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
How do vasopressors work?
Almost all are alpha-1 agonists
Cause vasoconstriction which improves preload and afterload
What vasopressors are used in critical care?
Metaraminol
Noradrenaline
How are vasopressors given in critical care?
As a continuous infusion
Should not be given through a peripheral cannula due to risk of peripheral vasoconstriction (unless emergency)
How do inotropes work?
Increase contractility of heart
Tend to be beta-1 agonists
What are the benefits of arterial lines?
Allow a constant measure of BP without needing repetitive cuff measurements
More accurate BP readings in patients who have ‘shut down’
What are the benefits of cannulas?
Last longer than arterial lines as they are inserted using an aseptic technique so can be used for a longer time without/with less of an infection risk
Last 7-10 days compared to 3 days with arterial lines
Can be used in ‘peripherally shut down’ patients - those with no peripheral veins that can be used will normally still have a jugular, subclavian or femoral vein that can be used
More options for veins used - jugular, subclavian, femoral
Less leakage
Quicker dilution
What are the disadvantages of cannulas?
If they become infected the infection is more serious and carries higher consequences, and removing it has more risk of complications
Insertion can hit major structures such as thyroid, lungs, trachea
Not ideal for large volumes in short time
What are the complications of vasopressors?
May constrict circulation that you do not want to constrict;
Pulmonary arterial circulation constriction
Arteries to gut -> ischaemic gut
Necrosis from peripheral vasoconstriction
What can be done for a vasovagal patient, before administering fluid or drugs?
Lie the patient flat and hold their legs in the air, and re-check BP to see if it improves
Features of the circulation that can be measured in critical care are markers of what?
End organ perfusion
What are the main markers of end organ perfusion that can be measured in critical care?
Cerebral perfusion - patient becomes more aware, able to talk etc. with improvement
Kidney - urine production occurs with perfusion, aim for early urine output of 0.5ml/kg/hour
Blood lactate levels - marker of anaerobic metabolism indicating that cells aren’t getting sufficient oxygen, if lactate starts to fall with treatment then you are on the right track
What are airway issues in critical care usually due to?
Neurological impairment e.g. sepsis, intracranial haemorrhage, rather than a physical problem e.g. tumour, foreign body
When is intubation usually indicated in relation to a patient’s GCS score?
When GCS is 8 or lower, however this is a guideline, not a set rule
What can be done in critical care for the head/brain to prevent additional disability?
Sedation - slow metabolic rate
Cool people - affect blood flow and therefore pressures
Anti-epileptics
Induced thio-coma
What can be done in critical care for the gut to prevent additional disability?
Pro-kinetics
NG tube or feeding through central line
Referral to surgeon if removal is necessary
What can be done in critical care for the kidneys to prevent additional disability?
Dialysis - different from that given to a CKD patient, dialysis is constant
What can be done in critical care for the liver to prevent additional disability?
No effective extra-corporeal treatments
Supported generally by feeding and supporting circulation
If liver fails, transplantation is the only treatment option, if eligible
What patients are encompassed by level 0 of comprehensive critical care?
Patients whose needs can be met through a normal ward
What patients are encompassed by level 1 of comprehensive critical care?
Patients at risk of their condition deteriorating or higher levels of care whose needs can be met on advice and support from critical care team
(no organs failing)
What patients are encompassed by level 2 of comprehensive critical care?
Patients requiring more detailed observation or intervention
Those with single failing organ system or post-operative care, and higher levels of care
(e.g. septic shock or single organ failure)
What patients are encompassed by level 3 of comprehensive critical care?
Patients requiring advanced respiratory support alone or basic respiratory support together with support of at least two organ systems
This includes all complex patients requiring support for multi-organ failure
What levels of comprehensive critical care do high dependency and intensive care usually refer to?
High dependency refers to level 1 or 2
Intensive care usually means level 2 or 3
(i.e. single organ - HDU, multi-organ intensive care)
What is the cost per day of a patient staying in critical care?
£1500
What respiratory support is given in critical care?
Non-invasive ventilation
Invasive ventilation
Advanced respiratory support
What non-invasive ventilation options can be given in critical care?
CPAP
Assisted spontaneous ventilation - improves minute volume and increases CO2 clearance
What invasive ventilation options can be given in critical care?
Endotracheal tubes
What are the benefits of endotracheal tubes?
Allow use of higher pressures without leakage
Airway protection
Full ventilation overriding or not dependent on intrinsic effort
When is advanced respiratory support given? How is this given?
When conventional ventilation fails, addition of inhaled NO
Given via HFOV or ECMO
In what conditions might ventilatory support be indicated in critical care?
Severe pneumonia - hospital/community acquired Pulmonary embolism Congestive cardiac failure Life-threatening bronchospasm SIRS
When might airway protection be indicated in critical care?
Decreased conscious level
Actual or impending acute airway compromise
Sedation to allow treatment of a delirious patient’s underlying disorder
What cardiovascular support might be given in critical care?
Invasive monitoring with appropriate fluid resuscitation
Inotropic or vasoactive support
Intra-aortic balloon counter pulsation
Extracorporeal support e.g. ECMO, VAD
What renal support might be given in critical care?
Dialysis (rarely)
Continuous veno-venous haemofiltration (CVVHDF)
Slow continuous ultrafiltration (SCUF)
Sustained low-efficiency dialysis (SLED)
When might renal support be indicated in critical care?
Acute renal failure secondary to sepsis or other shock states
When might neurological support be indicated in critical care?
Trauma
Spontaneous intracranial haemorrhage
Status epilepticus
Meningitis
What neurological support can be given in critical care?
Monitoring of ICP
Treatment of raised ICP
Management of physiological parameters - PCO2, PO2, MAP, glucose, temperature
Osmotherapy, mannitol, hypertonic saline
Therapeutic hypothermia
Burst suppression of cerebral activity
When should patients go to ICU?
When:
There is reversible organ dysfunction or failure
Supportive treatment to allow definitive treatment to work
Patients who are beyond capabilities of other levels of care
When should patients not go to ICU?
Progressive decline in chronic irreversible condition
Those who will not survive
Those who will not become free from support available within the ICU
Likely outcome represents quality of life that would be unacceptable to the patient
What is involved in identification and early treatment in critical care?
Systematic management of ABC Appreciation of clinical urgency Seeking advice appropriately Proper use of monitoring Good organisational skills Adequate supervision by senior staff Background knowledge and understanding
