Fluid and Electrolyte Balance during Injury

Fluid and Electrolyte Balance during Injury Zohair Al Aseri. MD. FCEM(UK).FRCPC (EM&CCM) Chairman ,National Emergency Medicine Committee Consultant, ICU Department of Critical Care College of Medicine, King Saud University Medical City. Riyadh, KSA. zalaseri@ksu.edu.sa http://fac.ksu.edu.sa/zalaseri

Fluid and Electrolyte Balance during Injury • Objectives • Understand and inflammatory response to surgery and trauma • Understand normal regulation of fluid balance • Fluid Imbalance In Shock State • Fluid Therapy (Types) & Indication • Electrolyte disturbances in trauma and surgery • Acid base in surgery patients

Case 1 39 year old male involved in MVC brought to ED by EMT, he is unconscious, heart rate 120 beat per minute blood pressure of 80/50, intubated in the scene, what is your immediate action • Take further history • Start him on dextrose 5% with NS • Start him in colloid • Start him in Normal saline

Case2 A recovery nurse calling you to see a 70 year old male, 7 hours post appendicictomy, because he is drowsy and unresponsive, his vital signs are normal and oxygen saturation 92% on room air? What is the most likely diagnosis? • Intracranial bleeding • Stroke • Acute renal failure • Respiratory failure

Case3 70 year old male, admitted for elective hernia repair, kept NPO and started in D5 ½ normal saline 24 hour ago, his current electrolyte showed k of 5 mmol and Na of 128 mmol What is the most likely diagnosis? • DI • SAIDH • Acute renal failure • Iatrogenic hyponatremia

Fluid and Electrolyte Balance during Injury FLUID AND ELECTROLYTE BALANCE: May be altered in the surgical patient for several reasons: • Reduced oral fluid intake in the perioperative period • ADH and aldosterone secretion. • Loss from the GI tract (e.g. bowel preparation, ileus, stomas, fistulae). • Reduced oral fluid intake in the perioperative period

Fluid and Electrolyte Balance during Injury FLUID AND ELECTROLYTE BALANCE: • Insensible losses (e.g. sweating secondary to fever). • Third space losses. • Surgical drains. • Medications (e.g. diuretics). • Underlying chronic illness (e.g. cardiac failure, portal hypertension).

Metabolic response to injury, fluid and electrolyte balance and shock • FLUID AND ELECTROLYTE BALANCE: • Careful monitoring of fluid balance and thoughtful replacement of net fluid and electrolyte losses is therefore important in the perioperative period.

Fluid and Electrolyte Balance during Injury Normal water and electrolyte balance: • Water forms about 60% of total body weight in men and 55% in women. • Approximately two-thirds is intracellular, one-third extracellular. • Extracellular water is distributed between the plasma and the interstitial space

Regulation of Fluid Balance TOTAL BODY FLUID (40) liters;60%TBW The intracellular and extracellular compartments are separated by water-permeable cell membranes. Plasma volume (3 liters,5 %) Red cell volume (2 liters) Extracellular (15 liters,20%) Intracellular (25 liters,40%) Blood volume (5 liters)

IC. WATER ECF 2/3 intrest. 1/3 blood 25 150 15 0.01 2 6 50 Na K Mg Ca Cl Hco3 Phos 140 4.5 1.2 2.4 100 25 1.2 Fluid & Electrolyte Balance

Regulation of Fluid Balance ECC Osmolarity ECF Volume Maintain BP Prevent swelling or shrinking of the cells

Fluid and Electrolyte Balance during Injury Osmolality of extracellular fluid • normally 275-295 mOsmol/kg determined primarily by sodium and chloride ion concentrations.

Fluid and Electrolyte Balance during Injury Normal water and electrolyte balance: • Plasma oncotic pressure is primarily determined by albumin.

Fluid and Electrolyte Balance during Injury Normal water and electrolyte balance: • Aldosterone and ADH facilitate sodium and water retention • Atrial natriuretic peptide (ANP), released in response to hypervolaemia and atria distensionstimulates sodium and water excretion.

Fluid and Electrolyte Balance during Injury Normal water and electrolyte balance: In adults, • Normal daily fluid requirement is 30-35ml / kg (-2500 ml /day). In newborn babies and children • Contain proportionately more water than adults. • Daily maintenance fluid requirement at birth is about 75ml/ kg, increasing to 150 ml/ kg during the first weeks of life.

Fluid and Electrolyte Balance during Injury Normal water and electrolyte balance: • After first month of life, fluid requirements decrease and the '4/2/1' formula can be used to estimate maintenance fluid requirements: • first l0 kg of body weight requires 4ml /kg/h; • the next 10kg 2ml /kg/ h; • thereafter each kg of body requires 1ml/kg/h.

Fluid and Electrolyte Balance during Injury The estimated maintenance fluid requirements of a 35 kg child would therefore be: • (10 X 4) + (10 X 2) + (15 X 1) = 75 mljh.150 . • The daily requirement for both sodium and potassium in children is about 2-3mmol/kg.

Fluid and Electrolyte Balance during Injury Assessing losses in the surgical patient:

Metabolic response to injury, fluid and electrolyte balance and shock Normal water and electrolyte balance: • 2500-3000ml of fluid is lost via the kidneys, gastrointestinal tract and through evaporation from the skin and respiratory tract • fluid losses are largely replaced through eating and driniking.

Fluid and Electrolyte Balance during Injury Assessing losses in the surgical patient:

Fluid and Electrolyte Balance during Injury Source of Fluid Loss in Surgical Patients

Metabolic response to injury, fluid and electrolyte balance and shock Normal water and electrolyte balance: • a further 200-300 ml of water is provided endogenously every 24 hours by the oxidation of carbohydrate and fat. • lnthe absence of sweating, almost all sodium loss is via the urine and, under the influence of aldosterone, this can fall to 10-20 mmol/24 hrs.

Metabolic response to injury, fluid and electrolyte balance and shock Normal water and electrolyte balance: • Potassium is also excreted mainly via the kidney with a small amount (10 mmol / day) lost via the gastrointestinal tract.

Metabolic response to injury, fluid and electrolyte balance and shock Normal water and electrolyte balance: • In severe potassium deficiency, losses can be reduced to about 20 mmol/ day, but increased aldosterone secretion, high urine flow rates and metabolic alkalosis all limit the ability of the kidneys to conserve potassium and predispose to hypokalaemia.

Fluid and Electrolyte Balance during Injury Insensible fluid losses: Hyperventilation • increases insensible water loss • is not usually large unless the normal mechanisms for humidifying inhaled air (the nasal passages and upper airways) are compromised. this occurs in intubated patients or in those receiving non humidified high-flow oxygen. • In these situations inspired gases should be humidified routinely.

Fluid and Electrolyte Balance during Injury Insensible fluid losses: Pyrexia • 200ml/day for each 1°C rise in temperature. Sweating • May increase fluid loss by up to 1 litre/hour • Sweat also contains significant amounts of sodium (20-70mmol/l) and potassium (10mmol/l).

Fluid and Electrolyte Balance during Injury The effect of surgery: The stress response • ADH leads to water retention and a reduction in urine volume for 2-3days following major surgery. • Aldosteroneconserves both sodium and water, further contributing to oliguria. • Urinary sodium excretion falls while urinary potassium excretion increases, predisposing to hypokalaemia.

Fluid and Electrolyte Balance during Injury 'Third-space' losses: • if tissue injury is severe, widespread and/or prolonged then the loss of water, electrolytes and colloid particles into the interstitial space can amount to many litres and can significantly decrease circulating blood volume following trauma and surgery.

Regulation of Fluid BalanceQ=K[(Pc-Pi)-@(Oc-Oi)] Arteriole Venule Pnet =(37-1)+(0-25)=11 17 Mm Hg 37 mm Hg Oncotic P=25 Interstitial Hydrostatic P=1 Pnet =(17-1)+(0-25)=-9

Fluid and Electrolyte Balance during Injury 'Third-space' losses: • Colloid oncotic pressure throughout the lumen of the capillary is 25mmHg. • The hydrostatic pressure is 1 mmHg in the interstitium. • Hydrostatic pressure on the arteriolar side of the capillary falls from 37 mmHg to 17 mmHg on the venular side. • net outward pressure on the arteriolar side (37 - 1 - 25 = 11) • net inward pressure (25 -17-1= 9) on the venular side.

tending to move fluid out of the capillaries tending to keep fluid within the capillaries Regulation of Fluid Balance Oncotic pressure Hydrostatic pressure Excess fluid filtered is collected through the lymphatic circulation and returned to the Systemic circulation THE STARLING EQUATION

Fluid and Electrolyte Balance during Injury Third-space' losses: Oedema is formed if • hydrostatic pressure increases on the venular side as in heart failure or • colloid oncotic pressure falls due to liver or kidney disease or • permeability is increased as in sepsis and /or injury.

Fluid and Electrolyte Balance during Injury Loss from the gastrointestinal tract • The magnitude and content of fluid losses depends on the site of loss or lntestinalobstruction. • lngeneral, the higher an obstruction occurs in the intestine, the greater the fluid loss

The approximate daily volumes (ml) and electrolyte concentrations (mmol/l) of various gastrointestinal fluids.

Fluid and Electrolyte Balance during Injury Loss from the gastrointestinal tract Paralytic ileus. • Propulsion in the small intestine ceases, has numerous causes. • Resolves within 1-2days of the operation.

Fluid and Electrolyte Balance during Injury Loss from the gastrointestinal tract: Intestinal fistula • associated with the greatest fluid and electrolyte losses.

Fluid and Electrolyte Balance during Injury Loss from the gastrointestinal tract: Diarrhoea. • Patients may present with diarrhoeaor develop it during the perioperative period. • Fluid and electrolyte losses may be considerable.

Fluid and Electrolyte Balance during Injury Intravenous fluid administration: When choosing and administering intravenous fluids it is important to consider: • what fluid deficiencies are present. • fluid compartments requiring replacement. • electrolyte disturbances present . • which fluid is most appropriate.

Fluid and Electrolyte Balance during Injury Types of intravenous fluid: Dextrose • After the IV administration of 1000 ml 5% dextrose solution, about 670ml of water will be added to the lFC and about 330 ml of water to the EFC, of which about 70ml will be intravascular. therefore • Dextrose solutions are of little value as resuscitation fluids to expand intravascular volume

Fluid and Electrolyte Balance during Injury Crystalloids • Sodium chloride 0.9%(NS) and Hartmann' s solution (Ringer) are isotonic solutions • Sodium chloride NS 0.9 contains 9g of sodium chloride dissolved in l000ml of water. • (Ringer's lactate) has a more composition, containing lactate, potassium and calcium addition to sodium and chloride ions.

Fluid and Electrolyte Balance during Injury Crystalloids Both normal saline and Ringer solution • have an osmolality similar to extracellular fluid (about 300m0sm/l) • distribute rapidly to ECF compartment after venous administration .

Fluid and Electrolyte Balance during Injury • One liter of isotonic saline contains 154 meq of sodium and an equivalent number of chloride ions.

Fluid and Electrolyte Balance during Injury Balanced solutions, such as Ringer's lactate • closely match the composition of extracellular fluid by providing physiological concentrations of sodium and lactate in place of bicarbonate. • After administration the lactate is metabolized, resulting in bicarbonate generation.

Fluid and Electrolyte Balance during Injury Balanced solutions, such as Ringer's lactate • Decrease the risk of hyperchloraermia, which can occur following large volumes of fluids NS.

Fluid and Electrolyte Balance during Injury Hypertonic saline solutions • Induce a shift of fluid from the IFC to the EFC • Reducing brain water and increasing intra vascular volume and serum sodium concentration. Potential indications • cerebral oedema • raised intracranial pressure • hyponatraemic seizures • 'small volume' resuscitation of hypovolaemic shock.

Fluid and Electrolyte Balance during Injury Dextrose saline solutions • Commercially available 5% dextrose with 0.9% normal saline is a hypertonic solution (twice the osmolarity of plasma) and should be used with caution.

Fluid and Electrolyte Balance during Injury Colloids: • albumin or be synthetically modified (e.g. gelatins, hydroxyethyl starches [HES], dextrans). • When administered, colloid remains largely within the intravascular space until the colloid particles are removed by the reticuloendothelial system.

Fluid and Electrolyte Balance during Injury Colloids: • The intravascular half-life is usually between 6 and 24 hours and such solutions are therefore appropriate for fluid resuscitation. • Electrolyte-containing solution distributes throughout the EFC. • But No Evidence

Fluid and Electrolyte Balance during Injury