Fluid and Electrolyte Management of the Surgical Patient

Jaffar AlkhuzaieM.B.B.Ch, AFRCSI, CABS

Introduction

Fluid and electrolyte management are paramount to the care of the surgical patient. Changes in both fluid volume and electrolyte composition occur preoperatively, intraoperatively, and post operatively, as well as in response to trauma and sepsis.

Case 1

40 years old maleSBONGT 1500 mlNa 150K 2.9

Total Body Water

50-60% of total body weightWho is having higher proportion of body weight as water? And Why?

Males or FemalesLean or ObeseYoung or elderly

Muscle and solid organs have higher water content than fat and boneHigher proportion of water in:

Young Lean Males

Fluid Compartments

Composition of Fluid Compartments

Classification of Body Fluid Changes

Normal Exchange of Fluid and ElectrolytesDisturbances in Fluid BalanceVolume ControlConcentration Changes

HyponatreamiaHypernatreamia

Composition ChangesHyperkalemiaHypokalemiaHypermagnesemiaHypomagnesemiaHypercalcemiaHypocalcemiaHyperphosphatemiaHypophosphatemia

Case 2

50 years old female Not know to have medical problemSBO due to adhesionsOn NGT Total intake 2700 mlTotal out put 2800 ml

Normal Exchange

Normal person consumes 2000ml of H2O75% oral intakeRest from solid foods

Daily water losses1L in Urine250 ml in stool600 insensible losses

Skin 75%Lungs 25%

Disturbances in Fluid Balance

Extracellular volume deficit: most common in surgical patients

AcuteCardiovascularCentral nervous system

ChronicDecrease skin turgorSunken eyes& CVS and CNS

Volume ExcessVolume DeficitSystem

Weight gain Peripheral edema

Weight loss Decreased skin turgor

Generalized

*Increased cardiac output *Increased central venous pressure *Distended neck veins *Murmur

*Tachycardia *Orthostasis/

hypotension *Collapsed neck veins

Cardiac

Oliguria Azotemia

Renal

Bowel edema IleusGastrointestinal

Pulmonary edema Pulmonary

Composition of Gastrointestinal SecretionsHCO 3

-

mEq/LClmEq/L

KmEq/L

NamEq/L

VolumemL/24 h

Type ofSecretion

0100-13010-3060-901000-2000Stomach30-4090-1205-10120-1402000-3000Small intestine

0403060 Colon95-11570-905-10135-145600-800Pancreas

30-4090-1105-10135-145300-800Bile

Case 3

78 years old male Not know to have any medical problemHad sigmoid colectomy for Ca2nd day post opNa 130

Hyponatremia

CausesSodium depletionSodium dilution

Sodium depletion

Decrease intakeLow Na dietEnteral feeds

Increase lossGastrointestinal Losses

VomitingProlonged NGT suctioningDiarrhea

Renal LossesDiureticsPrimary renal disease

Depletional hyponatreamia is often accompanied by extracellulr volume deficit

Sodium dilution

Due to excess extracellular waterIntentional: excessive oral intakeIatrogenic: Intravenous

Increase ADHIncrease reabsorption of water from the kidneys

DrugsAntipsychoticsTricyclic antidepressantsAngiotensin-converting enzyme inhibitors

Physical signs: usually absent Lap: hemodilution

HyperosmolarMannitolHyperglycemia

PseudohyponatremiaPlasma lipidsPlasma proteins

HyponatremiaBody System

Headache, confusion, hyper- or hypoactive deep tendon reflexes, seizures, coma, increased intracranial pressure

Central nervous system

Weakness, fatigue, muscle cramps/twitchingMusculoskeletal

Anorexia, nausea, vomiting, watery diarrheaGastrointestinal

Hypertension and bradycardia if significant increases in intracranial pressure

Cardiovascular

Lacrimation, salivationTissue

OliguriaRenal

Management of Hyponatremia

Exclude Hyperosmolar causesDepletion versus dilutionDehydration or over hydrated Normal volume >>evaluate ADHNa losses

Urine Na <20 mEq/L = extrarenalUrine Na >20 mEq/L = Renal

Free water restrictionIf sever administration NaIf neuralgic symptoms are present

3% N.SNo more than 1 mEq/L per hourUntill reaches 130 mEq/L or neurological symptoms improve

If asymptomatic 0.5 mEq/L per hour maximum 12 mEq/L per day

Hypernatremia

Loss of free waterGain sodium in excess

HypernatremiaBody System

Restlessness, lethargy, ataxia, irritability, tonic spasms, delirium, seizures, coma

Central nervous system

WeaknessMusculoskeletal

Tachycardia, hypotension, syncopeCardiovascular

Dry sticky mucous membranes, red swollen tongue, decreased saliva and tears

Tissue

OliguriaRenal

FeverMetabolic

TreatmentIn hypovolemic patients, volume should be restored.Water deficit is replaced using a hypotonic fluid

Water deficit (L)=(serum sodium -140 /140) * TBWTBW = 50% for lean men and 40% for women

No more than 1 mEq/h and 12 mEq/d for acute.

Case 4

40 years old male Polytrauma# Rt femur and blunt abdominal injuryK 2.9

OliguriaAnd on going blood transfusion

Case 5

40 year old male Case of crohns with entero-cutenousfistulaOn TPNK 6.5

Potassium

Average intake of potassium 50-100 mEq/d2% of totall body potassium is located within extracellular compartmentNormal range 3.5-5.0 mEq/L

Hyperkalemia

Excessive potassium intakeOralIntravenousBlood transfusions

Increased release of potassium from cellsHemolysisRhabdomolysisCrush injuriesGastrointestinal hemorrhageAcidosisRapid increase of extracellular osmolality

Impaired excretion by the kidneys Potassium sparing diureticsAngiotensin-Converting enzyme inhibitorsNonsteroidal antiinflammatoriesRenal insufficiency and renal failure

Symptoms Gastrointestinal

NauseaVomitingIntestinal colicDiarrhea

NeuromuscularWeaknessAscending paralysis to respiratory failure

CardiovascularECG changes

Peaked T wavesFlattened P waveProlonged PR intervalWidened QRS complexVentricular fibrillation

Cardiac arrhythmiasArrest

Discontinue exogenous potassiumCation-exchange resin, KayexalateGlucoseInsulinCalcium chloride or calcium gluconateAll the above measures are temporary lasting from 1 to 4 hoursDialysis should be considered

HypokalemiaMore common in surgical patientInadequate intake

DietaryPotassium free IV fluids Total parenteral nutrition with inadequate potassium replacement

Excessive renal excretionHyperaldosteronismMedications

Loss in gastrointestinal secreationsVomitingHigh NGT output

Intracellular shift Metabolic alkalosisInsulin therapy

Drugs induce magnesium depletionAmphotericinAminoglycosidesFoscarnetCisplatinifosfamide

SymptomsGastrointestinal

ileusConstipation

NeuromuscularWeaknessFatigueDiminished tendon reflexes Paralysis

CardiacCardiac arrestECG changes

U wavesT wave flatteningST segment changesArrhythmias

Potassium repletionOrally or intravenousIn IV no more than 10 to 20 mEq/h40 mEq/h when ECG monitoringCaution with oliguria or impaired renal function