The breathless Patient Flashcards
What are the different categories of causes of breathlessness?
The following four are classified as respiratory:
Airways
Tissue
Perfusion
Other
Non-respiratory
What are some airway related causes of breathlessness?
COPD
Asthma
Bronchiectasis
Anaphylaxis
What are some tissue related causes of breathlessness?
Interstitial Lung disease
What are some perfusion related causes of breathlessness?
V/Q mismatch
PE
PA Hypertension
What are some general respiratroy related causes of breathlessness?
Pleural effusion
Pneumonia
Lung Cancer
What are some non-respiratory causes of breathlessness?
Anaemia
Acidosis
Diaphragm splinting e.g in pregnancy
Cardiac tamponade
Arrhythmia
Anxiety
Heart Failure
MI
Acidosis
Define breathlessness
A subjective, distressing sensation of awareness of difficulty with breathing.
At what point can oxygen delivery go wrong?
- From outside world to the alveolar capillaries
- Taken up by Hb in RBCs
- Transported to areas of oxygen demand
- Used by cells in respiration
What is the main cause of breathlessness?
Hypoxia
What are the four different types of hypoxia?
Hypoxic hypoxia
Anaemic hypoxia
Stagnant hypoxia
Histotoxic Hypoxia
What is hypoxic hypoxia?
Not enough oxygen getting into the blood from the environment
Either problem with environment or problems getting into lungs (grossly)
Examples = high altitude, hypoventilation, V/Q mismatch
Pathology = COPD, PE, etc
What is anaemic hypoxia?
Insufficient Hb to collect oxygen to carry in the blood.
Examples - carbon monoxide poisoning, iron deficiency anaemia, haemorrhage
What is stagnant hypoxia?
Oxygen in blood is ineffectively circulated to areas of demand
For example - heart failure, Raynauds syndrome, Buergers disease
What is histotoxic hypoxia?
Sufficient oxygenation to tissues however cells cannot use it.
Main example is cyanide poisoning also alcohol, acetone some narcotics
Define cyanosis
The blue or purplish discolouration fo the skin or mucous membrane due to the tissues near the skin having loss oxygen saturation.
Can be central or peripheral
What are the main causes of central cyanosis?
Major causes of hypoxia/ hypo-perfusion, blood leaving heart is insufficient of oxygen
Generalised discolouration of he body and visible mucous membranes
Resp - COPD, pneumonia, PE
Cardio - HF, Cong HD
CNS - Drug overdose, ICH
What are the main causes of peripheral cyanosis?
Any causes of central cyanosis and when blood ‘can’t reach edges’ or is insufficient of oxygen in the periphery
Mucous membranes are not affected.
Reduced cardiac output - shock (septic or hypovolemic)
Hypothermia - peripheral vessels constrict (common in elderly)
Arterial/venous obstruction
What are the different types of masks/methods that can be used to administer oxygen?
Nasal cannula
Venturi mask
Simple Mask
Non- rebreathe mask
How much oxygen can a nasal canula deliver?
Connected to oxygen at the wall - due to nature of mask and likelihood to be not be in correct position is considered a variable performance device
1L = 24%
2L = 28%
3L = 32%
4L = 36%
4L is the max
What is the basic idea of how a venturi mask works?
Coloured clip at the bottom of the mask - controls how much additional air is entrained into the mask. Links to how many litres should be administered from the wall.
Can be connected to other devices such as a neb
Provides accurate levels of oxygen - high control.
What are the different colours of a venturi mask related to how much oxygen they adminster?
Blue = 24%
White = 28%
Yellow = 35%
Red = 40%
Green = 60%
(Boy wants your rosy girl)
What is the basic idea of how a simple mask works and how much oxygen can you deliver?
Connect to any flow of oxygen from the wall
Uncertain amount of additional air breathed in by the patient
Can connect to other devices such as nebs
Highly variable between 1-15L or 24%-60% oxygen
What are the basic principles of how a nonbreathe mask works and how much oxygen can it deliver?
Delivers an accurate and high percentage of oxygen
Between 10L or 60% and 15L 90%
Has an oxygen reservoir back at the bottom to maximise how much oxygen goes into the patient.
What is the normal target oxygen saturation?
94-98%
What is the target oxygen saturation in most patients with COPD/hypoventilation risk?
How do you identify these patients?
88-92%
Are chronic CO2 retainers - so have elevated CO2 and HCO3- on an ABG
High flow may be given is profoundly hypoxic and breathless - call for a senior immediately.
Explain why patients with COPD have lower target oxygen saturation than normal.
Chronic CO2 retainer - hyperventilation response to CO2 becomes less sensitive
Rely on hypoxic respiratory drive
Adminstering uncontrolled oxygen - lose hypoxic drive become bradypnoeix
Inc CO2 - disregulated acid base levels.
What is the target oxygen saturation in MI patients?
Normal 94-98%
Oxygen should not be given if SATs are within the normal range.
Define hyperventilation
When the rate or tidal volume of breathing eliminates more CO2 than the body can produce.
What are some common causes of hyperventilation?
Physiological stress (inc CO2 prod by cells)
Anxiety/panic
Acidosis - DKA, Lactic acidosis
Head injury/brain injury
Respiratory disease - asthma, COPD, pneumonia
Cardiovascular disease - heart failure/anaemia
What are the key signs and symptoms of hyperventilation?
Dizziness
Breathlessness
Palpirations
Numbness.
Fall in Co2, cause resp alkalosis is sustained, HR inc to match the V?Q ratio, as CO2 falls this can cause dizziness and peripheral paraesthesia.
Define cough
A reflexive action designed to protect the lungs from damage - either chemical or physical.
What are some common causes of cough?
Upper RTI
Adverse medication effects ACEi
Acid reflux
Lung cancer/PE (hemoptysis)
Pulmonary disease - ILD
Airway disease (Asthma)
What are some examples of factors that can activate the sensory nerve fibres to create a cough?
Mechanical - foreign body or cancer
Chemical - histamine, bradykinin, LTO4.
Give a basic understanding of the neural activity of the cough reflex.
Mechanical/chemo stimuli acts on mechano/chemoreceptors in the respiratory mucosa
Sensory afferent pathway - electrical activity travels along the vagus nerve
Synapse in the Nucleus tractus Solitarus in the medulla
Activates multiple efferent nerve fibres (phrenic, spinomotor, recurrent laryngeal, vagus)
Acts on effector muscles (respiratory, laryngeal and bronchial smooth muscle)
What are the different phases of the cough impulse?
Inspiratory phase
Compression
Expiratory phase
What happens in the inspiratory phase of the cough reflex?
Take a large breath in
Stretch expiratory muscles
Inc pressure in the lungs
What happens in the compression phase of the cough reflex?**
Glottis and vocal cords closes
Expiration Respiratory muscles contract - expiration against the closed glottis
Further inc in pressure in the lungs
What happens in the expiratory phase of the cough reflex?
Glottis open
Due to high pressure in lungs - air leaves rapidly down pressure gradient creates a bang as passes through the vocal cords.
What are some examples of different types of cough?
Barking = croup (upper air-way obstruction)
Hunking - psychogenic
Paroxysmal = bronchitis - violent uncontrolled fits
Wet = suppurative lung disease
Dry = asthma.
