Chronic Obstructive Pulmonary Disease

OVERVIEW

  • COPD = chronic bronchitis +/- emphysema
  • aka CORD (respiratory) or COAD (airways)
  • environmental factors: tobacco smoke and air pollution
  • host factors: balance between circulating proteases and antiproteases (alpha-1-anti-trypsin deficiency), anti-oxidants (vitamins A, C and E)

HISTORY

  • COPD exacerbation symptoms – SOB, wheeze, sputum
  • smoking
  • exercise tolerance
  • ADL’s
  • home O2
  • home CPAP/NIV
  • respiratory medications + compliance
  • steroid use
  • heart failure medications
  • frequency of hospitalisation
  • mechanical ventilation

PRECIPITANTS OF AN EXACERBATION

  • infective (bacteria = Pneumococcus, H. influenzae, Strep viridans, Moraxella catarrhalis, Mycoplasma pneumoniae, Pseudomonas, viruses = rhinovirus, influenza, parainfluenza, corona viruses, adenovirus, RSV)
  • aspiration
  • LVF
  • sputum retention
  • PE
  • pneumothorax
  • uncontrolled O2
  • sedation
  • non-compliance with medications
  • nutritional (K, PO4, Mg deficiency, CHO excess)
  • sleep apnoea

EXAMINATION

  • steroid skin
  • cachexia
  • nutritional assessment
  • plethora
  • chest signs of severity: hyperinflation, accessory muscle use, cyanosis

INVESTIGATIONS

  • previous ABGs: hypoxia, hypercapnia, metabolic compensation
  • CXR: hyperinflated, flattened diaphragms, paucity of lung markings, PHT -> enlarged proximal lung markings
  • electrolytes: especially tCO2 -> bicarbonate compensation in chronic hypercapnoea
  • previous spirometry: FEV1/FVC – degree of emphysema, hyperexpanson, evidence of right and left heart failure
  • formal pulmonary function tests: DLCO, flow-volume loops – concaved expiratory flow pattern
  • ECG: right heart strain, RV hyperthrophy, P pulmonale, RAD, RBBB, ST depression or inversion in V1-V3
  • Hb: polycythaemia
  • high resolution CT: characteristic changes

Spirometry

  • MILD = FEV1 50-60% predicted
  • MODERATE = FEV1 30-50% predicted
  • SEVERE = FEV1 <30% predicted

MANAGEMENT

  • Uncontrolled O2 – may cause hypercapnic respiratory failure due to:
    (1) shunting of blood to low V/Q units -> increasing dead space
    (2) loss of hypoxic drive
    (3) dissociation of CO2 from Hb (Haldane effect)
    (4) anxiolysis and reduction in tachypnoea

Bronchodilators

  • there is often a reversible component and also improves mucocillary clearance
  • nebulised beta-agonists + aminophylline

Anti-cholinergics

  • ipratropium bromide 500mcg NEB Q6hrly
  • tiotropium (Spiriva) one PO OD

Steroids

  • improves airflow obstruction in those requiring mechanical ventilation
  • avoid when exacerbation clearly due to pneumonia without bronchospasm

Antibiotics

  • accepted role when exacerbation secondary to infection

Secretion clearance

  • chest physio
  • nebulised mucolytic agents
  • oropharyngeal/nasopharyngeal suctioning
  • bronchoscopy

NIV

  • those with hypercapnic respiratory failure
    -> improved physiology
    -> reduced need for mechanical ventilation
    -> reduced length of stay

Mechanical Ventilation (if indicated)

  • IPPV: avoid dynamic hyperinflation and barotrauma

-> low RR
-> low I:E (1:4)
-> support spontaneous breathing preferred to fully ventilated IPPV
-> titrated support to avoid respiratory muscle fatigue but avoid atrophy
-> aim for early extubation -> NIV
-> aim for PaO2 55mmHg
-> aim for normal PaCO2 (may have to allow permissive hypercapnoea)
-> measure DHI
-> measure PEEPi
-> discontinue futile therapies if not appropriate

CCC Ventilation Series

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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