Energy requirement calculation
Traditionally , a patient ' s basal energy requirement ( BER ) was calculated by multiplying the RER by an illness factor to determine its caloric requirements during hospitalisation and recovery [ 17 , 32 ] . This has since been disputed and it is now acceptable to use the RER as the target for nutritional provision [ 30 , 33 ] . When calculating the RER , the exponential formula is the most accurate , as it considers both the bodyweight and the skin surface within the calculation [ 33 , 34 ] :
RER ( kcal / day ) = 70 × ( bodyweight in kg ) 0 . 75
In the human and veterinary fields , adequate nutritional provision can reduce hospitalisation times , the risk of bacterial translocation and sepsis , and compromise of organ function . This is particularly important in the 14 days immediately following injury , illness or trauma [ 33 ] .
Patients that are inappetent can be tempted to eat in a variety of ways , including using a familiar type of food bowl , warming the food to increase olfactory stimuli , or feeding particularly smelly foods to those with a poor sense of smell or nasal discharge . Hand-feeding increases social interaction ( Figure 2 ) and providing privacy can be helpful for more nervous patients .
In severe or chronic cases of inappetence , the VS may prescribe medications to encourage appetence , but the contraindications and route of administration / delivery should be considered [ 35 ] . If extended inappetence occurs , naso-oesophageal tubes can be placed in the conscious patient , or , in cases where oral nutrition is unsuitable , an oesophagostomy or gastrostomy tube may be appropriate [ 6 ] .
Nutrition should follow the restoration of fluid volume and the correction of electrolyte and acid – base levels via fluid therapy [ 35 ] . While haemodynamic stability should always be the priority , early nutritional support should aim to meet the patient ' s RER within 48 – 72 hours with a gradually increasing nutritional plan , depending on the level and duration of inappetence [ 30 ] .
The food source provided post starvation should be highly digestible , low residue , low fat and low fibre [ 16 ] . Due to the additional risk of refeeding syndrome , a feeding plan should be implemented that aims to provide 26 – 34 % of the RER on day 1 , 50 – 66 % on day 2 , and the patient ' s full RER on day 3 or 4 [ 36 ] . In cats , depending on the period of fasting , feeding should be initiated at 21 % RER and slowly increased by 4 – 10 % daily , depending on the clinical response [ 34 ] . However , other authors suggest that a slower increase , starting at 10 % RER , is recommended during extended periods [ 37 ] .
If assisted feeding has been provided , this should be withdrawn gradually , to allow the necessary gastrointestinal and metabolic adjustments , once the patient is taking in 85 % of its RER voluntarily [ 33 ] . Even in gastrointestinal surgery cases , post-anaesthetic patients are now encouraged to eat as soon as possible to encourage intestinal motility [ 29 ] . In cases of diarrhoea , feeding rather than starving these patients should be encouraged , with a low-fat , highly digestible diet with balanced electrolytes [ 16 ] .
Disruption in the allocation of nutrients for cell renewal and the potential disruption of the commensal gut microbiota may be caused by periods of starvation , antibiotic use or intestinal inflammation , which can influence other organ systems . Multiple organ failure can occur in humans due to bacterial and endotoxin translocation [ 38 ] . There may also be changes in behaviour , stress levels and the nervous system [ 39 ] .
Figure 2 . Hand-feeding can tempt some inappetent patients and increases social interaction .
Parenteral nutrition
Enteral nutrition ( delivered via the gut ) is preferable to parenteral nutrition ( delivered intravenously ) as it reduces the duration of hospitalisation for both human and veterinary patients . Enteral nutrition preserves gastrointestinal function , intestinal permeability and microbial diversity [ 19 ] and prevents villous atrophy [ 18 ] . Prolonged starvation causes enterocyte damage , increasing the risk of intestinal epithelium breakdown and subsequent bacterial translocation [ 6 ] .
Peripheral parenteral nutrition has been associated with lower mortality rates and reduced weight loss , particularly when 100 % RER is provided . However , there is evidence of a lower frequency of metabolic , septic and phlebitis complications when using a nutrition plan that incorporates a 40 – 50 % RER parenteral nutrition treatment [ 19 ] .
42 Veterinary Nursing Journal