Fluid and electrolytes management in post op patients

sonal dixit , mbbs , ms obg

After surgery modification in normal physiology of fluid and electrolytes balance.
- ACUTE STRESS leads to increased sympathetic stimuli- tachycardia, vasoconstriction & stress.
Increased ACTH stimulate adrenal gland which secretes large amount of hydrocortisone to fight acute stress and aldosterone which leads to Na retension and urinary loss of K.

1. Fluid and Electrolytes Management in Post op patients Under guidance of Dr.(Prof) Nootan.C . Presented by Dr.Sonal Dixit

2. Why fluid therapy in surgical pt needs special consideration ? After surgery modification in normal physiology of fluid and electrolytes balance. - ACUTE STRESS leads to increased sympathetic stimuli- tachycardia, vasoconstriction & stress . Increased ACTH stimulate adrenal gland which secretes large amount of hydrocortisone to fight acute stress and aldosterone which leads to Na retension and urinary loss of K.

3. Increased ADH secretion causes water retension , reduction in U.O to as low as 500 ml on 1 st post op day. NBM status leads to hypovolemia prior to surgery, pt becomes hypotensive during surgery & anaesthesia . Fluid loss Surgical stress or direct damage of kidney,brain ,lung , skin or GI tract.

4. Goal of fluid therapy Aim to maintain B.P >100/70 mm of Hg Pulse rate of less than 120 bpm Hourly U.O between 30 and 50 ml Normal temperature, warm skin , normal respiration and sensorium .

5. When and how long to five post-op iv fluid ? Minor or major surgery? Short operative procedure ( no handling of intestine or viscera ) – maintenance i.v fluid to correct deficit due to NBM state. After 4-5 hours oral fluid is restarted & iv fluid is not needed. Major surgeries ( handling of intestinal viscera ) – requires post op iv fluid for few days.After ensuring normal movement of intestine oral fluid intake is restarted. Major surgery ( handling of intestinal viscera not done ) Most of OBG surgeries – I.V fluid is required for only 24 to 48 hrs.

6. Which factors to be considered before writing post op iv fluid ? Age , weight , vital data, hydration status and U.O. Nature of surgery, blood loss , nature and vol of fluid and blood replaced intraoperatively . Drain output , fluid lost at operative site. Renal status,associated illness ( HT,DM) and associated electrolytes and acid base disorders, if any. Insensible loss due to atmospheric temp,pyrexia,hyperventilation etc.

7. Routine Post Op Fluid for 1 st 3 days? 1 st 24 hrs of surgery- 2 lits D-5 or 1.5 lits D-5 + 500 ml isotonic saline. 2 ND post Op day- 2 lit 5% dextrose+ 1 lit of 0.9% saline. 3 rd post op day – Similar fluid + 40-60 mEq k per day. Guidelines which may require modification depending upon clinical situation.

8. Why maintenance I.V fluid on the 1 st post op day has less salt and its total volume is lesser? Increased ADH and aldosterone secretion –salt and fluid retention by the kidney . So as to avoid overloading of either salt or water , i.v fluid with lesser or even no sodium and in lesser volume than routine maintenance need of normal individual is prescribed.

9. When on 1 st post op day ,saline containing fluid is preferred? Elderly patients with salt losing nephropathy. Head injury or neurosurgical pts. Patients on diuretics and mannitol . To replace nasogastric aspiration and drain output. In most of the major surgery, saline is given to replace third space losses.

10. K is avoided in I.V fluids for 1 st 2 post operative day? Pt may have oliguria or azotemia . Post op trauma release K from intracellular to extracellular compartment- hyperkalemia . Intra or post op transfusion of stored blood Post operative metabolic acidosis shifts intracellular K extracellularly .

11. How to infuse IV fluid postoperatively ? Maintenance fluid should be given at a steady rate over an 18 to 24 hrs period. If given over a short period ,renal excretion of excess salt and water may occur. But as the normal losses continues over 24 hrs, body will be deprived of their fluid need during the remaining period.

12. Volume Excess Blood excess – pulmonary congestion. Saline excess- weight gain, periorbital puffiness, hoarseness or dysnoea on exertion. Hypotonic fluid excess ( 5% dextrose) – hyponatremia ( mental confusion, drowsiness or rarely coma or convulsions).

13. Fluid volume deficit Decreased U.O < 30 ml/hr Postural hypotension Tachycardia Diminished skin turgor Decreased capillary refill time Inc BUN out of proportion to creatinine TREATMENT Depends on the type of fluid lost , can be done with isotonic solutions –NS or LR.

14. Hyponatremia Excess ADH- retension of water In excess of sodium. Excess 5% dextrose Water administration consistently which exceeds water loss. Nausea without vomiting, drowsy, weak, confused or gets convulsion. TREATMENT Avoid using hypotonic solution . Avoid excessive use of electrolyte free solutions during the first 2-4 post op days. Serum Na should be kept between 130-135 mEq/ml

15. Hypernatremia Uncommon Excess isotonic saline. Diabetes insipidus Excess pure water loss in severe hyperglycemia due to osmotic diuresis . Treatment 0.45% NaCl – half strength saline

16. Hypokalemia Most common Lost through urine or GI. Post op infusion of mannitol or diuretics. Prolonged administration of potassium free i.v fluids. Extreme weakness , muscular hypotonia , paralytic ileus . Pts on digitalis therapy are more prone to develop cardiac arrythmias due to hypokalemia . Treatment Daily supplement 60 -100 mEq QD. Remember – hyperkalemia is more dangerous than hypokalemia .

17. Hyperkalemia Uncommon Cardiovascular symptoms- bradyarrhythmias , hypotension , diastolic cardiac arrest. ECG changes – wide QRS complex, peaked T waves. Treatment Inj cal gluconate , inj sod bicarbonate, glucose and insulin , kayexalate ( orally or by retension enema ).

18. Fluid management in Hypertension Remember that fluid overload can easily lead to pulmonary edema and cardiac failure in hypertensive patient, so ensure that fluid should be administered over strict 24 hrs and not faster. Sodium containing fluids will cause water retension and will increase the B.P eventually. Strict B.P monitoring should be done on 1 st post op day. Lasix will drop the b.p , increase the urine output but can cause disturbance in electrolyte levels.

19. Fluid management in Diabetes In diabetic post op patients there are high chances of development of diabetic ketoacidosis. Avoid using dextrose on 1 st post op day as already due to excess glucocorticoids the level of glucose is on the higher side. With DNS insulin should be added i.e neutralizing drip should be prepared. 10 units of human actrapid in 1 lit of DNS is a good option . RBS charting should be done 2 hrly of 1 st day , 4 hrly on 2 nd – come back to subcutaneous insulin or oral hypogycemic drugs once the patient starts on oral.

20. What is S liding S cale? RBS hourly. 150 to 200 – 4 units 201 to 250 – 6 units 251 to 300 – 8 units And so on … I.U of human insulin or human actrapid .

21. Blood transfusion Life saving

22. Advantage Most physiological way to replace blood loss. Corrects hypotension secondary to blood loss. Adequate tissue oxygen. Effective than crystalloids and cheaper than colloids to correct hypotension.

23. How to estimate intra op blood loss? Weigh sponges before and after use- diff in grams is eqivalent to ml of blood absorbed. + . Blood in suction bottle * 1½ = approx blood loss.

24. How to decide need for B.T? Pre op hemoglobin or hematocrit – Oxygen carrying capacity is unaffected till Hb is as low as 8 gm/dl & hematocrit is 25%. Percentage of blood loss T otal blood vol in adult female is 65 ml/kg. Loss less than 10% is insignificant. 10%-20%- clinical decision >20% - 100 % B.T

25. Eg - 500ml loss in 65 kg female ( total blood vol in ml = 65* 65 = 3575 ml ) , the loss less than 10% of total blood volume, which is not significant loss and does not require B.T. But same 500 ml loss in 20 kg female is 30% of total vol - significant and require B.T.

26. Other factors Vital data – emergency surgery in hypotensive pt needs B.T. Hydration status Old people Pts with IHD

27. How to estimate new Hb after intra op blood loss? Step 1 . Convert vol of blood loss into % % reduction of Hb = 1.25 * vol of blood loss / weight Step 2 . Convert % into reduction in gm /dl = preop Hb * % of reduction / 100 Step 3 . Hb status after blood loss = pre op hb in gm /dl – reduction in Hb gm /dl

28. Example – A 50 kg women with 14gm/dl loses 800 ml . New hb status? % reduction of Hb = 1.25 * 800/50 = 20% Reduction in gm /dl = 20 * 14/100 = 2.8 gm /dl Hb status after blood loss = 14-2.8 =11.2 gm /dl.

29. When not to give B.T? Blood loss less than 500 ml in adult with normal preop Hb . Loss of 10% of estimated blood vol is well tolerated , such losses are usually replaced with crystalloids like RL or 0.9% saline. As a rule blood loss needs to be replaced with 3 times vol of crystalloids.

30. When to give B.T? Blood loss > 20% of blood volume. Replacement of blood loss between 10% and 20% is a matter of clinical discretion. If Hb status after loss is expected to be less than 10gm/dl ,B.T is given. 500ml to 1000ml – single unit of blood is req. B.T is mandatory if Hb falls below 8gm/dl after blood loss.

31. What is MABL? Maximum allowable blood loss- amount of blood loss, which does not require B.T. = preop pt’s hematocrit-25 * estimated blood volume / preop pt’s hematocrit. Lowest acceptable hematocrit value is 25%.

32. Thank you Treat the patient as a whole, “Half a sheep is mutton.”