Respiratory Flashcards
(198 cards)
define asthma ?
- chronic inflammatory airway disease leading to variable airway obstruction
- bronchoconstriction is reversible with bronchodilators
name 3 respiratory emergencies
anaphylaxis
pneumothorax
pulmonary embolism
define ventilation
movement of air into and out of lungs during a single breathing cycle
what is alveolar ventilation and how do you calculate it?
total volume of air that reaches the alveoli and contributes to gas exchange
alveolar ventilation = RR x (tidal volume - dead space volume)
why is the concept of physiological dead space important?
physiological dead space = volume of lung that doesn’t eliminate CO2
- important because if this space increases (e.g. pneumonia) then patient needs to increase minute ventilation to maintain adequate gas exchange
what is hypoxic pulmonary vasoconstriction?
physiological response to alveolar hypoxia
- if PA02 decreases, pulmonary arterioles vasoconstrict to limit blood flow to hypoxic alveoli
what is the V/Q ration if ventilation is 4L/min and perfusion is 5L/min ?
4/5 or 0.8
what happens to V/Q ration if you decrease ventilation or perfusion?
decreased ventilation? V/Q ration decreases
increased ventilation? V/Q ratio increases
NB both V&Q are greater at the lung bases than apices
spirometry: what is FEV1?
Forced expiratory volume in 1 second (FEV1) = air a person can forcefully exhale in 1 second.
Measures how easily air can flow out of the lungs.
Reduced with airflow obstruction.
spirometry: what is FVC?
forced vital capacity = total air a person can exhale after a full inhalation
Measures volume of air someone can take into their lungs
Reduced with restricted lung capacity
when can we diagnose obstructive lung disease on spirometry?
Diagnosed when the FEV1 is less than 70% of the FVC = FEV1:FVC ratio of less than 70%
someone may have good lung volume but air can only move slowly in or out of lungs
causes of obstructive lung disease?
- asthma
- COPD
- bronchiectasis
- A1AT
- CF
when can we diagnose restrictive lung disease on spirometry?
- FEV1 and FVC are equally reduced
- FEV1:FVC ratio greater than 70%
lungs have limited ability to expand and fill with air
causes of restrictive lung disease?
fibrosis
sarcoidosis
obesity
MND
asthma risk factors?
- atopy (or FHx of atopy)
name 5 common asthma triggers?
Infection
Nighttime or early morning
Exercise
Animals
Cold, damp or dusty air
Strong emotions
name two medication classes that can worsen asthma symptoms?
- Beta-blockers, particularly non-selective beta-blockers (e.g., propranolol)
- NSAIDs (e.g., ibuprofen or naproxen)
what type o wheeze do you hear in asthma?
widespread “polyphonic” expiratory wheeze
asthma Px?
- episodic sx
- diurnal variation - worse at night
- SOB
- chest tightness
- dry cough
- wheeze - widespread, polyphonic
- reduced PEFR
asthma Ix?
NICE recommend:
1. Fractional exhaled nitric oxide (FeNO)
2. Spirometry with bronchodilator reversibility
Others to add in:
3. peak flow diary
4. direct bronchial challenge - opposite of reversibility testing
what % increase of FEV1 on reversibility testing suggests asthma?
greater than 12% increase in FEV1
BTS asthma management?
- SABA - salbutamol
- Add ICS - low dose beclometasone
- Add LABA - salmeterol / maintenance and reliever therapy (MART)
- Increase ICS dose / add leukotriene receptor antagonist (LTRA) - montelukast
- Specialist mx - eg oral prednisolone
NICE asthma management?
- SABA - salbutamol
- Add ICS - low dose beclometasone
- Add LTRA - montelukast
- Add LABA - salmeterol
- Consider changing to MART
- Increase ICS dose
- Consider high dose ICS or additional drugs - LAMA / theophylline
- Specialist mx - eg oral prednisolone
what other things are involved with asthma management other than asthma medication?
- ?occupational - refer to resp
- yearly flu jab
- yearly asthma review
- consider stepping down tx every 3mo or so
- reducing ICS dose - only by 25-30% at a time
- regular exercise, avoid smoking, avoid triggers