Patho Week 1 Fluid and Electrolytes PDF

Module 1 – Week 1 Module 1 Topics // Fluid and Electrolytes; Acid/Base Balance Part 1: Fluid and Electrolytes A. Fluid Distribution: 60% of body weight is water o Intracellular: 2/3 ▪ Fluids found ___________ the cells o Extracellular: 1/3 ▪ Fluids found ___________...

Module 1 – Week 1 Module 1 Topics // Fluid and Electrolytes; Acid/Base Balance Part 1: Fluid and Electrolytes A. Fluid Distribution: 60% of body weight is water o Intracellular: 2/3 ▪ Fluids found ___________ the cells o Extracellular: 1/3 ▪ Fluids found ___________ the cells Intravascular Interstitial Transcellular B. Fluid Regulation: RAAS system, ADH, ANP/BNP 1. Renin-Angiotensin-Aldosterone System: Overall Net Effect: Increased plasma volume, increased blood pressure, increased vascular tone, and increased cardiac output Key hormones of the RAAS: - Renin: o Released by: - Angiotensin: o Angiotensin 1 + ___________ = Angiotensin 2 - Aldosterone: o Regulates __________ reabsorption o Remember: Wherever salt/ sodium goes, water follows 4 Version: August 2024 2. Anti-Diuretic Hormone (ADH) / Vasopressin: Overall Net Effect: Increased plasma volume, increased blood pressure What does ADH tell the kidneys to do? 3. ANP and BNP: Overall Net Effect: Decreased plasma volume, decreased blood pressure 5 Version: August 2024 C. Edema Fluid Dynamics: A reminder Edema: A condition where fluid leaves the blood vessel and enters the interstitial space Causes of Edema: 1. Due to increased hydrostatic pressure: a. Circle the correct option: Hydrostatic pressure is a pulling / pushing force b. Examples: 2. Due to decreased colloidal osmotic pressure (oncotic pressure): a. Circle the correct option: Osmotic pressures is a pulling / pushing force 6 Version: August 2024  b. Examples: 3. Due to increased vascular permeability: a. Examples: D. Causes of Fluid Volume Imbalance Excessive water loss: SIADH: Syndrome of Inappropriate ADH Definition: Excessive ADH = excessive reabsorption of water Fluid overload → signs and symptoms of SIADH o Elevated blood pressure o Hyponatremia: irritability, confusion, headache, muscle cramps, twitching, pulmonary congestion o Concentrated urine: high specific gravity (dark and concentrated), high urine osmolality o Edema: fluid escapes the blood vessel and enters the tissue o Water intoxication 7 Version: August 2024  DI: Diabetes Insipidus NO ADH = excessive loss of water The absence of ADH results in excessive water loss, leading to the production of large amounts of urine As a result, 2 processes happen: the volume of fluid circulating in the body ________________, while the volume of fluid exiting the body as urine __________________. Therefore, as the plasma volume decreases, the plasma osmolality __________________ and as the urine volume increases, osmolality ______________________. Another test you may see for urine is the specific gravity. Additionally, the concentration of sodium in the blood vessel increases as more water is lost in the urine, leading to __________________________. Hypernatremia results in increased thirst, lethargy, fatigue, confusion, muscle twitching, seizures and coma. E. Electrolytes: Na+ / K+ Sodium (Na+) : 135-145mEq/L Principles: Water follows Sodium Greatest concentration of sodium is in the extracellular fluid (ECF) Key Concept: Sodium regulates fluid volume and movement o Hyponatremia: ▪ Signs and symptoms: ▪ Causes: o Hypernatremia: ▪ Signs and symptoms: ▪ Causes: 8 Version: August 2024  Potassium (K+) : 3.5-5.0mEq/L Principles: Assists in balancing the electrochemical gradient across the plasma membrane Involved in acid-base balance Key Concept: Potassium regulates conduction of cardiac muscle o Hypokalemia: ▪ Delayed repolarization of cardiac muscle due to lack of potassium (LOW & SLOW) ▪ Signs and symptoms: ▪ Causes: o Hyperkalemia: ▪ Sharper T-wave because of K-driven repolarization (TIGHT & CONTRACTED) ▪ Signs and symptoms: ▪ Causes: F. Electrolytes: Ca2+ / P / Mg2+ Calcium (Ca2+) : 9.0-10.5mEq/L Principles: Involved in blood coagulation Assists in neuronal release of neurotransmitters Key Concept: regulates muscle contraction o Hypocalcemia: ▪ Trousseau’s Sign: ▪ Chvostek’s Sign: 9 Version: August 2024  ▪ Signs and Symptoms: ▪ Causes: o Hypercalcemia: ▪ Moans: CNS effects – fatigue, memory loss, psychosis, depression, lethargy ▪ Bones: painful conditions (osteitis fibrosa cystica) ▪ Stones: calcium-based kidney stones ▪ Thrones: nausea, vomiting, abdominal pian ▪ Causes: Phosphate (PO4) : 2.5-4.5mg/dL Principles: Opposite to calcium Increased calcium → decreased phosphate (and vice versa) Important for regulation of bone density and integrity Assists in enzymatic reactions Key Concept: contributes to cell membrane stability o Hypophosphatemia ▪ Signs/ symptoms: ▪ Causes: o Hyperphosphatemia ▪ Signs/ symptoms: ▪ Causes: Magnesium (Mg2+) : 1.3-2.1mEq/L Principles: mainly regulated by renal excretion in association with parathyroid hormone (PTH) and Vitamin D Assists in regulating blood pressure Assists in enzymatic reactions 10 Version: August 2024  Key Concept: acts as a muscle relaxant o Hypermagnesemia ▪ Signs/ symptoms: ▪ Causes: o Hypomagnesemia ▪ Signs/ Symptoms ▪ Causes: Part 2: Acid/Base Balance A. Buffer System a. Serum i. Immediate ii. Bases can combine with acids (form water & CO2) iii. Proteins can combine with H+ iv. K+ can exchange for H+ b. Respiratory i. Minutes to hours ii. CO2 levels are tightly regulated iii. Increased CO2 → ___________________ iv. Decreased CO2 →___________________ c. Renal i. 2-3 day delay ii. Continuous iii. Produce & recycle HCO3- iv. Filter and excrete excess H+ v. Ammonia + H+ = Ammonium B. Respiratory Imbalances: 11 Version: August 2024 C. Metabolic Imbalances: D. Clinical Features of Acid/Base Imbalances: Respiratory: o Normal rate 12-20 breath/min in adults o PaCO2 : low in alkalosis, high in acidosis o PaO2 : low in hypoxia Metabolic: o HCO3-: high in alkalosis, low in acidosis o Anion gap: high in acidosis, low in alkalosis E. Anion Gap: A laboratory test that measures whether electrolytes are imbalanced 12 Version: August 2024  Equation: (Na+ + K+) – (HCO3- + Cl-) High anion gap = acidosis F. ABGs: Normal values pH: 7.35-7.45 PaCO2: 35-45 mmHg (partial pressure of arterial carbon dioxide) HCO3: 22-26 mEq/L (arterial concentration of bicarbonate) Steps to interpreting ABG’s 1. What is the pH? 2. What is the PaCO2? 3. What is the HCO3? 4. Are they normal? (if yes, stop here) 5. Any compensation? (look at the pH) Below, you will find several practice ABG scenarios. The answers to each scenario are contained in the lecture video by Dr. Hill entitled “ABGs”. Please see your week 1 module for the video. Additional ABG practice can be found in the appendix to this outline. 13 Version: August 2024  14 Version: August 2024