Fluid Therapy in Critical Illness

Transcription

1 Fluid Therapy in Critical Illness Ruth Roadley-Battin Advanced Clinical Pharmacist- Critical Care, UHB With thanks to Dr Zahid Khan, Emma Boxall and Fraser Hanks.

2 Fluids in Critical Care Most common intervention in acute medicine Controversy: type, amount and timing

3 FLUIDS are MEDICINES Fluid prescription MUST be given the same status as drug prescription Paracelsus Poison is in everything, and no thing is without poison. The dosage makes it either a poison or remedy

4 NICE Guideline 2013.MANY STAFF WHO PRESCRIBE IV FLUIDS KNOW NEITHER THE LIKELY FLUID AND ELECTROLYTE NEEDS OF INDIVIDUAL PATIENTS, NOR COMPOSITION OF IV FLUIDS AVAILABLE TO THEM..OFTEN DELEGATED TO THE MOST JUNIOR MEDICAL STAFF WHO FREQUENTLY LACK THE RELEVANT EXPERIENCE 1 IN 5 PATIENTS SUFFER MORBIDITY DUE TO INAPPROPRIATE FLUID THERAPY POOR FLUID CHART BALANCE DOCUMENTATION INTRAVENOUS FLUID THERAPY IN ADULTS IN HOSPITAL. DEC NICE CLINICAL GUIDELINE 174 GUIDANCE.NICE.ORG.UK/CG174

5 Objectives of Session Understanding of Physiology History Which fluids to give? How much fluid to give? Assessment of the fluid balance When to start, stop, restrict or remove fluids?

6 Basics Total body water M~60% = 42L 70kg male F~50% = 35L 70kg female - fat has a lower water content than muscle!

7 Total Body Water Plasma ECF Interstitial Fluid ICF Intracellular fluid 3 L 11 L 28 L Capillary membrane Cell membrane Intravascular Extracellular

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9 The normal Composition of Major Body Fluid compartments Plasma (mmol/l) Interstitial Fluid (mmol/l) Intracellular Fluid (mmol/l) Na K Ca Mg Cl HCO PO SO Organic acid Protein

10 Diagram of Ernest Starling s forces at a capillary

11 Glycocalyx

12 RSE and the Glycocalyx

13 Revised primary forces Lira and Pinsky 2014

14 Daily fluid balance (70kg adult) Sensible / Measured Input: 1000ml (liquids) Output: Urine 1300ml Insensible / Unseen Input: 800ml from food, 300ml water of oxidation = total of 1100ml Output : skin, lungs, faeces = total of 800ml = 2100 ml INPUT = 2100 ml OUPUT Therefore 70kg adult needs approx. 2L per day if NBM ~ 30ml/kg/day (approx ml/kg/hr - under normal conditions)

15 Water balance Intake controlled by thirst Excretion - controlled by ADH/vasopressin -> water reabsorption. Osmolarity Plasma osmolalities >280 mosm sensitises osmoreceptors in the brain - initiates thirst ADH secretion -> water reabsorption Circulating volume Decreased blood volume (atrial stretch receptors) and decreased blood pressure (baroreceptors) also stimulate ADH secretion.

16 Water homeostasis High plasma osmolarity ADH release and water reabsorbed (via insertion of aquaporins in DCT & collecting ducts) Drop in blood pressure Activation of RAAS Aldosterone causes absorption of Na + (& therefore H 2 0) from DCT. Also get vasoconstriction & ADH secretion

17 ASSESSMENT Does the patient need iv fluid?

18 Assessment of Fluid Balance History Clinical Examination Laboratory assessment

19 Assessment Assess fluid and electrolyte needs from history, clinical examination, current medications, clinical monitoring and laboratory investigations: History should include any previous limited intake, thirst, the quantity and composition of abnormal losses, and any comorbidities, including patients who are malnourished and at risk of refeeding syndrome. Clinical examination assess patient's fluid status, including:

20 Clinical Examination BP Capillary refill time Urine output Postural hypotension Presence of peripheral oedema More invasive techniques such as CVP, CO monitoring Thirst Primary stimulus Missing in some patients Skin turgor Pulse Sunken eyes Furrowed tongue Weight change Oliguria (U/o < 0.5ml/kg/hr)

21 Assessing the patient Has the patient been starved (e.g. Pre op)? Do they have an iv infusion in progress? Are there any reasons to expect excess losses (e.g. Due to type of surgery, burns etc)? Diuretics? Pyrexia? Vomiting / ng tube Diarrhoea / bowel prep Third space losses

22 Assessing the patient From NICE elearning on fluids

23 Assessment of fluid status Assess whether the patient is hypovolaemic and in need of urgent fluid resuscitation: systolic blood pressure is less than 100 mmhg heart rate is more than 90 beats per minute capillary refill time is more than 2 seconds or peripheries are cold to touch respiratory rate is more than 20 breaths per minute National Early Warning Score (NEWS) is 5 or more passive leg raising suggests fluid responsiveness fluid balance charts weight. Laboratory investigations should include current status and trends in:

24 Urea Creatinine Electrolytes Serum osmolality (mosmol/l) = 2(k + +na + ) + glucose + urea Normal = 290 mosmol/l Laboratory Assessment Haematocrit, haemoglobin

25 Setting a fluid balance Assess volume status consider inputs Vs losses in last 24 hours Assess clinical status resus / stabilisation / recovery Inputs parenteral fluids, parenteral medication, enteral feeds, and oral fluids Outputs urine output, N&V, ultrafiltrate (if on RRT), insensible losses, loss of fluid from drains and faecal loss It is not an exact science and patient pathology can change markedly during the day, thus fluid balance target has to be adjusted

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28 Fluids timeline

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30 Aims of Fluid Administration Replace normal fluid and electrolyte lossesmaintain stability Maintain BP, CO and tissue perfusion to meet metabolic demands of the tissues, aid temperature regulation and facilitate waste removal Replenish losses/deficits Avoid excessive tissue oedema

31 Type of Fluid replacement Intravenous Fluids Crystalloids Colloids Sodium chloride 0.9%/Balanced solution Glucose Various strength Blood products Packed red cells Platelets, FFP Albumin Gelatins

32 FLUID CONTENT OF THE BODY Staples et al 2008

33 Crystalloids Iso-osmotic with plasma. Distribution determined by sodium concentration Contain low molecular weight salts or sugar dissolved in water In theory several times more crystalloid than colloid is required to achieve the same degree of vascular filling Crystalloid solutions move rapidly into the interstitial compartment Crystalloid resuscitation may lead to interstitial oedema

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36 Na + mmol/l Cl - mmol/l K + mmol/l Ca 2+ mmol/l HCO3 - mmol/l ph Glucose g Osmol mosmol/l 0.9% NaCl Hartmann s Solution (CSL) As lactate Glucose 5% (50g/L) Plasma-Lyte Glucose 4% (40g/L) /NaCl 0.18% with KCl % NaHCO Plasma

37 Glucose 5% Electrolyte free, disperses through ICF and ECF as water. Very small % remains in blood after distribution Source of energy/nutrition 1L provides 200kcal on metabolism No risk of anaphylaxis Can cause water intoxication- worsen cerebral oedema, hyponatraemia Use increased concentration (20/50%) for nutrition. Note 50% very irritant, central line only Used for: Immediate hydration Supply of basal H 2 O requirements over and above electrolyte requirements Drug adminstration

38 Sodium Chloride 0.9% Disperses through out ECF not ICF Used to replace blood loss requires 3 x vol of blood lost Can cause hyperchloraemic acidosis Fluid of choice in hypochloraemia eg due to vomiting Risk of hypernatraemia if pt has Na retention Daily requirement of 70-80mmol sodium is normal Consider excess losses through sweat/gi tract 20% remains intravascular at 1 hour Common in drug preparations 154mmol/L Na and Cl

39 %Saline Na+ Plasma Cl-

40 Remember Drug Infusions! Soluble paracetamol up to mmol Na+ per day Vancomycin 1g in 250ml BD NaCl 0.9% = 77mmol sodium/day Benzylpenicillin 1.2g in 100ml QDS NaCl 0.9% = 75mmol sodium/day Piperacillin/tazobactam 4.5g in 50ml TDS NaCl 0.9% =51.3mmol sodium/day

41 Balanced Solutions 4 large observational studies and a single centre quality improvement initiative have demonstrated associations and superior clinical outcomes and specifically lower incidence of AKI and mortality when compared to isotonic sodium chloride Shaw et al: major complications, mortality and resource utilization after open abdominal surgery Less electrolyte disturbance Fewer acidosis investigations Fewer blood transfusions Less renal failure requiring RRT in ITU Fewer interventions Less postoperative infection

42 Balanced Solutions Hartmanns/Compound Sodium Lactate/Ringers Behaves as sodium chloride 0.9% in distribution Electrolyte content mimics ECF Is isotonic (ph 6.7) 131mmol Na +, 5mmol K +, 2mmol Ca 2+, 111mmol Cl - per litre Plasmalyte- chloride 98 mmol Used for replacing fluid losses from stoma/diarrhoea, hypovolaemia due to blood loss, fluid maintenance Lactate is metabolised and acts as a buffer to acidosis

43 Glucose 4%/Sodium Chloride 0.18% Isotonic solution that provides 160kcal/L 20% sodium chloride and 80% free water Useful where fluid depletion from all compartments eg diabetes insipidus Licensed for sc administration Useful for maintenance but should not be used for resuscitation or replacement Risk of hyponatraemia, especially in the elderly

44 Sodium Bicarbonate Available as 1.26%, 1.4%,1.8%, 2.7% 4.2% and 8.4% Isotonic (1.26%) used to correct acidosis assoc. With renal failure or to induce forced alkaline diuresis. Hypertonic (8.4%) used to raise ph>7.0 in severe acidosis. 8.4% is 1mmol/ml Na+ and HCO3- Metabolic acidosis to restore ph

45 Colloids Substances with large molecular weights which contribute to oncotic pressure at the microvascular endothelium Confined to the plasma? Produce a greater expansion of plasma (by attracting H 2 O from the ICF) Efficacy depends on shape size charge of the molecule porosity of capillary endothelium Unsuitable for treatment of dehydration

46 Blood and blood products Whole blood used to replace the loss of whole blood and to restore Hb Packed red blood cells improve oxygen carrying capacity of blood while preventing fluid overload Fresh frozen plasma not used as a first choice volume expander in shock - usually reserved for multiple coagulation defects, rapid reversal of warfarin, selected immunodeficiencies

47 Colloids Gelatins Derived from animal gelatin (bovine) Wide variation in molecule size Gelofusin succinylated gelatin (4.5%) Cheap. Provides good initial volume expansion Stimulates histamine release Has plasma t 1/2 of 2-4 hours. Intravascular persistence is low?risk of bleeding due to dilution of clotting factors Sodium content of gelofusine-154 mmol/l

48 Esterified starches (hydroxyethyl starch) 4 products diff molecular wt Voluven, EloHaes, HAES-steril, Hemhes Plasma t 1/2 of 24 hours so remain in the body for prolonged periods. Can cause hypersensitivity reactions inc itching CHEST 2012

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52 The Crystalloid versus Hydroxyethyl Starch Trial (CHEST, 2012) Blinded administration of up to 50 ml/kg body weight/day HES versus sodium chloride in adult patients requiring fluid resuscitation in ICU The primary endpoint of all-cause mortality at 90 days was 17% in the sodium chloride 0.9% group and 18% in the HES group. Secondary endpoints revealed an association between HES use and acute kidney injury and a 21% relative risk increase for renal replacement therapy Reinforced by CRISTAL 2013

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57 Human Albumin Solution (HAS) Prepared from whole blood Contains soluble proteins and electrolytes but no clotting factors Can be given without regard to recipients blood group Suspended in 0.9% sodium chloride Available as isotonic (4.5%) and hyperoncotic (20%) 500mls of 4.5% for each 2-3 L ascites drained

58 Albumin Cochrane review RCTs For hypovolaemia no evidence of reduction in mortality with albumin Annals Internal Medicine trials, 3000 patients No effect on mortality Wilkes Ann Int Med 2001;135:

59 SOAP study - observational Sepsis albumin may not be safe in all situations. Trauma.

60 The Saline versus Albumin Fluid Evaluation (SAFE) Study 7000 adults in 16 ICUs in Australia & NZ Blinded RCT: 4% albumin vs. normal saline No significant difference in 28 day mortality The SAFE Study Investigators. N Engl J Med 2004;350:

61 ALBIOS

62 20 % ALbumin Expands 1-1.4x more than 4.5% for a given volume Therefore can use much smaller volumes with a lower sodium load Very expensive Allergic reactions- rare Leaks into interstitium 20% can be resuscitation fluid in hypernatraemia

63 NICE Fluid Guidelines

64 5 RS RESUSCITATION ROUTINE MAINTENANCE WATER AND ELECTROLYTES REPLACEMENT AND REDISTRIBUTION REASSESSMENT

65 4 phases of IV Fluid Therapy Hoste et al 2014

66 RESUSCITATION

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68 Assessment of Hypovolaemia Acute circulatory failure Evidence of fluid loss Early phase of sepsis Yes NO Fluid administration Fluid challenge (mini) Passive leg raising test Cardiac monitoring

69 ac.uk/pages/fluid-therapy

70 Fluid Responsiveness Is defined as increase in stroke volume or cardiac output by a fluid challenge or preferable passive leg raising to increase venous return. Incorporation of this strategy into decision making on fluid loading, even in a patient in shock may help to prevent potentially harmful overhydration

71 Raised leg Test

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74 Pros and cons of crystalloid leading to under or over resuscitation in clinical practice Too Little Tissue hypoxygenation Risk of AKI Lactate and unmeasured anion acidosis Gastrointestinal disturbances Too Much Tissue oedema and hypoxygenation Compartment syndromes and renal dysfunction Hyperchloremic metabolic acidosis and risk of hypernatremia Anastomotic leakage, diarrhoea and other GI disturbances Pulmonary odema, hepatic congestion and injury Prolonged mechanical ventilation

75 MAINTENANCE

76 REPLACEMENT and REDISTRIBUTION

77 REASSESSMENT Step down? Oral route available yet?

78 REFERENCES (abridged) NICE guidelines and elearning available at British consensus guidelines on intravenous fluid therapy for adult surgical patients GIFTASUP available at NHS Fife Fluid Guidelines 2014 available at IVguide2014forintranet2.pdf A comparison of albumin and saline for fluid resuscitation in the intensive care unit. The SAFE study investigators. N engl J med 2004; 350: Hydroxyethyl starch or saline for fluid resuscitation in intensive care. Myburgh et AL N engl J med 2012, 367: Intravenous Fluid therapy in adult inpatients. Frost. BMJ 2014; 350:g7620 Crystalloid fluid therapy. Reddy et al. Critical Care 2016; 20:59 Human albumin solution for resuscitation and volume expansion in critically ill patients. Cochrane Database of Systematic Reviews 2011, Issue 11. Art. No.: CD

79 REFERENCES (abridged) Four phases of intravenous fluid therapy: a Conceptual model. Hoste et al. BJA, 2014; 1-8. Fluid therapy in critical illness. Edwards and Mythen. Extreme Physiology and Medicines 2014; 3:16 Fluid Management for Critically Ill Patients: A Review of current state of fluid therapy in the Intensive Care Unit. Frazee and Kashani. Kidney dis 2016; 2:64-71 Resuscitation Fluids. Myburgh and Mythen. NEJM, 2013; 13: Choices in fluid type and volume during resuscitation:impact on patient outcomes. Lira and Pinksy. Annals of Intensive Care, 2014; 4:38. Rational fluid management in todays ICU practice. Bartels et al. Critical Care 2013; 17(suppl 1):S6 Critical Care Medicine at a glance. Third Edition. R Leach Wiley Blackwell. Chichester.

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