What co-morbidities contribute to shortness of breath?
- Pneumothorax
- Cardiac problems/ heart disease/ heart failure
- pulmonary hypertension caused by embolism
- anaemia
- pneumonia
- anxiety
- lung cancer
- COPD
What can cause an acute exacerbation of COPD?
- respiratory infection
- exposure to smoke/ pollution
What are symptoms of infective exacerbations?
- coughing up yellow/green sputum
- lack of appetite
- swelling in both ankles
- pyrexia
- low O2 sats
- difficulty breathing
What tests are used to diagnose the cause of exacerbations?
- Chest X-ray
- Blood/ arterial blood gas tests (to test Hb, pH, pCO2, pO2)
- ECG
- Sputum test
What is acidosis and what are the 2 types?
Acidosis is a disorder that leads to acidaemia (when pH <7.35) .
- Respiratory acidosis
- Metabolic acidosis
How can the 2 types of acidosis be differentiated?
- Respiratory acidosis: ⬆️ CO2 –> ⬆️ HCO3- —-> ⬇️ pH (more acidic)
- Metabolic acidosis: Too much acid which consumes HCO3- (⬇️ in bicarbonate) –> ⬇️ pH (not related to CO2 but more to do with the inability of the intercalated cells in the kidney collecting ducts to maintain acid/base balance)
What are the 2 types of respiratory acidosis/failure?
- Type 1 Respiratory failure
- Type 2 Respiratory failure
What is the mechanism behind Type 1 respiratory failure?
Failure of the heart/lungs to provide adequate O2 to meet metabolic demands (hypoxemia). The CO2 is usually normal/low.
What are some causes of Type 1 RF?
- R-L cardiac shunt (allows blood from R/L sides to mix)
- Alveolar hypoventilation
- Pulmonary embolism
- Asthma
- Pneumothorax
- Lung collapse
- Acute Respiratory Distress Syndrome
What is the mechanism behind Type 2 RF?
The failure of the lungs to remove CO2 (hypercapnia). O2 levels will also be affected.
What are some causes of Type 2 RF?
- drug overdose
- head injury
- upper airway obstruction (oedema, infection)
- COPD
What test is used to evaluate Metabolic acidosis?
Anion gap:
(Na+) -(HCO3-)- (Cl-)= Anion gap (8-16mmol/l)
(Na+) +(K+) -(HCO3-)- (Cl-)= Anion gap (12-20mmol/l)
What does a high anion gap suggest?
(>30mmol/l) Metabolic acidosis
- High anions (bicarbonate)
What can cause a high anion gap?
- Lactic acidosis
- Ketoacidosis
- Renal failure
What causes normal anion gap metabolic acidosis?
- The bicarbonate ions are replaced by excess Cl-
- Can be caused by diarrhoea + renal tubular acidosis
What is alkalosis and what are the 2 types?
Alkalosis is a disorder that leads to alkaemia (when pH >7.45) .
- Metabolic
- Respiratory
What happens in metabolic alkalosis? What can cause it?
⬆️ Bicarbonate ions -> ⬆️ pH
Caused by…
- excess antacid consumption
- kidney diseases
What happens in respiratory alkalosis? What can cause it?
⬇️ CO2 -> ⬇️ Bicarbonate ions -> ⬆️ pH
Caused by…
- hyperventilation
- high altitude
What is the compensatory mechanism for respiratory acidosis?
Metabolic alkalosis:
1) More CO2 + H20 -> HCO3- + H+ by carbonic anhydrase
2) Kidney excretes H+ and retains HCO3-.
3) ⬆️ pH
What is the compensatory mechanism for metabolic acidosis?
Respiratory alkalosis:
1) More ventilation to ⬇️ CO2
2) ⬇️ Carbonic acid, ⬇️ H+
3) ⬆️ pH
What can be seen on a Chest X ray, in an infective exacerbation of COPD?
Opacification of parts of the lung (area of whiteness) -> air in alveoli have been replaced by bacteria
How would the chest X-ray be different for a pleural effusion?
In a pleural effusion, fluid builds up between the pleura of the lungs.
There will be opacification but it will be more contained in a certain area.
With infections, the whiteness will generally be more spread out.
What is the initial drug management of an infective exacerbation of COPD?
- Bronchodilators (SABA/LAMA inhalers with nebulisers)
- Corticosteroids (to help relieve breathlessness)
- Broad-spectrum antibiotics
- Oxygen therapy
(mucolytics -> carbocisteine, antivirals)
What are the initial non-drug management options for an infective exacerbation of COPD/ Type 2 RF?
- BiPAP
- Encouraging them to sit upright
- Chest physiotherapy
