Flashcards in The Unwell Patient Deck (27)
What are the reasons for giving someone fluids?
To maintain euvolaemia when oral intake is reduced
To replace previous fluid losses
To replace on going fluid losses
To replace fluid losses which are about to occur
What are the electrolyte content of different body fluids?
Compared to serum:
Sweat = low Na and low Cl
Gastric juice = high K Cl and H
Bile = high Na, K, HC3 and Cl
Diarrhoea = variable, like bile
What are the clinical signs when you loose 5% and 10% of your body weight?
Dry mucous membranes, mild postural drop, normal or high HR, normal BP
very dry mucous membrane, >20mmHg postural drop, high HR, normal or low BP
Other symptoms include:
dizziness and confusion, thirst, weight loss, poor urine output
What is the insensible loss of a normal well adult?
700mls - 1L
Sweat, GI loss and exhaled water
Does not include urine as it is measurable
If you give a patient 1L of 10% dextrose, how much is left in the plasma after re distribution?
60mls - only 6% of the bodies water is plasma.
60% is intracellular fluid
34% is interstitial fluid
Describe the difference between the different fluids and plasma:
Higher Na and Cl
No K, Ca, HCO3
Similar to plasma
Slightly lower Na, and Ca
Slightly higher Cl, K, HCO3
When should you use 0.9% saline?
To replace upper GI losses (duodenal fistulas)
DKA initially when BM >15
What are the problems with using 0.9% saline?
Hypernatraemia - if used as the only maintenance 5x daily Na
When should you use Hartmann's?
For maintenance, resuscitation and to replace large stoma losses
How man calories does 1L of 5% glucose have?
What the is max concentration of K you can give peripherally?
20mmol in 500mL
Max rate is 10-20mmol per hr
When is the use of Human Albumin solution indicated?
Very large protein rich ascitic losses (500mls of Albumin 4.5% for every 2-3L drained)
Management of burns losses
Fluid resuscitation - 20% in hypernatraemia
How is the oxygen content of blood calculated?
What causes it to fall?
Sats x Hb x 1.34
Hb falls - haemorrhage, and haemodilution post fluids
Saturation fall - capillary leak of fluid into the alveoli, impaired CO causing pulmonary oedema, and underlying cardio resp trigger
Describe the Frank Starling mechanism.
Increasing the venous return to the left ventricle increases left ventricular end diastolic pressure and volume, thereby increasing ventricular preload. This results in an increase of stroke volume.
Basically, an increase in right atrial pressure causes an increase in stroke volume
How many molecules of ATP are make per molecule of glucose in aerobic respiration?
36, compared with 2 in anaerobic
What is the definition of SIRS?
Two or more of:
RR >20 or pCO2 11 or 38 or
What is the difference between sepsis and septic shock?
Septic shock is severe sepsis with hypotension
How are organs affected by sepsis?
Kidneys - reduced urine output
Brain - confusion
GI - ileus, bacterial translocation, stress ulcers, ischemia
Liver - poor synthetic function
Haematological - coagulopathy
How do you calculate oxygen delivery>
CO x Hb x SaO2 %
so to treat low O2 delivery you can improve CO, raise Hb if low and maximise O2 saturations
What is cardiac output?
CO = Heart rate x stroke volume
stroke volume is determined by preload, contractility and afterload
What causes a reduce preload?
Absolute - loss of blood or plasma volume
Relative = vasodilatation
What causes reduced contractility?
Mi, myocardial ischemia, sepsis, drug overdose
Other than tachycardis what are some other signs that a patient has low CO?
long cap refill
What is the normal intra abdominal pressure?
What is the definition of intra abdominal hypertension?
5 - 7mmHg
It increases with high BMI and pregnancy
Intra abdominal hypertension > 12mmHg
What is abdominal compartment syndrome?
When there is a sustained intra abdominal pressure of > 20 plus new organ dysfunction.
Can be causes by pancreatitis and GI surgery, or sepsis, burns, and fluid resus
abdominal perfusion pressure = MAP - IAP
Pts have abdominal distension ad pain, hypotension increases HR, tachypnoea, hypoxia, low urine output, cool skin. They are obtunded or restless and have a lactic acidosis
What is cerebral perfusion pressure?
How is it affected by changes in ICP and MAP?
CCP = MAP -(ICP + CVP)
if ICP rises then MAP must rise to maintain the same cerebral blood flow.
If MAP falls then cerebral blood flow with fall
If ICP rises and MAP falls then CCP will drop +++ and neurological injury will occur.