The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [255]
Dehydration can ultimately cause a reduction in circulating volume. As with any change in a homoeostatic state, the body in health has the ability to compensate but in ill health these mechanisms are often inadequate. Untreated dehydration will quickly lead to a drop in blood pressure and a rise in heart rate (to compensate for the fall in blood pressure). A fall in blood pressure will firstly lead to inadequate renal perfusion, causing a rise in metabolites, acidosis, acute renal failure and eventual toxaemia. Untreated, other organs will suffer from underperfusion, possibly resulting in ischaemia, organ dysfunction and eventual organ failure (Sumnall 2007).
Additional signs and symptoms of dehydration are thirst, weight loss, decreased urine output, dry skin and mucous membranes, fatigue and increased body temperature (Goertz 2006).
Treatment of dehydration includes the replacement of lost fluid and electrolytes but caution must be exercised. If the dehydration is mild, slower fluid replacement is advised, in order to prevent further complications in shifts in electrolytes. However, if hypovolaemia exists with the signs and symptoms of circulatory shock, low blood pressure and organ dysfunction, aggressive fluid replacement is advised (Jevon 2010).
Nutritional status
Definitions
Nutritional status refers to the state of a person’s health as determined by their dietary intake and body composition. Nutritional support refers to any method of giving nutrients which encourages an optimal nutritional status. It includes modifying the types of foods eaten, dietary supplementation, enteral tube feeding and parenteral nutrition (NCCAC 2006).
Anatomy and physiology
The normal process of ingestion of food or fluids is via the oral cavity to the gastrointestinal tract.
The normal swallow involves a number of stages, starting with the oral preparatory stage which is influenced by the sight and smell of food. Food or liquid is placed in the mouth and the lips are closed. After chewing and mixing with saliva, it forms a cohesive mass (bolus) that is held on the centre of the tongue. Swallowing is a voluntary task that requires intact functioning of the cranial nerves in addition to intact motor and sensory input for lips, jaw, teeth, tongue and palate.
The pharyngeal stage of swallowing, which is involuntary (see Figure 8.3), occurs as the food bolus crosses the mandible/tongue base as the palate closes, sealing entry to the nasal cavity and reducing risk of nasal regurgitation. Movement of the tongue base and posterior pharyngeal wall squeezes the bolus down the pharynx. Involuntary movements of the larynx (voice box), vocal cords and epiglottis protect the airway and open the cricopharyngeus. The bolus travels from the cricopharyngeus to the gastro-oesophageal junction and peristaltic action then transfers the bolus down the oesophagus (Logemann 1998).
Figure 8.3 Pharyngeal stage of swallowing.
The gastrointestinal tract is the site where food is ingested, digested and absorbed, thus enabling nutrients to be used by the body for growth and maintenance of body functions. Food ingested is moved along the gastrointestinal tract by peristaltic waves through the oesophagus, stomach, small intestine and large intestine. The passage of food and fluid through the gastrointestinal tract is dependent on the autonomic nervous system, gut hormones such as gastrin and cholecystokinin, the function of exocrine glands such as the parotid, pancreas and liver and psychological aspects such as anxiety. Sphincters situated between the stomach and duodenum, the ileocaecal valves and the anal sphincter also regulate the rate of passage of food and fluids through the tract.
Before food can be absorbed, it must be digested and broken down into molecules that can be transported across the intestinal epithelium which line the gastrointestinal tract.