Skill List > Fluid Balance – Monitoring
Clinical Alert
Elsevier Clinical Skills covers the principles of this procedure. You must follow local policies and procedures regarding technique, equipment used and documentation.
Based on Nicol: Essential Nursing Skills 4E
Adapted by Adele Hood
MAEd DipMidwifery Cert Ed PCeT RGN RM RT; Reviewed October 2014 by: Sue Faulds BSc(Hons) MA(Ed) DipHE RN
Updated by: Patricia Cronin BSc(Hons) MSc PhD DipN(Lond) RGN
Last updated: January 2017
Example of a fluid balance chart. (From Nicol M, Bavin C, Cronin P, et al. 2012 Essential Nursing Skills, 4th edn. Mosby Elsevier, Edinburgh.)
Learning Objective
After reading the skill overview, watching the video, following up some of the references/web sites and completing the self-test quiz you should be ready to be assessed in practice in the skill of monitoring fluid balance.


Fluid balance relates to the balance of fluid input and output in the body. Fluid intake should normally be balanced by fluid loss and this is described as being neutral balance. This state of normal or constant circulatory volume of fluid, known as euvolaemia, is maintained by a variety of hormonal mechanisms involving the central nervous system, the renal system and the adrenal cortex (McGloin 2015). The majority of water needed daily by the body is gained through ingestion of fluid (approximately 1600 mL) and food (approximately 700 mL) with the ‘thirst’ centre in the central nervous system being primarily responsible for its regulation (McGloin 2015). Thirst is a signal to the body to drink (McMillen & Pitcher 2011). 

The majority of fluid loss is through urine, which is regulated by the kidneys under the influence of hormones. Fluid may be lost through:

  • Urine
  • Faeces including ileostomy/colostomy output
  • Evaporation, via the skin or lungs
  • Blood loss, via haemorrhage or wound drains
  • Vomiting 
  • Nasogastric drainage.

Maintaining the correct balance of fluid in the body is essential for health and any fluctuation even by a small percentage (5–10%) can have adverse effects on the individual resulting in morbidity and even mortality (Johnstone et al. 2015, McMillen & Pitcher 2011, Pegram & Bloomfield 2015). A deficit in fluid volume is known as negative fluid balance and an excess is a positive fluid balance. 

Acutely ill patients become reliant on others to help them maintain their fluid balance and in particular an adequate fluid intake (McGloin 2015). Factors such as a loss of functional ability, cognitive impairment, physical weakness, refusing to drink, fasting, restricted fluid intake and nausea can all compromise adequate fluid intake. Excessive output can occur where the patient has, for example, diarrhoea and/or vomiting, polyuria, is on diuretics, has increased insensible loss (evaporation) or in cases of haemorrhage and severe burns (McMillen & Pitcher 2011, Shepherd 2011). 

In addition, the Francis report (2013) highlighted that older patients are at particular risk of dehydration, which is of key relevance given that the average age of hospitalised patients in the UK is over 80 (Cornwell 2012). Johnstone et al. (2015) recommend that if it is determined on admission assessment that an older person has difficulties drinking or accessing fluids independently that monitoring of fluid intake and output should be undertaken for the first 48 hours. 

Consistent concerns have been expressed about the poor management of fluid balance in the hospitalised patient. The National Confidential Enquiry into Patient Outcome and Death (NCEPOD) (2009) highlighted that poor fluid management and record keeping contributed to the worsening condition of the acutely ill patient. Aside from patient factors, it has been argued that healthcare professionals pay insufficient attention to accurate recording and maintenance of precise input and output is given a low priority (Francis 2013, McGloin 2015). These problems persist despite the introduction of strategies such as the Hospital Hydration Best Practice toolkit (Royal College of Nursing (RCN) & National Patient Safety Agency (NPSA) 2007). 

Enabling the patient to maintain a fluid balance is a key role of the nurse, which begins with accurate assessment. Accurate hydration assessment consists of three elements:

  • Clinical assessment e.g. assessing thirst, observing the mouth and tongue, assessing tissue turgor (poor elasticity of the skin can indicate dehydration)
  • Comprehensive cardiovascular assessment:
    • Blood pressure for detection of hypotension.
    • Manual pulse assessment for rate, strength and quality. A weak, thread pulse can indicate can be a sign of hypovolaemia.
    • Specific gravity of urine e.g. a raised SG can indicate concentrated urine due to dehydration.
    • Assessing capillary refill.
  • Daily weights taken at the same time, where, for example, weight gain in conjunction with other indicators can be a sign of fluid overload (Shepherd 2011, McGloin 2015, McMillen & Pitcher 2011).

However, all of the above must be undertaken in conjunction with the fluid balance chart and blood chemistry particularly sodium and creatinine (McGloin 2015). 

The fluid balance chart (Figure 1) is an essential component of fluid monitoring and should inform fluid prescribing and/or clinical interventions related to fluid loss or overload. The fluid balance chart is used to record the patient’s fluid input and output over a 24 h period at the end of which the total input and output is calculated to assess the patient’s overall fluid balance. This can be compared from day to day to assess whether the patient’s average fluid balance is positive, negative, or neutral. 

Common sources of error in fluid balance charting include duplication or omission of items, using estimates, not accounting for fluids administered elsewhere e.g. in the operating theatre, patients being unable to accurately recall their intake and using fluid remaining in a water jug as an accurate representation of fluid consumption (Cowen & Ugboma 2011, Francis 2013).

Fluid balance monitoring is clinically indicated across a range of conditions some of which are outlined in Box 1 although the list is not definitive and clinical judgement must always be made in individual situations. If the patient is on a fluid restriction (e.g., in renal failure), ALL oral fluids – including jelly, yoghurt, and milk with cereals must be recorded. 


Box 1 Indications for Fluid Balance Monitoring

  • A National Early Warning Score (NEWS) of >3
  • Early postoperative period
  • Dehydration/overhydration
  • First 48 hours following discharge from Critical Care
  • Fluid restrictions e.g. in renal failure
  • Intravenous fluid therapy
  • Parenteral/enteral nutrition
  • Pyrexia >38°
  • Sepsis
  • Urinary catheterisation
  • Where there is excessive fluid loss from diarrhoea/vomiting/nasogastric output/blood loss/surgical drains/ileostomies/colostomies
  • Where the patient is nil orally for longer than 12 hours

In health, the body produces 1 mL urine per kilogram of body weight per hour. However, in critically ill patients, an acceptable urine output is 0.5 mL per kilogram per hour (Cowen & Ugboma 2011). In these situations, it may be necessary to measure the urine every hour to ensure the kidneys are adequately perfused. If the patient’s output should drop below 0.5 mL per kilogram per hour it must be reported immediately. 

The Francis Report (2013) also highlighted that it is insufficient to simply monitor fluid intake and output and as part of the process patients should be encouraged to drink fluids. Part of this is to ensure patients  have easy access to fluids, can physically manage lifting a jug and have the dexterity to pour the fluid into a glass (Johnstone et al. 2015). Where this is not possible it is the role of the healthcare professional to ensure that the patient receives the necessary assistance. 

Preparation and safety

  • Explain the reason for monitoring fluid balance, and any activities that may be required of the patient.
  • Patients who are independent will be able to note the nature and measure the quantity of their oral fluid intake. If the patient is not independent, the nurse must do this.
  • For patients who have enteral and/or parenteral feeding, intravenous fluids, or wound drains, this must be recorded by the nurse.
  • Patients who are independent in meeting their elimination needs will often be able to measure and chart their own urine output. If the patient is unable to do this themselves, provide them with a clearly labelled jug to leave in the sluice or toilet area.
  • For some patients, especially those with renal failure, fluid balance is monitored by weighing the patient. Changes in weight will reflect fluid loss or gain.
  • Gloves and an apron should be worn when handling body fluids. 
  • Additional protective clothing may be necessary if indicated by the patient’s condition. 


  1. Gather any equipment that may be required to measure fluid output (e.g., jug) and protective equipment such as gloves and aprons. Rationale – Personal protective equipment is required when handling urine and other body fluids.
  2. Disinfect your hands and ask the patient about their oral intake. Rationale – Effective hand washing should always be undertaken prior to patient contact to minimise the risk of infections and cross-contamination.
  3. Dispose of any equipment and protective wear that may have been used when measuring fluid output. Rationale – Correct disposal of equipment minimises the risk of cross-contamination. The cleaning of the measuring jug will vary according to local policy. If disposable, it will be discarded. If not disposable, it may be disinfected, placed in a bedpan washer, or sent to the Sterile Supplies Department for decontamination.
  4. Complete fluid balance records in line with local policies and procedures and comply with any local guidance in relation to the management of fluid balance. Record all input including oral, enteral, parenteral, and intravenous intake on one side of the chart and all urine and any other output on the other side of the chart (Figure 1). Rationale – Accurate recording of all fluid input and output is essential to monitor the patient’s condition. Gaps in the chart (e.g., if the patient has been to theatre or for a test) will make the balance inaccurate and this should be noted.
  5. Document any abnormal findings in the patient’s record and inform the nurse in charge and medical staff. Rationale – Good communication and prompt reporting of abnormal findings will enable an effective plan of care for the patient.

Ongoing care, monitoring and support

  • If there is more intake than output, the patient is in a positive fluid balance. If there is more output than intake, the patient is in a negative fluid balance.
  • If the patient is on a fluid restriction, oral intake will include any fluids with food (e.g., milk with cereal).
  • Ensure the patient has access to fluids and where necessary provide assistance with pouring fluids into a glass or a drinking vessel appropriate to their needs. 
  • A new chart will be needed for each 24 h period. The fluid intake and output for the previous day is totalled and the balance is calculated. 
  • Record all oral, intravenous, and enteral and parenteral intake on the fluid intake side of the fluid balance chart.
  • In the output section, record all urine output, diarrhoea or stoma output, nasogastric aspiration, and vomit. Any other output that can be measured or weighed (e.g., wound drainage) must also be recorded. Most charts include a running total.
  • The sections labelled ‘Other’ can be annotated according to individual patient requirements (e.g., wound drainage).
  • Accurate recording of intake and output is vital to be able to calculate the fluid balance. Gaps in recording (e.g., if the patient has been to theatre or for a test) make the balance inaccurate. 
  • In acute situations, it may be necessary to measure the urine output every hour. A special drainage bag is used for hourly measurement. This incorporates a small reservoir in which urine can be measured and then emptied into the drainage bag without opening the ‘closed’ system (Nicol et al. 2012).

Documentation and reporting

  • Document fluid balance according to local policies and guidelines.
  • Report any abnormalities or complications.

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