Cardiovascular Flashcards
Blood Pressure Equation
SV X HR X SVR = BP
SV= Stroke volume (blood in ventricle- PRELOAD) 60-120ml
HR= Heart rate (contractility, force and velocity of shortening and squeeze) 60-80bpm
SVR= Systemic vascular resistance (pressure during contraction- AFTERLOAD)
Cardiac Output Calculation
Stroke volume SV X Heart Rate HR
Frank-Starling Law
Stroke volume increases as ventricle volume increases
Increase of pressure = increase of cardiac output
Cardiac Output
The amount of blood ejected from the ventricles in one minuite
HR X SV = CO
4-6 L/min = normal for adult
Stroke Volume
Amount of blood ejected from ventricles each contraction
Systemic Vascular Resistance
Force of ventricle ejection against force of the arterial vessels
Normal values 900-1200 dyn/sec/cm5
Blood pressure control
Medulla Oblongata in brain stem
Cardiovascular centres:
Sympathetic increases HR and contractility
Parasympathetic decreases HR and contractility
Vasomotor centre- constriction control
Higher brain region- stress/anxiety
Blood pressure control- different receptors
Baroreceptors- detect pressure (stretch) in aortic arch/ R atrium
Chemoreceptors- monitor CO2/Po2 levels aortic arch
Higher Brain region in hypothalamus- fight/flight responses ie: stress or hot/cold
BP- RAAS system
Drop in BP
Reduced kidney perfusion
Kidneys secrete Renin
Renin in liver turns to Angiotensin 1
AG1 then converts into AG2 in lungs (where ACE is)
AG2 causes constriction to increase SVR and therefore CO= increase BP
AG2 also acts on adrenal cortex
Secretion of aldosterone
Reduced urine output and increases Na reabsorption
SEPSIS
Life threatening organ dysfunction caused by a disregulated host response
SIRS- systemic inflammatory response syndrome
SEPTIC SHOCK
Profound, circulatory, cellular and metabolic abnormalities
B- BLOOD CULTURE U-URINE OUTPUT0.5ML/KG F-FLUID RESUS 30ML/KG STAT A-ANTIBIOTICS (within 1 hr) L-LACTATE O-OXYGEN 15L NRB SA02 >94%
SEPSIS MANAGEMENT
- Fluid review
- Low Tidal volume (6ml/kg)
- Steroids
- Glucose control <10
Fluid Resus
Osmolarity= hydration status/concentration osmotic particles
normally 275-300mmols/L
Isotonic fluid- Hartmans - same as inside and outside cell
Sodium Chloride- risk of hyperchloremic acidosis as Cl- is alkaloid, body removes by producing HC03 = free H+ ions (acidotic)
H+ + HCO3- = H2CO3 = H2O+O2
Hypotonic Fluid pulls fluid into cells
Electrical Activity of Heart
Sino Atrial node (SA) highest intrinsic rate -main pacemaker and influenced by Para and sympathetic system (75bpm)
Atrioventricular node (AV)- bridge between SA node- allows atrial contraction (40-60bpm)
Left and right bundle branch- allows ventricular contraction (20-40bpm)
Bundle of HIS
ECG Interpretation
p wave= atrial depolarisation <3ssq’s
QRS complex- ventricles depolarisation <3ssq’s
T wave= repolarisation of ventricles
U wave= bundle of his repolarisation
PR interval= delay in AV Node <3ssq’s
QRS if >3ssq’s - ventricle problem
Prolonged QT = sudden death/OHA (amiodarone can cause)
Blood flow through the heart
Venacava brings blood to heart through right atrium through tricuspid valve into right ventricle out via pulmonary arteries to lungs Pulmonary veins bring blood back to heart from lungs into left atrium through mitral or bicuspid valve into left ventricle through aortic valve into aorta out to rest of body
Main Veins
Jugular Subclavian Pulmonary Superior Vena Cava Inferior Vena Cava Hepatic Portal Hepatic Renal Iliac
Main Arteries
Jugular Subclavian Pulmonary Aorta Mesenteric Renal Iliac
Resting Potential
Isoelectric line on ECG
Maintained by Na+ pumps
No electrical activity