COPD and Oxygen for Dentists

• Chronic bronchitis:

  • Chronic or recurrent excessive mucous secretion in the bronchial tree
  • If a person coughs up phlegm for most days in a three month period in two consecutive years, then that meets the diagnostic criteria for chronic bronchitis
• Emphysema:

  • An increase beyond the normal in the size of the air spaces distal to the terminal bronchiole accompanied by destruction of their walls & without obvious fibrosis
  • Gas exchange in the lungs takes place in the alveoli, this is where you absorb oxygen and get rid of carbon dioxide
  • Emphysema, when the air sacs are damaged in the alveoli, gas exchange is affected - oxygen levels are lower than they should be because not as much is able to be absorbed because the surface area for gas exchange is smaller

  
• Smoking is the main cause of emphysema, along with exposure to coal dust and other occupational exposures.

  
• Chronic bronchitis and emphysema fall under the umbrella of COPD. Airway obstruction and spirometry are part of the diagnostic criteria for COPD.
• As you blow into the machine's tube, the graph paper moves along and can record the volume of air in your lungs.

  
• FVC = forced vital capacity = how much they can breathe out in full - in this example is 5 litres

  
• FEV1 = forced expiratory volume in 1 second = how much they can breath out in 1 second - in this example is 4 litres

  
• FEV1 divided by FVC gives us the ratio - in this example it's 80%

  
• This graph is one for someone with airflow obstruction - can tell because ratio is only 60% and FEV1 is 3 litres

  
• Working definition of COPD:

  • Airflow obstruction is defined as an FEV1/FVC ratio of < 0.7 (70%)
  • There also needs to be some kind of airway and parenchymal (lung tissue) damage
  • Chronic inflammation due to smoking (not asthma) should be present too
  • Characteristic symptoms (though patient may not complain of any symptoms) - the symptoms the patient would have would be: breathlessness, cough and phlegm production
• Stopping smoking is the only thing that really stops COPD worsening with time (due to loss of lung function over time).
• Shortness of breath is one of the main symptoms people with COPD have.
• Frequent exacerbations:

  • Exacerbation is when you get a worsening of symptoms - the symptoms in this case being: cough, shortness of breath, and phlegm
  • Fot pts who already produce phlegm on a daily basis, the exacerbation could be an increase in the amount, a change in the thickness or a change in the colour
  • A course of steroids or oral antibiotics could be taken to treat exacerbation episodes
• Respiratory failure is when a pt's oxygen levels are low.
• Cor pulmonale is when a pt's oxygen levels are extremely low and pressure is put on the right side of the heart.
• Abnormally low BMI can happen in patients with COPD in more advanced stages.
• Anxiety and depression are very common in patients with COPD; they're often breathless on a day-to-day basis, can make them feel panicky.
• FEV1% predicted with time:

  • The FEV1% predicted is a calculation of a pt's expected value
  • This graph looks at the change in lung function as people get older
  • Can calculate a pt's lung function based on their age, sex and height
  • Men, on average, have a higher lung capacity - taller people have bigger lungs
  • As you age, lung function decreases

  
• FEV1% predicted with time:

  • Stopping smoking slows the decline of FEV1, but doesn't stop it altogether
  • Very important
  • If you stop smoking, whilst your lungs may get worse with time, it's far better than continuing to smoke
  • Death line = patients with COPD will die from COPD - 1 in 3 smokers will die as a direct consequence of smoking/smoking related disease (COPD is one of the common ones)
• Treatments for COPD:

  • Smoking cessation
  • Vaccinations
  • Pulmonary rehabilitation
  • Inhaled therapy - LABA/LAMA/ICS
  • Anti-inflammatory/antibiotic therapy
  • Medication to help cough up phlegm - such as carbocisteine
  • In select pts, long-term oxygen therapy
  • Treatments for other health problems
• Treatments for COPD - smoking cessation = most effective treatment
• Treatments for COPD - vaccinations:

  • Ensure they get them on a yearly basis
  • Effectiveness of flu vaccine varies from year to year, but guaranteed 30-70% protection from flu if you get the vaccine
  • Pts with COPD will suffer with coronavirus more if they get it
• Treatments for COPD - pulmonary rehabilitation:

  • One of the best treatments to improve breathlessness
  • Pts go and do exercise courses (6-12 weeks) - undergo supervised exercise targeted to them (since some pts will be quite limited in what they can do) - supervised by a respiratory physiotherapist
• Treatments for COPD - inhaled therapy (LABA/LAMA/ICS):

  • LABA = long-acting beta agonist - opens up the airway (bronchodilator)
  • LAMA = long-acting muscarinic antagonist - opens up the airway
  • ICS = inhaled corticosteroid - reduces inflammation
  • These treatments improve breathlessness and QoL and reduce exacerbation frequency
  • All 3 types can be provided in 1 inhaler now
• Treatments for COPD - anti-inflammatory/antibiotic therapy:

  • May be placed on a drug like azithromycin if the pt is getting frequent infections
  • Normally taken on a Monday, Wednesday, and Friday
  • An antibiotic and an anti-inflammatory - its purpose is to try to reduce exacerbation frequency
  • Azithromycin can expose the pt to heart arrhythmia - but the chances of that happening are very low
• Treatments for COPD - medications to help cough up phlegm (such as carbocisteine):

  • Can be taken 3 times a day
  • It thins the phlegm so that it's easier to cough up
  • For pts with a lot of phlegm secretions in their chest, you want them to clear it; if those secretions are in the lungs then they can predispose to further infections and inflammation
• Treatments for COPD - in select pts, long-term oxygen therapy:

  • This is indicated in pts who have very low levels of oxygen in their blood
• Treatments for COPD - treatments for other health problems:

  • eg smoking is a main risk factor for COPD, but is also a risk factor for heart disease and other problems
  • Pts with COPD are more likely to have diabetes and heart failure - but these are likely to be missed; symptoms will be put down to their COPD
• Definition of respiratory failure:

  • PaO2 (partial pressure of oxygen) < 8 kPa (kilopascals)
  • Can be found by taking a blood sample from a patient's artery and measuring the amount of oxygen dissolved in it
  • Insufficient to provide body's normal needs
• Type 1 respiratory failure:

  • Low pO2 - low amount of oxygen dissolved in the blood
• Type 2 respiratory failure:

  • Low pO2 and high pCO2 - low amount of oxygen in the blood and high amount of carbon dioxide dissolved in the blood
• Type 2 respiratory failure:

  • Low pO2 and high pCO2 - low amount of oxygen in the blood and high amount of carbon dioxide dissolved in the blood
  • In susceptible patients (such as those with COPD) high flow oxygen can push up the amount of pCO2 in the blood, and when it dissolves the blood can become acidic, and this is associated with an increased risk of death
• Type 2 respiratory failure:

  • Some pts can compensate for increased acidity of the blood in terms of how they breath & their kidneys - but pts with COPD can't compensate as well & can't blow off the CO2
  • So the pCO2 in their blood will be high & they're at risk of developing acidaemia (acidic blood) -> means a higher risk of death
  • Can be precipitated by giving pts high flow O2
  • If you give a pt with COPD a large amount of O2 -> can push up CO2 in the blood - that CO2 then dissolves in the blood & becomes acidic -> increased risk of death - therefore be cautious when giving O2 to pts with COPD 
• LTOT (long-term oxygen therapy) is indicated in pts with COPD:

  • PaO2 < 7.3 kPa when stable or
  • PaO2 < 8 kPa when stable and one of:
  • Secondary polycythaemia (high concentration of red blood cells in the blood)
  • Nocturnal hypoxaemia (oxygen saturation of arterial blood [SaO2] less than 90% for more than 30% of time)
  • Peripheral oedema
  • Pulmonary hypertension
  • In the above, the pt's amount of oxygen has been carefully calculated, so they should already be on an appropriate amount of oxygen - do not increase the oxygen without good cause!
• The pt that you are seeing may not know they have COPD:

  • Do they smoke
  • If they don't smoke then it's unlikely that they will have COPD
  • How far can they walk on the flat unaided (eMRCD score)
  • eMRCD score can grade a pt's level of breathlessness
  • How fast are they breathing? Is their breathing laboured? Do they have a blue discolouration to their lips
  • Fast breathing can indicate an underlying breathing problem
  • Check oxygen saturations
• Oxygen in COPD:

  • If in doubt, aim to keep oxygen stats 88-92%
  • Oxygen is a treatment for low oxygen levels, not for panic or breathlessness