Last Updated on January 26, 2022 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.