Fluid & Electrolytes Management of the Surgical Patient

Presenter: Ahmad Nabil B. Md Rosli

Supervisor: Dr Aziah

Total Body WaterTotal Body Waterbody wt%body wt% Total bodyTotal body

water%water%

totaltotal 6060 100100

intracellularintracellular 4040 6767

extracellularextracellular 2020 3333

intravasintravas 55 88

interstitialinterstitial 1515 2525

Composition of Fluids CompartmentComposition of Fluids Compartment

plasmaplasma interstitialinterstitial intracellularintracellular

CationsCationsNaNa 140140 146146 1212KK 44 44 150150CaCa 55 33 1010MgMg 22 11 77

AnionsAnionsClCl 103103 104104 33HCOHCO 2424 2727 1010SO4SO4 11 11 --HPO4HPO4 22 22 116116ProteinProtein 1616 55 4040

Normal Water ExchangeNormal Water Exchange

Average fluid lost (ml)Average fluid lost (ml)

SensibleSensibleurineurine 10001000intestinalintestinal 250 250

InsensibleInsensiblelungs/skinlungs/skin 600 600

Fluid and Electrolyte TherapyFluid and Electrolyte Therapy

Surgical patients needSurgical patients need 1.1. Maintenance volume requirementsMaintenance volume requirements2.2. On going lossesOn going losses3.3. Volume excess/deficitsVolume excess/deficits4.4. Maintenance electrolyte requirementsMaintenance electrolyte requirements5.5. Electrolyte excess/deficitsElectrolyte excess/deficits

1. Maintanence

This includes:insensible, urinary, stool lossesThis includes:insensible, urinary, stool losses

Example: 70 Kg Man NeedsExample: 70 Kg Man Needs

11stst 10kg x 100mls = 1000mls 10kg x 100mls = 1000mls

22ndnd 10kg x 50mls = 500mls 10kg x 50mls = 500mls

Next 50kg x 20mls = 1000mlsNext 50kg x 20mls = 1000mls

TOTAL TOTAL 2500 mls /d 2500 mls /d

2. On Going Losses2. On Going Losses

• NG NG

• drainsdrains

• fistulae fistulae

• third space lossesthird space losses

Concentration is similar to plasmaConcentration is similar to plasma

Replace with isotonic fluidsReplace with isotonic fluids

3. Disturbance in Fluid Balance (deficit)

• GI lost - nasogastric suction,vomiting, diarrhea, or fistula

• Skin lost - soft-tissue injuries, burns

• 3rd space lost - peritonitis, obstruction, or prolonged surgery

• Iatrogenic

• Renal dysfunction

• Congestive cardiac failure

• Cirrhosis

3. Disturbance in Fluid Balance (excess)

4. Maintenance Electrolyte 4. Maintenance Electrolyte RequirementsRequirements

Na 1-2mEq/Kg/d Na 1-2mEq/Kg/d

K 0.5 - 1 mEq/Kg/dK 0.5 - 1 mEq/Kg/d

Usually no K given until after urine output is adequate and U/E done.Usually no K given until after urine output is adequate and U/E done.

Always give K with care, in an infusion slowly - never bolusAlways give K with care, in an infusion slowly - never bolus

Ca, PO4, Mg not required for short termCa, PO4, Mg not required for short term

5. Electrolytes Imbalance:

»Sodium

»Potassium

»Magnesium

»Calcium

Hyponatremia

Definition: Na < 135 mmol/l

Clinical manifestation (<120mmol/l)

Causes 1. Hypotonic (Posmol < 275)

a. Hypovolumicb. Euvolumic

2. Isotonic (pseudo) (Posmol 275-295)

3. Hypertonic

1. Hypervolumic (Posmol >295)a. Urinary Na >20b. Urinary Na < 20

Management

General principle:

• Serum Na should not be increased > 10 mmol/L (asymptomatic) OR 12 mmol/l in symptomatic

• If Na >120 aggressive correction generally not required

• If Na <110 urgent treatment is required

Hypervolumic hyponatremia

• Restriction of Na & water intake

• Correction of K & promotion of water loss in excess of Na

• Treat aetiology

Isovolumic hyponatremia

a.No or mild symptoms;• Fluid restriction (800-1000cc) until Na rises• 0.9% saline with ferusamide may also be

used especialy in those with higher urine osmolality

b. Severe symptoms• Seizure & coma require rapid increase of

patient’s extracellular tonicity i.e: 3mmol/L in 3 hours

• Severe confusion need moderate increment 3-6 mmol in 12 hours

• The principle is to administer 3% saline at a rate equal to frusemide urinary electrolyte losses

• This approach avoid dangerous over expansion of ECF & correct primary cause of hyponatremia – excessive body water

Example:

60 kg isovolumic male patient presented with grand mal seizure with na: 111mmol/L. How to correct this?

Hypovolumic hyponatremia

• Rehydration over 2-3 days

• Amount of fluid calculated as:o Amount depleted: Calculated from degree of

dehydration (i.e 5% x BW x 1000cc)oNormal fluid requirement

• Rate: o ½ calculated deficit+maintanence+losses may

be given in first 24 hourso About ½ of total 24 hours volume may be given

in first 8 hours

Hypernatremia

• Definition: Na > 150 mmol/l

• Clinical manifestation (<160 mmol/l)

Causes

1. Loss of watera) Reduced water intake

b) Water loss in excess of sodium

2. Gain of sodiuma) Increase intake

b) Renal salt retention

Management

General principle:

• Target of fall 10mmol/L/day in all patient*

• Long standing hyponatremia – infusion of hypertonic saline may cause cerebral edema (rate 0.5 mmol/hr)

• Acute hypernatremia may not increase risk of cerebral edema upon fast correction (i.e 1 mol/hr)

1. Loss of water - see example

2. Salt Gain• The aim is to remove sodium rapidly using

potent diuretics & at the same time D5% is infused

• In severe difficult cases- dialysis is needed

Example:

60kg female hypovolumic patient presented with sever obstundation with Na level of 165 mmol/l? How to correct this

Hyperkalemia

• Definition: K > 150 mmol/l

• Symptoms: nausea, vomitting, intestinal colic, weakness, respiratory failure

• Signs: peaked T wave, flattened P wave, prolonged PR interval, widened QRS, sine wave formation and VF

Causes

1. Abnormal potassium distribution

2. Factitious

3. Oliguric renal failure

4. Impaired renin / aldosterone axis

5. Inhibition renal potassium secretion

6. Increase intakea) Endogenous

b) Exogenous

Management

Goals:

• To protect heart from effects of K by antagonizing its effect on cardiac conduction (ca gluconate)

• To shift K from ECF to ICF (NaChO3, insulin, glucose)

• To reduce total body K (cation-exchange resin, dialysis)

Recommendation

• Mild to moderate hyperkalemia (k: 5,5-6.5) with no ECG changes– Low K diet– Stop offending drug– Cation exchange resin– Correction of acodosis– +/- Glucose and insulin infusion

• Severe hyperkalemia (k>6.5mmol/L) or ECG changes:– Above treatment– Immediate calcium administration– Glucose & insulin infusion– Other methods i.e dialysis

Method of correction

1. Calcium administration– 10 ml of 10% calcium gluconate IV slow

bolus

2. Glucose & insulin infusion- Rapid 10U insulin + 50 ml of 50% Dextrose

as slo bolus

3. Beta-agonist therapy- Iv salbutamol 0.5 mg IV in 15 min or 10 mg

nebulizer

4. Sodium bicarbonate infusion- Iv NaCH03 100-200 mmol/L over 30 min

5. Cation-exchange resins- Oral kalimate 10g tds

6. Hemodialysis

Hypokalemia

• Definition: K > 3.5 mmol/l

• Symptoms: constipation, ileus, muscle weakness, fatigue

• Signs: Diminished tendon reflex, U-wave, flattened T-wave, ST segment changes, arrhythmias

Causes

1. Shift into cells

2. Reduced intake

3. Increased lossa) Renal

b) GIT

c) Misc

Management

Important facts:

• 1 g KCL contains 14 mmol K

• Magnesium depletion should be suspected if K level does not rise after adequate oral therapy

• K is an extracellular cation; a low serum K level reflects a much greater total K deficit

Oral therapy:

• Mild to moderate ( K >2.5)

• Oral KCL 1-2g every 2-4 hourly

• Slow-release K (1 tab = 8 mmol) or effervescent K (1 tab = 14 mmol) or mist KCL

• Off/change drug causing hypokalemia

IV therapy:

• Severe hypokalemia (<2.5 mmol/L), with ECG changes, and in patient who are not able to take orally and who are symptomatic

• Asymptomatic patient: – Concentration < 40 mmol/L (<3g KCL/l) in

dextrose-free carrier• Emergency: up to 40 mmol/L (i.e KCL 3g/hr)

and in concentration of 200-400 mmol/L*

Hypocalcemia

• Definition: corrected Ca < 2.0

• Clinical manifestation when Ca < 1.5

• Symptoms: Paresthesia, cramp, weakness, confusion, seizure

• Sign: increase DTR, chvostek’s sign, Trouseau’s sign, prolonged QT, T wave inversion, VF

Causes

Management

1. Acute symptomatic• 10-20cc 10% calcium gluconate over 10 min

followed by infusion at 0.5-2mg/kg/hr*• Avoid recurrent symptomatic hypocalcemia &

maintain calcium at 2-2.25 mmol/l• Treat hypomagnesium• Cardiac monitoring

2. Long term

• Oral calcium supplement i.e calcium lactate

• Vitamin D i.e calcitriol, alfacalcidol

Hypercalcemia

• Definition: Ionized Ca > 2.7 mmol/l

• Symptoms: depression, confusion, stupor, coma, polyuria, polydipsia, nausea, vomitting, abdominal pain, constipation.

• Sign: QT interval, prolonged PR and QRS intervals, increased QRS voltage, T-wave flattening and widening and AV block.

Causes

Management

• Rehydration!

• Steroids

• Calcitonin

• Biphosponates

• Mithramycin

• Dialysis

Hypomagnisium

• Symptoms: delirium seizure

• Sign: similar to calcium deficiency, including hyperactive reflexes, muscle tremors, and tetany with a positive Chvostek’s sign.

• ECG changes include:prolonged QT and PR intervals, ST-segment depression, flattening or inversion of P waves, Torsades de pointes, and arrhythmias

Causes

• Poor intake (starvation, alcoholism, prolonged use of intravenous fluids, and total parenteral nutrition)

• Renal loss (alcohol, most diuretics, and amphotericin B),

• GI losses (diarrhea), malabsorption, acute pancreatitis, diabetic ketoacidosis, and primary aldosteronism.

Management

• Mild or chronic hypomagnesium– Oral elemental magnesium of 240 mg od-bd– A/e: diarrhea

• Severe hypomagnesium– Iv magnesium comes in 49.3% 5ml solution

(2.47g/5ml)– 1-2 g magnesium sulphate over 15 min

(MgSo4 at 25-30 mg/kg dilute in normal saline)

– Then maintain similar dose given in 4-8 hours for a day

– Monitor Mg, Ca,

Special Surgical Consideration

• SIADH

• Diabetis insipidus

• Cerebral salt wasting

• Re-feeding syndrome

• Malignancy

SIADH

• Inclusive criteria:– Plasma Na < 130 mmol/L– Plasma osmolality <275 mOsml/kg– Urine Na > 20 mmol/L– Urine osmolality > plasma osmolality– No sign of overload– Normal renal, thyroid adrenal function

Refeeding syndrome

– Occurs in severely malnourished patient

– Rapid nutritional repletion leads to:• Severe fluid and electrolytes disturbances• Dextrose infusion leads to surge of insulin then

leads to K and phosphorus intracellular shift → respiratory failure and cardiac decompensation →death

Cerebral Salt Wasting Syndrome

• CSWS is a volume depleted state with negative Na balance secondary to primary natriuresis

• As in SIADH, CSWS is common in intracranial disease. Presentation & ix may overlap

• Treatment - fluid administration to achieve normovolemia

Fluid Glucose (g)

Na (mmol/l)

K (mmol/l)

Cl (mmol/l)

HCO3 (mmol/l)

Osmolality (mOsmol/l)

Cal (Kcal/l)

D5% 50 0 0 0 0 252 200

D10% 100 0 0 0 0 505 400

D50% 500 0 0 0 0 2525 2000

0.45% NS 0 77 0 77 0 154 0

NS 0 154 0 154 0 308 0

D5/0.22NS 50 38 0 38 0 329 200

D5/NS 50 154 0 154 0 406 200

LR 0 130 4 110 27 272 <10

D5/LR 50 130 4 110 27 524 210

ALBUMIN (5%)

0 145 0 145 0 330 200

ALBUMIN (25%)

0 145 0 145 0 330 1000

References

• Schwartz Manual of Surgery; 8th edition (2008)

• Tintinalli Emergency Medicine; 6th Edition

• Sarawak Handbook of Emergency Medicine; 2nd edition

• Emergency Medicine (Facts). International Version (2001)

• Emedicine.medscape.com