CWA Fluids & Electrolytes 2023 Fall Student Notes PDF

Integrated Learning Experience-I: Fall 2022 Fluids & Electrolytes Courtney Watts Alexander, Pharm.D., BCPS, BCOP Assistant Professor, Clinical Pharmacogenomics Department of Pharmacy Practice, AUHCOP Email: [email protected] 2023 1 Objectives Unit 5.1: Foundational Knowledge 1. Describe the basic...

Integrated Learning Experience-I: Fall 2022 Fluids & Electrolytes Courtney Watts Alexander, Pharm.D., BCPS, BCOP Assistant Professor, Clinical Pharmacogenomics Department of Pharmacy Practice, AUHCOP Email: [email protected] 2023 1 Objectives Unit 5.1: Foundational Knowledge 1. Describe the basic anatomy of the kidney. (1a, c-f) 2. Describe the basic anatomy of the nephron. (1a, c-f) 3. Describe filtration, secretion and reabsorption in the kidney (1a, c-f) 4. Describe fluid homeostasis and how fluid and electrolytes are handled by the kidney. (1a, 1d) a. sodium b. Potassium c. Phosphorous d. Magnesium e. Calcium f. Chloride g. Glucose h. Bicarbonate 5. Define extracellular, intracellular, intravascular and interstitial fluid compartments. (1a) 6. Describe fluid movement between the compartments. (1a) 7. Describe the etiology of fluid loss/balance. (1a) 8. Describe insensible fluid losses. (1c) 9. Define isotonic, hypotonic and hypertonic. (1d) 10. List which electrolytes primarily occur intracellularly versus extracellularly. (1a) 11. Identify the primary role of electrolytes within the human body. (1a) 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. Identify normal ranges for common electrolytes within the human body. (1c) Identify risk factors that are associated with fluid imbalances. (1b) Identify risk factors that are associated with electrolyte imbalances. (1b) Identify comorbid disease states that are commonly associated with fluid imbalances. (1b) Identify comorbid disease states that are commonly associated with electrolyte imbalances. (1b) Describe how fluid imbalances are detected and evaluated. (1c) Describe how electrolyte imbalances are detected and evaluated. (1c) Describe common patient presentations for volume depletion, dehydration, and edema. (1c) Describe common patient presentations for hypernatremia, hyperkalemia, hypermagnesemia, hyperphosphatemia. (1c) Describe common complications of fluid imbalances. (1f) Describe common complications of electrolyte imbalances. (1f) Given a patient case, determine if a patient has volume depletion, dehydration, edema or is euvolemic. (1c) Given a patient case, determine if a patient has electrolyte imbalances. (1c) Name 3 fluid types and give an example of each fluid type. (1d) Calculate Creatinine Clearance (CrCl) utilizing the Cockcroft Gault equation for an adult male and an adult female. (66) Objectives Unit 5.2: Review 1. Given a patient with a fluid imbalance identify pertinent subjective and objective information needed to formulate an assessment. (22) 2. Given a patient with an electrolyte abnormality, identify pertinent subjective and objective information needed to formulate an assessment. (22) 3. Given a list of fluids, use the ISMP lists to identify high-alert medications or classes of medications. (192) 4. Given a list of electrolytes, use the ISMP lists to identify high-alert medications or classes of medications. (192) Unit 5.3: Assessment 1. Given a patient case, formulate an assessment for the fluid and/ or electrolyte imbalance. (23) 2. Calculate the daily and hourly fluid requirements when given the replacement rate. (66) 3. Assess fluid status in a patient upon initial presentation (38) 4. Assess electrolyte levels in a patient upon initial presentation (38) Disclaimer! • Do not memorize normal values for ILE-I! • You will be provided normal values • Always consult the laboratory reference range for determination of normal value • Resources & laboratories may have slight variations Common Labs – Electrolyte Panels • Basic Metabolic Panel (BMP) • AKA “Chem 7”, “Chemistry” • Complete Metabolic Panel (CMP) • AKA ”Chem 14” 1. 2. 3. 4. 5. 6. 7. Sodium Potassium Chloride Bicarbonate BUN SCr Glucose 8. Calcium 9. Albumin 10. Total protein 11. Bilirubin 12. Alkaline phosphatase (ALP) 13. Alanine transaminase (ALT) 14. Aspartate aminotransferase (AST) Basic Metabolic Panel (BMP) Intravenous (IV) Fluids • Crystalloids • Solutions of small molecules/electrolytes in water • Sodium chloride (NaCl) a.k.a “normal saline (NS)” • Dextrose aka D5%, D10% • Lactated ringers • Distribute into tissues (multiple compartments) • Colloids • Dispersions of large organic molecules • Proteins (albumin) • Complex polysaccharides (dextrans, starches) • Remain in the intravascular space (generally) Common Fluids: • • • • Which is isotonic? What does that mean? Which is hypotonic? What does that mean? Which is hypertonic? What does that mean? What is in Lactated Ringers? Why does this matter? Fluid Dextrose (g/L) Electrolytes (mEq/L) Tonicity Free water (mL/L) D5W (5% dextrose in water) 50 Na: 0 Cl: 0 Hypotonic 1000 mL 0.45% NaCl (½ normal saline) 0 Na: 77 Cl: 77 Hypotonic 500 mL 0.9% NaCl (normal saline) 0 Na: 154 Cl: 154 Isotonic 0 mL Lactated Ringer’s (LR) 0 Na: 130 Cl: 109 K: 4 Ca: 3 Lactate: 28 Isotonic 0 mL 3% NaCl (hypertonic saline) 0 Na: 513 Hypertonic -2331 mL Cl: 513 HOW DO YOU DETERMINE HOW MUCH FLUID TO GIVE? Maintenance Fluid Requirements • Several formulas exist for calculating maintenance fluid requirements • For ILE-I: • 30-35 mL/kg/day fluid required for “maintenance” • 70 kg patient • 30 mL/kg/day x70 kg = 2100 mL/day • 2100 mL/day divided over 24 hours = 88 mL/hour • ROUND: 90 mL/hour When might a patient need LESS fluid? When might a patient need MORE fluid? Assessing Fluid Status • Patient specific characteristics • Patient history • Current medications • Objective data • • • • Weight Intake/output Physical exam Laboratory values Physical Exam: Blood pressure Mucous membranes Skin turgor Cardiopulmonary Laboratory Values: Electrolytes Serum osmolality Glucose Protein Lipids Urine osmolality Assessing Fluid Status • Clinical signs and symptoms of dehydration • • • • Dry mucous membranes Poor skin turgor Orthostatic hypotension Tachycardia • Fractional excretion of sodium (FENa) • BUN:SCr ratio • Later in the presentation Assessment of Edema • Clinical signs and symptoms of fluid overload • Edema Sodium + (Na ) • Sodium is the major regulating factor for body fluid balance • Most abundant cation in the extracellular fluid • Hold water inside the cell • Na+-K+-ATPase pumps regulate cell volume • Kidneys primarily regulate sodium and water volume REMEMBER: water follows sodium Sodium must always be assessed in combination with volume (fluid) status! Normal range: 135 to 145 mEq/L (135 to 145 mmol/L) 1. Isotonic Hyponatremia 2. Hypertonic Hyponatremia Hypernatremia Sodium + (Na ) Normal range: 135 to 145 mEq/L (135 to 145 mmol/L) 3. Hypovolemic Hypotonic Hyponatremia 4. Isovolemic Hypotonic Hyponatremia 5. Hypervolemic Hypotonic Hyponatremia Hyponatremia • Agitation • Anorexia • Apathy Signs & Symptoms Hypernatremia & Hyponatremia • Depressed deep tendon reflexes • Disorientation • Headache • Hypothermia • Lethargy • Muscle cramps • Nausea • Seizures • Vomiting Causes of Sodium Imbalance HYPERNATREMIA • GI losses • Diuretics • Renal failure • Diabetes insipidus • Iatrogenic • Sodium-containing infusions HYPONATREMIA • Gastrointestinal (GI) losses • Diuretics • Syndrome of inappropriate antidiuretic hormone secretion (SIADH) • Congestive heart failure (CHF) • Renal failure And lots of other medications that you will learn over the next 4 years. Causes of Sodium Imbalance HYPERNATREMIA • GI losses • Diuretics • Renal failure • Diabetes insipidus • Iatrogenic • Sodium-containing infusions HYPONATREMIA • Gastrointestinal (GI) losses • Diuretics • Syndrome of inappropriate antidiuretic hormone secretion (SIADH) • Congestive heart failure (CHF) • Renal failure Hyponatremia • Serum sodium <135 mEq/L • Step 1: Assess serum osmolality/tonicity! What is serum osmolality? • Estimate of water-solute ratio in vascular fluid • Normal range: 285-295 mOsm/kg Hyponatremia • Serum sodium <135 mEq/L • Step 1: Assess serum osmolality/tonicity! Hyponatremia ASSESS SERUM OSMOLALITY Normal osmolality = ISOTONIC Low osmolality = HYPOTONIC High Osmolality = HYPERTONIC Isotonic Hyponatremia Hypertonic Hyponatremia • Normal serum osmolality • High serum osmolality • Excess proteins or lipids • Hyperlipidemia • Hyperproteinemia • Presence of osmotically active substances in the extracellular fluid • Hyperglycemia • Hypertonic sodium-free solutions (mannitol) • Pseudohyponatremia • Pseudohyponatremia Calculate corrected sodium. Isotonic Hyponatremia (Pseudohyponatremia) Hyponatremia • Step 2: Assess volume status! HYPOTONIC Hyponatremia ASSESS VOLUME STATUS Hypovolemic Hypovolemic Hypotonic Hyponatremia Isovolemic/ Euvolemic Isovolemic Hypotonic Hyponatremia Hypervolemic Hypervolemic Hypotonic Hyponatremia Hypovolemic Hypotonic Hyponatremia Isovolemic/Euvolemic Hypotonic Hyponatremia Hypervolemic Hypotonic Hyponatremia • Reduction in Na+ > reduction in total body water (TBW) • No change in Na+; increase in TBW • Depletion of extracellular fluid (dehydration) • Common Causes: • Vomiting • Diarrhea – Loss of Na+ in the GI tract • Diuretics • Addison’s disease • Increase in water with no change • Fluid retention in Na+ • Chronic heart failure • Increased secretion of antidiuretic • Liver failure hormone (ADH) • Renal failure • Psychogenic polydipsia • SIADH (syndrome of inappropriate secretion of ADH) • Increase in TBW > increase in Na+ SIADH Drug-Induced • Acetaminophen • ACE inhibitors • Anti-epileptic agents (barbiturates, • • • • • Monoamine oxidase inhibitors • carbamazepine, lamotrigine, valproic acid) • Anti-infectives (linezolid, moxifloxacin) • AVP analogs (desmopressin, terlipressin, • oxytocin, vasopressin) • Bromocriptine • Cytotoxic agents (carboplatin, cisplatin, • ifosfamide, melphalan, methotrexate, vinca • alkaloids) • Chlorpropamide • Duloxetine • • • • Haloperidol • MDMA (ecstasy) Non Drug-Induced Nicotine NSAIDs Opioids Phenothiazines Proton pump inhibitors Risperidone SSRIs Thioridazine Thiothixene Tolbutamide Tricyclic antidepressants Venlafaxine • Malignancy (lung, pancreatic, • • • • • duodenal) CNS (trauma, tumor, meningitis, hemorrhage, stroke) Pulmonary (pneumonia, ARDS, TB) Postoperative state Nausea Anxiety Am J Health-Syst Pharm. 2005; 62:1663-82. Causes of Sodium Imbalance HYPERNATREMIA • GI losses • Diuretics • Renal failure • Diabetes insipidus • Iatrogenic • Sodium-containing infusions HYPONATREMIA • Gastrointestinal (GI) losses • Diuretics • Syndrome of inappropriate antidiuretic hormone secretion (SIADH) • Congestive heart failure (CHF) • Renal failure Hypernatremia • Serum sodium > 145 mEq/L • Universal increase in serum osmolality • Step 1 of 1: Assess volume status Hypovolemic Hypernatremia Isovolemic/Euvolemic Hypernatremia Hypervolemic Hypernatremia ↓ TBW ↓ TBW ↑ TBW ↓ Na+ ⇋ Na+ ↑ Na+ No change in Na+ Loss of TBW Increase in Na+ > TBW increase TBW loss > Na+ loss Hypovolemic Hypernatremia TBW loss > Na+ loss • Most common • Causes: • Severe diarrhea • Profuse sweating Isovolemic/Euvolemic Hypernatremia Hypervolemic Hypernatremia No change in Na+ Loss of TBW Increase in Na+ > TBW increase • Causes: • Increased insensible water loss (fever, burns) • Diabetes insipidus • Causes: • Increased administration of Na+ (hypertonic solution) • Hyperaldosteronism Potassiu m + (K ) • Normal Range: 3.8 – 5.0 mEq/L Why is the normal range for K+ so much different than Na+? Hyperkalemia • Primary cation in the intracellular space • 98% in intracellular space • Physiologic role ▫ ▫ ▫ ▫ ▫ Regulation of muscle and nerve excitability Hypokalemia Regulation of intracellular volume Protein synthesis Enzymatic reactions Carbohydrate metabolism [Na+-K+-ATPase pump] + [plasma K+ concentration] • Key in regulating K+ balance • Transports out of the cell • Transports K+ into the cell Na+ (3:2 ratio) • Magnesium is cofactor in pump → • Hypomagnesemia = refractory hypokalemia Potassium & the Cardiovascular System • Primary concern when a potassium imbalance exists • Hyper- & hypokalemia • Cardiac muscles rely on potassium for muscle contraction and nerve conduction Potassium & the Kidneys • Potassium balance is the goal • Kidney responsible for potassium control and elimination • Freely filtered • Almost completely reabsorbed before reaching the collecting tubules • ~10% secreted into the urine at distal and collecting tubules • Slow to correct K+ imbalances Potassium & the Distal Tubule • K+ secreted into tubule, Na+ reabsorbed • Aldosterone increases K+ secretion into the urine • Diuretic-induced hypokalemia: • Na+ and fluid in the distal tubule can cause K+ secretion/elimination • Negatively charged anions can attract the positively charged K+ • Dehydration – If intracellular K+ is high, K+ secreted into the urine Intracellular Shifting of Potassium • Faster adjustments in K+ homeostasis • K+ shift intracellular will result in a reduction in serum K+ concentrations • Apparent deficit • Acid base homeostasis (LATER) • Other common causes: • Insulin • Stimulation of B2 receptors Hyperkalemia Potassiu m + (K ) Hypokalemia Hypokalemia – Signs & Symptoms • Cardiac arrhythmias – EKG changes • Skeletal muscle weakness • Decrease in smooth muscle function • Constipation • Urinary retention • Cramps • Decreased reflexes • Paralysis Hypokalemia • Is it a true or apparent deficit? • Apparent Deficit (intracellular shift) • True Deficit • Decreased Intake • Poor Intake - (Alcoholism, anorexia, bulimia) • K+ free IV fluids • Increased Output • GI Losses – vomiting, diarrhea, laxative abuse • Renal Losses – diuretics • Aldosterone Hyperkalemia – Signs & Symptoms • Arrhythmias • EKG changes (peaked T waves) • Cardiac arrest • Weakness • Cramping • Paralysis Hyperkalemia • True or apparent potassium imbalance • True K+ excess • • • • Renal dysfunction Increased intake (salt substitutes, K+ supplements, etc) Decreased aldosterone secretion (Addison’s) Increased release of intracellular K+ into bloodstream • • • • Hemolysis Rhabdomyolysis Tumor lysis Muscle crush injury • Medications What are possible treatments? Am J Health-Syst Pharm. 2005; 62:1663-82. Antagonism of membrane actions of potassium Calcium Drive extracellular potassium into the cells Insulin and glucose Sodium bicarbonate, primarily if metabolic acidosis Beta-2-adrenergic agonists Removal of potassium from the body Loop or thiazide diuretics Cation exchange resin Dialysis • Normal values: 1.7 – 2.4 mg/dL • Distribution: Magnesium 2+ (Mg ) • ~50% in bone • Intracellular • Major role in enzymatic reactions • Cofactor in Na+/K+ ATPase pump • Absorption affected by dietary intake, calcium, vitamin D, parathyroid hormone (PTH) Magnesium • 1/3 eliminated renally and 2/3 through the GI tract • Unbound magnesium freely filtered at glomerulus • 97% reabsorbed • Reabsorption occurs through • Ascending loop of Henle (~60%) • Proximal tubule (~30%) • Distal tubule (~7%) • Factors affecting calcium homeostasis can also affect magnesium Hypomagnesemia • Causes • Renal wasting, GI loss, alcohol abuse, malabsorption • Medications (loop diuretics) • Refeeding syndrome • Signs/symptoms • • • • CNS Weakness EKG changes Low K+ (even after repletion) WHY? Hypermagnesemia • Signs/symptoms: • • • • • • • Nonspecific Fatigue Drowsiness Hypotension Decreased reflexes Arrythmia Cardiac arrest • Rare and rarely symptomatic • Causes • Renal dysfunction • Overreplacement • Normal range: 96 – 106 mEq/L Chloride • Most abundant extracellular anion Hyperchloremia (Cl ) • Low intracellular concentration • Primarily regulated by renal proximal tubules • Exchanged for bicarbonate ions • Passively follows Na+ and water throughout the rest of the nephron Hypochloremia • Influenced by extracellular fluid balance and acid-base balance Chloride • Values primarily used to identify fluid Hyperchloremia balance and acid-base abnormalities (Cl ) • Hyperchloremia – NaCl infusion • Hypochloremia – dehydration, vomiting, Hypochloremia loss of gastric fluid Bicarbonate (HCO3-) • Normal range: 22 - 30 mEq/L • Used to assess acid-base balance • Used with pH and other labs (arterial blood gas) if available • Increased = alkalosis • Decreased = acidosis Blood Urea Nitrogen BUN “Bee – You - En” Blood Urea Nitrogen (BUN) • Normal range: 8 – 23 mg/dL • Concentration of nitrogen (as urea) in the serum • Depends on urea production (liver), glomerular filtration, and tubular reabsorption • Used to monitor hydration, renal function, protein tolerance • Increased BUN: • • • • Renal failure GI bleed High dose steroids Medication adverse effect Blood Urea Nitrogen (BUN) • BUN:SCr ratio • Used to assess acute kidney injury • Volume depletion – both SCr and BUN elevated • BUN:SCr ratio > 20 indicates dehydration Calcium (Ca2+) • Normal range: 8.6 – 10.2 mg/dL • Most prevalent cation – 99% found in teeth • Maintains cell integrity, neuromuscular activity, regulates endocrine secretory activities, bone metabolism • Serum concentrations under control of parathyroid hormone (PTH), vitamin D, and calcitonin • Must correct serum levels for low albumin Hypercalcemia • Causes • • • • Hyperparathyroidism Cancer with bone metastases Toxic levels of Vitamin D or A Thiazides • Causes: • Vitamin D deficiency • Hyperphosphatemia • Medications – bisphosphonates Hypocalcemia Hypercalcemia • • • • • • • • • • Fatigue Weakness Anorexia Depression Anxiety Cognitive dysfunction Vague abdominal pain Constipation Renal symptoms (polyuria, polydipsia, nocturia) Acute pancreatitis (rare) Hypocalcemia Acute: • Tetany • Paresthesia • Muscle cramps • Laryngeal spasms Chronic: • Depression • Anxiety • Memory loss • Confusion • Normal range: 2.3 - 4.7 Phosphorus (PO43-) Phosphate • Major intracellular anion • Mainly found in bones and soft tissues • Intracellular metabolism of proteins, lipids and carbohydrates • • • • Major component of phospholipid membranes Glycolysis Maintains pH Formation of ATP • Intestinal absorption decreased in presence of aluminum & calcium • Eliminated renally • Filtered at glomerulus, reabsorbed at proximal tubule Hypophosphatemia • Signs/symptoms • CNS – Confusion, ataxia • Neuromuscular – weakness, myalgia • Cardiopulmonary – Cardiac and respiratory failure • Causes • Intracellular shifting (insulin) • Refeeding syndrome • Increased renal excretion • Decreased intake (or decrease in Vit D intake) • Alcoholism, malnutrition • Acid-base • Medications that bind phosphate (Calcium/Aluminum) • Fluid and electrolyte abnormalities that occur with the reintroduction of carbohydrates after periods of starvation Refeeding Syndrome • During starvation, the body derives energy from ketone production from free fatty acid oxidation • When carbohydrates are reintroduced, a sudden shift back to glucose as the main fuel source creates a high demand for phosphorylated ATP • Increased cellular reuptake of electrolytes • Hypophosphatemia • Intracellular shift of potassium and magnesium Hyperphosphatemia • Signs/symptoms • • • • Nausea, vomiting Dehydration Neuromuscular irritability Complications • Soft tissue and vascular calcification • Renal osteodystrophy • Causes • Renal dysfunction – Most common • Extracellular shift • Increased intake Why are all of these given with meals? Am J Health-Syst Pharm. 2005; 62:1663-82. Hemolyzed Samples • Occurs due to • • • • • Results in false elevation in Needle too small Tourniquet too tight Specimen stands too long Specimen mishandling • Potassium • Phosphorous Hemolyzed sample = REPEAT (or any strange/questionable result) Why? Integrated Learning Experience-I: Fall 2022 Fluids & Electrolytes Courtney Watts Alexander, Pharm.D., BCPS, BCOP Assistant Professor, Clinical Pharmacogenomics Department of Pharmacy Practice, AUHCOP Email: [email protected] 202363