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
Fluid and Electrolyte Balance during Injury Water depletion Pure water depletion is common in surgical practice, and is usually combined with sodium loss. The most frequent causes are inadequate intake or excessive gastrointestinal losses.
Fluid and Electrolyte Balance during Injury Water excess common in patients who receive large volumes of intravenous 5% dextrose in the early postoperative period. Such patients have an increased extracellular volume and are commonly hyponatraemic.
Fluid and Electrolyte Balance during Injury Water Excess: Difficult to detect clinically Patients with water excess usually remain well Oedema may not be evident until the extracellular volume has increased by more than 4 litres.
Fluid and Electrolyte Balance during Injury Hypernatraemia: Normal sodium levels are in range 136- 144mmol/l. Hypernatraemia (>145mmol) results from either water or hypotonic fluid loss or sodium gain.
Fluid and Electrolyte Balance during Injury Hypernatraemia: Water loss is commonly caused by reduced water intake vomiting, diarrhea diuresis, burns sweating and insensible losses from the respiratory tract diabetes insipidus. Typically associated with hypovolaemia
Fluid and Electrolyte Balance during Injury Hypernatraemia: Sodium gain is usually caused by excess sodium administration in hypertonic intravenous fluids Typically associated with hypervolaemia.
Fluid and Electrolyte Balance during Injury Hypovolaemic Hypernatraemia is treated with isotonic crystalloid followed by the more gradual administration of water to correct the relative water deficit. We can use 5%dextrose,1/2 NS or 1/4 NS
Fluid and Electrolyte Balance during Injury Cells, particularly brain cells, adapt to a high sodium concentration in extracellular fluid, and once this adaptation has occurred, rapid correction of severe hypernatraemia can result in a rapid rise in intracellular volume, cerebral oedema, seizures and permanent neurological injury.
Fluid and Electrolyte Balance during Injury Hyponatraemia (Na- < 135mmolfl) can occur with high, low or normal extracellular volume. The commonest cause is the administration of hypotonic intravenous fluids (as intravenous 5% dextrose) is administered in the postoperative period (dilutional hyponatraemia).
Fluid and Electrolyte Balance during Injury Hyponatraemia Other causes include diuretic use and (SIADH) Co-morbidities associated with secondary hyperaldosteronism, such as cirrhosis and congestive cardiac failure.
Fluid and Electrolyte Balance during Injury Sodium deficit This can be calculated as follows: 140- measured sodium x 0.2 x weight in kg where 0.2 refers to the 20% extracellular space which represents the compartment in which sodium is the main cation.
Fluid and Electrolyte Balance during Injury Hyponatraemia Treatment depends on correct identification of the cause: If ECF volume is normal or increased, the most likely cause is excessive intravenous water administration and this will correct spontaneously if water intake is reduced.
Fluid and Electrolyte Balance during Injury Hyponatraemia Although less common in surgical patients, SIADH promotes the renal tubular reabsorption of water independently of sodium concentration, resulting in inappropriately concentrated urine (osmolality> 100m0sm / l) in the face of hypotonic plasma (osmolality< 290m0sm/ l).
Fluid and Electrolyte Balance during Injury Hyponatraemia The urine osmolality helps to distinguish inappropriate ADH secretion from excessive water administration. 'Spot‘ measurement of urine sodium will be high.
Fluid and Electrolyte Balance during Injury Hyponatraemia In patients with decreased ECF volume, hyponatracmia usually indicates combined water and sodium deficiency. This is most frequently the result of Diuresis Diarrhea Adrenal insufficiency Treatment by 0.9 sodium chloride
Fluid and Electrolyte Balance during Injury Hyponatraemia severe hyponatraemia (< 120mmol/ l) associated with confusion, seizures and coma.
Fluid and Electrolyte Balance during Injury Hyponatraemia Rapid correction of sodium concentration can precipitate an irreversible demyelinating condition known as central pontine myelinolysis Sodium concentration should not increase by more than 0.5 mmol/h.
Fluid and Electrolyte Balance during Injury Hyponatraemia This can usually be achieved by the cautious administration of isotonic (0.9%) sodium chloride, occasionally combined with the use of a loop diuretic (e.g. furosemide). Hypertonic saline solutions only for sever hyponatremia with CNS manifestation like seizure
Fluid and Electrolyte Balance during Injury Potassium 98% of total body potassium (around 3500mmol) is intracellular serum potassium concentration (normally 3.5- 5 mmol/ l) is a poor indicator of total body potassium.
Fluid and Electrolyte Balance during Injury Potassium no absolute formula to determine K deficit. When the serum K is < 2.5mmol/ l about 100- 200mmol of KCL will be needed in a 70kg adult. Serial monitoring of serum K is necessary to prevent overcorrection
Fluid and Electrolyte Balance during Injury Potassium Once the serum K comes above 3.0 mmol /1, K supplements can be reduced. Acidosis reduces Na+/kATpase activity and results in a net efflux of potassium from cells and hyperkalaemia. Conversely, alkalosis results in an influx of potassium into cells and hypokalaemia.
Fluid and Electrolyte Balance during Injury Hyperkalaemia This is a potentially life-threatening condition. caused by exogenous administration of K release of K from cells (transcellular shift) as a result of tissue damage or changes in the Na / K-ATPase function impaired renal excretion.
Fluid and Electrolyte Balance during Injury Hyperkalaemia Mild hyperkalaemia (K" < 6mmol/l) is often asymptomatic. High K cause progressive slowing of electrical conduction in the heart and the development of significant cardiac arrhythmias. So ECG is mandatory in all suspected hyperkalaemia
Fluid and Electrolyte Balance during Injury Hyperkalaemia ECG Finding Tall 'tented' T-waves in the precordial leads are the earliest flattening (or loss) of the P waves prolonged PR interval widening of the QRS asystole.
Fluid and Electrolyte Balance during Injury Hyperkalaemia Severe hyperkalaemia (K > 7m mmol/l) requires immediate treatment
Treatment of hyperkalaemia
Fluid and Electrolyte Balance during Injury Hypokalaemia common in surgical patients. Dietary intake of k is normally 60-80 mmol / day. Under normal conditions, the majority of k loss (> 85%) is via the kidneys Maintenance of K balance largely depends on normal renal tubular regulation.
Fluid and Electrolyte Balance during Injury Hypokalaemia K excretion is increased by Metabolic alkalosis Diuresis Increased aldosterone release Increased losses from the GI tract.
Fluid and Electrolyte Balance during Injury Hypokalaemia Diagnostic features Muscle weakness Paralytic ileus Flattening of T waves Prominent u waves
Fluid and Electrolyte Balance during Injury Hypokalaemia For every 3 K ions that come out from the intracellular compartment, one H and two Na ions are exchanged causing extracellular alkalosis and intracellular acidosis.
Fluid and Electrolyte Balance during Injury Hypokalaemia Treatment Oral or NG potassium replacement in mild hypokalaemia. Severe (K" < 2.5 mmol/1) or symptomatic hypokalaemia requires IV replacement.
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Calcium Clinically significant abnormalities in endocrine surgery.
Fluid and Electrolyte Balance during Injury Magnesium Hypomagnesaemia is common in restricted oral intake intravenous fluids for several days
Fluid and Electrolyte Balance during Injury Magnesium It is frequently associated with other electrolyte abnormalities, notably hypokalaemia, hypocalcaemia and hypophosphataemia.
Fluid and Electrolyte Balance during Injury Hypomagnesaemia associated with arrhythmias (most notably torsades de pointes (polymorphic ventricular tachycardia) and atrial fibrillation) Manifestations of are nonspecific (muscle weakness, muscle cramps, altered mentation, tremors, hyperreflexia and generalized seizures).
Fluid and Electrolyte Balance during Injury Hypomagnesaemia When hypokalaemia and hypomagnesaemia coexist it may be difficult to correct the former without correcting the latter.
Fluid and Electrolyte Balance during Injury Phosphate Phosphate is a critical component in many biochemical processes such as ATP synthesis, cell signaling and nucleic acid synthesis.
Fluid and Electrolyte Balance during Injury Hypophosphataemia common in surgical patients Severe (< 0.4 mmol/1) causes widespread cell dysfunction, muscle weakness, impaired myocardial contractility, reduced cardiac output altered sensorium.
Fluid and Electrolyte Balance during Injury Hypophosphataemia most commonly occurs in malnourished and/ or alcoholic patients commencing enteral or parenteral nutrition. Sepsis is another situation in which marked hypophosphataemia can be seen
Fluid and Electrolyte Balance during Injury Hypophosphataemia refeeding syndrome Hypophosphataemia accompanied by fluid retention and an increase in ECF volume To avoid it feeding should be established gradually with measurement and supplementation of serum electrolytes (phosphate, magnesium and potassium).
Fluid and Electrolyte Balance during Injury Hypophosphataemia Treatment Phosphate can be supplemented orally or by slow intravenous infusion.
Fluid and Electrolyte Balance during Injury Acid-base balance Acidosis ('acidaemia' if plasma pH< 7.35) Alkalosis ('alkalaemia' if plasma pH> 7.45). Both acidosis and alkalosis may be respiratory or metabolic in origin.
Fluid and Electrolyte Balance during Injury Acid-base balance VBG is good, ABG is more accurate coupled with measurement of blood lactate concentration
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Acid-base balance Acid-base abnormalities are tackled by the body by means of blood buffers respiratory system kidneys.
Fluid and Electrolyte Balance during Injury Acid-base balance When the cause is metabolic, respiratory compensation is the most rapid (minutes) followed by the buffering systems hours) and kidneys (days).
Fluid and Electrolyte Balance during Injury Acid-base balance Bicarbonate buffer is the most important in the blood (65%) followed by the protein buffers (30%).
Fluid and Electrolyte Balance during Injury Acid-base balance Bicarbonate buffer (buffer is an acid-base combination where the acid is only partially dissociated) moves from left to right or vice versa depending on the addition of or loss of acid load with an aim to keep the HCO3/ H2CO3 ratio at 20:1.
Fluid and Electrolyte Balance during Injury Metabolic acidosis increase in plasma hydrogen ions in conjunction with a decrease in bicarbonate concentration. A rise in plasma hydrogen ion concentratlon stimulates chemoreceptors in the medulla resulting in a compensatory respiratory alkalosis an increase in minute volume and a fall in PaCO2
Fluid and Electrolyte Balance during Injury Metabolic acidosis Causes Endogenous acid (e.g. lactic acid or ketone bodies) referred to as 'increased anion gap acidosis' or Increased loss of bicarbonate (e.g. intestinal fistula, hyperchloraemic acidosis) which leads to 'normal anion gap acidosis'.
Fluid and Electrolyte Balance during Injury Metabolic acidosis Anion gap 12-l5mmol/l. Na - (Cl + HCO3)
Fluid and Electrolyte Balance during Injury Metabolic acidosis In surgery or trauma lactic acidosis is the communist cause
Fluid and Electrolyte Balance during Injury Metabolic acidosis Base deficit is a measure of the amount of bicarbonate required to correct acidosis and is calculated as follows: Base deficit= normal bicarbonate- measured bicarbonate x0.2 x weight in kg. where 0.2 refers to the extracellular compartment.
Fluid and Electrolyte Balance during Injury Metabolic acidosis Treatment is directed towards restoring circulating blood volume and tissue perfusion. Blood gas analysis should be repeated every 4-6 hours to assess the requirement for further corrections
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Metabolic alkalosis A decrease in plasma hydrogen ion concentration and an increase in bicarbonate concentration. A rise in PaCO2 occurs as a consequence of the rise in bicarbonate concentration, resulting in a compensatory respiratory acidosis.
Fluid and Electrolyte Balance during Injury Metabolic alkalosis in surgery Mainly due to hypokalaemia and hypochloraemia. The kidney has an enormous capacity to generate bicarbonate ions and this is stimulated by chloride loss.
Fluid and Electrolyte Balance during Injury Metabolic alkalosis Example Metabolic alkalosis seen following significant (chloride-rich) losses from the GI tract when combined with loss of acid from conditions such as gastric outlet obstruction.
Fluid and Electrolyte Balance during Injury Metabolic alkalosis Treatment Adequate fluid replacement Correction of electrolyte disturbances, notably hypokalaemia and hypochloraemia Treatment of the primary cause.
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Respiratory acidosis common postoperative problem Increased PC02 and plasma bicarbonate concentrations. Hypoventilation Examples general anaesthesia excessive opiate administration
Fluid and Electrolyte Balance during Injury Respiratory acidosis Hypoventilation respiratory acidosis require ventilatory support
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Respiratory alkalosis Respiratory alkalosis is caused by excessive excretion of CO2 as a result of hyperventilation. PCO2 and hydrogen ion-concentration decrease. Respiratory alkalosis is rarely chronic and usually does not need specific treatment.
Fluid and Electrolyte Balance during Injury
Fluid and Electrolyte Balance during Injury Mixed patterns of acid-base imbalance Mixed patterns of acid-base disturbance are common, particularly in very sick patients.
Case 1 39 year old male involved in MVC brought to ED by EMT, he is unconscious, hr 120 bp 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 Summary Understand of The Normal Regulation of Fluid Balance Fluid Imbalance In Shock State Early Hemodynamic Optimization Fluid Therapy (Types) & Indication Electrolyte disturbances in trauma and surgery Acid base in surgery patients
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