5ICF ECF Major Cation Potassium Magnesium Sodium Major Anion Phosphate SulphateProteinChlorideBicarbonate
6OsmolarityMeasurement of the total solutes in a water solution per liter.Osmolarity = [sodiumx2 ]+urea/2.8+glucose/18Serum osmolarity is mOsm/LmOsmol/L- Isotonic> 300 mOsmol/L – Hypertonic< 280 mOsmol/L - Hypotonic
7Three categories of fluids Isotonic - Fluid has the same osmolarity as plasmaEg: Normal salineRingers lactate
8Hypotonic - Fluid has fewer solutes than plasma Eg : Water, 1/2 N/S (0.45% NaCl)
9Hypertonic - Fluid has more solutes than plasma Eg:5% Dextrose in Normal Saline (D5 N/S) , 3% saline solution.
27Case Study #1HPI:A 55 year old man is in the Neuro ICU for acute non hemorrhagic stroke.Hospital course:Decreasing urine output (< 0.5 ml/kg/hr) over the last 24 hours.What is your differential diagnosis? What diagnostic studies would you order?
29Case Study #1 Laboratory studies Serum studies Sodium 120 mEq/L BUN 4 mg/dL Chloride 98 mEq/L Creatinine 0.4 mg/dL Potassium 3.7 mEq/L Glucose 129 mg/dL Bicarbonate 25 mEq/L Osmolality 260 mosmol/kg Urine studies Specific gravity Sodium 58 mEq/L Osmolality 645 mosmol/kg What are the primary abnormalities?
30Case Study #1 Laboratory studies Major abnormalities 1) Hyponatremia 2) Oliguria (inappropriately concentrated urine) What is the most likely explanation for these findings?
31In Hyponatremia…… SIADH Renal water conservation Dilutional Cerebral salt wasting SyndromeNatriuresis with Dehydration
32Case Study #1 Syndrome of Inappropriate Antidiuretic Hormone (SIADH) Variable etiologyTraumaInfectionPsychosisMalignancyMedicationsDiabetic ketoacidosisCNS disordersPositive pressure ventilation“Stress”
33SIADHBy definition, “inappropriate” implies having excluded normal physiologic reasons for release of ADH:1) In response to hypertonicity.2) In response to life threatening hypotension.HyponatremiaOliguriaConcentrated urineelevated urine specific gravity“inappropriately” high urine osmolality in face of hyponatremiaNormal to high urine sodium excretion
34 urine osmolality, SG, urine sodium excretion Case Study #1 SIADHDiagnosisCritical level of suspicion.Demonstration of inappropriately concentrated urine in face of hyponatremia urine osmolality, SG, urine sodium excretionBe certain to exclude normal physiologic release of ADH
35Treatment Fluid restriction Avoid hypotonic fluids Case Study #1 SIADHTreatmentFluid restrictionAvoid hypotonic fluidsHypertonic saline / oral sodium chlorideFrusemide.
36Cerebral Salt wasting Syndrome Development of excessive natriuresis with hyponatremic dehydration in patients with intracranial diseaseSeen in Head injury, Brain tumor, Intracranial Surgery or stroke
37CSW vs SIADH features CSW SIADH Volume status Low Normal Wt Loss No changeOrthostatic signsPresentAbsentSr NaDecreasedHematocritIncreasedUric acidNormal or incResp to hydrationImprovementDec NaResp to fluid restPossible shockimproveUrine Na>100>20
38Case Study #1 The saga continues…. Hospital course: Four hours after beginning fluid restriction, you are called because the patient is having a generalized seizure. There is no response to two doses of IV lorazepam and a loading dose of fosphenytoin What is the most likely explanation?
39Case Study #1 The saga continues Seizure 1) Worsening hyponatremia 2) Intracranial event 3) Meningitis 4) Other electrolyte disturbance 5) Medication 6) Hypertension What diagnostic studies would you order?
40Case Study #1 The saga continues Stat labs: Sodium 110 mEq/L What would you do now?
41Case Study #1 Hyponatremic seizure TreatmentHypertonic saline (3% NaCl) infusionTo correct sodium to 125 mEq/L, the deficit is equal to0.6 X weight[kg] X (125 - measured sodium)0.6 X 60 X ( ) = 54O mEq
42Newer method Rate of infusion of 3%NaCl = Na Requirement x 1000 infusate sodium x time(Desired-Actual Na) x 0.6.body wt x 1000513 x no of hoursAs patient is symptomatic, rate of correction is 1 mEq/hr,Required rate of infusion of 3% NaCl = 1 x 0.6 x 60 x 1000513 x 1= 70 ml/hrCheck sodium after 4 hours and correct accordingly
44Case Study # 260 year old retired engineer presented to ER with history of inability to speak and move all 4 limbs since today morning. Detailed history revealed that he has been on naturopathy diet since 6 months and had developed GTCS 2 days back. He was treated outside for GTCS and following the treatment he is unable to communicate or use his limbs
45His previous lab reports showed Na is 117 mEq/L and rest of the parameters are within normal Limits Repeat Sodium in our hospital showed 145 mEq/LWhat could be the possibility?
46Central Pontine Myelinolysis Develops withAggressive treatment of Chronic hyponatremiaRaising Sr.Na >25mEq/L in first 48 hoursRaising Sr.Na to Normal or Above normal in 48 hours
47CPM Focal demyelination in the Pons & extrapontine areas. Causes Mutism / dysarthriaSpastic QuadriplegiaPseudobulbar palsySeizuresAltered Mental StatusComa & DeathCPM is irreversible
48Principles of Hyponatremia Management Asymptomatic Hyponatremia Use 0.9%NaClSymptomatic Hyponatremia Use 3% NaClCorrect only 12mEq/L defecit only perdayChronic Hypernatremia with severe symptoms should receive hypertonic saline only to arrest the symptoms and followed by slow 0.5 mEq/L
49Hyponatremia Management is Double Edged Sword KnowledgeWisdom
50Case Study #3HPI: A 5 month-old girl presents with a one day history of irritability and fever. Mother reports three days of “bad” vomiting and diarrhea. Home meds: Paracetamol and ibuprofen for fever PE: BP 70/40, HR 200, R 60, T38.3 C. Irritable, sunken eyes and fontanelle.
51Case Study #3No one can obtain IV access after 15 minutes, what would you do now?
52Case Study #3 Place intraosseous line Serum studies Bolus 40 ml/kg of isotonic salineReassessment (HR 170, RR 40, BP 75/40)Serum studiesSodium 164 mEq/L BUN 75 mg/dLChloride 139 mEq/L Creatinine 3.1 mg/dLPotassium 5.5 mEq/L Glucose 101 mg/dLBicarbonate 12 mEq/LpH pCO2 11pO HCO3 8
53Case Study #3What is the most likely explanation of this patient’s Condition?
54Case Study #2 Treatment of Hypernatremia To stop ongoing fluid lossTo correct water deficit= plasma Na – 140 x 0.6 x body wt. in kg140Water deficit can be replaced with water by mouth or IV 5% dextrose or 0.45% NaCl
55Rate Of CorrectionAcute Hypernatremia ½ body water defecit in 24 hoursChronic Hypernatremia ½ body water defecit in 48 hoursRapid correction cerebral edema & Neurological deterioration
56Case Study #4HPI:A 50 year old man was involved in a motor vehicle accident two days ago. He sustained an isolated head injury with intraventricular hemorrhage and multiple large cerebral contusions. Three hours ago, he had an episode of severe intracranial hypertension (ICP 90mm Hg, MAP 50mm Hg, requiring volume plus epinephrine infusion for hypotension. Over the last two hours, his urine output has increased to ml/hour
57What is your differential diagnosis? What test would you order?
58Case Study #4 Differential diagnosis Polyuria 1) Central diabetes insipidus Deficient ADH secretion (idiopathic, trauma, pituitary surgery, hypoxic ischemic encephalopathy) 2) Nephrogenic diabetes insipidus Renal resistance to ADH (X-linked hereditary, chronic lithium, hypercalcemia, ...) 3) Primary polydipsia (psychogenic) Primary increase in water intake (psychiatric), occasionally hypothalamic lesion affecting thirst center 4) Solute diuresis Diuretics (lasix, mannitol,..), glucosuria, high protein diets, post-obstructive uropathy, resolving ATN, ….
59Laboratory studies Serum studies Other Sodium 155 mEq/L BUN 13 mg/dLChloride 114 mEq/L Creatinine 0.6 mg/dLPotassium 4.2 mEq/L Glucose 86 mg/dLBicarbonate 22 mEq/L Serum osmolality: 320 mosmol/kgOtherUrine specific gravity 1.005, no glucose.Urine osmolality: 160 mosmol/kgWhat are the main abnormalities?
60Case Study #4 Laboratory studies Major abnormalities1) Hypernatremia2) Polyuria (inappropriately dilute urine)What is the most likely explanation?
61Case Study #4 Diabetes Insipidus DiagnosisCentral Diabetes insipidus1) Polyuria2) Inappropriately dilute urine (urine osmolality < serum osmolality)May be seen with midline defectsFrequently occurs in brain dead patientsWhat should you do to treat this patient?
62Case Study #4 Diabetes Insipidus TreatmentADH preparations - dDAVP nasal spray 2-4 μg/dlPotentiate ADH effect – chlorpropamide, carbamazepine, NSAID’s.Increase ADH release – ClofibrateWarningClosely monitor for development of hyponatremia
64Case Study #4HPI:An 35 year old lady with Chronic kidney disease presents with irritability. She is on nightly peritoneal dialysis at home. The lab calls a panic potassium value of 7.1 meq/L. The tech says it is not hemolyzed.What do you do now?
65Case Study #4 Hyperkalemia TreatmentImmediately repeat serum potassium.Do not wait for confirmatory labs especially if ECG changes present.AnticipatoryStop potassium administration including feeds
66ECGWhat is this rhythm?What is your immediate treatment?
67Case Study #5 Hyperkalemia Control effectsAntagonism of membrane actions of potassium10% Calcium gluconate ml over minutes; may repeat x2Shift potassium intracellularlyGlucose 1 gm/kg plus 0.1 unit/kg regular insulinAlkali therapy - Sodium bicarbonate 1 mEq/kg IVInhaled 2 adrenergic agonist
68Removal of potassium from the body Loop / thiazide diureticsCation exchange resin: sodium polstyrene sulfonate (Kayexelate) 1 gm/kg PO or PR (or both)Dialysis
71Case Study #5HPI:A three year old boy is recovering from septic shock. He received 150 ml/kg in fluid boluses in the first 24 hours and has anasarca. You begin him on a frusemide infusion for diuresis. He develops severe weakness and begins to hypoventilate. You notice unifocal premature ventricular beats on his cardiac monitor.
72What is your differential diagnosis? What tests would you order?
73Case Study #6 Laboratory studies Serum studiesSodium 134 mEq/L BUN 11 mg/dLChloride 98 mEq/L Creatinine 0.4 mg/dLPotassium 2.4 mEq/L Calcium 9.2 mg/dLBicarbonate 27 mEq/L Phosphorus 3.2 mg/dLOtherECG: Unifocal PVC’sWhat is the main abnormality?
74Case Study #6 Laboratory studies Major abnormality1) HypokalemiaWhat would you do now?
75Case Study #6 Hypokalemia TreatmentOralSafest, although solutions may cause diarrheaIVdo not exceed 40 mEq/L or 10 – 20 mEq/hr potassium.- never give inj.Kcl directly intravenously.Replace magnesium also if low(25-50 mg/kg MgSO4)
77SummaryDisorders of sodium, water, and potassium regulation are common in critically ill.Diagnostic approach must be considered carefully for each patientStrict attention to detail is important in providing safe and effective therapy