1. Percutaneous Endoscopic Gastrostomy (S-16) (Pg. 97) 2. TPN* - complications* (S-15)(S-14) (Pg. 98) 3. Assessment of Nutritional Status (W-10) 4. Metabolic Alkalosis (S-10) (Pg. 90) 5. Hypokalemia (S-09) (Pg. 89) 6. Enteral Nutrition (W-03) (Pg. 96) Clinical mc and assessment of sev injured • Enteral and TPN • Answer these questions and make notes in easy language from the context given below Normal Physiology Total body water is 60% of body weight in males, 50% of body weight in females, i.e. 30 litres. x x Intracellular water—20 litres (2/3). x x Extracellular water—10 litres (1/3).   Plasma (1/4) (2.5 litres).   Interstitial fluid (7.5 litres). Ion ICF ECF and plasma Sodium 10 mmol/L 140 mmol/L Potassium 150 mmol/L 4.5 mmol/L Chloride Trace only 105 mmol/L ECF volume and osmolality regulation is controlled by three hormones. Aldosterone, ADH, atrial natriuretic hormone. WATER loss (VolUME loss) It is decrease in the whole body fluid volume which includes both ECF and ICF. It is usually ECF loss which is more important and assessed. It can be isotonic volume depletion with both salt and water loss leading into hypovolaemia, or only water loss with only minimal loss of electrolytes leading into dehydration. Causes and Features x x Isotonic volume depletion occurs due to diarrhoea, vomiting, and excess diuresis. Here normal or decreased sodium is observed. Fluid loss is only of ECF and so early intravascular volume reduction occurs. This causes hypotension and decreased tissue perfusion. Features are—dry tongue, rapid pulse, cold clammy extremities, sunken eyes, hypotension, oliguria, raised blood urea, decreased urinary sodium. Hypovolaemia can be mild (< 2l fluid loss); moderate (2–3 L fluid loss); severe (>3 L fluid loss). x x Only pure water loss occurs due to poor fluid intake and diabetes insipidus. It causes dehydration with proportionate decrease in total body water (2/3rd ICF, 1/3rd ECF). As ECF including intravascular fluid loss is less, hypotension is less. Features here are—severe thirst, confusion and convulsions due to hypernatraemia; blood pressure is relatively normal. Dehydration can be mild (weight loss 5%); moderate (10%); severe (15%). Management x x Evaluation is done by doing serum sodium, urinary sodium, and blood urea. x x Isotonic volume depletion is corrected by 0.9% normal saline. x x Pure water depletion is corrected by more water intake/ intravenous 5% dextrose. x x Monitoring fluid therapy by skin and tongue examination, weight gain, pulse, blood pressure, CVP, PCWP. WATER EXCEss (ECF VolUME EXCEss) It can be divided into water and salt excess or predominantly water excess called as water intoxication. Water and salt excess occurs in CCF, cirrhosis, nephrotic syndrome, hypoproteinaemia, renal failure, excessive saline infusion. Water intoxication occurs in TURP, excess infusion of 5% dextrose only, SIADH secretion, psychogenic polydypsia. It is managed by stopping fluid infusion or procedure (TURP); fluid restriction, and treating the cause. Causes x x Excessive amount of intravenous dextrose (5%). x x During colorectal bowel wash for preparation of large bowel for surgery, if water is used instead of saline, especially in children. x In TURP (Transurethral resection of prostate) when excess x irrigating fluid water or glycine is used (commonly used). x x In syndrome of inappropriate antidiuretic hor­ mone (SIADH) which is commonly associated with lobar pneumonia, empyema, oat cell carcinoma and head injury. Clinical features ™ ™ Drowsiness, weakness ™ ™ Convulsions and coma ™ ™ Nausea, vomiting ™ ™ Passage of dilute urine ™ ™ Distended neck veins ™ ™ Pedal oedema ™ ™ Gain in body weight—most sensitive and consistent sign ™ ™ Circulatory overload—tachycardia, pulmonary oedema, hyper- tension ™ ™ Bilateral basal crepitations, ascites ™ ™ Raised CVP, PCWP Electrolyte and Nutrition 93 Investigations x x Haematocrit and sodium level (will show fall in level). x x Low potassium. Low blood urea. Treatment x x Water and salt restriction and observation. x x Monitoring in ICU. x x Management of fluid and electrolyte balance. x x Infusion of hypotonic sodium chloride. Administration of diuretics and hypertonic saline should be avoided, as it may cause rapid changes in serum sodium and water level which will lead to neuronal demyelination and fatal outcome. ECF loss x x Here only ECF loss is present with normal ICF. x x It is seen in vomiting, diarrhoea, intestinal obstruction. x x Treatment is infusion of normal saline. diarrhoea, vomiting, wherein urine sodium level is less than 20 mmol/l; due to diuresis or renal causes wherein urine sodium level is more than 20 mmol/l or it may be due to correction of hypovolaemia using hypotonic fluid like 5% dextrose. Condi- tion can be treated well using isotonic normal saline. x x Normovolaemic hyponatraemia: It may be due to renal failure or syndrome of inappropriate ADH secretion (SIADH). In mild asymptomatic patients it is corrected by fluid restriction (1 l/day will raise the serum Na). Vaso- pressin antagonist demeclocycline which increases the diluting ability of kidney is used in severe cases. x x Pseudohyponatraemia: Plasma osmolality is mainly achieved by serum sodium; but small proportion, i.e. 25% of osmolality is due to other solutes like glucose, lipids, plasma proteins, urea which will not move easily between intracellular and extracellular spaces. When concentration of these molecules raise due to some pathology, proportionately relative concentration of sodium will drop causing pseudo- hyponatraemia. Here condition causing related to specific solutes mentioned above is treated, than hyponatraemia. Causes x x Intestinal obstruction. x x Intestinal fistulas—biliary, duodenal, gastric, pancreatic. x x Gastric outlet obstruction with severe vomiting. x x Ryle’s tube aspiration. x x Severe diarrhoea due to viral cause, in colitis, colorectal polyps. x x Syndrome of inappropriate antidiuretic hormone (SIADH). x x Immediately after surgery and trauma, sodium depletion occurs. x x Stroke. ECF EXCEss x x Only ECF excess without an ICF excess. x x Excessive infusion of saline with impaired excretion. x x Raised JVP (earliest and best clinical sign), cardiac failure and peripheral oedema. x x Treatment is fluid restriction and diuretics like frusemide. hyPONATraEmia Sodium level less than 130 mEq/l. Hyponatraemia is said to be severe if serum sodium becomes lesser than 100 mEq/l in acute type; and lesser than 115 mEq/l in chronic type. It can be due to water overload (dilutional) or sodium loss. Types of Hyponatraemia x x Acute—presents as neurological manifestations. x Chronic—causes pontine myelinolysis. It presents as x behavioural changes, progressive weakness, and cranial nerve palsies. Types also may be: x x Hypervolaemic hyponatraemia wherein rapid absorption of fluid occurs into intravascular compartment leading into pulmonary and cerebral oedema. It is due to decreased osmo- lality causing movement of ECF into the cells. Serum sodium level lesser than 100 mmol/l is called as severe hyponatraemia, causes convulsions. Here urinary sodium will be less than 15 mmol/l. Acute hyponatraemia is corrected by fluid restriction, hypertonic saline, loop diuretics like frusemide. Monitoring the serum sodium level of the patient is essential. Sodium should be corrected up to above the level of 125 mmol/l. Correction should be slow and gradual at a rate of 2 mEq/l/h with up to 20 mEq/l correction in 24 hours with 4th hourly assessment of serum sodium. Overcorrection of sodium should not be done. Rapid correction can lead into irreversible myelin lysis of pontine. x x Hypovolaemic hyponatraemia: It is due to hypovolaemia by Clinical features ™ ™ Dry coated tongue ™ ™ Sunken eyes ™ ™ Dry wrinkled skin ™ ™ Hypotension ™ ™ Dark scanty urine ™ ™ Irritability, disorientation and neurological manifestations ™ ™ Convulsions ™ ™ In chronic hyponatraemia—hypothermia, reduced tendon reflexes, pseudobulbar pasly Investigations x x Serum electrolytes. Urinary sodium is low. x x Sodium deficit is calculated by: (125 – present serum sodium) × body weight in kg × 0.6. Treatment x x Intravenous infusion of normal saline as a slow and gradual correction at a rate of 2 mEq/L/hour in acute cases and < 1 mEq/L/hour in chronic cases. Correction should not exceed more than 20 mEq/L/day in acute cases and more than 10 mEq/L/day in chronic cases. Hypertonic saline of 1.6% or 3% also can be used in severe cases. 0.9% normal saline contains 154 mEq of NaCl; 3% saline contains 500 mEq of NaCl. x x The cause is treated. You cannot harm a bandaged wound.— Croatian Proverb 94 SRB's Manual of Surgery hyPERNATraEmia Serum sodium level > 150 mEq/L. Excess infusion of normal saline causes overload in circulating salt and water. It is usually due to water deficit. Causes x x Renal dysfunction. x x Cardiac failure. x x Drug induced like NSAID, corticosteroids. It may be either primary sodium excess or primary potas- sium excess or primary water deficit. Types of Hypernatraemia x x Euvolemic (pure water loss): It is due to failure of water intake like in comatous patients, bedridden people, post- operative patients and in patients with high fever leading into extrarenal loss of water. It can occur in diabetes insipidus or chronic renal failure as renal loss of water. x x Hypovolaemic (among loss of water and sodium, more water is lost than sodium): It is due to vomiting, diarrhoea, more undue sweating (extrarenal); osmotic diuresis by glucose/ mannitol (renal). x x Hypervolaemic (both sodium and water gain but sodium gain is more than water gain) as seen in more salt intake, excess steroids, sodium bicarbonate/hypertonic saline infu- sion (salt gain). Clinical Features x x Pitting oedema. x x Puffiness of face. x x Increased urination. x x Often dilated jugular veins. x x Features of pulmonary oedema. Investigation x x Serum electrolytes, plasma and urine osmolality, renal func- tion tests, haematocrit. Management x x Restriction of saline and sodium. Treatment of pulmonary oedema. x x Hypernatraemia should be corrected slowly as follows:   Initial infusion of normal saline, then infusion of half strength saline (0.45%) and later with 5% dextrose, i.e. gradual controlled correction is done. Otherwise cerebral oedema and hyperglycaemia can develop.   Oral and nasogastric administration of water/fluids. hyPOKalaEmia Sudden Hypokalaemia Serum potassium level less than 3.5 mEq/l. It occurs in patients in diabetic coma treated by insulin and saline infusion. Gradual Hypokalaemia Causes x x Diarrhoea of any causes, villous tumour of the rectum, ulcerative colitis. x x After trauma or surgery. x x Pyloric stenosis with gastric outlet obstruction. x x Duodenal fistula, ileostomy. x x After ureterosigmoidostomy. x x Insulin therapy. x x Poisoning. x x Drugs like beta agonists. x x Familial periodic paralysis. Clinical Features x x Slurred speech. x x Muscular hypotonia—physical sign. x x Depressed reflexes. x x Paralytic ileus. x x Weakness of respiratory muscles. x x Cardiac arrhythmias. x x Inability to produce concentrated urine and so causes nocturia and polyuria. ECG shows prolonged QT interval, depression of the ST segment and inversion of T wave, prominent U wave. Often hypokalaemia is associated with alkalosis. Serum potassium will be decreased. Treatment x x Oral potassium 2 g 6th hourly, 15 ml potassium chloride syrup (20 mmol of K). x x IV KCl 40 mmol/litre given in 5% dextrose or nor­ mal saline slowly, often under ECG monitoring [Total dose is 40 mmol (0.2 mmol /kg/hour). Maximum dose per hour is 20 mmol]. x x Hypokalaemic alkalosis which occurs in pyloric stenosis should be treated carefully by IV potassium as there will be severe potassium loss. hyPERKalaEmia Normal range of potassium is 4.0 to 4.5 mEq/l. Hyperkalaemia manifests when potassium exceeds 6 mEq/l. Causes x x Renal failure. x x Rapid infusion of potassium. x x Transfusion of stored blood. x x Diabetic ketoacidosis. x x Adrenal insufficiency. x x Potassium sparing diuretics, cyclosporine, beta blockers. x x Metabolic acidosis. Electrolyte and Nutrition 95 x x Insulin deficiency. x x Tissue destruction, burns, trauma, tumour necrosis, crush injury. x x In vitro haemolysis, thrombocytosis, tourniquet application, exercise—pseudohyperkalaemia. x x Familial hyperkalaemic periodic paralysis. Potassium excess is a dangerous condition which can cause sudden cardiac arrest. Investigations High serum potassium level. Peak ‘T’ wave in an ECG. Treatment x x IV administration of 50 ml of 50% glucose with 10 units of soluble insulin, slowly. x x Infusion of 10% calcium gluconate (as cardio­ protection) intravenously. x x Calcium chloride is given in severe cases as calcium in this form is released immediately without hepatic metabolism. x x Diuresis using frusemide injection. x x Haemodialysis when required—very useful. x x Continuous ECG monitoring is a must. x x Polyesterene sulphonate ion exchange resin 30 g/hour in 50 ml of 70% sorbitol as an enema. x x Salbutamol nebulisation or intravenously 0.5 mg in 4 ml of saline/Albuterol nebulisation. x x IV sodium bicarbonate—shifts potassium in to cells. 7.5%, with 50–100 ml intravenously in 10 minutes. hyPErmagNEsaEmia It is rare. Serum magnesium > 2.5 mEq/l. Normal serum magnesium is 1.5–2.5 mEq/l and intra-cellular magnesium which is more (2nd higher) is 26 mEq/l. Magnesium is mainly deposited in bone (60%). It is a cofactor for many enzymes necessary in phosphorylation of glucose in the cell and ATP utilisa- tion in muscle fiber. Daily required dietary intake of magnesium is 0.4 gram. It is reabsorbed well in proximal renal tubule. Causes x x Advanced renal failure treated with magnesium containing antacids, diabetic ketoacidosis. x x Intentionally produced hypermagnesaemia while treating pre­ eclampsia. Clinical Features x x Loss of tendon reflexes (most common). x x Neuromuscular depression. x x Flaccid quadriplegia. x x Respiratory paralysis. x x Somnolence. x x Hypotension. hyPomagNEsaEmia x x Serum magnesium <1.5 mEq/l. Causes x x Malnutrition, alcohol. x x Large GI fluid loss. x x Patients on total parenteral nutrition. Clinical Features x x Hyperreflexia. x x Muscle spasm. x x Paraesthesia. x x Tetany. x x It mimics hypocalcaemia. It is often associated with hypokalaemia and hypo­ calcaemia. Treatment Two gram (16 mEq) of magnesium sulphate slow intravenously, in 10 minutes. Later maintenance dose of 1 mEq/kg/day as slow continuous infusion is given/oral magnesium is needed. ACID-BasE BalaNCE Normal pH (– log 10 of H+) is 7.36–7.44. Factors which control the pH ™ ™ Buffer system – Bicarbonate buffer – – Protein buffer – – Phosphate buffer – ™ ™ Renal control of pH ™ ™ Respiratory control of pH Note: When H+ increases pH decreases. An acid is a substance that dissociates water to release hydrogen ion. A base is a substance that takes hydrogen ion. A buffer is a combination of weak acid and conjugate base. These buffers main- tain the H+ concentration in blood within fine limits. Natural buffers are extracellular or intracellular. Bicarbonate/carbonic acid buffer, phosphate buffer and plasma proteins are extracellular natural buffers. Haemoglobin and other proteins are intracellular buffers. Bicarbonate/ carbonic acid buffer is most important as carbonic acid levels are regulated by lungs which eliminates excess of it as CO2. Bicarbonate part is separately controlled by kidney. Acidosis is pH of blood less than 7.35. Alkalosis is pH more than 7.45. Henderson Equation (Used to Assess Hydrogen Ion Concentration) H+ (nmol/L) = K × H CO 2 3 HCO 3 mmol/L mmol/L− Sir, it is plain that if he is too fat he has eaten more than he should have done.— Samuel Johnson 96 SRB's Manual of Surgery OR K × HCO α PCO 2 − mmol/L 3 – Here constant K is 800 (for H2CO3 / HCO3 buffer). Carbonic acid (H2CO3) is solubility coefficient of CO2 in blood (α) multiplied by partial pressure of CO2 (PCO2). α is 0.03 ml/mmHg/100 ml of blood; PCO2 is 40 mmHg. H2CO3 = αPCO2 = 0.03 × 40 = 1.2 ml. Normal blood bicarbonate/ HCO3 level is 24 mmol/L. so H+ is 800 × 1.2 divided by 24 = 40 mmol/L. Henderson-Hasselbalch Equation (Used to Assess pH) It is used to find out pH of the blood using logarithm. Negative logarithm of constant K (800 for carbonic buffer) is called as – pKa. It is 6.1 for H2CO3/HCO3 buffer system. − pH = pKa + log HCO 3 means 6.1 + log 24 divided by 1.2 = 6.1 H CO 2 3 + log 20 = 6.1 + 1.3 = 7.4 METABoliC alKalosis – Primary base excess, i.e. HCO3 . A standard bicarbonate above 27 mmol/litre. Causes x x Repeated vomiting due to any cause. Commonly seen in cases of pyloric stenosis. Here hypokalae­ mic alkalosis occurs which is an important aspect for managing the patient. x x Excess alkali ingestion, e.g. antacids. x x Cortisol excess either due to over administration or Cush- ing’s syndrome. Clinical Features x x Cheyne stokes breathing with period of apnoea of 5–30 seconds. x x Tetany due to alkalosis. More often latent tetany which is revealed by Trousseau’s sign. Investigations Serum electrolytes, arterial blood gas analysis. Treatment x x Normal saline or double strength normal saline IV infusion, with slow IV potassium chloride 40 mmol/litre in saline, slowly under ECG monitoring. x x pH more than 7.7 causes life-threatening alkalosis which requires rapid correction by infusing dilute hydrochloric acid or ammonium chloride, however, with care and monitoring. RESPiraTory alKalosis Arterial PCO2 is below normal. Causes x x Hyperventilation during anaesthesia, due to head injury/ severe pain. x x High altitude. x x Hyperpyrexia. x x Encephalitis, hypothalamic tumours, drugs like salicylates, due to cirrhosis of liver. x x Hysteria. Features and Management x x Headache, tingling, circumoral anaesthesia, tightness in chest, tetany, arrhythmias are the features. x x Low PaCO2, low HCO3, high alkaline pH are typical. Serum HCO3 will not fall below 15 mEq/L. x x It can be acute or chronic. x x It is managed by oxygen therapy, treating the cause, aceta- zolamide in high altitude. x x Respiratory suppression due to alkalosis is treated by CO2. METABoliC ACIDosis It is an excess acid or base deficit. A standard bicar­ bonate below 21 mmol/litre. Causes Increase in fixed acid: x x Diabetic ketoacidosis. x x Starvation. x x Hypoxia. x x Renal insufficiency. x x Cardiac arrest. x x Excessive exercise. x x Intestinal strangulation. Here anion gap is increa­ sed. Loss of base: x x Diarrhoea. x x Ulcerative colitis. x x Gastrocolic fistula. x x Intestinal fistula. x x Ureterosigmoidostomy causes hyperchloraemic hypokalaemic acidosis. Here anion gap is normal. Features x x Rapid, deep, noisy breathing (air-hunger)—Kussmaul’s breathing. x x Cold clammy skin, tachycardia, right heart strain, altered level of consciousness. x x Cardiac arrhythmias, hypotension. x x Anorexia, muscle weakness, vomiting. x x pH below 7.2 is dangerous and life-threatening. x x Capillary stasis. x x Urine is strongly acidic. x x Low standard HCO3 level. x x Base deficit. Increased anion gap is seen in Normal anion gap is seen in • Metabolic acidosis due to ketoacidosis • Lactic acidosis • GIT fistulae • Poisoning • Hyperchloraemic acidosis • Renal failure x x It is evaluated by doing arterial blood gas analysis (ABG) which shows low HCO3, low pH; anion gap; urinary anion gap (UAG). Normal UAG is zero or positive. In metabolic acidosis due to GI cause, UAG becomes negative due to increased NH4Cl excretion; if it is due to renal cause, UAG will be positive. Treatment x x Correction of hypoxia. x x 50 mmol of 8.4% sodium bicarbonate infusion IV. Sodium bicarbonate required in mEq/L = Body weight in kg × Base deficit × 0.3. x x Correction of electrolytes. x x Specific treatment for lactic acidosis (type A [shock / respira- tory/CO/cyanide/anaemia]; type B [diabetes/hepatic/toxins/ drugs])—only careful use of NaHCO3 in severe cases, dichloracetate which stimulates pyruate dehydrogenase to reduce lactate. x x Specific therapies for diabetic ketoacidosis, alcoholic acidosis, aspirin poisoning, renal causes. Astrup formula Total base excess or deficit = Base excess/base deficit × body weight in kg × 0.3 RESPiraTory ACIDosis It is a feature of respiratory failure with high arterial PCO2 causing fall in pH. Causes x x During and after anaesthesia. x x Chronic bronchitis. x x Emphysema. x x Thoracic diseases. x x Upper abdominal surgeries and diseases. x x Respiratory airway obstruction. x x Myasthenia gravis. x x Poliomyelitis. x x Stroke, infection, obesity, hypoventilation. Features and Treatment x x Features of hypercapnia like dyspnoea, confusion, psychosis, hallucinations, sleep disturbances, tremor, jerks, and personality changes. CNS manifestations are more severe in respiratory acidosis than in metabolic acidosis as lipid soluble CO2 crosses blood-brain barrier easily than HCO3. x x Acute respiratory acidosis is managed by oxygen therapy, ventilator support. Oxygen therapy should not be used in chronic hypercapnoea unless it is really indicated as hypoxia stimulated respiration may be suppressed. Alkali therapy Electrolyte and Nutrition 97 also is not usually used unless acidosis is very severe (below 7.15) or there is severe bronchospasm. ANioN gaP x x It is calculated estimation of the undetermined or unmeasured anions in the blood. x x It is (Na+ + K+) — (HCO3 ¯ + Cl¯). x x Normal anion gap is 10-16 mmol/litre. x x Anion gap is charge difference between unmeasured anion and cation. Important unmeasured anions are anionic protein, phos- phate, sulphate, organic acids. Unmeasured cations are calcium and magnesium. Albumin is the main component of anion gap. When albumin decreases by one g/dl then anion gap decreases by 2 mEq/L. • Diarrhoea FLUID THEraPY Osmolality of a solution is assessed by the amount of solute dissolved in a solvent like water measured in weight (kg). Osmolarity of a solution is assessed by the amount of solute dissolved in a solvent like water measured in volume (litre). Normal plasma Osmolality is 285 mOsm/kg (275–295). Osmolality is calculated by two methods . a. Osmolality of plasma = 0 54 × 103 mOsm/kg 1 86 . It is based on the fact that solution of 1 mOsmol/kg freezes at – 1.86°C; whereas normal plasma freezes at – 0.54°C. Glucose mg % Blood urea mg % b. Osmolality of plasma = 2 × (Na) + ( ) ( ) + 18 6 It is based on the concentrations of major solutes in plasma. So sodium concentration contributes mainly to the osmolality. Colloidal osmotic pressure is difference in plasma osmotic pres- sure and interstitial fluid pressure which is normally 25 mm Hg, which is mainly by plasma albumin concentration. Plasma proteins do not go out of capillary wall into the interstitium. Principles of Fluid Therapy Indications x x For rapid restoration of fluid and electrolytes in dehydration due to vomiting, diarrhoea, shock due to haemorrhage or sepsis or burns. x x Total parenteral nutrition. x x Anaphylaxis, cardiac arrest, hypoxia. x x Post-gastrointestinal surgeries. x x For maintenance, replacement of loss or as a special fluid. Advantage Controlled, accurate and adjustable, rapid and predictable. Less you eat, you are malnourished. More you eat, more you are diseased. 98 SRB's Manual of Surgery Problems in Fluid Therapy x x Needs hospitalisation; costly; needs asepsis. x x Fluid overload; pulmonary oedema and cardiac failure; infection. x x Thrombophlebitis; haematoma; cellulitis in local area. x x Pyrogenic reaction; air embolism; bacteraemia. x x Discomfort; poor patient acceptance. Daily requirement of sodium is 100 mEq; potassium is 60 mEq; calcium is 5 mEq; magnesium 1 mEq. One litre of normal isotonic saline contains 154 mEq of sodium. Ringer’s lactate is the most physiological fluid (crystalloid) containing sodium—130 mEq/lt; potassium—4 mEq/lt; chloride—109 mEq/lt; lactate (bicarbonate)—28 mEq/lt; and calcium—3 mEq/lt. It should be avoided in liver failure patients. As it does not contain glucose it can be used in diabetics. Other crystalloid fluids—normal saline, dextrose saline, 5% dextrose, isolyte P, isolyte G, isolyte M. Colloids are of large molecules which shift the fluid from interstitial compartment to intravascular compartment and are used as plasma expanders. Haemaccel, hetastarch, pentastarch, dextran 40/70 are colloids. Special purpose fluids are sodium bicarbonate 7.5% and 8.4% used in metabolic acidosis, forced diuresis, hyperkalaemia; mannitol 10/20% used as an osmotic diuretic agent; hypertonic saline 1.6%, 3%, 5% and 7.5% used in hyponatraemia of different severity; albumin 4.5% as plasma expander; albumin 20% in severe hypoalbuminaemia. Calculation of Drop Rate of IV Fluids 1 ml =16 drops in usual drip set. For microdrip set one ml = 60 drops. a. Quantity of fluid required in liters per day × 10 = Drop rate/minute. 2.5 litres is usually used quantity of fluid/day. So 2.5 × 10 = 25 drops/minute. b. Fluid volume in ml to be infused in one hour divided by four = Number of drops/minute. Example: 100 ml/hour means 25 drops/ minute. c. Number of microdrop/minute = Volume in ml/hour (50 microdrop/ minute = 50 ml/hour). Note: • Weight loss more than 10% of individual’s weight in 6 months is called as significant weight loss. • Body mass index (BMI) is body weight in kilograms divided by height in meters squared. BMI less than 18.5 signifies nutritional impairment and below 15 signifies severe malnutrition. • Daily fluid loss from kidneys is 1500 ml; from lungs is 400 ml; from skin is 800 ml; from stool is 60–150 ml. • Energy requirement per day is 20–30 kcal/kg, i.e. around 2000 kcal/ day total. • Glucose requirement is 200 g per day; fat requirement is 200 g per week; nitrogen (protein) requirement is 0.15 g/kg per day. Nitrogen need increases to 0.25 g/kg/day in hypercatabolic status. • Transit time is rapid in jejunum; three times slower in ileum; still slower in colon. • Fluid absorption capacity is 40% in jejunum; 70% in ileum; 90% in colon. • Electrolyte and vitamin B12 absorption and enterohepatic circula- tion occurs in ileum and so ileum is more important than jejunum. Crystalloids Crystalloids are aqueous solutions of mineral salts or other water soluble molecules. They are used mainly to improve the volume and electrolyte supplementation. Type Content 5% Dextrose One litre contains 50 gram of glucose. It is hypotonic; pH is 4.5; provides 170 kcal/l Normal saline (isotonic saline— 0.9% NaCl/ NS). 3% normal saline (hypertonic) contains 513 mEq/litre of sodium; is used in hyponatraemia due to SIADH or water intoxication or severe hyponatraemia Crystalloids commonly used Indications Contraindications and problems Used in pre- and post-operative fluid therapy; 5% and 10% dextrose is used as protector of liver in obstructive jaundice, pre-operative preparation in biliopancreatic surgeries, clear toxic substances. It is useful in correction of hypernatraemia due to pure water loss like diabetes insipidus, excess use of electrolytes; 5% dextrose is infused with frusemide. One litre contains 154 mEq each of sodium and chloride. • It mainly exists in ECF to maintain osmolality; it increases the intravascular volume and is so very useful to stabilize the blood pressure in hypovolaemia. • It is used in diarrhoea, vomiting, excessive sweating; in treatment of alkalosis; in hyponatraemia; diabetic ketoacidosis; hypercalcaemia; brain surgery and injuries. • It is used in giving wash to body cavities like peritoneum or any wounds (warm NS). Cerebral oedema as it is hypotonic; cranial surgeries; stroke; hypovolaemic shock as it may cause hyperglycaemia and osmotic diuresis; hyponatraemia; water intoxication; it should not be used for rapid correction of hypernatraemia; diabetes and hyperglycaemia. Note: Intravenous administration of dextrose can cause low potassium, magnesium and phosphate; and causes thrombophlebitis. • It is avoided in hypertension, pre-eclampsia, elderly, dehydration with hypokalaemia. • Large volume infusion may cause sodium retention and hyperchloraemia. Contd... Electrolyte and Nutrition 99 Contd... One litre contains 50 grams of glucose, 154 mEq each of sodium and chloride; pH 4.2; osmolarity 585 mOsm/litre. One litre contains 50 grams of glucose; 77 mEq each of sodium and chloride. One litre contains 130 mEq sodium (as sodium lactate); 109 mEq of chloride; 4 mEq potassium; 28 mEq of bicarbonate; 3 mEq of calcium. It is devoid of glucose. grams of glucose; 40 mEq sodium; 38 mEq chloride; 35 mEq potassium; 15 mEq phosphate; 20 mEq acetate. grams of glucose, 63 mEq of sodium, 130 mEq of chloride, 17 mEq of potassium, 69 mEq of ammonium. • Gastric juice contains nearly similar contents of Isolyte G. In liver ammonium converts into urea and hydrogen ion. Hydrogen ion neutralizes alkalosis. One litre contains 50 grams of glucose; 140 mEq of sodium; 103 mEq of chloride; 5 mEq of calcium; 10 mEq of potassium; 47 mEq of magnesium; 3 mEq of acetate; 8 mEq of citrate. It corrects hypovolaemia and hyponatraemia. It is used alkalosis due to vomiting and nasogastric aspiration. It is commonly used in fluid therapy; treatment of severe hypernatraemia as it corrects it gently; to avoid cerebral oedema. It is used in maintenance therapy and in post-operative period. • It is used in corrections of severe hypovolaemia as it expands intravascular volume rapidly. • It is useful in managing metabolic acidosis as lactate in liver is metabolized to bicarbonate. • It is useful fluid for therapy in post- operative period, burns, diarrhoea. It also corrects hypokalaemia. It maintains normal ECF fluid and electrolyte balance. • In diabetic ketoacidosis it provides glucose free fluid. • It gives calories, water, electrolytes, pH. Rich potassium in it is useful in correcting the hypokalaemia provided renal function is good. It can correct acidosis also. • It is useful in diarrhoea, bilious vomiting. Gastric juice vomiting or continuous nasogastric aspiration which causes hypochloraemic, hypokalaemic, metabolic alkalosis which is corrected by Isolyte G. It is used mainly to replace extracellular fluid. It contains double the ECF concentrations of potassium and acetate (rest similar). It gives energy, water, magnesium, corrects acidosis. It is used in fluid therapy in paediatric age group. It is not used in cardiac and renal failure. Used in shock but not used in severe hypovolaemic shock. It is not used in hyponatraemia, and in diarrhoea and vomiting. • It can cause lactic acidosis, so contraindicated in hypoxia, severe shock, liver diseases, in vomiting and nasogastric aspiration, in metabolic alkalosis. • It cannot be used along with blood transfusion as calcium in Ringer lactate can bind with citrate of transfusing blood precipitating clotting of the donor blood. Blood products and RL cannot be infused simultaneously. It is not useful in correcting hyponatraemia as sodium concentration in it is low. It is not used in metabolic alkalosis due to vomiting, due to diuretics. It is not used in hyponatraemia, renal failure, hyperkalaemia, hypovolaemic shock. • Many drugs are given using NS as vehicle. • It is safer in renal failure as it does not contain potassium. Dextrose (5%) with normal saline (0.9 NaCl), (DNS) Dextrose with 0.45% normal saline Ringer’s lactate (Hartmann’s/ balanced salt) solution Isolyte M (Maintenance) One litre contains 50 Isolyte G (gastric) • One litre contains 50 Isolyte E (Extracellular replacement) Isolyte P (paediatric) One litre contains 50 grams of glucose; 25 mEq of sodium; 22 mEq of chloride; 20 mEq of potassium; 3 mEq of magnesium; 23 mEq of acetate. Life will give you back everything you have given to it. 100 SRB's Manual of Surgery Colloids Colloids are of up to 20 u sized large molecules, which retain in the intravascular space for longer time and so raise the intra- vascular volume (3 times > than crystalloids). They improve cardiac output but not oxygen carrying capacity. Colloids should maintain oncotic pressure equal to that of plasma; should be stable and inert; non-toxic, non-antigenic, non-pyrogenic; should be easily sterilisable; should not interfere with blood grouping. Colloid Albumin (Heat treated human albumin) It maintains 75% of plasma oncotic pressure. It is the vehicle to transport many low molecular substances including drugs. Dextran Bacteria (Leuconostoc mesenteroides and streptococcus mutans) incubated in sucrose media producing complex branched glucan polymers as dextrans. Haemaccel 500 ml bottle with active ingredient polygeline. Colloids commonly used content Indications Problems • 5% human albumin (50 grams/L) has colloid osmotic pressure of 20 mm of Hg (that of plasma pressure); its effects last for 18 hours. It increases the volume 1:1. • 25% human albumin (250 grams/L) has got colloid osmotic pressure of 70 mm Hg; expands the intravascular volume 5 times more by shifting the fluid from extravascular (interstitial) space to intravascular space; should not be used in hypovolaemia. • Dextran is first discovered by Louis Pasteur in wine. • It is used to expand intravascular volume. • Dextran 70 has got molecular weight of 70,000. Its excretion through kidney is poorer and so remains in the blood for weeks. It is used as 6% solution. • Dextran 40 has got molecular weight of 40, 000. It is used as 10% solution; its action is faster but shorter than dextan 70 due to faster excretion through kidney compared to dextran 70. • 1000 ml of hamaccel contains polypeptides of degraded gelatin (origin—bovine bone; cross linked via urea bridges), 35 grams (equivalent of 6.3 gram of nitrogen). • It also contains sodium and chloride of 145 mmol (0.85 gram); calcium 6.25 mmol (0.25 gram); potassium 5.1 mmol (0.20 gram); traces of phosphate, sulphate and anionic polypeptides. Its molecular weight is 30,000 with 1.7 viscosity. • Hamaccel should be stored in 2–25°C. • Haemaccel does not induce antibody formation. • It is used - when rapid plasma volume expansion is needed like burns in correcting hypovolaemia sometimes; in plasmapheresis as exchange fluid. • 500 ml of 5% albumin is infused at a rate of 2 ml per minute. • It is used as volume expander in hypovolaemia. It increases the blood sugar also. • It is also used as antithrombotic agent. Dextran is a plasminogen activator; inhibits erythrocyte aggregation and platelet adhesiveness. • It improves microcirculation and blood flow. • Dextran 40 is commonly used. • It is used as a rapid volume replacement in circulatory collapse like shock, burns and trauma. It is infused rapidly at a rate of 125 drops/minute. H2 blocker like cimetidine or ranitidine should be given along with haemaccel as it releases histamine. • It improves the plasma volume rapidly and remains like that for 5 hours. • It will not interfere with coagulation, blood grouping and cross matching. • It is used also in heart lung machine. • Haemaccel can be mixed with other IV fluids and drugs. • Haemaccel can be infused up to 2000 ml. • It is contraindicated in cardiac failure, anaemia. • It can cause allergic reactions, nausea, febrile reactions. • It causes electrolyte disturbances and hyponatraemia. • It causes acute renal failure by direct toxicity to glomerulus and tubules and by intraluminal hyperviscosity. • It should be used carefully in diabetic patients. • It can cause pulmonary and or cerebral oedema also due hyperosmolarity. • It can cause anaphylaxis (being a potent antigenic). • It can interfere with blood grouping and cross matching. • It prolongs the bleeding time and so may precipitate bleeding. Rapid histamine release and anaphylactoid reaction. Contd... Electrolyte and Nutrition 101 Hetastarch (hydroxyethyl starch) It is nonionic starch derivative, which is ethoxylated amylopectins which is a plasma volume expander. Pentastarch It is a subgroup of hetastarch with five hydroxyethyl groups with 50% esterification. It is a low molecular weight derivative; it is more effective plasma volume Contd... • It is a synthetic colloid available as 6% solution in 0.9% normal saline (30 gram hetastarch in 500 ml of isotonic saline). It is administered IV only using infusion pump; 20 ml / kg / hour; it is stored in room temperature. It is enzymatically degraded and causes rise in serum amylase level. • Total dose per day should be 1500 ml only. • It is used in hypovolaemia— shock, burns, trauma. • It is also used in leukapheresis. • It is nonantigenic; does not interfere with blood grouping. • It shows greater plasma volume expansion for longer period compared to 5% albumin. • Anaphylactoid reactions can occur. • Renal impairment should be observed. • It has no O2 carrying capacity; so should not allow haematocrit to fall below 30%. • Impairment of coagulation is possible. It is available as 3%, 6% and 10% in normal saline. • It is used in hypovolaemia. • It is useful in cardiac surgeries. expander. NUTriTioN Caloric values: We (now) devote more attention to the patient’s diet and habits, and more often send him away with good advice than with hastily-written prescriptions. x x Carbohydrate 4 kcal/g. x x Protein 4 kcal/g. x x Fat 9 kcal/g. —Robert Hall Babcock, 1901 Indications for Nutritional Support a. Preoperative nutritional depletion. b. Postoperative complications: Sepsis, ileus, fistula. c. Intestinal fistula: High type wherein output is more than 500 ml/ day. It may be duodenal, biliary, pancreatic, intestinal. d. Pancreatitis, malabsorption, ulcerative colitis, pyloric stenosis. e. Anorexia nervosa and intractable vomiting. f. Trauma—multiple fractures, fasciomaxillary injuries, head and neck injuries. g. Burns. h. Malignant disease. i. Renal and liver failure. j. Massive bowel resection causing short bowel syndrome. Assessment Principles of Nutrition x x Avoiding of malnutrition is the basic goal in nutrition therapy as malnutrition increases the morbidity and mortality of the disease process and prevents or delays the recovery. Malnutrition increases the chance of sepsis, prevents wound healing, increases the respira- tory complications, and decreases the efficacy and tolerance to radiotherapy or chemotherapy. x x Whenever possible enteral route of nutrition should be used ideally. If that is not possible then parenteral nutrition is used. x x Overfeeding should be avoided as it leads into hyperglycaemia, hepatic steatosis, raised BUN, and excess CO2 production. x x Timing and type of nutrition is also important. x x Nutrition therapy reduces protein wasting. x x Immunomodulators like glutamine, arginine and omega 3 fatty acids are also very useful. Glutamine is a nonessential amino acid synthesized in skeletal muscle. It is essential for cell proliferation during tissue repair. Glutamine helps GI mucosal cell prolifera- tion, maintains mucosal integrity, improves immune function and prevents translocation of bacteria. It is useful in inflammatory bowel disease, short gut syndrome, burns, major trauma, and sepsis. Glutamine is used commonly by enteral route even though IV preparations are now available (but it is very unstable in solutions). Caloric requirement: x x Neonatal 100 kcal/kg/day. x x Adult 40 kcal/kg/day. x x Adult with catabolism 60 kcal/kg/day. It is given as: x x Carbohydrates 50%. x x Fat 30–40%. x x Protein 10–15%. ™ ™ Body weight ™ ™ Mid-arm circumference ™ ™ Triceps skin fold thickness ™ ™ Serum albumin ™ ™ Lymphocyte count Nutritional requirements: Carbohydrates, fat, proteins, vitamins (includes fat-soluble vitamins also), minerals, trace elements. Methods of Feeding Enteral: a. Gastrointestinal tract is the best route to provide nutrition. b. Enteral feeding can be delivered by bolus, by gravity or using mechanical pump.   By mouth: Requires: – Common sense, – – Cleanliness, – – Compassion. – We will not know unless we begin. 102 SRB's Manual of Surgery   By nasogastric tube: Confirmation of the tube in the stomach is made by injecting 5 ml of air down the tube and listening through a stetho­ scope for its bubbling entry into the stomach. Feeding rate is 30–50 ml/hours. 5 hours night time gap is given to allow gastric pH to return to normal. Problems with tube feeding are: ™ Blockage ™ ™ Nausea and vomiting, aspiration ™ ™ Hyperosmolarity ™ ™ Diarrhoea ™ ™ Tube discomfort ™ ™ Cholestasis ™ c. By enterostomy:   Gastrostomy.   Jejunostomy. filter to process and store. Gallstone formation is prevented (unlike long-term TPN) by stimulating gall-bladder motility. x x It has got less serious complications. It is cost-effective. x x It supplies glutamine and short chained fatty acids to gut. Contraindications of Enteral Nutrition x x Intestinal obstruction, GI bleed, paralytic ileus, severe diarrhoea, high output fistula. x x Low cardiac output, haemodynamically unstable patient. x x If safe access to enteral feeding is not present. x x Anticipated complications if thought to be present should be avoided. gasTrosTomy It is done if feeding is required for more than one month. Indications ™ ™ Severe malnutrition ™ ™ Major surgeries ™ ™ Severe sepsis ™ ™ Trauma ™ ™ Head and neck surgeries Fig. 1.197: Nasogastric tube passed should be confirmed in place using stethoscope. Tube is used for feeding purpose. Types Based on duration of use: x x Temporary. x x Permanent. Based on lining: x x Mucus lined (permanent). x x Serosal lined (temporary). Based on technique: a. Stamm temporary gastrostomy: After opening the abdomen, anterior wall of the stomach is opened. Feeding tube (Malecot’s catheter) is placed in position. Two layers of purse string sutures are put around the tube. Wound is closed. Different preparations and formulas are available for enteral feeding. Soluble fibre containing diets along with nutrients are better to prevent diarrhoea. Complications of enteral feeding ™ Aspiration ™ ™ Wound infection and leak ™ ™ Diarrhoea due to rapid feeding or hyperosmolarity ™ ™ Hyperglycaemia ™ ™ Hypokalaemia ™ ™ Refeeding syndrome due to severe hypokalaemia and hypophos- ™ phataemia Advantages of Enteral Nutrition x x Enteral nutrition preserves mucosal protein, digestive enzymes, IgA secretion; prevents mucosal atrophy and bacterial translocation. x x It is more physiological as nutrients pass through liver, the first Fig. 1.198: Gastrostomy tube in place for enteral feeding. Electrolyte and Nutrition 103 A B Figs 1.199A and B: Percutaneous endoscopic gastrostomy (PEG). Guidewire passed through a trocar in the abdominal wall into the stomach is pulled out across the oesophagus and mouth under visualisation using gastroscope. Gastrostomy catheter (tube) is passed along the guidewire and pushed downwards across mouth and oesophagus to reach the stomach. It is further pushed along the abdominal wall through the trocar. Gastrostomy tube is pulled out through abdominal wall and fixed. Trocar is removed. Placement of tip of gastrostomy tube can be confirmed by doing gastroscope. b. Kader-Senn temporary gastrostomy. c. Percutaneous endoscopic gastrostomy (popular)—now becoming common method. d. Janeway’s mucus lined permanent gastrostomy by creating tunnel in stomach wall. Problems in gastrostomy ™ ™ Leak—gastric fistula ™ ™ Infection ™ ™ Aspiration and pneumonia ™ ™ Diarrhoea is common—30% ™ ™ Bloating, abdominal cramps ™ Displacement, blockage of the tube ™ Contraindications x x Previous gastric surgeries. x x Intestinal obstruction. x x Gastric outlet obstruction. JEJUNosTomy Jejunostomy for enteral nutrition is becoming more popular because of: x x Its comfort, x x Easy to do, x x Can be kept for long time, x x Lesser complication than gastrostomy. Indications are same as gastrostomy. Types a. Witzel jejunostomy: Site of placing jejunostomy is 30 cm from duodenojejunal junction. b. Needle jejunostomy using catheter of small gauge. The secret of happiness is to admire without desiring. 104 SRB's Manual of Surgery Fig. 1.200: Needle jejunostomy. TOTal ParENTEral NUTriTioN (TPN) All nutritional requirements are given only through intravenous route, not through gastrointestinal tract. It can be through a central catheter through the subclavian/internal jugular vein where the tip of venous catheter is at distal part of superior vena cava. It can also be a peripheral (Peripheral parenteral nutrition/ PPN) through a peripherally inserted central venous catheter (PICC) or through a formal peripheral venous line. Indications ™ Failure or contraindication for any enteral nutri­ tion for 7–10 days ™ ™ ™ High output abdominal fistulas, duodenal, biliary, pancreatic fistulas ™ Major abdominal surgeries of liver, pancreas, biliary, colonic ™ ™ Septicaemia ™ ™ Multiple trauma ™ ™ Short bowel syndrome ™ ™ Severe pancreatitis, bowel ischaemia, peritonitis, ileus ™ ™ Massive GI bleeding, unstable haemodynamically ™ ™ High risk of aspiration ™ ™ Hyperemesis gravidarum ™ ™ Multiorgan failure, head injury, severe burns ™ About 5% of hospital admissions require TPN. Technique x x Using a needle and guide wire a Subclavian vein catheter is passed just below the clavicle and fixed securely to the skin. x x TPN is given through central vein and not through a periph- eral vein. x x Peripherally inserted central catheter (PICC) is also com­ monly used (PPN). Goals, Factors and Assessment in TPN x x To decrease adverse effects of catabolism; to increase protein synthesis, to reduce protein breakdown, to prevent weight loss. x x To support ongoing metabolism. x x To improve immune function, cardiac and respiratory function. x x To maintain glycogen reserve in cardiac and respiratory muscles. x x To maintain acid, base and electrolyte metabolism. x x Age, premorbid state, muscle mass, weight, serum albumin should be assessed. x x Underlying disease, its severity, therapies for the disease, GI func- tion should be assessed. x x Fluid requirement is assessed by—1500 ml for 20 kg weight + 20 ml/kg for additional weight. x x Energy needed is calculated by calculating resting energy expendi- ture (REE).   By simple calculation: REE in kcal/day = 25 × weight in kg.   Harris Benedict equation: REE in men = 66 + (13.7 × weight in kg) + (5 × ht in cm) – (6.7 × age in years). In women = 655 + (9.6 × weight) + (1.8 × ht) – (4.7 × age). Activity/disease/ thermal factors are also added.   Indirect calorimetry: It is more accurate method done using special instrument. REE: = (3.9 × VO2) + (1.1 × VCO2) – 61. Components used in TPN ™ ™ Carbohydrates ™ ™ Fat and amino acids ™ ™ Vitamins and trace elements, electrolytes, minerals Components used in TPN/PPN Carbohydrates: Dextrose is less costly (1 gram dextrose 3.4 kcal); can be used in 50–70% concentration during PN. It supplies calories, stimulates insulin release and glucose oxidation, prevents muscle protein breakdown, has got nitrogen sparing ability. Problems of carbohydrate/dextrose are—low calorie value compared to fat, requires large fluid volume to infuse, hyperglycaemia, causes more CO2 production, because of high osmolality it causes thrombo- phlebitis in 10% or above concentration. Rate of administration of dextrose is 5 mg/kg/min. Fat: Fat gives high calorie (1 gram—9 kcal), essential fatty acids. It is given as emulsion containing long chain triglycerides. It contains soyabean/sunflower oil with egg yolk phospholipids (emulsifying factor), glycerin (isotonic). Fat has got low osmolality (260 mosm/L); it is available as 10%, 20%, 30% emulsions. Advantages of fat in PN are—high calorie, prevents hyperglycaemia, glucose and nitrogen sparing, less CO2 production, less insulin production; it prevents essential fatty acid deficiency (for this purpose 3 days a week dose is given), reduces thrombophlebitis. Problems of lipids in PN are— hypertriglyceridaemia, sepsis, fat embolism, fat overload, hepatic dysfunction, pancreatitis, delayed gastric emptying. Lipid emulsions are avoided in hyperlipidaemia, anaemia, acidosis, obesity. Lipid emulsion is a good culture media for bacteria and fungi; so care should be taken to prevent sepsis. Triglyceride level should be monitored weekly; if more than 400 mg%, infusion is discontinued. Mixture of long and medium chain fatty acids is better tolerated and efficient. Amino acids: They are source of proteins. Calorie value of amino acid is 4 kcal/gram. 6.25 gram protein has 1 gram nitrogen. In PN 20% of energy comes from amino acids; rest from dextrose and fat. Daily protein need is 0.8–1.5 gram/kg. Protein supplement should be less in patients with CRF and hepatic encephalopathy. Its need is more in burns, trauma, enteropathy, sepsis. Protein supplement should not exceed 1.7 gram/kg/day; if so will cause raised urea production. Uses of amino acids in PN—in protein anabolism; prevents scatabolism. Proper monitoring by doing BUN or ammonia level is essential during amino acid therapy. Electrolyte and Nutrition 105 Vitamins, electrolytes, trace elements and minerals: Electrolytes like sodium, potassium, magnesium, phosphate, calcium; fat-soluble vitamins like A, D, E, K; water-soluble vitamins; trace elements like chromium, copper, iodine, iron, manganese, selenium, zinc are all used in PN. Monitoring the patient ™ ™ By body weight, fluid balance, blood glucose, electrolytes, blood urea, LFT, serum calcium, magnesium, phosphate should be done at regular intervals. ™ ™ A weight gain more than one kg/day signifies fluid overload. Complications Technical a. Air embolism. b. Pneumothorax. c. Bleeding. d. Catheter displacement, sepsis, blockage. e. Infection, thrombosis. Biochemical a. Electrolyte imbalance: Hyponatraemia, hypokalaemia, hypophos- phataemia. b. Hyp erosmolarity. c. Hyperglycaemia—common. d. Dehydration. e. Altered immunological and reticuloendothelial function. f. Azotaemia. Others a. Dermatitis. b. Anaemia and increased capillary permeability. c. Cholestatic jaundice: It is common. d. Severe hepatic steatosis. e. Metabolic acidosis. f. Candida infection (candidiasis), staphylococcal infection (10–15%). rEFEEDing SyNDrome x x Refeeding syndrome is occurrence of severe fluid and electrolyte imbalance in severely malnourished individual while starting the proper feeding enteral or parenteral nutrition. It is more common in TPN. x x It causes hypomagnesaemia, hypocalcaemia and hypophospha- taemia leading into myocardial dysfunction, respiratory changes, altered liver functions, altered level of consciousness, convulsions and often death. x x Gradual feeding and correction of magnesium, phosphate and calcium and other electrolytes is important. x x Condition is common in chronic starvation, severe anorexia and alcoholic patients. OBEsiTY AND morBID OBEsiTY Obesity is weight more than 20% above the normal. Body mass index (BMI) is weight in kilogram divided by height in metres squared [wt in kg/(Ht in meters)2]. Morbid obesity is a condition wherein BMI is more than 40 kg/ m2. It is often also defined as weight 100 lbs or more; or 100% over ideal body weight. Weight more than double the expected weight to that age and height of the individual is also often called as morbid obesity. Body weight exceeding BMI 50 kg/m2 is called as superobesity. Causes of obesity x x Familial, hyperinsulinism, hyperadrenocorticism, hyogonadism. x x Abnormal eating behaviour: Hormones which control eating are—ghrelin from stomach; insulin from pancreas; leptin from fat; PYY 3–36 from colon. Hypothalamus is the center in CNS which controls eating. Contraindications ™ ™ Cardiac failure ™ ™ Blood dyscrasias ™ ™ Altered fat metabolism Anabolic steroid durabolin 25 mg IM weekly is given to improve nitrogen balance. Nutritional status BMI (kg/m2) • Underweight • <18.5 • Normal • 18.5–24.9 • Overweight (Preobesity)• 25.0–29.9 • Obesity • >30 – Class I – – 30.0–34.9 – – Class II (Moderate)– – – 35.0–39.9 – Class III (Severe / Morbid)– – – 40.0 • Superobesity• >50 • Super superobesity• >60 Home parenteral nutrition ™ ™ It is becoming popular ™ ™ It is commonly used in western countries ™ ™ It is indicated in short bowel syndrome or any other conditions wherein enteral feeding is not possible but patient can be sent home with provision for home parenteral nutrition ™ ™ Patient himself uses the TPN fluids as advised at home. He will be with TPN catheter ™ ™ Patient should attend TPN clinic weekly for follow-up or imme- diately whenever complications arise ™ ™ Patient will be comfortable psychologically and often can attend his job also Obesity is more common in young women. Child of a normal weight parents has 10% chance to become obese. If both parents are obese then child has got 80% chances to develop obesity. Problems with Morbid Obesity Obstructive sleep apnoea, degenerative joint disease, back pain, hypertension, GERD, gallstones, type II diabetes, hyperlipidaemia, arrhythmias, venous diseases, DVT, skin diseases, urine incontinence, infertility, ventral hernias, obesity hypoventilation syndrome, poly- cystic ovarian disease, hirsutism, gynaecomastia, steatohepatosis, malignancies—are common problems. All these conditions are called as comorbidities. The fool is never satisfied while the wise man finds wealth in contentment 106 SRB's Manual of Surgery Infertility is common in married morbid obese women due to improper ovulation, polycystic ovary disease. Urinary incontinence is common in morbid obese women (stress incontinence and detrusor instability). Pregnancy in morbid obese patient is considered as high- risk pregnancy. Gestational diabetes, hypertension, are common. It is better these women to undergo bariatric surgery prior to pregnancy which definitely reduces the complications during pregnancy. Such individual after bariatric surgery needs more iron and vitamin supple- ments. Evaluation of the patient—cardiac and respiratory assessment; lipid profile; blood glucose; renal and liver status assessment; anaesthesia risk assessment. Medical Management x x General: Diet, life style changes, exercise. x x Drugs: (1) Orlistat is a selective inhibitor of gastric and pancreatic lipases that reduces the absorption of lipids from intestine. (2) Sibutramine is a noradrenaline and 5 HT reuptake inhibitor which act as appetite suppressor. Surgical Treatment (Bariatric Surgery) Bariatric surgery causes long-term durable weight loss. Patient’s eating behaviour is reduced to slow ingestion of small boluses of food and or also reducing the absorptive surfaces. Types of Bariatric Surgery a. Restrictive wherein caloric intake is reduced. Purely gastric restrictive procedures are vertical banded gastroplasty (VBG) and laparoscopic adjustable gastric banding (LAGB). b. Malabsorptive wherein absorption of calories and nutrients from food is reduced. Biliopancreatic diversion (BPD) and biliopancre- atic diversion with duodenal switch (BPD-DS) are malabsorptive procedures. c. Combined wherein both methods are used. Roux-en-Y gastric bypass (RYGB) is both restrictive and malabsorptive types. Gastric bypass reduces GI polypeptide ghrelin level secreted from fundus of stomach and duodenum. Ghrelin acts on specific receptor in CNS—hypothalamus to initiate appetite. This stimulation is reduced to decrease appetite. In restrictive only procedure ghrelin level raises and so appetite stimulation is not controlled. Indications for Bariatric Surgery BMI more than 40 kg/m2 or BMI more than 35 kg/m2 with comorbidity is indication for bariatric surgery. American Association of Bariatric Surgery (ASBS) published indications and approved surgeries. Contraindications Patients who are unfit for general anaesthesia (cardiac/renal/respira- tory/hepatic causes) or who are unable to adjust post-operative life styles or psychiatric patients are contraindications for bariatric surgery. Preoperative Preparations and Evaluation x x Complete cardiac, respiratory/renal/hepatic evaluation. x x Lipid profile and blood glucose assessment. x x Obstructive sleep apnoea in obese patient should be assessed using polysomnography and be treated. x x Risk assessment for DVT should be done. x x If GERD symptoms are present gastroscopy should be done. x x USG abdomen to identify gallstones should be done; if gallstones present it is of usual practice to do cholecystectomy along with bariatric procedure. x x Nutritional evaluation and dietician advice for preoperative and postoperative diet management. x x Psychological screening is needed to all patients to counsel their postoperative care and diet. x x Separate theatre table is needed for morbid obese patient. Equip- ments should be long and flexible. In laparoscopic surgery, special ports and instruments are needed. DIFFERENT S UrgEriES Vertical Banded Gastroplasty (VBG); Mason (1982) It is a purely restrictive type with creation of a calibrated stoma in the lesser curvature which is reinforced by an encircled mesh with a proximal gastric pouch. After laparotomy Ewald’s stomach tube is passed per orally to place against lesser curve. A 2.5 cm circular window is created in the body of stomach near lesser curvature 8 cm below the angle of His. After this, four lines of linear vertical stapling are done from circular opening towards angle of His. This staple line ideally should be divided using another cutting linear stapler to reduce chances of dehiscence. This creates a 50 Complications of obesity Obesity and surgery Treatment for obesity • General: Difficulty in work, fatigue, depression, back pain, arthritis and gout • Cardiovascular: Hypertension, stroke, thrombophlebitis, pulmonary embolism • Pulmonary: Hypoventilation, poor respiratory effort • GIT: Hiatus hernia with reflux, changes in liver, pancreatitis, gallstones • Endocrine: Diabetes mellitus • Hernia and gallstones are more common in obese individual • Burst abdomen, incisional hernia are more common in obesity • Delay in recovering from anaesthesia • Infertility is more common • General: Dieting, exercise • Drugs: Orlistat, Sibutramine • Surgeries: – Restrictive – Š Vertical banded gastroplasty Š Š Laparoscopic adjustable gastric Š banding (LAGB) Š Jaw wiring Š – Malabsorptive – Š Biliopancreatic diversion (BPD) Š Š Biliopancreatic diversion with Š duodenal switch (BPD-DS) Š Jejunoileal bypass Š – Combined – – Roux-en-Y gastric bypass (RYGB) – open or laparoscopic Electrolyte and Nutrition 107 Fig. 1.201: Vertical banded gastroplasty (VBG). ml proximal gastric pouch. A 1.5 × 7 cm polypropylene mesh is placed around the lesser curve through circular opening and sutured to create a 5 cm collar stoma. It is not used at present; it is only of historical importance. VBG causes only medium term weight loss; its efficacy is less compared to other procedures. Complications of VBG are—stricture at stoma (20%), vomiting (30%), reflux (20%), staple line dehiscence (40%), conversion into other procedures. Mortality is 0.3%. VBG is technically easier to do; it has got very less chances of long-term metabolic and nutritional deficiencies. Laparoscopic Adjustable Gastric Banding (lagB) It is also a restrictive type (1992, Guy Bernard) to create a narrow stoma just below the OG junction. It is used in adolescents and elderly. It is contraindicated in hiatal and paraoesophageal hernias. It is done using laparoscopy. Under general anaesthesia, with patient in reverse Trendelenburg position six laparoscopic ports are placed. Using pars flaccida method, retrogastric tunnel is created; a silicone band is passed through the tunnel to encircle the cardia just below the OG junction; tail of the band is buckled and locked. Stoma diameter is determined by inserting a calibration tube. Stomach over the band is imbricated using interrupted sutures except the buckle area. Silicone tube end is brought out through the abdominal wall to connect access port. It is used for band volume adjustment by injecting or withdrawing the saline. Gastrograffin study is done on 1st postoperative day to assess band position and lumen patency. Patient is advised to have liquid diet for one month. Band adjustment is done under fluoroscopic guidance in 2 months. Adjustment is done to achieve weight loss at a rate of 2 kg/ week. Efficacy of LAGB is 55%. Complications of LAGB are—spleen/stomach injury; bleeding; band slippage (10%); band erosion (7.5%); tube related complications; vomiting; pouch dilatation; reflux. Conversion rate is 3%; mortality is less than 0.5%. Complication rates were higher and so procedure is not prac- ticed. Colon in these patients absorbs high level of oxalate causing nephrocalcinosis. Bypassed bowel promotes bacterial growth causing endotoxic-induced liver injury, cirrhosis, liver failure. Complications like protein, vtamin K, vtamin B12 deficiencies; gallstone formation; enteritis and diarrhoea; arthritis, osteoporosis are common. Roux-en-Y Gastric Bypass It is commonly done combined procedure. It can be done by open or laparoscopic method. Proximal stomach is dissected between 1st and 2nd branches of left gastric branches. Vagii nerves and nerves of Latarjet are retained carefully. Stomach is transected at this proximal site to create a proximal gastric pouch (15 ml if BMI is > 50; 30 ml if BMI is 40–50). It is usually carried out through linear stapler. Jejunum is transected 45 cm from ligament of Treitz. A side to side jejunojejunal anastomosis is done using stapler 75 cm distal to the distal cut end. Proximal Roux part of the distal jejunal cut part (75–150 cm, based on patient’s preoperative weight) is brought out through the transverse mesocolon towards the created proximal gastric pouch and gastrojejunostomy is done to this proximal gastric pouch. Mesenteric defect is closed. Stomal integrity is checked on table by air distension and methylene blue infusion. Gastrograffin study is done in 24 hours to assess pouch size, stomal patency and distal obstruction. Oral food is started in 24 hours and patient is discharged in 4 days. RYGB is more useful in weight loss compared to purely restrictive types. 5 years weight loss is 60–75%. It also prevents progression of noninsulin dependent diabetes mellitus, controls hypertension, sleep apnoea, hyperlipidaemia, asthma, arthritis, GERD. Complications are—Roux obstruction, anastomotic leak, acute distal gastric dilatation, stomal stenosis, marginal ulcer, dumping syndrome, internal hernias, vitamin B12 deficiency, iron deficiency anaemia. Distal gastric dilatation needs emergency intervention which is usually due to jejunojejunal obstruction. Jejunoileal Bypass It was the first malabsorptive procedure done for obesity. Now this technique is not done due to high incidences of complications. Proximal jejunum is divided and proximal cut end is anastomosed to distal ileum just proximal to ileocaecal valve to reduce the absorp- tive surface area of small bowel. Laparoscopic rygB (1994, Wittgrove, Clark, Trembly) Technique is similar to open RYGB. Anastomoses are done using endoscopic stapler. GJ between gastric pouch and Roux jejunum is done either using linear stapler through laparoscopic port after making a gastrotomy in the pouch which is later sutured after staple firing; or using circular stapler anastomosis is done wherein anvil is initially passed transorally often under endoscopic guidance across the pouch into the The lazy man is always occupied with his laziness. 108 SRB's Manual of Surgery Fig. 1.202: Laparoscopic adjustable gastric banding (LAGB). Fig. 1.203: Jejunoileal bypass procedure (JIB). Roux jejunum; or using hand sewing with absorbable sutures. Omentum is released from the colon and is covered over the GJ. Mesenteric defect and Patterson Brown defect are closed. A Bronlin antiobstructive stitch is placed between Roux and biliopancreatic limbs. Integrity of anastomosis is checked using insufflation of air, methylene blue. Complications are similar to open RYBG. Conversion rate is 9%. Advantages of LRYBG to open RYBG are—faster recovery, less post-operative pain, less wound related complications, less morbid one. Disadvantage of LRYBG is availability of facility, technical expertise, and steep learning curve. Now technique is modified to antegastric, antecolic one which has become popular (Gagner). Biliopancreatic Diversion (BPD) (Nicola Scopinaro, Italy) It is done in patients who had failed restrictive procedure or who are superobese. Distal subtotal gastrectomy is done with formation of proximal gastric pouch (of 400 ml in BMI 40–50; 200 ml in BMI >50). Ileum is transected 250 cm proximal to ileocaecal valve; distal ileal segment is brought up to anastomose into the proximal gastric pouch. Proximal biliopancreatic jejunoileal limb is anastomosed into distal ileal segment 50 cm proximal to ileocaecal valve as end to side stoma. Additionally cholecystectomy should be done. Modification of BPD with duodenal switch (BPD-DS) has become more popular. Here sleeve gastrectomy along the greater curvature is done to create gastric reservoir (200 ml) along lesser curve. Duodenum just distal to first part is divided using stapler; proximal cut end is sutured to proximal upward pulled end of the distal ileal segment of earlier transected ileum, 250 cm from ileocaecal valve. Biliopancreati- coduodenal with proximal jejunoileal segment is later stapled to distal ileum 50 cm proximal to ileocaecal valve. Duodenal switch reduces the rate of marginal ulcer and dumping syndrome. Results of BPD/BPD-DS are—excellent for weight reduction compared to restrictive procedures. But they need lifelong supplement of vitamins, fat-soluble vitamins, calcium, and iron. Technically BPD is easier to do when compared to BPD-DS. Complications of BPD/BPD-DS are—anemia (30%); protein deficiency (20%); dumping syndrome; marginal ulcer (in BPD 10%; in BPD-DS it is 1%); osteoporosis; night blindness; biliopancreatic Fig. 1.204: Roux-en-Y gastric bypass procedure (RYBG). Fig. 1.205: Biliopancreatic diversion procedure (BPD). Electrolyte and Nutrition 109 cm from duodenojejunal flexure. Isolated 170 cm ileal segment is interposed 50 cm distal to DJ junction with end-to-end anastomosis on both ends. Type 2: After doing sleeve gastrectomy, gastroduodenal junction is transected; cut proximal end of duodenum is closed. 170 cm ileal segment with mesentry is isolated and interposed between cut end of stomach and side of jejunum 50 cm distal to DJ flexure. Fig. 1.206: Biliopancreatic diversion with duodenal switch procedure (BPD-DS). limb obstruction; staple line leak; staple line bleed; DVT; subphrenic abscess. Vitamin B12 deficiency is specific. Ileal Interposition with Sleeve Gastrectomy It is done mainly in type II diabetes. Often they are associated with obesity, dyslipidaemia, hypertension, nephropathy and neuropathy. Two types of ileal interposition with sleeve gastrectomy are done. Type 1: Sleeve gastrectomy is done. 170 cm of ileum with mesentery is isolated 30 cm from ileocaecal junction. Jejunum is transected 50 Cholecystolithiasis After Bariatric Surgery Gallstone formation is common after bariatric surgery (50%). It is due to rapid weight loss. If gallstones are present at the time of bari- atric surgery it is essential to do laparoscopic cholecystectomy during bariatric procedure. It is controversial about doing prophylactic cholecystectomy during bariatric surgery even though it is prac- ticed in many places. Advantages are—it prevents future gallstone formation at the time of bariatric surgery (loss of access); it prevents difficulties in approaching CBD in case needed endoscopically due to surgery. Disadvantage is cholecystectomy adds additional 1 hour time for bariatric surgery increasing the risk of immediate complications. Patients who are not having gallstones at the time of bariatric surgery, should receive ursodeoxycholic acid 300 mg twice daily for 6-12 months of post-bariatric surgery period. Often stomach is anchored to abdominal wall as access part to biliary system for future need. Note: Many of these patients after bariatric surgery require plastic surgery for abdominal contour (panniculectomy, abdominoplasty) after weight reduction due to bariatric surgery.