5 - shock & ECG Flashcards
(25 cards)
what is shock?
any condition when the blood vessel are not filled and blood cannot circulate normally.
what are the 5 different types of shock?
- hypovolemic shock
- vascular shock
- cardiogenic shock
- obstructive shock
- transient vascular shock
what causes hypovolemic shock?
rapid drop in blood volume caused by:
- severe vomiting a diarrhoea
- a large scale loss of blood
- severe dehydration
what happens to the body during hypovolemic shock?
- intense vasoconstriction: blood is moved from reservoirs to maintain circulation to enhance venous return
- BP stabilises: if loss continues drop in BP means hypovolemic shock
- needs to replace fluid volume ASAP
what causes vascular shock?
normal blood volume but poor circulation due to extreme vasodilation resulting in a falling BP
what other shocks can vascular shock result in?
- anaphylactic shock (allergen)
- neurogenic shock (sympathetic nerves)
- septic shock (bacterial toxins)
what causes cardiogenic shock?
occurs when the heart is so inefficient, usually due to an MI, it cannot sustain circulation
what causes obstructive shock?
obstruction to blood flow, most common is pulmonary embolism
what causes transient vascular shock?
occurs after sunbathing for too long, blood vessels dilate in the lower limbs
when standing you get pooling of blood in the lower body, drop in BP and giddiness
what are the symptoms of shock?
- hypotension - systolic below 90mmHg
- pale skin, moist clammy hands due to vasoconstriction
- confusion and disorientation (due to hypotension, decreased blood flow to heart
- increased heart rate due to sympathetic stimulation
- decreased urine due to hypotension
- thirst
- decreased blood pH (acidosis)
what are the 3 stages of shock?
compensated shock - stage I
progressive shock - stage II
irreversible shock - stage III
what happens during compensated stage (stage I)
- homeostatic adjustments cope with shock
- vasoconstriction and mobilisation of blood
reserves to increase blood volume and blood
pressure - long term hormonal release of ADH, renin angiotensin aldosterone system & EPO
what happens during progressive stage (stage II)
decline in systemic blood pressure, tissue blood flow and cardiac output
what happens during irreversible stage (stage III)
rapid decline in cardiac output, irreversible fall in BP, circulatory collapse and death
what does an ECG do?
records 12 different views (using 10 electrodes) of the heart and provides a complete “picture” of electrical activity
what heart rate is considered to be bradycardia and tachycardia?
bradycardia is <60bpm
tachycardia is >100bpm
what causes atrial flutter?
impulses circulate in a localised loop, causing atria to contract at a rapid rate (150-300)bpm
what causes atrial fibrillation?
- unsynchronised impulses from multiple ectopic foci in the atria
- atria fibrillate (quiver) and don’t contract properly
what causes ventricular tachycardia?
- impulses from an ectopic site in the ventricles promote rapid premature ventricular contractions (>100)
what causes ventricular fibrillation?
unsynchronised impulses from multiple ectopic foci in ventricles
- ventricles will fibrillate and don’t contract properly
what causes premature ventricular contractions?
- one or more ectopic sites in the ventricles generate an electrical impulse that triggers a premature ventricular contraction
what causes conduction disorders?
- caused by alterations in the cardiac conduction pathways
- compression by scar tissue or calcified portions of the heart
- inflammation can depress conductivity from atria to ventricles
- extreme stimulation of the heart by the vagus nerves block impulse conduction
what is a first degree block in conduction disorders?
electrical impulses transmission is slowed down between atria and ventricles
what is a second degree block in conduction disorders?
atrial depolarisation will sometimes not be strong enough to elicit ventricular depolarisation
