Fluid management Flashcards
What are the three main purposes of fluid prescription in hospitalized patients?
Resuscitation – Restore intravascular volume and improve perfusion.
Maintenance – Meet daily physiological needs when oral intake is insufficient.
Replacement – Compensate for ongoing or anticipated fluid losses.
Name three key factors to consider before prescribing fluids.
Patient’s weight and size.
Presence of comorbidities (e.g., heart failure, CKD).
Reason for admission and clinical status.
Why is fluid management particularly important in peri-operative care?
Proper fluid and haemodynamic management reduces post-operative morbidity and length of hospital stay.
What proportion of total body weight is water?
Approximately 2/3 of total body weight is water.
How is total body water distributed between intracellular and extracellular compartments?
2/3 intracellular.
1/3 extracellular (of which: 1/5 is intravascular, 4/5 is interstitial).
Why do septic patients often require large volumes of IV fluids?
Sepsis increases vascular permeability, leading to fluid leakage into tissues. Large volumes are needed to maintain intravascular volume despite high total body water.
According to NICE guidelines, what are the daily maintenance fluid requirements for a 70 kg adult?
Water: 1750 mL (25 mL/kg/day).
Sodium: 70 mmol (1 mmol/kg/day).
Potassium: 70 mmol (1 mmol/kg/day).
Glucose: 50 g/day.
Outline a typical 24-hour maintenance fluid regimen for a 70 kg adult.
500 mL 0.9% saline with 20 mmol K+ over 8 hours.
1 L 5% dextrose with 20 mmol K+ over 8 hours.
500 mL 5% dextrose with 20 mmol K+ over 8 hours.
How is fluid deficit commonly assessed in clinical practice?
Subjectively based on:
Clinical parameters (e.g., dry mucous membranes, low urine output).
Patient size and comorbidities.
What urine output should trigger concern for fluid deficit in adults?
Urine output < 0.5 mL/kg/hour.
Describe a typical fluid challenge in a patient with low urine output.
250–500 mL of IV fluid over 15–30 minutes, depending on patient size and comorbidities.
What are some common causes of ongoing fluid losses?
Third-space losses (e.g., bowel obstruction, pancreatitis).
Diuresis.
Increased stool output (e.g., diarrhea, high stoma output).
Fever or tachypnoea increasing insensible losses.
Which electrolyte abnormalities are commonly seen with vomiting?
Low potassium (K+).
Low chloride (Cl−).
Alkalosis.
What clinical signs indicate fluid depletion?
Dry mucous membranes.
Reduced skin turgor.
Decreased urine output (< 0.5 mL/kg/hr).
Orthostatic hypotension.
Tachycardia and low blood pressure in severe cases.
What are common signs of fluid overload?
Raised JVP.
Peripheral or sacral oedema.
Pulmonary oedema (e.g., crackles on auscultation).
What tools should be used to monitor a patient’s fluid status?
Fluid input-output charts.
Daily weight charts.
Urea & Electrolytes (U&Es).
What are the two main categories of IV fluids?
Crystalloids – e.g., 0.9% saline, Hartmann’s, 5% dextrose.
Colloids – e.g., albumin, gelatins (rarely used now).
Why are crystalloids preferred over colloids for resuscitation?
Cheaper and widely available.
No significant clinical benefit of colloids over crystalloids.
Similar effectiveness in replenishing intravascular volume.
What is the primary purpose of 5% dextrose?
To provide free water and glucose for metabolism, not for significant intravascular volume expansion.
What is the composition of 0.9% saline?
Sodium: 154 mmol/L.
Chloride: 154 mmol/L.
No glucose.
Why might a patient be kept ‘on the dry side’ post-operatively?
To reduce the risk of complications such as pulmonary oedema and wound dehiscence.
Why is careful fluid management important in patients with heart failure or CKD?
These patients are at higher risk of fluid overload and electrolyte imbalances.
What are the NICE guidelines for daily maintenance of water, sodium, potassium, and glucose?
Water: 25 mL/kg/day.
Sodium: 1 mmol/kg/day.
Potassium: 1 mmol/kg/day.
Glucose: 50 g/day.
Why is it important to reassess fluid prescriptions regularly?
To adapt to the patient’s changing clinical condition.
To prevent complications like fluid overload or dehydration.
