A Logical Prescription of Intravenous Fluids

Abstract

This chapter guides clinicians through the assessment and management of patients requiring intravenous (IV) fluids during hospitalization in the regular ward and ICU. It aims to aid in the determination of the patient’s actual fluid or volume status and guides the prescription and management of electrolyte replacement whilst avoiding potential harm to patients from fluid mismanagement leading to electrolyte disturbances, fluid accumulation, and organ impairment (or a combination). This is referred to as IV Fluid Stewardship, and it incorporates much of the National Institute for Health and Care Excellence (NICE) guidance published.

FormalPara IFA Commentary

Fluid prescribing has been shown in the UK to be associated with significant morbidity and mortality. It has been estimated that up to 20% of patients who receive intravenous fluids suffer iatrogenic harm as a result. It is therefore an area in which investing some effort in improvement is likely to prevent a great deal of patient harm. The National Institute for Health and Care Excellence (NICE) has published national guidance in the UK for intravenous fluid therapy in adults. These guidelines, issued in 2013, advised less use of 0.9% sodium chloride than current practice, provided a logical system for prescribing, and suggested further study of electrolyte abnormalities. Recently, Marcia McDougall and colleagues working in a district general hospital in Fife, Scotland, developed a local version of these guidelines and have implemented them over a number of years [1]. Their conclusions were that effective implementation required substantial time, effort, and resources. NICE suggestions of fluid types for maintenance appear appropriate, but prescribed volumes continue to require careful clinical judgement. A stepwise approach should therefore be undertaken:

• Establish a team and decide on its members.

• Perform baseline audits to assess the current situation within an establishment.

• Identify the drivers for change and any barriers to them. This needs to cover issues arising within medicine and nursing.

• Identify the target audience and establish the best ways to engage medical and nursing leaders in the need for change.

• Implementation of the guideline into practice.

• Assess the changes with quality improvement PDCA cycles, roll out new charts, plus additional material forwards (e.g. posters, learning aids).

• Keep the programme up-to-date and ensure it is maintained and monitored going forward.

This chapter outlines common problems with fluid administration, background physiology, volume assessment, prescribing, and troubleshooting along with how to put appropriate measures in place in a hospital setting.

The pitfalls and challenges of introducing large-scale changes such as the ones suggested in this chapter will need to be examined in the future. Suggestions should be made as to how clinicians may be able to effect sustainable change within this rewarding and immensely important area of health care.

FormalPara Learning Objectives

After reading this chapter, the reader will understand

• 1. How to assess patients requiring IV fluid therapy.

• 2. How to manage patients requiring IV fluid therapy.

• 3. How to assess the patient’s volume status and fluid responsiveness.

• 4. How to manage electrolyte disturbances.

• 5. How to avoid complications.

• 6. How to prescribe fluids appropriately.

FormalPara Case Vignette

A 42-year-old male, post-operative day 3 in the ICU after radical hemicolectomy and primary anastomosis for carcinoma of the ascending colon. The drain output in the last 24 h is serosanguinous. Nasogastric aspirate is 750 mL in the last 24 h. He is afebrile, haemodynamically stable, and his body weight is 81 kg (before surgery, 77 kg).

Laboratory investigation includes haemoglobin 8.1 gm%, platelets 99,000, sodium 131 meq/L, chloride 100 meq/L, potassium 3.1 meq/L, bicarbonate 26 mmol/L, serum creatinine 107 μmol/L.

Questions

• Q1. What information do you need to manage IV fluids for this patient?

• Q2. How will you write a prescription for IV fluid for this patient?

Introduction

This chapter guides clinicians through the assessment and management of patients requiring intravenous (IV) fluids. It aims to aid in determining the patient’s actual fluid or volume status and guides the appropriate prescription and management of electrolyte and fluid therapy to prevent complications like electrolyte disturbances, fluid accumulation, and organ failure or a combination. This is referred to as IV Fluid Stewardship, and it incorporates much of the National Institute for Health and Care Excellence (NICE) guidance published and the British Consensus Guidelines on Intravenous Fluid Therapy for Adult Surgical Patients (GIFTASUP) [2, 3].

Hereafter, we will set the stage for a conceptual framework for developing institutional programs and guidelines to enhance fluid stewardship (especially in the operating room (OR), emergency room (ER), and intensive care unit (ICU) environment), an activity that includes appropriate selection, indication, dosing, duration, de-escalation, and monitoring of fluid therapy. Analogous to the use of antibiotics, the multifaceted nature of fluid stewardship will need collaboration between different disciplines like emergency medicine, critical care, anaesthesiology, as well as general medicine, surgery, and clinical pharmacy [4].

Intravenous (IV) fluids are some of the most commonly prescribed day-to-day therapeutics [5, 6]. They should, however, be considered as any other drug, and they have their indications, contra-indications, benefits, risks, adverse side effects, and complications. Often, the task of IV fluid prescription is delegated to the most junior members of the team. Or even worse, in many circumstances, there is no IV fluid prescription available and the decision to start and choose the right fluid is left to the attending nurse. Evidence suggests that when available, these prescriptions are rarely ever done correctly despite the presence of clear guidelines (NICE CG174: NICE Intravenous Therapy in Adults in Hospital, https://www.nice.org.uk/guidance/cg174).

This is thought to be due to a lack of knowledge and experience, which often leads to confusion. Consequently, this puts many patients at increased risk of serious harm and may incur unnecessary costs.

It is therefore imperative to carefully assess individual patients, their fluid requirements, and the clinical picture (with comorbidities and complications), in order to tailor IV fluid plans safely. Ideally, fluids should be prescribed on the ward-round by the team who knows the patient and their history. Non-parent team prescriptions, particularly out-of-hours, require extra care, and should not be done as a duplication of the last prescription to save time. Clearly, there are emergent situations whereby fluids need to be prescribed outside of this policy. An introduction to fluid stewardship is discussed in Chap. 27.

The Problem

Previous retrospective reviews of prescriptions have identified poor control of the process. There were considerable variations in IV fluid prescriptions, none of which adhered to NICE guidelines. At times, some prescriptions were placing patients at increased risk of associated complications. The knowledge base among medical staff regarding IV fluids was extremely variable, sometimes poor, as shown by the results of the knowledge on different domains listed hereafter [7].

• Fluid volumes.

  • 84% had incorrect volumes prescribed for maintenance fluids.

• Electrolytes and glucose.

  • Patients received excessive amounts of sodium within their IV fluid prescriptions, yet minimal potassium.

  • Only 25% contained the correct amount of glucose.

• Production of a new IV fluid bundle led to significant improvements in the measured outcomes and balancing measures.

  • All patients had a documented review of both fluid status and balance.

  • The incidence of deranged urea and electrolytes (U&Es) decreased from 48% to 35%.

  • The incidence of acute kidney injury (AKI) decreased from 14% to 10%.

  • The average number of days between the latest U&Es and a fluid prescription decreased from 2.2 days to 1.0 day.

More recently, an online survey was conducted and shared with the participants of the ninth International Fluid Academy Days (IFAD) held in Valencia (Spain) at the end of October 2019. The same was conducted amongst delegates preparing for the first Virtual eIFAD (Nov 2020), assessing their views on fluid choices in their daily clinical practice [8]. The survey consisted of 57 multiple-choice or open questions, 26 covering knowledge of fluid management and stewardship. A total of 1045 surveys were received with respondents coming from 97 different countries. The interim results after 645 respondents were presented at the first virtual eIFAD meeting on 27 November 2020. A total of 862 (83.5%) of the respondents reported being qualified specialist (of which 431 (42%) were intensivists) and 131 were still in training. The years of experience ranged from 0 to 52 with a mean of 15 ± 10 years. The average score on the knowledge questions was 47 ± 14% (range 4–100). The most difficult questions were: “What is the most important clinical parameter to estimate volaemic status?” and “How much free sodium is there in 1 L of saline?” (Table 28.1). Intensivists had the best score 48.6 ± 13.8%, followed by anaesthetists with 45 0.8 ± 14.3%, internists 45.1 ± 16%, and emergency physicians 41.7 ± 10.9% (95% CI 37.8–48.2). About 26% of respondents reported having a hospital fluid guideline and 36% reported to have an ICU fluid guideline. Fluid balance was regularly measured by 88% of respondents and patients’ body weight by only 58% [9].

Table 28.1 Overview of knowledge questions with difficulty level and average scores

Application of these Clinical Guidelines

Target Group

• All critically ill and ICU patients are considered potential candidates for resuscitation fluids.

• Patients are considered for maintenance or replacement IV fluids:

  • Those with existing or developing deficits that cannot be compensated by oral intake.

  • When fluids are lost via drains or stomata, fistulas, fever, open wounds (including evaporation during surgery), polyuria (salt wasting nephropathy or diabetes insipidus).

• The overall aim is to match the amount of fluid and electrolytes as closely as possible, to the fluid that is needed or is being or has been lost, on a daily basis.

Exclusions

• Patients under the age of 16—need a consult by the paediatric team.

• Diabetes and especially diabetic ketoacidosis (DKA)—use current diabetes guidance or diabetic emergency guidance.

• Burns—existing burns calculations should be used.

• Obstetrics—need to discuss with the senior obstetric team for more complex patients.

• Head injury—avoid hypotonic fluids containing glucose and liaise with a neurotrauma centre.

• Renal/Liver patients—discuss with senior gastro/renal team.

• Elective and emergency theatre cases—managed by the anaesthetist caring for the patient in theatre. The relevance of this policy comes in post-operative ward management.

Professional Groups

This guideline is relevant to all doctors, physician associates, advanced nurse practitioners, and nurses working in all areas of the hospital, other than paediatrics.

Clarification of Terms

The used terms often cause confusion in clinicians. There is a plethora of different terms that are used interchangeably. A multidisciplinary consensus statement on dehydration: definitions, diagnostic methods and clinical implications published in 2019 has sought to clarify these terms (DOI: https://doi.org/10.1080/07853890.2019.1628352 or https://bit.ly/2RvAiEF) [10].

Dehydration

Hypertonic dehydration—water deficit causing hyperosmolality. Such a patient will have a high sodium. It results from inadequate water intake or increased losses (e.g. sweating). Intravascular volume is preserved while intracellular volume is reduced.

Isotonic dehydration—water and salt loss causing a deficit of extracellular fluid with normal osmolality. Haemoconcentration will be manifested by a high haemoglobin/haematocrit. Large volume GI losses from vomiting, NG-free drainage, diarrhoea, and large stoma output cause such fluid loss with relatively preserved sodium levels as GI fluid contains varying amounts of sodium. The two types of dehydration often co-exist (e.g. not drinking and vomiting).

Hypovolaemia is caused by loss of blood or ECF and specifically describes intravascular volume depletion.

Background Clinical Physiology

Patients are often given too much IV fluid—particularly non-physiological 0.9% sodium chloride). Once within the body, such sodium excesses are very difficult to remove and can result in harm. The cumulative sodium balance may be more important than the fluid balance per se, as even normal kidneys may take days, if not weeks, to get rid of the excess [11, 12].

There are extremes—increased fluid load can cause major electrolyte swings, whereas dehydration, can lead to poor organ perfusion. Sick patients (particularly those with systemic inflammatory response syndrome (SIRS) and those with sepsis), have “leaky” capillaries. This has been recently referred to as the globally increased permeability syndrome or “GIPS,” defined as the absence of a spontaneous transition from the Ebb to Flow phase of shock with a persistent positive cumulative fluid balance and new-onset organ dysfunction or failure [5, 6]. In this situation, even careful IV fluid administration can lead to fluid overload and resultant complications (pulmonary oedema, venous congestion, ileus, poor mobility following peripheral oedema, pressure sores, poor wound healing, and anastomotic breakdown). This is because the administered fluid escapes from the intravascular compartment, flooding the interstitial compartment, where it offers no physiological benefit.

These patients are sometimes incorrectly labelled as being hypovolaemic, when in fact they are vasodilated. We have a situation whereby excess administered fluid has escaped into another body compartment away from its beneficial site within the circulating volume (first space). After sensible fluid challenges and identification of “non-response,” these patients require early consideration of vasopressor therapy (i.e. noradrenaline) [13]. Therefore, in sepsis and states of critical illness, poor IV fluid prescribing practice can ultimately lead to morbidity, and even worse, mortality.

We often look at urine output as a marker of fluid requirement; however, patients who are unwell, have suffered trauma, or have undergone surgery often have a reduced urine output due to increased sodium retention (and thus water), by the kidneys. This is a natural stress response and is geared to hold on to intravascular volume to maintain vital organ perfusion during such stress states. Stress-induced (“inappropriate”) anti-diuretic hormone secretion, as well as intrinsic vasopressor hormone secretion, leads to a state of sodium and water retention and potassium loss in the urine. The patient becomes oedematous, hypokalaemic, and hypernatraemic over time, if left unchecked. Suppose normal saline has been given as a resuscitation fluid or maintenance fluid. In that case, a potential hyperchloraemic metabolic acidosis can ensue, on top of these other electrolyte imbalances, further leading to AKI.

The arterioles in the kidneys auto-regulate blood flow above a minimum mean pressure (around 60 mmHg). If blood pressure is not very low, then IV fluids can be of no benefit to renal perfusion. They may even lead to high venous pressures which will reduce perfusion (venous congestion).

No patient should suffer the effects of cellular dysfunction and ultimately multi-organ dysfunction, as a result of excessive and/or inappropriate IV fluid prescription and provision. Armed with an understanding of fluid physiology, one can see why oliguria is a poor marker of fluid requirement. Physiological oral fluids should always be the first line unless circumstances absolutely disallow it.

The best fluid may be the one that has not been given … (unnecessarily) [14].

In the next paragraphs, we will list some practical considerations to IV fluid prescription [15].

Considerations Prior to All IV Fluid Prescriptions

Assessment

• Patient’s fluid status (hypo/eu/hypervolaemia)—Assess at the time of fluid prescription using: clinical judgement, presence of oedema, vital signs, and fluid balance including urine output.

• Patient’s weight—Within the last 24 h (ICU) or 3 days (regular ward).

• Patient’s Urea and Electrolytes—Within the last 24 h assessed as part of every ward review.

• Patient’s fluid balance charts (input and output)—Over the last 24 h.

General Principles

Prescription safety can be summarised by the “4 D’s” principle [14]:

• Drug—which fluid [type, colloid vs crystalloid, isotonic vs hypotonic vs hypertonic, balanced or buffered vs unbalanced (saline)].

• Dose—calculate how much and how fast (rate) to give via a pump.

• Duration—duration of the IV fluid therapy.

• De-escalation—taper or stop IV fluids as soon as possible or start fluid removal (de-resuscitation).

Give the Right fluid in the Right Dose to the Right patient at the Right time.

Step 1: Assess Fluid Status

• Basic history and examination of the patient will give pointers as to what their volaemic status is (see Table 28.2).

• The best fluid to give in case of hypovolaemia is physiological fluid, i.e. oral fluid. Always consider this first.

Table 28.2 Volaemic Status assessment [16]. BP blood pressure, HR heart rate, JVP jugular venous pressure, MAP mean arterial pressure, PLR passive leg raising test, RR respiratory rate UO urine output

• In the case of euvolemia, no fluids need to be given except if there are expected losses that cannot be compensated orally, the patient cannot meet basic needs, or electrolyte disturbances are present requiring IV correction and oral supplementation is not possible.

• In the case of hypervolaemia, the first step is to check proactively whether the patient is receiving an IV infusion that must be stopped. In the case of the GIPS, defined as fluid accumulation with an impact on organ function, fluids must be removed actively using diuretics or ultrafiltration (see Chap. 25).

• Advanced users may utilize non-invasive cardiac output monitoring, transpulmonary thermodilution with volumetric preload indicators, or point-of-care ultrasound to assess the fluid status of patients. This is out of the scope of this guideline.

Step 2: Check Body Weight

• It is important to record and measure (do not guess) patient weight on admission and at least once or twice weekly.

• Weight gain over a short period of time during hospitalization is usually due to excessive IV fluid loading (as muscles and fat tissue take more time to build up).

• Assess for fluid overload (or better accumulation).

  • Dividing the cumulative fluid balance in litres by the patient’s baseline body weight x 100% defines the percentage of fluid accumulation.

  • Fluid overload is defined by a cut-off value of 10% of fluid accumulation, and this is associated with worse outcomes.

• Check body and fluid composition with bio-electrical impedance analysis (when available) to obtain TBW, ECW/ICW ratio and volume excess.

Step 3: Check U&E Levels in the Last 24 h

• Patients who are being considered for IV fluid therapy should have documented U&E results within the last 24 h. If not, levels should be taken as soon as possible.

• The presence of acute kidney injury (AKI) using KDIGO criteria should be checked.

• This is to gauge both the effects of the exogenous fluid over time on the patient’s electrolyte levels and to ensure inappropriate fluid is not administered to them (potassium-containing fluid if already hyperkalaemic or sodium-containing fluid if hypernatraemic, etc.).

Step 4: Calculate Fluid Balance in the Last 24 h

• Fluid balance is key. All patients should have accurate input/output charting. Clearly, it is more challenging to do this precisely in those who are not catheterized.

• Review recent history for:

  • Losses:

    • Fasting, operations, sepsis, excessive sweating in febrile states, diarrhoea, and vomiting

      • Upper G.I losses in excess, i.e. vomiting, tend to lead to states of alkalosis, potential electrolyte disturbance, and “true” dehydration.

      • Lower G.I losses in excess i.e. diarrhoea, tend to lead to states of acidosis, potential electrolyte disturbance including hypokalaemia, and true dehydration.

  • Gains:

    • Fluid overload states (oedema and excessive positive balance).

• Assessment for normal intake.

  • Is the patient eating and drinking adequately? The best fluid is physiological fluid, i.e. oral intake.

  • If patients are not nil by mouth and are not suffering from excessive losses, requests to prescribe IV fluids should be challenged.

  • Fluids are drugs, and they should be held in equal esteem.

  • All fluids administered need to be considered: oral, IV, catheter flush (A-line).

• Check recorded losses.

  • Has the patient lost fluid, are they currently losing fluid, or are they not drinking appropriately? Examples include stoma output, vomiting, diarrhoea.

  • Think also of insensible fluid loss (evaporation of water along the skin and respiratory tract). This loss is higher in patients with fever (approximately 10 mL/kg/day) than in ventilated patients with active or passive humidification (approximately 5 mL/kg/day).

Consider adding excessive losses to your calculated daily maintenance fluid. Amount lost in 24 h divided by 24 to give the amount to add to maintenance per hour.

Step 5: Prescribe the Appropriate IV Fluid on a Daily Basis

The IV fluid prescription is adapted to the patient’s basal and current needs, deficiencies, as well as any fluid/electrolyte losses. Check for electrolyte disturbances, glycaemia, heart function, liver, and kidney function. Always document the type and indication of the IV infusion in patient’s medical records. Make a fluid prescription every 24 h and adapt it according to the patient’s needs. Patients should have an IV fluid management plan, including a fluid and electrolyte prescription for the proceeding 24 h. The prescription for a maintenance IV fluid should only change after a clinical exam, a change in dietary intake or after the evaluation of laboratory results. The following information should be included in the IV fluid prescription: the type of fluid, the rate and volume of fluid infusion, the objective, and the safety limits. (Fig. 28.1 illustrates the TROL mnemonic) [5, 6].

Fig. 28.1

The TROL mnemonic of fluid prescription: considerations for administration of a fluid bolus in critically ill patients. CO cardiac output, CVP central venous pressure, EVLWI extra vascular lung water index, PVPI pulmonary vascular permeability index. (Adapted with permission from Malbrain et al. [6])

Fluid Prescription: Work Out What You Need!

Maintenance Fluid

Maintenance fluids are given specifically to cover the patient’s daily basal requirements of water and electrolytes. The basic daily needs are summarized in Table 28.3, and a worked example based on body weight is shown in Table 28.4. Some specific maintenance solutions are commercially available, but they are far from ideal. There is a lot of debate whether isotonic or hypotonic maintenance solutions should be used. Data in children showed that hypotonic solutions carry the risk for hyponatremia and neurologic complications. However, studies in adults are scarce and indicate that administration of isotonic solutions will result in a more positive fluid balance as compared to hypotonic solutions. This was confirmed in a recent pilot study in healthy volunteers showing that isotonic solutions caused lower urine output, characterized by decreased aldosterone concentrations indicating (unintentional) volume expansion, than hypotonic solutions and were associated with hyperchloraemia. Despite their lower sodium and potassium content, hypotonic fluids were not associated with hyponatremia or hypokalaemia [17]. This was later also confirmed in critically ill patients undergoing major thoracic surgery [18]. When comparing these studies, administration of an isotonic maintenance solution led to 600 mL fluid gain after 48 h in healthy volunteers compared to 900 mL in ICU patients and a 150 mmol sodium gain after 48 h in healthy volunteers compared to 300 mmol in ICU patients (Fig. 28.2) [11].

Table 28.3 Maintenance fluid requirements. IV intravenous

Table 28.4 Body weights and worked examples

Fig. 28.2

Estimated cumulative fluid and sodium balances of the MIHMoSA and TOPMAST trials. (Adapted with permission from Van Regenmortel et al. [11]). FB fluid balance, SB sodium balance

Important points that need to be considered are.

• Enteral and parenteral feed.

  • The patient may not need the entire calculated maintenance dose per hour if receiving enteral feed and in particular total parenteral nutrition (TPN).

• Time fasting or NBM (nil-by-mouth).

  • Consideration should be given to maintenance fluid in any patient who fasted for over 8 h.

• Drugs = additional fluid!

  • Many IV drugs are administered with large amounts of fluid. These can add large amounts to calculated maintenance rates if forgotten about. Maintenance fluids should be adapted for other fluid sources. Fluid creep must be avoided [12].

• If patients are hypervolaemic.

  • They may require fluid restriction or diuresis. One can try a furosemide stress test (0.1 mg Lasix/kg—patient is responder when UO >200 mL after 2 h).

• Definition of inappropriate fluid prescription in case of electrolyte disturbances.

  • Solutions not containing an adequate amount of sodium in case of hyponatremia from GI losses (Na <135 mmol/L).

  • Solutions not containing an adequate amount of potassium in case of hypokalaemia (K <3.5 mmol/L).

  • Solutions containing too much sodium in case of hypernatremia (Na >145 mmol/L).

  • Solutions containing too much potassium in case of hyperkalaemia (K >5 mmol/L).

Replacement Solutions

If patients have on-going abnormal losses or a complex redistribution problem, the fluid therapy should be adjusted for all other sources of fluid and electrolyte losses (e.g. 0.9% saline may be indicated in patients with hypochloraemic metabolic alkalosis due to gastro-intestinal losses). In general, replacement fluids should mimic the fluid that is lost and should be administered to correct fluid deficits that cannot be compensated for by oral intake. Such fluid deficits might exist, or develop in patients with drains or stomata, fistulas, fever, open wounds (evaporation during surgery, severe burn injury, etc.), and polyuria (salt wasting nephropathy or diabetes insipidus). Data on replacement fluids are also scarce. Several recent guidelines advise matching the amount of fluid and electrolytes as closely as possible to the fluid being lost. An overview of the composition of the different body fluids can be found in the NICE guidelines [2]. Replacement fluids are usually isotonic balanced solutions. In patients with a fluid deficit due to a loss of chloride-rich gastric fluid (leading to metabolic alkalosis), high chloride solutions, like saline (NaCl 0.9%), might be used as replacement fluid.

• Other excessive losses.

  • Some may be more occult, like febrile states leading to excessive evaporative losses in sweat. Consider adding these to your hourly maintenance rate.

  • Gastric losses may be the only indication for 0.9% saline.

• Replacing urinary losses.

  • Urine does not need to be replaced unless excessive in volume (i.e. with diabetes insipidus or the diuretic phase of resolving renal failure).

• Surgical stress response.

  • In post-op patients, polyuria may be multi-factorial. It may be due to excessive intra-operative fluid provision, or secondary to the surgical stress response. Here, increased anti-diuretic hormone release leads to retention of sodium and water but diuresis of potassium-containing urine.

• Prescription inaccuracy.

  • Try and avoid prescribing fluid bags over × number of hours, instead prescribe in mL/h. All patients receiving IV fluids for over 6 h, or those receiving potassium replacement, should all have fluid delivered via a volumetric pump.

  • Adjust administration rates when extra fluid volume is given for the administration of drugs (antibiotics, painkillers, sedatives, etc.)

• Do not increase maintenance fluid rates!

  • Avoid “speeding up” infusions if patients are deemed “non-responders.” This is where IV fluid challenges come in.

• Never adjust IV maintenance rates in order to provide a fluid challenge. These are often left running at the challenge rate, resulting in severe fluid overload. Use a prescribed isotonic fluid challenge separately.

• Do not use dextrose 5% without electrolytes, or NaCl 0.45% in dextrose 5% as a maintenance fluid; 0.18% NaCl/4% glucose is a good alternative; however, care is needed as this does not contain potassium. This may need to be added if the U&E profile suggests it.

Resuscitation Fluid

Resuscitation fluids refer to fluids given to correct an intravascular volume deficit in cases of absolute or relative hypovolaemia (Table 28.5). Resuscitation fluids have received considerable scientific attention, especially in the light of the recent colloid-crystalloid debate. However, a large part of the total infused volume during a patient’s stay in the hospital does not fall into this category.

Table 28.5 Resuscitation fluid guidance

• Sepsis and septic shock.

  • Evidence is mounting against excessive fluid resuscitation in this group, favouring a more restrictive (conservative) vs liberal fluid regimen [19].

  • What many of these patients require is earlier vasopressor support in a critical care environment, or certainly early advice from a senior member of the team/critical care, failing this.

  • For patients in need of fluid resuscitation:

    • The cause of the fluid deficit should be identified.

    • An assessment of shock or hypoperfusion should be made.

    • Patients who have received initial fluid resuscitation should be carefully reassessed.

  • If an excess of 2000 mL (30 mL/kg) IV fluid challenge has been provided, consideration of escalation of the level of care should be made, rather than continuing fluid resuscitation. The more fluid a “septic” patient receives, the higher the morbidity and mortality are likely to be [12, 20]. It may be prudent to liaise with critical care if the situation is deemed complex.

  • Patients who have not had >2000 mL of crystalloids, who still need fluid resuscitation after reassessment, can receive another 200–250 mL of crystalloids and be reassessed again.

  • We recommend caution over the usage of 30 mL/kg resuscitation fluid dosage (as recommended by the Surviving Sepsis Campaign), for all patients [21]. This has been debated worldwide, and the prevailing expert opinion is that this may be excessive. It may be applicable to those who are profoundly shocked with sepsis/SIRS, but should always be paralleled with appropriate escalation and advice from more senior clinicians.

  • We recommend starting with 4 mL/kg over 5 min, with an assessment of the response (check the haemodynamic status and preload tolerance, before and after).

  • Some facts to remember:

    • Less than 50% of haemodynamically unstable patients are “fluid responders”.

    • It is unproven in humans that fluid boluses in septic shock improve cardiac output or organ perfusion.

    • 85% of an infused bolus of crystalloid crosses into interstitial space after 4 h in health. This increases to 95% in sepsis in under 90 min

• For urgent resuscitation:

  • We recommend the use of balanced crystalloid solutions.

  • Hartmann’s solution (compound sodium lactate/Ringer’s lactate) or PlasmaLyte are recommended.

• We do not recommend.

  • The use of 0.9% sodium chloride. This is a very poor choice of IV fluid in shock states with acidosis or AKI, as this fluid potentiates further imbalance (hyperchloraemic metabolic acidosis). It contains a supra-physiological amount of sodium and chloride (both 154 mmol/L) and is therefore not isotonic.

  • Dextrose 5% or any other hypotonic solution as a resuscitation fluid.

• Colloid controversy.

  • There are controversies behind the usage of colloids, as they are not without their problems (high sodium load, incidence of allergic reactions, etc.).

  • Crystalloids are likely to be a safer first choice.

  • Hypertonic albumin 20% can be considered during the later de-resuscitation phase, although there may be a beneficial effect in a small subgroup of patients with severe septic shock.

  • Do not use starch solutions in septic shock, burns, or patients with AKI. Starch solutions can still be used in trauma and perioperative hypotension.

  • Do not use albumin 4%.

  • Do not use gelatins; there is limited evidence supporting their use in critically ill patients.

• Bleeding.

  • The priority is to locate and stop the bleeding.

  • The best replacement for this is blood and any accompanying blood products.

  • Consider initiating the massive haemorrhage protocol through a switchboard.

  • Do not forget calcium, tranexamic acid, and fibrinogen substitution when needed.

Appropriateness of IV Fluid Therapy

The appropriateness of IV fluid therapy should always be checked by looking at the clinical assessment of fluid status, checking the indication for IV fluid therapy, correct prescription, and management. This is summarized in Table 28.6.

Table 28.6 Four stages to check for the appropriateness of IV fluid therapy

Which IV Fluid?

• Knowledge of IV fluid constituents:

  • Be wary of what each bag of fluid contains. Many IV fluids contain a lot of sodium! (See Table 28.7).

Table 28.7 IV fluid constituents

• Fluid of choice.

  • Maintenance: 0.18% saline with 4% dextrose with/without potassium or any ready off-the-shelf balanced solution (Glucion, Maintelyte).

    • At the correct rate, this should give a balanced solution. Be mindful of the fact there is no potassium in this solution, and it must be added if the patient is hypokalaemic. Excessive amounts can cause hyponatraemia/hypokalaemia.

  • Resuscitation: Hartmann’s solution/Ringer’s lactate or compound sodium lactate or PlasmaLyte.

    • Again, a balanced safe solution. If the patient already has a sodium of less than 132 mmol/L, the use of Hartmann’s or PlasmaLyte may be the preferred option. Contains potassium.

    • Intuitively one would argue not to use these fluids if the patient has hyperkalaemia; however, there is no contraindication to their use, and in the end, they may even lower serum potassium levels in mild AKI as compared to saline (leading to metabolic acidosis and secondary increase in potassium even if saline does not contain potassium). Also remember that adding an IV solution containing potassium at 5 mmol/L will not increase K in a patient with mild AKI and a potassium level of 6 mmol/L. On the contrary, potassium will be diluted as well.

• Potassium supplementation.

  • Can be added to 0.18% saline with 4% dextrose and normal saline.

  • Can be added to 5% dextrose (though we strongly discourage this fluid’s usage in maintenance/resuscitation).

  • Do not add to Hartmanns for reason of stability!

  • If the potassium is already greater than 5 mmol/L, do not add extra potassium to any IV fluid.

  • All potassium-containing fluids should be administered via an appropriate volumetric pump.

• Re-feeding syndrome.

  • Signs: hypophosphatemia, hypomagnesemia.

  • Consider Pabrinex Intravenous High Potency, Concentrate for Solution for Infusion (supplied in pairs of amber glass ampoules of 5 mL) if the patient is at risk of refeeding syndrome, (take this volume into account when calculating their maintenance).

• DO NOT USE 5% dextrose as a maintenance nor resuscitation fluid.

• DO NOT USE colloids as a maintenance fluid.

  • Associated complications and high sodium loads!

• DO NOT USE 0.9% (ab)normal saline for any prolonged period.

  • It has a high sodium and chloride load!

• DO NOT USE maintenance solutions for resuscitation.

• DO NOT USE resuscitation fluids for maintenance use.

Difficult Situations and Tips

• Consider assessment of haemodynamic response to 45° passive leg raise test (See Fig. 28.3).

  • Did the BP increase (10–15%) and pulse rate slow down after 30–50 s?

    • If yes, they are likely to be a fluid responder.

    • If no, consider the fact they may not be hypovolaemic and there is something else going on.

Fig. 28.3

Trolley assisted passive leg raise. The passive leg raising (PLR) test. In order to perform a correct PLR test, one should not touch the patient in order to avoid sympathetic activation. The PLR is performed by turning the bed from the starting position (head of bed elevation 30–45°) to the Trendelenburg position. The PLR test results in an autotransfusion effect via the increased venous return from the legs and the splanchnic mesenteric pool. Monitoring of stroke volume is required as a positive PLR test is defined by an increase in SV by at least 10%. See the text for explanation. (Adapted from Hofer et al. with permission [22])

• Consider urinary catheter in all sick patients.

• Signs of hypovolaemia may be unreliable in:

  • Elderly patients.

    • Often concomitant drugs slow heart rate, e.g. Beta blockers, digitalis, certain calcium-blockers. This may attenuate any pulse rate responses.

    • Normal target blood pressures (MAP >65 mmHg) in the elderly may be too low for them if they are normally hypertensive. Diastolic blood pressure may be low in elderly with systolic hypertension and diastolic heart failure (be aware of false-positive PLR).

    • Cardiac pathologies and dysautonomic states can cloud responses to fluid challenges and hypovolaemic states.

  • Young fit patients.

    • High physiological reserve capacity.

    • Rapid adrenergic compensatory pressure response to intravascular volume loss. Therefore, much delayed vital sign deterioration.

• Excessive losses.

  • Calculate the losses over the previous 24 h.

  • Consider replacement using Hartmanns or PlasmaLyte in combination with maintenance,

  • If upper GI loss, with low chloride, use 0.9% NaCl.

• See Table 28.8 for electrolyte emergencies.

  • Hyponatraemia: The causes of this are varied and complex. A sodium less than 125 mmol/L can be dangerous and senior input should be sought. The treatment for low Na is nearly always fluid restriction; not 0.9% sodium chloride.

  • Potassium: Just because the potassium level is normal, does not necessarily mean that there isn’t a deficit, therefore consider adding it to replacement fluid.

Table 28.8 Common electrolyte emergencies

• Escalation of the non-responder and consider critical care review if:

  • GCS ≤8 or falling from a higher level.

  • O₂ saturation lower than 90% on 60% oxygen or higher.

  • PaCO₂ >7 kPa (or 52 mmHg) unresponsive to noninvasive ventilation (NIV) or CPAP.

  • Persistent hypotension and/or oliguria unresponsive to 2 L fluid and/or concern of cardiac function.

  • Metabolic acidosis: base deficit < −8 or worse, bicarbonate <18 mmol/L, lactate >3 mmol/L and not improving in 2 h with treatment.

  • Aggressive or agitated patients whose treatment is compromised due to their agitation.

  • Complex pathologies/disease states require closer monitoring than a ward-based level 0 setting can offer.

An overall fluid management infographic example is given in Fig. 28.4.

Fig. 28.4

Overall fluid management infographic. (Courtesy from Wilkinson JN, Lyness D, endorsed by the International Fluid Academy)

Case Vignette

Questions and Answers

• Q1. What information do you need to safely prescribe IV fluids to the patient?

• A1. The following information should be sought, prior to prescription.

  • 1. Fluid status—(hypo/eu/hypervolaemia)

  • 2. Weight change in the last 24 h

  • 3. Urea and Electrolytes in the last 24 h

  • 4. Fluid balance—(Input and output) over the last 24 h

• Q2. How will you write a prescription for IV fluid for this patient?

• A2. The prescription should contain the following elements

  • 1. Drug—what fluid.

  • 2. Dose—mL/h, via a volumetric pump.

  • 3. Duration—for example, 24 h only or until drinking.

  • 4. De-escalation—there should be a clear stop point, or tapering instruction.

Rare example of appropriate use of 0.9% saline!

Persistent and unrelenting vomiting, for example, causes both hypovolaemia AND a state of hyponatraemic, hypokalaemic metabolic alkalosis. This can also occur due to extensive upper GI NG losses.

0.9% sodium chloride will be a suitable drug to replace these losses but over a limited and controlled, well-monitored period.

Conclusion

In conclusion, the management of intravenous fluid therapy is a critical aspect of patient care, with significant implications for patient safety and outcomes. As highlighted in this chapter, improper fluid prescribing can lead to morbidity and mortality, making it essential to invest in efforts to improve this practice. National guidelines, such as those from the National Institute for Health and Care Excellence (NICE), provide a valuable framework for improving fluid prescription, but effective implementation requires dedication, resources, and ongoing monitoring.

To address the challenges and pitfalls associated with implementing large-scale changes in fluid prescription, healthcare providers should follow a stepwise approach, including team establishment, baseline audits, identifying barriers, engaging medical and nursing leaders, and continuous monitoring and improvement.

By following these principles, healthcare professionals can enhance patient safety and provide more effective care in various clinical settings, including the operating room, emergency room, and intensive care unit. Ultimately, ongoing efforts to improve fluid prescription practices are essential to ensure the well-being of patients and reduce unnecessary risks and costs associated with suboptimal fluid management.

Take Home Messages

There are key points for the implementation of a safe IV fluid policy [23]:

• Establish a feeling of urgency and focus on the three existing problems:

  • Clinical harm.

  • Poor education among prescribers.

  • Lack of accurate fluid balance charting.

• Build a coalition team of willing participants and transgress the usual boundaries by involving the multi-disciplinary team.

• Develop a strategy to be able to give the right amount of the right fluid, at the right time, to the right patient.

• Enlist and present results and plans to stakeholders.

• Generate goals.

• Engage the team with plenty of on-going education sessions for nurses, junior doctors, nurse prescribers, and consultants.

• Embrace modern technology and the digital revolution with E-learning modules or Apps.

• Sustain and capitalize on wins and gains to produce even bigger results.

• Institute and incorporate the programme into the culture of the organization.

• Spread the message—standardize practice and education to improve patient care and propagate a hopeful decrease in morbidity and mortality.