GEN SURG part 2 Flashcards
Norm Na levels in serum
135-145
Norm K levels in serum
3.5-5
Norm Ca levels in serum
2.2-2.6
Norm Cl levels in serum
94-111
Norm lactate levels in serum
1-2
Composition of 0.9% saline
OSM: 308
Na+ - 154
Cl- 154
Composition of 4% dextrose 0.18% saline
OSM: 283
Na 30
Cl 30
40g dextrose in 1 L h20
Composition of Hartmanns
OSM 278 Na 131 K 5 Ca 2+ 2 CL 111 Lactate 29
Composition of Gelatine 4%
OSM 290
Na 145
Cl 145
Composition of 5% albumin
OSM 300
Na 150
Cl- 150
Which solutions are ‘colloids’
Gelatin
Albumin
Why do colloids not work like they do in theory
ill pt have leaky vessels so are not as effective
Other -ves of colloids (2)
Expensive
Cause anaphylaxis/allergies
If you give a 70kg man 1L of pure water, how much ends up in the plasma
83ml
If you give isotonic solutions, what % ends up in the ECG
100%
If you give a 70kg man 1L of isotonic solution, how much ends up in plasma
250ml
E.g.s of ‘sensible’ losses
Urinary losses
E.g.s of insensible losses ‘3’
Sweat
Lungs
Faeces
E.g.s of ‘additional’ losses (4)
NG tubes
Stomas
Drains
3rd space losses
What is the ‘third space’
Cavities where fl does not normally collect and is not readily exchangable
Egs of third spaces (3)
GIT
Pleura
Peritoneum
How many ml lost via urine a day
c.1L
How many ml lost by lungs and faeces a day
c 500ml
How many ml lost by sweating a day
500ml
how many L of fl does an ill pt in hospital need /day
3L
1 salty 2 sweet regimen
1L norm saline +20mmol KCl over 8h
1L 5% dextrose w/ 20mmol KCl over 8h
1L 5% dextrose w/ 20mmol KCl over 8h
What must you ALWAYS do before prescribing fl
Chekc U+E
If pt has pyrexia, how does fl regime change
+ 10% for ever degree of fever
What activates the RAAS
Decreased effective aa blodo volume –> decreased renal blod flow
Or
By unloading of high pressure baroceptors in the aa system
Where are the baroceptors (3)
LA
Carotid body
Aortic arch
What deactivates the RAAS
Increaseed EABV –> stretch atrial myocardium –> release of ANP
ANP vasodilates renal aaa _ decreasees RAAS activity
sx of mild dehydration (3)
Headache
lack of E
Tired
sx of mod dehydration (4)
Dry mouth
Decr alertness
Sunken eyes
Mm cramps
Sx of severe dehydration (5)
Confusion Disorientation TachyC Tachypnoea Low BP
Blood results dehydration
Deranged U+E
Markedkly raised urea
metabolic change vomiting
Hypochloraemic, hypokalaemia metabolic alkalosis
Tx vomiting
0.9% saline
+ 20mmol KCl
What do pancreatic, small bowel, and bile fistulas contain
High bicarbonate levels
How much K levels seem with these fistulae and why
Elevated (due to acidosis desplaces K from cells)
But really total body K is depleted
Metabolic changes in acute diarrhoea
Hyperchloraemic metabolic acidosis
Hypokalaemia if profuse
Tx diarrhoea if oral rehydration not possible
0.9% saline
20mmol K
Fl Mx stable pt w/ closed head injury
⅔ of maintenance isotonic solutions
Metabolic changes ATN (6)
Hyperkalaemia Hyperphosphataemia Hypermagnesia Hyponatraemia Hypocalcaemia Metabolic acidosis
Essential Ix for dehydration
FBC U+E Lactate GLucose Urinalysis
What is SIADH
Non-physiological release of ADH
–> DECREASED water excretion + normal Na excretio –> dilutional hyponatraemai
causes if SIADH (broad categories)
6
Malignancy CNS disorders Chest disease Endocrine disease (hypothyroidism) Drugs Other
Malignancies –> SIADH (3)
Small cell lung
Pancreas
Prostate
CNS disorders –> SIADH (3)
Meningoencephalitis
Haemorrhage
Head injury
Chest conditions –> SIADH (3)
TB
Pneumonia
Abscess
Drugs –> SIADH (2)
Opiates
Psychotropics
Ix SIADH
Hyponatraemia
Norm Urea/creatinine
Incr urinary sodium hence incr specific gravity urine
Def diabetes insipidus
Passage of large vol of dilute urine b/c imp water resorption by kidneys collecting ducts
What causes diabetes insipidus
reduced ADH secretion from post pit
OR
impaired response of kidney
Consequence of diabetes insipidus
Hypernatraemia
Raised plasma osmolality
