GRACE C FIRMALINO MD FPCS July 13 2020 Total Body Water TBW 50 60 of total body weight Relatively constant Reflection of body fat Lean tissues muscle solid organs gt fat bone Average young male 60 gt Average young female 50 ID: 1038885
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1. FLUID AND ELECTROLYTE MANAGEMENT OF THE SURGICAL PATIENTGRACE C. FIRMALINO, MD, FPCSJuly 13, 2020
2. Total Body Water (TBW)50 – 60% of total body weightRelatively constantReflection of body fatLean tissues (muscle, solid organs) > fat, boneAverage young male 60% > Average young female 50%Estimates adjusted by 10 to 20% downward for obese and upward for malnourishedHighest in newborns – 80%
3. FLUID COMPARTMENTSTBW divided into three compartmentsPlasmaInterstitialIntracellularPlasma (5%) and interstitial fluid (15%) make up the extracellular fluid compartment – 1/3 of TBW or around 20% of total body weight Intracellular fluid – 2/3 TBW or around 40% of total body weight
4. FLUID COMPARTMENTSECF – sodium (principal cation) and chloride and bicarbonate (principal anions)ICF – potassium, magnesium (cations); phosphate and sulfate (anions) and proteins
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6. BODY FLUID CHANGESHealthy person consumes 2000ml of water per day75% oral intakeDaily lossesUrine – 800 to 1200 mlStool – 250 mlInsensible – 600 ml (skin 75% and lungs 25%)
7. BODY FLUID CHANGESDisturbances classifiedVolume changesConcentration changesComposition changesMay occur simultaneously
8. VOLUME CHANGESMainly involves water and sodiumWater moves freelySodium confined to the ECFSodium-containing fluids expands both intravascular and interstitial space (1:3)Sensed by osmoreceptors and baroreceptors Osmoreceptors – thirst, vasopressin (increases water reabsorption)Baroreceptors – aortic arch and carotid sinuses; neural (parasympathetic and sympathetic) and hormonal (renin-angiotensin, aldosterone, atrial natriuretic peptide)Alterations in renal sodium excretion and free water reabsorption restores volume to normal state
9. Extracellular volume deficit – most common fluid disorder in surgical patientsAcute or chronicGI losses – most common cause (diarrhea, vomiting, NGT suctioning, fistula)Sequestration secondary to soft tissue injuries, burn, peritonitis, obstruction, prolonged surgery (third-space losses)Extracellular volume excess – iatrogenic or secondary (renal dysfunction, congestive heart failure, cirrhosis)Usually tolerated by fit patients
10. Composition of GI secretionsVOLUME (mL/24 hr)Na (mEq/L)K (mEq/L)Cl (mEq/L)HCO3- (mEq/L)Stomach1000-200060-9010-30100-1300Small intestine2000-3000120-1405-1090-12030-40Colon6030400Pancreas600-800135-1455-1070-9095-115Bile300-800135-1455-1090-11030-40
11. Signs and Symptoms of Volume DisturbancesVOLUME DEFICITVOLUME EXCESSGeneralizedWeight lossWeight gainDecreased skin turgorPeripheral edemaCardiacTachycardiaIncreased cardiac outputOrthostasis/hypotensionIncreased central venous pressureCollapsed neck veinsDistended neck veinsMurmurRenalOliguriaAzotemiaGIIleusBowel edemaPulmonaryPulmonary edema
12. CONCENTRATION CHANGESChanges in serum sodium concentration inversely proportional to TBWHyponatremiaDepletion or dilutionHypernatremiaLoss of free water or gain of sodium in excess of water
13. CLINICAL MANIFESTATIONS OF ABNORMALITIES IN SERUM SODIUM LEVELHYPONATREMIAHYPERNATREMIACentral nervous systemHeadache, confusion, hyper/hypoactive DTR, seizures, coma, increased ICPRestlessness, lethargy, ataxia, seizures, coma, tonic spasms, deliriumMusculoskeletal Weakness, fatigue, muscle cramps/twitchingWeaknessGIAnorexia, nausea, vomiting watery diarrheaCardiovascularHypertension and bradycardia (inc ICP)Tachycardia, hypotension, syncopeTissueLacrimation, salivationDry sticky mucosa, red swollen tongue, decreased saliva and tearsRenalOliguriaOliguriaMetabolicFever
14. Hypernatremia – treatment of associated water deficits Volume restoration with normal salineReplacement of water deficit with hypotonic fluidWater deficit (L) = serum Na – 140 X TBW 140Decrease in serum Na concentration no more than 1mEq/hr and 12 mEq/day for acute and no more than 0.7mEq/hr for chronic to prevent cerebral edema and herniationHyponatremia – free water restriction for most cases; administration of sodium in severe (120mEq/L or less; neurologic symptoms)3% normal saline no more than 0.5 to 1mEq/L/hr (maximum 12mEq/L/day) until 130 mEq/L or neurologic symptoms improvePontine myelinolysis, seizures, weakness, paresis, akinetic movements, brain damage
15. COMPOSITION CHANGESPotassiumCalciumMagnesiumPhosphorus
16. COMPOSITION CHANGESHypokalemia – Inadequate intake, GI losses, excessive potassium excretionMore common in surgical patients than hyperkalemiaHyperkalemia – increased intake, increased release from cells, impaired excretionHypocalcemia – pancreatitis, massive soft tissue infections, renal failure, pancreatic and small bowel fistulas, hypoparathyroidism, abnormalities in magnesium level, tumor lysisHypercalcemia – primary hyperparathyroidism, malignancy
17. COMPOSITION CHANGESHyperphosphatemia – decreased urinary excretion (impaired renal function), increased intake (IV hyperalimentation solutions, phosphorus-containing laxatives), endogenous mobilization of phosphorus (rhabdomyolysis, hemolysis, sepsis, tumor lysis)Hypophosphatemia – decreased GI uptake (malabsorption) or decreased intake (malnutrition); respiratory alkalosis, refeeding syndromeHypermagnesemia – severe renal insufficiency, excess intake (TPN)Hypomagnesemia – poor intake, renal excretion, pathologic losses
18. Clinical Manifestations of Abnormalities in Potassium, Magnesium and Calcium LevelsINCREASED SERUM LEVELSSYSTEMPOTASSIUMMAGNESIUMCALCIUMGINausea/vomiting, colic, diarrheaNausea/vomitingAnorexia, nausea/vomiting, abdominal painNeuromuscularWeakness, paralysis, respiratory failureWeakness, lethargy, decreased reflexesWeakness, confusion, coma, bone painCardiovascularArrhythmia, arrestHypotension, arrestHypertension, arrhythmiaRenalPolyuria, polydipsiaDECREASED SERUM LEVELSGIIleus, constipationNeuromuscularDecreased reflexes, fatigue, weakness, paralysisHyperactive reflexes, muscle, tremors, tetany, seizuresHyperactive reflexes, parethesias, carpopedal spasm, seizuresCardiovascularArrestArrhythmiaHeart failure
19. Schwartz’s Principles of Surgery11th edition
20. FLUID THERAPYPARENTERAL SOLUTIONSIsotonic – lactated Ringer’s, normal salineUseful in correcting GI losses and correcting extracellular volume deficits
21. Schwartz’s Principles of Surgery11th edition
22. FLUID THERAPYPREOPERATIVEMaintenance for healthy individuals0-10 kg – 100ml/kg/day10-20kg – 50ml/kg/day>20kg – 20ml/kg/dayAssess status of patient and consider volume and electrolyte losses and include in correctionResuscitation should be guided by reversal of the signs of volume loss (vital signs, urine output 0.5 to 1ml/kg/hr in adults, corrected base deficit)
23. FLUID THERAPYINTRAOPERATIVECorrect known fluid lossesReplace ongoing losses500 to 1000ml per hour of balanced salt solutionPOSTOPERATIVECurrent estimated volume status and projected ongoing fluid lossesInitial postoperative period – isotonic solution24 to 48 hours – 5% dextroseLosses through vomiting, ngt, drains, urine ouput, insensible losses
24. REFERENCE: Schwartz’s Principles of Surgery 11th edition
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