Understanding the principles and aims of intravenous fluid therapy

Free Understanding the principles and aims of intravenous fluid therapy

Mags Guest Lecturer in Adult Nursing and Clinical Skills, University of Hull, Hull, England

Why you should read this article
  • To understand the mechanisms used by the body to maintain fluid balance

  • To recognise the principles involved in assessing a patient who may require intravenous fluid therapy

  • To count towards revalidation as part of your 35 hours of CPD, or you may wish to write a reflective account (UK readers)

  • To contribute towards your professional development and local registration renewal requirements (non-UK readers)

A balance between the volume of fluid taken in by the human body, and the volume of fluid excreted, is essential for life. Body fluid balance, which is maintained via various homeostatic mechanisms, can be disrupted by injury or disease. Prompt action is usually required to replenish fluid volumes and restore homeostasis, which is achieved via intravenous (IV) fluid therapy. Nurses will often encounter patients with a disrupted fluid balance, particularly in critical care. They will be involved in assessing patients’ fluid status and administering and monitoring therapy. Therefore, nurses have an important role in ensuring the safety and effectiveness of IV fluid therapy. This article provides an overview of the principles and aims of IV fluid therapy. It also explains the physiology of body fluid and mechanisms of fluid balance regulation, outlines the principles of patient assessment and indications for IV fluid therapy, and details its potential risks and complications.

Nursing Standard. doi: 10.7748/ns.2020.e11459

Peer review

This article has been subject to external double-blind peer review and checked for plagiarism using automated software



Conflict of interest

None declared

Guest M (2020) Understanding the principles and aims of intravenous fluid therapy. Nursing Standard. doi: 10.7748/ns.2020.e11459

Published online: 27 January 2020

Aims and intended learning outcomes

The aim of this article is to assist nurses in understanding how the human body maintains fluid balance, what may disrupt fluid balance, and how intravenous (IV) fluid therapy can restore this. After reading this article and completing the time out activities you should be able to:

  • Recognise the risks of inappropriate IV fluid therapy.

  • Explain fluid balance and the homeostatic mechanisms that regulate it.

  • Assess patients’ fluid status and their IV fluid therapy requirements.

  • Outline the two main types of IV fluids and their mechanisms of action.

  • Understand the risks and complications of IV fluid therapy.

Key points

  • The body maintains its fluid balance primarily through renal activity. A change in this balance affects circulating plasma levels and triggers compensatory mechanisms aimed at restoring fluid balance

  • The body’s fluid balance can be altered by disease and injury. Pathological causes of fluid loss include haemorrhage, dehydration, sepsis, burns, severe diarrhoea and vomiting, and excessive urination

  • Patients who may require intravenous (IV) fluid therapy to restore fluid balance should be first assessed using the ABCDE (airway, breathing, circulation, disability, exposure) approach

  • Assessing a patient’s fluid status comprises several elements, including National Early Warning Score 2, fluid input and output, and examining biochemical markers

  • The two types of IV fluids available are crystalloids and colloids; which type is used will depend on the clinical situation


IV fluid therapy is commonly used in clinical practice, notably in secondary care, but also in the pre-hospital setting (Seymour et al 2014) and in primary care (Payne 2019). In hospital, many adult inpatients require IV fluid therapy to correct their fluid and/or electrolyte balance or prevent it from deteriorating (National Institute for Health and Care Excellence (NICE) 2017). Therefore, IV fluid therapy is an integral component of nursing practice.

The Royal College of Nursing (RCN) (2016) standards for infusion therapy state that, depending on their scope of practice, the involvement of healthcare professionals may include patient care, care of the device that administers the fluids, procurement of consumables, implementation of quality or safety improvement initiatives, and research activities. Nurses may be tasked with assessing the need for IV fluids, monitoring their administration, inserting and managing peripheral or central vascular access devices, and taking all necessary infection prevention and control measures (Dougherty and Lister 2015). These tasks may be undertaken by various members of staff, including nurses, nursing associates and healthcare assistants, depending on their competencies and scope of practice (RCN 2016, Nursing and Midwifery Council (NMC) 2018). Nurses with non-medical prescribing qualifications may also prescribe IV fluids (NMC 2019).

It is estimated that as many as one in five patients receiving IV fluids and electrolytes experience complications or morbidity because of inappropriate administration, primarily as a result of prescribing errors and suboptimal recording and monitoring (NICE 2017). Reasons cited for these issues include a lack of knowledge around IV fluid therapy, a lack of relevant experience and a lack of specific staff training (NICE 2017). Inappropriate IV fluid therapy may cause medical issues such as tissue hypoperfusion (decreased blood flow to tissues) and oedema, which can increase morbidity, mortality and the length of hospital stay (Hoste et al 2014).

Healthcare professionals need to ensure patients receive the most appropriate infusion therapy (Hallam et al 2016), so it is essential that they have the knowledge and skills to undertake their role safely and effectively. NICE (2017) published a clinical guideline for IV fluid therapy in adults in hospital, as well as a guideline on recognising and responding to deterioration in acutely ill adults in hospital (NICE 2007).

Composition of fluid in the body

In an average male, 60% of body weight is fluid, while in an average female, 55% of body weight is fluid (Frost 2015). Body fluid comprises water and dissolved constituents such as electrolytes (Macintosh 2011). It is essential to life and has several crucial functions, including controlling temperature, removing waste products, maintaining acid-base balance, and delivering nutrients and diffused gases to cells (Baumberger-Henry 2007).

Body fluid is found within cells (intracellular compartment) and outside cells (extracellular compartment). Intracellular and extracellular fluid volumes are separated by the walls of cells and capillary vessels – thin semipermeable membranes through which fluid is continually passing (Watson 2018). Around two thirds of body fluid is intracellular and one third is extracellular (McGloin 2015).

The extracellular compartment divides into the interstitial compartment (space surrounding cells) and intravascular compartment (space within blood vessels). Intravascular body fluid is known as plasma. Plasma is the liquid component of blood, comprising 55% of its volume; blood cells are the solid component of blood, making up the other 45% (Watson 2018). In an adult, around 3L of extracellular fluid is plasma, which contributes to a total circulating blood volume of around 5L (McGloin 2015). The movement of fluid in and out of the intravascular space is regulated by the opposing forces of hydrostatic and osmotic pressure. The walls of capillary vessels are permeable to water and small ions, but impermeable to the large protein molecules found in plasma (Macintosh 2011).

Maintaining fluid balance

Fluid balance is the balance between the volume of fluid taken in and the volume of fluid excreted by the body. Maintaining fluid balance is a critical bodily function (Popkin et al 2010). In homeostasis (balanced state of body function), optimal hydration is achieved, since the volume of fluid taken in matches the volume of fluid excreted by the body (Marieb and Hoehn 2016).

Maintaining the body’s fluid balance is predominantly achieved via renal activity (McLafferty et al 2014). Fluid intake and urine output are the main mechanisms for maintaining fluid balance (Gouldon 2016). A drop in circulating plasma volume can affect bodily functions such as oxygen delivery to the tissues and cells, for example through blood loss. Such a change will trigger compensatory mechanisms aimed at re-establishing homeostasis.

One compensatory mechanism is that initiated by the renin-angiotensin-aldosterone system (RAAS), which has an important role in the body’s response to plasma volume changes. A fall in blood pressure triggers a sequential renal and neural and/or adrenergic response (Tait 2015). The kidneys secrete renin (a serine protease protein and enzyme) and release it into the blood. Renin activates the RAAS pathway, prompting the adrenal cortex to secrete the hormone aldosterone. Aldosterone causes the renal tubules to increase their reabsorption of sodium, which releases water back into the blood, thereby expanding plasma volume and increasing blood pressure. Aldosterone also has an important role in potassium regulation. When the levels of potassium in extracellular fluid increase, so do aldosterone levels, which causes additional potassium ions to be excreted via the kidneys in the urine. This contributes to maintaining electrolyte balance in the body (Marieb and Hoehn 2016).

Another compensatory mechanism is provided by the vasoconstricting action of angiotensin II. Renin secreted by the kidneys converts angiotensinogen to angiotensin I. Angiotensin I is subsequently converted to angiotensin II by angiotensin-converting enzyme (ACE) secreted by the vascular endothelium, particularly in the lungs. Angiotensin II is a potent vasoconstrictor and causes blood pressure to rise (Casey 2012).

Plasma volume is further regulated by the action of antidiuretic hormone (ADH), a small peptide hormone secreted by the posterior pituitary gland. When osmoreceptors and baroreceptors detect a decrease in osmolality and blood pressure, they trigger the release of ADH. ADH heightens the sensation of thirst, which prompts patients to increase their oral fluid intake, thereby increasing body fluid volume (Marieb and Hoehn 2016).

Alteration of fluid balance

Fluid loss from the body contributes to an altered fluid balance and can be categorised as sensible or insensible. Sensible fluid loss is readily measurable (Kear 2017), while insensible fluid loss is not. Box 1 provides examples of sensible and insensible fluid losses.

Box 1.

Examples of sensible and insensible fluid losses

Sensible fluid loss

  • Urination

  • Defaecation

  • Blood loss

  • Wound and gastric drainage

  • Vomiting

Insensible fluid loss

  • Perspiration

  • Breathing

(Adapted from Kear 2017)

Box 2.

Main sources of fluid input and output

Sources of fluid input

  • Oral and nasogastric feeds

  • Intravenous infusions and fluids

  • Subcutaneous and rectal infusions

Sources of fluid output

  • Urine

  • Faeces

  • Vomit

  • Leakage from drains and stomas

  • Aspirate from nasogastric tubes

(Adapted from Dougherty and Lister 2015)

Box 3.

Signs and symptoms of dehydration, fluid overload and speed shock


  • Weight loss

  • Thirst

  • Irritability, restlessness and possible confusion

  • Diminished skin turgor

  • Dry mouth and furred tongue

  • Negative fluid balance (decreased fluid input compared with output)

Fluid overload

  • Weight gain

  • Positive fluid balance (decrease in fluid output compared with input)

  • Bounding pulse, indicating a high cardiac output

  • Raised central venous pressure

  • Peripheral oedema

  • Hoarse voice

  • Dyspnoea, cyanosis and coughing because of pulmonary oedema

Speed shock

  • Flushed face

  • Headache and dizziness

  • Chest congestion secondary to fluid accumulation

  • Tachycardia and fall in blood pressure

  • Syncope

  • Shock

  • Cardiovascular collapse

(Adapted from Weinstein and Hagle 2014)

The body’s fluid balance can be altered by disease and injury (Frost 2015). Pathological causes of fluid loss include haemorrhage, dehydration, sepsis, burns, severe diarrhoea and vomiting, and excessive urination (Gouldon 2016). In a healthy person, the body’s compensatory mechanisms described in the previous section will be effective in maintaining fluid balance; however, in ill health, if lost fluid is not replaced, these mechanisms will eventually fail (Dougherty and Lister 2015).

When blood is lost from the intravascular compartment – for example, through haemorrhage – the body compensates by drawing fluid from other areas. For every 1L of blood lost, within ten minutes, 600mL of fluid will move from the cellular and interstitial spaces into the intravascular space. This is known as internal transfusion (Gouldon 2016). However, failure to replace the lost fluid will eventually lead to cellular and organ dysfunction, which may ultimately result in organ failure and death (Goldstein 2014). Therefore, it is vital to restore fluid balance by replacing lost fluid.

A decrease in volume of circulating plasma in the body is known as hypovolaemia. Shock is a state of impaired delivery of oxygen to, or use of oxygen by, the cells (Adam et al 2017). Hypovolaemic shock occurs as a result of a loss of blood, plasma or extracellular fluid (Tait 2015). It requires the re-establishing of fluid balance and replenishing of circulating plasma volume to restore tissue perfusion and oxygen delivery (Macintosh 2011).

Time out 1

Reflect on a patient you have cared for with hypovolaemia. What methods did you use to assess the patient? What features were present that could have explained the fluid imbalance? What had caused hypovolaemia?

Assessment of fluid status

In its guideline on deterioration in acutely ill adults in hospital, NICE (2007) recommends monitoring all patients using physiological track-and-trigger systems. One such system is the National Early Warning Score 2 (NEWS2) (Royal College of Physicians (RCP) 2017), which uses six parameters: respiratory rate, oxygen saturation, temperature, systolic blood pressure, pulse rate and level of consciousness. It also incorporates new-onset confusion, emphasises the importance of considering serious sepsis in patients with known or suspected infection, and features a dedicated section for patients with hypercapnic respiratory failure in whom oxygen saturations of 88-92% are clinically recommended (RCP 2017). However, one limitation of NEWS2 is that urine output does not contribute to the scoring (Grant 2018).

Patients who may require IV fluid therapy should be carefully and comprehensively assessed. The ABCDE (airway, breathing, circulation, disability, exposure) approach (Resuscitation Council (UK) (RCUK) 2019) provides a systematic approach to the assessment of deteriorating patients (Smith and Bowden 2017). Patient assessment using the ABCDE approach ensures that vital signs are investigated in a logical sequence and that any life-threatening issues are prioritised. Once an initial assessment has been completed, regular re-assessments should be undertaken (RCUK 2019).

The clinical assessment of a patient’s fluid status comprises several elements (Scales and Pilsworth 2008), including:

  • Recording vital signs and NEWS2.

  • Monitoring fluid input and output.

  • Assessing and observing urine output.

  • Considering insensible fluid loss.

  • Measuring capillary refill time.

  • Examining biochemical markers.

  • Conducting bedside echocardiography.

Vital signs and National Early Warning Score 2

Recording the patient’s vital signs and NEWS2 will ascertain whether the patient has any signs and symptoms of hypovolaemia. Depending on the volume of fluid lost, patients with hypovolaemia may present with tachypnoea, tachycardia, hypotension, reduced oxygen saturations and oliguria (Tait 2015, Adam et al 2017). In patients who are young and healthy, compensation mechanisms for the initial fluid loss may delay the appearance of signs and symptoms until hypovolaemia has progressed. Indicators that a patient may require urgent fluid resuscitation include (NICE 2017):

  • Systolic blood pressure <100mmHg.

  • Heart rate >90 beats per minute.

  • Capillary refill time >2 seconds or peripheries cold to touch.

  • Respiratory rate >20 breaths per minute.

  • NEWS2 score ≥5.

  • Passive leg raising test suggests fluid responsiveness.

Time out 2

In your clinical area, locate and study a completed patient fluid balance chart. Has it been completed correctly? If not, what factors may explain why the chart was incomplete or not completed correctly? What could be done to improve fluid chart completion?

Fluid input and output

Monitoring fluid input and output, usually over a 24-hour period (Jevon et al 2012), is essential in determining whether the patient is adequately hydrated (Scales and Pilsworth 2008). Box 2 lists the main sources of fluid input and output that need to be recorded on the patient’s fluid chart. Fluid charts must be accurately completed, but there is evidence suggesting that this is not always the case. Vincent and Mahendiran (2015) conducted a project to improve the quality of fluid balance monitoring on the respiratory ward of one large district general hospital. Their baseline data showed that, among patients who were having their fluid input and output monitored, the average chart completion rate was 50%, the average chart accuracy was 41%, and monitoring was clinically indicated in 53% of patients.

Urine output

Assessing and observing urine output will assist in gauging the patient’s fluid status. In an adult, the minimum acceptable volume of urine is 0.5mL/kg/hr (Adam et al 2017). In hypovolaemic states, blood flow is prioritised to the heart, brain and lungs; a normal urine output; therefore, indicates adequate renal blood flow and thus adequate vital organ perfusion.

Urine should be a pale straw colour, but in patients who are fluid depleted, it will be increasingly concentrated and therefore darker (Scales and Pilsworth 2008).

Insensible fluid loss

While it is not readily measurable, the approximate volume of insensible fluid loss in adults is 650mL/day (Boron and Boulpaep 2016). It is important to be aware that factors such as pyrexia and increased respiratory rate can increase insensible fluid loss.

Capillary refill time

Capillary refill time is measured by applying pressure on a fingertip on an arm that has been raised to the level of the heart for five seconds, causing the blood to withdraw and the skin to turn pale, and observing how long it takes for the skin to regain its normal colour. A capillary refill time >2 seconds may indicate hypovolaemia (Jackson 2011). However, the use of skin colour as a diagnostic marker is not necessarily accurate and may be misleading in certain patient groups; for example, in patients with sepsis the inflammatory response causes peripheral vasodilation (Jackson 2011).

Biochemical markers

Patients who are dehydrated may present with raised levels of urea, creatinine, lactate, haematocrit and haemoglobin (Frost 2015), so biochemical markers should be examined. Laboratory investigations should include full blood count and urea, creatinine and electrolytes (NICE 2017).

Bedside echocardiography

Bedside echocardiography is increasingly used to determine patients’ fluid needs and evaluate the effects of IV fluid therapy. This technique has many benefits, including provision of real-time data and portability of the device used, and is safe and non-invasive (Casaroto et al 2015).

Time out 3

View the four algorithms provided by NICE (2016) on IV fluid therapy:

www.nice.org.uk/guidance/cg174/resources/intravenous-fluid-therapy-in-adults-in-hospital-algorithm-poster-set-191627821. Familiarise yourself with these algorithms and relate them to your practice

Intravenous fluid therapy

In IV fluid therapy, a solution, medicine, blood or blood product is infused directly into a vein (Perry et al 2017), either to maintain fluid balance when oral or enteral intake is inadequate, or to replace lost fluid. Using the IV route is an effective way of administering fluids to patients who are unable to meet their fluid intake requirements orally (Rees Doyle and McCutcheon 2015) or in whom the enteral route is not feasible. Using the IV route is also a rapid and effective method of administering fluids or medicines in emergency situations. Therefore, fluid resuscitation is one of the most common interventions in patients with hypovolaemia (Walter 2016) and is one of the most important strategies in the early management of patients who are critically ill (Rhodes et al 2016). For patients presenting with major haemorrhage secondary to trauma, fluid therapy using an isotonic crystalloid solution should be initiated in patients with hypotension (Spahn et al 2019).

The NICE (2017) guideline Intravenous Fluid Therapy in Adults in Hospital provides comprehensive guidance regarding indications and differentiating between ‘bolus’ and ‘maintenance’ regimens. A bolus regimen is used in patients who require IV fluid resuscitation, while a maintenance regimen is for patients who require routine maintenance (NICE 2017). IV fluid therapy should be based on five principles, known as the ‘five Rs’ (NICE 2017):

  • Resuscitation – urgent fluid resuscitation may be required following haemorrhage, infection, trauma or burns (Lewis et al 2018).

  • Routine maintenance – routine maintenance of fluid balance may be required, for example in patients who are unable to meet their fluid requirements through the oral or enteral route but are otherwise well in terms of fluid and electrolyte balance and handling. This includes patients who have had a stroke that has caused dysphasia, patients who are nil by mouth before surgery and patients with gastrointestinal obstruction. Once patients have regained the ability to meet their fluid requirements via the oral or enteral route, IV fluid therapy should be discontinued as soon as possible (Powell-Tuck et al 2011).

  • Redistribution – urgent IV fluid therapy may be required for redistribution purposes in patients experiencing disorders that affect the distribution of fluid in the body, such as sepsis and anaphylaxis. In sepsis, the inflammatory response causes vasodilation and fluid leak from the capillaries, and therefore causes an increase in vascular space that can lead to hypovolaemia (Adam et al 2017).

  • Replacement – replacement IV fluids may be required to treat existing deficits or ongoing external losses, usually from the gastrointestinal or urinary tract; for example, in patients with gastroenteritis or diabetic ketoacidosis (Finfer et al 2018).

  • Reassessment – frequent reassessment of patients’ response to, and ongoing need for, IV fluid therapy is essential (Hoste et al 2014). NICE (2017) provides detailed guidance on the frequency of re-assessment.

Time out 4

Referring to national guidelines and local policy as well as this article, prepare a short oral presentation for junior nurses on the various types of IV fluids and what differentiates them

Types of intravenous fluid

There are two main types of IV fluids, crystalloids and colloids, which both act as plasma volume expanders. Understanding their nature and composition will assist healthcare professionals in selecting the most appropriate fluid, which will prevent complications and improve patient outcomes (McClelland 2014). The choice of IV fluid directly affects fluid distribution in the body. All IV fluid initially enters the intravascular compartment; however, how much of it remains in the intravascular compartment and how much passes into the interstitial and intracellular compartments largely depends on which fluid is administered (Macintosh 2011).


Crystalloid solutions contain low-molecular-weight salts or sugars, which dissolve in water and freely pass between the intravascular space and the interstitial and intracellular spaces (Powell-Tuck et al 2011). A crystalloid solution temporarily replaces fluid lost in the intravascular space, but within hours of infusion, most of it will have passed into the interstitial and intracellular spaces. For every 1L of 0.9% sodium chloride (normal saline) infused, 750mL (75%) leaves the intravascular space and enters the interstitial and intracellular spaces (Gouldon 2016). Crystalloids effectively replace lost intracellular and interstitial fluid. They also increase blood volume and blood pressure, but larger volumes will be necessary to achieve this compared with a colloid solution.

Crystalloid solutions include 0.9% sodium chloride, Ringer’s lactate and 5% dextrose (Frost 2015). The most commonly used crystalloid worldwide is 0.9% sodium chloride (Walter 2016). Balanced crystalloids such as Hartmann’s solution are also widely used (Semler and Kellum 2019) and there has been an increase in the use of crystalloids mixing low-concentration sodium and dextrose for maintenance purposes, particularly in critical care (Hoorn 2017).

The benefits of crystalloids include their low cost and the fact that they have relatively few side effects. However, as they easily travel into the interstitial and intracellular spaces, they may cause oedema (Coppola et al 2014). Furthermore, the overuse of crystalloids containing sodium chloride may cause hyperchloraemic acidosis (Hoorn 2017).


Colloids contain larger molecules than crystalloids. These molecules are unable to cross capillary membranes, so colloid solutions largely remain in the intravascular space (Macintosh 2011). As a consequence, smaller amounts of colloids are required to replenish intravascular fluid volume compared with crystalloids, but colloids are not effective in replacing lost intercellular and interstitial fluid.

Colloids include gelatins, dextrans and hydroxyethyl starch (HES). Compared with crystalloids, colloids are associated with an increased risk of complications – including anaphylaxis, renal failure and coagulopathy – and are more expensive (Frost 2015). In 2014, the licence to produce HES was suspended in the UK because of evidence suggesting that the risks of its administration outweighed the benefits (Frost 2015). Following a review by the European Medicines Agency, HES remains licensed, but its use has been reduced (Cohen 2018).

Crystalloids versus colloids

There has been considerable debate about which IV fluid to use, particularly in patients with serious illness or injury, and there is wide variation in practice (NICE 2017). Numerous studies, and several systematic reviews of the evidence, have been conducted to explore the relative risks and benefits of crystalloids and colloids. A Cochrane review by Perel et al (2013) found no evidence that resuscitation with colloids reduced the risk of death in patients with trauma, burns or surgery compared with crystalloids. They questioned whether the use of colloids was justified considering that they are not associated with an improvement in survival, and are considerably more expensive than crystalloids (Perel et al 2013). In their update of this Cochrane review, Lewis et al (2018) concluded that there is no apparent benefit of using a colloid rather than a crystalloid for fluid resuscitation in patients who are critically ill.

NICE (2017) recommends that crystalloid solutions should initially be used for IV fluid therapy. However, they also explain that, after initial therapy, specific situations and conditions will require specific fluids. Certain types of fluids are more appropriate than others in certain circumstances. For example, human albumin solutions should only be considered for use in patients with severe sepsis who require IV fluid resuscitation (NICE 2017). For patients who are actively bleeding, it is recommended that crystalloids are not used and that a ratio of one unit of plasma to one unit of red cells is used to replace fluid volume (NICE 2019).

NICE (2017) provides detailed guidance on which IV fluid to use in which clinical situation, as well as advice on volumes, dosages, timings and duration of therapy.

Risks and complications

Since nurses have a central role in managing patients receiving IV fluid therapy, they need to be aware of its potential risks and complications. A National Confidential Enquiry into Patient Outcome and Death (2011) report identified that patients who were given excessive or insufficient fluids after surgery were at an increased risk of death. Under-infusion or over-infusion of IV fluids can have serious consequences for patients. For example, under-infusion may lead to dehydration while over-infusion may lead to fluid overload (hypervolaemia). Furthermore, the rapid administration of large volumes of fluid may lead to speed shock (Perucca 2010), a systemic reaction that can occur when a substance foreign to the body is introduced too quickly into the circulation (Weinstein and Hagle 2014). Box 3 details the signs and symptoms of some of the complications that can arise from under-infusion and over-infusion of fluids.

Other risks relating to IV fluid therapy include the risk of infection from indwelling catheters and the risk of injury from extravasation. Extravasation is the inadvertent administration of vesicant medication or solution into the surrounding subcutaneous or subdermal tissue instead of the intended vascular pathway (RCN 2016). Therefore, nurses have an essential role in maintaining cleanliness during catheter and dressing changes, monitoring infusion sites, and assessing patients for signs and symptoms of infection.


Fluid balance is regulated by homeostatic mechanisms primarily involving the renal, neurological and cardiac systems. Fluid balance may be disrupted by injury or disease, in the presence of which the body’s compensatory mechanisms will no longer be effective and fluid balance will need to be restored via IV fluid therapy. Suboptimal assessment, incorrect prescribing, over-infusion or under-infusion and inadequate monitoring may affect patients’ outcomes, potentially causing further deterioration and death. Nurses need to have the knowledge and skills required to: recognise the signs and symptoms of fluid loss and hypovolaemia; assess and monitor patients’ fluid balance; manage IV fluid administration and vascular access devices; and potentially prescribe IV fluids.

Time out 5

Consider how the safe administration of IV fluid therapy relates to The Code: Professional Standards of Practice and Behaviour for Nurses, Midwives and Nursing Associates (NMC 2018) or, for non-UK readers, the requirements of your regulatory body

Time out 6

Now that you have completed the article, reflect on your practice in this area and consider writing a reflective account: rcni.com/reflective-account


  1. Adam S, Osborne S, Welch J (2017) (Eds) Critical Care Nursing – Science and Practice. Third edition. Oxford University Press, Oxford.
  2. Baumberger-Henry M (2007) Quick Look Nursing – Fluids and Electrolytes. Second edition. Jones and Bartlett, London.
  3. Boron WF, Boulpaep EL (2016) Medical Physiology – A Cellular and Molecular Approach. Third edition. Saunders Elsevier, Philadelphia PA.
  4. Casaroto E, Mohovic T, Pinto LM et al (2015) Bedside echocardiography in critically ill patients. Einstein. 13, 4, 644-646. doi: 10.1590/S1679-45082015MD3271
  5. Casey G (2012) Kidney care and renal disease. Nursing New Zealand. 18, 4, 20-24.
  6. Cohen D (2018) EMA calls for hydroxyethyl starch solutions to be taken off market. BMJ. 360, k225. doi: 10.1136/bmj.k225
  7. Coppola S, Froio S, Chiumello D (2014) Fluid resuscitation in trauma patients: what should we know? Current Opinion in Critical Care. 20, 4, 444‐450. doi: 10.1097/MCC.0000000000000115
  8. Dougherty L, Lister S (2015) The Royal Marsden Manual of Clinical Nursing Procedures. Ninth edition. Wiley-Blackwell, Chichester.
  9. Finfer S, Myburgh J, Bellomo R (2018) Intravenous fluid therapy in critically ill adults. Nature Reviews Nephrology. 14, 9, 541-557. doi: 10.1038/s41581-018-0044-0
  10. Frost P (2015) Intravenous fluid therapy in adult inpatients. BMJ. 350, g7620. doi: 10.1136/bmj.g7620
  11. Goldstein SL (2014) Fluid management in acute kidney injury. Journal of Intensive Care Medicine. 29, 4, 183-189. doi: 10.1177/0885066612465816
  12. Gouldon I (2016) Shock presentation. In Clarke D, Ketchell A (Eds) Nursing the Acutely Ill Adult – Priorities in Assessment and Management. Second edition. Palgrave Macmillan, Basingstoke, 45-70.
  13. Grant S (2018 ) Limitations of track and trigger systems and the National Early Warning Score. Part 1: areas of contention. British Journal of Nursing. 27, 11, 624-631. doi: 10.12968/bjon.2018.27.11.624
  14. Hallam C, Weston V, Denton A et al (2016) Development of the UK Vessel Health and Preservation (VHP) framework: a multi-organisational collaborative. Journal of Infection Prevention. 17, 2, 65-72. doi: 10.1177/1757177415624752
  15. Hoorn E (2017) Intravenous fluids: balancing solutions. Journal of Nephrology. 30, 4, 485-492. doi: 10.1007/s40620-016-0363-9
  16. Hoste EA, Maitland K, Brudney CS et al (2014) Four phases of intravenous fluid therapy: a conceptual model. British Journal of Anaesthesia. 113, 5, 740-747. doi: 10.1093/bja/aeu300
  17. Jackson J (2011) Principles of assessment. In Clarke D, Ketchell A (Eds) Nursing the Acutely Ill Adult – Priorities in Assessment and Management. Palgrave Macmillan, Basingstoke, 14-38.
  18. Jevon P, Ewens B, Singh Pooni J (2012) Monitoring the Critically Ill Patient – Essential Clinical Skills for Nurses. Third edition. Wiley-Blackwell, Chichester.
  19. Kear TM (2017 ) Fluid and electrolyte management across the age continuum. Nephrology Nursing Journal. 44, 6, 491-496.
  20. Lewis SR, Pritchard MW, Evans DJ et al (2018) Colloids versus crystalloids for fluid resuscitation in critically ill people. Cochrane Database of Systematic Reviews. Issue 8. CD000567. doi: 10.1002/14651858.CD000567.pub7
  21. Macintosh M (2011) Cardiovascular assessment and management. In Macintosh M, Moore T (Eds) Caring for the Seriously Ill Patient. Second edition. Hodder Arnold, London, 1-42.
  22. Marieb EN, Hoehn K (2016) Human Anatomy and Physiology. Tenth edition. Pearson, Harlow.
  23. McClelland M (2014 ) IV therapies for patients with fluid and electrolyte imbalances. Med-Surg Nursing. 23, 5, Suppl 4-8.
  24. McGloin S (2015 ) The ins and outs of fluid balance in the acutely ill patient. British Journal of Nursing. 24, 1, 14-18. doi: 10.12968/bjon.2015.24.1.14
  25. McLafferty E, Johnstone C, Hendry C et al (2014) Fluid and electrolyte balance. Nursing Standard. 28, 29, 42-49. doi: 10.7748/ns2014.
  26. National Confidential Enquiry into Patient Outcome and Death (2011) Knowing the Risk: A Review of the Peri-Operative Care of Surgical Patients. http://www.ncepod.org.uk/2011report2/downloads/POC_fullreport.pdf (Last accessed: 19 December 2019.)
  27. National Institute for Health and Care Excellence (2007) Acutely Ill Adults in Hospital: Recognising and Responding to Deterioration. Clinical guideline No. 50. NICE, London.
  28. National Institute for Health and Care Excellence (2016) Algorithms for IV Fluid Therapy in Adults. http://www.nice.org.uk/guidance/cg174/resources/intravenous-fluid-therapy-in-adults-in-hospital-algorithm-poster-set-191627821 (Last accessed: 19 December 2019.)
  29. National Institute for Health and Care Excellence (2017) Intravenous Fluid Therapy in Adults in Hospital. Clinical guideline No. 174. NICE, London.
  30. National Institute for Health and Care Excellence (2019) Major Haemorrhaging in Hospital. http://pathways.nice.org.uk/pathways/trauma#path=view%3A/pathways/trauma/major-haemorrhaging-in-hospital.xml&content=view-index (Last accessed: 19 December 2019.)
  31. Nursing and Midwifery Council (2018) The Code: Professional Standards of Practice and Behaviour for Nurses, Midwives and Nursing Associates. NMC, London.
  32. Nursing and Midwifery Council (2019) Realising Professionalism: Standards for Education and Training. Standards for Prescribing Programmes. http://www.nmc.org.uk/standards/standards-for-post-registration/standards-for-prescribers/standards-for-prescribing-programmes (Last accessed: 19 December 2019.)
  33. Payne D (2019 ) Administering intravenous therapy in patients’ homes. British Journal of Community Nursing. 24, 2, 67-71. doi: 10.12968/bjcn.2019.24.2.67
  34. Perel P, Roberts I, Ker K (2013) Colloids versus crystalloids for fluid resuscitation in critically ill patients. Cochrane Database of Systematic Reviews. Issue 2. CD000567. doi: 10.1002/14651858.CD000567.pub6
  35. Perry A, Potter P, Ostendorf W (2017) Clinical Nursing Skills and Techniques. Ninth edition. Elsevier-Mosby, St Louis MO.
  36. Perucca R (2010) Peripheral venous access devices. In Alexander M, Corrigan A, Gorski L et al (Eds) Infusion Nursing: An Evidence-Based Approach. Third Edition. Saunders Elsevier, St Louis MO, 456-479.
  37. Popkin BM, D’Anci KE, Rosenberg IH (2010 ) Water, hydration, and health. Nutrition Reviews. 68, 8, 439-458. doi: 10.1111/j.1753-4887.2010.00304.x
  38. Powell-Tuck J, Gosling P, Lobo DN et al (2011) British Consensus Guidelines on Intravenous Fluid Therapy for Adult Surgical Patients (GIFTASUP). http://www.bapen.org.uk/pdfs/bapen_pubs/giftasup.pdf (Last accessed: 19 December 2019.)
  39. Rees Doyle G, McCutcheon JA (2015) Clinical Procedures for Safer Patient Care. BC Open Textbook Project, Minneapolis MN.
  40. Resuscitation Council (UK) (2019) Guidelines and Guidance: The ABCDE Approach. http://www.resus.org.uk/resuscitation-guidelines/abcde-approach (Last accessed: 19 December 2019.)
  41. Rhodes A, Evans LE, Alhazzani W et al (2016) Surviving sepsis campaign: international guidelines for management of sepsis and septic shock: 2016. Critical Care Medicine. 45, 3, 486‐552. doi: 10.1097/CCM.0000000000002255
  42. Royal College of Nursing (2016) Standards for Infusion Therapy: Fourth Edition. http://www.rcn.org.uk/-/media/royal-college-of-nursing/documents/publications/2016/december/005704.pdf (Last accessed: 19 December 2019.)
  43. Royal College of Physicians (2017) National Early Warning Score (NEWS) 2. http://www.rcplondon.ac.uk/projects/outputs/national-early-warning-score-news-2 (Last accessed: 19 December 2019.)
  44. Scales K, Pilsworth J (2008) The importance of fluid balance in clinical practice. Nursing Standard, 22, 47, 50-57. doi: 10.7748/ns2008.
  45. Semler MW, Kellum JA (2019) Balanced crystalloid solutions. American Journal of Respiratory Critical Care Medicine. 199, 8, 952-960. doi: 10.1164/rccm.201809-1677CI
  46. Seymour CW, Cooke CR, Heckbert SR et al (2014) Prehospital intravenous access and fluid resuscitation in severe sepsis: an observational cohort study. Critical Care. 18, 5, 533. doi: 10.1186/s13054-014-0533-x
  47. Smith D, Bowden T (2017 ) Using the ABCDE approach to assess the deteriorating patient. Nursing Standard. 32, 14, 51-63. doi: 10.7748/ns.2017.e11030
  48. Spahn DR, Bouillon B, Cerny V et al (2019) The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition . Critical Care. 23, 98, 1-74. doi: 10.1186/s13054-019-2347-3
  49. Tait D (2015) The patient in shock. In Tait D, James J, Williams C et al (Eds) Acute and Critical Care in Adult Nursing. Second edition. Sage, London, 147-173.
  50. Vincent M, Mahendiran T (2015) Improvement of fluid balance monitoring through education and rationalisation . BMJ Quality Improvement Reports. 4, 1. doi: 10.1136/bmjquality.u209885.w4087
  51. Walter E (2016) IV crystalloids: is one better than the other? Critical Care Alert. 23, 11, 81-84.
  52. Watson R (2018) Anatomy and Physiology for Nurses. 14th edition. Baillière Tindall, London.
  53. Weinstein SM, Hagle ME (2014) Plumer’s Principles and Practice of Infusion Therapy. Ninth edition. Lippincott Williams & Wilkins, Philadelphia PA.
Related articles

An overview of non-Hodgkin’s lymphoma
Non-Hodgkin’s lymphoma is a heterogeneous group of...

Reducing medication errors in nursing practice
Medication errors remain one of the most common causes of...

Myelodysplastic syndromes: update and nursing considerations
This article provides nurses with an update on diagnosis,...

Use of olaparib in BRCA mutation-positive ovarian cancer
Nurses should understand the role and purpose of the new...

Recognising and managing acute hyponatraemia
A significant amount of clinicians’ time is spent managing...