2. Outline
• Importance of water
• Body water compartments
• Ions & Electrolytes
• Dehydration
• What is Fluid Therapy?
• Phases of Fluid Therapy
• Fluid types
• Administration
• Monitoring
21. Normosol-R
Isotonic
140 mEq / L of Sodium
98 mEq / L of Chloride
5 mEq / L of Potassium
3 mEq / L of Magnesium
27 mEq / L Acetate
23 mEq / L Gluconate
22. Lactated Ringers Solution
Isotonic
130 mEq / L of Sodium
109 mEq / L of Chloride
4 mEq / L of Potassium
3 mEq / L of Calcium
28 mEq / L of Lactate
24. 5% Dextrose in Water
Hypertonic
“D5W”
50 g/L of Dextrose
No other electrolytes
Relatively no caloric content
Never given subq
25. 0.45% Sodium Chloride + 2.5% Dextrose
Isotonic
“Half & half”
77 mEq / L of Sodium
77 mEq / L of Chloride
25 g / L of Dextrose
No other electrolytes
33. Oxyglobin
Purified solution of bovine hemoglobin
Increases O2 to tissues
Expands plasma volume
No RCB’s
Store at room temp
Good for up to 3 years
40. Conclusion
Fluid therapy is fundamental to many aspects of small
veterinary medicine.
IV Fluids are used as a supportive measure in
hospitalized patients, and as life saving measures in
many critical patients.
The veterinary technician is responsible for monitoring
patients receiving IV fluid therapy, noticing, recording
and reporting changes in a patient’s condition.
Therefore we must understand the basic principles of
fluid therapy.
Water - single most important nutrient for the body. Fat – can lose almost all. Protein – more than ½ lose. 10% water loss = death transports nutrients Essential for normal digestion Elimination of waste products from the kidneys also requires a large amount of water Contributes to temperature regulation by transporting heat away from the working organs through the blood Absorbs heat with a minimal increase in temperature Important – many heat generating reactions within the body – allows to continue with a minimal change in body temperature.
Water comprises 60% of body weight. Of this, 40% is intracellular, and 20% is extracellular.
The different compartments that house body water The membranes separating these compartments are freely permeable to water, which moves under the force of osmotic pressure until the osmolality of each compartment is equal. When “free water” (no osmotically active particles) is added to one body compartment, it is distributed evenly throughout all body water compartments.
is the process of water moving through a semipermeable membrane from an area of lower solute concentration to that of a higher concentration. The result is that the solute concentration on either side of the membrane is the same
The appropriate compartments for a variety of ions. - Extracellular & intracellular fluid compartments contain different concentrations of important solutes called ions. These are electrically charged particles found in the body water compartments. The term electrolyte refers to the combination of ions to form a substance that will break down in water. Electrolytes are important in maintaining acid-base status within the body. They also provide osmotic pressure & regulate the movement of body water between compartments The extracellular & intracellular spaces contain high concentrations of sodium (Na+), chloride (Cl-), potassium (K+), and magnesium (mg++)
Sodium plays an important role in maintaining the volume of water in the extracellular space. It is exchanged between the intracellular & extracellular spaces easily. is responsible for the exchange of Na+ & K+ between the intracellular & extracellular spaces. When sodium in a cell reaches an unsuitable level (too high) the pump exchanges a sodium ion for a potassium ion. This maintains a higher concentration of sodium outside the cell, which is important since water will diffuse to areas of higher sodium concentration.
Solutions with different concentrations have specific effects on the cell. Isotonic solutions do not cause extensive movement of water (H2O) into or out of the cell. Isotonic – having the same osmotic pressure (similar concentration to plasma) Hypertonic solutions cause movement of H2O out of the cell. Hypertonic – having a higher osmotic pressure Hypotonic solutions cause movement of H2O into the cell. Hypotonic – having a lower osmotic pressure
Fluid Therapy is supportive. The underlying disease process that caused the fluid, electrolyte, and acid-base disturbances in the patient must be diagnosed and treated appropriately replacing ongoing fluid losses enhancing perfusion replenishing dehydrated cells maintaining some level of cellular energy May be used to provide maintenance fluid requirements May be used to administer medications and electrolytes replace intravascular volume (perfusion) or interstitial fluid volume (dehydration) correct electrolyte abnormalities (hypercalcemia, hypokalemia, hyper- or hyponatremia).
Intravenous fluid therapy is the preferred route of administration for hypovolemic (low BP – inadequate level of blood volume) patients and most dehydrated patients Dehydration causes peripheral vasoconstriction to protect core perfusion therefore subcutaneous tissue are not well perfused and subq fluids are not well absorbed into the interstitial and intravascular spaces Subcutaneous fluids can be absorbed slowly and can be effective in mildly dehydrated patients and in management of patients with renal disease.
The volume and rate of administration are guided by pathologic conditions such as cardiac disease Renal disease systemic inflammatory response syndrome diseases fluid loss into the third body fluid space blood pressure pulmonary and cerebral edema
3 phases of fluid therapy: resuscitation, rehydration, and maintenance. Resuscitation - most patients in shock require rapid administration of a large volume of fluids to expand the intravascular space and correct perfusion deficits Dehydrated patients may also require sustained administration of crystalloid fluids over a period of hours to replace fluid losses from the interstitial and intracellular spaces. Regardless of their underlying disease, severely dehydrated patients can be in shock and require a resuscitation phase of fluid therapy before initiating the rehydration phase However, not all patients in shock are dehydrated and thus may or may not require a rehydration phase of therapy
urgently require fluid therapy - common physical examination altered mental status cool extremities tachycardia or severe bradycardia pale mucous membrane prolonged or absent crt reduced or absent peripheral pulses hypotension Fluid administration is contraindicated in patients with predominantly cardiogenic forms of shock
need for a rehydration phase is dependent on the underlying condition of the patient Shock & dehydrated patients after fluid resuscitation Surgical patients may not need - maintenance of venous access for emergencies and to maintain renal perfusion during anesthesia medical patients - depends on an assessment of hydration status
amount of fluids needed to meet the metabolic requirements of a patient. Metabolic demands vary between caged vs. active patients, as well as healthy vs. sick patients. We often tend to use simple formulas or universal recipes such as 1 ml/lb/hour or 40 ml/kg/day or [30 x (weight in kg)] + 70 = number of mls per day doesn’t work for all patients - these linear formulas tend to under dose small patients and overdose large patients especially significant when the kidneys aren’t functioning properly (fortunately, they often correct for our inaccurate fluid plans) when there is an increased risk of volume overload (heart failure) If we use multiples of maintenance rates (“twice maintenance,” “three times maintenance,” etc.) to address deficits due to dehydration or anticipated ongoing losses, such errors will be multiplied by the same factor
Any fluid therapy plan is just a plan It should be re-evaluated by monitoring the patient’s hydration (mucous membrane moisture, skin turgor) and perfusion (mucous membrane color, CRT, pulse quality, heart rate) Patients with normal hydration unable to consume sufficient water to sustain fluid balance require maintenance fluid therapy with crystalloid solutions.
There are two general categories of fluids used in veterinary medicine Crystalloids Colloids These fluid types can further be broken down into various categories osmolality replacement solutions (Normosol-R, LRS), blood products (fresh frozen plasma, FFP), their synthetic nature (Vetastarch), balanced or unbalanced (Lactated Ringer’s solution [LRS] vs. 0.9% NaCl) their purpose (electrolyte replacement, colloidal properties) We use these at BVH but there are others
contain crystals of salts with a similar composition to extracellular fluid space may contain a variety of electrolytes such as Na+, Cl−, K+, Mg2+, Ca2+, and non-electrolytes such as amino acids or buffers (acetate, lactate, bicarbonate) to balance acid–base status. often used to maintain daily fluid requirements and replace fluid deficits and ongoing losses relatively inexpensive safely administered in large volumes to most patients without preexisting renal or cardiac disease or cerebral edema able to diffuse into the intravascular, interstitial, and intracellular compartments may be used to expand the intravascular space however approximately 80% of the volume infused will be redistributed to the interstitial and intracellular space within 1 hour of infusion This makes them effective at rapid volume restoration in hypovolemic states, but may require large volumes, and repeated boluses to restore effective circulating volume. In contrast, they are highly effective at interstitial rehydration.
an isotonic replacement crystalloid with acetate as its buffer. - contains Is a buffered solution and because it contains some magnesium may be a good choice for critical patients who may be magnesium deficient.
LRS is an isotonic buffered replacement crystalloid - contains has a slightly lower sodium level than that of the extracellular fluid, which may make it a good choice in hypernatremic patients ( low sodium in blood plasma) does not contain magnesium contains some calcium.
– contains only no other electrolytes making it a weak replacement solution not a maintenance solution. It is also very acidic with a pH of 5.0. most appropriate in cases of hyponatremia ( low sodium) or hypochloremia, (low chloride) and hypercalcemia ( high calcium) They may also require additional supplemental potassium added to their fluids based on the degree of potassium blood levels they have.
– contains and is used in free water replacement The dextrose is rapidly metabolized into carbon dioxide and H2O Never give subq- hyperosmolar and cause skin necrosis or sloughing Dextrose solutions such as D5W are not a good choice as replacement fluids. In fact, you can kill a patient by giving a large amount of D5W. Once the glucose has been absorbed, we are left with free water, which is distributed to the various fluid compartments. That water is absorbed by all cells, which can lead to intracellular edema. When this happens in the brain, it can be deadly. Dextrose in IV fluids provides an insignificant amount of calories, which is definitely not enough to sustain a patient’s energy requirements.
(half and half)– contains still considered isotonic because of the addition dextrose makes it so used to replace fluids in patients that are hypernatremic, (high serum sodium) as a lower sodium solution will cause favorable shifts in lowering sodium content. Again, potassium should be added if the patient is hypokalemic, or simply to add maintenance potassium during diuresis. Never give subq - hyperosmolar and cause skin necrosis or sloughing
Crystalloid This fluid typically has a specific use - to rapidly draw water from the interstitial space into the intravascular space and to rapidly expand the intravascular volume As with all crystalloids, the fluid will extravasate into the interstitium within 1 hour in a healthy animal, and possibly sooner in a diseased animal Often administered with a colloid because the colloid will help to retain at least some of the water it draws into the intravascular space should not be given to patients who are hypernatremic (high sodium) use in head trauma patients with hypovolemia, as it will decrease cerebral edema, and increase intravascular volume
The particular crystalloid to administer is determined by the measured or estimated sodium and potassium concentrations and by the osmolality of both the animal’s serum and the fluid to be administered When blood parameters are unknown, it is best to initially select a fluid with electrolyte content, pH, and osmolality most like serum; Lactated Ringer’s or Normosol-R for example.
When serum sodium is normal a balanced isotonic electrolyte solution (LRS, Norm R) can be used for volume replacement Low serum sodium content, volume replacement should be with isotonic saline (0.9%) High serum sodium values most commonly reflect a loss of solute-free water Patients are re-perfused and rehydrated using an isotonic fluid (LRS, Norm R) Then the free water can be replaced using half & half or D5W must be done carefully, and the sodium concentration lowered slowly to prevent edema (especially to brain)
When serum potassium estimations are normal, a balanced electrolyte solution can be used. Serum potassium values should be obtained before supplementation when possible. Hypokalemia ( deficiency of potassium in the blood) can be difficult to recognize clinically - Nova Start with initial volume replacement without additional potassium Once stabilized, potassium chloride should be added to the fluids Often, 20 mEq of KCL is added to a liter of balanced isotonic crystalloids Clinical conditions that may require potassium-free solutions include oliguric ( decreased production in volume of urine) renal failure, heat stroke, adrenal insufficiency, and massive muscle breakdown When it is determined that the hyperkalemia (abnormally high potassium) will resolve after volume replacement and fluid diuresis (such as in feline urethral obstruction), a balanced electrolyte solution should be used. These solutions have a normal pH and promote potassium excretion.
A large molecular weight particle that acts as an effective volume expander by drawing fluid from the interstitial fluid compartment into intravascular space When administered with a crystalloid the colloid helps to retain the crystalloid within the vascular space for a longer time than if the crystalloid had been given alone Examples include: Vetastarch Oxyglobin species-specific albumin human albumin solutions
Contains 6% hydroxyethyl starch in 0.9% sodium chloride injection is a clear to slightly opalescent colorless to slightly yellow isotonic
like FFP & FP contain colloidal properties as they contain large molecules may be used as volume expanders in a critical emergency have the benefit of being isotonic and also contain coagulation factors and circulating anticoagulants not routinely used for this purpose, and are more often used as a transfusion product.
Hemoglobin contains no surface antigens, so transfusion reactions are unlikely to occur because of incompatibility may be unavailable
Plasma is very rich in albumin Dirived from human serum – sterilized Donors screened for hep B, hep C, HIV
rapid volume expansion by expanding plasma colloidal osmotic pressure (COP) Administering any colloid into the vasculature will retain the fluid currently there, and draw fluid from the interstitium into the vascular space to help with perfusion will “last longer” in the IV space because they mostly do not fit between epithelial tight junctions diseases where proteins are lost (such as protein losing enteropathy), plasma COP is reduced, allowing fluid to leech into the intersitium creating edema Synthetic colloids are often given to hypotensive patients in 5 to 10 ml/kg over 5 to 15 minutes
Fluid pumps safest & most effective method to administer IV fluids Gravity feed infusion - next best option Infusion sets have drip chambers that are calibrated (and may vary by manufacturer) to deliver a specific number of drops equal to 1 ml. of fluid Common drip sets include 10, 15, 20, and 60 drops/ml IV fluid set we use at Bulger is a 10 drop/ml line. Our subq fluid sets, which can also be used for IV fluids, is a 15 drops/ml Fluid rates can be calculated based on the number of drops that fall, into the drip chamber, per minute using the formula - Fluid volume to be infused (in mls.) divided by the number of hours = mls per hour
The actual volume the patient receives should be recorded by the nursing staff All additives to fluid bags must be clearly listed on a label attached to the bag must include: name of the drug added the volume added date and time added initials of the person adding
The body, of most patients, allow for a considerable margin for error in fluid therapy, provided that the heart and kidneys are normal. More accurate calculations are required for the critical patient whose kidneys and cardiovascular system may be compromised a patient on fluid therapy must be monitored by a dedicated and knowledgeable veterinary technician We are crucial in this process we often notice changes associated with fluid intolerance or overload quicker than the veterinarians who are not constantly with their patient
A main complication of fluid therapy is fluid intolerance (formally called fluid overload) Fluid intolerance occurs when the patient cannot tolerate the calculated volume of fluid they received There was no error, the patient simply could not tolerate this volume fluid overload which implies an error was made A few signs of (there are many more) often the first sign is increased respiratory rate / effort Thus, instituting careful respiratory watches on these patients is essential Harsh lung sounds can also indicate pulmonary edema, caused by high hydrostatic pressures within the pulmonary vasculature Clear nasal discharge can also be common, as fluid weeps in the sinus spaces, and a wet cough can also occur from fluid in the lower airways Chemosis (swollen conjunctiva) Tachypnea can result from pulmonary edema Peripheral edema can result from excessive interstitial hydration Cats are extremely susceptible to fluid overload
