Shock and Haemorrhage Flashcards
Define shock.
Failure of the circulation to deliver oxygenated blood to meet tissue requirements.
Define ischaemia.
A reduction in blood flow to tissues, depriving them of oxygen.
List the causes of cell death due to shock.
1 - Metabolic failure (inadequate energy production).
2 - Metabolic acidosis due to lactic acid production.
How is oxygen delivery measured?
By measuring the concentration of lactic acid in the blood.
What is the equation for oxygen delivery?
DO2 = CO * (Hb * SPO2 * 1.34) + (PaO2 * 0.2)
Where SPO2 is oxygen saturation.
*This is oxygen carried by haemoglobin + oxygen dissolved in the plasma.
What determines afterload?
TPR.
What are the 3 categories of causes of shock?
For each category, state whether the mechanism affects preload, inotropy or afterload.
1 - Hypovolemic (affects preload).
2 - Cardiogenic (affects inotropy).
3 - Distributive (affects afterload).
Give an example of a hypovolemic cause of shock.
Haemorrhage.
List 5 cardiogenic causes of shock.
1 - Heart failure.
2 - Acute coronary syndrome.
3 - Dysrhythmia.
4 - Valve defects.
5 - Cardiac tamponade.
List 4 distributive causes of shock.
1 - Sepsis.
2 - Thyrotoxicosis.
3 - Anaphylaxis.
4 - Neurogenic causes (loss of sympathetic tone).
Define acute coronary syndrome.
A set of signs and symptoms due to decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function
Define cardiac tamponade.
A syndrome caused by the accumulation of fluid in the pericardial space, resulting in reduced ventricular filling.
Give the equation for mean arterial blood pressure.
MAP = DP + 1/3 (SP-DP)
List 6 clinically observable changes of a person in shock.
1 - Pale skin.
2 - Clammy skin.
3 - Alert only to speech.
4 - Low urine output.
5 - High respiratory rate.
6 - Poor capillary refill (upon applying pressure to the skin).
Why do patients in shock have a high respiratory rate?
As a compensatory mechanism for metabolic acidosis.
