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Module 4 : Case Scenarios

 

 

Case 2 : Perioperative loss

 

Your registrar calls you to tell you about a 70kg female patient who had an anterior resection 6 hours ago. The registrar says there was intraoperative blood loss of 800ml and that 500ml of Hartmanns was given by the theatre anaesthetist. He says the patient has an abdominal drain in situ which has produced 300ml of blood, but has now stopped draining. He mentions that the patient was euvolaemic prior to the operation.

 

The registrar says the patient is to remain nil-by-mouth in case she needs to go back to theatre. He asks you to prescribe more fluid for the patient, who has had only 500ml of normal saline since the operation.

 

 

  Test Yourself !  
   
  What's the first thing that you should do for this patient now?

How did you do?
 

Make sure you physically see the patient. Go to the bedside and examine the patient and check the blood results. Whenever taking a complex handover it is important to get as much information as possible. Speak to the nurse looking after the patient to see if they have any concerns, and speak to the patient / read the notes to find out if they have any important past medical history you should be aware of (eg heart or renal failure).

 
 

 

 

 

You go to see the patient who is alert but complaining of pain. You examine her and find her to be showing signs of hypovolaemia.

 

 

  Test Yourself !  
   
  What are the clinical signs of hypovolaemia ?

How did you do?
 

There are a number of clinical signs and symptoms. They are summarised in the table below:

 

 

It is worth noting that although hypotension is an important sign, this patient may have a normal or even high blood pressure, as he is complaining of pain.

 

 
 

 

 

 

You notice that the patient has a catheter in situ. The nurse tells you that this was placed by the anaesthetist pre-operatively. The catheter bag contains 100ml of concentrated urine.

 

 

  Test Yourself !  
   
  How much urine should have collected in the bag in the 6 hours since the operation? What could you do to confirm that the recorded urine output value of 100ml is correct?

How did you do?
 

The minimum acceptable urine output for adults with normal renal function is 0.5-1 ml/kg/hr. Below this the patient is likely to be in renal failure. In the last 6 hours this patient should have produced: 0.5 x 70 x 6 = 210ml minimum. If a patient has produced less than the minimum obligatory volume of urine this should prompt urgent intervention with a fluid challenge and senior input. However, it is a good idea to first check two things:

 

1. That the patient is not known to be in end stage renal failure and on dialysis– this could be a normal urine output for them! The place to look for this is in the notes, or ask the patient.

 

2. That the catheter bag has not simply been drained recently! Look at the fluid balance chart to check if there is any recorded urine output. In this case, the nurse tells you that she recently emptied the catheter bag, which contained 500ml of concentrated urine.

 
 

 

 

 

The patient tells you that she is still feeling very nauseous. She has a nasogastric tube in-situ, which has produced 300ml since the operation and is still producing large amounts of clear aspirate.

 

 

  Test Yourself !  
   
  Which important electrolyte is commonly lost in vomit and NG aspirate?

That's correct, well done!
 

Although many electrolytes are lost, the most problematic may be potassium. The loss of hydrochloric acid from the stomach may induce hypochloraemia and metabolic alkalosis. As a response to this, the kidneys increase the reabsorption of hydrogen ions from the tubules, at the expense of potassium which is exchanged and lost in the urine.

 

Barcarbonate is not usually lost from NG aspirate. More commonly it is lost in diarrhoea which may cause metabolic acidosis. The opposite is usually the case from NG losses.

 

Phosphate loss is not a common problem.

 

Sodium loss is not generally a problem with NG aspirate (see above).

 

Sorry, that's incorrect!
 

Although many electrolytes are lost, the most problematic may be potassium. The loss of hydrochloric acid from the stomach may induce hypochloraemia and metabolic alkalosis. As a response to this, the kidneys increase the reabsorption of hydrogen ions from the tubules, at the expense of potassium which is exchanged and lost in the urine.

 

Barcarbonate is not usually lost from NG aspirate. More commonly it is lost in diarrhoea which may cause metabolic acidosis. The opposite is usually the case from NG losses.

 

Phosphate loss is not a common problem.

 

Sodium loss is not generally a problem with NG aspirate (see above).

 

 

 

 

The nurse asks you what volume of fluid the patient is likely to need over the next 24 hours.

 

 

  Test Yourself !  
   
  Calculate the approximate fluid requirements for this patient, over the next 24 hrs.

How did you do?
 

This patient has clearly lost a lot of fluid, and a simple 3 L regimen is unlikely to be enough. Remember that when calculating fluid requirements you should try to account for previous losses and gains, present state of hydration, and anticipated future losses. The easiest thing to do is make a table of inputs and outputs since the patient was last known to be euvolaemic:

 

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As the patient was euvolaemic before the operation, we can calculate that at this point in time she is approximately 1000ml negative and this may explain her clinical signs of dehydration. Over the next 24 hours, if her NG output continues (in addition to urine output and insensible losses) we can anticipate fluid losses of approximately 3700ml, and as such we must replace this IV.

 

Therefore as the patient is currently in 1000ml negative balance with an anticipated future loss of 3700ml over the next 24hr, this would suggest that it would be necessary to replace at least 4700ml over the next 24hr.

 

As the patient is not known to have renal or cardiac failure it would seem reasonable to prescribe 5L (or more) of fluids over the coming 24 hours. However, the patient should have regular reassessment as the NG aspirate may reduce, or there may be third space losses to consider. This patient is also likely to have significant electrolyte dyscrasias, which should be carefully monitored and corrected as necessary.

 
 

 

 

 

You prescribe adequate replacement and maintenance fluids for the patient, and return regularly to review them. You also prescribe adequate analgesia and antiemetics. The patient's hydration improves and their pain settles. Everyone thinks you are a hero! But, just as you settle down in the mess for a well earned coffee, your on-call bleep chirps up…proceed to case 3!

 

 

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