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Copyright EMAP Publishing 2018 This article is not for distribution except for journal club use

Clinical Practice Keywords Crystalloid//Blood products/Osmolarity Review This article has been Fluid therapy double-blind peer reviewed In this article... ● Causes of insensitive and sensitive fluid loss in critically ill patients ● Different types of intravenous fluids, their indications and side-effects ● Guidance on the treatment of fluid loss and fluid algorithm

Selecting IV fluids to manage fluid loss in critically ill patients

Key points Authors Xabi Cathala is a lecturer in vocational learning, Institute of Vocational Intravenous fluid Learning; Calvin R Moorley is an associate professor in adult nursing, Faculty of therapy is one of Health and Social Care; both at London South Bank University. the most common treatments in Abstract Critically ill patients admitted to intensive care settings may need to be intensive care administered intravenous fluids – for example, to restore their blood pressure or replace lost blood. A crucial question arising in the management of these patients Fluid loss leads to is which type of fluid to use. To decide which fluid is most appropriate and safest, hypovolaemia and, nurses working in critical care need to understand how the different types of fluids if left untreated, act on the human body. This article describes the three main types of fluids to death (crystalloids, and blood products), their composition, mode of action, indications and side-effects. Crystalloids vary in their osmolarity Citation Cathala X, Moorley C (2018) Selecting IV fluids to manage fluid loss in and so have critically ill patients Nursing Times [online]; 114: 12, 41-44. different indications

Colloids contain ntravenous (IV) fluid replacement is Sensible fluid loss, which can be seen macromolecules one the most common treatments and measured, can be due to diarrhoea, that increase administered in intensive care and vomiting, haemorrhage, high output from vascular pressure, Iother critical care areas (Myburgh and drains or stomas, wounds or excessive diu- resulting in plasma Mythen, 2013). Three types of fluids are retic therapy. is another cause of volume expansion used: crystalloids, colloids and blood prod- fluid loss, as it causes an intravascular ucts; in our experience, their use varies fluid deficit due to vasodilatation, venous There is a lack of between hospitals and practitioners. It is pooling and capillary leakage (Marx, 2003). conclusive evidence important that nurses understand the dif- on which fluid to use ferent types of fluids, their mechanisms of Treatment of fluid loss for treating fluid loss action and side-effects. This article pro- Acutely ill patients who experience fluid vides essential information on fluid resus- loss will need to be administered IV fluids. ciation in critical care. Where fluid loss is significant, replace- ment is urgent and this is known as fluid Fluid loss resuscitation. As with all drug treatments, Fluid loss can lead to hypovolaemia and, if IV fluids must be correctly prescribed by a left untreated, to death. In acutely ill doctor or a non-medical prescriber. One of patients, fluid loss can occur from insen- the roles of nurses is to ensure this is done sible and/or sensible loss. according to organisational policies. How- Insensible fluid loss cannot always be ever, if the patient’s condition is life- seen and measured; examples include threatening, the National Institute for sweating, fluid loss from the gastrointes- Health and Care Excellence advocates that tinal tract (for example, via reabsorption) nurses should be able to start IV fluids

and fluid loss from the lungs (loss of H2O according to organisational policy until via respiration), which can be up to 800ml they are prescribed by a relevant practi-

ALAMY in 24 hours (El-Sharkawy et al, 2017). tioner (NICE, 2013).

Nursing Times [online] December 2018 / Vol 114 Issue 12 41 www.nursingtimes.net Copyright EMAP Publishing 2018 This article is not for distribution except for journal club use Clinical Practice Review

Indications for fluid resuscitation Fig 1. Fluid resuscitation algorithm in adults In its guidance on IV fluid therapy in adults in hospital, the NICE (2013) lists the fol- Step 1: Using the ABCDE (Airway, Breathing, Circulation, Disability, Exposure) lowing criteria for fluid resuscitation: approach, assess whether the patient is hypovolaemic and needs fluid resuscitation l Systolic blood pressure <100mmHg; Assess fluid volume considering clinical examination, trends, context and indicators l Heart rate >90 beats per minute; that a patient may need fluid resuscitation (see text) l Capillary refill time >2 seconds or peripheries cold to touch; Yes l Respiratory rate >20 breaths per minute; Fluid resuscitation l National Early Warning Score ≥5 Step 2: Initiate treatment or more; • Identify cause of fluid deficit and respond l Passive leg raising suggesting fluid • Give a fluid bolus of 500ml of crystalloid (containing sodium responsiveness (Box 1). in the range of 130-154mmol/L) over less than 15 minutes To help health professionals in their decision-making, the NICE guideline includes algorithms for IV fluid therapy Step 3: Reassess the patient using the ABCDE approach (Bit.ly/NICEFluidAlgorithms). The algo- Does the patient still need fluid resuscitation? Seek expert help if unsure rithm for fluid resuscitation (Fig 1) fea- No tures three steps: l Step 1: ABCDE (Airway, Breathing, Yes Does the patient have signs of shock? Circulation, Disability, Exposure) Yes No Assess the patient’s assessment; likely fluid and l Step 2: initiating treatment – the needs algorithm indicates how much fluid to Yes give over a specific period; timing is >2,000ml given? Seek expert help important: if given too slowly, resuscitation will be less effective; No l Step 3: reassessment. It is important to monitor patients Give a further fluid bolus of 250-500ml of crystalloid during fluid resuscitation. Systemic obser- vations should be undertaken frequently Adapted from NICE (2013) according to organisational policy. It is good practice to assign the monitoring to a Nurses need to be able to identify the side- dextrose , 0.33% NaCl (sodium specific nurse. Haemodynamic observa- effects of IV fluids, which include fluid chloride), 0.45% NaCl, 2.5% dextrose, tions should include blood pressure (BP), overload, oedema and anaphylactic reac- 5% dextrose and 5% (an heart rate, heart rhythm, oxygen satura- tion. Early recognition of complications isotonic fluid, which is quickly tion and capillary refill time. If the patient and side-effects is essential to preserve metabolised, leaving free water that has a central venous catheter in situ, cen- patients’ safety. is hypotonic). tral venous pressure should be measured. l Hypertonic crystalloids, which include Respiratory rate and urine output also Crystalloids 3% NaCl, 5% NaCl, 7% NaCl, 10% need to be assessed and recorded. Fluid Crystalloid contain dextrose, 20% dextrose and 50% dextrose balance should be maintained or com- and glucose. Osmolarity (Box 2) is an (Lira and Pinsky, 2014; Gan 2011). menced and accurately recorded. important property of crystalloids, which The observations will show trends in can be classified into four subgroups: Properties and indications the patient’s status and how the patient l Isotonic crystalloids – the most Different types of crystalloids have dif- reacts to the treatment that you initiated. commonly used is ferent properties and will, therefore, be They also will allow early recognition of 0.9% (normal saline); appropriate in different situations possible complications such as shock. l Balanced isotonic crystalloids – the according to the cause of fluid loss and the most commonly used are Ringer’s patient’s condition. Box 1. How to ascertain fluid lactate and Hartmann’s ; Isotonic crystalloids have a sodium and responsiveness l Hypotonic crystalloids, which include a chloride concentration of 154mmol/L and

To ascertain a patient’s responsiveness Box 2. What is osmolarity? to fluid therapy, lay them down horizontally and raise their legs 45 Osmolarity measures the number of osmoles of solute particles per unit volume of degrees so the blood returns to the solution. It is defined as the number of osmoles (Osm) of solute per litre (L) of central circulation. If the blood pressure solution and expressed as Osm/L (pronounced ‘osmolar’). This value allows us to increases within 30-90 seconds, the measure the osmotic pressure of a solution and determine how its particles will patient is likely to be responsive to fluid diffuse across a semi-permeable membrane separating two solutions of different therapy to restore blood pressure. osmotic concentrations (osmosis).

Nursing Times [online] December 2018 / Vol 114 Issue 12 42 www.nursingtimes.net Copyright EMAP Publishing 2018 This article is not for distribution except for journal club use Clinical Practice Review a similar electrolyte concentration to Box 3. Case scenario plasma. With isotonic infusions, there is no significant fluid shift across cellular or Tom Stevens* is admitted to the l Capillary refill time >3 seconds vascular membrane for a normally (ICU) via accident As per national guidance (NICE, 2013), hydrated patient (Lira and Pinsky, 2014; and emergency (A&E) for optimisation Mr Stevens would be initially treated Gan, 2011). These fluids are usually used to before surgery. Handover notes from as follows: treat low loss (for the A&E nurse indicate a two-day l Administer a 500ml crystalloid bolus example, in a dehydrated patient), in fluid history of diffuse , over 15 minutes then reassess; challenge or during fluid resuscitation. and several episodes of vomiting. l If reassessment shows he still needs Balanced isotonic crystalloids contain Mr Stevens has not been able to tolerate fluid, a further crystalloid bolus of less sodium and chloride than sodium any oral intake. His bowel movements 250-500ml can be administered; chloride 0.9% (Lira and Pinsky, 2014; Gan, were normal until the previous day, when l The cycle can be repeated if required 2011); however, they contain potassium, he had four liquid bowel movements. until 2000ml of crystalloids has been calcium and lactate. They are called ‘bal- A central venous catheter, urinary administered; anced’ because their ionic composition is catheter and peripheral cannula have l Regarding Mr Stevens’ closer to the human body’s plasma levels been inserted in A&E. history, haemoglobin and haematocrit than other crystalloids. A post-operative On admission to the ICU, Mr Stevens levels should be tested. This will patient at risk of fluid loss leading to elec- has two episodes of haematemesis indicate if a is trolyte imbalance, for example, will ben- (vomiting of blood). His observations needed and confirm if Mr Stevens’ efit from balanced crystalloids. were as follows: blood is diluted – this can occur due Hypotonic crystalloids have a lower l Blood pressure 75/35mmHg; to fluid resuscitation; osmolarity than plasma (Lira and Pinsky, l Mean arterial pressure 50mmHg; l Medical staff should be informed 2014; Gan, 2011), which means they cause l Heart rate 120 beats per minute; of the situation so they can decide fluids to shift from the intravascular space l Respiratory rate 25 breaths per whether to continue with crystalloids to the intracellular or interstitial space minute resuscitation, or administer blood (Lira and Pinsky, 2014; Gan, 2011). They also l Oxygen saturation 91% (on room air) or colloids. help the kidneys excrete fluids and electro- l Central venous pressure +2mmHg * The patient’s name has been changed lytes, and are often used in patients with diabetic ketoacidosis. Hypertonic crystalloids have a higher With hypertonic crystalloids, the main dextran 40 and dextran 70 (the numbers electrolyte concentration than plasma risks are hypernatraemia and hyperchlo- relate to the solutions’ molecular weight). and, therefore, draw fluid from the intra- raemia, so these fluids need to be given HES are synthesised from amylopectin, cellular and interstitial space into the slowly and cautiously to avoid intravas- a water-soluble polysaccharide derived intravascular space (Lira and Pinsky, 2014; cular fluid overload and pulmonary from maize or sorghum (Lira and Pinsky, Gan, 2011). They may be used to treat oedema (Adam et al, 2013). It is also worth 2014, Gan, 2011) and contain sodium and patients with cerebral oedema. noting that 20% dextrose is an osmotic chloride. An example is Voluven. diuretic. Hypertonic solutions should not Side-effects and precautions be given to patients with cardiac condi- Properties and indications Isotonic crystalloids should be used with tions, as there is a risk of fluid overload. A key property of colloids is their duration caution in patients with cardiac or renal of PVE, which is determined by their rate disease, as there is a risk of fluid overload. Colloids of loss from the intravascular space, which Patients’ sodium and chloride levels need Colloids contain macromolecules that mainly occurs: to be monitored regularly to avoid hyper- increase vascular pressure (oncotic pres- l Through the capillary endothelial natraemia and hyperchloraemia. sure), resulting in plasma volume expan- barrier into the interstitial space; The lactate contained in balanced iso- sion (PVE) (Lira and Pinsky, 2014; Gan, l Through the renal glomerulus into tonics is metabolised by the liver into 2011). They can be classified into three urine (Gan, 2011). bicarbonate (Adam et al, 2017), so these main types according to how they are pro- Gelatins have a PVE of 0.2L after 90 min- fluids should not be used in patients who duced: utes for one litre administered, which is cannot metabolise lactate due to liver dis- l Gelatins; equivalent to crystalloids. Dextrans and ease or lactate acidosis; nor should they be l Dextrans; HES have a PVE of around 0.7L and 0.8L, administered to patients with pH >7.5. l Hydroxyethyl starches (HES). respectively, for one litre administered (Gan, They should be used with caution in Gelatins are prepared by hydrolysis of 2011). Because of their long PVE, colloids are patients with renal failure because of the collagen (chemical breakdown of collagen often used in patients who are bleeding. kidneys’ inability to filter potassium. All due to a reaction with water). They also isotonic crystalloids can cause peripheral contain electrolytes such as sodium and Side-effects and precautions and pulmonary oedema. chloride (Lira and Pinsky, 2014; Gan, 2011). A notable effect of colloids is haemodilu- Hypotonic crystalloids should not be Gelofusine belongs to this category. tion, which occurs due to the amount of administered to patients at risk of Dextrans are biosynthesised from fluid kept in the intravascular space. This increased intracranial pressure, those with sucrose by leuconostoc bacteria using the can affect homoeostasis. liver disease or trauma or patients, enzyme dextrose sucrase (Gan, 2011; Lira Gelatins cause the least disturbance of mainly because these patients need to and Pinsky, 2014). Dextrans contain homoeostasis but have been associated maintain a good intravascular volume. sodium and chloride. Examples are with reduced levels of some clotting

Nursing Times [online] December 2018 / Vol 114 Issue 12 43 www.nursingtimes.net Copyright EMAP Publishing 2018 This article is not for distribution except for journal club use Clinical Practice For more articles on critical care, go to Review nursingtimes.net/criticalcare factors (Gan, 2011). HES are the only col- attention must be paid to the risk of ana- with colloids vs crystalloids on mortality in critically ill patients presenting with : the loids reported to produce coagulopathy phylactic reactions and the compatibility CRISTAL randomized trial. Journal of the American and an increase in blood loss after surgery of the product with the patient’s blood Medical Association; 310: 17, 1809-1817. (Gan, 2011). Dextrans, which are effective group needs to be carefully checked. Barron ME et al (2004) A of the comparative safety of colloids. Archives of Surgery; antithrombotic agents, are associated with 139: 552-563. more significant homoeostatic distur- Inconclusive evidence Curry N et al (2015) Early for major bance (Gan, 2011). The vast number of studies published on IV haemorrhage in trauma: a randomised controlled Anaphylactic reactions have been fluid therapy show the importance of the feasibility trial. British Journal of Anaesthesia; 115: 1, 76-83. described with all colloids; the incidence subject, but the evidence is inconsistent, in Dean L (2005) Blood Groups and Red Cell of severe reactions seems to be higher particular on the question of whether to Antigens. Bethesda, MD: National Center for with gelatins. Colloids, especially HES, administer crystalloids or colloids (Perel Biotechnology Information. El-Sharkawy AM et al (2017) and also seem to affect kidney function (Niemi and Roberts, 2013; Phillips et al, 2013). clinical outcome in hospitalised older adults: a et al, 2010). Annane et al, (2013) found no difference cohort study. European Geriatric Medicine; 8: 1, in terms of mortality between colloids and 22-29. Gan TJ (2011) Colloid or crystalloid: any differences Blood products crystalloids at 28 days, although colloids in outcomes? Presentation at the 2011 annual Blood products used for fluid therapy seemed better than crystalloids at 90 days meeting of the International Anesthesia Research include: in terms of patient outcomes. A few Society, Vancouver, 21-24 May 2011. Kaufman RM et al (2015) transfusion: a l  Red blood cells – one of the components studies reported no evidence of benefits clinical practice guideline from the AABB. Annals of blood; they are derived from whole using colloids instead of crystalloids (Lira of Internal Medicine; 162: 3, 205-213. blood by centrifugation (Dean, 2005); and Pinsky, 2014; Myburgh and Mythen, Lira A, Pinsky MR (2014) Choices in fluid type and volume during resuscitation: impact on patient l  (FFP) – the liquid 2013; Perl et al, 2007), highlighting that it outcomes. Annals of Intensive Care; 4: 4, 38. part of blood; it contains all soluble was difficult to justify the use of colloids Marx G (2003) Fluid therapy in sepsis with coagulation factors, including factors because of their high cost. capillary leakage. European Journal of Anaesthesiology; 20: 6, 429-442. V and VIII (Prowle et al, 2010; However, other studies showed an Mutter TC et al (2013) Hydroxyethyl starch (HES) O’Shaughnessy et al, 2004); increase in mortality with the use of col- versus other fluid therapies: effects on kidney l Cryoprecipitate – contains a loids (Taylor and Bromilow, 2013; Zary- function. Cochrane Database of Systematic concentrated subset of FFP chanski et al, 2013; Gan, 2011). Others again Reviews; 7: CD007594. Myburgh JA, Mythen MG (2013) Resuscitation components including fibrinogen, showed that colloids increased the risk of fluids.New England Journal of Medicine; 369: 13, factor VIII, von Willebrand factor and the need for renal 1243-1251. and factor XIII (Curry et al, 2015); replacement therapy (Mutter et al, 2013; National Institute for Health and Care Excellence (2013) Intravenous fluid therapy in adults in l  – one of the components of Myburgh and Mythen, 2013; Taylor and hospital. Nice.org.uk/cg174 blood; a single platelets unit is derived Bromilow, 2013; Zarychanski et al, 2013; Niemi TT et al (2010) Colloid solutions: A clinical from one unit of and Wiedermann et al, 2010). update. Journal of Anesthesia; 24. 913-25. O’Shaughnessy DF et al (2004) Guidelines for the should be used within five days While the studies cited above suggest use of fresh-frozen plasma, cryoprecipitate and (Kaufman et al, 2015); colloids are less safe than crystalloids . British Journal of Haematology; l Albumin – a protein synthesised by during resuscitation, crystalloids are not 126: 1, 11-28. Perel P, Roberts I (2013) Colloids versus the liver. harmless and do have side-effects crystalloids for fluid resuscitation in critically ill (Myburgh and Mythen, 2013). Most of these patients. Cochrane Database of Systematic Properties and indications studies raise the question of the safety of Reviews; 2, CD000567. Phillips DP et al (2013) Crystalloids vs. colloids: KO Red blood cells can be administered to main- colloids, especially HES; gelatines have at the twelfth round? Critical Care; 17: 3, 319. tain an acceptable haemoglobin level and been less investigated than HES and their Prowle JR et al (2010) Fluid balance and acute blood volume in patients with blood loss, safety cannot be confirmed (Thomas- kidney injury. Nature Reviews Nephrology; 6: 2, 107-115. thereby ensuring a good delivery of oxygen. Rueddel et al, 2012). Taylor MG, Bromilow J (2013) hydroxyethyl starch FFP is administered in specific cases, Amid this lack of conclusive evidence, 130/0.42 versus ringer’s acetate in severe sepsis. such as liver disease, severe infection or the NICE 2013 guidance gives clear indica- Journal of the Intensive Care Society; 14: 1, 82-83. Thomas-Rueddel DO et al (2012) Safety of gelatin disseminated intravascular coagulation tions on how to treat fluid loss in critically for volume resuscitation – A systematic review and (Adam et al, 2017). ill patients. Nurses should refer to the meta-analysis. Intensive Care Medicine; 38: 7, Platelets stop bleeding, so they can be guidance and any local protocols and poli- 1134-1142. administered to patients who are bleeding cies. The case scenario in Box 3 describes Wiedermann CJ et al (2010) Hyperoncotic colloids and acute kidney injury: a meta-analysis of (or at high risk of bleeding) and/or who the case of a patient who needed fluid randomized trials. Critical Care; 14: 5, R191. report a low platelet count. therapy to maintain his blood pressure. By Zarychanski R et al (2013) Association of Albumin has plasma expansion proper- developing their knowledge and under- hydroxyethyl starch administration with mortality and acute kidney injury in critically ill patients ties (Barron et al, 2014) and also raises vas- standing of the different types of fluids requiring volume resuscitation: a systematic review cular pressure (Wiedermann et al, 2010). It and their effects on the human body, and meta-analysis. Journal of the American can be used to compensate fluid lost from nurses can improve their ability to offer Medical Association; 309: 7, 678-688. an ascites drain, for example. evidence-based care. NT

References For more on this topic online Side-effects and precautions Adam S et al (2017) Critical Care Nursing – Science A transfusion of blood products will and Practice (3rd edn). Oxford: Oxford University l Choosing between colloids and increase iron and potassium levels. All Press. Adam S et al (2013) Rapid Assessment of the crystalloids for IV infusion blood products must be administered Acutely Ill Patient. Chichester: Wiley. Bit.ly/NTSCFluids according to organisational protocols; Annane D et al (2013) Effects of fluid resuscitation

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