Blood Pressure And The Kidney

Question 1

Red flags of SEPSIS

Answer 1

• V, P or U (if changed from normal) in AVPU (awake/ responds to verbal stimuli/ pain/ unresponsive)
• acute confusion
• purpuric / non-blanching/ cyanosis rash
• systolic blood pressure _<90mmHg (or drop >40)
• heart rate >130bpm
• respiratory rate _>25 /min
• needs O2 to keep SO2 _>92% (88 in COPD)
• not passed urine last 18h/ UO <0.5ml/kg/hr
• recent chemotherapy (last 6 weeks)

Question 2

How do TPR, BP and CO fit into a triangle?

Answer 2

BP on top

CO X TPR bottom

Question 3

How does SEPSIS lead to low BP?

Answer 3

Reduced systemic vascular resistance and vomiting causes reduced intravascular volume

Question 4

How does the body respond to low Bp?

Answer 4

Low Bp->:

Activation of carotid sinus baroreceptors -> increased sympathetic activity -> (decreased sino atrial node threshold -> increased Hr) + (constrict afferent arterioles -> increased systemic vascular resistance -> increased capillary refill time) + (increased contractility -> increased SV)

Renin released by kidneys -> RAAS

Question 5

What should capillary refill time be?

Answer 5

<2 secs

Question 6

How do the kidneys respond to low Bp?

Answer 6

First self-preservation afferent arterioles dilate -> increase GFR but sympathetic activation causes vasoconstriction AA to maintain systemic circulation overrides

Sympathetic stimulation/ decreased Rena, blood flow/ reduced NaCl detected at JGA (juxtaglomerular apparatus) -> renin release

Renin converts angiotensinogen (from liver) to angiotensin 1 which angiotensin converting enzyme (from lungs/ kidney) converted to angiotensin 2 -> increased sympathetic activity, arteriolar vasoconstriction, ADH, aldosterone from zona glomerulosa adrenal cortex (NA/ Cl reabsorption/ K excretion/ H2O retention) slide 31

Question 7

Once blood pressure has improved in sepsis what 2 problems could occur and why?

Answer 7

Pitting oedema and puffy eyes due to peripheral oedema bc peripheral capillaries have become leaky and there is increased ECF volume

Could then give diuretics

And could get hypertension bc normal Bp resets so think hypotension when normal, need higher BP to excrete same amount of Na -> microvascular damage (kidneys/ brain/ peripheries) -> macrovascular damage e.g. MI/ stroke/ atherosclerosis plaques