M. De Scally
Hilton Veterinary Hospital, Hilton, South Africa; Hilton Veterinary Hospital, Howick, South Africa
Introduction
The WSAVA nutrition committee has spent a large amount of effort trying to increase the awareness of nutrition as the fifth vital assessment in all patients.1 Nutrition tools have been published describing standardised nutritional assessments and nutrition planning.1 Despite this, various publications have documented malnutrition in hospitalised patients in small animal veterinary hospitals.2 It is suggested that unless starvation is planned for surgical reasons all hospitalised animals should have their resting energy requirements (RER) calculated, an appropriate diet prescribed and feeding instructions written for them on their hospital chart.1 Actual amount eaten must also be recorded, and if insufficient, an assisted feeding plan must be implemented.1 Importantly, total water intake is also monitored to avoid over or underhydration. In a survey conducted by the WSAVA nutrition committee in 2018 in Clinicians Brief only 4.1% of respondents (98 of 2388) used a systematic nutritional assessment in hospitalised patients. In the same survey only 54.7% of respondents (1339 of 2390) did any form of nutritional assessment as part of the routine assessment of patients’ general health status. These findings are far from ideal, given the benefits of appropriate nutrition, and indicate that a more objective assessment of risk of malnutrition may be necessary in our veterinary hospitals, as has been attempted in human medicine.3,4
Assessing a Critical Care Patient for Risk of Malnutrition
The eight parameters that place critical care patients at risk have been identified and are listed below.5 Each parameter scores a minimum of 0 and a maximum of 3. A total score of ≥6 points is a call to action. Scores vary from 0 to a maximum of 24 points and are assessed daily.
1. Days of hyporexia, as defined by <80% RER intake, is a historical parameter where RER or resting energy requirements are determined using the following equation:6
RER (kcal/day) = 70 x BM (kg)0.75
This parameter is divided into 3 risk levels. RER intake of <80% for less than 3 days scores 1 point towards the NSI, 3–5 days scores 2 points towards the NSI, and >5 days score 3 points towards the NSI. Once a patient has exceeded 5 days of <80% of RER intake they continue to score 3 points until 80% or greater RER intake is met voluntarily, through tube feeding, or a combination of tube feeding and parenteral feeding. At this point the patients scores 0 points towards the NSI for hyporexia indicating an adequate nutritional plan has been implemented or the patient’s appetite has returned. If a patient has begun tube feeding but is still at <80% of RER they will still score 3 points towards their NSI for this parameter and 6 points if any other major risk factor is present forcing a re-evaluation of the nutritional plan each day.
2. Presence of anorexia for 24 hours:
The patient scores 3 points towards the NI for the presence of anorexia if there is a total refusal of food intake for a 24-hour period even if tube feeding or parenteral feeding has been instituted, it is also a historical parameter. If the patient has any voluntary intake of food, they score 0 points towards the NI but still score points according to the presence of hyporexia in parameter 1. It is therefore important to offer patients a small amount of a highly palatable diet appropriate for the patient’s disease just prior to tube feeding each day to assess this parameter.
3. Greater or equal to 10% weight loss from original weight prior to illness:
This parameter is somewhat subject to a recorded previous weight history which if present becomes simple mathematics and if not available is left to subjective assumption, therefore again it is a historical parameter. If a patient is deemed to have lost more than 10% of body weight, they score 3 points towards the NSI until at least 1% weight gain is achieved for 2 consecutive days.
4. Severe vomiting or diarrhoea:
Severe vomiting negates the benefit of most oral or tube feeding with perhaps the exception of a jejunostomy tube; for this reason, every effort is made to control vomiting symptomatically or by treating the underlying disease mechanism causing the vomition, this course of action is assumed for every disease state involving nausea and/or vomition. Several disease states have been shown to benefit from a “feed through the vomiting” approach, or at least an “early return to feeding” approach, such as canine parvoviral gastroenteritis and canine pancreatitis.
Severe vomiting is defined as ≥3 vomiting episodes per day for which the patient will score 3 points towards their NSI and continue to do so until it is resolved as it reduces nutrient intake. Severe diarrhoea can be defined as ≥250 ml watery stool per 10 kg per day, it decreases nutrient absorption, and everything should be done to treat any underlying pathomechanism of this symptom. The presence of severe diarrhoea will add 3 points to the NSI unless this has already been added due to severe vomition.
5. Body condition score 4/9.
Body condition is scored (BCS) according to the WS-AVA nutrition guidelines, it is a clinical parameter. If the patient has a body condition score less than 4/9 they score 3 points towards their NSI until their BCS shows improvement.
6. Muscle condition score ≤2/3.
Similarly, to BCS, muscle condition score (MCS) is scored according to the WSAVA nutrition guidelines, it is a clinical parameter. If the patient has an MCS condition score ≤2/3 they score 3 points towards their NSI until their MCS shows improvement.
7. Hypoalbuminaemia
Hypoalbuminaemia is defined as a serum albumin less than the laboratory reference range for dogs and cats, it is a biochemical test. A patient with hypoalbuminaemia scores 3 points towards their NSI until their albumin starts improving. Albumin is a crude reflection of decreased protein and energy intake in cases with a functional liver.7
8. Length of expected course of illness: low risk <3 days, moderate risk 2–3 days, high risk >3 days or unresolving CRP >30 mg/l.
An accurate diagnosis and knowledge of likely disease progression are essential in determining the expected course of illness. Chronic diseases continue to score 3 points towards their NSI until they are resolved. Unresolvable diseases will continue to score 3 points towards their NSI. This means that patients with unresolvable diseases need only have one other parameter present to be at risk of malnutrition.
An initial or unresolving canine C-reactive protein >30 mg/l is also useful to determine risk of malnutrition. This inflammatory marker can be used to help determine the severity of inflammatory diseases and monitor their progression.8 A CRP of >30 mg/l reflects significant systemic inflammatory levels which could correlate to a higher risk of malnutrition. CRP levels increase within 6 hours of significant systemic inflammation and begin to decrease 24 hours after resolution. The higher the CRP the more severe the systemic inflammatory disease and the more likely that the expected course of illness will persist for more than 3 days.
An increasing CRP is an indication that the underlying disease process is not controlled. CRP will not be raised in chronic inactive diseases such as chronic renal failure and is also not yet available for cats, for this reason it is proposed that CRP is added to the NSI as an alternative to duration of disease in appropriate cases where it is being monitored.
Conclusion
Given our recent WSAVA survey has highlighted the risk of continuing malnutrition in hospitalised animals it is hoped that a better understanding of the parameters that place them at risk will lead to improve attention to their nutritional needs and therefore improve patient care. It is also hoped that by placing objectivity to their assessment a nutrition plan can be monitored for how successful it is.
References
1. Freeman L, Becvarova I, Cave N et al. WSAVA Nutritional Assessment Guidelines. Journal of Small Animal Practice 2011;52:385–396.
2. Heyland DK, Dhaliwal R, Wang M, et al. The prevalence of iatrogenic underfeeding in the nutritionally ‘at risk’ critically ill patients: Results of an international, multicenter, prospective study. Clinical Nutrition. 2015;34:659–666.
3. Brunetto MA, Gomes MOS, Andre MR, et al. Effects of nutritional support on hospital outcome in dogs and cats. Journal of Veterinary Emergency and Critical Care. 2010;20:224–231.
4. Barker JP, Detsky AS, Wesson DE, et al. Nutritional assessment: A comparison of clinical judgement and objective measurements. New England Journal Medicine. 1982;306:969–972.
5. Chan D, Freeman LM. Nutrition in critical illness. Vet Clin North Am Small Anim Pract 2006;36:1225–1241.
6. Chan DL. Nutritional requirements of the critically ill patient. Clinical Techniques in Small Animal Practice 2004;9:1–5.
7. Tiogo G, Ciocchi B et al. Metabolic response to injury and sepsis: Changes in protein metabolism. Nutrition 1997;13:52S–57S.
8. Eckersall PD, Bell R. Acute phase proteins: biomarkers of infection and inflammation in veterinary medicine. Vet J. 2010;185(1):23–27.