Clinical Scenario

• Mr X - Pt 1:

  • 68 yr old man admitted with an exacerbation of COPD
  • 45 pack year history - 20 cigarettes a day for 45 years
  • Respiratory rate 36 – normal is 12 - 15/16, above 30 is concerning
  • Ausc: decreased amount of breath sounds throughout, no added sounds
  • Fixed upper limbs - sign of respiratory distress
  • Using accessory muscles - sign of respiratory distress
• Mr X - Pt 2:

  • No cough
  • CXR – hyperinflated, Right upper lobe bulla
  • Barrel chest
  • Central cyanosis – a blue colour to your lips, maybe also tip of nose - indicates hypoxemia
  • Cachectic - very thin/malnourished
• Mr X therefore has emphysema
• Mr X - Pt 3:

  • ABGs on 24% O2
  • pH 7.31↓
  • PaO2 7↓
  • PaCO2 11↑
  • HCO3 32↑
  • BE +4 ↑
  • therefore this is a respiratory acidosis, with partial compensation and hypoxia
  • this is a type 2 respiratory failure - low o2, high co2
• Mr X - Pt 4:

  • The team decide to increase Mr X’s O2 to 28%
  • ABG after 1 hour on 28% O2
  • pH 7.30
  • PaO2 10
  • PaCO2 13
  • HCO3 32
  • BE + 4
• Mr X - Pt 5 - Why has the CO2 risen and pH dropped? reason 1:

  • more O2 leads to reversal/loss of HPVC -> blood goes through poorly ventilated areas of lung -> worsening V/Q mismatch
• Mr X - Pt 5 - Why has the CO2 risen and pH dropped? reason 2:

  • Haldane effect - rbc in hypoxemic pts also carry co2 as theres not enough o2 to carry, hb prefer combining with o2, so if pt given more o2, hb will dump co2 into plasma to pick up o2
• Mr X - Pt 5 - Why has the CO2 risen and pH dropped? reason 3:

  • Loss of hypoxic drive - central chemoreceptors are desensitised in COPD, so pt with COPD are reliant on peripheral chemoreceptors, which are sensitive to hypoxia, so too much o2, the peripheral chemoreceptors wont detect low o2 -> decreases drive to breathe -> decreases ventilation -> increases co2
• What should we do to improve the ABGs?

  • Non-Invasive ventilation:
  • ventilating pts via face masks
  • provides adequate amount of o2 to keep pao2 above 8 kpa
  • also increases ventilation/tidal volume to make sure co2 is cleared adequately
• Mr X - Physiotherapy Management:

  • Positioning to ease shortness of breath
  • Breathing control at rest
  • Refer to dietician
  • Mobilise on O2 with breathing control on exertion
  • Advise to stop smoking and refer to smoking cessation programme
  • Stairs prior to discharge
  • Refer to pulmonary rehab programme prior to discharge