Pulmonary Function Tests (PFT) Flashcards
indications of PFT
- Respiratory sign and symptoms
- monitoring of patient with lungs disease for response to treatment and disease progression
- investigating of further complications
- surveillance of pulmonary transplant
- investigating patient at risk of pulmonary disease
- preoperative evaluation
contraindication of PFT
1.myocardial infraction within previous month
2. abdominal, eye, thoracic surgery or aneurysm
3.unstable angina
4. hemodynamic unstability
5. pneumothorax
6. recent hemoptysis
TLC (Total Lung Capacity)
the total amount of air in the lungs at maximal inspiration.
FRC (Functional Residual Capacity):
the volume of the lungs at which the outward recoil of the resting chest wall is counter-balanced by the inward recoil of the lungs. It is the volume of air that remains in the lungs after expiration of a normal breath.
RV (Residual Volume)
amount of air left in the lungs after maximal expiration.
FVC – Forced Vital Capacity
The amount of air that can be forcefully expelled, beginning with the lungs completely full. This volume is expressed in Liters
FEV1 – Forced Expiratory Volume in 1 second
Volume of air exhaled in the first second of the FVC. This volume is expressed in Liters
spirometry
most useful and basic test,
It measure the inhaled or exhaled air against time during force maneuver
instructions prior to spirometry use
- dont drink alcohol 4 hours prior to use
- dont smoke 1 hour prior to use
- dont eat heavy meal 2 hour prior
- dont wear tight clothes
- remove dentutres
- should not have MI one month
- bring medications
8- dont exercice 30 min before
problems or meds that affect result
abdominal/ chest pain, oral/ facial pain, stress incontinence , dementia, physical deformities or medical condition
meds: corticosteriod and bronchodilator
Performance of Spirometry
Attach nose clip
inhale air forecefully
put the mouthpiece in mouth and close with lips
exhale as long as fast as u can
repeat 3 times
Obstructive Disorders
Airflow is blocked or limited by airway, making it difficult to breath out
example:
asthma, emphysema, bronchitis, cystic fibrosis, bronchiectasis
Restrictive Disorders
Characterized by reduced lung volumes / decreased lung compliance (stiff or unable to expand fully)
Examples:
Interstitial Fibrosis
Cystic Fibrosis
Scoliosis
Obesity
Lung Resection
Neuromuscular diseases
Cardiovascular dis.
Trauma/chest wall dysfunction
spirometry Normal values vary and depend on:
height
gender
ethnicity
age
two types of curves
force volume curve
volume time curve
PEFR
Definition
use
results
works
definition: rate at which air expelled forcefully From lung
use: management of asthma
in acute asthmatic attack to check severity of attack
to check trends of disease progression or success
result: % of best previous value if previous not avalible predicted value
works: take 3 reading and the best one noted on peak flow chart
if reading percent less than 50% oral steriod are given
PEFR AND SEVERITY
moderate
acute sever
life threatening
moderate 50-77
acute sever 33-50
life threatening <33
Bronchodilator Testing
for diagnosis of asthma, presence of reversible airway obstruction has to be confirmed
to check change in airway following admn of bronchodilator like salbutamol nebulizer 2.5mg
positive response is 12% increase in fev1 to the base line ( pre bronchodilator)
Arterial blood gases (ABGs)
for acid base status of lungs 3 mechanism
1- buffering system: h+ ions and proton and proteins in blood
2- respiratory system: carbonic and bicarbonate buffer system,
3- renal system: excretion or retention of h+, bicarbonate and na, k, cl-
Partial Pressure Of Oxygen (PAO2, PO2)
normal value: 75-100mm hg tor
below normal value: hypoxic in anemia, emphysema
hypoventilation, pulmonary edema, embolism
increase: polycythemia, high dose of o2
Drugs which may increase PaCO2:
aldosterone, ethacrynic acid, metolazone, thiazides, hydrocortisone, prednisone, sodium bicarbonate.
Drugs which may decrease PaCO
acetazolamide, dimercaprol, methicillin, nitrofurantoin, tetracycline, triamterene.
S & S of hypercarbia / hypercapnia
acidotic state.
Headache, dizziness, and decreasing levels of consciousness.
S & S of hypocarbia / hypocapnia
alkalotic state
Tingling of fingers, muscle twitching, lightheadedness, and dizziness.
Oximetry
monitor the oxygen saturation of arterial blood.
Oximetry measures the percentage of oxygen being carried by the hemoglobin.
Normal Value: ≥95%
Oximetry performance
To perform this measurement, a light-emitting sensor is attached to a site such as the finger or wrist.
The sensor emits beams of light through the skin tissue.
A light-detecting sensor then records the amount of light absorbed by the oxygenated hemoglobin.
FEV1% Degree of severity
* mild
* moderte
* moderete severe
* severe
* very severe
- mild: >70
- moderte: 69-60
- moderete severe: 59-50
- severe: 49-35
- very severe: <35
