The document discusses postoperative fluid and electrolyte management. It covers enhanced recovery after surgery (ERAS) protocols, preoperative and postoperative diets, fluid compartments and electrolytes in the body, perioperative fluid management, monitoring of fluid balance and electrolytes, and management of common abnormalities like hyponatremia. It also provides guidance on fluid management for patients with medical conditions like diabetes and thyroid disorders in the postoperative period.

1. POST-OPERATIVE FLUID
AND ELECTROLYTE
MANAGEMENT
By Dr Ayman Taslima
MS Obs & Gynae
Patna medical college

2. • The successful outcome of surgery is based on thorough evaluation,
careful preoperative preparation and attentive postoperative care.
• Traditionally preoperative management has included nil by mouth after
midnight, liberal intraoperative fluids and dependence on opioid pain
medications for postoperative pain.
• Perioperative stress directly influences the postoperative morbidity.
• Stress increases immunosuppression, hypoxia, insulin resistance and
catabolism.
• So, to reduce postoperative morbidity, ENHANCED RECOVERY
AFTER SURGERY (ERAS protocols) have been formulated.

3. ENHANCED RECOVERY AFTER SURGERY
• ERAS protocols are comprehensive and address elements from patient’s
initial arrival in the office with her chief complains until she leaves the
hospital following surgery.
• 1) Preoperatively it includes- preoperative counselling, carbohydrate
loading, the use of liberal antiemetics and avoidance of prolonged fasting.
• 2) Intraoperatively, there is focus on normothermia, balanced fluids,
avoidance of drains, a minimally invasive approach, multimodal pain
medications, including regional anesthesia when able.
• 3) Postoperatively, the aims include early mobilization and feeding,
prompt discontinuation of intravenous fluids, multimodal pain
medications, timely discontinuation of urinary catheters, and regional
anesthesia.

4. PERIOPERATIVE DIET
• Fasting increases insulin resistance which increases perioperative
morbidity.
• The American Society of Anesthesiology (2017) recommends “eating ad lib
until 6 hours preoperatively followed by consumption of clear liquids
until 2 hours preoperatively”.
• It also includes preoperative carbohydrate loading like drinks containing
12.5% maltodextrin given 2 to 3 hours preoperatively has been shown to
improve insulin resistance and decrease hospital stay.
• Postoperatively, IV fluids are discontinued as soon as possible or at the
latest, on postoperative day 1.
• ERAS protocols recommend against bowel preparation.

5. BODY FLUID
• The total body water is distributed primarily
between 2 compartments, namely, extracellular fluid
(ECF) and intracellular fluid (ICF) compartments.
• ECF is present outside cells: Makes up about ⅓ of
total body water. It includes:
1)Intravascular fluid (¼ of ECF): primary component
of plasma
2)Interstitial fluid (¾ of ECF): lies outside blood
vessels
• ICF is present inside cells:
• Makes up about ⅔ of total body water
• Principal component of the cytoplasm of cells

6. ELECTROLYTES COMPOSITION
Sodium is major
extracellular cation
while potassium is
major intracellular
cation.
Chloride is more of a
extracellular anion.
Osmolarity of both
ECF and ICF is 281
mmol/L.

7. PERIOPERATIVE FLUID MANAGEMENT
• Plasma tonicity reflects the fluid status of body. Alteration in plasma tonicity
induces adjustments in circulating antidiuretic hormone (ADH) levels, which
ultimately regulate the amount of water retained in the distal tubules of kidney.
• In preoperative and early postoperative periods, it is usually necessary to replace
sodium and potassium because chloride is the usual anion present in commercially
available fluids and is automatically replaced.
• The daily requirement can be met by any combination of intravenous fluids.
• For example, 2 L of DNS (5% dextrose with 0.45 normal saline) containing 7mEq of
NaCl each, supplemented with 20 mEq of potassium chloride, followed by 1 L of
D5W (5% dextrose) with 20 mEq of potassium chloride, would suffice.
• The choice of solutions for replacement depend of type of fluid lost.

8. • Catabolism of protein and fat occurs in patient who are taking nothing by mouth,
which cause weight loss of approx. 300mg per day. Any weight loss beyond 300mg
per day, represents fluid loss.
• Patients with high fever can have increased pulmonary and skin loss of free water
sometimes even up to 3 L. This should be replaced with free water in form of D5W.
• Patients with acute blood loss need replacement with appropriate isotonic fluid or
blood or both.
• Plasma volume expanders like albumin, dextran, hetastarch solution contain large
molecular weight particles which are slow to exit intravascular space. One-half of
these particles remain in intravascular space after 24 hours. But their possible side
effects include, severe anaphylactic reaction and impaired renal function.
• Simple replacement with 0.9 normal saline or ringer lactate is sufficient and
economical in most cases. One-third of the volume of RL or NS typically remains
intravascular after 24 hours.

10. RINGER LACTATE
• It is the most physiological solution.
• Composition similar to that of extracellular fluid.
• Also known as Hartmann’s solution.
• Has an osmolarity of 273 mmol/L and a pH of 6.5.
• 1 L of ringer lactate contains- sodium - 131 mmol/L
• chloride – 111
mmol/L
• lactate – 29
mmol/L
• potassium – 5
mmol/L
• calcium – 2
mmol/L

11. NORMAL SALINE
• Contains 0.9% sodium chloride.
• Sodium – 154 mmol/L , chloride – 154
mmol/L.
• Osmolarity is 308 mmol/L.
• pH ranges from 4.5 to 7.
• It is isotonic to plasma.
• HALF NORMAL SALINE - contains 0.45%
of sodium chloride, and is thus hypotonic.

12. 5% DEXTROSE DNS
• Contains 5 gm glucose per 100 ml.
• Hypertonic to plasma.
• Osmolarity 250mOsmol/L.
• Provides 40 kcal/100ml.
• Good for postoperative replacement.
• Used to correct hypoglycemia.
• Contains 5 gm glucose per 100ml along
with 0.9% sodium chloride.
• Replenishes both calories and
electrolytes.
• Ideal for post operative period.
• Hyperosmolar to plasma.

14. POSTOPERATIVE FLUID MANAGEMENT
• The stress of surgery induces an inappropriately high level of circulating ADH.
Sustained episodes of hypotension increases the circulating levels of aldosterone. ADH
and aldosterone make postoperative patients prone to sodium and water retention.
• The total body fluid postoperative volume may be altered significantly. 1 ml of free
water is released for each gram of fat catabolized. Fluid retention is enhanced by third
spacing or sequestration in surgical field. The development of ileus may result in
additional 1 to 3 L of fluid per day being sequestered in the bowel lumen, bowel wall,
and peritoneal cavity.
• In contrast to sodium retention, kidneys continue to excrete a minimum of 30 – 60
mEq/L of potassium daily, irrespective of serum potassium level. Catabolism during 1st
postoperative day release sufficient potassium to meet daily requirement.
• Beyond the 1st postoperative day, potassium supplementation is necessary.

15. MONITORING
• Hemodynamic parameters, daily weight, urine output, serum hematocrit,
and serum electrolytes will yield the necessary information to make correct
adjustments in crystalloids replacements.
• After 1st few postoperative days, third space fluid begins to return to the
intravascular space and ADH and aldosterone levels revert to normal. The
excess fluid is mobilized and excreted through kidneys. Exogenous fluid
requirement decreases.
• Patients with inadequate cardiovascular or renal reserve are prone to fluid
overload during this time of third space reabsorption especially if IV fluids
are not appropriately reduced. Simple fluid restriction will correct the
abnormality. When necessary, diuretics can be given to increase urinary
excretion.

16. STARVATION AND ENERGY REQUIREMENT
• Starvation of more than 12 hours, leads to reduction in insulin levels
and increase in glucagon levels. This causes increased production of
glucose from protein catabolism, hepatic glycogenolysis, and lipolysis.
• Further there is reduction in resting energy expenditure from
approximately 25-30 kcal/kg/day to 15-20 kcal/kg/day.
• So the total energy requirement of a stable patient after surgery is
approximately 20-30 kcal/kg/day.
• This requirement can be met by using dextrose 5% or dextrose normal
saline.
• 1 litre of 5 % dextrose provides 400 kcal.

17. ASSESSMENT OF FLUID AND ELECTROLYTE
ABNORMALITIES
• After detailed history taking, assessment of hemodynamic, clinical, and
urinary parameters helps determine the overall level of hydration.
• A patient with good skin turgor, moist mucosa, stable vital signs and
good urinary output is well hydrated.
• While, patient with orthostasis, sunken eyes, parched mouth, and
decreased skin turgor has extracellular volume contraction.
• In case of pre-existing abnormalities, laboratory workup includes blood
hematocrit, serum chemistry, glucose, BUN, creatinine, urine osmolarity
and urinary electrolyte levels.
• Serum osmolarity = 2(Na) + glucose (mg/dL)/18 + BUN (mg/dL)/2.8

18. • Normal serum osmolarity is 290 to 300 mOsm.
• The BUN : creatinine ratio is typically 10:1 but it rises to greater than
20:1 under conditions of extracellular fluid contraction.
• Under conditions of extracellular fluid deficit, urine osmolarity will
typically be high (>400 mOsm), whereas urine sodium concentration
will be low (<15 mEq/L) indicative of an attempt by kidney to conserve
sodium.
• Under conditions of extracellular fluid excess or in cases of renal
disease, in which the kidney has impaired ability to retain sodium and
water, urine osmolarity will be low and urinary sodium will be
high(>30 mEq/L).

19. HYPERNATREMIA
• Normal serum sodium level is 135 to 145 mEq/dL.
• Uncommon condition but life threatening if severe (>160 mEq/L).
• Extracellular fluid deficit results in hyperosmolar state.
• Features include disorientation, seizures, intracranial bleeding and death.
• Cause – excessive extrarenal water loss like high fever, central or
nephrogenic diabetes insipidus, or iatrogenic salt loading.
• Treatment is replacement with free water either by oral route of
intravenously with D5W.
• Correction should be slow, not faster than 10 mEq per day unless the
patient is symptomatic from acute severe hypernatremia.

20. HYPONATREMIA
• Because sodium is major extracellular cation, shifts in serum sodium levels are usually
inversely correlated with hydration status of the extracellular fluid compartment.
• Symptoms occur inly when level falls below 125meq/L. severity of symptoms correlate more to
rate of change rather than absolute level.
• Symptoms include nausea, vomiting, lethargy and lately seizures. Causes could be
• 1) Inappropriate ADH secretion due to head trauma or cerebral /pulmonary tumors.
• 2) Inappropriate correction of body salt losses like in case of diarrhea or vomiting with water
alone or hypotonic solutions.
• 3) Renal or cardiac failures with resultant fluid retention.
• Management – simple water restriction suffices when cause has been corrected.
• Replacement with isotonic fluid and potassium usually corrects the abnormality.
• Rarely, 3%NaCl is required for rapid correction.

21. HYPOKALEMIA
• Normal potassium level is 3.5 to 4.5 mEq/L.
• Causes include –
• 1) Significant gastrointestinal loss due to prolonged vomiting, diarrhea, nasogastric
suction, or intestinal fistula.
• 2) Marked urinary potassium loss secondary to renal tubular disorders or prolonged
diuretic use.
• Symptoms- neuromuscular disturbances ranging from muscle weakness to flaccid
paralysis, hypotension, bradycardia, arrythmia or enhancement of digitalis toxicity.
• Symptoms occur only when potassium falls below 3mEq/L.
• Treatment – oral replacement preferred over intravenous replacement.
• Intravenous replacement should not exceed 10 mEq per hour.

22. HYPERKALEMIA
• Infrequent in postoperative patients.
• Usually associated with renal impairment, adrenal insufficiency, or potassium
sparing diuretics.
• Marked hyperkalemia (>7mEq/L) results in bradycardia, ventricular fibrillation
and cardiac arrest. ECG is done to detect cardiac abnormalities.
• Treatment – calcium gluconate 10 ml of 10% solution intravenously reverses
effects on heart.
• One ampoule of sodium bicarbonate and D5W with or without insulin, causes
rapid shift of insulin into cells.
• For long term correction, cation exchange raisins can be used orally .
• Rare situations require hemodialysis.

23. ALKALOSIS
• The most common acid-base disorder encountered in postoperative period
is alkalosis. Mostly not clinically significant and resolves spontaneously.
• Respiratory alkalosis occurs due to hyperventilation caused by CNS
excitation.
• Metabolic alkalosis occurs due to posttraumatic transient
hyperaldosteronism, nasogastric suction, infusion of bicarbonate during
blood transfusion and use of diuretics.
• pH > 7.55 can result in serious cardiac arrythmias or seizures.
• Management includes removal of inciting factors and correction of
extracellular fluid deficit and potassium deficit.

24. ACIDOSIS
• Respiratory acidosis results from CO2
retention due to hypoventilation.
• Metabolic acidosis is less common in
postoperative period, but can be serious
due to cardiovascular side effects.
• Proper workup includes measurement of
anion gap, which is normally 10 to 14
mEq/L.
• Anion gap = (Na + K) – (Cl + HCO3)
• With metabolic acidosis, the anion gap
can be increased or normal.

25. METABOLIC ACIDOSIS
• An increase in circulating acids will consume and replace bicarbonate ion,
increasing the anion gap.
• Postoperatively, conditions of poor tissue will increase circulating lactic
acid, severe diabetes or starvation will increase sulfates and phosphates.
• Metabolic acidosis with normal anion gap is usually the result of excess
chloride and decreased bicarbonate that can be seen in patients who
underwent saline loading, those with severe diarrhea or tubular acidosis.
• Treatment – oxygen therapy aggressive treatment of systemic infection
• Correction of ketoacidosis with insulin or correction of lactic acidosis.
• Bicarbonate can be supplemented when pH is < 7.2 or severe cardiac
complications are present.

26. POSTOPERATIVE
MANAGEMENT IN VARIOUS
PREEXISTING MEDICAL
DISORDERS

27. DIABETES MELLITUS
• Patients with diabetes mellitus have elevated risks of coronary artery disease and experience
exaggerated hyperglycemia perioperatively.
• Perioperative hyperglycemia (>250 mg/dL) is associated with increased susceptibility to infection and
poor wound healing.
• The American Diabetes Association endorses a perioperative glucose target range of 80 - 180 mg/dL.
• Patients on dietary control or oral medication, are treated with sliding scale regular insulin when
they are not taking oral food.
• Insulin dependent type 1 DM patients are more prone to ketoacidosis when they are not eating.
• Approximately one-third to half of patient’s usual daily dose of intermediate acting insulin is given
subcutaneously the morning before surgery. Short acting insulin must be avoided without oral
intake.
• An infusion of 5% dextrose should be given while fasting .
• Regular insulin can be administered during surgery as needed.

28. POSTOPERATIVE MANAGEMENT IN
DIABETES
• Postoperative monitoring is done to avoid hypoglycemia or hyperglycemia.
• During intravenous insulin regimen, blood sugar should be measured every
1 or 2 hourly.
• If sliding scale is used, the blood sugar should be measured and documented
every 6 hourly until the patient is eating and stable on preoperative
regimen.
• Serum glucose level should be below 140 mg/dL when fasting and below 180
mg/dL when random samples are taken.
• For type 2 diabetics, oral hypoglycemic agents can be started when the
patient resumes eating.

29. THYROID DISORDERS
• Ideally, a euthyroid state should be maintained 3 months before elective.
• Hyperthyroidism – when time does not permit establishment of a euthyroid
state, oral administration of propylthiouracil and a beta blocker can be
implemented for 2 weeks before surgery. Thyroid storm is the dreaded
complication, which can be managed beta blockers, steroids, thioamides and
iodine.
• Hypothyroidism- it decreases cardiac output by 30 to 50% as a result of
decreasing stroke volume and heart rate. Hyponatremia is also associated with
hypothyroidism. In elective surgery, surgery should be postponed until
replacement therapy is initiated. In emergency surgery, intravenous T3 or T4
may be given along with corticosteroids to avoid consequences of unrecognized
adrenal insufficiency.

30. CARDIOVASCULAR DISEASES
• Patients with heart disease tolerate anemia poorly.
• Serum sodium and potassium are particularly important in patients taking diuretics
and digitalis.
• Nearly two-third of postoperative myocardial infarction occurs during first 3 days.
This can be prevented by maximizing delivery of oxygen to the myometrium and
decreasing myometrial oxygen utilization. Anaemia should be corrected.
• Patients with coronary artery disease may benefit from beta blockers .
• Postoperative congestive heart failure frequently results from excessive
administration of intravenous fluids and blood products.
• Patients with mitral stenosis should be carefully monitored for pulmonary edema.
• Aortic stenosis patients are more prone to arrythmias.

31. HYPERTENSION
• Controlled essential hypertension have no increased risk of perioperative cardiac
morbidity or mortality.
• Patients with diastolic pressure more than 110 mmHg or systolic pressure more
than 180 mmHg should receive medication o control hypertension before surgery.
• Postoperative hypertension is treated parenterally because gastrointestinal
absorption may be diminished and transdermal absorption can be erratic in patients
who are cold or rewarming.

32. INVASIVE HEMODYNAMIC MONITORING
• It is integral to perioperative management of patients with
cardiovascular or pulmonary disease.
• It measures central venous pressure, left atrial pressure and
pulmonary capillary wedge pressure using pulmonary artery
catheterization.
• Not recommended to be used in non cardiac patients.