The primary goal of nutritional assessment is to identify which patient is at risk for malnutrition. As altered nutritional status is associated with adverse clinical outcomes, it becomes paramount to address the nutritional needs early in the critically ill patient. Although clinical status alone may dictate the need for nutritional intervention, a thorough nutritional assessment consists of evaluating both clinical and biochemical data, including patient history, and a thorough physical exam including body weight and body condition scoring. A baseline nutritional assessment should be followed by serial assessments throughout the course of hospitalization. The veterinary technician is in a crucial position to identify baseline data and ongoing changes in nutritional status, as it is the technician that spends most the time with the patient. Nutritional intervention is crucial to recovery and survival, particularly with the critical patient, and appropriate consideration as to the type and route of nutrition should be given based on the underlying disease process or diagnosis.

Patients At Risk For Malnutrition

Any patient that is anorexic or NPO for three days or longer is a candidate for malnutrition. However, of particular concern for nutritional insufficiencies include patients with increased metabolic stress levels, including surgical patients, sepsis patients, burn victims, trauma patients, head injuries, and patients with respiratory difficulties. The hypermetabolic state these types of patients exhibit results from increased catecholamine releases in order to increase their fuel production. Unfortunately, the increased metabolic rate and subsequent catabolism rapidly exacerbates weakness in patients without nutritional support. Even more serious is the loss of visceral proteins such as serum proteins, immunoglobulins, and leukocytes needed to maintain immunocompetence to fight infection.

Signs and Symptoms of Nutritional Deficiency

Critical illness is associated with increases in metabolism to provide energy for immune responses and healing. Again, this hypermetabolic process is an effort by the body to mobilize its supply of circulating nutrient substrates such as glucose and amino acids. Unfortunately, this mobilization occurs at the expense of body tissue and function at a time when protein synthesis demands are also high. The body becomes reliant on its protein stores to provide gluconeogenesis, as glucose is desperately needed as a fuel source. Consequent loss of protein results in weight loss and alternations in protein homeostasis. Loss of lean body mass is associated with patient morbidity and mortality, and it critical to be able to recognize symptoms of nutritional insufficiency. In the critically ill or injured patient, the hypermetabolic state continues as the body attempts to heal itself. Thus, as a result of the hypermetabolic state, a patient's resting energy expenditure and oxygen demands are increased. Clinical signs of such metabolic events include tachycardia, tachypnea, hyperglycemia, and the eventual net breakdown of skeletal muscle protein and the mobilization of body fat.

Generalized weakness and exercise intolerance are generally the first signs of malnutrition to surface. This weakness reflects the loss skeletal muscle mass from altered protein homestasis. Again, keep in mind that such a patient may have normal to high blood glucose as it is using its protein for fuel as a normal stress response. Protein from all body organs is utilized, which can result in eventual organ dysfunction without nutritional support. It is important to note that the obese or overweight patient can also develop malnutrition in spite of excessive amounts of fat. The overweight patient's nutritional needs may also be overlooked as the signs of muscle weakness and muscle wasting become less obvious. Note that all critically ill patients, regardless of body weight, need the same degree of nutritional assessment and monitoring.

Respiratory function deteriorates as intercostals and diaphragmatic muscles waste, resulting in poor ventilation and consequent hypoxia. Chronic hypoxia results in pneumonia and atelectasis. Increased respiratory efforts and increased respiratory rates require a tremendous amount of energy. Recumbent patients are at the greatest risk of respiratory insufficiency as nutritional uptake is generally poor, with muscle fatigue and muscle wasting further complicating patient recovery. In addition, recumbent patients with muscle wasting are prone to megaesophagus and aspiration pneumonia. Renal function can also deteriorate as a result of poor nutrition as decreased urea concentration in the renal medulla results in a loss of the kidney's concentrating ability Poor nutrition can cause decreased muscle function leading to decreased motility and malabsorption in the gastrointestinal tract. Sadly, even cardiac muscle can become weak by the increased demand for oxygen consumption due to the hypermetabolic state from injury or illness.

In essence, no organ is spared during malnutrition. It is important to note that the interrelationships between organ function and nutrition are complex and delicate. Wherein no single parameter or observation can define the degree of nutritional insufficiency, being conscious of the nutritional need for mere patient maintenance is an important step in providing good patient care.

Development of malnutrition can be hospital related and not just a reflection at time of admission. Frequent diagnostics testing, stress from being apart from owners, lack of sleep, or unregulated pain can cause a patient to quit eating. Good communication between nursing staff should include a patient's behavior and eating habits during patient rounds. Other practices known to adversely affect the nutritional status of hospitalized patients include the failure to record a daily body weight, lack of nutritional intervention after surgical procedures, (particularly if the patient is kept sedated on heaving infusions of analgesia), medications causing inappetance or nausea, and improper diet types.