Intravenous Fluids¶
Chandler Montgomery
Indications for intravenous fluid¶
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Restoration or maintenance of tissue perfusion
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Correction of electrolyte abnormalities
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Nutritional supplementation in those without reliable enteric access
Categorized into crystalloids and colloids¶
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Crystalloid = water + electrolytes
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Colloid = water + proteins/large molecules
Terms¶
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Osmolarity: osmoles of solute per L of solution
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Tonicity: ability to induce movement of water across a membrane
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Buffer: anions such as lactate, acetate, gluconate which are metabolized to bicarbonate in vivo with the goal of sustaining normal plasma pH
Crystalloids¶
- Isotonic fluids used for volume resuscitation
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After ~ 30 mins, redistribute such that only 25% remains w/in intravascular space
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Balanced solutions (ex: Lactated Ringer’s, Plasma-Lyte)= have electrolytes concentrations similar to plasma
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NS may lead to renal vasoconstriction, AKI, hemodynamic instability, increased mortality
- SMART and SALT-ED: balanced solutions had lower rates of death, new renal replacement therapy, or persistent renal dysfunction compared to NS
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Situations where NS may be preferred:
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Cerebral edema/traumatic brain injury
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Hypovolemic hyponatremia
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Pre-existing hypochloremic metabolic alkalosis (e.g. after vomiting or over diuresis)
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Notes on LR
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The small amount of K in LR (~4 mEq/L) is unlikely to significantly exacerbate hyperkalemia
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Lactate in LR is sodium lactate. No hydrogen ions are being added to plasma
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Common crystalloid solutions:¶
| Fluid | Na | Cl | K | Ca | Mg | Glucose | Buffer | Osmolarity | Tonicity |
|---|---|---|---|---|---|---|---|---|---|
| Plasma | ~140 | ~100 | ~4 | ~2.4 | 1.0 | ~0.85 | Bicarb ~24 | ~290 | NA |
| Normal 0.9% saline | 154 | 154 | 0 | 0 | 0 | 0 | 0 | 308 | Isotonic |
| Lactated Ringer’s | 130 | 109 | 4.0 | 2.7 | 0 | 0 | Lactate 28 | 273 | Isotonic |
Plasma-Lyte/ Normosol |
140 | 98 | 5.0 | 0 | 3.0 | 0 | Gluconate 23 Acetate 27 |
295 | Isotonic |
| D5W + 150 mEq HCO3- | 150 | 0 | 0 | 0 | 0 | 50 | Bicarb 150 | 300 | Isotonic |
| 3% Saline | 513 | 513 | 0 | 0 | 0 | 0 | 0 | 1026 | Hypertonic |
| D5W | 0 | 0 | 0 | 0 | 0 | 50 | 0 | 252 | Hypotonic |
Colloids¶
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Albumin: extracted from human plasma
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5% - Used after plasma exchange
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25% - raises oncotic pressure and restore intravascular volume
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Uses: Post-LVP, diagnosis and treatment of hepatorenal syndrome, SBP (see Hepatology)
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Evidence base for use outside of above indications is poor (SAFE trial)
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Blood Products: Packed RBCs, FFP, cryoprecipitate, etc