Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ Fluid Homeostasis +++ Pathophysiology ++Figure 18-1.Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt)Physiological control of ECF volume & tonicity. ++ Maintain intravascular volume to facilitate tissue perfusion & oxygenation; maintain osmotic equilibrium → tonicity 275–290mOsmol/kg H2O; intracellular = extracellular tonicityDistribution of total body water (TBW): % body weight varies with age Adult ♂ = 50–60%; adult ♀ = 45–55% (↓ with age); TBW = 0.5 × weight (kg) ♀; 0.6 × weight (kg) ♂Intracellular compartment fluid (ICF) = 2/3 of TBWExtracellular compartment fluid (ECF) = 1/3 of TBW; interstitial fluid = ¾ ECF ∼25% of TBW; intravascular fluid = ¼ ECF ∼8% of TBWElectrolyte composition of fluid compartments ECF: Na+, Cl−, HCO3−, albumin → Na+ primary determinant of extracellular osmolality albumin provides oncotic pressure to retain intravascular volumeICF: K+, Mg++, PO4− → K+ primary determinant of intracellular osmolality; physiologic control of water & sodium homeostasis ++Table Graphic Jump LocationTable 18-1 Composition & Clinical Use of Common IV FluidsView Table|Favorite Table|Download (.pdf)Table 18-1 Composition & Clinical Use of Common IV FluidsFluidOsmolalityElectrolytesIndicationsPrecautionsD5WHypotonicNoneFluid maintenance; euvolemiaImpaired glucose control in DM0.45% NaCl (½ NS)HypotonicNa+ 77mEq/LCl− 77mEq/LFluid maintenance; euvolemiaHyponatremia with long-term use; ↑ risk IV infiltration vs isotonic0.9% NaCl (NS)IsotonicNa+ 154mEq/LCl− 154mEq/LFluid replacement; hypovolemia, shockMonitor for fluid overload; hyperchloremic metabolic acidosis with rapid ↑ volumeLactated Ringer's (LR)IsotonicNa+ 130mEq/LCl− 109mEq/LLactate 28mEq/LK+ 4mEq/LCa++ 3mEq/LFluid replacement; hypovolemiaLactate converted to bicarb (liver) → alkalosis; lactate may accumulate in cirrhosis → lactic acidosis3% NaClHypertonicNa+ 513mEq/LCl− 513mEq/LSevere symptomatic hyponatremiaOsmotic demyelination syndrome with too-rapid correction +++ Hyponatremia +++ Pathophysiology ++ Excess free water relative to Na+ in ECF; absolute levels of ECF water & Na+ may be ↑, ↓, or normal depending on etiologyPathophysiology varies by etiology; assess measured or calculated serum osmolality → POsm = 2[Na+] + [BUN]/2.8 + [Glucose]/18; ECF volume status; measured urine [Na+] &/or measured urine osmolality ↑ urine [Na+] (>20mEq/L) implicates the kidney as etiologic site (innapropriate Na+ excretion in hyponatremia); ↓ urine [Na+] indicates an appropriate renal response to extrarenal causeSymptoms result from cerebral edema; severity of edema depends on rate & extent of Na+ ↓ Rapid ↓ (<48h) or large ↓, brain tissue remains hypertonic relative to plasma → draws water from ECF; sx of acute cerebral edema → severe HA, stupor, obtundation, coma, seizures; milder cases → confusion, dizziness, nausea, lethargyGradual ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessPharmacy 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessPharmacy Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options