Chronic Obstructive Pulmonary Disease

Last Updated on by frcemuser

  • Airflow obstruction is defined as a value of <0.7 when a ratio of the FEV1 (Forced expiratory volume in 1 second) / FVC (Forced vital capacity) is measured.

medical treatment 

  • Controlled oxygen therapy to maintain SaO2 88-92%
  • Nebulised salbutamol 2.5-5 mg
  • Nebulised Ipratropium 500 micrograms
  • Prednisolone 30 mg
  • Antibiotic agent (when indicated)

GOLD Indications for NIV include:

  • pH <7.35 and a PaCO2 >6kPa or 45mmHg
  • Severe dyspnea with clinical signs suggestive of muscle fatigue, increases work of breathing, such as use of respiratory muscles, paradoxical motion of the abdomen, or retraction of the intercostal spaces.
  • Persistent hypoxaemia, despite supplemental oxygen therapy

Setting

  • An initial Inspiratory Positive Airway Pressure (IPAP) of 10 cm H20 and Expiratory Positive Airway Pressure (EPAP) of 4-5 cm of water should be used. This should be increased rapidly at a rate of approximately 5 cm of water every 10 minutes to a target of 20 cm H2O (IPAP), or patient unable to tolerate further, or therapeutic response achieved
  • Arterial blood gas (ABG) analysis should be performed at baseline, 1 hour after commencing NIV, 4 hours after commencing NIV, and 1 hour after changing any settings

Indications for invasive mechanical ventilation:

  • A decision to intubate and proceed with mechanical ventilation should normally be made within 4 hours of starting NIV, as improvements should usually be apparent during this time
  • Patients with COPD should be considered for ITU treatment when necessary , especially if they are more unwell i.e. pH < 7.26

Prognosis 

  • One cohort study has shown that predictors of increased mortality in COPD include:
    • Increasing age
    • Significant co-morbidity
    • Decreasing post bronchodilator FEV1
    • Those patients already on long term oxygen therapy
    • Increased number of COPD exacerbations, particularly those with 3 or more episodes
    • Increased number of hospital admissions
  • A further UK audit has shown death in 14% of patients admitted to hospital within 3 months of admission. The most important prognosticators for death in this group were:
    • Poor performance status*
    • Low arterial pH on admission*
    • Presence of bilateral leg oedema*
    • Age >70
    • Home circumstances, particularly if the patient is in a nursing home
    • Unrecordable peak flow on admission
    • Pulse oximetry showing oxygen saturation under 86%
    • Intervention with assisted ventilation
      • The 3 marked with * were the 3 major independent predictors of mortality.

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