Water (hydration) is an essential component for life — any deficiency in hydration may result in serious illness or death. There are several groups of patients/clients/residents who are considered high risk when maintaining hydration. These groups include the elderly, frail, very young, or those with significant disabilities (Morris and McKinlay, 2016).  
Fluid balance monitoring tools/charts have been used for several decades in both acute and community care settings and provide a way of recording all fluid intake and output. Different versions are available for the various healthcare settings, depending on the reason for monitoring. Data collected may be used to determine intravenous (IV) fluid replacement needs, the general health of the individual, or as an aid to diagnosing a number of conditions affecting the bladder and other bodily functions. 
Fluid balance charts, in any format, are therefore important documents in health and social care environments (Daffurn et al, 1994; Tang and Lee, 2010; Vincent and Mahendiran, 2015). Although completion of intake/output charts is seen as a routine nursing activity (Davies et al, 2015), historically, fluid balance charts have been poorly maintained (Perren et al, 2011), with time to complete and lack of understanding or awareness cited as reasons for the poor compliance (Abrams et al, 2013; Jeyapala et al, 2015; Williamson et al, 2019).  
The Royal College of Nursing (RCN) and National Patient Safety Agency (NPSA) introduced a hospital hydration best practice toolkit, Water for Health (RCN and NPSA, 2007), in response to earlier statistical evidence of poor practice. However, in 2020, significant issues are still being seen.  
The Francis Report (2013) identified multiple episodes in the Mid Staffordshire Trust Enquiry where patients were left without access to food and drink or assistance to consume it. A current high profile media case reporting the tragic events surrounding the death of a young autistic man suggests dehydration and malnutrition were contributory to his death in an NHS hospital (BBC December 2019). Statistics published by the Office for National Statistics (ONS) recorded 100–113 deaths attributed to dehydration or malnutrition in care homes and hospitals in England and Wales in 2014 and 2015 (ONS, 2019). These are a shocking reflection of potential neglect in areas where people are supposed to be supported in times of need or illness.  


Fluid balance, frequency volume or input and output charts, and bladder diaries — the terminology varies, but does it mean the same thing? The information contained in each of these charts is essentially a record of what goes in and what comes out. Fluid balance charts have been a traditional component of hospital care for decades and, as said, the interpretation of the data varies dependent on the reason for monitoring. Recording exactly what fluid is given to a patient and how much output is collected from the bladder and any surgical drains is a valuable source of information regarding a patient’s stability in acute areas such as theatre, intensive care units (ICU), and post-surgery. In these situations, an accurate fluid balance record will help determine appropriate prescribing of replacement fluids essential for homeostasis and healing (Davies et al, 2017). Frequency volume charts are a standard component of urology, gynaecology and specialist continence/bladder/bowel services, as these determine how often someone passes urine, and can offer a direct comparative to how much is drunk, activity at different times within a 24-hour period and effect on bladder symptoms, leading to a diagnosis and appropriate reaction or treatment options.  
Many individual patients complete a frequency volume chart at home before attending a specialist service appointment. However, completion of fluid balance charts in community settings for the housebound patient can be difficult to maintain, as care providers may vary or visit infrequently. Community nursing is aimed at maintaining normality as much as possible in the home dwelling, therefore too many charts/records may seem to be over medicalising the home environment. In the author’s opinion, the challenges in maintaining effective charts should not negate the use of fluid intake and output charts, as they still form an important element of community care. For example, many areas complete a trial without catheter (TWOC) procedure in community settings, which requires a degree of intake and output monitoring to establish successful outcomes.  
However, all versions of charting fluid intake and output only capture what can be easily measured, insensible fluid loss through respiration or perspiration cannot be accurately predicted and therefore may affect the accuracy of the data collected (Davies et al, 2015).  


Fluid balance has been determined as the dynamic balance between the volume of water lost from the body and water gained (Totora and Derrickson, 2012). The majority of fluid intake for most of us is oral ingestion. It is widely accepted that an average size adult with moderate activity levels needs 1500mls a day oral fluid to maintain homeostasis (Abrams et al, 2013), with a further 700mls potentially from food (McMillen and Pitcher, 2010). The central nervous system regulates the volume with a further 200mls fluid deriving from the metabolic synthesis associated with aerobic respiration. This equates to 20 litres of circulating fluid filtered throughout the capillaries and lymphatic system, maintaining effective circulation and intracellular fluid in the healthy person (Clancy and McVicar, 2009).  
Dehydration occurs when fluid loss results in 1% (or greater) loss of body weight (Madden, 2000). When a person becomes dehydrated, cognitive function deteriorates with increasing confusion, reduced activity levels, and drying mucosal tissue, leading to more susceptibility to tissue damage. The circulatory blood volume is also compromised leading to increased heart and respiratory rate, a decrease in blood pressure and central venous pressure, and reduced cardiac output (Madden, 2000).  
Accurate monitoring of fluid balance in an acutely ill patient is essential to manage IV or diuretic administrations (National Institute for Health and Care Excellence [NICE], 2013), but is open to error. Hypovolaemia, i.e. decreased intravascular volume, leads to acute kidney injury, and can result in pulmonary or peripheral oedema and an increased risk of hospital-acquired infections (HAIs), impaired healing and pressure damage to skin (Vincent and Mahendiran, 2015).  
Additional monitoring of fluid balance can be managed with body weight measurements, as accuracy is determined as a 1kg body weight gain/loss equating to 1L of fluid gain/ loss (Eastwood, 2006). Over short timescales, e.g. 0–7 days, changes in body weight are almost certainly due to an alteration in body fluid. Body weight becomes a less reliable tool for fluid balance monitoring after seven days, as weight loss/gain is affected by muscle and fat loss (Lavery et al, 1996). Therefore, the combined use of monitoring tools, including fluid balance and body weight changes, is a more effective way of managing the critically ill patient in the short term (Freitag et al, 2010). In the author’s clinical experience, body weight monitoring may also have a positive impact on managing patients with renal, respiratory or cardiac failure, but should not be used in isolation of other clinical assessment tools.  
A frequency volume chart is an essential part of assessment of lower urinary tract symptoms in a non-acute patient and can aid diagnosis and guide treatment (NICE, 2010). These charts are usually completed by the patient and should cover a minimum of three days to ensure that the data is meaningful and relevant (NICE, 2013). Where possible, a mix of both work and leisure time should be covered by the chart, as bladder behaviour may vary dependent on daily routine. The days do not have to be consecutive, and compliance may improve if patients are able to choose dates when they can manage data collection more easily, based on practical factors such as work or leisure.  


The first consideration would be who will complete the chart and in what environment. The accuracy of fluid charts is often called into question with entries missing or ‘passed urine in toilet’ a common feature. It is also difficult to monitor accurate output when a patient suffers incontinence or is confused. Patients trying to maintain an accurate bladder diary when at work or school can present challenges, including how to collect the information discreetly when using a public toilet. 
It is important on any version of the charts to record the: 
  • Time that urine is passed (or a catheter is emptied)  
  • Amount of volume passed in millilitres  
  • Amount of fluids entering the body  
  • Time the fluids are administered/ingested
This provides a pattern over a 24-hour period and can be useful in determining normal function, bladder behaviour, and kidney function. Any other excess fluid loss, such as profuse diarrhoea or wound loss, should also be recorded. All supplementary fluids that may be administered intravenously or via nasogastric or percutaneous endoscopic gastrostomy (PEG) tube should also be included on the charts. The charts offer a more accurate indicator of fluid status if recorded over several days, rather than a snapshot of 24 hours (Abrams and Klevmark, 1996; Dmochowski et al, 2005; McGloin, 2015), as the longer timescale allows for variations in daily activity and interventions.  
Compliance when completing charts can be an issue when patients or a variety of staff are involved in collecting and recording the data (Colley, 2015). There may be a variation in the accuracy of the measuring container used (British Standards International Organisation for Standardisation [BS ISO], 1985), as passing urine into a jug can affect dignity and is not the most discreet process to maintain for individuals. Remembering to record an essentially normal function that we usually take for granted can also cause issues with compliance.  
Other considerations should be whether the chart will be a paper document or electronic record, as well as who will have access to it and how easy it is to complete at the time fluid is entering or leaving the body. Paper documentation has reduced dramatically in hospital and healthcare environments, with many organisations moving to electronic record systems. This can pose more challenges to staff completing the charts, as access may be limited in some areas, either due to a lack of physical devices on which to input data, or connectivity issues. Community providers may be a separate organisation to the GP or acute areas and therefore may have a different method of recording, that again may be paper or electronic. The different provider systems may not interface with other providers, leaving gaps in knowledge or records. Leaving documentation in patients’ homes can cause issues with clinical governance and confidentiality, which clinicians should consider when determining what type of documentation to use.
Digital diaries are varied, and some may have a cost attached to their use. In the author’s clinical experience, they are useful in a community setting as they can be managed by the patient with a level of discretion. However, limitations can include a lack of detail of types of drinks, bowel action and other pertinent information, such as a comparison of daytime and night-time activity, medication effect/timing, that may help with diagnosis and appropriate management. Physically measuring urine can also cause an issue as individuals need a receptacle to capture the urine and enable measurement, which is not always discreet (Williamson et al, 2019). 
Bowel function can have a significant impact on the efficacy of bladder emptying, so monitoring of bowel action should be an intrinsic part of assessment when someone is completing an intake/output chart. Assessment must include frequency of bowel action and type of stool passed. Patients’ perceptions of what a normal or constipated bowel entail are subjective and may differ from a healthcare professional’s perception (Woodward, 2012). Constipation can cause urine retention or increased frequency of micturition. Normal bowel habit is accepted as a maximum of three times a day or a minimum of three times a week (RCN, 2019), while stool type is usually described using the Bristol stool chart (Heaton and Lewis, 1997).  


Much of the literature around fluid balance suggests a lack of understanding and training as a key reason for poor data collection (Tang and Lee, 2010; Johnstone et al, 2015; McGloin, 2015). Any training should include anyone involved in administering fluids/serving drinks, as well as those responsible for recording output. This may mean a level of education for the individual patient who will be responsible for completing their own records. Mandatory training for all levels of healthcare professionals, including medical staff, with regular timely updates to ensure knowledge and understanding of fluid balance monitoring may show an improvement in the compliance and benefit of the documentation. 
Questions to ask:  
  • Can the patient access drinks when they want or are they reliant on someone else to supply them?  
  • Does the patient finish the whole drink or is it left to go to cold?  
  • Can they physically lift and hold the drinking vessel?  
  • Does it have to be water to drink, or can a choice be offered?  
  • How much does a cup/mug/glass actually hold?  
Awareness of the importance of hydration has become a popular project in some areas, with posters and roadshows evident in hospitals and care homes (NHS Improvement, 2019). 
Interpretation and reaction to the data needs to be evidenced, a suggestion that in acute or looked after areas (i.e. care home, nursing home or visiting carers to patient’s own home) fluid balance charts should form an integral part of handover may lead to an improvement in consistency (Tang and Lee, 2010; Johnstone et al, 2015; McGloin, 2015; Vincent and Mahenddran, 2015). Introducing the use of software and automated bladder diaries may improve ease of recording data and compliance, as well as aiding diagnostics (Williamson et al, 2019). Ensuring that the data captured is accurate, relevant and timely will also improve the efficacy of the charts (Daffurn et al, 1994; Vincent and Mahendiran, 2015).  


Fluid balance is an essential component of monitoring patients at various stages of their life in both acute and primary care settings. Charts may be completed by staff or individual patients, so a level of understanding of how to complete the documentation must be established. The chart should not be a sole indicator of health but form a part of more holistic clinical assessment using a variety of tools and measures to understand the patient’s status. Interpreting the data collected on an intake/output chart and acting appropriately in response to the findings involves the multidisciplinary team and the patient themselves. Consideration for the clinical justification for completing input/ output charts will reduce unnecessary recording and inappropriate interpretation of the data. 


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This piece was first published in the Journal of Community Nursing. To cite this article use: Holroyd S (2020) Frequency volume charts and fluid balance monitoring: getting it right. J Community Nurs 34(1): 55-58