Critical care medicine

Question 1

Reasons for admission

Answer 1

• Respiratory support
• Invasive monitoring e.g. pressure, cardiac function
• Renal support
• Decreased conscious level

Question 2

What are we trying to achieve

Answer 2

• The maintenance of oxygen perfusion to vital organs
• Removing or treating the causes of the problem
• Treating other problems that are produced
• allowing the body to recover

Question 3

How do we do this

Answer 3

• Airways/Breathing
• Circulation
• Sedation and analgesia
• Sepsis

Question 4

Cardiac output

Answer 4

Question 5

How do we measure cardiac function

Answer 5

• Indirect measures
  
  • BP: Central venous, arterial
  • For the left side of the heart
    
    • LiDCO
    • PiCCO
    • Oesophageal Doppler
    • Swan Ganz/ Pulmonary artery flotation catheters

Question 6

Circulatory failure

Answer 6

• Inadequate pre-load
• Maldistribution
  
  • Anaphylaxis
  • Septic shock
• Myocardial failure
  
  • Systolic +/- diastolic dysfunction

Question 7

Inadequate pre-load

Answer 7

• Measurements
  
  • Central Venous Pressure (CVP)
• Treatment: Give fluid
• Choice
  
  • Crystalloid
  • Colloid

Question 8

Maldistribution

Answer 8

• Measurement- low systemic vascular resistance (SVR)
• Also known as ‘afterload’ (for the left side of the heart)
• Treatment: Give a vasoconstrictor (Vasopressor)

Question 9

Receptor types

Answer 9

• Alpha 1 + 2- vasoconstriction of blood vessels
• Beta 1- Inotropic
• Beta 2
  
  • Vasodilation of blood vessels
  • Bronchodilator

Question 10

Noradrenaline

Answer 10

• Acts on a1 and b1 (i.e. primarily heart of vascular smooth muscle)
• Results in increased SVR and increased heart rate
• Adverse effects
  
  • Mainly related to decreased organ perfusion leading to ischaemia (e.g. splanchnic bed, digits)

Question 11

Dopeamine (DA)

Answer 11

• Low dose- D1-dopaminergic receptors in vascular tissue esp. Renal, mesenteric and coronary beds- leads to vasodilation
• High dose- b1-receptors (i.e. heart)
• Also causes the release of noradrenaline which results in vasoconstriction
• Adverse effects
  
  • Tachycardia
  • Arrhythmias
  • Myocardial ischaemia

Question 12

Vasopressin

Answer 12

• Acts on V1 receptors
• Causes profound vasoconstriction

Question 13

Myocardial failure

Answer 13

• Measurement: low cardiac output
• Treatment: Give an inotrope
• Choice

Question 14

Inotrope

Answer 14

• Ino = fibre
• trepein - to turn or influence
• Literally- to turn or affect muscle fibres
• Can be positive or negative

Question 15

Dobutamine

Answer 15

• B1- agonist (-&+) isomers
• a1- agonist0 (-) isomer
• a1- antagonist - (+) isomer
• B2- agonist
• Net result- Increase contractility, with some effect on rate
• Adverse effects
  
  • Tachycardia & arrhythmias
  • Can lead to increased myocardial oxygen consumpton, and hence ischaemia
  • Can get tolerance

Question 16

Adrenaline

Answer 16

• b1- agonist
• a1-agonist
• b2- agonist
• Net result: Increased contractility and HR
• Adverse effects
  
  • Myocardial ischaemia
  • Tachycardia
  • Arrhythmias
  • Sudden death

Question 17

Phosphodiesterase inhibitors

Answer 17

• Act to increase cAMP levels in cardiac and smooth muscle
• Results in
  
  • Myocardial diastolic relaxation
  • Increased intracellular calcium levels
  • Dilation of vasculature
  • Relaxation of bronchial smooth muscle
  • Dysrhythmias

Question 18

Phosphodiesterase inhibitors

Answer 18

• Enoximone and milrinone available
• Not user friendly
  
  • Long half-life
  • IV compatibility problems
• In oral form, associated with increased mortality

Question 19

Vasodilators

Answer 19

• Aim to decrease afterload, enabling the heart to beat more efficiently
• Examples
  
  • GTN or ISDN
  • Furosemide

Question 20

Levosimendan

Answer 20

• Calcium sensitiser
• Increases contractility of cardiac myofibrils
• Unlicensed in this country
• Recent study showed no benefit

Question 21

Analgesia

Answer 21

• Opioids
  
  • Infusion
  • Care with renal/hepatic impairment
• Paracetamol

Question 22

Sedation

Answer 22

• BZ
  
  • By infusion
  • Care with renal/hepatic impairment
• Propofol
  
  • Intravenous anaesthetic agent
• Antipsychotic agents
  
  • For delirium

Question 23

Paralysing agents

Answer 23

• Limited use
  
  • Difficulty in ventilation
  • Neuro-injury
• Must have adequate analgesia and sedation on board
• Non-depolarising agents used

Question 24

Clonidine

Answer 24

• Adrenergic agonist
  
  • Activates central inhibitory a2-receptors
  • Depressive effect on CNS function
• Opioid sparring
• Useful in withdrawal states
• Dexmedetomidine

Question 25

Continuous veno-veno haemofiltration

Answer 25

* Removal of solutes by convection * Independent of MW * Modern membrane pore sizes 10,000-30,000 daltons * active process

Question 26

Haemofiltration

Answer 26

Question 27

Sepsis

Answer 27

* 2016 definition- Life-threatening organ dysfunction caused by the dysregulated host response to infection * Sepsis is one of the 'golden hour' emergencies

Question 28

Consider sepsis if

Answer 28

* RR \>22/min * Altered mental state * Systolic BP \<100 mmHg

Question 29

Septic shock

Answer 29

* Sepsis + * Vasopressor therapy needed to maintain MAP \>65mmHg * Lactate \>2mmol/L * Despite adequate fluid resuscitation

Question 30

Sepsis- why is it important

Answer 30

* Estimated 37,000 deaths/year in the UK * Further 65,000 survive (but many with long term sequelae) * NCEPOD 2015 report 'just say sepsis' * Kills more than breast, bowel and prostate cancer combined

Question 31

NICE guideline- NG51

Answer 31

* Sepsis: Recognition, diagnosis and early mangement * Think: Could this be sepsis for any patient presenting with an infection

Question 32

What happens after critical care

Answer 32

* Rehabilitation * Long term follow up * Support groups * ICU steps

Question 33

Post-discharge/rehabilitation

Answer 33

* Physical state worse than pre-admission * May take months/years to improve * Scarring * Mental state * Delirium * Hallucinations * Anxiety