Fluids and Feeding Flashcards
How much fluid is distributed inside of the cells?
2/3 of the total body fluids
How much fluid is in the Extracellular space?
1/3 of the total body fluids
What is the extracellular space divided into?
Intravascular space (inside blood vessels) – 20% of the extracellular fluid Interstitial space – the functional tissue space between and around cells – 80% of the extracellular fluid The “third space” – the “third” extracellular space
What is the third space?
Areas of the body that do not normally contain fluid: Peritoneal cavity (forming ascites) Pleural cavity (forming pleural effusions) Pericardial cavity (forming a pericardial effusion) Joints (forming joint effusions)
Is the fluid in the third space desirable?
No. When fluid moves into a non-functional space, this may come at the expense of the intravascular space, resulting in hypotension and reduced perfusion of tissues.
What are some sources of fluid intake?
Sources of fluid intake include:
Oral fluids
Nasogastric or PEG feeds
Intravenous fluids (including IV medications)
Total parenteral nutrition
What is insensible fluid loss?
Insensible fluid loss is a term that refers to fluid output that is difficult to measure, such as through respiration (breathed out), in stools, through burns and from sweat. This varies a lot and can only be estimated. It may account for a large volume (over 800mls per day) in patients with significant diarrhoea, high stoma output or sweating with a high fever.
What does a positive fluid balance chart indicate?
If they have a negative fluid balance, they may require additional IV fluids, and if they have a positive fluid balance, they may require less IV fluid
Having an abnormally low amount of extracellular fluid can be referred to as what?
hypovolaemia or volume depletion
What are signs of hypovolaemia?
Hypotension (systolic < 100 mmHg) Tachycardia (heart rate > 90) Capillary refill time > 2 seconds Cold peripheries Raised respiratory rate Dry mucous membranes Reduced skin turgor Reduced urine output Sunken eyes Reduced body weight from baseline Feeling thirsty
Why can patients with third spacing present as hypovolaemia?
Patients with third-spacing may have a low level of fluid in the intravascular space, but excessive fluid in other areas (such as the interstitial space or peritoneal cavity). This can give signs of hypovolaemia (e.g., hypotension, tachycardia and prolonged capillary refill time) and signs of fluid overload (e.g., oedema and ascites).
What are the indications for IV fluids?
Resuscitation (e.g., sepsis or hypotension)
Replacement (e.g., vomiting and diarrhoea)
Maintenance (e.g., nil by mouth due to bowel obstruction)
What are the two types of fluid?
Crystalloids
Colloids
What are crystalloids
Crystalloids are essentially water with added salts or glucose.
Why does normal saline carry a risk for acidosis?
Normal saline also carries a risk of causing metabolic acidosis due to adding so much chloride (hyperchloraemic acidosis). For these reasons, Hartmann’s or Plasma-Lyte are often better options.
What are colloids and what do they help?
Colloids contain larger molecules that stay in the intravascular space longer. Theoretically, this helps to retain fluid in the intravascular space.
What is an example fo a colloid?
human albumin solution, which may be used in patients with decompensated liver disease.
What does tonicity refer to?
Tonicity refers to the osmotic pressure gradient between two fluids across a membrane. This determines whether water molecules will move across the membrane by osmosis, from the area of lower concentration of solutes to the area of higher concentration of solutes.
