Tuesday, 13 January 2015

Exacerbation of COPD

Definition of Exacerbation
You'd have thought that defining an exacerbation would be easy...but everywhere seems to have different exacerbation:
- worsening of the patient's symptoms from stable state that is beyond normal day-to-day variations, and is acute in onset.
- Anthonisen criteria - increased dyspnea, increased sputum volume, and increased sputum purulence 

Investigations
- CXR in all patients coming into hospital 
- ABGs
- ECG
- FBC, U+E

Antibiotics?
- Purulent sputum is often used, but limited accuracy. 
- Bloods - markers of infection are hypothetically useful. 
- GP notebook advises antibiotics if increased in purulent sputum or suspected pneumonia. 

Medical Management
Maximum medical treatment includes:
Controlled oxygen therapy to maintain SaO2 88-92%
Nebulised salbutamol 2.5-5 mg
Nebulised Ipratropium 500 micrograms
Prednisolone 30 mg for 7 to 14 days
Antibiotic agent when indicated
Conflicting evidence about the role of IV magnesium

NIV
NIV should be considered within 60 minutes of arrival to hospital in all patients with an exacerbation of COPD and a persistent respiratory acidosis (pH <7.35 and PaCO2 >6 kPa) in whom medical treatment unsuccessful. 
Patients should improve within four hours - if they don't, consider intubation. 

Exclusion criteria
Life-threatening hypoxaemia
Severe co-morbidity
Confusion/agitation/severe cognitive impairment
Facial burns/trauma/recent facial or upper airway surgery, vomiting, upper airway obstuction, secretions, inability to protect the airway
Haemodynamically unstable requiring
inotropes/pressors (unless in a critical care unit)
Patient moribund
Bowel obstruction
May be used in heart failure or pneumonia

NIV Technique
- Full face mask for 24hours
- Start with an IPAP of 10cm H20, EPAP of 4-5cmH20
- IPAP should be increased by 2–5 cm increments at a rate of approximately 5 cm H2O every 10 minutes
- Bronchodilators, although preferably administered off NIV, should as necessary be entrained between the expiration port and face mask. 

Repeat ABGs:
– after 1 hour of NIV therapy and 1 hour after every subsequent change in settings
– after 4 hours, or earlier in patients who are not improving clinically

Invasive Intubation 
NIV failure or inability to tolerate NIV
Respiratory or cardiac arrest
Respiratory pauses with loss of consciousness or gasping for air
Reduced consciousness or uncontrolled agitation
Massive aspiration
Persistent inability to remove respiratory secretions
Heart rate < 50 with loss of alertness
Haemodynamic instability unresponsive to fluid and vasopressors
Life threatening hypoxaemia

Home or Hospital?

Mortality 
DECAF score

- If intubated and ventilated have an in- hospital mortality of 25%. Two thirds will be dead within a year.  Patients do better than people think. 


References

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