Respiratory Flashcards
SMART-COP criteria
- Systolic BP (less than 90 mmHg) - 2 pt
- Multilobar CXR involvement - 1 pt
- Albumin (less than 35 g/L) - 1 pt
- Respiratory rate (≥30) - 1 pt
- Tachycardia (≥125) - 1 pt
- Confusion - 1 pt
- Oxygenation (PaO2 ≤59 mmHg, SaO2 ≤90%, PaO2/FiO2 ≤249) - 1 pt
- pH arterial (less than 7.35) - 2 pt
Severe CAP = score ≥5
CURB65 score
- Confusion, AMT ≤8
- Urea >7mmol/L
- Respiratory rate ≥30/min
- Blood pressure less than 90/60 mmHg
- Age 65 or more
Severe CAP = score ≥3
Long term O2 therapy indications
PaO2 ≤55 mmHg or SaO2 ≤88% OR PaO2 ≤59 mmHg or SaO2 ≤89%, with: - ECG evidence of P pulmonale - Hematocrit >55 percent - Clinical evidence of right heart failure
Hb-oxygen dissociation curve left shift
Carbon monoxide
Foetal haemoglobin
Decrease in: Temperature Acidity 2,3-DPG pCO2
Hb-oxygen dissociation curve right shift
Increase in: Temperature Acidity 2,3-DPG pCO2
Alveolar-arterial gradient (A-a gradient) calculation
=FiO2(Patm - PH2O) - PaCO2/0.8 - PaO2
=0.21 (760 - 47) - 1.25(PaCO2) - PaO2
Normal A-a gradient
Less than 15mmHg:
- Hypoventilation (high PaCO2) - CNS depression, neuromuscular disease, kyphoscoliosis, obesity hypoventilation
- Low PiO2 (low PaCO2) - altitude, aircraft cabin
Widened A-a gradient
Equal or greater than 15mmHg:
- Diffusion defect (normal PaCO2) - ILD, elite athlete during exercise
- V/Q mismatch (normal PaCO2, overcome by high flow O2) - pneumonia, APO, ARDS, atelectasis, ILD
- Right-left shunt (normal/low PaCO2, true shunt not overcome by high flow O2) - PFO, ASD, pulmonary AVM
- Increased O2 extraction
Blood gas - Methaemoglobinaemia
- Chocolate brown blood
- Normal PaO2
- SaO2 usually 85-90%
- Saturation gap (Oximetry SaO2 5% lower than ABG SpO2)
Blood gas - Carboxyhaemoglobinaemia
- Cherry red skin and lips
- Normal PaO2
- Decreased ABG SpO2
- Normal oximetry SaO2
Methacholine provacation test
Specific for asthma diagnosis.
Reduction in FEV1 of 15% or more, using 4mg/ml or less.
Bronchodilator reversibility
Increase in FEV1 by at least 12% and 200ml.
Best predictor of mortality in COPD
Acute exacerbation with hospital admission
Spirometry - asthma
FEV1 ≤80% FER ≤70% DLCO ≥75% (normal or high) TLC ≥80% Bronchodilator response - more than 12% and 200ml
Major form of carbon dioxide in the blood
Bicarbonate ion - 80%
Carbamino compound bound to Hb - 10%
Dissolved in plasma - 10%
(Diffuses to RBC then rapidly anhydrated by intracellular carbonic anhydrase to carbonic acid, then dissociates to bicarbonate)
Obstructive sleep apnoea - cardiac physiology
Increased LV afterload Decreased LV preload Increased RV venous return Increased sympathetic outflow Decreased stroke volume (during apnoea) - increased with relief from obstruction
Obstructive sleep apnoea - definition
Polysomnography with more than 5 obstructive events per hour with symptoms/comorbidities, or more than 15 obstructive events per hour regardless
Central sleep apnoea - definition
Polysomnography with more than 5 central events per hour with symptoms/comorbidities, and no Cheyne-Stokes breathing
Obesity hypoventilation syndrome - definition
Obesity - BMI more than 30
Alveolar hypoventilation - PaCO2 more than 45mmHg (while awake, with no other cause)
Nocturnal hypoventilation - increase in PaCO2 more than 55mmHg or rise of 10mmHg exceeding 50mmHg for 10 min or more
Narcolepsy - definition
EDS - more than 3 months
Mean sleep latency - 8 minutes or less
SOREM - 2 or more naps with sleep onset to REM within 15 minutes
Type 1 - CSF hypocretin-1 less than 110 picograms/ml, cataplexy present
Type 2 - normal CSF hypocretin-1, cataplexy absent
Chronic obstructive pulmonary disease (COPD) - criteria for long-term azithromycin prophylaxis
COPD with 2 or more exacerbations per year
HR less than 100, QTc less than 450
Sputum culture mycobacterium negative
No baseline high cardiac risk
Idiopathic pulmonary fibrosis (IPF) - treatment
aka usual interstitial pneumonia (UIP)
Anti-fibrolytic - pirfenidone or nintedanib
Triple therapy - N-acetyl cysteine, prednisolone, azathioprine
Well’s score for pulmonary embolism (PE)
Clinical symptoms of DVT (3) No alternative diagnosis (3) Previous DVT/PE (1.5) Immobilisation/surgery past month (1.5) Tachycardia more than 100 (1.5) Malignancy (1) Haemoptysis (1)
PE likely = score more than 4
Spirometry - obstructive defect
FEV1/FRC (ie. FER) ≤70% or LLN
Spirometry - restrictive defect
TLC less than 80% or LLN, with normal FER
Alpha-1 antitrypsin deficiency (AAT) - lung pathophysiology
Toxic loss of function - AAT normally inhibits elastase, results in proteolytic degradation of elastin
Lung transplant - contraindications
Uncontrolled infection Malignancy last 2 years Significant dysfunction in other organs Significant coronary artery disease or HF Chest wall / spine deformity Active smoking Drug / alcohol dependency HIV infection / active hep B or C infection Obese BMI ≥35
