Respiratory Flashcards
What is the investigatory pathway for diagnosing asthma?
- Initial assessment: (decides probability of asthma)
-Episodic symptoms (need 2+ of the 4 symptoms for higher probability: wheeze, dyspnoea, chest tightness, cough)
-Wheeze by auscultation
-Evidence of diurnal variability
(= worse at night or early in the morning)
-PMH of atopy
-Need to check for symptoms that suggest another diagnosis
If high probability:
2. Start monitored 6 week inhaled corticosteroid trial
- Give validate symptom questionnaire or PEFR test
- Diagnosis = If there is good symptomatic and objective response to treatment response to treatment
A CLINICAL DIAGNOSIS (no one single test), since asthma is variable (test on one day might see symptoms/signs, test on another day can see nothing)
If intermediate probability:
“Only have some typical symptoms or don’t respond to treatment initiation”
- Spirometry with brondilator reversibility
- Methacholine challenge test or measure fractional expired nitric oxide FeNO (eosinophilic inflammation)
If low probability:
- Investigate for alternative diagnosis
What are vesicular breath sounds? What are they like? (Pitch, loudness, durations, gaps)
Normal breath sounds.
No gap between inspiration and expiration
Inspiration is longer than expiration
Soft
Low pitch
What are bronchial breath sounds?
What are they like? (Pitch, loudness, durations, gaps)
Could be described as a wheeze by patient, but it is distinct from wheeze.
Abnormal breath sound caused by smaller airways.
Loud
High pitch
Gap between inspiration and expiration
Inspiration is same duration as expiration
What is a wheeze? How does it sound? (Pitch, loudness, duration, gaps)
A musical sound caused by narrowing of the airways (bronchospasm, scarring, secretions etc)
Can be Low or high pitch
Low = sonorous, due to secretions
High = sibilant, due to bronchospasm (asthma)
Can be Polyphonic or monophonic
Polyphonic = asthma wheeze (widespread bronchospasm degree is variable, many different wheezes together)
Monophonic = localised obstruction (means only one area generates the wheeze, so one tone)
What is respiratory crackle? (AKA crepitation)
An inspiratory (ONLY) rumble.
Not heard on expiration.
Can be early/middle/late/biphasic in the inspiratory phase.
Can be fine or coarse quality.
Caused by: interstitial fibrosis or fluid secretions, as air comes in to the lung the airways pop open, causing the crackling sound.
What is a pleural rub? (Inspiratory or expiratory)
Sound caused by pleural inflammation, causing the visceral and parietal pleura to rub on oneanother during inspiration
Inspiratory
Low pitch
Grating sound
What is the objective definition of a moderate acute asthma attack?
PEFR is 50-75% of best (or predicted)
Signs:
RR is >20
HR is >90
What is the objective definition of a severe acute asthma attack? (PEFR)
PEFR is 33-50% of best (or predicted) and respiratory rate is >25/minute
Signs:
RR is >25
HR >110
Speaking in incomplete sentences
What is the objective definition of a life-threatening acute asthma attack?
PEFR <33%
SpO2 <92%
Subjective criteria: altered consciousness exhaustion cardiac arrhythmia hypotension cyanosis poor respiratory effort silent chest confusion
Which three questions must be asked in a yearly asthma review?
(We’re trying to establish wether the current management is adequate for the patient)
- In the past year has your asthma caused any difficulty sleeping?
- Have you had your usual asthma symptoms during the day?
- Has your asthma interfered with your usual daily activities?
We must also record PEFR
What is an A-a gradient?
The difference in oxygen concentration between the alveoli (A; approx atmospheric) and in the arteries (a)
= PAO2-PaO2
Remember that alveolar is always higher conc than arterial.
If the gradient is too high it indicates a lung issue.
What is the peak expiratory flow rate?
The maximal rate that a person can exhale during a short maximal expiratory effort after a full inspiration.
What is the main benefit of ABGs over VBGs?
ABGs give representative oxygen and carbon dioxide levels.
By the time blood is in the venous system the gas profile has changed a lot.
However VBGs are just as good as ABGs for pH and Bucarbonate levels.
What are light’s criteria for pleural effusion samples?
Light’s criteria differentiates transudate from exudate.
Depends on relative protein and lactate dehydrogenase concentration (released during cell damage): both should be low in the pleural fluid.
If any of the following are met, the sample is an exudate:
- Pleural/Serum protein >0.5
- Pleural/Serum Lactate dehydrogenase >0.6 (LDH)
- Pleural LDH is >2\3 upper limit of normal serum LDH
Which conditions cause extremely high (>4g/L) pleural fluid protein content?
TB
Multiple myeloma
Waldenstroms macroglobulinaemia
