Neonatal emergencies: How to help patients survive the critical period - Veterinary Medicine
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Neonatal emergencies: How to help patients survive the critical period
When a decompensating neonate is presented to your veterinary clinic, make sure you're prepared to take life-saving measures to address hypoxia, hypothermia, hypoglycemia, and dehydration.


VETERINARY MEDICINE


FLUID THERAPY

Consider fluid therapy in neonates experiencing cardiovascular collapse, no matter the cause. Neonates are more prone to dehydration because of immature renal function, increased surface area to mass ratio, and more permeable skin.11 The skin tent test for dehydration assessment is not reliable in neonates because of increased water content and decreased fat content of the skin.11 However, dehydration can be judged most reliably by evaluating the mucous membranes (they should be moist and hyperemic, not tacky or pale) and assessing ability to urinate. If you use a moist cotton swab to stimulate the perineal region of a neonate that has not recently urinated and no urine is produced, the neonate is likely dehydrated.

The fluid rate and route of administration depends on the degree of dehydration, which is determined subjectively by the degree of mucous membrane dryness, urine production, and overall patient status. Fluids should be warmed to 95 to 99 F (35 to 37.2 C)13 before they are given by any route to prevent iatrogenic hypothermia. Possible fluid administration routes include oral, subcutaneous, intraperitoneal, intravenous, and intraosseous.

And keep in mind that a neonate's renal system is immature and incapable of concentrating urine. It is not difficult to fluid-overload a neonate. Weight must be monitored hourly and signs of fluid overload (e.g. increased lung sounds) are cause for reevaluation of the fluid therapy plan.

Oral administration

Oral fluids in the form of a commercial milk replacer or a replacement fluid such as lactated Ringer's solution with added dextrose can be given through a stomach tube only to normothermic, hydrated neonates with normal blood glucose. Oral fluids are a favorable consideration when a neonate is conscious and normothermic but not able to nurse from the dam.

At a core body temperature of < 94 F (34.4 C), bradycardia and gastrointestinal ileus occur,3,12,13,19 and fluids given orally cannot be properly absorbed. In addition to not receiving the nutrition and hydration that the neonate needs, this also places the puppy or kitten at risk for aspirating stomach contents and acquiring bacterial pneumonia or developing sepsis due to gastrointestinal stasis.

To administer oral fluids, measure a 5- to 8-Fr feeding tube from the tip of the nose to the last rib, and mark where it exits the mouth.11 Passing the tube down the left side of the throat will help ensure that the tube is placed in the esophagus rather than the trachea. Puppies and kittens do not develop a gag reflex until about 10 days of age,1 so this cannot be used to assess whether the tube has entered the esophagus. Confirm proper placement of the feeding tube radiographically or by instilling a small amount of saline solution; if the saline exits the neonate's nose, the tube is in the trachea.

When administering milk replacer, remember that the stomach capacity of a neonate is about 50 ml/kg1 and the energy requirement is about 20 to 26 kcal/100 g body weight/day.3 Avoid filling the stomach to capacity to help prevent aspiration pneumonia. Feeding every two to four hours while the neonate is awake is ideal.11 Kink the tube during removal to avoid aspiration pneumonia.

Subcutaneous administration

Subcutaneous fluids are a desirable option if a neonate is only mildly or moderately dehydrated and has normal tissue perfusion. Fluids can be delivered in the interscapular space, as in adults. The maintenance fluid dose can be calculated and given subcutaneously in several divided doses over the day.

Balanced electrolyte solutions such as lactated Ringer's solution and Normosol-R (Hospira) are appropriate for correcting mild dehydration.11 Treat mild hypoglycemia by adding 2.5% dextrose solution to 0.45% sodium chloride solution and administer it subcutaneously (adding dextrose to isotonic fluids will result in fluids being drawn out of the intravascular space).11

Serum can be delivered subcutaneously in neonates that did not nurse for the first 24 hours and have failure of passive transfer. Pooled serum from well-vaccinated adult dogs or cats can be administered subcutaneously at a dose of 22 ml/kg for puppies20,21 and 150 ml/kg for kittens22 to raise serum IgG concentrations. Perform blood typing and crossmatching to prevent neonatal isoerythrolysis, especially in kittens.


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Source: VETERINARY MEDICINE,
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