Best Practice Flashcards
net positive fluid balance manifests as
interstitial oedema
triad for intra-vascular fluid depletion
tachycardia, drop in blood pressure, a postural fall in blood pressure.
NICE signs for hypovolaemia and urgent fluid resus
Systolic blood pressure below 100 mmHg
Heart rate above 90 beats per minute
Capillary refill time is longer than 2 seconds, or peripheries are cold to the touch
Respiratory rate is above 20 breaths per minute
National Early Warning Score (NEWS) is 5 or more
Passive leg raising suggests fluid responsiveness.
signs of fluid overload
elevated JVP, third heart sound, bibasal crepitations, dependent oedema, hypertension
volume responsiveness refers too
giving additional fluid will increase preload and cause a significant increase in stroke volume. This augments cardiac output and therefore perfusion and oxygen delivery.
limitations of fluid balance charts
don’t take account of insensible loss, oral water inaccurately recorded or urinal volume incompletely measured.
biochemical signs of dehydration or cardiac failure
urea is usually disproportionately raised when compared to creatinine.
reduced renal perfusion affects urine by
reducing volume of concentrated urine with low sodium excretion
An IVC collapse of below 12mm in a spontaneously breathing patient indicates
hypovolaemia
signs of preload responsiveness
sub aortic peak velocities, aortic blood flow, pulse contour analysis, respiratory variations of the IVC and SVC, passive leg raising.
NICE suggests the use of what for routine maintenance alone?
dextrose saline (0.18% sodium chloride with 4% glucose) with 27 mmol/l potassium added.
hypotensive urgent fluid resus NICE recommends
administer 500 ml of a crystalloid with a sodium content of 130 mmol/l to 154 mmol/l over less than 15 minutes.
what percentage of crystalloids end up in the interstitium
80%
hypovolaemic haemorrhagic shock NICE recommends
blood products
recovery from acute tubular necrosis is characterised by a
polyuric phase of several litres of diluted urine each day.
What urinary biochemistry would suggest persistent hypovolaemia rather than established acute renal failure?
1) Urine sodium 5 mmol/l
2) Urine osmolality 320 mmol/l
3) Urine specific gravity below 1010
4) Urine urea 84 mmol/l
1)Urine sodium 5 mmol/l
A patient presents with nephrotic syndrome:
Oedema
Proteinuria 5 g/24 hr
Reduced serum albumin.
Which one of the following would be an appropriate part of your management plan?
1) Saline infusion to replace intravascular depletion
2) 20% albumin infusion to correct hypoalbuminaemia
3) Low sodium diet
4) High protein intake
3) low sodium diet
if pH is below 7.35 and PCO2 is increased then there is
primary respiratory acidosis
if pH is below 7.35 and HCO3- is decreased then there is
primary metabolic acidosis
if pH is above 7.45 and POC2 is decreased it is
primary respiratory alkalosis
if pH is above 7.45 and HCO3- is increased it is
primary metabolic alkalosis.
anion gap formula is
Na+ - (HCO3- + Cl-)
the normal anion gap is
8-16mmol/l.
three main causes of a high anion gap acidosis
increased endogenous acid production.
increased exogenous acids.
inability to excrete acid.
i.e. increase in unmeasured anions - hydrogen ions reacting with bicarbonate ions.
two main causes of a normal anion gap acidosis
loss of bicarbonate, impaired renal excretion.
I.e. lost bicarbonate ions are replaced with chloride ions.
effect of low albumin on anion gaps
low albumin may have a normal anion gap in the presence of a disorder that produces a high anion gap.
respiratory acidosis metabolic compensation is
renal excretion of carbonic acid and re-absorption of bicarbonate is increased
in respiratory alkalosis metabolic compensation is
kidneys reduce reabsorption of bicarbonate and excretion of ammonium.
consider a mixed acid base disorder when
compensation is inadequate or excessive.
PCO2 and HCO3- concentrations become abnormal in opposite directions.
pH is normal but PCO2 or HCO3 concentration is abnormal (normal compensations rarely return pH to normal)
When the pCO2 is elevated and the HCO3- concentration is reduced =
respiratory acidosis and metabolic acidosis coexist
When the pCO2 is reduced and the HCO3- concentration is elevated
respiratory alkalosis and metabolic alkalosis coexist.
the A-a gradient is
difference between the calculated alveolar pO2 and the measured arterial pO2
A-a gradient calculation is
A-a gradient = alveolar pO2 - arterial pO2
alveolar Po2 =
PiO2 - arterial pCO2 x 1.2
Pio2 = effective inspired pO2
main causes of respiratory acidosis
depression of respiratory drive neuromuscular weakness chest wall abnormality disorder affecting gas exchange (COPD, asthma etc) Airway obstruction.
main causes of respiratory alkalosis
CNS stimulation (head trauma, hyperventilation, tumour)
Hypoxia (anaemia, high altitude)
Pulmonary disease
Drugs (Salicylates, aminophyllines)
main causes of metabolic alkalosis
hydrogen ion loss (Renal or GI) intracellular shift of hydrogen (Hypokalaemia) contraction alkalosis (Diuretics)
the axis is normal if the QRS complex is predominantly upwards in leads
1 and 2
left axis deviation occurs when the QRS complex is predominantly upwards in lead and downward in lead
upward lead 1 and downward lead 2
right axis deviation occurs when the QRS complex is predominantly downward in lead and upward in lead
downward lead 1 and upward lead 2
