107 - Hypovolemia Flashcards
Definition of shock
Failure of CVS to adequately perfuse tissues. Critically low oxygen delivery to mitochondria. 4 types.
Define hypovolaemia
Loss of ~20% of blood volume. Caused by sharp decline in cardiac output due to empty circulation.
Cardiogenic shock
Caused by failure of heart to pump correctly.
Maldistributive shock
Caused by abnormal dilation of the small arteries. Commonly due to infection (septic shock) or allergy (anaphylactic shock).
Obstructive shock
Physical blockage to heart or major vessels that reduces cardiac output. Mainly due to pulmonary embolism.
Recognising Shock
Present with features of organ failure and sympathetic activation (fight or flight). Collapse Changes to consciousness Tachypnoea Tachycardia Hypotension Poor peripheral perfusion Low urine output Raised blood
Characteristic features of hypovolemia
Evidence of blood loss
Dry, empty circulation
Characteristic features of cariogenic shock
Chest pain
EGC and rhythm changes
Rising upstream pressure
Pulmonary and peripheral oedema
Characteristic features of maldistributive shock
Source of sepsis - signs of infection.
Warm, dilated circulation unless severe.
Characteristic features of obstructive shock
Same as cardiogenic but without signs of MI etc.
Poss DVT, thoracic injury
0-15% blood loss - impact on patient.
Thirsty
15-30% blood loss - impact on patient.
Tachycardia
30-40% blood loss - impact on patient.
Hypotension
> 40% blood loss - impact on patient.
Game over
How to remember the impact on patient based on blood loss
Tennis score rules
When should fluid resuscitation be done in patients with shock
ASAP. Caution in older patients as can affect heart.
What are U&Es
Basic blood test for kidney function. Looks at levels of urea, Na and K. Creatinine levels also usually measured
Urea - acts as marker of what
Produced when body trying to rid itself of proteins. Useful as marker of dehydration or exposure to large amount of protein. Released by kidneys so marker of how efficiently kidneys are working.
Sodium and Potassium - role in blood
Involved in reabsorption of kidney, determining resting membrane potential and creating action potentials.
Low levels of urea can indicate
Liver failure. Can also result in raised ammonia which can cause confusion/coma.