Week Three - Chronic Breathlessness Flashcards
what is bronchitis
an inflammation of the bronchi in the lungs
this causes a narrowing of the airways due to a combination of tissue swelling and excess mucus production
what are the features of acute bronchitis
cough (chesty)
- often productive of sputum - typically clear, yellow or green coloured
- dark brown or grey coloured may be more suggestive of a true pneumonia
fever
cough lasting about two weeks
generally no treatments speed up recovery
what is bronchitis typically caused by
respiratory tract infections (usually viral), or chronic which is typically associated with COPD
what does pulmonary hypertension refer to
increased resistance and pressure in the pulmonary arteries
where does pulmonary hypertension cause strain
on the right side of the heart as it tries to pump blood through the lungs
there is back pressure through the right side of the heart and into the systemic venous system
what is pulmonary hypertension defined as
a mean pulmonary arterial pressure of more than 20mmHg
what are the five groups of causes of pulmonary hypertension
Group 1 - idiopathic pulmonary hypertension or connective tissue disease (e.g systemic lupus erythematous)
Group 2 - left heart failure usually due to myocardial infarction or systemic hypertension sion
Group 3 - chronic lung disease (COPD or pulmonary fibrosis)
Group 4 - pulmonary vascular disease (PE)
Group 5 - miscellaneous
what are the signs and symptoms of pulmonary hypertension
shortness of breath is the main presenting symptom
Syncope (loss of consciousness)
Tachycardia
Raised jugular venous pressure (JVP)
Hepatomegaly
Peripheral oedema
what will an ECG show in pulmonary hypertension
indicate right sided heart strain
- P pulmonale (peaked P waves)
- right ventricular hypertrophy (tall R waves in V1 and V2 and deep S waves in V5 and V6)
- right axis deviation
- right bundle branch block
what are the changes seen on CXR
- dilated pulmonary arteries
- right ventricular hypertrophy
what are the other investigations done for pulmonary hypertension
Raised NT‑proBNP blood test result indicates right ventricular failure
Echocardiogram can be used to estimate the pulmonary artery pressure
what is idiopathic pulmonary hypertension treated with
calcium channel blockers
IV prostaglandins (epoprostenol)
Endothelin receptor antagonists (macitentan)
phsophodiesterase-5 inhibitions (sildenafil)
what does asbestosis refer to
lung fibrosis related to asbestos exposure
what does asbestos inhalation cause
Lung fibrosis
Pleural thickening and pleural plaques
Adenocarcinoma
Mesothelioma
what is the normal pH value on ABG
7.35-7.45
what is the normal PaCO2 value in an ABG
4.7-6.0 kPa / 35-45 mmHg
what is the normal PaO2 value in an ABG
9.3-13.3 kPa / 80-100 mmHg
what is the normal HCO3- value in an ABG
22-28 mmol/L
what is the normal SaO2 in an ABG
92-98%
what is PA
pressure in the alveoli
what is Pa
pressure in the artery
what is the mechanism of respiratory compensation
If the concentration of Hydrogen ions increases, the pH will decrease, causing an acidosis. This causes the equation to shift to the left, and more CO2 is produced, of which some (or all) can be blown off by the lungs. This is the mechanism of respiratory compensation.w
what is partial respiratory compensation
If CO2 is not able to blown off effectively, then the concentration of CO2 increases, as thus then so will the concentration of hydrogen ions, and the pH will not be able to be resolved to normal. This is partial respiratory compensation.
what are most causes of acid-base disturbance due to
an acidosis.
what’s metabolic compensation
There can also be metabolic compensation whereby the concentration of HCO3 is altered to try to keep the equilibrium in cases of respiratory dysfunction.
what happens in respiratory alkalosis
In a respiratory alkalosis, CO2 is blown off too quickly, thus the curve shifts to the left, to replace the CO2, and the concentration of hydrogen ions is lowered
what happens in metabolic alkalosis
In a metabolic alkalosis there is a disturbance due a loss of H+ or an excess of HCO3, causing the curve to shift.
what chronic and acute factors in a patient’s history can affect ABG
renal diseases
diabetes
drugs - diuretics and aspirinw
what is the rule of 19
The Rule of 19 is a way of assessing whether or not the patient was on oxygen at the time of the sample. Add the PO2 and PCO2 – if the sum of these is >19 then likely to be on inspired oxygen. If the level is lower than this, they are likely to be breathing room air.
what are the basic ABG interpretation rules
- Look at the pH – is it acidosis, alkalosis, or normal?
- If its acidotic, then the patient is acidotic
If acidotic, calculate the anion gap to help differentiate the cause
- If its alkalotic, the patient is alkalotic
- If its it normal, there may be no acid-base dysfunction, or the patient could have a compensated acidosis or alkalosis. The CO2 and HCO3 values are required for further interpretation. - Look at the CO2 – is it normal or abnormal? Is this change in keeping with the pH? (See table below)
- Look at the HCO3- – is it normal or abnormal? Is the change in keeping with the pH?
A. Note the changes in bicarb and base excess take at least a couple of days to occur after the initial causatory event. - If the changes aren’t in keeping with the levels, then it is likely to be some sort of compensation! More on how to tell this later on.
what does
↔ CO2 ↔ pH
mean
normal acid base status
what does
↔ CO2 ↓ pH
mean
Metabolic Acidosis
what does
↔ CO2 ↑ pH
mean
metabolic alkalosis
what does
↑ CO2 ↔ pH
mean
respiratory acidosis with full metabolic compensation
what does
↑ CO2 ↓ pH
mean
respiratory acidosis
what does
↑ CO2 ↑ pH
mean
metabolic alkalosis with partial respiratory compensation
what does
↓ CO2 ↔ pH
mean
respiratory alkalosis with full metabolic compensation
what does
↓ CO2 ↓ pH
mean
Metabolic Acidosis with partial respiratory compensation
what does
↓CO2 ↑ pH
mean
metabolic alkalosis with partial respiratory compensation
what is respiratory acidosis due to
Respiratory acidosis is very straightforward. It is always due to a retention of CO2, (Type II Respiratory failure)
what are the causes of retention of CO2
COPD
Depressed respiratory drive (e.g. low GCS)
Brain Injury
Drug overdose (often opiates)
CO2retention in COPD patients causing worsening drowsiness
Hypoventilation of any other cause
what are the signs of CO2 retention
Confusion – as a result of peripheral vasodilation
Asterixis (renal failure, type 2 resp failure, liver failure)
Warm extremeties
Bounding pulse
Morning headache – CO2 particularly high at these times.
what is the 1 for 10 rule
ACUTE: For every rise of 10 of the PaCO2 above 40 mmHg, the bicarbonate will rise by 1
CHRONIC: For every rise of 10 of the PaCO2 above 40mmHg, the bicarbonate will rise by 4
what is respiratory alkalosis due to
due to hyperventilation
explain respiratory alkalosis and the causes associated
As PaCO2 lowers, so pH rises
Any cause of hyperventilation:
Anxiety
Pain
Fever
Sepsis
Hypoxia (due to acute illness (sepsis / pneumonia) or altitude)
what is metabolic alkalosis caused by
Loss of hydrogen ions
- Diarrhoea (sometimes vomiting too)
- Burns
Excess Bicarbonate
- Diuretics
- Ingestion of alkaline substances
what is the most common cause of hydrogen ion loss
diarrhoea
. In diarrhoea, there is a loss of K+ into the GI tract. This causes K+ to leave cells, and enter the bloodstream in an attempt to keep K+ levels normal. In order to maintain the electrical charge of the cell, H+ is then taken up by the cell.
what is the usual cause for excess bicarbonate
Normal kidneys are very effective at excreting bicarbonate. Diuretics prevent the re-absorption of sodium from the renal tubule, and thus they promote sodium loss. The normal mechanism for recovering this sodium, involves an exchange with bicarbonate, and thus the ability of the renal tubule to excret bicarbonate is reduced.
look up the variety of causes of metabolic acidosis on almost a doctor
You are undertaking a medication review on one of your patients in a GP surgery who has COPD. You note that the latest spirometry shows an FEV1 of 59%. The patient is already taking salbutamol prn. What other medications should be considered at this point?
- salbutamol inhaler
- tiotropium inhaler
what do these ABG results show?
- FiO2 35% oxygen via venturi mask
- SaO2 98%
- pH 7.31
- pCO2 7.8 kPa
- pO2 13.6 kPa
- HCO3 22.1 kPa
- BE -4.5
uncompensated type II respiratory failure
What is the mechanism of action of Aminophylline?
phosphodiesterase inhibitor
A 65 year old man with a 30 pack year smoking history presents to the GP complaining of persistent shortness of breath over the past 2 years. He also has a regular and productive cough. He has no fever or recent travel history. Which examination findings will most likely be seen in this patient?
hyper-resonant percussion note, polyphonic wheeze
Which of the following fulfil criteria for LTOT?
PaO2 7.2kPa
what is the best investigation for sarcoidosis
bronchoscopy with biopsy EBUS
A 57 year old male with presents with shortness of breath and weight loss. He has finger clubbing and fine crepitations. CXR shows bilateral reticulonodular shadowing. HRCT is performed to confirm the diagnosis. What would confirm the most likely diagnosis?
honeycombing
A 76 year old lady is diagnosed with pulmonary fibrosis. Her PMHx includes HTN, Afib, recurrent UTIs and osteoarthritis with bilateral hip replacements. Which drug is most likely to have contributed to her diagnosis?
Nitrofurantoin
methotrexate is used in rheumatoid arthritis, not osteoarthritis
