Critical Care Flashcards
What are the normal Na+ requirements?
1-2mmol/kg/day
What are the normal K+ requirements?
0.5-1mmol/kg/day
What are the normal fluid requirements?
25-30ml/kg/day
What are the normal glucose requirements?
50-100g/day
What are the main things managed in critical care?
Airway Breathing Blood gases Circulation Disability
Why is respiratory rate a good marker in critical care?
Respiratory rate is the most sensitive marker of an unwell patient, while it won’t tell you what is wrong with the patient it is a good indicator of decline as it is likely to be one of the first things to decline when a patient is unwell/worsening
How much oxygen can critical care doctors provide, compared with a normal ward?
Most wards can give 15 L/min maximum
Critical care can give up to 70 L/min, can use non-invasive ventilation and invasive ventilation
Why might breathing machinery be useful in critical care?
Extremely unwell patients may be too weak to sustain breathing themselves, machinery can take over the work of breathing
What can be done for patients with inadequate ability to sustain gas exchange or perfusion?
ECMO - Extra-Corporeal Membrane Oxygenation
Why are blood gases used regularly on critical care wards?
All patients will have an arterial line in so it is easy to obtain blood gas readings
What are the main blood gas readings done in critical care?
pH
CO2
PO2
Why is there a limited amount of improvement you can make for a patient by increasing their heart rate?
Drugs can be given to increase heart rate but at a certain point the increase will no longer have any beneficial effect on cardiac output (CO = HR x SV) and may even worsen CO
How is stroke volume determined?
SV is hard to determine
Subdivided into preload, contractility and afterload
Preload, contractility and afterload cannot be directly measured by markers of them can be measures
What should fluid challenge be used as?
Intervention, not therapy
How does fluid challenge work?
A volume of fluid is given as quickly as possible to a patient with hypotension and tachycardia, BP and heart rate are monitored
If BP goes up and HR goes down then this tells you that the patient is hypovolaemic (decreased volume of blood plasma) and so requires more fluid
According to sepsis 6, when should you stop giving fluid and try a new approach? Why is this?
When fluid reaches 30ml/kg and there is no improvement
Run the risk of fluid overloading the patient
What pressure do organ systems require to work?
Perfusing pressure
What MAP value will sustain pressure autoregulation?
50-150mmHg
What does MAP reflect?
Average pressure across the cardiac cycle
What MAP value is aimed for in intensive care?
65mmHg
What is the difference between crystalloid and colloid fluids?
Fluids are broken down by the size of molecules in them
If small molecules - crystalloid
If large molecules - colloid
What are the crystalloid fluids used in critical care?
0.9% saline
5% dextrose
Hartmann solution
What crystalloid fluid should not be used as a resuscitation fluid?
5% dextrose
What are the colloid fluids used in critical care?
Blood most common
Albumin
(colloid starches and jelly products taken off market due to renal failure)
What is the benefit of using albumin?
Doesn’t need any cross-matching/immuno-compatibility