Revision Group Work Flashcards
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
a) What are the signs and symptoms of hypovolaemia?
- Low blood pressure
- Low urine output
- High heart rate (tachycardia) that manifests as a thready pulse
- Dizziness
- Pale skin
- Confusion
- Clammy (cold)
- Reduced turgor (skin doesn’t come flat when pulling it up)
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
b) From which body fluid compartment is the fluid [blood] lost?
Extracellular
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
c) What is the normal osmolality of blood and how will it alter immediately after the haemorrhage?
Normal is 280 - 300 mOsm/kg
Immediately after the haemorrhage it won’t change bc it will take time to balance, but over time the osmolality will go down.
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
d) Infusion of which of the following solutions would benefit the patient more: an infusion of (a) 5% dextrose (D5W) or (b) 0.9% (0.15 molar) saline?
Saline because we want it in the extracellular compartment
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
e) How many litres of each solution would you need to replace one litre of blood loss? How would each solution affect osmolality and serum sodium concentration in each compartment?
1:1 ratio so replace how much is lost. (Technical answer is 5.56 L due to slide 9 on Alex Pike’s revision lecture) In reality just keep monitoring after each bag and see whether his BP is picked up - this bolus is done over 15 mins.
Dextrose would increase osmolality in every compartment, whereas saline wouldn’t affect osmolality.
Dextrose would not affect the serum sodium concentration, and neither would saline because saline is isotonic.
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
f) What compensatory mechanisms will be initiated in the patient due to his hypovolaemia?
Baroreceptor reflex, activated first due to the drop in blood pressure. Then RAAS will be activated long term, and then the ADH response.
Case 1
A 65 year old man collapsed after vomiting copious amounts of fresh blood. When seen in ED he was confused, with a pale, clammy skin. He was a chronic heavy drinker. Physical examination revealed a weak, rapid but regular pulse (120 beats/minute). His supine blood pressure was 100/75 mmHg and fell to 80/65 mmHg when sitting with his legs dangling over the side of the bed. He has bleeding oesophageal varices due to portal vein hypertension (alcoholic cirrhosis of the liver). While waiting for blood to be cross-matched, he received an intravenous fluid infusion. An initial blood test showed both his haematocrit (packed cell volume fraction) and haemoglobin to be low. His urine output was low (20 ml/hour).
g) What important physiological process would account for the finding that the haematocrit and haemoglobin concentrations were low on admission? Hint: Consider capillary forces and a hormonal response.
Bleeding out blood - lose physical blood cell so they lose haemoglobin and haematocrit - so they have the same amount of fluid but they don’t have the same amount of content in them.
The hormonal response is EPO made by the kidney to increase the amount of red blood cells made in the bone marrow.
Case 2
A man weighing 60kg (132lbs) has severe diarrhoea and vomiting (D&V) during a GI infection. During this period he loses 4kg (9lbs) in body weight. His plasma Na+ concentration is unchanged by the events.
a) Complete the table below by calculating the volumes before and after D&V.
Before D and V (L)
Total body water -
ICF volume -
ECF volume -
After D and V (L)
Total body water -
ICF volume -
ECF volume -
Before D and V
Total body water - 36 L
ICF volume - 24 L (23.99999)
ECF volume - 12 L
After D and V
Total body water - 33.6 L
ICF volume - 22 L
ECF volume - 11.6 L
Case 2
A man weighing 60kg (132lbs) has severe diarrhoea and vomiting (D&V) during a GI infection. During this period he loses 4kg (9lbs) in body weight. His plasma Na+ concentration is unchanged by the events.
b) In such a condition where plasma [Na+] is unchanged, how and why would the following parameters change?
Plasma osmolality ECV Plasma ADH levels Urine Osmolality Sensation of Thirst
Plasma osmolality - osmolality will increase because you’re retaining ions but losing water after D&V
ECV - reduced, loss of water
Plasma ADH levels - increase to compensate bc osmolality is decreased
Urine Osmolality - increased bc dehydration, so you don’t want to lose more water in urine so you have stronger urine
Sensation of Thirst - increased to replace the fluid lost
Case 3
A triathlon competitor had been training in the Grand Canyon on a hot day. He has taken plenty of water before developing nausea, vomiting, agitation, confusion and a grand mal seizure.
His plasma sodium was <130mmol/L.
a) How might this hyponatraemia have developed?
Loss of salt through sweat, and he is drinking lots of water so he has an increased blood volume.
Case 3
A triathlon competitor had been training in the Grand Canyon on a hot day. He has taken plenty of water before developing nausea, vomiting, agitation, confusion and a grand mal seizure.
His plasma sodium was <130mmol/L.
b) How could he have avoided developing hyponatraemia?
The patient could have had isotonic drinks
Case 4
A 20 year old man fell off his motorbike and fractured his skull. A few days later, he experienced a severe thirst, frequent urination and a dry mucous membrane. Plasma sodium was elevated, plasma osmolality was higher than urine osmolality. Urine output remained elevated (150ml/hour).
Investigations show: Blood Chemistry Value Patient Value Normal Range Sodium 156 mmol/L 133 – 146 Serum osmolality 308 mOsm/kg 275–295 Urine osmolality 152 mOsm/kg (50 – 1200)
a) Look at the electrolyte and osmolality chemistry. What conclusions do you draw about this patients water balance and why?
Damage to posterior pituitary reducing secretion of ADH
Case 4
A 20 year old man fell off his motorbike and fractured his skull. A few days later, he experienced a severe thirst, frequent urination and a dry mucous membrane. Plasma sodium was elevated, plasma osmolality was higher than urine osmolality. Urine output remained elevated (150ml/hour).
Investigations show: Blood Chemistry Value Patient Value Normal Range Sodium 156 mmol/L 133 – 146 Serum osmolality 308 mOsm/kg 275–295 Urine osmolality 152 mOsm/kg (50 – 1200)
b) Speculate on the possible causes of polyuria and polydipsia in this patient.
OVLT
Case 5
A 49-year-old woman sees her doctor because of weakness, easy fatigability and loss of appetite, except for salted crisps. During the past month she has lost 7 kg (15 lb) in weight.
On physical examination: she has hyperpigmentation, especially of the oral mucosal, gums and skin creases of the MCP joints. She is hypotensive and her blood pressure (BP) falls when she assumes an upright posture (BP = 100/60 mm Hg supine and 80/50 mmHg upright).
The following laboratory data are obtained:
Serum [Na+] 130 mmol/L (135 to 147)
Serum [K+] 6.5 mmol/L (3.5 to 5)
Serum [HCO3-] 20 mmol/L (22 to 28)
a) What electrolytic imbalances are present?
Hyponatraemia, hyperkalaemia, reduced bicarbonate
Case 5
A 49-year-old woman sees her doctor because of weakness, easy fatigability and loss of appetite, except for salted crisps. During the past month she has lost 7 kg (15 lb) in weight.
On physical examination: she has hyperpigmentation, especially of the oral mucosal, gums and skin creases of the MCP joints. She is hypotensive and her blood pressure (BP) falls when she assumes an upright posture (BP = 100/60 mm Hg supine and 80/50 mmHg upright).
The following laboratory data are obtained:
Serum [Na+] 130 mmol/L (135 to 147)
Serum [K+] 6.5 mmol/L (3.5 to 5)
Serum [HCO3-] 20 mmol/L (22 to 28)
b) The serum level of which hormone(s) would be expected to be below normal in this woman? Which organ could be the principle cause of these electrolytic imbalances? Explain your reasoning in full.
Hormone:
Organ:
Reason:
Hormone: Cortisol
Organ: Adrenal gland
Reason: Cortisol binds to cortisol receptor on basolateral receptor, causing sodium resorption. If you don’t have this receptor leads to less fluid reuptake as it activates the aldosterone receptors on the kidney.
