percentage of FVC that occurs in the 1st second of the effort, reduced ratio may imply airway obstruction, directly affected by height and age, may also be affected if FVC is increased/decreased due to occupation or environment.
May also be called maximal mid-expiratory flow rate (MMEF), indicates patency of small airways, measures flow generated during the mid-portion of the forced expiratory maneuver, least effort dependent, measures FLOW.
forced expiratory flow (FEF 25-75)
Indicates large airway patency, measures the highest flow that can be generated by the pt forcefully blowing after fully inflating the lungs, VERY EFFORT DEPENDENT, measures FLOW.
peak expiratory flow (PEF)
When should you consider using additional PFTs to assess lung function/capacity?
- interval change
- change demonstrated w/ a maneuver (exercise/methacholine challenge, post bronchodilators)
Which test can be used to dx lung disease (restrictive/obstructive)?
What kind of lung disease causes a decrease in vital capacity (lung volume), but does NOT decrease FEV:FVC ratio?
What kind of lung disease causes a marked decrease in FEV1:FVC ratio (vital capacity may be normal or decreased)?
What are some restrictive disorders that affect lung function/capacity?
- neurological d/o (gullain barre- attack on peripheral NS, starts @ toes and works up)
- tumors & cavitations (space occupying lesions)
- fibrosis (sarcoidosis)
Describe the spirometry lung pattern seen in restrictive defects.
- FEV1/FVC >80
- decreased FVC
Describe the spirometry lung pattern seen in obstructive disorders.
What are some obstructive disorders that affect lung function/capacity?
- asthma (most common)
- chronic bronchitis
- cystic fibrosis (NOT RESTRICTIVE!)
What special test reflects the ability of the lung to transfer gas across the alveolar/capillary interface? What is this test useful in evaluating for?
- single breath carbon monoxide (diffusing capacity DLCO)
- useful in evaluating diffuse infiltrative lung disease/emphysema
What does total pulmonary diffusing capacity depend on?
- diffusion properties of the alveolar-capillary membrane
- amount of hemoglobin occupying the pulmonary capillaries (diffusing capacity needs to be corrected for Hgb)
What conditions cause increased & decreased diffusing capacity DLCO?
- Increased: pulmonary hemorrhage, CHF, asthma (due to increased pulm capillary blood volume)
- Decreased: emphysema, diffuse infiltrative lung disease, Pneumocystis
Bronchial provocation testing that aids in the evaluation of suspected asthma, when baseline spirometer is normal (eval for unexplained cough).
Bronchial provocation testing that uses agents which cause bronchial smooth muscle constriction at lower doses than non-asthmatics.
inhaled methacholine/histamine challenge (if FEV1 falls greater than 20% it is a positive test)
Which test can assess lung function by analyzing pH, partial pressure of O2 and parital pressure of CO2?
arterial blood gas
Name the 2 categories that ABGs look at.
- acid-base balance
Which inexpensive, noninvasive test monitors hemoglobin O2 saturation?
The accuracy of oximetry can be reduced by what conditions?
- severe anemia (<5 g/dL Hgb)
- increased presence of methemoglobin, carboxy Hgb, intravascular dyes, motion artifact
- lack of pulsatile arterial blood flow (HOTN, hypothermia, cardiac arrest, simultaneous use of BP cuff, cardiopulmonary bypass)
If pCO2 is the cause for pH imbalance, what is the cause?
If HCO3 is the cause for pH imbalance, what is the cause?
How long must the duration of a cough be in order to be considered chronic or persistent cough?
duration >8 weeks (variety of cough that usually prompts pts to seek medical care)
What is the duration of an acute cough?
up to 3 weeks (usually viral URI)
What is the duration of a subacute cough?
What are the complications that pts present with who are experiencing a chronic/persistent cough?
- feeling that something is wrong (most common)
- self conscious
- lifestyle changes
- musculoskeletal pain
- excessive perspiration
- urinary incontinence (& host of others)
What are some additional physiologic symptoms of chronic cough due to high intrathoracic & intra-abdominal pressures achieved?
- cough syncope
- cardiac dysrhythmias
- subconjunctival hemorrhage
- inguinal herniation
- gastroesophageal reflux
What is the mainstay of treatment for acute cough?
nonspecific antitussive therapy