Presentation on theme: "Fluid and Electrolyte Management of the Surgical Patient"— Presentation transcript:
1Fluid and Electrolyte Management of the Surgical Patient Basic Science9/08/09J. P. Stokes
2Case Presentation #128 y/o WM involved in MVC brought to 1W with GCS of 3 and hypotensive. Pt intubated and receives 2L of LR which stabilize HR and BP. Found to have extensive cerebral contusion and SAH. Admitted to ICU with plan by Neurosurgery to correct any coagulopathy and keep sodium >150. Placed on 3% Hypertonic saline with Q6 Na. After 6 hours in the ICU, the patients UOP increases to cc/hr. The next sodium is % discontinued and patient started on Vasopressin replacement and free water. Pt deteroriates and herniates due to cerebral edema.
3Case Presentation #255 y/o WF with low rectal cancer s/p neoadjuvant undergoes LAR with diverting ileostomy. Blood loss is 300cc, fluid for the case was 1.8L crytalloid, and the case lasted 3.5 hours. Post-operative the patient is hypotensive with minimal UOP. Patient receives several 1L boluses and BP and UOP improve. She continues to receive IVFs and her sodium on POD#3 is 128 and her sats are decreased. She is diuresed and improves. On POD #5, she is tolerating liquids and her ileostomy output is 2.8L for that 24 hour period. Her IVFs were discontinued due to her oral intake and the next morning her creatinine is 2.3. She is bolused, restarted on maintenance, and ileostomy replacement, along with anti-motility agents. Her creatinine improves and she is discharged on POD #7 with ileostomy output of 1L/day.
4OverviewTotal Body Water (TBW) – 50-60% of total body weight depending on gender (amount of adipose tissue)TBW is divided into extracellular (1/3) and intracellular (2/3) compartmentsExtracellular is divided into plasma (1/4) and interstitial fluid (3/4) – 5% and 15% of body weight, respectively
5QuestionsWhat is the amount in milliliters of the intracellular volume in a 70kg male?14,000 ml10,500 ml42,000 ml28,000 ml
6CompositionExtracellular – Sodium (+), Chloride (-) and Bicarbonate (-)Intracellular- Potassium, Magnesium (+), Phosphate and Proteins (-)Plasma – 154 mEq/L of cations/anionsMaintained by ATP-driven sodium-potassium pumps
7Osmotic pressureThe movement of water across a cell membrane depends primarily upon osmosis. This depends on solutes or osmotically-active particles.Calculated serum osmolality = 2 X Sodium + glucose/18 + BUN/2.8Normal mOsmCharge determines equivalents (1 mEq of sodium equals 1 mmol)
8QuestionsWhat is the calculated serum osmolality of a patient with a the following chemistry?Na 140, K 4, Cl 105, HCO3 25, BUN 28, Cr 1.0, Glc 180260280300320Bonus: What is the anion gap of this patient?
9Fluid Homeostasis Average person Intake - 2L of water per day (75% oral, 25% from solidsOutput – 1L of urine, 250ml of stool, 600ml of insensible loss (skin and lungs – pure water)Insensible losses increased by fever, hypermetabolism, and hyperventilationSweating is an active process and is electrolytes and waterAverage salt intake – 3-5 grams
10Fluid Balance System Volume down Volume UP Generalized Weight loss Weight gainDec. skin turgor Perp. EdemaCardiac Tachycardia Increased COOrthostasis Increased CVP HypotensionCollasped veins Bulging veins Murmur (flow
11GI secretions Type Volume Na K Cl HCO3– Stomach – – – –130 0Intestine 2000– – – –Colon Pancreas 600– – – –90 95–115Bile 300– – – –110 30–40
12Question What fluid do you replace NGT output with? D51/2NS LR 1/2NS with 20 mEq KCLD5W with 150 mEq NaHCO3
13Electrolyte Abnormalities SodiumHyponatremiaHypervolemic – Excess oral water intake, IV fluidsEuvolemic – Hyperglycemia, SIADH, Hyperlipidemia (pseudo)Hypovolemic – Decreased sodium intake or increased loss of sodium containing fluids, GI losses, renal losses (UrNa >20)HypernatremiaHypervolemic – Salt intake, Mineralcorticoid excessEuvolemic – Renal water loss (diuretics, DI), Nonrenal water loss (skin, GI)Hypovolemic – Adrenal failure, Osmotic diureticsSigns and Symptoms: CNS, MSK, GI, CV, etc.
15MagnesiumHypomagnesemia – Poor intake, increased renal excretion, GI losses (diarrhea)Hypermagnesemia – impaired renal function, excess intake (TPN)Magnesium plays an important role in potassium and calcium homeostasis
16Calcium/PhosphorusHypercalcemia – Primary hyperparathyroidism, malignancyHypocalcemia – Pancreatitis, renal failure, hypopara-, etc.Asymptomaic hypocalcemia can be due to hypoproteinemia, mainly albuminCorrection for albuminPhosphorus – renal, gastrointestinal
17Acid/Base Normal pH – 7.35-7.45 Metabolic vs. Respiratory Uncompensated vs. CompensatedpH, CO2, HCO3
18Anion Gap and Metabolic Acidosis Anion gap = (Na + K) – (Cl + HCO3)Normal: 12 +/- 4Non-gap acidosis: Hyperalimentation, Acetozolamide, RTA, Diarrhea, Ureteral diversion, pancreatic fistulasAnion gap acidosis – Methanol, Uremia, DKA, Paraldehyde, INH, Lactate, Ethylene glycol, Salicylate
19Metabolic AlkalosisNormal acid-base homeostasis prevents metabolic alkalosis from developing unless both an increase in HC03 generation and impaired renal excretion of HCO3 occurs.Generally associated with hypokalemia (pyloric stenosis)Etiology: Mineralocorticoid excess, loss from gastric secretions, exogenous, impaired exretion
20QuestionWhat is the electrolyte and acid/base disturbance in pyloric stenosis, and explain why the patient has paradoxical aciduria?
21Respiratory derangements HyperventilationHypoventilationInvolves minute ventilation (respiratory rate and tidal volume)Treatment directed at the cause
22Fluid therapyWhat are the concentrations of normal saline and lactated ringer’s?Na 154 and 130K 0 and 4Cl 154 and 109HCO3 0 and 28Ca 0 and 3
23QuestionWhat is the amount of dextrose per liter in D51/2NS? How many calories is in one liter? How many calories per hour if fluids 125 cc/hr?5grams50grams500grams500mg
24Treating Electrolyte Disturbances Hypernatremia – Correction of free water deficitWater deficit (L) =[(Na-140)/140] x TBWTBW at 50% in men and 40% in womenThe rate of fluid administered should be titrated to achieve a decrease in serum sodium of no more than 12 mEq/d.Rapid correction: cerebral edema, herniationHyponatremia – Free water restriction, sodium administrationNeurologic symptoms – 3% (No more than 1 mEq/L/hr); Complication: CPM
25Potassium CorrectionHyperkalemia: Reduce total body potassium, shift from extra- to intracellular, and protect cells from effects of increased potassiumWhat can kill my patient? EKG, calciumHow do I shift potassium? Bicarbonate, Glucose (Insulin), AlbuterolHow can I remove potassium? Lasix, Dialysis, Potassium binders (Kayexalate)
30QuestionWhat is the appropriate fluid and maintenance rate for a 4kg baby with pyloric stenosis? What would you use to bolus the baby and why?
31Special SituationsSIADH – Euvolemia and hyponatremia along with elevated urine sodium and urine osmolality; Tx: Free water restriction, diuresis, fluids (?), lithium, democyclineDI – Dilute Urine in the face of hypernatremia; Central and Nephrogenic; Tx: Free water, VasopressinRefeeding: Shift from fat to carbohydrate stimulates insulin release and uptake of electrolytes (PO4, Mg, K, Ca), hyperglycemia