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Fluid Balance

Fluid balance can alter with disease and illness so it important to be aware of how much fluid is in the body, taking steps such as measuring urea and electrolytes levels

Author

Gail P. Mooney, MSc, PG Social Research Methods, RGN, lecturer, School of Health Science, University of Wales, Swansea.

 

Body fluids are regulated by fluid intake, hormonal controls, and fluid output (Potter and Perry, 2001).

Normal/ideal values

Approximately 60% of body weight in males constitutes total body fluid, with 52% in females. A reduction in body fluids can have major effects on the body: a reduction of 5% will cause thirst, a reduction of 8% will cause illness and a 10% reduction in fluid can cause death (Carroll, 2000). Age, gender and body fat influence the proportion of body fluid.

Disturbance in fluid balance

Hypovalemia is the term used for loss of fluid and hypervalemia is the term used when a patient has fluid overload.

There are a number of factors that will cause fluid loss and gain:

Loss

  • Diarrhoea;
  • Vomiting;
  • Sweating/fever;
  • Haemorrhage;
  • Diuretics;
  • Excessive urination.

Gain

  • Congestive cardiac failure;
  • Renal failure;
  • High sodium intake;
  • Cirrhosis of the liver;
  • Over infusion of intravenous fluids.

All of the above can be symptoms of disease and illness.

Another factor in fluid loss to consider is the patient’s physical mobility/abilities. If a patient is physically disabled they may not be able to access fluid. A patient who has had a cerebral vascular accident may not be able to physically take and drink the fluid. Some patients with continence problems may restrict their fluid intake believing this will alleviate the problem.

Recording fluid balance

The nursing assessment of fluid balance should include: the patient’s history, physical examination, clinical observation and interpretation of laboratory results (Place and Field, 1997).

A detailed account of the patient’s history should be taken especially the fluid intake and output. The nurse may have to rely on relatives and carers to give this information if the patient is unable to.

A clinical assessment of the patient should be carried out including vital observations such as measuring the blood pressure, pulse, respiration and temperature. The patient’s physical appearance should be noted: attention should be paid to the skin, tongue and face. The general well being of the patient is also a good indication of fluid loss or gain.

Central venous pressure (CVP) is a measurement of pressure in the right atrium of the heart. The CVP recording is a good indication to determine the amount of fluid contained within the body.

Table 1 gives an indication of clinical assessment made possible through measuring fluid balance (Place and Field, 1997).

Table 1. Observations related to fluid balance

 

 

Observation

 

 

Fluid depletion

 

 

Fluid overload

 

 

Weight

 

 

Loss

 

 

Gain

 

 

Blood pressure

 

 

Lowered smaller pulse pressure

 

 

Normal or raised

 

 

Respirations

 

 

Rapid, shallow

 

 

Rapid, moist cough

 

 

Pulse

 

 

Rapid, weak, thready

 

 

Rapid

 

 

Urine output

 

 

Reduced, concentrated

 

 

Increased or decreased if heart is failing

 

 

Skin

 

 

Dry, less elastic

 

 

Oedematous

 

 

Saliva

 

 

Thick, viscous

 

 

Copious, frothy

 

 

Tongue

 

 

Dry, coated

 

 

Moist

 

 

Thirst

 

 

Present

 

 

No disturbance

 

 

Face

 

 

Sunken eyes (severe depletion)

 

 

Peri-orbital oedema

 

 

Temperature

 

 

May be raised

 

 

No disturbance

 

 

Patients with an imbalance in body fluid, whether loss or gain, would present with more than one of the above symptoms.

Patients’ intake and output are recorded on fluid balance charts, and accurate recording is crucial for their wellbeing. Output is often recorded as passed urine ++ or up to toilet, which is far from accurate and does not give a clear indication of the amount of urine passed.

An imbalance of electrolytes in the blood can cause fluid imbalance. Laboratory blood tests such as urea and electrolytes, glucose, magnesium, calcium will determine discrepancies and govern the treatment required to resolve the problem (Table 2) (Sheppard, 2000).

 

Table 2. Laboratory results associated with fluid imbalance

 

 

Fluid loss

 

 

Fluid gain

 

 

  • Increased serum osmolality
  • High urine osmolality and specific gravity
  • Raised haematocrit
  • Increased plasma-urea concentration

 

 

  • Reduced plasma urea
  • Reduced haematocrit

 

 

When and how often should the fluid balance be recorded?

Fluid balance is continually monitored on those patients who have already shown signs and symptoms of fluid imbalance. Other patients at risk, such as those in critical care or who have just undergone surgery, should be closely monitored.

Safety

  • Accurate measurement in the recording of patients’ intake and output is crucial to the patient’s wellbeing;
  • Close monitoring and observation of the patient will provide early detection of fluid imbalance;
  • Close monitoring of patients who are administered diuretics is essential.

References

Carroll, H. (2000) In: Sheppard, M., Wright, M.(eds) Principles and Practice of High Dependency Nursing. Edinburgh: Baillière Tindall.

Place, B., Field, D. (1997) The management of fluid balance. Nursing Times; 93: 44, 46-48.

Potter, P.A., Perry, A.G. (2001) Fundamentals of Nursing (5th ed). Mosby: Mo: St Louis.

Sheppard, M. (2000) Monitoring fluid balance in acutely ill patients. Nursing Times; 96: 21, 39-40.

 

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