Fluid and Electrolyte Fluid and Electrolyte Management of the Management of the

Surgical PatientSurgical Patient

Basic ScienceBasic Science

9/08/099/08/09

J. P. StokesJ. P. Stokes

Case Presentation #1Case Presentation #1 28 y/o WM involved in MVC brought to 1W 28 y/o WM involved in MVC brought to 1W

with GCS of 3 and hypotensive. Pt intubated with GCS of 3 and hypotensive. Pt intubated and receives 2L of LR which stabilize HR and and receives 2L of LR which stabilize HR and BP. Found to have extensive cerebral BP. Found to have extensive cerebral contusion and SAH. Admitted to ICU with plan contusion and SAH. Admitted to ICU with plan by Neurosurgery to correct any coagulopathy by Neurosurgery to correct any coagulopathy and keep sodium >150. Placed on 3% and keep sodium >150. Placed on 3% Hypertonic saline with Q6 Na. After 6 hours in Hypertonic saline with Q6 Na. After 6 hours in the ICU, the patients UOP increases to 500-the ICU, the patients UOP increases to 500-1000cc/hr. The next sodium is 168. 3% 1000cc/hr. The next sodium is 168. 3% discontinued and patient started on discontinued and patient started on Vasopressin replacement and free water. Pt Vasopressin replacement and free water. Pt deteroriates and herniates due to cerebral deteroriates and herniates due to cerebral edema. edema.

Case Presentation #2Case Presentation #2 55 y/o WF with low rectal cancer s/p neoadjuvant 55 y/o WF with low rectal cancer s/p neoadjuvant

undergoes LAR with diverting ileostomy. Blood loss is undergoes LAR with diverting ileostomy. Blood loss is 300cc, fluid for the case was 1.8L crytalloid, and the 300cc, fluid for the case was 1.8L crytalloid, and the case lasted 3.5 hours. Post-operative the patient is case lasted 3.5 hours. Post-operative the patient is hypotensive with minimal UOP. Patient receives hypotensive with minimal UOP. Patient receives several 1L boluses and BP and UOP improve. She several 1L boluses and BP and UOP improve. She continues to receive IVFs and her sodium on POD#3 continues to receive IVFs and her sodium on POD#3 is 128 and her sats are decreased. She is diuresed is 128 and her sats are decreased. She is diuresed and improves. On POD #5, she is tolerating liquids and improves. On POD #5, she is tolerating liquids and her ileostomy output is 2.8L for that 24 hour and her ileostomy output is 2.8L for that 24 hour period. Her IVFs were discontinued due to her oral period. Her IVFs were discontinued due to her oral intake and the next morning her creatinine is 2.3. She intake and the next morning her creatinine is 2.3. She is bolused, restarted on maintenance, and ileostomy is bolused, restarted on maintenance, and ileostomy replacement, along with anti-motility agents. Her replacement, along with anti-motility agents. Her creatinine improves and she is discharged on POD #7 creatinine improves and she is discharged on POD #7 with ileostomy output of 1L/day.with ileostomy output of 1L/day.

OverviewOverview

Total Body Water (TBW) – 50-60% of Total Body Water (TBW) – 50-60% of total body weight depending on total body weight depending on gender (amount of adipose tissue)gender (amount of adipose tissue)

TBW is divided into extracellular (1/3) TBW is divided into extracellular (1/3) and intracellular (2/3) compartmentsand intracellular (2/3) compartments

Extracellular is divided into plasma Extracellular is divided into plasma (1/4) and interstitial fluid (3/4) – 5% (1/4) and interstitial fluid (3/4) – 5% and 15% of body weight, respectivelyand 15% of body weight, respectively

QuestionsQuestions

What is the amount in milliliters of What is the amount in milliliters of the intracellular volume in a 70kg the intracellular volume in a 70kg male?male? 14,000 ml14,000 ml 10,500 ml10,500 ml 42,000 ml42,000 ml 28,000 ml28,000 ml

CompositionComposition

Extracellular – Sodium (+), Chloride Extracellular – Sodium (+), Chloride (-) and Bicarbonate (-)(-) and Bicarbonate (-)

Intracellular- Potassium, Magnesium Intracellular- Potassium, Magnesium (+), Phosphate and Proteins (-)(+), Phosphate and Proteins (-)

Plasma – 154 mEq/L of cations/anionsPlasma – 154 mEq/L of cations/anions Maintained by ATP-driven sodium-Maintained by ATP-driven sodium-

potassium pumpspotassium pumps

Osmotic pressureOsmotic pressure

The movement of water across a cell The movement of water across a cell membrane depends primarily upon membrane depends primarily upon osmosis. This depends on solutes or osmosis. This depends on solutes or osmotically-active particles.osmotically-active particles.

Calculated serum osmolality = 2 X Calculated serum osmolality = 2 X Sodium + glucose/18 + BUN/2.8Sodium + glucose/18 + BUN/2.8

Normal 280-300 mOsmNormal 280-300 mOsm Charge determines equivalents (1 Charge determines equivalents (1

mEq of sodium equals 1 mmol)mEq of sodium equals 1 mmol)

QuestionsQuestions

What is the calculated serum osmolality of a What is the calculated serum osmolality of a patient with a the following chemistry?patient with a the following chemistry?

Na 140, K 4, Cl 105, HCO3 25, BUN 28, Cr Na 140, K 4, Cl 105, HCO3 25, BUN 28, Cr 1.0, Glc 1801.0, Glc 180

260260 280280 300300 320320 Bonus: What is the anion gap of this patient?Bonus: What is the anion gap of this patient?

Fluid HomeostasisFluid Homeostasis

Average person Average person Intake - 2L of water per day (75% oral, 25% Intake - 2L of water per day (75% oral, 25%

from solidsfrom solids Output – 1L of urine, 250ml of stool, 600ml of Output – 1L of urine, 250ml of stool, 600ml of

insensible loss (skin and lungs – pure water)insensible loss (skin and lungs – pure water) Insensible losses increased by fever, Insensible losses increased by fever,

hypermetabolism, and hyperventilationhypermetabolism, and hyperventilation Sweating is an active process and is Sweating is an active process and is

electrolytes and waterelectrolytes and water Average salt intake – 3-5 gramsAverage salt intake – 3-5 grams

Fluid BalanceFluid BalanceSystemSystem Volume down Volume down Volume UPVolume UP

GeneralizedGeneralized Weight lossWeight loss Weight gainWeight gain

Dec. skin turgorDec. skin turgor Perp. EdemaPerp. Edema

CardiacCardiac TachycardiaTachycardia Increased COIncreased CO

OrthostasisOrthostasis Increased CVPIncreased CVPHypotensionHypotension

Collasped veinsCollasped veins Bulging veinsBulging veinsMurmur (flowMurmur (flow

GI secretionsGI secretions

Type Type Volume Volume Na Na K K Cl Cl HCO3– HCO3–

Stomach Stomach 1000–2000 1000–2000 60–9060–90 10–30 100–130 10–30 100–130 00

IntestineIntestine 2000–30002000–3000 120–140 5–10 90–120 30-40120–140 5–10 90–120 30-40

Colon Colon  6060 30 30 40 40 00

PancreasPancreas 600–800600–800 135–145 5–10135–145 5–10 70–90 70–9095–11595–115

BileBile 300–800300–800 135–145 5–10135–145 5–10 90–110 90–11030–4030–40

QuestionQuestion

What fluid do you replace NGT output What fluid do you replace NGT output with?with?

D51/2NSD51/2NS LRLR 1/2NS with 20 mEq KCL1/2NS with 20 mEq KCL D5W with 150 mEq NaHCO3D5W with 150 mEq NaHCO3

Electrolyte AbnormalitiesElectrolyte Abnormalities

SodiumSodium HyponatremiaHyponatremia

Hypervolemic – Excess oral water intake, IV fluidsHypervolemic – Excess oral water intake, IV fluids Euvolemic – Hyperglycemia, SIADH, Hyperlipidemia Euvolemic – Hyperglycemia, SIADH, Hyperlipidemia

(pseudo)(pseudo) Hypovolemic – Decreased sodium intake or increased loss Hypovolemic – Decreased sodium intake or increased loss

of sodium containing fluids, GI losses, renal losses (UrNa of sodium containing fluids, GI losses, renal losses (UrNa >20)>20)

HypernatremiaHypernatremia Hypervolemic – Salt intake, Mineralcorticoid excessHypervolemic – Salt intake, Mineralcorticoid excess Euvolemic – Renal water loss (diuretics, DI), Nonrenal Euvolemic – Renal water loss (diuretics, DI), Nonrenal

water loss (skin, GI)water loss (skin, GI) Hypovolemic – Adrenal failure, Osmotic diureticsHypovolemic – Adrenal failure, Osmotic diuretics

Signs and Symptoms: CNS, MSK, GI, CV, etc.Signs and Symptoms: CNS, MSK, GI, CV, etc.

PotassiumPotassium

Dietary intake 50-100 mEq/day; Dietary intake 50-100 mEq/day; primarily intracellularprimarily intracellular

Hyperkalemia – Excess intake, Hyperkalemia – Excess intake, increased release from cells, impaired increased release from cells, impaired excretion, medicationsexcretion, medications

Hypokalemia – Decreased intake, Hypokalemia – Decreased intake, Excess excretion, GI losses (direct vs. Excess excretion, GI losses (direct vs. indirect)indirect)

S/S: GI, CNS, CVS/S: GI, CNS, CV

MagnesiumMagnesium

Hypomagnesemia – Poor intake, Hypomagnesemia – Poor intake, increased renal excretion, GI losses increased renal excretion, GI losses (diarrhea)(diarrhea)

Hypermagnesemia – impaired renal Hypermagnesemia – impaired renal function, excess intake (TPN)function, excess intake (TPN)

Magnesium plays an important role Magnesium plays an important role in potassium and calcium in potassium and calcium homeostasis homeostasis

Calcium/PhosphorusCalcium/Phosphorus

Hypercalcemia – Primary Hypercalcemia – Primary hyperparathyroidism, malignancyhyperparathyroidism, malignancy

Hypocalcemia – Pancreatitis, renal Hypocalcemia – Pancreatitis, renal failure, hypopara-, etc.failure, hypopara-, etc.

Asymptomaic hypocalcemia can be Asymptomaic hypocalcemia can be due to hypoproteinemia, mainly due to hypoproteinemia, mainly albuminalbumin

Correction for albuminCorrection for albumin Phosphorus – renal, gastrointestinalPhosphorus – renal, gastrointestinal

Acid/BaseAcid/Base

Normal pH – 7.35-7.45Normal pH – 7.35-7.45 Metabolic vs. RespiratoryMetabolic vs. Respiratory Uncompensated vs. CompensatedUncompensated vs. Compensated pH, CO2, HCO3pH, CO2, HCO3

Anion Gap and Metabolic AcidosisAnion Gap and Metabolic Acidosis

Anion gap = (Na + K) – (Cl + HCO3)Anion gap = (Na + K) – (Cl + HCO3) Normal: 12 +/- 4Normal: 12 +/- 4 Non-gap acidosis: Hyperalimentation, Non-gap acidosis: Hyperalimentation,

Acetozolamide, RTA, Diarrhea, Acetozolamide, RTA, Diarrhea, Ureteral diversion, pancreatic fistulasUreteral diversion, pancreatic fistulas

Anion gap acidosis – Methanol, Anion gap acidosis – Methanol, Uremia, DKA, Paraldehyde, INH, Uremia, DKA, Paraldehyde, INH, Lactate, Ethylene glycol, SalicylateLactate, Ethylene glycol, Salicylate

Metabolic AlkalosisMetabolic Alkalosis

Normal acid-base homeostasis Normal acid-base homeostasis prevents metabolic alkalosis from prevents metabolic alkalosis from developing unless both an increase developing unless both an increase in HC03 generation and impaired in HC03 generation and impaired renal excretion of HCO3 occurs.renal excretion of HCO3 occurs.

Generally associated with Generally associated with hypokalemia (pyloric stenosis)hypokalemia (pyloric stenosis)

Etiology: Mineralocorticoid excess, Etiology: Mineralocorticoid excess, loss from gastric secretions, loss from gastric secretions, exogenous, impaired exretionexogenous, impaired exretion

QuestionQuestion

What is the electrolyte and acid/base What is the electrolyte and acid/base disturbance in pyloric stenosis, and disturbance in pyloric stenosis, and explain why the patient has explain why the patient has paradoxical aciduria?paradoxical aciduria?

Respiratory derangementsRespiratory derangements

HyperventilationHyperventilation HypoventilationHypoventilation Involves minute ventilation Involves minute ventilation

(respiratory rate and tidal volume)(respiratory rate and tidal volume) Treatment directed at the causeTreatment directed at the cause

Fluid therapyFluid therapy

What are the concentrations of What are the concentrations of normal saline and lactated ringer’s?normal saline and lactated ringer’s? Na 154 and 130Na 154 and 130 K 0 and 4K 0 and 4 Cl 154 and 109Cl 154 and 109 HCO3 0 and 28HCO3 0 and 28 Ca 0 and 3 Ca 0 and 3

QuestionQuestion

What is the amount of dextrose per What is the amount of dextrose per liter in D51/2NS? How many calories liter in D51/2NS? How many calories is in one liter? How many calories per is in one liter? How many calories per hour if fluids run @ 125 cc/hr?hour if fluids run @ 125 cc/hr? 5grams5grams 50grams50grams 500grams500grams 500mg500mg

Treating Electrolyte DisturbancesTreating Electrolyte Disturbances

Hypernatremia – Correction of free water deficitHypernatremia – Correction of free water deficit Water deficit (L) =[(Na-140)/140] x TBWWater deficit (L) =[(Na-140)/140] x TBW TBW at 50% in men and 40% in womenTBW at 50% in men and 40% in women

The rate of fluid administered should be titrated The rate of fluid administered should be titrated to achieve a decrease in serum sodium of no to achieve a decrease in serum sodium of no more than 12 mEq/d.more than 12 mEq/d.

Rapid correction: cerebral edema, herniationRapid correction: cerebral edema, herniation Hyponatremia – Free water restriction, sodium Hyponatremia – Free water restriction, sodium

administrationadministration Neurologic symptoms – 3% (No more than 1 Neurologic symptoms – 3% (No more than 1

mEq/L/hr); Complication: CPMmEq/L/hr); Complication: CPM

Potassium CorrectionPotassium Correction

Hyperkalemia: Reduce total body Hyperkalemia: Reduce total body potassium, shift from extra- to potassium, shift from extra- to intracellular, and protect cells from intracellular, and protect cells from effects of increased potassiumeffects of increased potassium What can kill my patient? EKG, calciumWhat can kill my patient? EKG, calcium How do I shift potassium? Bicarbonate, How do I shift potassium? Bicarbonate,

Glucose (Insulin), AlbuterolGlucose (Insulin), Albuterol How can I remove potassium? Lasix, How can I remove potassium? Lasix,

Dialysis, Potassium binders (Kayexalate)Dialysis, Potassium binders (Kayexalate)

Repleting ElectrolytesRepleting Electrolytes

Potassium: IV and PO/NGPotassium: IV and PO/NG Magnesium: IV (Important for Magnesium: IV (Important for

repleting other electrolytes)repleting other electrolytes) Calcium: IV and POCalcium: IV and PO Phosphorus: IV and PO (ineffective)Phosphorus: IV and PO (ineffective)

Treatment of ….Treatment of ….

Hypermagnesemia: Remove source, Hypermagnesemia: Remove source, calcium for cardiovascular effects, calcium for cardiovascular effects, dialysisdialysis

Hypercalcemia: Volume and diuresis, Hypercalcemia: Volume and diuresis, bisphosphonates, calcitoninbisphosphonates, calcitonin

Hyperphosphotemia: Phosphate Hyperphosphotemia: Phosphate binders, urinary exrection, dialysisbinders, urinary exrection, dialysis

Maintenance fluids/Post-opMaintenance fluids/Post-op

MaintenanceMaintenance 4, 2, 1 rule (Dextrose, Electrolytes)4, 2, 1 rule (Dextrose, Electrolytes) 5, 2, 1 rule in pediatric surgery5, 2, 1 rule in pediatric surgery

Boluses Boluses What fluid?What fluid?

Post-OpPost-Op

QuestionQuestion

What is the appropriate fluid and What is the appropriate fluid and maintenance rate for a 4kg baby with maintenance rate for a 4kg baby with pyloric stenosis? What would you use pyloric stenosis? What would you use to bolus the baby and why?to bolus the baby and why?

Special SituationsSpecial Situations

SIADHSIADH – Euvolemia and hyponatremia – Euvolemia and hyponatremia along with elevated urine sodium and along with elevated urine sodium and urine osmolality; Tx: Free water restriction, urine osmolality; Tx: Free water restriction, diuresis, fluids (?), lithium, democyclinediuresis, fluids (?), lithium, democycline

DIDI – Dilute Urine in the face of – Dilute Urine in the face of hypernatremia; Central and Nephrogenic; hypernatremia; Central and Nephrogenic; Tx: Free water, VasopressinTx: Free water, Vasopressin

RefeedingRefeeding: Shift from fat to carbohydrate : Shift from fat to carbohydrate stimulates insulin release and uptake of stimulates insulin release and uptake of electrolytes (PO4, Mg, K, Ca), electrolytes (PO4, Mg, K, Ca), hyperglycemiahyperglycemia