Fluid and Electrolyte imbalance Cases Flashcards
A 72-year-old woman is found to be hypokalaemic. She had an elective right knee arthroplasty 3 days ago. Over the last 22 hours, she has developed vomiting and abdominal pain. Viral gastroenteritis is suspected, as other patients on the ward have been affected by the same symptoms.
On examination, her pulse is 88 beats/min and her blood pressure is 156/90 mmHg. Her mucous membranes are dry. Her serum potassium concentration is 2.3 mmol/L (3.5–4.7). The rest of her serum biochemistry is normal. The ECG shows small T waves.
What is the most appropriate initial treatment?
Co-amilofruse 5/40 1 tablet orally
Potassium chloride 40 mmol in 1 L of sodium chloride 0.9% IV over 2 hours
Potassium chloride 40 mmol in 1 L of glucose 5% IV over 1 hour
Potassium chloride/bicarbonate (Sando-K®) 3 tablets orally
Potassium chloride 40 mmol in 1 L of sodium chloride 0.9% IV over 2 hours
A 35-year-old woman is found to be hypotensive. She was admitted 6 hours ago with acute pancreatitis. Analgesia and intravenous fluids were administered and she was transferred to the ward. Over the past hour, her heart rate has been 100–110 beats/min and her blood pressure around 85/50 mmHg.
She has not passed any urine since admission. Her serum potassium concentration is 5.1 mmol/L (normal 3.5–4.7).
Compound sodium lactate (Hartmann’s solution) 500 mL IV over 10 minutes
Sodium chloride 0.9% 500 mL IV over 10 minutes
Human albumin solution 5% 250 mL IV over 10 minutes
Glucose 5% 500 mL IV over 10 minutes
Sodium chloride 0.9% 500 mL IV over 10 minutes
One of the nurses on the ward has asked you to prescribe fluids for a 63-year-old woman who has been admitted with suspected diverticulitis. She is currently nil-by-mouth.
- Date Time Volume Type of fluid Additives Rate Signature
- 10-January - 04:00 - 1L - 5% dextrose - 20 mmol potassium - 12 hours - Dr A Carr
- 10-January - 12:00 - 1L - 5% dextrose - 20 mmol potassium -12 hours - Dr S Merchant
You look up the latest U&Es on the computer:
- Na+139 mmol/l
- K+5.2 mmol/l
- Urea6.4 mmol/l
- Creatinine87 µmol/l
She weighs approximately 70kg. What is the most appropriate fluid to prescribe?
- 1 L 0.9% normal saline with no additives over 12 hours
- 1 L 5% dextrose with 20mmol potassium over 12 hours
- 1 L 5% dextrose with no additives over 12 hours
- 1 L 5% dextrose with 40mmol potassium over 12 hours
- 1 L 0.9% normal saline with 20mmol potassium over 12 hours
Her potassium is already high so potassium should be omitted.
1 L 0.9% normal saline with no additives over 12 hours
Fluid therapy:
The prescription of intravenous fluids is one of the most common tasks that junior doctors need to do.
In the 2013 guidelines NICE recommend the following requirements for maintenance fluids:
- 25-30 ml/kg/day of water and
- approximately 1 mmol/kg/day of potassium, sodium and chloride and
- approximately 50-100 g/day of glucose to limit starvation ketosis
So, for a 80kg patient, for a 24 hour period, this would translate to:
- 2 litres of water
- 80mmol potassium
For the first 24 hours NICE recommend the following::
- When prescribing for routine maintenance alone, consider using 25-30 ml/kg/day sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium on day 1 (there are other regimens to achieve this).
- The amount of fluid patients require obviously varies according to their recent and past medical history. For example a patient who is post-op and is having significant losses from drains will require more fluid whereas a patient with heart failure should be given less fluid to avoid precipitating pulmonary oedema.
The table below shows the electrolyte concentrations (in millimoles/litre) of plasma and the most commonly used fluids:
- Na+ Cl- K+ HCO3- Glucose
- Plasma 135-145 98-105 3.5-5 22-28 -
- 0.9% saline 154 154 - - -
- 5% glucose - - - - 50g
- 0.18% saline with 4% glucose 30 30 - - 40g
- Hartmann’s solution 131 111 5 29 -
Specific points:
0.9% saline
- if large volumes are used there is an increased risk of hyperchloraemic metabolic acidosis
Hartmann’s
- contains potassium and therefore should not be used in patients with hyperkalaemia
You have been bleeped whilst on-call to prescribe fluids a 79-year-old man who is nil-by-mouth following a stroke. He weighs around 80kg. His fluid chart is as follows:
- DateTimeVolumeType of fluidAdditivesRateSignature
- 4-March12:00 1L0.9% saline20 mmol potassium10 hoursDr P Calf
- 4-March20:00 1L0.9% saline20 mmol potassium10 hoursDr S Coogan
A nurse has attached a copy of his latest U&Es:
- Na+140 mmol/l
- K+4.2 mmol/l
- Urea5.4 mmol/l
- Creatinine98 µmol/l
What is the most appropriate fluid to prescribe?
- 1 L 0.45% saline with no additives over 10 hours
- 1 L 5% glucose with 40mmol potassium over 10 hours
- 1 L 5% glucose with 60mmol potassium over 10 hours
- 1 L 0.9% saline with no additives over 10 hours
- 1 L 0.9% saline with 20mmol potassium over 10 hours
1 L 0.9% saline with 20mmol potassium over 10 hours.
5% glucose should be avoided in patients who have had a stroke due to the increased risk of cerebral oedema. Prescribing a further bag of 0.9% normal saline with maintenance potassium is therefore the most appropriate course of action.
From the American Stroke Association guidelines: For non-hypoglycemic patients, excessive dextrose-containing fluids have the potential to exacerbate cerebral injury; thus, normal saline is more appropriate if rehydration is required
The prescription of intravenous fluids is one of the most common tasks that junior doctors need to do.
In the 2013 guidelines NICE recommend the following requirements for maintenance fluids:
- 25-30 ml/kg/day of water and
- approximately 1 mmol/kg/day of potassium, sodium and chloride and
- approximately 50-100 g/day of glucose to limit starvation ketosis
So, for a 80kg patient, for a 24 hour period, this would translate to:
- 2 litres of water
- 80mmol potassium
For the first 24 hours NICE recommend the following::
- When prescribing for routine maintenance alone, consider using 25-30 ml/kg/day sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium on day 1 (there are other regimens to achieve this).
- The amount of fluid patients require obviously varies according to their recent and past medical history. For example a patient who is post-op and is having significant losses from drains will require more fluid whereas a patient with heart failure should be given less fluid to avoid precipitating pulmonary oedema.
A 68-year-old woman has been admitted to the acute medical unit with severe diarrhoea and dehydration. Her admission U&Es (taken yesterday) are shown below:
- Na+142 mmol/l
- K+4.9 mmol/l
- Urea18.3 mmol/l
- Creatinine128 µmol/l
Her most recent U&Es (taken 4 hours ago) are shown below:
- Na+144 mmol/l
- K+4.0 mmol/l
- Urea12.1 mmol/l
- Creatinine99 µmol/l
Her fluid chart is shown below:
- DateTimeVolumeType of fluidAdditivesRateSignature
- 9-June11:001 L0.9% normal saline-2 hoursDr J Smith
- 9-June13:001 L0.9% normal saline-4 hoursDr J Smith
- 9-June20:001 L0.9% normal saline-8 hoursDr J Smith
She weighs approximately 70kg. What is the most appropriate fluid to prescribe?
- 1 L 5% dextrose with 20mmol potassium over 4 hours
- 1 L 5% dextrose with 20mmol potassium over 8 hours
- 1 L 0.9% normal saline with 20mmol potassium over 4 hours
- 1 L 5% dextrose with no additives over 8 hours
- 1 L 0.9% normal saline with no additives over 4 hours
1 L 5% dextrose with 20mmol potassium over 8 hours
The initial potassium was borderline high which probably explains why Dr Smith didn’t prescribe any additives. It is now well within the normal referance range and should be added to future bags. Whilst the U&Es still look ‘dry’ (the urea:creatinine ratio is greater than 10) it is clearly improving and doesn’t warrant the fluids being given 4 hourly again.
The prescription of intravenous fluids is one of the most common tasks that junior doctors need to do.
In the 2013 guidelines NICE recommend the following requirements for maintenance fluids:
25-30 ml/kg/day of water and
approximately 1 mmol/kg/day of potassium, sodium and chloride and
approximately 50-100 g/day of glucose to limit starvation ketosis
So, for a 80kg patient, for a 24 hour period, this would translate to:
2 litres of water
80mmol potassium
For the first 24 hours NICE recommend the following::
- When prescribing for routine maintenance alone, consider using 25-30 ml/kg/day sodium chloride 0.18% in 4% glucose with 27 mmol/l potassium on day 1 (there are other regimens to achieve this).
- The amount of fluid patients require obviously varies according to their recent and past medical history. For example a patient who is post-op and is having significant losses from drains will require more fluid whereas a patient with heart failure should be given less fluid to avoid precipitating pulmonary oedema.
https://www.nice.org.uk/guidance/cg174/chapter/1-Recommendations
A 40-year-old man is admitted to the short stay acute medical unit with vomiting and abdominal pain. He had eaten a chicken curry a few hours prior to this. He has no medical conditions and is otherwise fit and well. His blood results are as follows:
- Na+135 mmol/L(135 - 145)
- K+3.1 mmol/L(3.5 - 5.0)
- Bicarbonate24 mmol/L(22 - 29)
- Urea7.6 mmol/L(2.0 - 7.0)
- Creatinine130 µmol/L(55 - 120)
He requires fluid replacement and 1L of 0.9% sodium chloride supplemented with 40 mmol of potassium is prescribed.
What is the shortest time period over which this bag of fluid can be administered safely?
- 30 minute
- 1 hour
- 2 hours
- 4 hours
- 6 hours
4 hours
The maximum recommended rate of potassium infusion via a peripheral line is 10 mmol/hour, whereas rates above 20 mmol/hour require cardiac monitoring
Important for meLess important
The blood results show that he has an acute kidney injury, likely secondary to vomiting, and hypokalaemia. Therefore, he requires fluid replacement with potassium supplementation.
The maximum rate of potassium infusion via a peripheral line is 10 mmol/hour on a standard ward. 40 mmol of potassium over 4 hours equates to 10 mmol of potassium per hour. Therefore the answer is 4 hours.
30 minutes, 1 hour and 2 hours would correspond to a rate of potassium infusion that is faster than 10 mmol/hour. The danger of giving potassium too quickly is that it can cause cardiac arrhythmias. In the intensive care unit where there is extensive cardiac monitoring, potassium may be given at a faster rate if needed.
Giving this bag of fluid over 6 hours would be safe to prescribe, however the questions asks for the shortest time period over which the bag can be given.
A 67-year-old lady is discovered to have a creatinine of 137 micromols/L one day after her emergency Hartmann’s procedure for an obstructing distal colonic tumour. Her baseline creatinine is around 86 micromols/L.
Her observations include a heart rate of 98 beats per minute, blood pressure of 96/70 mmHg, respiratory rate of 24 breaths per minute and oxygen saturation of 95% on room air. She is catheterised and her fluid balance chart shows that she has only passed 100mL of urine in the past 6 hours.
What would be the most appropriate way to administer initial fluids?
- 500mL 0.9% saline over 15 minutes
- 500mL 5% dextrose over 15 minutes
- 1L 0.9% saline over 15 minutes
- 1L 0.9% saline over 8 hours
- 500mL 0.9% saline over 30 minutes
500mL 0.9% saline over 15 minutes
This woman has a pre-renal AKI, which is likely secondary to the major surgery she has recently had, where she may have lost a lot of blood or been prescribed insufficient fluids. She is therefore now hypovolaemic and requires intravenous fluid resuscitation.
For intravenous fluid resuscitation, NICE recommend using a crystalloid containing sodium in the range of 130-154mmol/L, with an initial bolus of 500mL over less than 15 minutes. Hartmann’s solution contains potassium, therefore in the setting of an acute kidney injury, it might be more appropriate to give 0.9% saline, which does not contain any potassium, since hyperkalaemia is a concern in AKI.
Reference: NICE 2013 Intravenous fluid therapy in adults in hospital
The staff nurse on a stroke rehabilitation ward has asked you to prescribe fluids for a 66-year-old woman with dysphagia. She weighs 71kg. She has had three episodes of diarrhoea in the last 48 hours however is currently haemodynamically and clinically stable.
Most recent blood report:
- Na+138 mmol/L(135 - 145)
- K+4.2 mmol/L(3.5 - 5.0)
- Bicarbonate26 mmol/L(22 - 29)
- Urea6.1 mmol/L(2.0 - 7.0)
- Creatinine101 µmol/L(55 - 120)
When prescribing maintenance fluids for this woman, what is the recommended water requirement?
- 10-15 ml/kg/day
- 15-20 ml/kg/day
- 20-25 ml/kg/day
- 25-30ml/kg/day
- 30-35 ml/kg/day
When prescribing maintenance fluids, 25-30 ml/kg/day of water is typically required
A 23-year-old male victim of an acid attack attends the resus department, he has burns on an estimated 25% of his body surface area and weighs 60kg.
The Parkland formula is used to calculate the amount of fluid resuscitation necessary over the next 24 hours for this patient according to his weight and surface area affected by burns.
What volume of fluid resuscitation should he be given over the next 24 hours?
- 6000mls
- 1500mls
- 2000mls
- 7500mls
- 3000mls
6000mls
The Parkland formula for fluid resuscitation in burns is:
- Volume of fluid = total body surface area of the burn % x weight (Kg) x 4ml
Indication: >15% total body area burns in adults (>10% children)
- The main aim of resuscitation is to prevent the burn from deepening
- Most fluid is lost 24h after injury
- First 8-12h fluid shifts from intravascular to interstitial fluid compartments
- Therefore circulatory volume can be compromised. However fluid resuscitation causes more fluid into the interstitial compartment especially colloid (therefore avoided in first 8-24h)
- Protein loss occurs
Fluid resuscitation formula
- Parkland formula (Crystalloid only e.g. Hartman’s solution/Ringers’ lactate)
- 50% given in first 8 hours then 50% given in next 16 hours
- Resuscitation endpoint: Urine output of 0.5-1.0 ml/kg/hour in adults (increase rate of fluid to achieve this)
Points to note:
- Starting point of resuscitation is time of injury
- Deduct fluids already given
After 24 hours:
- Colloid infusion is begun at a rate of 0.5 ml x(total burn surface area (%))x(body weight (kg))
- Maintenance crystalloid (usually dextrose-saline) is continued at a rate of 1.5 ml x(burn area)x (bodyweight)
- Colloids used include albumin and FFP
- Antioxidants, such as vitamin C, can be used to minimize oxidant-mediated contributions to the inflammatory cascade in burns
- High tension electrical injuries and inhalation injuries require more fluid
- Monitor: packed cell volume, plasma sodium, base excess, and lactate
An 8-year-old is admitted with suspected appendicitis and has a laparoscopic appendicectomy. He is given 0.45 % sodium chloride post-operatively. When reviewed by the surgical team he has developed features of a headache, confusion, and disturbance to his gait.
- Na+128 mmol/l
- K+4.0 mmol/l
- Urea5 mmol/l
- Creatinine60µmol/l
- Glucose4.0mmol/l
Which of the following is the most likely diagnosis?
- Adverse reaction to patient controlled analgesia
- Hyperosmolar hyperglycaemic state
- Hyponatraemic encephalopathy
- Normal pressure hydrocephalus
- Central pontine myelinolysis
- Avoidance of using hypotonic (0.45%) in paediatric patients - risk of hyponatraemic encephalopathy
In paediatric patients, there are at higher risk of hyponatraemic encephalopathy. This is most noted in those who receive hypotonic intravenous fluids such as 0.45% sodium chloride. There is a second reason for the hyponatraemia in this patient, a well documented cause of SIADH is trauma and stress. ADH secretion lowers serum sodium levels through opening aquaporin channels allowing water to move into the intravascular space.
Central pontine myelinolysis is a consequence of rapidly correctly hyponatraemia which is not the case here
Excessive use of patient controlled analgesia could result in a reduced conscious level and respiratory depression especially if opiates such as morphine were prescribed
Hyperosmolar hyperglycaemic state is a complication of diabetes mellitus and can result in reduced conscious level - however by analysing the blood test results the random glucose level is normal.
Gait disturbance is a feature of normal pressure hydrocephalus but in association with dementia and urinary incontinence
An 18 year old man is brought into the Emergency Department after being injured in a pub-brawl. He complains of abdominal pain. On examination the abdomen is bruised and tender. His heart rate is 136 beats per minute and blood pressure is 72/54mmHg. Which fluid would be most suitable for resuscitation?
- 500 mls of Gelofusin over 15 minutes
- 500 mls 0.9% Sodium Chloride over 15 minutes
- 500 mls of Plasmalyte over 30 minutes
- 500 mls 10% dextrose over 15 minutes
- 500 mls Hypertonic saline over 15 minutes
500 mls 0.9% Sodium Chloride over 15 minutes
- For resuscitation, the NICE guidelines advocate a crystalloid that contain sodium in the range 130 to 154 mmol/l, with a bolus of 500 ml over no more than 15 minutes.
- Gelofusine contains 154mmol/L of sodium but is a colloid, invalidating this option.
- 10% dextrose contains no sodium, invalidating this option.
- Hypertonic salines contain sodium at a concentration greater than 154mmol/l, invalidating this option.
- Plasmalyte contains 140 mmol/l of sodium so would be an option but not at the rate offered here.
A 47-year-old male has been nil by mouth for 3 days awaiting bariatric surgery that has been repeatedly postponed, he is to be prescribed IV dextrose to ensure his glucose requirements are being met.
His weight is 150kg, which of the following is an acceptable daily amount of glucose for him to be given?
- 25mg
- 100g
- 100mg
- 150g
- 150mg
100g is the only possible correct answer, his weight is irrelevant.
When prescribing fluids, the glucose requirement is 50-100 g/day irrespective of the patient’s weight
You are the foundation doctor covering surgery. You are asked to review a 77 year old patient (75kg) who is post right hemicolectomy for bowel cancer. The patient is hypotensive (87/40 mmHg), tachycardia (128 bpm) and has a urine output of 25 mls per hour. His only past medical history is hypertension. You conduct a fluid assessment. He appears dry with sunken eyeballs and reduced skin turgor. You want to conduct a fluid challenge to assess his response. What is the most appropriate fluid to px?
- 1 Litre of gelofusin
- 1 Litres 0.9% normal saline over 8 hours
- 500 mls 0.9% normal saline STAT
- 500 mls 0.9% normal saline over 8 hours
- 250 mls 0.9% normal saline STAT
500 mls 0.9% normal saline STAT
- In patients with no clinical signs or documentation of heart failure a 500 ml prescription of normal saline delivered STAT is the recommended fluid challenge. You must remember to reassess the patient to decide whether to prescribe another 500 mls.
- 250 mlx of 0.9% Normal Saline would be appropriate in patients with evidence of heart failure. This does not put as much strain on their physiology and risk the patient devoting worsening cardiac failure.
A 17-year-old man undergoes an elective right hemicolectomy. Post operatively he receives a total of 6 litres of 0.9% sodium chloride solution, over 24 hours. Which of the following complications may ensue?
- Hyperchloraemiac acidosis.
- Hypochloraemic alkalosis
- Hyperchloraemic alkalosis
- Acute renal failure
- None of the above
Hyperchloraemiac acidosis.
Excessive infusions of any intravenous fluid carry the risk of development of tissue oedema and potentially cardiac failure. Excessive administration of sodium chloride is a recognised cause of hyperchloraemic acidosis and therefore Hartmans solution may be preferred where large volumes of fluid are to be administered.
The actual explanation is b/c when you have increased chloride, your body needs to maintain electroneutrality by secreting other anions, which is your bicarb. Hence you got hyperchloraemic (high Cl) acidosis (resulting in reduced bicarb, hence can be classified under NAGMA as well)
Increased chloride. Kidney removes bicarbonate to maintain electroneutrality –> low bicarbonate –> acidosis.
