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Science to Clinical Practice
Terms in this set (22)
A 55 year old woman has a four day history of diarrhoea which is now blood stained. She has not passed urine for 12 hours.
Her temperature is 38.0ºC. Her pulse is 104 bpm, blood pressure 95/60 mmHg and capillary refill time 4 seconds. Her hands and feet are cold. She has reduced skin turgor. She has some tenderness in the left iliac fossa.
Hypotension, Tachycardia, Fever, Vasoconstriction, Dehydration, Oliguria (<0.5ml/kg/hr, usually <40mls/hr)
- Sodium 131 mmol/L (135-145)
- Potassium 5.0 mmol/L (3.5-5.0)
- Urea 24.0 mmol/L (3.0-7.0)
- Creatinine 180 µmol/L (60-110)
What is the diagnosis?
Acute Kidney Injury due to reduced glomerular perfusion.
What is the definition of acute kidney injury?
An abrupt decline in kidney function (usually <48 hours).
>30 µmol/L increase in creatinine
>1.5 x increase in serum creatinine
Urine output <0.5 mL/kg/hour for 6 hours
How does diarrhoea / fluid loss lead to AKI?
Low BP = sympathetic activation, +ADH secretion, RAAS activation.
Sympathetic activation = tachycardia + vasoconstriction.
Vasoconstriction = reduced renal blood flow = reduced GFR.
+ADH secretion = reduced renal blood flow = reduced GFR / +water resorption = oliguria.
RAAS activation = +ANGII / +aldosterone = +Na resorption.
How does angiotensin II maintain glomerular perfusion in AKI?
Causes greater constriction of the efferent arteriole, increasing intraglomerular pressure, maintaining perfusion.
What is the treatment of AKI?
Patient will have a deficit of 5-10 L + daily requirement
Start with either 0.9% sodium chloride (154 mmol/L sodium, 154 mmol/L chloride, slightly hypertonic) or plasmalyte
What are the normal daily requirements of fluid?
Normal daily requirements are 30 mL/kg/day
How do you know if you are giving the patient enough fluid?
Weight of the patient - weigh when come in, then for each litre of fluid gain should be +1kg.
Why is a very high potassium worrying?
Can lead to cardiac arrest.
How can taking an ACEi with vomiting/diarrhoea lead to hyperkalaemia and hypotension?
Fluid loss through vomiting/diarrhoea.
However ANGII is not produced = glomerular afferent arteriole dilatation = reduced GFR = reduced K+ excretion = hyperkalaemia.
Also, aldosterone is not produced = reduced K+ secretion = hyperkalaemia / reduced sodium resorption = reduced salt and water retention.
(aldosterone resorbs sodium in exchange for potassium)
What would the treatment be for a hypotensive and hyperkalaemic patient due to ACEi and fluid loss?
Treat underlying hypovolaemia
Intravenous calcium salts: "stabilises" the myocardium (works for about 20-30mins)
Reduce serum potassium
- Insulin/glucose infusion
- Insulin stimulated glucose uptake leads to potassium shift into cells (have only MOVED the K, so if there is an underlying problem it won't fix it - works for about 4-5 hours)
A 74 year old man is admitted with increasing confusion. He has a one year history of urinary hesitancy, urgency and incontinence.
His pulse is 80 bpm and blood pressure 144/90 mmHg. He has a palpable suprapubic mass.
Sodium 140 mmol/L (135-145)
Potassium 5.2 mmol/L (3.5-5.0)
Urea 20.0 mmol/L (3.0-7.0)
Creatinine 355 µmol/L (60-110)
What is the diagnosis?
Urinary outflow blockage due to benign prostatic hypertrophy.
What are the medicine sick-day rules? Which drugs do they apply to?
If unwell with vomiting/diarrhoea or fever/sweats/shaking then stop taking medicines until 24hrs of eating/drinking normally.
What is hydronephrosis?
Urinary outflow blockage causes pressure build up in urinary pelvis and it expands: lose glomeruli and replace with scarring and fibrosis.
What are the lower urinary tract symptoms (LUTS)?
Urgency, Frequency, Nocturia, Incontinence, Hesitancy, Poor stream, Terminal dribbling
What are the stages of bladder filling and emptying?
1. peristaltic wave travels down ureter (1-5 times per min)
2. ureteric opening opens
3. bladder wall is stretched upon filling
- first urge to void 150ml
- sense of fullness 400ml
- discomfort 600ml
4. internal urethral sphincter (smooth muscle/involuntary)
5. external urethral sphincter (skeletal muscle/voluntary)
Describe the receptor types in the bladder
- bladder neck
- pelvic floor
Detrusor: muscarinic (M2 = 80%, M3 = 20%) beta-3 adrenergic.
Mucosa/submucosa: M2, M3
Bladder neck: alpha-1 and alpha-2 adrenergic
Pelvic floor: nicotinic (voluntary)
Urethra: alpha-1 and alpha-2 adrenergic
What is the treatment for benign prostatic hypertrophy leading to hydronephrosis and LUTS?
Insert a urinary catheter: Allow decompression of renal tract
Start an alpha-blocker: Trial without catheter (TWOC)
May need transurethral prostatic resection (TURP) surgery
What are the two types of female incontinence and the treatments?
Stress incontinence: Involuntary leakage when intra-abdominal pressure raised
Treatment: pelvic floor exercises
Urgency incontinence: Urge to void followed by involuntary leakage
What is nephrotic syndrome?
Hypoalbuminaemia (low serum albumin)
A 20 year old woman has a four week history of ankle and facial swelling.
Her blood pressure is 108/68 mmHg. She has pitting oedema to her knees. Her urinalysis has protein 4+.
Urea 4.5 mmol/L (3.0-7.0)
Creatinine 65 µmol/L (60-110)
Albumin 20 g/L (35-48)
What is the diagnosis?
(Nephrotic Syndrome - NOT a diagnosis)
This is probably a disease called minimal change disease: circulating proteins cause loss of podocyte connections. Albumin therefore leaks out into filtrate - measured on dipstick.
What is the underfill hypothesis?
Mechanism of oedema.
Albumin lost in urine.
Decreased serum oncotic pressure.
Fluid moves from blood to extracellular space = oedema.
Salt and water retention = oedema.
++Na/K ATPase activity in CD, ++Na epithelial channel, resistance to ANP
Stimulates renal sodium and water retention.
What is the treatment for pitting oedema?
Diuretics: Increase renal salt and water loss
- Loop diuretics such a furosemide most commonly used
Treat underlying diseases
- Prednisolone (steroids) will treat most cases
This set is often in folders with...
Filtration - Anatomy + Function of the Glomerulus
Lower Urinary Tract
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