Fluids and Electrolytes Introduction ions

intro to fluids and electrolytes

1. Fluids and Electrolytes Stas Bushik PGY1 6/10/19

2. Electrolytes Sodium: key role in muscle and nerve function. Mainly extracellular. Hyponatremia: sluggishness, confusion, if severe can have seizures and/or muscle contractures Hypernatremia: thirst, if severe can lead to confusion, muscle twitching, seizures, coma Potassium: also plays a key role in muscular and nervous function. Mainly intracellular. Hypokalemia: muscle weakness, paralysis, dysrhythmias Hyperkalemia: dysrhythmias Chloride: anion that plays a role in fluid balance (intra and extracellular) Hypochloremia: weakness, fatigue, confusion Hyperchloremia : thirst, confusion Bicarbonate: key role in pH balance. Mainly extracellular Aberrations cause pH shifts

3. Electrolytes Chloride: anion that plays a role in fluid balance (intra and extracellular) Hypochloremia: weakness, fatigue, confusion Hyperchloremia : thirst, confusion Bicarbonate: key role in pH balance. Mainly extracellular Aberrations cause pH shifts Calcium: critical component of many intra and extracellular reactions, such as the coagulation cascade. Mainly found bound to albumin in the blood. Hypocalcemia: muscle spasm, weakness, paresthesias Hypercalcemia: generally asymptomatic, but chronically can lead to nephrolithiasis and calcification

4. Electrolytes Calcium correction: Serum calcium + 0.8 x (4 – serum albumin) = corrected calcium Magnesium: critical cofactor in any reaction powered by ATP, key role in metabolism Hypomangesemia : generally asymptomatic, can affect metabolism. Often associated with hypokalemia Hypermagnesemia : asymptomatic

5. Body Fluid Electrolyte Compositions

6. Fluid Balance

7. Fluids Maintenance fluid : undertaken when patient cannot eat or drink ( eg preop ) in the setting of normal or near normal fluid balance Resuscitative fluid : given when patient has fluid loss for any reason ( eg dehydration from vomiting/diarrhea, blood loss, other fluid loss) Classes of Fluids: Crystalloid: characterized by presence of ions in fluid – normal saline, Ringer’s lactate, plasmalyte , etc. Colloid: characterized by presence of large nonionic molecules such as proteins or carbohydrates – Albumin Blood Products – PRBC, FFP, Cryoprecipitate, etc.

8. Crystalloids

9. Fluid Administration Which fluid to give is decided on a patient-to-patient basis. There is not clear cut right answer which fluid to use, other than when there is a specific indication. Fluid loss due to hemorrhage (trauma): main goal is to maintain organ perfusion, so typically normal saline is given in conjunction with blood products Fluid loss due to GI losses (vomiting, diarrhea): no hard evidence on which fluid is better, but LR and PlasmaLyte have potassium which is lost in GI losses Crystalloid solutions with dextrose often used in pediatrics ( eg D5 ½ NS)

10. Fluid Administration Colloids may be used in patients with malnutrition – low BP in setting of adequate crystalloid administration, can add colloid to increase shift from intracellular to extracellular compartment Hypertonic saline is used in patients with severe hyponatremia with symptoms, such as seizures In diabetic patients on an insulin drip fluid administration usually includes a crystalloid with dextrose, such as D5 ½ NS to prevent large fluctuations in plasma glucose concentrations

11. Fluid Administration Bolus fluid administration Adults: 1L bolus, then re-evaluate Pediatrics: 20cc/kg of crystalloid fluid

12. References Sabistons – Shock, Fluids, Electrolytes Chapter UpToDate – Maintenance Fluid Therapy in Adults