Nutritional support basics for hospitalized patients

(adobestock.com/Alyona)Providing nutrition to critically ill patients is paramount as these patients are in a catabolic state. Anorexia, shock and sepsis all can contribute to malnourishment and require nutritional support to adequately fuel the body to respond to this crisis. Although nutrition is not without any complications, the benefits of providing nutritional support far outweigh and possible side effects, when implemented in a safe and protocol-based manner.

1. Provide nutrition earlier rather than later.

Research in human medicine shows us that the earlier nutritional therapy can be started, the more beneficial the effects such as earlier discharge, reduced in-hospital complications and improved wound healing.1 Delayed nutrition has been associated with negative effects such as increased nosocomial complications, lengthier hospital stays and even whether the patient survives. A 2012 veterinary study of dogs with septic peritonitis found a 1.6 day decrease in hospitalization stay when nutritional interventions were employed.2 Nutritional support was instituted within 24 hours in that study. Current recommendations for acute pancreatitis suggest starting nutritional therapy within 48 hours of admission or immediately if there has been five or more days of anorexia.

2. Calculate nutritional requirements accurately.

Several equations and illness factor multiples have been proposed over the years for calculating the caloric needs of small animals. No specific equation for critically ill small animals exists, but the generally accepted convention suggests to use the Kleiber equation3:

Resting energy rate (RER) = body weight (kg)0.75 x 70

This has been shown to best estimate caloric requirements in critically ill animals.3 In years past, illness factors were used to multiply the RER result by some factor, increasing the daily calories to be administered. These have been shown to be not necessary and may even, in some circumstances, be detrimental and so are no longer required.3 If patients have been anorectic more than three consecutive days, starting with one-third of the RER and ramping up over a few days is also suggested to prevent overfeeding and metabolic consequences of critical illness-related insulin resistance, which can lead to hyperglycemia and hypophosphatemia, among other consequences.

An example: If you have a 22-kg dog who has been anorectic for four days, you would administer 220.75 x 70 = 711 kcal/day base. You would start day 1 as one-third of this, so 235 kcal or so, then double on day 2 to 470 and finally end up at full RER (711 kcal) on day 3.

3. Provide nutrition enterally (if possible).

Enteral nutrition, through the gut, is generally accepted as preferable whenever possible to intravenous nutritional interventions (termed parenteral nutrition). Human studies have shown reductions in in-hospital infections, hospital stay and mortality when enteral nutrition is used, over parenteral nutrition.3 Practically, providing parenteral nutrition in a veterinary hospital requires purchasing specialized intravenous solutions and placing aseptic catheters (central venous catheters if providing total parenteral nutrition), which may be impractical for the smaller facility. Enteral nutrition, on the other hand requires inexpensive feeding tubes, a blender and liquid diets that have long shelf lives and are easily available.

4. Pick an appropriate diet, not the “right” diet.

Many veterinary professionals ponder about the “right” diet for feeding critically ill patients. Generally, these patients need a high-calorie, high-caloric-density diet to provide enough calories in the smallest volume possible. Pancreatitis, for example, is highly debated as to the fat content, but in actuality the connection between fat and pancreatitis is not clearly established. Since there are many “critical care” diets (Hill's A/D, Royal Canin Recovery, Iams Maximum Calorie) the only choice is typically which vendor to use and whether the diet needs to be entirely liquid or can be blended with water to create a thinner consistency. Calculation of the kcal requirement can be somewhat daunting but involves figuring out how many kcal are present in a can, cup or ounce and then dividing by the volume of that container. That will provide the kcal/ml and can be used to finish the volume calculation.

An example: Hill's A/D contains 183 kcal in a 5.5-oz can and 5.5 oz is approximately 156 g. A solid gram is approximately equal to 1 liquid ml. So the caloric density is 183 kcal/156 ml or 1.17 kcal/ml. For our example above, on day 1 the patient requires 235 kcal or about 200 ml of Hill's A/D.

5. Use a tube for anorectic patients.

Oral enteral nutrition, fed as free-feeding, can be useful in providing enteral nutrition. However, anorectic patients require a feeding tube to provide effective and accurate caloric delivery. Nasogastric tubes are easily placed and maintained in both dogs and cats. There are other endoscopic/surgical options that are beyond the scope of this article (gastrostomy, PEG tubes). In most practices, a nasogastric or nasoesophageal option is easily placed by veterinary assistants and technicians, easily maintained, and can provide a majority of liquid diets. Larger-bore tubes in larger animals may facilitate blended soft wet diets, but smaller-gauge tubes may require the use of a fully liquid diet such as Zoetis Clinicare, Nestle Vivonex or Virbac Rebound.

References

1. Kathrani A. Nutritional support in the intensive care unit. In Pract 2016;38:18-24.

2. Liu DT, Brown DC, Silverstein DC. Early nutritional support is associated with decreased length of hospitalization in dogs with septic peritonitis: A retrospective study of 45 cases (2000–2009). J Vet Emerg Crit Care 2012;22:453-459.

3. Jensen KB, Chan DL (2014), Nutritional management of acute pancreatitis in dogs and cats. J Vet Emerg Crit Care 2014;24:240-250.

David Liss, MS, RVT, VTS, CVPM, PHR, is a veterinary subject matter expert in the areas of veterinary critical care nursing and practice management. He holds a master's degree in Biomedical Veterinary Science and has been a veterinary industry professional for over 17 years. He has worked as a technician in emergency medicine, in academia, and currently manages a 24-hour ER/GP hybrid hospital in Los Angeles, Califronia. He enjoys the outdoors and time with his chihuahua, “Brut.”