Critical care Flashcards
How is Critical care defined?
Organ system support - this can be a single organ or multiple
What are the Levels of care and where does critcal care fit in with this?
- Level 1 = ward based care where the patient does not require organ support (for example, they may need an IV, or oxygen by face mask)
The following are critical care:-
- Level 2 = High dependency unit (HDU). Single organ support such as renal haemofiltration or ionotropes and invasive BP monitoring.
- Level 3 = Intensive care. Multiple organ support (or needing mechanical ventilation alone)
However, this is not as clear cut as you think. For example a Respiratory ward can give ventilation and a Renal ward can do dialysis.
What is the difference between Respiratory failure Type 1 and Type 2?
- Type 1: oxygenation failure
- Type 2: oxygenation and ventilation failure
When delivering O2 to a patient, what does the % of oxygen inspired depend on? (2)
- Flow rate
- This can be set on the wall tap: it varies from 0 – 15L per minute
- Delivery device - these work with different flow rates
How can O2 be given to non-acute/ acutely unwell patients in a general ward?
- Nasal cannulae - this air is not humidified however – 2-4 litres O2 into nose which is approx. 30% O2 - can’t give more than this because it involves blowing a lot of cold and dry air into the nose – becomes uncomfortable
- Hudson face mask – (rarely used) 4-10 litres a minute – approx. 40% O2
- Trauma mask – up to 90% O2 if working well
How is O2 usually given to patients with type 1 respiratory failure in general wards?
In critical care, O2 is given via a HFT (high flow therapy) Nasal Cannula. This cannula is attached to a humidifier.
- It delivers a high flow (liters per minute) of gas to a patient.
- The gas is humidified which means you can deliver more O2 (can go up to 70 litres/min).
- This bulk flow of gas has a pressure effect in the patient’s airways which improves the work of breathing and opens the airways to get air in
- Due to the high flow rates it doesn’t matter how fast or deeply the patient is breathing, the patient will receive the 100% O2 if you give it
How is O2 given to patients with type 2 respiratory failure in critical care?
Non-invasive ventilator (NIV) or CPAP
- This is usually used for COPD patients that are retaining CO2 and require supportive ventilation to overcome whilst avoiding intubation
- The machine applies positive airway pressure to keep airways open and support patient’s breathing (reduce effort/work of breathing)
Invasive ventilation
- Patient is intubated and this is attached to a ventilator machine or bag which ventilates the lungs for them - it is a closed system
- This is used in intensive care and theatre
- Fully controlled oxygen delivery up to 100%
If the patient is not improving on a ventilator what can you do?
- They may require prolonged ventilation
- Do this by performing tracheostomy - hole in the neck that the tube is put through
- This bypasses the oropharynx and therefor bypasses the need for sedation and the inability to eat/swallow/mouth words.
How is ‘shock’ defined?
Shock is acute circulatory failure with inadequate or inappropriately distributed tissue perfusion resulting in cellular hypoxia
To treat that you need to get blood pumping round the body again and into these tissues.
Different types of shock
- Septic (distributive) – bacteraemia and respiratory distress - blood vessels abnormally dilated due to inflammatory response leading to abnormal fluid distribution
- Hypovolaemic
- Anaphylactic
- Neurogenic – relates to trauma to spinal cord – destruction of sympathetic N.S causes abnormal vasodilation within the tissues and periphery
- Cardiogenic
What are the 2 most common classes of drugs given in critical care to deal with cardiovascular failure?
- Vasopressors
- Inotropes
Vasopressors and CV failure
Most commonly used to treat septic shock
- Metaraminol - alpha 1 agonist with a little beta activity – creates vasoconstriction which leads to increased total peipheral resistance (TPR). Increasing the TPR leads to increased mean arterial pressure (MAP) and increased perfusion to organs
- Noradrenaline – more potent (less drug required to achieve same effect) must be given through central line though because of this. Increases cardiac contractility which improves cardiac output (CO), aiding in maintaining MAP and perfusion to the body.
What is preload?
Preload is the initial stretching of the cardiac myocytes (muscle cells) prior to contraction - it is related to ventricular filling.
What is Afterload?
Afterload is the force or load against which the heart has to contract to eject the blood during systole
