COPD Flashcards
what is a pack year
number of packs x number of years smoked
20 cigs = 1 pack
what is COPD?
airflow obstruction with little to no reversibility
includes chronic bronchitis and emphysema
what is chronic bronchitis
cough and sputum production on most days for 3 months, of 2 successive years
what is emphysema
enlarged air spaces distal to terminal bronchioles; destruction of alveolar walls
may join together to form a bullae that ruptures and causes a pneumothorax
difference between COPD and asthma
both obstructive diseases but asthma is reversible
what are the causes of COPD
genetics:
- alpha-1-anti-trypisin deficiency (Still need to smoke) = A1AT protects against tissue damage from neurtrophil elastase which is induced by smoking
other gene polymorphisms eg those against metaloproteinases that protect lung against inflammation
active and passive smoking, cannabis, biomass fuels
what are the 3 pathological changes to the lungs and the main features of COPD
goblet cell hyperplasia, causing cough and sputum
airway narrowing causes breathlessness and wheeze
alveolar destruction
main features: bronchoconstriction, musocal oedema and mucosal hypersecretion
pathogenesis of COPD?
epithelial cells allows entry of cig smoke
macrophages and dendritic cells = activation of IS
proteases cause mucus production
damage lungs
fibroblasts scar airways
why do you get type 2 resp failure in COPD?
- loss of elastic recoil
- gas trapping and reduce excretion of CO2
- forms carbonic acid in blood
- progressive CO2 retention = compensation by kidneys reabsorbing more bicarbonate to neutralise it
-but CO2 will always be high and SOB = low oxygen levels
what are the symptoms of COPD?
smoker or ex-smoker >35
exertional breathlessness chronic cough regular sputum production winter exacerbations wheeze
what are the physical signs of COPD
tar staining central cyanosis tachypnea chest hyperexpansion = BARREL SHAPED cor pulmonale wheeze palpable liver edge use of acessory muscle on inspiration
how do you stage COPD
GOLD stages, based on FEV1 ratio
1>80%
2 50-79%
3 30-49%
4<30%
what is the BODE index?
predicts survival in COPD patients, based on FEV1% of predicted, 6 minute walk distance, BMI, and mMRC dyspnea scale
what are the investigations you do for COPD?
spirometry
ABGS
CXR
CT
how are ABGS used in COPD
- always check pH first
- may find both types of resp failure
- after that, check compensation:
- compensated if HCO3 is abnormal; if raised = degree of chronicity but if pH is low it has not compensated
BE = metabolic component? if infection, BE is low
what is type 1 resp failure
- low oxygen
- hypoxaemic failure, <8kPa
- underlying pathology with LUNGS eg infection, oedema or shunt
what is type 2 resp failure and what are the clinical features?
low oxygen and high co2
-may lead to low pH and high CO3
-dilated pupils, bounding pulse, hand flap, myoclonus, confusion and drowsiness
what would you see on a CXR of COPD
often normal but exclude other conditions
low, flattened diaphragms nipple shadows smaller heart size horizontal ribs hyper-expansion
what would you see on a CT scan of COPD
holes or bullae suggesting emphysema (in apices)
bronchial wall thickening
how is COPD used in spirometry
measures VC and FVC (refer to asthma flashcards)
how do you differentiate between asthma and COPD?
using spirometry
- asthma will have:
- a large response >400ml to bronchodilators or 30mg oral prednisolone daily for 2 weeks
- serial peak flow measurements showing >20% diurnal variability
- night time waking with breathlessness or wheeze
what happens if a COPD patient stops smoking?
lung function stops declining as quickly but not reversible so symptoms will still prevent but just later in life
what is cor pulmonale and why do you get it
it is right sided heart failure as a result of chronic hypoxic lung disease
- hypoxia
- pulmonary arterial vasoconstriction
- increased pulmonary artery pressure
- RV hypertrophy
- RV failure
how do you treat COPD?
-STOP SMOKING
- start SABA
- if still breathless, add LABA or anti-muscarinic in preference to SAMA (LAMA)
- if FEV1 ratio <50% or frequent exacerbations add inhaled CCS in combined inhaler with LABA
- if still breathless consider pulmonary rehab, theophylline or high dose bronchodilators
what other non-pharmacological treatments can you give to COPD patients
- flu and pneumococcal vaccine
- oxygen short burst for symptoms if >15 hours a day
- physio for breathing
may need bullectomy, lung volume reduction surgery or lung transplantation
what are the complications of COPD
exacerbations pneumonia pneumothorax RVF peripheral neuropathy cachexia
what causes a COPD exacerbation
viruses and bacteria such as H.influenzae, S.pnemonia, pseudomonas
what are the symptoms of a COPD exacerbation
preceding coryzal symptoms increased breathlessness increased cough increased sputum sputum purulence ankle swelling
wha investigations would you do in a COPD exacerbation
CXR ABG or o2 sats ECGs FBC, U&Es, CRP sputum culture
how do you manage a COPD exacerbation
- oxygen, SaO2 not more than 94% in selected cases if hypercapnic
- high dose SABA, nebulised
- high dose CCS (prednisolone 40mg/day - 7 days) to reduce inflammation
- antibiotic ONLY if purulent sputum
reassess after an hour
what do you do if, after an hour, a COPD exacerbation patient is still in resp acidosis?
- IV bronchodilator: salbutamol or theophylline
- ICU
- non invasive ventilation
- then intubation or assisted ventilation
what are the 3 ways of oxygen delivery devices
nasal cannulae: 60% delivery, max oxygen 5L oxygen/minute
non-rebreathing mask - control of acute patients, 15L/min = 85% of FiO2
- cannot regulate amount of inspired oxygen but once initial assessment is complete, reduce oxygen to appropriate target sats of 94-98%
venturi mask - exact control of FiO2, and avoids over-oxygenation
