Fluid and electrolytes


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surgeon's approach in fluid management

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Fluid and electrolytes

  1. 1. Fluid and Electrolytes in Surgical Management
  2. 2. Water in Human body • Adult male has 60% of lean body weight as water. • While in females its 50% of lean body weight and in new born its 80%. Total Body Water = 0.6 >< Lean Body Weight (in male) 0.5 >< Lean Body Weight (in female) • Muscles & solid organ contain more water and fat & bone almost lack water.
  3. 3. Compartmental water distribution • Extra cellular 1/3 20% Plasma 80% Interstitium • Intra cellular 2/3
  4. 4. Physiology of body fluids • Osmolarity =2 Na+ + Glucose/18 + BUN /2.8 • Approximately 2 liter of fluid intake daily intake 75% oral water 25% food Daily 3-5 g salt • Out put 1 liter in urine 250 ml stool 600ml insensible loss from lung and skin A minimum of 500ml urine daily
  5. 5. For the ‘average’ 70 Kg man Total body water is 42 L (~60% of body weight) 28 L is in the intracellular and 14 L in the extracellular compartments The plasma volume is 3 L The extravascular volume is 11 L Total body Na+ is 4200 mmol (50% in ECF) Total body K+ is 3500 mmol (only about 50-60 mmol in ECF) Normal osmolality of ECF is 280 –295 mosmol/kg
  6. 6. Maintenance requirements Daily maintenance fluid requirements vary between individuals. 70 Kg male = 2.5 - 3.0L water, 120 – 140 mmol sodium and 70 mmol potassium 40 Kg woman = 2.0L water, 70 – 90 mmol sodium and 40 mmol potassium children 0-10 kg is 100 ml/kg 10-20 kg is 1000 ml + 50 ml/kg for each kg > 10 >20 kg is 1500 ml + 25 ml/kg for each kg > 20
  7. 7. Volume deficit 1. Naso gastric suction 2. Vomiting 3. Diarrhea 4. Fistula 5. Burn 6. Peritonitis 7. Soft tissue injury 8. Intestinal obstruction 9. Prolonged surgery
  8. 8. Features of volume deficit 1. Weight loss 2. Decreased skin turgor 3. Tachycardia 4. Hypotension 5. Collapsed vein 6. Oliguria
  9. 9. Volume excess 1. Iatrogenic 2. Renal dysfunction 3. Congestive heart failure 4. Cirrhosis
  10. 10. Features of volume excess 1. Weight gain 2. Peripheral edema 3. Increased central venous pressure 4. Distended neck veins 5. Murmur 6. Pulmonary edema
  11. 11. Electrolyte imbalance • Hyper nateremia • Hypo nateremia • Hyper kalemia • Hypo kalemia
  12. 12. Hyper nateremia • Causes: A. Hyper volemic 1. Iatrogenic overloading with Na containing fluids. 2. Excess mineralocorticoid B. Normo volemic 1. Renal (Diabetes insipidus,diuretic and renal disorders) 2. Non renal (GI losses and skin) C. Hypo volemic 1. Renal (Diabetes insipidus, adrenal failure, osmotic diuretics and Renal tubular disorders) 2. Non renal (Fever, tracheostomy, diarrhea)
  13. 13. Correction • Calculate water deficit = serum Na -140 >< Total body water 140 D5%, D 5% in 0.25% NS Cerebral edema, herniation
  14. 14. Hyponatremia• Causes: 1. Fluid overload a. Iatrogenic over administration of hypotonic fluids b. Excess oral intake of water or hypotonic fluids c. Drugs like Tricyclic antidepressant, antipsychotics and ACE inhibitors d. Post operative patients due to high ADH. 2. Fluid depletion a. Decreased sodium intake b. GI losses like vomiting, diarrhea, nasogastric suction c. Renal loss- high urinary sodium Features of dehydration 3. Excess solutes a. Hyper glycemia b. Excess mannitol administration 4. Pseudo hyponatremia a. Hyper lipidemia b. Hyper proteinemia
  15. 15. Correction • Calculate Na+ deficit Deficit = (140- Serum sodium) >< TBW Correct 0.5mEq/L to 12 mEq/L in a day Fast correction can lead to Pontine myelinosis
  16. 16. Hyper kalemia Causes A. Increased intake a. Supplements b. Transfusion c. Hemolysis d. Rhabdomyolysis e. Crush injury f. GI hemorrhage B. Increase release by intact cells a. Acidosis b. Alteration in extracellular osmolarity C. Impaired secretion a. Potassium sparing diuretics b. Renal failure
  17. 17. ECG features 1. Peak T wave 2. Flat P wave 3. PR prolongation 4. QRS prolongation 5. Sine wave
  18. 18. Correction 1. Cation exchange resin, kayexalate 2. Glucose and HCO3-, Glucose Insulin 3. If ECG changes occur, Ca++ Cl- 4. Beta agonist 5. Dialysis
  19. 19. Hypo kalemia Causes A. Decreased intake a. K+ free fluids B. Increase loss a. Hyper aldosterone b. Diuretics C. GI loss a. Diarrhea b. Vomiting c. RT aspirate
  20. 20. ECG changes 1. U wave 2. T wave 3. ST segment changes Correction a. Potassium deficit in mmol is calculated as given below: Kdeficit (mmol) = (Knormal lower limit - Kmeasured) x kg body weight x 0.4 b. Daily potassium requirement is around 1 mmol/Kg body weight. c. 13.4 mmol of potassium found in 1 g KCl. (molecular weight KCl = 39.1 + 35.5 = 74.6)
  21. 21. Composition of crystalloids • 3L of Dextrose saline is not equivalent to 2L 5% Dextrose and 1L Normal saline • 3L Dextrose Saline = 3L water and 90 mmol sodium • 2L 5% Dextrose saline + 1L Normal saline = 3L water and 154 mmol sodium Hartmann’s Solution Normal Saline Dextrose Saline Sodium (mmol/ l) 131 150 30 Chloride (mmol/l) 111 150 30 Potassium (mmol/l) 5 Nil Nil Bicarbonate (mmol/l) 29 Nil Nil Calcium (mmol/l) 2 Nil Nil
  22. 22. Normal saline • 154 mEq/L Disadvantages • Cl- overload • Hyper chloremic metabolic acidosis Advantages • Hypo natremia • Hypo chloremia
  23. 23. Ringer lactate • Contain lactate gets converted to HCO3-in liver. • Advantage Physiological fluid • Disadvantage D isomer shows inflammatory response
  24. 24. Colloids • Stay in intravascular compartment for long time. • Disadvantages Detrimental in severe hemorrhagic shock when capillary permeability is high it may worsen edema
  25. 25. Composition of colloids Volume effect (%) Average MW (kDa) Circulatory half life Gelatins (Haemaccel) 80 35 2-3 hours 4% Albumin 100 69 15 days Dextran 70 120 41 2-12 hours 6% Hydroxyethyl Starch 100 70 17 days • Monodispersed = All molecules of similar molecular weight • Polydispersed = Molecules have spread of molecular weights
  26. 26. Albumin • Monodispersed • Sterlized pooled human plasma • Expensive • May worsen renal failure, pulmonary edema and cause hypersensitivity. • Long half life • Accounts for 60-80% of normal plasma oncotic pressure • No adverse effect on coagulation
  27. 27. Dextrans • Polysaccharides • Bacteria grown on sucrose medium • Polydispersed with MW 10-90 kDa • Reduces plasma viscosity • Reduces platelet aggregation • 1-5% develop anaphylaxis
  28. 28. Gelatins • Polypeptides • Bovine collagen • Not approved in US • Polydispersed with MW ~35 kDa • Rapidly lost from vascular space Hydroxyethyl starch • Synthetic polysaccharide polymers derived from amylopectin • Polydispersed with MW 50-450 kDa • Large molecules engulfed by reticuloendothelial system • Associated with bleeding diathesis, renal dysfunction and hyperchloremic acidosis
  29. 29. Assessment of adequacy of resuscitation • Clinical history and observations – Pulse, blood pressure, skin turgor • Urine output – oliguria < 0.5 ml/kg/hr • CVP or pulmonary capillary wedge pressure • Response of urine output or CVP to fluid challenge • A fluid challenge should be regarded as a 200-250 ml bolus of colloid • This should be administered as quickly as possible • A response in the CVP or urine output should be seen within minutes • The size and duration of the CVP response rather the actual values recorded is more important
  30. 30. GIFTASUP Recommendations (2008) Guidelines for Intravenous Fluid Therapy for Adult Surgical Patients Preoperative fluid management Recommendation 4 In patients without disorders of gastric emptying undergoing elective surgery clear non-particulate oral fluids should not be withheld for more than two hours prior to the induction of anaesthesia Recommendation 5 In the absence of disorders of gastric emptying or diabetes, preoperative administration of carbohydrate rich beverages 2-3 h before induction of anaesthesia may improve patient well being and facilitate recovery from surgery. It should be considered in the routine preoperative preparation for elective surgery Recommendation 6 Routine use of preoperative mechanical bowel preparation is not beneficial and may complicate intra and postoperative management of fluid and electrolyte balance. Its use should therefore be avoided whenever possible Recommendation 7 Where mechanical bowel preparation is used, fluid and electrolyte derangements commonly occur and should be corrected by simultaneous intravenous fluid therapy with Hartmann’s or Ringer-Lactate/acetate type solutions
  31. 31. Recommendation 8 Excessive losses from gastric aspiration or vomiting should be treated preoperatively with an appropriate crystalloid solution which includes an appropriate potassium supplement. Hypochloraemia is an indication for the use of 0.9% saline, with sufficient additions of potassium and care not to produce sodium overload. Losses from diarrhoea, ileostomy, small bowel fistula, ileus or obstruction should be replaced volume for volume with Hartmann’s or Ringer-Lactate/acetate type solutions. “Saline depletion,” for example due to excessive diuretic exposure, is best managed with a balanced electrolyte solution such as Hartmann's Recommendation 9 In high risk surgical patients, preoperative treatment with intravenous fluid and inotropes should be aimed at achieving predetermined goals for cardiac output and oxygen delivery as this may improve survival Recommendation 10 Although currently logistically difficult in many centres, preoperative or operative hypovolaemia should be diagnosed by flow-based measurements wherever possible. The clinical context should also be taken into account as this will provide an important indication of whether hypovolaemia is possible or likely. When direct flow measurements are not possible, hypovolaemia will be diagnosed clinically on the basis of pulse, peripheral perfusion and capillary refill, venous pressure and Glasgow Coma Scale together with acid-base and lactate measurements. A low urine output can be misleading and needs to be interpreted in the context of the patient’s cardiovascular parameters above
  32. 32. Recommendation 11 Hypovolaemia due predominantly to blood loss should be treated with either a balanced crystalloid solution or a suitable colloid until packed red cells are available. Hypovolaemia due to severe inflammation such as infection, peritonitis, pancreatitis or burns should be treated with either a suitable colloid or a balanced crystalloid. In either clinical scenario, care must be taken to administer sufficient balanced crystalloid and colloid to normalise haemodynamic parameters and minimise overload. The ability of critically ill patients to excrete excess sodium and water is compromised, placing them at risk of severe interstitial oedema. The administration of large volumes of colloid without sufficient free water (e.g. 5% dextrose) may precipitate a hyperoncotic state Recommendation 12 When the diagnosis of hypovolaemia is in doubt and the central venous pressure is not raised, the response to a bolus infusion of 200 ml of a suitable colloid or crystalloid should be tested. The response should be assessed using the patient’s cardiac output and stroke volume measured by flow-based technology if available. Alternatively, the clinical response may be monitored by measurement/estimation of the pulse, capillary refill, CVP and blood pressure before and 15 minutes after receiving the infusion. This procedure should be repeated until there is no further increase in stroke volume and improvement in the clinical parameters
  33. 33. Intraoperative fluid management Recommendation 13 In patients undergoing some forms of orthopaedic and abdominal surgery, intraoperative treatment with intravenous fluid to achieve an optimal value of stroke volume should be used where possible as this may reduce postoperative complication rates and duration of hospital stay Recommendation 14 Patients undergoing non-elective major abdominal or orthopaedic surgery should receive intravenous fluid to achieve an optimal value of stroke volume during and for the first eight hours after surgery. This may be supplemented by a low dose dopexamine infusion
  34. 34. Postoperative fluid, and nutritional management Recommendation 15 Details of fluids administered must be clearly recorded and easily accessible Recommendation 16 When patients leave theatre for the ward, HDU or ICU their volume status should be assessed. The volume and type of fluids given perioperatively should be reviewed and compared with fluid losses in theatre including urine and insensible losses Recommendation 17 In patients who are euvolaemic and haemodynamically stable a return to oral fluid administration should be achieved as soon as possible
  35. 35. Recommendation 18 In patients requiring continuing i.v. maintenance fluids, these should be sodium poor and of low enough volume until the patient has returned their sodium and fluid balance over the perioperative period to zero. When this has been achieved the i.v. fluid volume and content should be those required for daily maintenance and replacement of any on-going additional losses Recommendation 19 The haemodynamic and fluid status of those patients who fail to excrete their perioperative sodium load, and especially whose urine sodium concentration is <20mmol/L, should be reviewed Recommendation 20 In high risk patients undergoing major abdominal surgery, postoperative treatment with intravenous fluid and low dose dopexamine should be considered, in order to achieve a predetermined value for systemic oxygen delivery, as this may reduce postoperative complication rates and duration of hospital stay
  36. 36. Recommendation 21 In patients who are oedematous, hypovolaemia if present must be treated, followed by a gradual persistent negative sodium and water balance based on urine sodium concentration or excretion. Plasma potassium concentration should be monitored and where necessary potassium intake adjusted Recommendation 22 Nutritionally depleted patients need cautious refeeding orally, enterally or parenterally, with feeds supplemented in potassium, phosphate and thiamine. Generally, and particularly if oedema is present, these feeds should be reduced in water and sodium. Though refeeding syndrome is a risk, improved nutrition will help to restore normal partitioning of sodium, potassium and water between intra and extra-cellular spaces Recommendation 23 Surgical patients should be nutritionally screened, and NICE guidelines for perioperative nutritional support adhered to. Care should be taken to mitigate risks of the refeeding syndrome