Extracellular Dehydration

The extracellular Déshydratation results from an extracellular deficit in ion Sodium, which involves an increased escape of Eau (mainly by the Rein S, but also by the Peau, the Poumon S, etc according to the origin of the disorder) in order to preserve the Osmolalité plasma normal tick (290 plasmatic water mosm/kg with a margin of 5 mosm/kg). It is a frequent situation, which can threaten the vital prognosis (by shock hypovolemic) when it is severe and brutal, in particular in the small child unable to express his thirst and particularly sensitive to a fast dehydration.

Etiology

There exist two big families of causes being able to involve a extracellular Déshydratation: extra-renal sodium losses, with an adapted natriurèse (weak sodium losses in the Urine S in order not to worsen the disorder) and the renal, generally consecutive losses with a renal or systemic disease, with a very high natriurèse (higher than 20 m mole s/jour).

Extra-renal losses

The natriurèse is low (lower than 20 moles/day), generally in an obvious context.

the digestive losses are most frequent, in particular at the Nourrisson and the child: acute Diarrhea, Vomiting S, but also digestive aspiration, constitution of a third sector on digestive Occlusion, puncture of Ascite,
cutaneous Losses: Heat stroke with intense sudation, Fever raised, Burn S extended, bulleuse dermatosis, Mucoviscidose (anomaly of sweat),

Renal losses

extra-renal or systemic Diseases: diabetes (syndrome polyuro-polydipsic), taken excessive of Diurétique S, Disease of Addison (surrénalienne insufficiency)
renal Diseases: intersticielle nephropathy, syndrome of lifting of obstacle, necroses tubular acute.

Dehydration .

Diagnosis

The Soif is the Master symptom: it is necessary to keep in mind that infants and old men do not express it, or do not feel it any more. One finds also a persistent cutaneous fold (dehydration higher than 8% of the body weight), a orthostatic Hypotension (see permanent arterial hypotension), a Tachycardie, a loss of Poids (to be evaluated most precisely possible), the Veine S chin-straps are punts, the knees can be marbled (beginning of collapse), the eyes hollow and are encircled.

Biological examinations, when they are carried out (they are not essential when the cause is simple, a such noninvasive acute diarrhea, and in absence of signs of gravity) show a Hémoconcentration with hyperprotidemy, a rise in the Hématocrite, a rise in the Urée and blood Créatinine. Other examinations can be required according to the supposed origin of dehydration.

Treatment

etiologic , when it is possible: substitute hormonal treatment of a disease of Addison, stop of diuretic, antipyretic insulin treatment of the diabetic, treatment, etc

symptomatic , always: oral rehydration in the absence of signs of gravity or vomiting by salted bubbles associated with Fruit juice (because the intestinal absorption of sodium is coupled with that of the Glucose) or perfusion of an aqueous solution glucose + NaCl if not. In the event of shock hypovolemic, perfusion of macromolecules, assistance by Catecholamine S.

The losses must be corrected of 24 hours, with half of the liquids passed in 6 hours.

The monitoring is fundamental: Pulse, blood Pressure, urines (diuresis, natriurèse, uraemia, creatininemy), cranial perimeter in the child, weight.

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