96/03/27 Book Reading

Fluid and Electrolyte Management of the Surgical Patient

Intern 9031119

Outline • Body fluids / Disturbance / Therapy • Electrolytes abnormalities : Sodium, Potassium, Mgnesium, Calcium, Phosphorus

Body Fluids • TBW: 50-60% total body weight ¼ plasma

2/3 ICF

K+, Mg++ phosphate, proteins 290mOsm

1/3 ECF Na+ Cl-, HCO3---

310 mOsm

¾ Interstitial fluid

• Serum osmolality: 2 Na+ + glucose/18 + BUN/2.8

Daily water loss

Disturbance in Fluid Balance • Extracellular volume deficit The most common fluid disorder in surgical P’t Loss of GI fluid ……

• Extracellular volume excess iatrogenic, renal dysfunction, CHF, cirrhosis…..

Fluid and Electrolyte therapy:

Parenteral solutions • Isotonic: L/R, N/S Replace GI loss, ECF deficits • 0.45 % NaCl + 5 % Dextrose Maintenance fluid therapy ( post-op ), Replace ongoing GI loss 200 kcal / L

Fluid and Electrolyte therapy:

Alternative Resuscitative Fluids • Hypertonic saline solution ( 3.5, 5 %) Severe sodium deficit • Colloids effective volume expanders ?! Albumin Dextrans 7000

Hetastarch

4000 / 7000 Hydroxyethyl starch

Gelatins

Pre-operative Fluid Therapy Maintenance Fluids 0-10 Kg 100 ml/kg per day 11-20 kg 50 ml/kg per day >20 kg 20 ml/kg per day

• • • •

Pre-Operative Volume Deficits Obvious GI loss + poor oral intake Third space losses Prompt fluid replacement Isotonic crystalloid

Intraoperative Fluid Therapy • Loss of compensatory mechanism due to anesthesia hypotension • Continued third space fluid losses

Post-Operative Fluid Therapy • Bases on current estimated volume status + ongoing fluid loss

• isotonic fluids

0.45 % saline + dextrose • potassium : renal function, urine output

Body Fluids • TBW: 50-60% total body weight ¼ plasma

2/3 ICF

K+, Mg++ phosphate, proteins 290mOsm

1/3 ECF Na+ Cl-, HCO3---

310 mOsm

¾ Interstitial fluid

• Serum osmolality: 2 Na+ + glucose/18 + BUN/2.8

Hypernatremia 1. Hypervolemic: excess sodium containing fluids, mineralcorticoid… urine [Na] > 20 mEq / L, osmolarity > 300 mOsm/L 2. Norvolemic, hypovolemic : water losss Renal causes

Non-renal causes

Urine [Na+]

< 20

< 15

Urine osmolarity

< 300-400

>400 mOsm/L

mEq / L

mOsm / L

Correction of Electrolytes Abnormalities:

Hypernatremia • S/S : rare, unless > 160 mEq / L, CNS effect •

in serum Na: < 1 meq/L/h, < 12 mEq/L/ 24h

• 5% dextrose

avoid overly rapid correction

Hyponatremia • Sodium depletion or dilution Dilution: post-op patient : ADH Depletion: decrease intake, increase loss • Excess solute: hyperglycemia, mannitol… • Pseudohyponatremia: plasma lipid, protein

Serum Osmolality: 2 Na + glucose/18 + BUN/2.8

Corrected [Na]

Plasma glucose 100 mg/dL plasma Na 1.6 meQ/L

Post-OP P’t ADH

Hyponatremia

Correction of Electrolytes Abnormalities:

Hyponatremia • S/S does not occur until serum Na < 120 mEq/L • Neurologic symptoms present 3% N/S, no more than 1 mEq/L/h (no more than 8 mEq/L in the first 24 hours ) serum Na >130 mEq/L or improved symptoms • Asymptomatic : < 0.5 mEq/L maximal increase: 12 mEq / L / day

Potassium Abnormalities Ileus, constipation, Hypokalemia Inadequate intake weakness, fatigue, excretion Magnesiun depletion tendon reflex , paralysis, cardic arrest,, Hyperkalemia Excesses intake N/V, intestinal colic, diarrhea, release from cell excretion by kidney weakness, fatigue, respiratory failure,

EKG pattern in Potassium abnormalities • U wave • T-wave flattening • ST changes • Arrythmia • peak T • flatten P • PR prolong • wide QRS • VF Merck and The Merck Manuals

Correction of Electrolytes Abnormalities:

Hypokalemia • Oral repletion: Mild, asymptomatic • IV repletion : < 10-20 mEq/ L /h ……. no monitor < 40 mEq/ L /h ……… EKG monitor

Correction of Electrolytes Abnormalities:

Hyperkalemia • • • • •

Discontinue all exogenous sources Cation-exchange resin : kayexalate Glucose + insulin Bicarbonate EKG changes: calcium choride or calcium gluconate (5-10 ml , 10%)

• Dialysis

Calcium Abnormalities • Total serum calcium is affected by albumin 0.8 mg / dL in calceium for 1g/dL in albumin • Ionized fraction •

neuromuscular stability

PH affect the ionized level ex acidosis protein binding

ionized calcium

Calcium abnomalities • Hypercalcemia: hyperparathyroidism malignancy

• Hypocalcemia: pancreatitis, massive soft tissue infection, malignancy with osteoclastic activity ….

Correction of Electrolytes Abnormalities:

Calcium abnomalities • Symptonatic hypercalcemia: ( > 12 mg/dL ) Repleting the associated volume deficit Brisk diuresis with normal saline • Symptomatic Hypocalcemia: IV 10 % calcium gluconate ( 7-9 mg/dL ) correct the associated deficits in Mg+, K++, PH

Correction of Electrolytes Abnormalities

Magnesium abnormalities • Hypermagnesium: withhold exogeneous sourses correct volume deficit calcium chloride (5-10 ml) dialysis • Hypomagnesium hypocalcemia persistent hypokalemia oral or IV , for severe deficit

Correction of Electrolytes Abnormalities

Phosphate Abnormalites

• Hyperphosphatemia: phosphate binder, calcium acetate, dialysis • Hypophosphatemia: oral or IV supplementation

Thanks *^_^*

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