Seminar on fluids and electrolyte Seminar on fluids and electrolyte imbalanceimbalance

Moderator : Dr. (Mrs.) H.P. SaikiaModerator : Dr. (Mrs.) H.P. Saikia

Dept. of ENTDept. of ENT

AMCH, DibrugarhAMCH, Dibrugarh

Presented by : Dr. Shib Shankar RoyPresented by : Dr. Shib Shankar Roy

11STST yr. PGT, yr. PGT,

Dept. of ENT,Dept. of ENT,

AMCH, DibrugarhAMCH, Dibrugarh

Basic physiology :Basic physiology :

Total body water :Total body water : Total body water content is about 60% of Total body water content is about 60% of

body weight in an young adult male and body weight in an young adult male and about 50% in an young adult female. Since about 50% in an young adult female. Since fat contains less water, an obese person will fat contains less water, an obese person will have proportionately less body water as have proportionately less body water as compared to lean person.compared to lean person.

Distribution of body fluid :Distribution of body fluid : Out of total body water two third (40% of body Out of total body water two third (40% of body

weight) is intracellular fluid & one third (20% of weight) is intracellular fluid & one third (20% of body weight) is extracellular fluid.body weight) is extracellular fluid.

Extracellular fluid is further divided into Extracellular fluid is further divided into interstitial fluid (3/4 of ECF or 15% of total interstitial fluid (3/4 of ECF or 15% of total body weight) and plasma or intravascular body weight) and plasma or intravascular volume (1/4 of ECF, 1/12 of total body water or volume (1/4 of ECF, 1/12 of total body water or 5% of total body weight). 5% of total body weight).

For better understanding, distribution of fluid volume For better understanding, distribution of fluid volume in a 70kg man is summarized below :in a 70kg man is summarized below :

Fluid typeFluid type TotalTotal ICF ICF ECF ECF Interstitial Interstitial Plasma Plasma

% of % of body body

weightweight

60%60% 40%40% 20%20% 15%15% 5%5%

Vol. for Vol. for 70kg 70kg

weightweight

42L42L 28L28L 14L14L 10.5L10.5L 3.5L3.5L

Normal water balance :Normal water balance :

Oral (or I.V.) fluid intake and urine output Oral (or I.V.) fluid intake and urine output are important measurable parameters of are important measurable parameters of body fluid balance. To determine daily fluid body fluid balance. To determine daily fluid requirement of body we need to know requirement of body we need to know insensible fluid input and loss as insensible fluid input and loss as summarized on next page :summarized on next page :

Insensible fluid input = 300 ml water due to oxidation.Insensible fluid input = 300 ml water due to oxidation.

Insensible fluid loss = 500ml through skinInsensible fluid loss = 500ml through skin

= 400ml through lung= 400ml through lung

=100ml through stool=100ml through stool

Fluid loss – fluid input = 1000ml – 300ml = 700mlFluid loss – fluid input = 1000ml – 300ml = 700ml

NORMAL DAILY INSENSIBLE FLUID LOSS = 700mlNORMAL DAILY INSENSIBLE FLUID LOSS = 700ml

Fluid loss = 500ml through moderate sweating(abnormal)Fluid loss = 500ml through moderate sweating(abnormal)

= 1 to 1.5 L through severe sweating/high fever= 1 to 1.5 L through severe sweating/high fever

= 0.5 to 3L through exposed wound surface = 0.5 to 3L through exposed wound surface (burns) and body cavity (laparotomy).(burns) and body cavity (laparotomy).

So higher amt. of water is lost during exercise, abnormal So higher amt. of water is lost during exercise, abnormal perspiration, pyrexia, burns and surgery. This basic perspiration, pyrexia, burns and surgery. This basic information is needed to calculate daily fluid requirements information is needed to calculate daily fluid requirements in patients on I.V. fluids.in patients on I.V. fluids.

In a normal person daily fluid requirement is the sum of In a normal person daily fluid requirement is the sum of urine output and insensible losses. In normal person daily urine output and insensible losses. In normal person daily insensible loss is 700ml. So daily fluid requirement = urine insensible loss is 700ml. So daily fluid requirement = urine output + 700ml. After water distribution, we will see output + 700ml. After water distribution, we will see distribution of electrolytes. Major cation is sodium in ECF distribution of electrolytes. Major cation is sodium in ECF and potassium and magnesium in ICF, while major anion is and potassium and magnesium in ICF, while major anion is chloride in ECF and phosphate, sulphate and proteins in chloride in ECF and phosphate, sulphate and proteins in ICF.ICF.

The electrolyte concentration of body fluids (mEq/L)The electrolyte concentration of body fluids (mEq/L)

Electrolytes (mEq/L)Electrolytes (mEq/L) ECFECF ICFICF

SodiumSodium 142142 1010

PotassiumPotassium 4.34.3 150150

ChlorideChloride 104104 22

BicarbonateBicarbonate 2424 66

CalciumCalcium 55 0.010.01

MagnesiumMagnesium 33 4040

Phosphate & Phosphate & sulphatesulphate

88 150150

Fluids :Fluids :

Fluid intake :Fluid intake : Fluid intake is derived from two sources : exogenous; and Fluid intake is derived from two sources : exogenous; and

endogenous.endogenous. Exogenous water is either drunk or ingested in solid food. Exogenous water is either drunk or ingested in solid food.

The quantities vary within wide limits, but average The quantities vary within wide limits, but average 2-3L/day, of which nearly half is contained in solid food.2-3L/day, of which nearly half is contained in solid food.

Endogenous water is released during the oxidation of Endogenous water is released during the oxidation of ingested food; the amt is normally less than 500ml/day. ingested food; the amt is normally less than 500ml/day. However, during starvation, this amt is supplemented by However, during starvation, this amt is supplemented by water released from the breakdown of tissues. water released from the breakdown of tissues.

Fluid output :Fluid output : Water is lost from the body by 4 routes viz :Water is lost from the body by 4 routes viz : By the lungs By the lungs – About 400ml of water is lost in expired air per – About 400ml of water is lost in expired air per

day. In a dry atmosphere, and when the respiratory rate is day. In a dry atmosphere, and when the respiratory rate is increased, the loss is correspondingly greater(as found in increased, the loss is correspondingly greater(as found in tracheal intubation).tracheal intubation).

By the skin By the skin – When the body becomes overheated, there is – When the body becomes overheated, there is visible perspiration, but throughout life invisible perspiration is visible perspiration, but throughout life invisible perspiration is always occurring. The cutaneous fluid loss varies within wide always occurring. The cutaneous fluid loss varies within wide limits in accordance with atmospheric temperature and limits in accordance with atmospheric temperature and humidity, muscular activity and body temperature. In a humidity, muscular activity and body temperature. In a temperate climate the average loss is between 600ml and temperate climate the average loss is between 600ml and 1000ml/day.1000ml/day.

Faeces Faeces – Between 60 and 150ml of water are lost by this – Between 60 and 150ml of water are lost by this route daily. In diarrhea this amt is greatly multiplied. route daily. In diarrhea this amt is greatly multiplied.

UrineUrine – The output of urine is under the control of multiple – The output of urine is under the control of multiple influences, such as blood volume, hormonal and nervous influences, such as blood volume, hormonal and nervous influences, among which the antidiuretic hormone plays a influences, among which the antidiuretic hormone plays a major role controlling tonicity of the body fluids, a function major role controlling tonicity of the body fluids, a function that it performs by stimulating the reabsorption of water that it performs by stimulating the reabsorption of water from the renal tubules. The normal urinary output is from the renal tubules. The normal urinary output is approximately 1500ml/day, and provided that the kidneys approximately 1500ml/day, and provided that the kidneys are healthy, the specific gravity of the urine bears a direct are healthy, the specific gravity of the urine bears a direct relationship to the volume. A minimum urinary output of relationship to the volume. A minimum urinary output of approximately 400ml/day is required to excrete the end approximately 400ml/day is required to excrete the end products of protein metabolism. products of protein metabolism.

Water imbalance :Water imbalance :

Water depletion : Water depletion : Pure water depletion is usually due to diminished intake. Pure water depletion is usually due to diminished intake.

This may be due to lack of availability, difficulty or inability This may be due to lack of availability, difficulty or inability to swallow because of painful conditions of the mouth and to swallow because of painful conditions of the mouth and pharynx, or obstruction in the oesophagus. Exhaustion and pharynx, or obstruction in the oesophagus. Exhaustion and paresis of the pharyngeal muscles will produce a similar paresis of the pharyngeal muscles will produce a similar picture. Pure water depletion may also follow the increased picture. Pure water depletion may also follow the increased loss from the lungs after tracheostomy. This loss may be loss from the lungs after tracheostomy. This loss may be as much as 500ml in excess of the normal insensible loss. as much as 500ml in excess of the normal insensible loss. After tracheostomy, humidification of the inspired air is an After tracheostomy, humidification of the inspired air is an important preventive measure. important preventive measure.

Clinical features :Clinical features : The main symptoms are weakness and intense thirst. The The main symptoms are weakness and intense thirst. The

urinary output is diminished and its specific gravity urinary output is diminished and its specific gravity increased. The increased serum osmotic pressure causes increased. The increased serum osmotic pressure causes water to leave the cells (intracellular dehydration), and thus water to leave the cells (intracellular dehydration), and thus delays the onset of overt compensated hypovolemia. delays the onset of overt compensated hypovolemia.

Water intoxication :Water intoxication : This can occur when excessive amts of water, low This can occur when excessive amts of water, low

sodium or hypotonic solutions are taken or given sodium or hypotonic solutions are taken or given by any route. The commonest cause on surgical by any route. The commonest cause on surgical wards is the overprescribing of IV 5% dextrose wards is the overprescribing of IV 5% dextrose solutions to post operative patiens.solutions to post operative patiens.

Similarly, water intoxication can occur if the body Similarly, water intoxication can occur if the body retains water in excess to plasma solutes. This retains water in excess to plasma solutes. This can be seen in SIADH secretion which is most can be seen in SIADH secretion which is most commonly associated with lung conditions such as commonly associated with lung conditions such as lobar pneumonia, empyema and Oat cell Ca of lobar pneumonia, empyema and Oat cell Ca of bronchus, as well as head injury. bronchus, as well as head injury.

Clinical features:Clinical features: Drowsiness, weakness, sometimes convulsions and coma. Drowsiness, weakness, sometimes convulsions and coma.

Nausea, vomiting of clear fluid are common. Nausea, vomiting of clear fluid are common. Lab. invstn. may show a falling hematocrit, serum sodium Lab. invstn. may show a falling hematocrit, serum sodium

and electrolyte concentrations.and electrolyte concentrations. Treatment :Treatment : Water is to be restricted. The administration of diuretics or Water is to be restricted. The administration of diuretics or

hypertonic saline should not be undertaken lightly as rapid hypertonic saline should not be undertaken lightly as rapid changes in serum sodium concentration may result in changes in serum sodium concentration may result in neuronal demyelination and a fatal outcome.neuronal demyelination and a fatal outcome.

Electrolyte balance :Electrolyte balance : Sodium balance :Sodium balance : Sodium is principal cation content of ECF. The total body sodium Sodium is principal cation content of ECF. The total body sodium

amounts to approximately 5000mmol, of which 44% is in ECF, 9% amounts to approximately 5000mmol, of which 44% is in ECF, 9% in the ICF and the remaining 47% in bone. in the ICF and the remaining 47% in bone.

Na, with its equivalent anions, accounts for about 90% of the Na, with its equivalent anions, accounts for about 90% of the osmotic pr. of the plasma. The serum Na value is normally b/w 137 osmotic pr. of the plasma. The serum Na value is normally b/w 137 & 147 mmol/L.& 147 mmol/L.

Thus there is a large storehouse ready to compensate abnormal Thus there is a large storehouse ready to compensate abnormal loss from the body.loss from the body.

Daily intake of sodium is 1mmol/kg NaCl or 500ml of isotonic 0.9% Daily intake of sodium is 1mmol/kg NaCl or 500ml of isotonic 0.9% saline soln. An equivalent amount is excreted daily, mainly in the saline soln. An equivalent amount is excreted daily, mainly in the urine and some in the faeces. The loss in perspiration normally is urine and some in the faeces. The loss in perspiration normally is negligible; however people not acclimatized to tropical heat may negligible; however people not acclimatized to tropical heat may have considerable loss of sodium as much as 85mmol/hr. If water have considerable loss of sodium as much as 85mmol/hr. If water alone is given to counter balance the fluid loss, serious sodium alone is given to counter balance the fluid loss, serious sodium depletion can occur from excessive sweating. depletion can occur from excessive sweating.

Factors controlling the balance :Factors controlling the balance :

Control by adrenal corticoids :Control by adrenal corticoids : The output of sodium, governed by the variation in the avidity The output of sodium, governed by the variation in the avidity

with which the renal tubules reabsorb sodium excreted from with which the renal tubules reabsorb sodium excreted from the glomerular filtrate and the amt of Na excreted by the the glomerular filtrate and the amt of Na excreted by the sweat glands, is under the control of adrenal corticoids, the sweat glands, is under the control of adrenal corticoids, the most powerful conservator of Na being aldosterone.most powerful conservator of Na being aldosterone.

The Na excretion shut down in trauma :The Na excretion shut down in trauma : Following trauma/surgery there is a variable period of Following trauma/surgery there is a variable period of

reduced excretion of Na. For this reason it may be reduced excretion of Na. For this reason it may be inadvisable to administer large quantities of isotonic (0.9%) inadvisable to administer large quantities of isotonic (0.9%) saline solution after an operation. This period of Na excretion saline solution after an operation. This period of Na excretion shut down can last for upto 48hrs & is due to increased shut down can last for upto 48hrs & is due to increased adrenocortical activity. adrenocortical activity.

Sodium depletion (hyponatreamia) :Sodium depletion (hyponatreamia) : Causes :Causes : Small bowelSmall bowel obstruction, vomiting, aspiration.obstruction, vomiting, aspiration. Severe diarrhoea due to dysentery, cholera, UC Severe diarrhoea due to dysentery, cholera, UC

(alongwith acidosis).(alongwith acidosis). C/f : C/f : It is mainly due to extracellular dehydration.It is mainly due to extracellular dehydration. Sunken eyes, drawn face, coated & dry tongue in Sunken eyes, drawn face, coated & dry tongue in

advanced cases it is brown in colour, thirst is absent.advanced cases it is brown in colour, thirst is absent. Dry & wrinkled skin ----- pat. looks aged.Dry & wrinkled skin ----- pat. looks aged. Sub cut. tissue feels lax.Sub cut. tissue feels lax. Art blood pr is likely to be below normal.Art blood pr is likely to be below normal. Scanty dark colour urine of high specific gravity.Scanty dark colour urine of high specific gravity.

T/t :T/t : It must be individualized considering the etiology, the rate It must be individualized considering the etiology, the rate

of development (acute vs chronic), severity & clinical signs & of development (acute vs chronic), severity & clinical signs & symptoms.symptoms.

Dictum :Dictum : ↓Na, which develops quickly should be treated ↓Na, which develops quickly should be treated rapidly, whereas, which develops slowly should be corrected rapidly, whereas, which develops slowly should be corrected slowly.slowly.

Goal of therapy :Goal of therapy : To raise the plasma Na conc. at a safe rate.To raise the plasma Na conc. at a safe rate. To replace Na deficit or K deficit or both.To replace Na deficit or K deficit or both. To correct underlying etiology.To correct underlying etiology. In general ↓Na is corrected acutely by giving Na to pats. who In general ↓Na is corrected acutely by giving Na to pats. who

are vol. depleted and by restricting water intake in pats. who are vol. depleted and by restricting water intake in pats. who are normovolemic & oedematous. are normovolemic & oedematous.

Specific t/t : Specific t/t : Removal of the drugs responsible for it, like diuretics, Removal of the drugs responsible for it, like diuretics,

clorpropamide, i.v. cyclophosphamide.clorpropamide, i.v. cyclophosphamide. Management of physical stress, P.O. pain.Management of physical stress, P.O. pain. Specific t/t for adrenal insufficiency, hypothyroidism, Specific t/t for adrenal insufficiency, hypothyroidism,

uncontrolled diabetes & ketoacidosis.uncontrolled diabetes & ketoacidosis.

Hypernatraemia :Hypernatraemia : Causes :Causes : Excess water loss : heat exposure, severe burns, severe exercise, pat. on Excess water loss : heat exposure, severe burns, severe exercise, pat. on

mechanical ventilator.mechanical ventilator. Water deficit due to impaired thirst : comatose pat.Water deficit due to impaired thirst : comatose pat. Na retention : excessive I/V hypertonic NaCl.Na retention : excessive I/V hypertonic NaCl.

C/f :C/f : slight puffiness of the face is the only early sign.slight puffiness of the face is the only early sign. Pitting oedema should be sought, esp. in the sacral region.Pitting oedema should be sought, esp. in the sacral region. But for pitting oedema to be present at least 4.5L of excess fluid must But for pitting oedema to be present at least 4.5L of excess fluid must

have accumulated in tissue spaces. have accumulated in tissue spaces. C/f is mainly neurological, this is the only state in which dry sticky mucous C/f is mainly neurological, this is the only state in which dry sticky mucous

membrane is characteristic & body temp is generally elevated. Major membrane is characteristic & body temp is generally elevated. Major neurological symptoms include nausea, ms weakness, altered mental status, neurological symptoms include nausea, ms weakness, altered mental status, neuromuscular irritability, focal neurological deficit and occasionally coma or neuromuscular irritability, focal neurological deficit and occasionally coma or seizures. seizures.

T/t :T/t : Therapeutic goals are :Therapeutic goals are : To stop ongoing fluid loss by treating the underlying causes.To stop ongoing fluid loss by treating the underlying causes. To correct water deficit.To correct water deficit. Two important factors to decide t/t plan are :Two important factors to decide t/t plan are :

– ECF vol. statusECF vol. status– rate of development of ↑Na.rate of development of ↑Na.

The imp t/t aspects are :The imp t/t aspects are : To diagnose and treat specific etiology.To diagnose and treat specific etiology. Rate of correction : in acute ↑Na the water deficit can be replaced Rate of correction : in acute ↑Na the water deficit can be replaced

relatively rapidly, without increasing the risk of cerebral oedema. In acute relatively rapidly, without increasing the risk of cerebral oedema. In acute ↑Na targeted rate of correction of ↑Na is 1mEq/L/hr. Rapid correction of ↑Na targeted rate of correction of ↑Na is 1mEq/L/hr. Rapid correction of chr. ↑Na is dangerous. It may lead to cerebral oedema.chr. ↑Na is dangerous. It may lead to cerebral oedema.

Goal of treatment : the goal is to reduce serum Na conc to 145mEq/L.Goal of treatment : the goal is to reduce serum Na conc to 145mEq/L. T/t of ↑Na is water, safest route of administration of water is by mouth or T/t of ↑Na is water, safest route of administration of water is by mouth or

via a nasogastric tube. via a nasogastric tube.

Potassium balance :Potassium balance : K is almost entirely intracellular, only 2% is present in ECF. K is almost entirely intracellular, only 2% is present in ECF.

¾ th of the total body K (approx 3500mmol) is found in ¾ th of the total body K (approx 3500mmol) is found in skeletal ms. When the body needs endogenous protein as skeletal ms. When the body needs endogenous protein as a source of energy, K as well as nitrogen is mobilized.a source of energy, K as well as nitrogen is mobilized.

The normal range of K is 3.5 – 5mmol/L. K deficiency is The normal range of K is 3.5 – 5mmol/L. K deficiency is present, if the serum K value is less than 3.5mmol/L.present, if the serum K value is less than 3.5mmol/L.

Each day a normal adult ingests approx 1mmol/kg of K in Each day a normal adult ingests approx 1mmol/kg of K in food; Fruit, milk & honey are rich in this cation. food; Fruit, milk & honey are rich in this cation.

↓↓K :K : Following trauma, including operation trauma, Following trauma, including operation trauma,

there is a spell, varying directly with the degree there is a spell, varying directly with the degree tissue damage, of increased excretion by the tissue damage, of increased excretion by the kidneys. So great are the body’s reserves of K kidneys. So great are the body’s reserves of K that, unless the pat was severely depleted at the that, unless the pat was severely depleted at the time of the operation, ↓K may not reveal itself for time of the operation, ↓K may not reveal itself for 48hrs. However, K is such a key IC cation that 48hrs. However, K is such a key IC cation that carefully monitored replacement should start early carefully monitored replacement should start early in the P.O period in all pats, with the exception of in the P.O period in all pats, with the exception of those that have evidence of renal dysfunction. those that have evidence of renal dysfunction.

C/f :C/f : Listlessness and slurred speech, muscular Listlessness and slurred speech, muscular

hypotonia, depressed reflexes and abdominal hypotonia, depressed reflexes and abdominal distension as a result of paralytic ileus.distension as a result of paralytic ileus.

Weakness of the respiratory ms may Weakness of the respiratory ms may result in rapid, shallow, gasping respirations; these result in rapid, shallow, gasping respirations; these are conducive to PO pulmonary complications. are conducive to PO pulmonary complications. The diagnosis is supported by ECG, which may The diagnosis is supported by ECG, which may show a prolonged QT interval, depression of the show a prolonged QT interval, depression of the ST segment and flattening or inversion of the T- ST segment and flattening or inversion of the T- wave. wave.

T/t :T/t : Oral K : It can be given in the form of milk, meat Oral K : It can be given in the form of milk, meat

extracts, fruit juices and honey. Potassium extracts, fruit juices and honey. Potassium chloride 2g can be given per mouth 6hrly.chloride 2g can be given per mouth 6hrly.

I/V K : Rapid intravenous supplementation carries I/V K : Rapid intravenous supplementation carries the risk of dysrrhythmias and cardiac arrest if the the risk of dysrrhythmias and cardiac arrest if the serum conc. rises to a dangerous level.serum conc. rises to a dangerous level.

When there’s no associated alkalosis, the K deficit When there’s no associated alkalosis, the K deficit can be restored by adding 40mmol KCl to each can be restored by adding 40mmol KCl to each litre of 5% D, 0.9% saline soln., which is given 6-8 litre of 5% D, 0.9% saline soln., which is given 6-8 hrly.hrly.

↑↑K :K : Causes :Causes : ↑ ↑ intake :intake : - I/V fluid containing K- I/V fluid containing K - high K containing foods.- high K containing foods. - K containing drugs.- K containing drugs. Tissue breakdown :Tissue breakdown : Bleeding into the soft tissue, GI tract or body cavities.Bleeding into the soft tissue, GI tract or body cavities. Hemolysis, rhabdomyolysis.Hemolysis, rhabdomyolysis. Shift of K out of the cell :Shift of K out of the cell : tissue damage, severe exercise,tissue damage, severe exercise, uncontrolled DMuncontrolled DM Impaired excretion :Impaired excretion : ARF or CRF.ARF or CRF.

C/f :C/f : ↑ ↑K is often asymptomatic until plasma K conc is above 6.5 – 7 K is often asymptomatic until plasma K conc is above 6.5 – 7

mEq/L and may lead to fatal cardiac arrhythmia hence it is called mEq/L and may lead to fatal cardiac arrhythmia hence it is called silent killer.silent killer.

Vague muscular weakness, hyporeflexia, gradual paralysis Vague muscular weakness, hyporeflexia, gradual paralysis affecting initially legs, then trunk and arms, and at last face & affecting initially legs, then trunk and arms, and at last face & respiratory muscles & later on ultimately cardiac arrest and death respiratory muscles & later on ultimately cardiac arrest and death occurs.occurs.

T/t :T/t : Principle for the treatment of ↑K :Principle for the treatment of ↑K : Antagonism of membrane effects : Inj. Calcium gluconate.Antagonism of membrane effects : Inj. Calcium gluconate. K movt. into the cells : insulin & glucose, βK movt. into the cells : insulin & glucose, β22 agonist : salbutamol. agonist : salbutamol. Removal of K from the body : cation exchange resin, hemodialysis Removal of K from the body : cation exchange resin, hemodialysis

or peritoneal dialysis, loop or thiazide diuretics.or peritoneal dialysis, loop or thiazide diuretics.

Calcium :Calcium : Ca is an EC cation with a plasma conc. of 2.2 – 2.5mmol/L. It Ca is an EC cation with a plasma conc. of 2.2 – 2.5mmol/L. It

exists in 3 forms : bound to protein, free non-ionised, free ionized exists in 3 forms : bound to protein, free non-ionised, free ionized – the last form being the component necessary for blood – the last form being the component necessary for blood coagulation & affecting neuromuscular excitability. The ionized coagulation & affecting neuromuscular excitability. The ionized proportion falls with increasing pH; thus in respiratory alkalosis proportion falls with increasing pH; thus in respiratory alkalosis due to hyperventilation there may be tetany – with an apparently due to hyperventilation there may be tetany – with an apparently normal total serum Ca level.normal total serum Ca level.

The serum level of Ca is under the control of : factors like – vit. D The serum level of Ca is under the control of : factors like – vit. D and phytic acid, parathormone & calcitonin.and phytic acid, parathormone & calcitonin.

The management of abnormal Ca blood levels depends, where The management of abnormal Ca blood levels depends, where possible, on removal of the cause, for e.g. removal of a possible, on removal of the cause, for e.g. removal of a parathyroid tumour or in the coagulation disorder due to massive parathyroid tumour or in the coagulation disorder due to massive transfusion of blood containing acid citrate dextrose, 10ml of transfusion of blood containing acid citrate dextrose, 10ml of 10% of Ca – gluconate may be injected slowly intravenously.10% of Ca – gluconate may be injected slowly intravenously.

Magnesium :Magnesium : Mg is an IC cation which shares some of the properties of K Mg is an IC cation which shares some of the properties of K

& some of Ca.& some of Ca. The normal Mg conc. is 0.7 – 0.9mmol/L. The avg. daily The normal Mg conc. is 0.7 – 0.9mmol/L. The avg. daily

intake is approx. 10mmol.intake is approx. 10mmol. Mg deficiency occur due very prolonged administration of I/V Mg deficiency occur due very prolonged administration of I/V

fluids without Mg supplements.fluids without Mg supplements. The clinical picture of Mg def. is marked by CNS irritability, The clinical picture of Mg def. is marked by CNS irritability,

ECG changes, lowered BP and lowered protein synthesis. ECG changes, lowered BP and lowered protein synthesis. P.O. cardiac arrythmias are commonly associated with both P.O. cardiac arrythmias are commonly associated with both ↓K & ↓Mg.↓K & ↓Mg.

T/t :T/t : For the t/t of mild ↓Mg 20mmol as MgSO4 can be added to For the t/t of mild ↓Mg 20mmol as MgSO4 can be added to

5% D or NS over 24 hr period.5% D or NS over 24 hr period.

Acid – base balance :Acid – base balance : In health, the blood H+ ion conc. lies within range pH 7.36 In health, the blood H+ ion conc. lies within range pH 7.36

– 7.44. In acidosis, there’s accumulation of acid or a loss of – 7.44. In acidosis, there’s accumulation of acid or a loss of a base causing a fall in pH. The pH of the blood is a base causing a fall in pH. The pH of the blood is regulated & controlled by various buffering systems, of regulated & controlled by various buffering systems, of which the most important is the HCOwhich the most important is the HCO33 -- : H : H22COCO33 ratio. It is ratio. It is also regulated by the removal of CO2 by the lungs and by also regulated by the removal of CO2 by the lungs and by the excretion of both acids & bases by the kidneys.the excretion of both acids & bases by the kidneys.

The ratio of HCOThe ratio of HCO33 -- : H : H22COCO33 is normally 20:1. A decrease in is normally 20:1. A decrease in the ratio leads to increased acidity and vice versa.the ratio leads to increased acidity and vice versa.

The bicarbonate level can be altered by metabolic factors, The bicarbonate level can be altered by metabolic factors, while the carbonic acid level is subject to alteration by while the carbonic acid level is subject to alteration by respiratory factors. respiratory factors.

Measurement of acid – base disturbances :Measurement of acid – base disturbances : These measurements are normally made on arterial or These measurements are normally made on arterial or

arterial capillary blood. pCOarterial capillary blood. pCO22 is a measurement of the is a measurement of the tension or partial pressure of carbon dioxide in the blood. tension or partial pressure of carbon dioxide in the blood. The normal arterial pCOThe normal arterial pCO22 is 4.1 – 5.6 kPa (31 – 42 mmHg). is 4.1 – 5.6 kPa (31 – 42 mmHg). pOpO22 is a measurement of the tension or partial pressure of is a measurement of the tension or partial pressure of oxygen in blood. The normal value is 10.5 – 14.5 kPa (80 – oxygen in blood. The normal value is 10.5 – 14.5 kPa (80 – 110 mmHg).110 mmHg).

Standard bicarbonate is the conc. of the serum bicarbonate Standard bicarbonate is the conc. of the serum bicarbonate after fully oygeneted blood has been equilibrated with COafter fully oygeneted blood has been equilibrated with CO22 at 40mmHg at 38 °C. This eliminates respiratory causes & at 40mmHg at 38 °C. This eliminates respiratory causes & respiratory compensation for altered bicarbonate levels. respiratory compensation for altered bicarbonate levels. Normal levels are 22 – 25 mmol/L. Normal levels are 22 – 25 mmol/L.

Alkalosis :Alkalosis : Metabolic alkalosis :Metabolic alkalosis : Metabolic alkalosis, a condn. of base excess or a deficit of any acid Metabolic alkalosis, a condn. of base excess or a deficit of any acid

other than Hother than H22COCO33, can be caused by:, can be caused by: Excessive ingestion of absorbable alkali.Excessive ingestion of absorbable alkali. Loss of acid from stomach by repeated vomiting or aspiration.Loss of acid from stomach by repeated vomiting or aspiration. Cortisone excessCortisone excess Compensation is effected by : retention of COCompensation is effected by : retention of CO22 by lungs; and excretion by lungs; and excretion

of bicarbonate base by kidneys.of bicarbonate base by kidneys. C/f :C/f : Most striking feature is Cheyne – Stokes respiration with period of Most striking feature is Cheyne – Stokes respiration with period of

apnoea lasting from 5 to 30s.apnoea lasting from 5 to 30s. Tetany sometimes occur.Tetany sometimes occur. Severe alkalosis may result in renal epithelial damage and consequent Severe alkalosis may result in renal epithelial damage and consequent

renal insufficiency.renal insufficiency.

T/t :T/t : Metabolic alkalosis without hypokalemia Metabolic alkalosis without hypokalemia

seldom requires direct treatment. The cause seldom requires direct treatment. The cause of the alkalosis should be removed where of the alkalosis should be removed where possible and a high urinary output is possible and a high urinary output is encouraged. encouraged.

Hypokalemic alkalosis :Hypokalemic alkalosis : Hypokalemic alkalosis is seen in patients who have lost K and Hypokalemic alkalosis is seen in patients who have lost K and

acid owing to repeated vomiting (from P. stenosis). The low acid owing to repeated vomiting (from P. stenosis). The low serum K causes K to leave the cell and be replaced by Naserum K causes K to leave the cell and be replaced by Na++ & & HH++ ions. The shift of H ions. The shift of H++ ion into the cell causes IC acidosis ion into the cell causes IC acidosis and increases the cellular acidosis of the kidney cells. and increases the cellular acidosis of the kidney cells.

T/t :T/t : When hypokalemia is sufficient to cause a metabolic When hypokalemia is sufficient to cause a metabolic

alkalosis, the losses can be massive (>1000 mmol). alkalosis, the losses can be massive (>1000 mmol). Replacement is a serious undertaking. It can be achieved Replacement is a serious undertaking. It can be achieved gradually and relatively safely by supplementing I/V fluids with gradually and relatively safely by supplementing I/V fluids with 40mmol/L of KCl if the urine output is adequate. More rapid 40mmol/L of KCl if the urine output is adequate. More rapid replacement will require intensive monitoring & supervision replacement will require intensive monitoring & supervision with continuous ECG monitoring in a high dependency or with continuous ECG monitoring in a high dependency or ICU. ICU.

Respiratory alkalosis :Respiratory alkalosis : Causes :Causes : excessive pulmonary ventilation in excessive pulmonary ventilation in

anaesthesised pat. which is accompanied anaesthesised pat. which is accompanied by pallor and fall in BP, hyperventilation by pallor and fall in BP, hyperventilation occasioned by high altitudes, hyperpyrexia, occasioned by high altitudes, hyperpyrexia, a lesion of the hypothalamus & hysteria.a lesion of the hypothalamus & hysteria.

T/t :T/t : Respiratory suppression due to alkalosis is Respiratory suppression due to alkalosis is

rectified by insufflation of COrectified by insufflation of CO22..

AcidosisAcidosis

Metabolic acidosis :Metabolic acidosis : Metabolic acidosis, a condition where there is a Metabolic acidosis, a condition where there is a

deficit of base or an excess of any acid other than deficit of base or an excess of any acid other than HH22COCO33, occurs as a result of :, occurs as a result of :

Increase in fixed acids due to formation of ketone Increase in fixed acids due to formation of ketone bodies as in DM or starvation, the retention of bodies as in DM or starvation, the retention of metabolites in renal insufficiency.metabolites in renal insufficiency.

Loss of bases such as occurs in sustained Loss of bases such as occurs in sustained diarrhea, UC, gastrocolic fistula, or prolonged diarrhea, UC, gastrocolic fistula, or prolonged intestinal aspiration. intestinal aspiration.

C/f :C/f : Rapid deep noisy breathing.Rapid deep noisy breathing. The hyperpnoea is due to over stimulation of the The hyperpnoea is due to over stimulation of the

respiratory centre by the reduction in pH of the blood, and respiratory centre by the reduction in pH of the blood, and the physiological purpose of overbreathing is to eliminate the physiological purpose of overbreathing is to eliminate as much as possible of the acid substance.as much as possible of the acid substance.

T/t :T/t : The commonest cause of an acute preoperative metabolic The commonest cause of an acute preoperative metabolic

acidosis is tissue hypoxia and the correct t/t is restoration acidosis is tissue hypoxia and the correct t/t is restoration of adequate tissue perfusion.of adequate tissue perfusion.

The acute acidosis seen in prolonged cardiac arrest may The acute acidosis seen in prolonged cardiac arrest may require the infusion of 50mmol of 8.4% NaHCOrequire the infusion of 50mmol of 8.4% NaHCO33 soln. soln.

Respiratory acidosis :Respiratory acidosis : Respiratory acidosis, a condition where the pCO2 is above the Respiratory acidosis, a condition where the pCO2 is above the

normal range, is caused by impaired alveolar ventilation.normal range, is caused by impaired alveolar ventilation. Most commonly occurs when there’s inadequate ventilation of the Most commonly occurs when there’s inadequate ventilation of the

anaesthesised pat., or when the effects of MRs have not worn off anaesthesised pat., or when the effects of MRs have not worn off or been fully reversed at the end of the anaesthetic. There’s also a or been fully reversed at the end of the anaesthetic. There’s also a risk of respiratory acidosis when the pat. undergoing surgery risk of respiratory acidosis when the pat. undergoing surgery already has pre – existing pulmonary ds.already has pre – existing pulmonary ds.

The anion gapThe anion gap This is a calculated estimation of the undetermined or unmeasured This is a calculated estimation of the undetermined or unmeasured

anions in blood.anions in blood. Anion gap = (Na + K) – (HCOAnion gap = (Na + K) – (HCO33 + Cl) + Cl) The normal anion gap is 10 to 16mmol/L.The normal anion gap is 10 to 16mmol/L. The increased anion gap is seen in metabolic acidosis due to The increased anion gap is seen in metabolic acidosis due to

ketoacidosis, lactic acidosis, poisoning and renal failure. ketoacidosis, lactic acidosis, poisoning and renal failure.

Fluid therapy in surgical patients :Fluid therapy in surgical patients :

Fluid and electrolyte management is an imp. aspect for the Fluid and electrolyte management is an imp. aspect for the care of surgical patients.care of surgical patients.

Proper fluid and electrolyte state is helpful in reducing Proper fluid and electrolyte state is helpful in reducing morbidity and mortality in certain surgical patients.morbidity and mortality in certain surgical patients.

Q. Why fluid therapy in surgical patients needs special Q. Why fluid therapy in surgical patients needs special consideration?consideration?

A. In surgical patients, multiple factors modify the normal A. In surgical patients, multiple factors modify the normal physiology of fluid and electrolyte balance of body and, physiology of fluid and electrolyte balance of body and, therefore, need special consideration. Important factors to therefore, need special consideration. Important factors to be considered are :be considered are :

Acute stress : physical and mental stress which occurs Acute stress : physical and mental stress which occurs before, during and after surgery leads to sympathetic before, during and after surgery leads to sympathetic stimuli, which leads to tachycardia, vasoconstriction, and stimuli, which leads to tachycardia, vasoconstriction, and stress.stress.

In surgical patients secretion of ACTH is increased. In surgical patients secretion of ACTH is increased. Increased ACTH stimulates adrenal glands to secrete Increased ACTH stimulates adrenal glands to secrete hydrocortisone to fight with acute stress and aldosterone hydrocortisone to fight with acute stress and aldosterone which leads to Na retention and urinary loss of K.which leads to Na retention and urinary loss of K.

During major surgery hypovolemia also leads to increased During major surgery hypovolemia also leads to increased aldosterone secretion. This increased secretion for the first aldosterone secretion. This increased secretion for the first 2 – 3 P.O. days leads to decreased Na requirements. This 2 – 3 P.O. days leads to decreased Na requirements. This should be kept in mind.should be kept in mind.

P.O. pain and stress leads to increased ADH secretion from P.O. pain and stress leads to increased ADH secretion from posterior pituitary gland in first 2 – 3 P.O. days. Ultimately posterior pituitary gland in first 2 – 3 P.O. days. Ultimately leads to decreased urine output. Therefore, it is imp. to leads to decreased urine output. Therefore, it is imp. to remember that maintenance fluid required on the 1remember that maintenance fluid required on the 1stst P.O. day P.O. day is lesser.is lesser.

Fluid deficit, which occurs due to preoperative oral fluid Fluid deficit, which occurs due to preoperative oral fluid restriction (NPO), needs consideration and replacement pre restriction (NPO), needs consideration and replacement pre – or intra – operatively.– or intra – operatively.

Abnormal blood as well as fluid loss which occurs before, Abnormal blood as well as fluid loss which occurs before, during and after various surgery needs proper attention and during and after various surgery needs proper attention and careful calculation to decide type, volume and rate of fluid to careful calculation to decide type, volume and rate of fluid to be infused.be infused.

Pat. who is hypovolemic prior to surgery is very likely to become Pat. who is hypovolemic prior to surgery is very likely to become hypotensive during surgery and anaesthesia. Hence hypovolemia hypotensive during surgery and anaesthesia. Hence hypovolemia should preferably be corrected prior to surgery.should preferably be corrected prior to surgery.

Surgical stress or direct damage can affect kidney, brain, lung, skin Surgical stress or direct damage can affect kidney, brain, lung, skin or GI tract. These organs are very useful in maintaining normal or GI tract. These organs are very useful in maintaining normal fluid, electrolytes and acid base balance. So fluid therapy in such fluid, electrolytes and acid base balance. So fluid therapy in such surgical pats. needs special consideration.surgical pats. needs special consideration.

Fluid therapy in surgical pats. can be discussed under 3 headings :Fluid therapy in surgical pats. can be discussed under 3 headings : Pre operativePre operative Intra operativeIntra operative Post operativePost operative

Preoperative fluid therapy :Preoperative fluid therapy :

   Preoperative evaluation and correction of existing fluid and Preoperative evaluation and correction of existing fluid and

electrolytes disorder is very imp. for better outcome in electrolytes disorder is very imp. for better outcome in surgical pats.surgical pats.

It can be discussed under 3 headings :It can be discussed under 3 headings : Correction of hypovolemiaCorrection of hypovolemia Correction of anaemiaCorrection of anaemia Correction of other disorders.Correction of other disorders.

Correction of hypovolemia :Correction of hypovolemia :

   Q. Why to correct hypovolemia preoperatively ?Q. Why to correct hypovolemia preoperatively ? A. Any degree of hypovolemia jeopardizes OA. Any degree of hypovolemia jeopardizes O22 transport and transport and

increases the risk of tissue hypoxia and the development of organ increases the risk of tissue hypoxia and the development of organ failure.failure.

   Causes :Causes :

   Vomiting, NG suction, blood loss, third space loss, fever, Vomiting, NG suction, blood loss, third space loss, fever,

hyperventilation, diuretic therapy, diarrhoea or preoperative bowel hyperventilation, diuretic therapy, diarrhoea or preoperative bowel preparation.preparation.

Q. How to decide the vol. of fluid deficit pre operatively ?Q. How to decide the vol. of fluid deficit pre operatively ? A. It is impossible to decide the fluid deficit exactly, but roughly it A. It is impossible to decide the fluid deficit exactly, but roughly it

can be can be Mild dehydration = 4% body wt. fluid deficit.Mild dehydration = 4% body wt. fluid deficit. Moderate = 6 – 8% body wt. fluid deficit.Moderate = 6 – 8% body wt. fluid deficit. Severe = 10% body wt. fluid deficit.Severe = 10% body wt. fluid deficit.

   The fluid of choice :The fluid of choice : Depending on nature of loss, hemodynamic status and conc. Depending on nature of loss, hemodynamic status and conc.

abnormality.abnormality. It can be 0.9% saline, Ringer’s lactate, colloids and whole blood.It can be 0.9% saline, Ringer’s lactate, colloids and whole blood.

Q. How to monitor fluid therapy ?Q. How to monitor fluid therapy ? A. Improvement in tachycardia and BP, absence of orthostatic A. Improvement in tachycardia and BP, absence of orthostatic

hypotension and achieving urine output > 30 – 50 ml/hr suggest hypotension and achieving urine output > 30 – 50 ml/hr suggest correction of fluid deficit.correction of fluid deficit.

Correction of anaemia :Correction of anaemia :

Q. Why to correct anaemia in surgical pats. ?Q. Why to correct anaemia in surgical pats. ?

A. Correction is imp. :A. Correction is imp. : To establish haemodynamic stability in surgical pat. with blood loss.To establish haemodynamic stability in surgical pat. with blood loss. For proper tissue oxygenation in intra & post operative period.For proper tissue oxygenation in intra & post operative period. To cope up with possible operative blood loss.To cope up with possible operative blood loss. For early recovery and quick healing.For early recovery and quick healing.

Q. When to correct anaemia ?Q. When to correct anaemia ? A. In elective surgery correction of anaemia by blood A. In elective surgery correction of anaemia by blood

transfusion should be done 48 to 72 hrs prior to surgery.transfusion should be done 48 to 72 hrs prior to surgery.

   Q. How to correct anaemia ?Q. How to correct anaemia ? A. Packed cell is always preferred to correct anaemia, as it A. Packed cell is always preferred to correct anaemia, as it

avoids vol. overload. If whole blood needs to be given, it is avoids vol. overload. If whole blood needs to be given, it is safer to give slowly and along with diuretics.safer to give slowly and along with diuretics.

Intraoperative fluid therapy :Intraoperative fluid therapy :

Proper fluid therapy intraoperatively will avoid hypovolemia and Proper fluid therapy intraoperatively will avoid hypovolemia and hypotension. It also maintains proper tissue perfusion and oxygenation.hypotension. It also maintains proper tissue perfusion and oxygenation.

Important causes where we need intraoperative fluid therapy are loss Important causes where we need intraoperative fluid therapy are loss of blood, fluid depletion, third space losses, evaporative losses from of blood, fluid depletion, third space losses, evaporative losses from viscera or wound itself, hypoxia, vasodilatory effect of anaesthetic viscera or wound itself, hypoxia, vasodilatory effect of anaesthetic agents.agents.

Q. Which fluid to give crystalloid or colloid ?Q. Which fluid to give crystalloid or colloid ? A. It’s a matter of dispute.A. It’s a matter of dispute. For rapid restoration of haemodynamic function a colloid does the job For rapid restoration of haemodynamic function a colloid does the job

more effectively than a crystalloid.more effectively than a crystalloid.

Crystalloid :Crystalloid :

   Advantage Advantage :: Most commonly used agent because it is least expensive, readily Most commonly used agent because it is least expensive, readily

available and reaction free.available and reaction free. Disadvantage :Disadvantage : Since it passes readily through semipermeable membrane, it cannot Since it passes readily through semipermeable membrane, it cannot

remain confined to the intravascular compartment so it has short remain confined to the intravascular compartment so it has short lived heamodynamic improvement effect. Larger vol. of crystalloid is lived heamodynamic improvement effect. Larger vol. of crystalloid is needed for correction of hypotension, which can leads to excess salt needed for correction of hypotension, which can leads to excess salt and water retention leading to peripheral and pulmonary oedema. If and water retention leading to peripheral and pulmonary oedema. If the goal is to replenish the interstitial dehydration, then crystalloid will the goal is to replenish the interstitial dehydration, then crystalloid will be t/t of choice.be t/t of choice.

Q. Which I/V fluid should be given intra operatively?Q. Which I/V fluid should be given intra operatively? A. Ringer’s lactate is most widely used fluid, but the A. Ringer’s lactate is most widely used fluid, but the

selection needs to be individualized depending upon age, selection needs to be individualized depending upon age, vital data, basic etiology and type of surgery required, vital data, basic etiology and type of surgery required, associated illness and current fluid and electrolyte status.associated illness and current fluid and electrolyte status.

Basic guidelines for selection are :Basic guidelines for selection are : Ringer’s lactate is used to replace the intraoperative Ringer’s lactate is used to replace the intraoperative

fluid losses. Since it is the most physiological fluid fluid losses. Since it is the most physiological fluid having composition similar to body fluid.having composition similar to body fluid.

Isotonic saline is used where Ringer’s lactate is Isotonic saline is used where Ringer’s lactate is contraindicated or when large vol. of fluid needs to contraindicated or when large vol. of fluid needs to be replaced rapidly i.e. hypovolemic shock.be replaced rapidly i.e. hypovolemic shock.

5D is used as initial fluid replacement, which 5D is used as initial fluid replacement, which replaces insensible fluid loss and maintenance fluid replaces insensible fluid loss and maintenance fluid deficit during starvation.deficit during starvation.

Colloids :Colloids :

Intraoperative colloids are used selectively when rapid restoration of plasma Intraoperative colloids are used selectively when rapid restoration of plasma vol. is needed to correct severe acute hypotension.vol. is needed to correct severe acute hypotension.

Advantages :Advantages : It never cross semipermeable membrane and remain in the intravascular It never cross semipermeable membrane and remain in the intravascular

compartment. So more effective than crystalloid in treating hypotension.compartment. So more effective than crystalloid in treating hypotension. Increase in the plasma vol. is for prolonged period as compared to crystalloid.Increase in the plasma vol. is for prolonged period as compared to crystalloid. Smaller vol. of colloids improve the haemodynamic status. Avoid excessive Smaller vol. of colloids improve the haemodynamic status. Avoid excessive

salt and water administration, thereby reducing chances of peripheral oedema.salt and water administration, thereby reducing chances of peripheral oedema. Better haemodynamic stability so higher systemic oxygen delivery indirectly.Better haemodynamic stability so higher systemic oxygen delivery indirectly.

Disadvantages :Disadvantages : Much more expensive than crystalloid.Much more expensive than crystalloid. Rapid and larger infusion can cause pulmonary oedema.Rapid and larger infusion can cause pulmonary oedema. Higher risk for hypersensitivity reaction and bleeding (esp. with dextran).Higher risk for hypersensitivity reaction and bleeding (esp. with dextran). Glomerular filtration is reduced, so increase accumulation of nitrogenous end Glomerular filtration is reduced, so increase accumulation of nitrogenous end

product.product.

   Indications :Indications : These are used to treat sudden hypotension due major blood loss till blood is These are used to treat sudden hypotension due major blood loss till blood is

awaited.awaited.

   Precaution :Precaution : Before infusing sample for blood grouping and cross matching should be Before infusing sample for blood grouping and cross matching should be

collected.collected.

Colloids available :Colloids available :

Albumin 5% or 25% : Albumin 5% or 25% : Very effective in increasing Very effective in increasing intravascular vol. depletion secondary to blood loss.intravascular vol. depletion secondary to blood loss.

Dextran 40% :Dextran 40% : Effective but expensive plasma expander. Effective but expensive plasma expander. Contraindicated in pat with bleeding disorders or severe Contraindicated in pat with bleeding disorders or severe cardiac or renal failure.cardiac or renal failure.

Gelatin polymer : Gelatin polymer : It is a purified protein of animal collagen It is a purified protein of animal collagen origin.origin.

Hetastarch : Hetastarch : It is a synthetic colloid derived from corn starch.It is a synthetic colloid derived from corn starch. Plasma : Plasma : It is the most physiological plasma expander.It is the most physiological plasma expander.

Vol. of fluid replacement :Vol. of fluid replacement :

Q. How much fluid to give ?Q. How much fluid to give ? A. There is no fixed readymade formula, which can calculate A. There is no fixed readymade formula, which can calculate

fluid vol. in all pats. After consideration of all existing fluid vol. in all pats. After consideration of all existing parameters fluid vol. is calculated for each pat. individually. parameters fluid vol. is calculated for each pat. individually. Infusion of this fluid should be carried out under careful Infusion of this fluid should be carried out under careful observation to avoid under or over hydration.observation to avoid under or over hydration.

Apart from this, factors to be considered :Apart from this, factors to be considered : Age, weight, hydration status, vital data, preoperative and Age, weight, hydration status, vital data, preoperative and

intraoperative urine output, cardiac and renal status and type intraoperative urine output, cardiac and renal status and type of fluid to be replaced should be considered while calculating of fluid to be replaced should be considered while calculating fluid vol.fluid vol.

Guidelines for calculation :Guidelines for calculation : In adult pats. with no preexisting fluid deficit, amt. of In adult pats. with no preexisting fluid deficit, amt. of

intraoperative vol. can be roughly calculated as below :intraoperative vol. can be roughly calculated as below : Correction of fluid deficit due to starvation.Correction of fluid deficit due to starvation. Maintenance requirement for period of surgery.Maintenance requirement for period of surgery. Loss due to tissue dissection or haemorrhageLoss due to tissue dissection or haemorrhage

Vol. to be replaced for starvation fluid deficitVol. to be replaced for starvation fluid deficit = duration of = duration of starvation in hrs. starvation in hrs. ×× 2ml/ kg body weight. This deficit is 2ml/ kg body weight. This deficit is usually replaced with 5%D. The deficit may be replaced by usually replaced with 5%D. The deficit may be replaced by giving half of the calculated vol. in 1giving half of the calculated vol. in 1stst hr & the other half hr & the other half over next 2hrs in addition to the intraoperative fluid over next 2hrs in addition to the intraoperative fluid replacement.replacement.

Maintenance vol. for intraoperative periodMaintenance vol. for intraoperative period = duration of = duration of surgery in hrs surgery in hrs × × 2ml/kg body weight or rate of infusion = 2ml/kg body weight or rate of infusion = 2ml/kg body weight per hr.2ml/kg body weight per hr.

Usual fluid require to correct intraoperative fluid loss due to tissue Usual fluid require to correct intraoperative fluid loss due to tissue dissection or haemorrhage depends on the type of surgery viz :dissection or haemorrhage depends on the type of surgery viz :

   In Least surgical trauma – no fluid vol. replacement needed.In Least surgical trauma – no fluid vol. replacement needed. In Minimal surgical trauma like in tonsillectomy, SMR or In Minimal surgical trauma like in tonsillectomy, SMR or

septoplasty, they should receive 4ml/kg/hr fluid replacement. In septoplasty, they should receive 4ml/kg/hr fluid replacement. In addition maintenance fluid requirement is 2ml/kg/hr.addition maintenance fluid requirement is 2ml/kg/hr.

In Moderate surgical trauma = 6ml/kg/hr fluid replacement is In Moderate surgical trauma = 6ml/kg/hr fluid replacement is required.required.

In Severe surgical trauma like radical neck dissection, total hip In Severe surgical trauma like radical neck dissection, total hip replacement, pat should receive 10ml/kg/hr of fluid replacement replacement, pat should receive 10ml/kg/hr of fluid replacement plus 2ml/kg/hr maintenance fluid is required.plus 2ml/kg/hr maintenance fluid is required.

Blood transfusion :Blood transfusion : Intraoperative blood transfusion is often life saving and should be Intraoperative blood transfusion is often life saving and should be

used judiciously.used judiciously. Advantage :Advantage : It is the most physiological way to replace blood loss. As blood It is the most physiological way to replace blood loss. As blood

remains entirely in intravascular compartment, it is the best agent remains entirely in intravascular compartment, it is the best agent to correct hypotension secondary to blood loss. Blood transfusion to correct hypotension secondary to blood loss. Blood transfusion has added advantage to ensure adequate tissue oxygen delivery.has added advantage to ensure adequate tissue oxygen delivery.

Disadvantage :Disadvantage : Not readily available and needs time for cross matching , it has Not readily available and needs time for cross matching , it has

definite risk of transmitting infections like hepatitis, AIDS, malaria, definite risk of transmitting infections like hepatitis, AIDS, malaria, etc.etc.

Q. How to decide need of blood transfusion ?Q. How to decide need of blood transfusion ? A. Factors to be considered for intraoperative blood transfusion A. Factors to be considered for intraoperative blood transfusion

are :are : Preoperative Hb% - in normal adult pat. oxygen carrying capacity Preoperative Hb% - in normal adult pat. oxygen carrying capacity

is unaffected till it is as low as 8gm% & hematocrit 25%, provided is unaffected till it is as low as 8gm% & hematocrit 25%, provided there is no hypovolemia.there is no hypovolemia.

% loss of blood vol.% loss of blood vol. Others : vital data – hypotensive pat needs blood transfusion Others : vital data – hypotensive pat needs blood transfusion

even with lesser blood loss.even with lesser blood loss. Hydration status : hypovolemic pat. needs BT.Hydration status : hypovolemic pat. needs BT. Age : young adults tolerate blood loss better than old pat.Age : young adults tolerate blood loss better than old pat. Pat with IHD needs greater Hb for proper oxygenationPat with IHD needs greater Hb for proper oxygenation

Q. When not to give BT ?Q. When not to give BT ? A. It is unnecessary to replace blood loss of less than 500ml in A. It is unnecessary to replace blood loss of less than 500ml in

adult with normal preoperative Hb or loss of 10% of estimated adult with normal preoperative Hb or loss of 10% of estimated blood vol. is well tolerated. Such losses is replaced by RL or NS.blood vol. is well tolerated. Such losses is replaced by RL or NS.

As a rule blood loss needs to be replaced with 3times vol. of As a rule blood loss needs to be replaced with 3times vol. of crystalloids.crystalloids.

   Q. When to give BT intraoperatively ?Q. When to give BT intraoperatively ? A. Blood loss >20% of blood vol. needs BT, without considering A. Blood loss >20% of blood vol. needs BT, without considering

preoperative Hb status.preoperative Hb status. One unit of BT needed when blood loss is within 0.5L to 1L, BT is One unit of BT needed when blood loss is within 0.5L to 1L, BT is

necessary if Hb is likely to fall below 8gm% after blood loss.necessary if Hb is likely to fall below 8gm% after blood loss.

Post – operative fluid therapy :Post – operative fluid therapy :

The administration of fluid and electrolytes during the P.O. The administration of fluid and electrolytes during the P.O. period depends upon the clinical judgement of the patient’s period depends upon the clinical judgement of the patient’s status.status.

   Goal of fluid therapy :Goal of fluid therapy :

   The aim is to maintain reasonable BP >100/70 mmHg, The aim is to maintain reasonable BP >100/70 mmHg,

pulse rate less than 120beats/min and an hourly urine flow pulse rate less than 120beats/min and an hourly urine flow b/w 30 and 50ml with normal body temp., warm skin, b/w 30 and 50ml with normal body temp., warm skin, normal respiration and sensorium.normal respiration and sensorium.

Q. What factors should be consider before writing P.O. I/V Q. What factors should be consider before writing P.O. I/V fluid ?fluid ?

A. Following points to be consider :A. Following points to be consider : Age, weight, vital data, hydration status and urine output.Age, weight, vital data, hydration status and urine output. Preoperative diagnosis, nature of surgery and blood loss.Preoperative diagnosis, nature of surgery and blood loss. Nature and vol. of fluid and blood replaced intraoperatively.Nature and vol. of fluid and blood replaced intraoperatively. Drain output, nasogastric adpiration, fluid lost at injury site or Drain output, nasogastric adpiration, fluid lost at injury site or

operative site.operative site. Renal status, associated illness and associated electrolyte Renal status, associated illness and associated electrolyte

and acid base disorders.and acid base disorders. Loss due to atmospheric temp., pyrexia, hyperventilation.Loss due to atmospheric temp., pyrexia, hyperventilation.

Q. What are the routine P.O. orders of I/V fluid for first 3 Q. What are the routine P.O. orders of I/V fluid for first 3 days ?days ?

A. Usual prescription of P.O. I/V fluid in NPO pats. is :A. Usual prescription of P.O. I/V fluid in NPO pats. is :

For 1For 1stst 24 hrs of surgery : 24 hrs of surgery :

2L 5%D or 1.5 L 5%D 2L 5%D or 1.5 L 5%D + + 0.5L isotonic saline.0.5L isotonic saline. 22ndnd P.O. day : 2L of 5%D P.O. day : 2L of 5%D ++ 1L of NS 1L of NS 33rdrd P.O. day : similar fluid P.O. day : similar fluid ++ 40 – 60 mEq K /day. 40 – 60 mEq K /day.

Q. Why usually K is avoided in I/V fluids for first 2 PO days ?Q. Why usually K is avoided in I/V fluids for first 2 PO days ?

A. It is avoided because :A. It is avoided because : Pats may have oliguria or azotemia. So till urine output is Pats may have oliguria or azotemia. So till urine output is

established and normal renal status is ensured, K established and normal renal status is ensured, K supplementation can be risky.supplementation can be risky.

PO tissue trauma may release K from IC to EC compartment, PO tissue trauma may release K from IC to EC compartment, which may cause ↑K.which may cause ↑K.

Intraoperative or post operative transfusion of stored blood or Intraoperative or post operative transfusion of stored blood or haemolysed blood may add large amt. of K.haemolysed blood may add large amt. of K.

PO metabolic acidosis will shift IC K to extracellularly.PO metabolic acidosis will shift IC K to extracellularly. As body has large store of K intracellularly ↓K will not occur.As body has large store of K intracellularly ↓K will not occur.

Q. How long to infuse I/V fluid Post operatively?Q. How long to infuse I/V fluid Post operatively? A. It is a wrong method to infuse total I/V fluids within 8 to 12 hrs in PO A. It is a wrong method to infuse total I/V fluids within 8 to 12 hrs in PO

period and not giving any infusion in rest of the period. Maintenance fluids period and not giving any infusion in rest of the period. Maintenance fluids should be administered at a steady rate over an 18 to 24 hr period. If should be administered at a steady rate over an 18 to 24 hr period. If given over a short period, renal excretion of the excess salt and water given over a short period, renal excretion of the excess salt and water may occur. But as the normal losses continue over the full 24 hr period, may occur. But as the normal losses continue over the full 24 hr period, body will be deprived of their fluid need during the remaining period.body will be deprived of their fluid need during the remaining period.

Q. Which fluids should be given to replace additional losses in PO pats. ?Q. Which fluids should be given to replace additional losses in PO pats. ?

A. For prolonged vomiting and nasogastric suction : fluid of choice is NS.A. For prolonged vomiting and nasogastric suction : fluid of choice is NS. For blood loss : if vol is less, replacement is done with 3 times vol of For blood loss : if vol is less, replacement is done with 3 times vol of

isotonic saline or RL, but if the loss is greater, we have to think about BT.isotonic saline or RL, but if the loss is greater, we have to think about BT.

Thank youThank you