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Common fluids used in anaesthesia and fluid therapy

common fluids used in anaesthesia. fluid therapy in anaesthesia and theatre. emergency fluid replacement. calculation of fluid by anaesthetist. colloids and crystalloids, indication in anaesthesia

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Common fluids used in anaesthesia and fluid therapy

  1. 1. COMMON FLUIDS USED IN ANAESTHETIC PRACTICE/FLUID THERAPYIN ANAESTHESIA BY AROWOJOLU BOLUWAJI SAMUEL
  2. 2. INTRODUCTION Intravenous (IV) fluids are chemically prepared solutions that are tailored to the body’s needs and used to replace lost fluid and/or aid in the delivery of intravenous medications (Perel, 2012) Safe and effective prescribing of intravenous fluids requires understanding of the physiology of fluid and electrolyte homeostasis, physiological responses to injury and disease, as well as knowledge of the properties of intravenous fluids
  3. 3. INTRODUCTION CONT’D Starvation, surgery and anaesthesia cause stress and alter body physiology Intravenous fluids are administered perioperatively to maintain homeostasis during this period
  4. 4. • Explain the distribution of fluids in various body compartments • Explain the concept of intravenous fluid therapy • Explain the principles and protocols involved in fluid therapy • Describe the forms of intravenous fluids and their compositions
  5. 5. Distributionof Fluidsin DifferentBody Compartments Total Body Water =60% of body weight (42 litres) Plasma component = 5% (3 litres) Extracellular Compartment = 20% (14 litres) It is rich in Na+ and CI- Intracellular compartment = 40% (28 litres). high in KPO4 3- Interstitial Fluid component = 15% (11 litres)
  6. 6. ECF is high in Na+ and Cl- while ICF is high in KPO4 3-. Water without sodium expands the TBW All infused Na+ remains in the ECF via the Na+ pump. Hence, normal saline expands the ECF only There is a fine balance between input, controlled by the thirst mechanisms and output that is controlled mainly by the renals (ADH system)
  7. 7. BasicfluidHomeostasis Routes Average Daily Volume (ml) Total intake H2O intake: Sensible 2500 Oral fluids 800 – 1500 Solid foods 500 – 700 Insensible: Water of metabolism 250 H2O loss Sensible: 2500 Urine 800 – 1500 Intestinal 150 – 400 Sweat 150 Insensible: Lungs and skin 600
  8. 8. DailyElectrolyte Requirements Electrolyte Daily requirement For 70Kg adult For 10Kg Child Sodium 1 – 2 meq/kg 70 – 140 meq/day 10 – 20 meq/day Potassium 0.5 – 1.0 meq/kg 35 – 70 meq/day 5 – 10 meq/day Calcium 0.2 – 0.3 meq/kg 1.4 – 2.1 meq/day 2.0 – 3.0 meq/day Magnesium 0.35 – 0.45meq/kg 24.5 – 31.5 meq/day 3.5 – 4.5 meq/day Chloride Equal to sodium Equal to sodium Equal to sodium Bicarbonate/Acetate Use with chloride to balance cations and help PH Use with chloride to balance cations and help PH Use with chloride to balance cations and help PH
  9. 9. Concepts of Intravenous Fluid Therapy There are 3 key concepts namely: 1. Cell membrane permeability 2. Osmolarity. Concentration of sodium is the major determinant of osmolarity. Normal serum osmolarity ranges from about 280 to 295 mOsm 3. Electroneutrality
  10. 10. Goals of FluidManagement Principle goals: Maintain intravascular volume Maintain cardiac preload Maintain adequate blood pressure Replace insensible and surgical losses Ultimate goal is optimizing oxygen delivery
  11. 11. Indications for fluid administration in anaesthetic practice 1. Preoperative fasting 2. Surgical blood loss 3. Urinary excretion 4. Vasodilation caused by anesthesia e.g during epidural anesthesia 5. Transfer to third space 6. Transcapillary leak of albumin caused by inflammatory mediators 7. Hypotension 8. Hypovolemia 9. Electrolyte, metabolic and acid base disorders 10.Geriatric patients at risk of organ failure
  12. 12. Forms of Intravenous Fluids Colloids Crystalloids Blood and blood products Oxygen carrying solutions
  13. 13. Colloids solutions • Colloid solutions are IV fluids that contain solutes in the form of large proteins or other similarly sized molecules. • Colloids remain in the blood vessels for long periods of time and can significantly increase the intravascular volume (volume of blood) • Colloids are expensive and have a short shelf life. Commonly used colloid solutions include salt poor albumin, dextran and hetastarch (Hespan, Voluven)
  14. 14. Colloids are always administered along with crystalloids to restore both intravascular and interstitial fluid volume. Indications: hypoproteinemia, decreased oncotic pressure and increased capillary pore size in conditions associated with sepsis or systemic inflammatory response syndrome. Whenever a colloid is administered with a crystalloid, reduce the calculated crystalloid fluid requirements by 25% to 50% to avoid volume overload Types of colloids are : Natural colloids and synthetic colloids
  15. 15. Natural colloid solutions include whole blood and plasma The Rule of Ones states that 1 ml fresh blood infused per 1 lb body weight (2.2 ml/kg) will increase a patient's packed cell volume (PCV) by 1%, provided no ongoing losses are present A more accurate method to determine the volume of whole blood to administer is as follows: ml donor blood needed = [(Desired PCV – Actual Recipient PCV) ÷ Donor PCV] × ml recipient blood volume
  16. 16. Synthetic Colloids Hydroxyethyl Starch (Hetastarch)  It is synthesized from amylopectin  It last in circulation for 36 hours  Administer at 5 – 7 ml/kg as a bolus dose  The total daily dose of hetastarch should not exceed 20 to 30 ml/kg/day  Rapid hetastarch administration can cause histamine release & vomiting, administer the bolus slowly over 15 to 20 minutes  It may cause renal dysfunction
  17. 17. Synthetic Colloids cont’d Dextran:  It contains polymers of glucose with average molecular weights of 40 and 70 daltons  Dextran 70 is preferred to dextran 40 cos dextran 70's larger particles contribute to the water-holding capacity of blood  It last between 4 – 9 hours  Anaphylaxis and renal failure have been reported in people that received dextran 40  The dose is 10 to 20 ml/kg/day given intravenously
  18. 18. Polymerized bovine hemoglobin glutamer-200  It contains bovine stoma-free hemoglobin that acts both as a potent colloid and as an oxygen carrier in the face of thrombosis or anemia  Recommended doses are 20 to 30 ml/kg/day  Administered as an intravenous bolus of 3 to 7 ml/kg
  19. 19. Human Serum Albumin  It is a purified human protein gotten from plasma  90% of it remains intravascular after about 2 hours of administration  Albumin contributes 80% of the oncotic pressure of blood & acts as a carrier for various essential compounds in the body  It is effective in restoring serum & interstitial albumin in patients with acute or chronic hypoalbuminemia  Patients with conditions associated with increased capillary pore size, such as sepsis, vasculitis & systemic inflammatory response syndrome can benefit from maintaining the serum albumin concentration at or ideally above 2 g/dl
  20. 20. Crystalloid Solutions Crystalloid solutions are the primary fluid used for anaesthetic IV therapy. They contain electrolytes but lack the large proteins and molecules found in colloids. They are classified based on their tonicity: Hypertonic, Hypotonic & Isotonic Examples are 0.9% normal saline, Lactated Ringer’s and plasmalyte. For every 1 liter of blood lost, 3 liters of an isotonic crystalloid be administered for replacement
  21. 21. ISOTONIC FLUIDS Examples are 0.9%NS, Lactated Ringer’s & plasmalyte Indications: to restore fluid deficits, correct electrolyte abnormalities & provide maintenance fluid requirements. Side effects: mild hypernatremia HYPERTONICFLUIDS Examples are 1.8%, 3%, 5%, 7%, 7.5%, 10% saline They are considered as plasma expanders as they act to increase the circulatory volume via movement of intracellular & interstitial water into the intravascular space Administering a low- sodium crystalloid fluid after a hypertonic saline solution can lead to interstitial edema HYPOTONICFLUIDS Examples are 0.45%NaCl, 0.45% NaCl+2.5% Dextrose & 5% DW. Indications: treating patients with disease processes that cause Na & H2O retention, namely, congestive heart failure, hepatic disease., severe hypernatremia
  22. 22. The most common isotonic solutions used in anesthetic management are: Lactated Ringer’s: contains sodium chloride, potassium chloride, calcium chloride, and sodium lactate in sterile water. avoided if hyperkalemic or hypercalcemic as it tends to induce mild alkalosis Normal saline solution: contains 0.9% Nacl (salt) in sterile water. It is useful if patient is hyperkalemic, hyponatremic, hypochloremic or if slight hyperosmolarity is desired. 5% Dextrose in water: contains glucose (sugar) as the solute. It is seldom used in anesthetic practice but very useful as a background maintenance for diabetics on insulin, children and adults undergoing long cases (> 6 – 8 hours)
  23. 23. 3. Blood and Blood Products  Examples are platelets, packed red blood cells, whole blood & plasma  Unlike colloids and crystalloids, the hemoglobin (in the red blood cells) carries oxygen to the cells.  Not only is the intravascular volume increased, but the fluid administered can also transport oxygen to the cells 4. Oxygen-Carrying Solutions  Oxygen-carrying solutions are synthetic fluids that carry and deliver oxygen to the cells.  These fluids, which remain experimental has showed promise for anesthetic care of patients who have experienced severe blood loss or are otherwise suffering from hypovolemia
  24. 24. Principles and protocols for intravenous fluidtherapy 4Rs Fluid resuscitation Routine maintenance Replacement Redistribution Swollen… what’s the big deal
  25. 25. Solution PH Na+ Cl- K+ Ca2+ Other components Comments Ringers Lactate (LR) 130 109 4 3 Lactate 28 meq/L Fluid choice for initial resuscitation. Normal Saline (NS) 154 154 0 0 Alternative to LR; watch for hyper-chloremic acidosis D5LR 5 130 109 4 3 Dextrose 50g, Lactate 28 meq/L Initial postoperative maintenance; caution blousing with dextrose D5NS 4 154 154 0 0 Dextrose 50g Alternative to D5LR D5,45NS 4 77 77 0 0 Dextrose 50g Hypotonic maintenance D5,25NS 4 34 34 0 0 Dextrose 50g Hypotonic maintenance 7.5% NS 4 1283 1283 0 0 0 Hypertonic D5W 4.5 0 0 0 0 Dextrose 50g Free water; no role in resuscitation 6% hetastarch 3.5 – 7.0 154 154 0 0 30g hydroxyethyl starch Coagulation abnormalities 5% plasma protein (250ml) 7.4 145 0 <2 0 12.5g protein Colloid expensive Composition of common IV fluids
  26. 26. The percentage of dehydration can be subjectively estimated based on the presence and degree of loss of body weight, mucous membrane dryness, decreased skin turgor, sunken eyes, and altered mentation Severe hypovolemia resulting in more than a 15% depletion of effective circulating volume leads to a transcompartmental fluid shift from the interstitial to the intravascular compartments, which occurs within one hour of fluid loss During states of normovolemia, baroreceptors in the carotid body and aortic arch sense vascular wall tension and send pulsatile continuous feedback via vagal afferent stimuli to decrease heart rate ClinicalAssessment of dehydration
  27. 27. • In the early stages of hypovolemic shock, the baroreceptors sense a decrease in vascular wall stretch or tension and blunt the tonic vagal stimulation • This allows sympathetic tone to increase heart rate and contractility in an attempt to normalize cardiac output • Dehydration can be graded into mild, moderate, severe and shock based on the percentage of fluid lost. ClinicalAssessment of dehydration cont’d
  28. 28. Grade % of fluid lost Clinical Signs and Symptoms Mild 5% Increased thirst, tears present, mucous membranes moist, ext. jugular visible when supine, capillary refill > 2 seconds centrally, urine specific gravity > 1.020 Moderate 10% Tacky to dry mucous membranes, decreased tears, pulse rate may be elevated somewhat, fontanel may be sunken, oliguria, capillary refill time between 2 and 4 seconds, decreased skin turgor Severe 15% Tears absent, mucous membranes dry, eyes sunken, tachycardia, slow capillary refill, poor skin turgor, cool extremities, orthostatic to shocky, apathy, somnolence Shock >15% Physiologic decompensation: insufficient perfusion to meet end- organ demand, poor oxygen delivery, decreased blood pressure.
  29. 29. Combined water and electrolyte deficit is commonly associated with GIT losses, diuretic therapy, adrenal insufficiency, excessive diaphoresis, burns, stomas and third spacing following trauma or surgery Treatment involves replacement of enough water to restore plasma [Na+] to normal The excess sodium for which water must be provided can be estimated from the equation: change in Na = (140 – Na plasma) x TBW (Recall TBW = ECF + ICF = 50 to 70% body weight) Pure water deficit is reflected biochemically by hypernatremia, increase in plasma osmolality, concentrated urine and low urine [Na+] (<15mEq/L)
  30. 30. Colloids versus Crystalloids for Resuscitation • Controversy exists over the use of colloids and crystalloid solutions as resuscitative fluids. The large volumes of crystalloid sometimes necessary to stabilize patients may lead to peripheral edema that may impair wound healing. • Colloids offer the theoretical advantage of expanding the intravascular space with less volume and have been shown to increase blood pressure more rapidly than crystalloids • 1litre of dextran increases intravascular volume by 800ml; 1 L of hetastarch by 750ml; 1L 5% albumin by 500mls; and 1L normal saline by 180 mls
  31. 31. Colloids may inhibit the coagulation system and cause anaphylactoid reaction. Overall meta-analyses of IVF therapy have not supported a benefit for colloids over crystalloids. Several meta-analyses have shown a trend toward increased mortality in heterogeneous groups of critically ill patients resuscitated with colloids. crystalloids still remain the cornerstone of volume resuscitation, although patients with profound volume deficits may benefit from colloids in addition to crystalloids Colloids versus Crystalloids for Resuscitation
  32. 32. FLUID RATE CALCULATIONS 3 elements to be considered include:  Replacement  Maintenance  Ongoing losses Replacement IVF: They are calculated based on the level of dehydration. Amount required for replacement within a 24 hour period include: Replacement = % Dehydration x Body Weight (kg) x 10
  33. 33. MaintenanceIVF:  Holliday-Segar method (4-2-1) is the most commonly used.  Fluid and electrolyte requirements are empirically based on caloric needs of the average hospital patient.  This caloric expenditure is approximated based on body weight. For each kilogram in this range Hourly Maintenance Fluid Requirements 1-10 kg (1st 10kg) 4ml/kg/hr 11-20 kg (2nd 10kg) 40ml + 2ml/kg/hr for each kg over 10 >20 kg 60ml + 1ml/kg/hr for each kg over 20
  34. 34. Ongoing losses: It is calculated based on a predicted amount of fluid lost by a patient within a 24 hour period. Ongoing losses = Amount per loss (ml/kg) x Body Weight (kg) x No. of losses. This is then further calculated depending on whether a drip pump is used or fluid rate is adjusted manually as shown below. Requirement per hour (ml/hr) = requirement per day (ml/24hr) ÷ 24
  35. 35. Special Consideration in Fluid Therapy 1. Shock • Signs include tachycardia, pale mucous membrane, prolonged/absent capillary refill time, hypotension, reduced/absent peripheral pulses. • Forms include: Hypovolemic, cardiogenic, Vascular: Obstructive, distributive • Choice of fluid in hypovolemic shock is isotonic crystalloid fluid. • Cardiogenic shock is diuretic cos the patient is already in volume overload • Obstructive shock is often treated by removal of the obstruction. is defined as decreased oxygen delivery or utilization by tissues that may lead to irreversible cellular damage if prolonged
  36. 36. 2. Anaesthesia i. Pre-anaesthetic: Stabilize a patient fluid deficits & any electrolyte or acid-base imbalances before anaesthesia. PCV & if possible urea, creatinine, electrolyes and glucose should be balanced. Even if balanced, place the patient on fluids as most anaesthetic agents will alter fluid homeostasis. ii. Intra-anaesthetic: normal homeostatic functions of the patient is are altered during anesthesia & so fluid therapy should be initiated. > Glucose levels should be closely monitored, especially patients with diabetes, liver disease or pediatric patients. > Some patients may develop an anaesthetic-induced hypotension from the side-effects of anaesthetics. Hence, Fluids are given as a preventative measure. > Replace significant blood loss with either blood products or appropriate fluid. > Ensure fluid is warm before administration.
  37. 37. 3. Cardiac Disease  Avoid fluid overload in cardiac patients who often have reduced cardiac function.  This means it is important to closely monitor fluid administration in these patients as it may worsen the patient's condition. 4. Hepatic Disease  Patients with hepatic disease often have alterations in protein levels due to reduced production, as well as changes in clotting factors  Hypoproteinemia will affect patients undergoing anaesthetics as many agents are protein bound so the reduction in protein means that more of the agent may be available  If there are any clotting disorders then it may be necessary to give blood products so that the missing clotting factors are available to the patient, while the underlying cause is diagnosed and treated.
  38. 38. 5. Central Nervous System Disease Patients with head trauma or increased intracranial pressure are particularly susceptible to insufficient or excessive fluid loading The choice of fluid is dependent on the other clinical signs of the patient such as haemodynamics The status of the blood brain barrier is an important consideration in any patient and in the selection of fluid However, fluids containing glucose should be avoided in these patients.
  39. 39. Intravenous Fluid Packaging Most IV fluids are packaged in soft plastic or vinyl bags of various sizes (10, 50, 100, 250, 500, 1,000, 2,000, and 3,000 milliliters) Every IV fluid container must contain a label. The information on the label include: Type of IV fluid (by name and by type of solutes contained within), Amount of IV fluid (expressed in milliliters or “mL”) and Expiration date The IV fluid container contains a medication injection site and administration set port. Both ports are located on the bottom of the IV bag when holding it upright
  40. 40. Conclusion IVF therapy is undoubtedly one of the mainstays of treatment of both acute and chronic illnesses Similar to choosing an antibiotic to treat the most likely bacterial infection, a fluid should be chosen to treat a specific disease entity. The fluid should be chosen after careful consideration of an individual’s acid-base, electrolyte, dehydration, and oncotic pressure status. However, having a combination of replacement and maintenance crystalloids along with a colloid to choose from can decrease morbidity and mortality in your most critically ill patients
  41. 41. SVWY LMNPR FGHIJ ABCDE References

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