Administration of fluid therapy

Administration of fluid therapy

Carole Brown


The healthy body contains between 60% and 70% water, which is found inside and surrounding all the cells. This fluid maintains a balanced state within the body so that the normal metabolic processes can function efficiently – a process known as homeostasis. Dissolved in the body fluids are chemical materials that are essential for the body’s metabolism and which play a part in controlling the movement of fluid around the body. Many medical conditions and surgical procedures cause an upset in fluid balance and if nothing is done to correct this the animal may become severely dehydrated or go into shock and die. The purpose of fluid therapy is to replace any deficit so that the circulating fluid volume is restored and renal function is improved.

There are many types of fluid used in fluid therapy and the fluid replaced must be as close as possible, in terms of the chemical constituents and volume, to that lost from the general circulation. This chapter explains the theory that underpins the selection of fluids and describes in detail the procedures involved in supplying the fluid to the patient.

Procedure: Appreciation of water content in the body (Fig. 4.1)

1. Action: 100% total bodyweight.

    Rationale: 60% water + 40% other body structures.

2. Action: Intracellular fluid (ICF) = 2/3 of body fluid.

    Rationale: ICF is located within the cells.

3. Action: Extracellular fluid (ECF) = 1/3 of body fluid.

    Rationale: ECF is located outside the cells; plasma – water contained within blood, interstitial fluid bathing cells, transcellular fluid within specialized areas.

4. Action: Body fluids contain electrolytes, which yield ions.

    Rationale: It is important to know the electrolyte and ion composition of body fluids to ensure the correct fluid is administered.

5. Action: Ions are small water-soluble particles carrying one or more negative or positive charges. Sodium chloride (NaCl) is an electrolyte which dissociates into sodium ions and chloride ions when dissolved in water.

    Rationale: It is important to know which ions are in ICF and ECF to ensure that the correct fluid therapy is administered. Cations are ions that are positively charged; the main cations in ICF are potassium and magnesium and the main cation in ECF is sodium. Anions are ions that are negatively charged; the main anions in ECF are chloride and bicarbonate.

6. Action: Water balance and concentration need to be maintained equally within the body.

    Rationale: Osmosis is the process by which water moves from a low concentration to a high concentration through a semipermeable membrane. Osmotic pressure is the pressure needed to prevent osmosis from happening. Osmotic pressure is maintained in the healthy animal by various homeostatic mechanisms.

Procedure: Appreciation of water balance in the body

1. Action: Water intake – ingestion.

    Rationale: Ingestion of fluids and foods.

2. Action: Water intake – metabolism

    Rationale: Metabolism of fats and carbohydrates.

3. Action: Water loss – 50 ml/kg bodyweight/24 h.

    Rationale: This is the amount that needs to be replaced daily to ensure water balance.

4. Action: Sensible water loss – 25 ml/kg bodyweight/24 h.

    Rationale: Sensible loss via urine.

5. Action: Insensible water loss – 25 ml/kg bodyweight/24 h.

    Rationale: Insensible losses – respiratory, cutaneous and faeces.

6. Action: Water replacement = 50 ml/kg/24 h.

    Rationale: To balance water loss.

7. Action: Electrolyte replacement:

    Sodium 1 mmol/kg/24 h

    Potassium 2 mmol/kg/24 h.

    Rationale: To balance electrolyte loss.

8. Action: Metabolic acidosis = loss of alkaline ions.

    Rationale: Replace loss with fluid containing alkaline ions to correct acid/base imbalance.

9. Action: Metabolic alkalosis = loss of acidic ions.

    Rationale: Replace loss with fluid containing acidic ions to correct acid/base imbalance.

Procedure: Assessing level of dehydration of the patient

1. Action: Normal physical appearance despite a history of fluid loss.

    Level (degree of dehydration as a percentage of bodyweight): Slight > 5%.

2. Action: Mild to dry mucous membranes, slight decrease in skin turgor.

    Level: Mild 5–6%.

3. Action: Decrease in skin turgor; dry mucous membranes; mild tachycardia; sunken eyes; slight increase in capillary refill time.

    Level: Mild 6–8%.

4. Action: Marked decrease in skin turgor; dry mucous membranes; sunken eyes; weak pulse; increased capillary refill time; oliguria; cold extremities.

    Level: Moderate 10–12%.

5. Action: Very marked decrease in skin turgor; pale and dry mucous membranes; sunken eyes; tachycardia; cold extremities; muscle weakness; collapse; depression; anuria.

    Level: Severe 12–15%.

Procedure: Selection of fluids in relation to their action in the body

1. Action: Isotonic fluid.

    Rationale: Equal osmotic pressure to plasma – no fluid movement thereby maintaining equilibrium.

2. Action: Hypertonic fluid.

    Rationale: Greater osmotic pressure than plasma – thereby encouraging movement of fluid from cells into circulation.

3. Action: Hypotonic fluid.

    Rationale: Lower osmotic pressure than plasma – thereby encouraging movement of fluids into cells.

4. Action: Crystalloids.

    Rationale: These fluids contain small molecules that enter and temporarily increase the blood volume before passing into the cells and equilibrating with the ICF.

5. Action: Colloids.

    Rationale: These fluids contain large molecules that remain within the circulation, thereby increasing osmotic pressure and expanding plasma volume.

6. Action: Blood product – plasma.

    Rationale: This helps to expand plasma volume and treat hypoproteinaemia.

7. Action: Whole blood.

    Rationale: Used in cases where replacement of red blood cells and plasma volume expansion are required.

Procedure: Selection of fluid for specific needs

1. Action: 0.9% NaCl – normal saline (isotonic crystalloid).

    Rationale: Replace ECF. Gastric losses or loss of acidic ions from vomiting.

2. Action: 0.18% NaCl + 4% dextrose (isotonic crystalloid).

    Rationale: Maintenance requirements; primary water deficit replacement; neonatal ECF replacement.

3. Action: 5% dextrose (isotonic crystalloid).

    Rationale: Primary water deficit replacement.

4. Action: Hartmann’s solution (isotonic crystalloid).

    Rationale: Replace ECF. Diarrhoea and post gastric losses/alkaline ions.

5. Action: Ringer’s solution (isotonic crystalloid).

    Rationale: Replace ECF; gastric losses from vomiting.

6. Action: Haemaccel/Gelofusine (isotonic colloids).

    Rationale: Expand plasma volume; moderate to severe fluid loss and blood loss where no blood products are available.

7. Action: Plasma (blood product – isotonic).

    Rationale: Replace plasma proteins; expand plasma volume as above; clotting defects.

8. Action: Whole blood (isotonic).

    Rationale: Replace blood loss; meet any ongoing or anticipated blood loss; anaemia; circulatory insufficiency.

Procedure: Oral fluid therapy

Fluid choice

Hypotonic electrolyte solution or water.

1. Action: Select equipment – dosing syringe with catheter tip, towel, assistant, fluid.

    Rationale: A dosing syringe is the most suitable method of accurate administration. It is important to select all equipment prior to the procedure to ensure efficient method of administration.

2. Action: Measure correct volume of fluid in syringe.

    Rationale: Important to measure fluid replacement accurately to avoid excess or insufficient fluid.

3. Action: Request assistance to hold patient (see Chapter 1).

    Rationale: Ensure that the patient is kept at ease and feels safe.

4. Action: Support patient’s nose and mouth with left hand in normal position.

    Rationale: Firm but sympathetic handling will ensure fluid is delivered safely and effectively. Head must be in normal position to prevent aspiration pneumonia.

5. Action: Introduce the catheter tip syringe into the mouth between upper and lower premolars above the tongue surface.

    Rationale: This area is the most suitable to administer fluid safely and accurately.

6. Action: Slowly introduce 5–10 ml of fluid into the mouth and allow the patient to swallow. Stroke the ventral aspect of the pharynx to encourage swallowing.

    Rationale: Avoid giving too much fluid at any one time as this may induce choking. Allow patient to swallow and breathe between administrations.

7. Action: Continue until required volume has been delivered or the patient becomes agitated.

    Rationale: Only continue if patient is taking fluid well and swallowing between doses. At any time if the patient gets distressed or fails to swallow, stop the procedure immediately.

8. Action: Dry the patient’s mouth and surrounding area and replace in ready prepared clean kennel.

    Rationale: Always dry the area to help prevent heat loss and make the patient comfortable.

9. Action: Record total fluid volume given and the frequency on the hospital record.

    Rationale: Ensure record keeping is accurate to prevent over- or under-administration.

10. Action: Dispose of equipment safely and appropriately.

    Rationale: It is essential to dispose of equipment correctly to avoid contamination and accidents.

Procedure: Subcutaneous fluid therapy

Fluid choice

Any crystalloid isotonic solution such as 0.9% NaCl, 0.18% NaCl + 4% dextrose or Hartmann’s solution.

1. Action: Select and prepare equipment – prewarmed fluid, measured volume in sterile syringe with new sterile needle attached (maximum 10–20 ml/kg/site), clippers, surgical skin scrub, gloves, swabs (Fig. 4.2).

    Rationale: Fluid must be prewarmed to prevent shock and discomfort and aid absorption. Isotonic or hypotonic fluid is used to promote absorption. Ensure all equipment is prepared in advance to allow for efficient procedure.

2. Action: Request assistant to restrain patient in lateral recumbency.

    Rationale: Firm, effective handling ensures that the patient remains comfortable throughout procedure.

3. Action: Clip an area of approximately 3 × 3 cm on either side of the thorax over the ninth rib, midway between ventral and dorsal borders.

    Rationale: Area must be free of hair to reduce the risk of infection. This area allows effective movement and absorption of fluid.

4. Action: Prepare skin aseptically with surgical scrub solution. Wear gloves.

    Rationale: Skin must be cleaned aseptically to reduce risk of infection.

5. Action: Infiltrate local anaesthetic into the prepared site as per veterinary surgeon instructions. Drape the area.

    Rationale: Local anaesthetic will desensitize the area, preventing pain and discomfort. Draping the area will help to maintain asepsis.

6. Action: Tent the skin and introduce the needle, attached to the fluid-filled syringe, subcutaneously.

    Rationale: Administration must be subcutaneous, avoiding any puncture of thoracic cavity.

7. Action: Withdraw the plunger of the syringe.

    Rationale: To check that a vein has not been punctured by accident.

8. Action: Administer the volume of fluid slowly and withdraw the needle (maximum 10–20 ml/kg/site).

    Rationale: Fast infusion of fluid can cause considerable discomfort.

9. Action: Massage the area.

    Rationale: To ensure even and effective distribution.

10. Action: Repeat the procedure on the other side of the thorax.

    Rationale: To ensure equal distribution in the body.

11. Action: Remove the drapes and dry the area. Allow the patient to resume sternal recumbency and place back in the kennel.

    Rationale: Ensure patient is comfortable in kennel.

12. Action: Dispose of equipment safely and appropriately.

    Rationale: It is essential to dispose of equipment correctly to avoid contamination and accidents.

Procedure: Intraperitoneal fluid therapy

Fluid choice

Any isotonic crystalloid fluid such as 0.9% NaCl; 0.18% NaCl + 4% dextrose; Hartmann’s solution.

1. Action: Select and prepare equipment – prewarmed fluid, measured volume in sterile syringe with sterile new needle attached, clippers, surgical skin scrub solution, swabs, gloves.

    Rationale: Avoid shock and drop in body temperature by prewarming fluid. Prepare all equipment in advance of procedure to ensure efficient administration.

2. Action: Assistant to restrain patient in dorsal recumbency and reassure patient throughout procedure.

    Rationale: To present the correct area for administration and encourage the viscera to gravitate away from site, thereby avoiding puncture during procedure.

3. Action: Clip area surrounding umbilicus.

    Rationale: Reduce risk of infection by clipping hair, allowing a wide margin around umbilicus.

4. Action: Prepare skin aseptically and drape area.

    Rationale: To reduce risk of infection.

5. Action: Infiltrate local anaesthetic into prepared site – region of umbilicus – as per veterinary surgeon instructions.

    Rationale: To desensitize area prior to administration of fluid.

6. Action: Introduce sterile needle attached to fluid syringe through the skin and central line (linea alba) into the peritoneal cavity.

    Rationale: Ensure asepsis maintained and introduction efficient and smooth.

7. Action: Withdraw plunger of syringe.

    Rationale: Accident – if blood appears in hub of syringe, withdraw and start again. If urine or gut contents appear in the syringe, the bladder or intestine may have been punctured – withdraw and start again.

8. Action: Introduce prewarmed fluid into the peritoneal cavity.

    Rationale: If any resistance is felt, stop and restart procedure from point 6.

9. Action: Withdraw needle and syringe, putting gentle pressure over injection site.

    Rationale: Clean, swift removal of needle to prevent any discomfort. Pressure to prevent leakage of body fluid.

10. Action: Remove drapes and dry area. Allow patient to regain sternal recumbency, reassure and replace in kennel.

    Rationale: Resume normal position as soon as possible to restore equilibrium. It is important to ensure patient is comfortable before placing back in kennel.

11. Action: Record fluid administration details.

    Rationale: To ensure accurate monitoring.

12. Action: Dispose of equipment safely and appropriately.

    Rationale: It is essential to dispose of equipment correctly to avoid contamination and accidents.

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Jan 8, 2017 | Posted by in NURSING & ANIMAL CARE | Comments Off on Administration of fluid therapy

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