Tables
| Extent of Dehydration | Mild | Moderate | Severe |
| Weight Loss -- Infants | 5% | 10% | 15% |
| Weight Loss -- Children | 3%- 4% | 6% - 8% | 10% |
| Pulse | Normal | Slightly Increased | Very Increased |
| Blood Pressure | Normal | Normal to orthostatic, >10mm Hg change | Orthostatic to shock |
| Behavior | Normal | Irritable, more thirsty | Hyperirritable to lethargic |
| Thirst | Slight | Moderate | Intense |
| Mucous Membranes* | Normal | Dry | Parched |
| Tears | Present | Decreased | Absent, sunken eyes |
| Anterior Fontanelle | Normal | Normal to sunken | Sunken |
| External Jugular Vein | Visible when supine | Not visible except w/ supraclavicular pressure | Not visible even with supraclavicular pressure |
| Skin* - (Less useful in children > 2 Y) | Capillary refill >2 sec | Slowed capillary refill, 2-4 sec (decreased turgor) | Very delayed capillary refill (>4 sec) and tenting; skin cool, acrocyanotic, or mottled * |
| Urine Specific Gravity | >1.020 | > 1.020; oliguria | Oliguria or anuria |
| *These signs are less prominent in patients who have hypernatremia | |||
| Body Fluid Physiology |
| In the ECF, Na and Cl constitute 90% or more
of the effective solutes. Serum Na concentration defines
the relative amount of sodium and water in plasma; the
maintenance of a normal Na concentration, thus,
contributes to regulation of the volume of body fluids.
The size of the ECF and ICF compartments dependson the
amount of water within each; the distribution of water
depends on their osmolality. The osmolality of a solution
is a function of the number of solute particles or
osmoles per unit volume. In a given patient, the
effective osmolality may be calculated as follows, using
the values of 2.8 and 18 to convert values of blood urea
nitrogen (BUN) and glucose, respectively, to mOsm/L. Osmolality = 2[Na in mEq/L] + [BUN in mg/dL] / 2.8 + [Glucose in mg/dL] / 18 Normal serum osmolality (265 to 285 mOsm/L) is maintained by kidney function, which dilutes or concentrates urine. This is accomplished by a variety of mechanisms involving glomerular filtration, arterial pressure, blood flow, physical factors in the kidneys, the sympathetic nervous system, and hormones such as aldosterone, atrial natriuretic factor, vasopressin, and dopamine. These systems comverge to control water and electrolyte balance through glomerular ultrafiltration of the plasma followed by changes in the electrolyte content of this ultrafiltrate by tubular reabsorption and secretion. These mechanisms,together with thirst, control both plasma osmolality and plasma volume.(1) |
| return |
| Solution | Osmolality mOsm/L |
Glucose mmol/L |
Na mEq/L |
Cl mEq/L |
HCO3 mEq/L |
K mEq/L |
| Intravenous solutions | ||||||
| Ringer's | 280 | ... | 130 | 110 | 25 | 4 |
| 0.9% Saline | 308 | ... | 154 | 154 | ... | ... |
| D5 -- 0.45% Saline | 454 | 300 | 77 | 77 | ... | ... |
| D5 -- 0.22% Saline | 377 | 300 | 38 | 38 | ... | ... |
| Butler's | 450 | 300 | 40 | 40 | 20 | 35 |
| IDEAL* | 460 | 300 | 60 | 50 | 30 | 20 |
| [*Not commercially available] | ||||||
| Homemade Solution | 300 | 58 | 48 | 30 | 20 | |
| D5 0.22% Saline with K Acetate 10 mEq/L; KCl 10 mEq/L; NaHCO3 20 mEq/L added | ||||||
| Oral Solution | ||||||
| WHO - ORS# | 330 | 110 | 90 | 80 | 30 | 20 |
| Rehydralyte# | 140 | 75 | 65 | 30 | 20 | |
| Low-Na ORS | 270 | 110 | 60 | 50 | 30 | 20 |
| Pedialyte | 270 | 140 | 45 | 35 | 30 | 20 |
| [# Higher Na solutions are successful as long as they are supplemented with oral water ad libitum] | ||||||
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