Respiratory Flashcards
What is type 1 respiratory failure?
Hypoxic on room air PaO2 < 8kPa and normal or low PaCO2. Ventilation profusion mismatch
What is type 2 respiratory failure?
Hypoxic on room air PaO2 < 8kPa and raised CO2 >6kPa. ventilatory failure
What are some causes of respiratory failure?
Acute asthma, exacerbation of COPD, PE, pneumonia, Pulmonary oedema, opiate or benzodiazepines overdose, guillian barre syndrome
What might you give in opiate overdose?
Naloxone 400mcg IV bolus ± IV Flumazenil 200mcg over 15s
What is a genetic cause of COPD?
Alpha 1 antitrypsin deficiency
A seriene protease inhibitor
Panacinar emphysema
What is Chronic Bronchitis?
Production of sputum for most days for at least 3 months in at least 2 years. Productive cough and lots of mucus. Elevated Hb (polycythaemia)
What type of respiratory failure happens in chronic bronchitis?
Type 2 - Low respiratory drive
hypoxic and hypercapnia. Loss of central sensitivity to CO2 and so reliant on hypoxia to stimulate breathing. aim for 88-92%
What is Emphysema?
Abnormal, permanent enlargement of the airspaces distal to the terminal bronchioles. Elasticity reduced and alveoli collapse - Air trapping
What type of respiratory failure occurs in emphysema?
Type 1 - hight respiratory drive
Hypoxia due to air trapping and hyperinflation of the chest - inefficient gas exchange.
Desaturate on exercise
What is panacinar emphysema?
Uniform enlargement from the level of the terminal bronchiole distally
What might be seen on spirometry in COPD?
Obstructive pattern
FEV1/FVC < 70%
What is first line in COPD management?
SABA - Salbutamol or
SAMA - Ipratropium
What other treatment would you give a COPD patient on SAMA or SABA who is still symptomatic?
Add LABA or
Stop SAMA and add LAMA
If further exacerbations - ICS - prednisolone or budesonide.
If further exacerbations consider -
Oral Theophylline, Roflumilast, azithromycin, Carbocisteine.
What is COPD?
Airflow obstruction that is usually progressive and not usually reversible, it does not change markedly over several months
What are some symptoms of an exacerbation of COPD?
Increasing cough, breathlessness, impaired consciousness, wheeze, decreased exercise capacity
What is the criteria for hospital admission in an exacerbation of COPD?
Marked increase in symptoms
New physical symptoms (cyanosis, peripheral oedema)
Significant co-morbidities
Not responding to initial management at home
> 70
Inadequate home support
In a COPD exacerbation, if there is no response to NIV or mechanical ventilation, what can you use?
Respiratory stimulant - Doxapram IV 1.5-4mg
How would you treat an acute exacerbation of COPD?
- Nebulised bronchodilators (Salbutamol 5mg/4h or ipratropium bromide 500mcg/6h)
- Controlled oxygen therapy - aim for 88-92%
- Steroids - IV hydrocortisone 50-100mg or oral prednisolone 30mg
- Antibiotics - amoxicillin 500mg/8h or clarithromycin 500mg or doxycycline 200mg
- Physiotherapy to aid sputum expectoration
IF NO RESPONSE - IV aminophylline
IF NO RESPONSE - a. NIV if RR > 30 pH < 7.35
b. Intubation and ventilation if paCO2 still rising with NIV pH <7.26 - Consider a respiratory stimulant - Doxapram 1.5-4mg
also may need to give enoxaparin 40mg
What is asthma
Inflammation of the airways characterised by intermittent airflow obstruction, hyper-responsive airways and reversible airflow obstruction
How do you define reversible airflow obstruction.
An improvement in FEV1 of >/=15% or 400ml after 5mg of nebulised salbutamol
Define a positive bronchial hypersensitivity test.
A fall in FEV1 by 20% after less than 8mg/ml of methacholine (or histamine or mannitol)
How does salbutamol/terbutaline work and what are potential SE?
Relaxes bronchial smooth muscle via increasing cAMP.
SE - tremor, hypokalaemia, hyperglycaemia, muscle cramps
What is the management options in asthma?
- SABA
- SABA + low dose ICS
- SABA + low dose ICS + LABA
- SABA + LABA + Medium dose ICS
- SABA + LABA + high dose ICS
How so SA and LA muscarinic antagonists work?
Works on M1 and M3
M1 counteracts bronchconstriction directly
M3 causes NO release - vasodilation
Nebulised risk of Acute angle closure glaucoma
What are methylxanthines MoA?
Relax bronchial smooth muscle, improve mucocillary clearance and have an anti-inflammatory effect
In an acute asthma attack 2g of magnesium sulphate may be given over 2 min. What is its MoA?
relaxes bronchial smooth muscle. Blocks histamine production from mast cells, reduces Ach production from nerve endings
SE. hypermagnesamia, muscle weakness, respiratory failure.
What monoclonal antibodies can be used as maintenance drugs in asthma?
Omalizumab - anti IgE - reduces circulating IgE. SC injection every 4 weeks
Mepolizumab - anti- IL5, reduces circulating eosinophils. SC injection every 4 weeks.
Given an example of the maintenance drug Leukotriene receptor antagonist and its MoA?
Montelukast and Zafirlukast
Reduces airway oedema and smooth muscle contraction
How would you manage life threatening asthma?
silent chest, low respiratory effort, PEF <33% predicted, sats <92%, altered consciousness, agitation/confusion
O SHIT ME
- High flow oxygen - aim >/=92%
- Nebulised salbutamol 500mg
- IV hydrocortisone 100mg or oral prednisolone 40mg
- Ipratropium bromide 500mcg
- Theophylline IV
- Magnesium sulphate 2g over 2 min
- Escalate care - intubation and ventilation
If chest infection suspected - Doxycycline 200mg Oral
What is brittle asthma?
A rare form of severe asthma that is hard to control due to being unstable or unpredictable.
Type 1: wide variation of PEF despite intense and regular therapy
Type2: sudden severe asthma attacks on a background of apparently well controlled asthma
What is near fatal asthma?
Raised PaCO2 ± the need for mechanical ventilation with raised inflation pressures.
What are some characteristics of severe asthma?
PaO2 <92% PEF 33-50% predicted Too breathless to talk or feed RR >30 HR >125 use of accessory muscle audible wheeze
What are some characteristic of life threatening asthma,s?
PaO2 <92%
PEF < 33% predicted
Silent chest, agitated, confused, cyanotic, poor respiratory effort, altered consciousness, exhaustion
What are some antibiotics that can be takes in a suspected chest infection in an asthmatic?
Amoxicillin 500mg/8h Orally or 1g/8h IV. Caution in renal problems as renal excreted.
Co-moxiclav 625mg/8h Orally or 1.2g/8h IV. Caution in Renal impairment as renal excreted
Clarithromycin 500mg /12h orally (IV causes phlebitis). Caution in hepatic impairment and renal impairment. Risk of adverse drug reactions - Can’t Give with methlyxanthines, cardiac caution (QT prolongation)
Doxycyline 200mg then 100mg orally - Caution in hepatic impairment. Avoid in children or pregnant women
What symptomatic triad may be present in acute severe asthma?
Wheeze
Increasingly breathless
Cough
What is obstructive sleep apnoea?
Recurrent episodes of complete or partial upper airway (pharyngeal) obstruction during sleep, with intermittent hypoxia and sleep fragmentation
Define apnoea.
Cessation or near cessation of airflow. 4% o2 desaturation lasting >/=10s