General Clinical Flashcards
True or False: There are pain receptors in the lungs
False, they are asensate
Why do people get breathless?
Demand increases and is higher than supply of O2
PND
Paroxysmal Nocturnal Dyspnoea
What are some of the sinister causes of cough?
• Lung cancer • Mesothelioma • Pulmonary metastases • Pulmonary fibrosis • Sarcoidosis • Pneumonitis
What are the ‘big 4’ causes of haemoptysis?
• Infection • Carcinoma • Pulmonary Embolism • Bronchiectasis
Blood
A specialised fluid composed of cells suspended in plasma
What is blood composed of?
- Plasma - White cells - Platelets - Red blood cells
What are the majority of blood cells made?
Bone marrow
What is contained at the centre of the haem group?
Iron atom
True or False: iron deficient red cells are smaller
True, lack of iron leads to a reduction in Hb
Which protein is responsible for the storage of iron?
Ferritin
What causes an increase in neutrophils?
Stress: physiological or pathological (acute infection, trauma, infarction, inflammation)
What causes an increase in eosinophils?
• parasitic infections • hypersensitivity/allergic reactions
What causes an increase in basophils?
Hypersensitivity reactions
What causes an increase in monocytes?
• chronic infections, malignancy, autoimmune disorders
What causes an increase in lymphocytes?
• Viral infections
D-dimer
Fibrin degradation product - if increased suggest increased fibrinolysis following increased fibrin deposition
Plasma viscosity (PV)
an index of changes in plasma proteins (reactant fibrinogen and some globulins). Changes in plasma viscosity can reflect systemic inflammation, and less commonly, haematological malignancies producing an abnormal protein.
Type I Respiratory Failure
A low level of oxygen in the blood (hypoxemia) without an increased level of carbon dioxide in the blood (hypercapnia)
Type II Respiratory Failure
Hypoxemia (PaO2 6.0kPa). Respiratory centre becomes insensitive to CO2 and respiration could be driven by hypoxia, rather than hypercapnia
What are the reasons that people retain carbon dioxide?
- Reduced hypoxic drive: Respiratory centre becomes desensitised to CO2 and respiration could be driven by hypoxia - V/Q mismatching: Normally areas of poor ventilation have reactive vasoconstriction, but if you give them excess oxygen, then reactive vasoconstriction is reversed and this area is perfused so CO2 struggles to leave - Haldane effect: Chronically hypoxaemic patient has low Hb saturation, which increases Hb affinity for CO2
What are 5 underlying causes of hypoxia?
- Circulatory hypoxia: oxygenated blood can’t get to the tissues - Anaemic hypoxia: no Hb to carry the oxygen - Toxic hypoxia: prevention of oxygen binding to Hb - Hyperaemic hypoxia: lungs dont work, can be due to low inspired oxygen concentration (eg. altitude), alveolar hyperventilation or impaired diffusion, shunting, V/Q mismatch or dead space - Alveolar hypoxia: inability to breathe eg. obesity, anaesthesia
Shunting
Good perfusion but bad ventilation eg. lung diseases
Dead space
Good ventilation but bad perfusion eg. circulatory disorders such as PE or hypertension
Ventilation perfusion mismatching
Areas of lung disease have varying degrees of perfusion and ventilation, and perfusion should be directed to areas of best ventilation, though this can be mismatched. • Lung apex: Good V, Poor Q • Lung base: Poor V, Good Q
True or False: Oxygen is the treatment for breathlessness
False, oxygen is the treatment for hyperaemia
Headache on waking and obese
CO2 retention
Daytime solomence (falling asleep during the day) and headaches
Sleep apnoea
What can cause a CO2 retention headache?
- Sleep apnoea - Obesity hypoventilation - Cystic fibrosis - Kyphoscoliosis (Basically any cause of chronic type II respiratory failure will be worsened at night)
25y woman, SOB with RR of 25. Carries a bag of drugs eg. antibiotics and steroids
Likely cystic fibrosis
25y woman, SOB with RR of 25. Productive green cough past few days with raised temp
Likely pneumonia
25y woman, SOB with RR of 25. Fell of a horse a few days ago
Likely pneumothorax
25y woman, SOB with RR of 25. Wheeze, using accessory muscles and unable to complete sentences
Likely Asmtha
Which lung cancers are generally central?
Squamous
Which lung cancers are generally peripheral?
Adenocarcinoma
What are the 3 types of pulmonary function tests?
1) Effort dependent tests (dynamic lung volumes) 2) Effort independent tests (static lung volumes) 3) Gas diffusion tests
What are effort dependent tests and give examples?
(dynamic lung volumes). Those which involve maximal effort eg. forced expiratory volumes and flow rates (spirometry). Measures the the lung volume and the flow rate (liter per second). Purest measure of obstruction of airflow throughout the bronchial tree.
What is spirometry and what does it measure?
The most common of the pulmonary function tests (PFTs), measuring lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Essentially testing the functional lung volumes. It measures: FEV1 and FVC (and therefore FEV1/FVC) from a single forced expiration until no more breath left.
What are effort independent tests and give examples?
(Static lung volumes) Dont involve forced expiration. For example: relaxed vial capacity, impulse oscillometry, helium/N2 washout static lung volume
What are gas diffusion tests and give examples?
Test diffusion of gas across the alveolar and vascular bed eg. ABGs, or SaO2 during exercise
FEV1
Forced Expiratory Volume in 1 sec - The volume of air that can forcibly be blown out in one second, after full inspiration
FEV1/FVC or FEV1%
Forced Expiratory Ration (FER) - Proportion of total FVC expired in the 1st second of expiration
FVC
Forced vital capacity - the volume of air that can forcibly be blown out after full inspiration
PEF
Peal expiratory flow - the maximal flow (or speed) achieved during the maximally forced expiration initiated at full inspiration, measured in liters per minute
TV
Tidal volume - the amount of air inhaled and exhaled normally at rest.
TLC
Total lung capacity - the maximum volume of air present in the lungs
What is the difference in spirometry results for COPD and asthma (probable exam Q)?
Asthma: FVC is preserved, however it takes longer to reach it due to narrowing of airways, so FEV1:FVC is lower
COPD: Lots of air is trapped in the lungs to FVC is reduced and FEV1:FVC is also reduced
What are normal results on spirometry?
FEV1 = ~4l
FVC = ~5L
FEV1/FVC = 75-80%
What is an obstructive picture on spirometry eg. asthma/COPD?
- FEV1 = Reduced (1.3L)
- FVC = Reduced (3.1L - <80% of normal)
- FEV1/FVC = Reduced the most (<75%)
- PEFR = reduced
Main issue is the obstruction to airflow, so air has more to overcome to get out
What is a restrictive picture on spirometry eg. fibrosis?
- FVC = reduced (2.8L)
- FEV1 = reduced (3.1L)
- FEV1/FVC = normal or slightly increased (>75%)
- PEFR = normal
*FVC and FEV are reduced proportionatly*
Main issue is the lungs are reduced in volume or less compliant, however air can still get out. So the ratio is normal or increased as the reduction in volume is much more substantial
What are the 3 shapes on the expiratory flow -volume curves, measured by PEFR - and what are the conditions associated with each?
- Normal
- Volume dependent expiratory airway closure – Asthma progressively close airways on expiration, creates wheeze.
- Asthma, chronic bronchitis
- Pressure dependent expiratory airway closure
- Emphysema
Diffusion capacity-transfer factor (DLCO)
The carbon monoxide uptake from a single inspiration in a standard time.
Inhale known concentration of CO then exhale , can estimate the diffusion capacity. This is a sensitive measure for alveolar arteriolar vascular bed.
What conditions can cause a reduced Diffusion Capacity (DLCO)?
Anaemia, Emphysema, Intersitial lung disease, Pulmonary oedema, Po emboli, Bronchiectesis
Which 2 ways can airway resistance be measured?
By either whole body plethysmography (body box) or more commonly/easily with impulse oscillometry
Impulse oscillometry (IOS)
Measures airways resistance during quiet tidal breathing - at different resonant frequencies to give total resistance (@ 5Hz) and central resistance (@20Hz) - and hence peripheral airway resistance by subtraction R5-R20.
What are the main differences betweenn restrictive and obstructive spirometry?
- FVC is normal (asthma)/slightly reduced (COPD) in obstructive, but reduced in restrictive
- FEV1/FVC% is substantially reduced in obstructive but normal or increased in restrictive
- PEFR is redued in obstructive and normal in restrictive
- Gas transfer (DLCO/TLCO) is reduced in obstructive, and only reduced in restrictive if there is disease in the alveolar walls
What is the average VO2?
45ml/kg/min
What are causes of immediate breathlessness?
§Pneumothorax
§PE
What are causes of acute (min-hours) breathlessness?
- Asthma
- Pneumonia
- Acute MI
- Cardiac tamponade
What are subacute (days) causes of breathlessness?
- Plerual effusion
- Pulmonary vasculitis
- Superior Vena Cava obstruction
What are chronic (months-years) causes of breathlessness?
- COPD
- ILD
- Pulmonary Hypertension
- Anaemia
What are the possible sources of breathlessness?
- Lung parenchyma
- Airways
- Pleura
- Diaphragm
- Obesity
- Vasculature – pulmonary emboli/hypertension
- Muscle/nerves/bones – e.g. in MND where intercostal muscles don’t work
- Brain (respiratory drive)
What are the 3 udneryling processes that can cause breathlessness?
- Reduced ventilation
- Reduced perfusion
- Reduced as transfer
What are some of the non-respiratory causes of breathlessness?
- -Pain
- Take small breaths to minimise pain
- -Respiratory compensation for Metabolic Acidosis
- Diabetic ketoacidosis
- -Anxiety
What are some of the causes of breathlessnes by reduced gas transfer?
- CF
- Pulmonary fibrosis
- Neonatal respiratory distress syndrome
- Pulmonary oedema
- CO poisoning/cyanide/arsenic
- TB
