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Emergency medicine in a nutshell: Fluid therapy guidelines.

Many seriously ill patients are at least 5-7% dehydrated, so volume replacement, i.e. the supply of fluids, is necessary. First of all, it is necessary to find the underlying disease that affects the amount and type of infusion solutions. Hypoproteinemia/albuminemia, heart disease, hypertension and glaucoma require special treatment. The therapy takes place in different phases:
Phase I: Emergency and shock treatment
Phase II: Rehydration, treatment of the first 24 hours.
Phase III: maintenance therapy after 24 – 36 hours.

Estimation of the degree of dehydration

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The percentage is determined by assessing skin turgor and mucous membranes. Prolonged capillary filling time, weight loss, and poor pulse quality can also be signs of fluid loss. Elderly and cachectic patients as well as patients with cushing’s disease have reduced skin turgor because skin elasticity is reduced. The skin of overweight patients, on the other hand, can easily fade even though there is a lack of liquid.

5% dehydration (mild)
– turgor slightly reduced,
– dried mucous membranes,
– Eyes normally moist and shiny

8% dehydration (moderate)
– turgor moderately reduced,
– dry oral mucosa,
– Conjunctiva without shine

10% dehydration (severe)
– Skin spreads slowly
– sticky oral mucosa
– Conjunctiva sticky, eye heal in the orbit

12% dehydration (very severe)
Further changes.


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In the laboratory, severe changes in the water and electrolyte balance and the resulting incipient organ failure can be read from Hb, TP, Hk, Alb, Glob, BUN, Krea, electrolytes, the acid-base status and the specific gravity of the urine.

After determining the degree of severity, the required infusion volume can be calculated.


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In shock, dogs may receive up to 20 ml/kg bw/h and cats up to 10 ml/kg bw/h. The previously calculated total amount is administered in four portions. The clinical condition can be observed during breaks of 15-20 minutes each. In principle, the administration of liquids is also determined by the serum electrolytes. In practice, however, neither an electrolyte nor a blood gas meter is normally available. If quick help is necessary, it is always better than none at all using the method described – the patient can compensate for smaller electrolyte differences himself if Ringer’s or Ringer’s lactate is given. If he does not stabilize, he can still be referred to an intensive care unit, somewhat more stable than when treatment started.

Lactated Ringer’s solution is found to be very useful in correcting acid-base shifts due to its buffering properties. If there is a volume deficit after major bleeding or serious operations, higher-molecular infusion solutions should be given, e.g. dextran 70 or hydroxyethyl starch. Crystalline solutions leave the bloodstream and, in large quantities, can lead to pulmonary edema. This cannot happen with dextran or HES.

After 6-12 hours, even severe dehydration should recover.

Maintenance therapy

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Ringer’s lactate and physiological saline are not suitable for maintenance therapy. They contain far too little potassium and too much sodium and chloride. Full electrolyte solutions are more suitable here. In maintenance therapy, the energy balance is more important than in the acute phase. Glucose or fructose and later also amino acids should be added. At the same time, a large part of the required liquid and energy can be supplied with oral preparations.