Ch 5 Fluids Flashcards
what are % total body water Int’s and extracellular compartnebts?
Water constitutes approximately 60% of body weight
Na+-K+/ATPase;
Which direction Intra/extracell,
Which high, low intracellular?
Na+ OUT
K+ IN
to the cell, consuming adenosine triphosphate (ATP)
Na+ concentration is very high in the extracellular fluid and very low in the intracellular fluid, and K+ is very high in the intracellular fluid and very low in the extracellular fluid
Movement of fluid from the intravascular to extravascular (interstitial and intracellular) space occurs at the level of the capillary.
endothelial barrier is a layer of glycoproteins and proteoglycans produced by the endothelium called the glycocalyx.
reabsorption of fluid requires what intravascular pressure?
increased intravascular oncotic pressure or decreased intravascular hydrostatic pressure
fluid filtration
decreased intravascular oncotic pressure or increased intravascular hydrostatic pressure
What is Oncotic pressure ?
Hydrostatic pressure?
osmotic pressure
(globulins, fibrinogen, and albumin)
intravascular blood pressures and vascular resistance.
increased fluid losses (hypotonic, isotonic, and/or hypertonic) and decreased intake may lead to dehydration
losses can also result in decreased effective circulating volume
losses can also result in decreased effective circulating volume
5-12% dehydration signs
how calculate fluid required
Treatment of shock
Important to deliver what to tissue?
Normalises what to ensure tissue perfusion? (5)
requires restoration of organ perfusion
Oxygen delivery to tissue DO2
Normalization:
- intravascular volume
- preload
- MAP
- cardiac output
- oxygen content
are crucial in supporting tissue perfusion
decrease in production of ATP. This energy deficit compromises the function of the Na+-K+/ATPase membrane pumps and causes
disruption of the cell membrane
exposure of subendothelial > activation of the platelets, clotting cascade
bacterial translocation in the intestinal tract.
SIRS, sepsis, and multiple organ dysfunction commonly result.
Perioperative Fluid Therapy
anesthetic drugs commonly have negative effects on the heart, blood pressure, and baroreceptor response
Tissue ischemia can interfere with wound healing and normal tissue defenses
dogs 5 mL/kg/h of crystalloids and cats started at 3 mL/kg/h
Close monitoring of the animal’s vital signs, blood pressure, and pulse oximetry reading
(goal-directed) approach for resuscitation
Aim to achieve (5)?
aimed to achieve:
- central venous pressure >8 to 12 mm Hg
- mean arterial pressure >65 mm Hg
- urine output >0.5 mL/kg/h
- arterial oxygen saturation [SaO2] >93%
- hematocrit >30%) within 6 hours.
Fluid/product types and uses (5) for shock
Isotonic crystalloids
(replacement fluids) are electrolyte-containing fluids with a composition similar to that of extracellular fluid
“Maintenance” crystalloid
hypotonic and contain less sodium
hypertonic crystalloids,
synthetic colloids
blood products
isotonic crystalloid
used to expand the intravascular and interstitial spaces and to maintain hydration
extracellular-expanding fluids,” and 75% of the volume redistributed to interstitial space
NaCl, LRS, Plasmalyte
Excessive fluid administration
lead to
interstitial edema, pulmonary edema, and cerebral edema, all of which will decrease oxygen delivery and organ function.
increased risk:
low colloid osmotic pressure, pulmonary contusions, cerebral trauma, renal disease, or cardiac disease, substantial hemodilution of red blood cells, plasma proteins, clotting factors, and platelets can occur.
Surgical patients with head trauma
- Periop patients with severe hypoNa or hyperNa
- Surgical patients with hypoCl metabolic alkalosis
- Surgical patints with severe metabolic acidosis, not due to lactate
Head trauma –> 0.9%NaCl. Has the highest Na conc and therefore is least likely to cause a drop in osmolality and cerebral oedema
Hypo/hyperNa –> Choose the fluid which most closely matches their Na. Too rapid a drop can cause cerebral oedema. To rapid an increase can cause central pontine myelinolysis
HypoCl met alkalosis –> 0.9%NaCl as it is the highest in Cl and will help normalise the pH
Metabolic acidosis –> Crystallois with a buffer (lactate, acetate, gluconate). NOT NaCl
hypotonic fluids
maintenance fluids
0.45% NaCl
0.45%NaCl with 2.5% dextrose
Plastalyte 56
Plasmalyte M with 5% dextrose
Normosol M with 5% dextrose
5% Dextrose in water (D5W)
Dextrose is rapidly metabolised to H2O and CO2 (good source of free water)
Maintenance fluids low in sodium, chloride, and osmolarity
hypotonic fluids
maintenance fluids
Contraindicated as bolus therapy in animals with hypovolemia
Large volumes can lead to a rapid decrease in osmolarity and subsequent cerebral edema
Hypertonic (7.0% to 7.5%) sodium chlorid
transient osmotic shift of water from the extravascular to the intravascular
4 to 6 mL/kg over 10 to 20 minute,
transient (<30 minutes),.
Rates exceeding 1 mL/kg/min leads to vagally mediated hypotension, bradycardia, and bronchoconstriction and should be avoided
treatment of head trauma or cardiovascular shock in animals >30 kg
Synthetic colloid solutions
0.5 to 2 mL/kg/day.
total dose of <20 mL/kg/day is advised to avoid side effects.
treatment of ? (2)
carge molecules (molecular weight >20,000 daltons
increase the colloid osmotic pressure of the plasma > pull fluid into the intravascular space.
colloid particles help to retain this fluid in the intravascular space in the animal with normal capillary permeability
Treats: shock and hypoproteinemia
blood loss requiring transfusion
fresh whole blood or packed red blood cells and fresh frozen plasma should be used to stabilize clinical signs of shock
Hypokalaemia
CS: muscle weakness, cardiac arrhythmias, cervical flexion and pelvic limb weakness
less than 5.0 mEq/L
Decreased Intake
diet
fluids
Increased Loss
Chronic renal failure
Postobstructive diuresis
Loop diuretics
- Mineralocorticoid excess
Hyperadrenocorticism
Hyperaldosteronism - GIT loss
V+ gastric contents
Diarrhea
Translocation Into Intracellular
* Alkalemia
* Insulin
* Glucose
Tx: correct underlying disorder and supplementation K+, 0.5mEq/kg/hr
Calcium
roles in neural excitability, muscle contraction, and blood coagulation.
99% bone, 1+ intra.extracell
ionized (active form), protein bound, and chelated.
Three hormones: parathyroid hormone, vitamin D (cholecalciferol), and calcitonin.
act at the kidney, intestine, and bone to regulate calcium balance.
Calcitonin inhibit bone resorption
Acid-BAse
buffers play an important role in acid-base homeostasis in the body
bicarbonate, proteins, and phosphate
regulation of PaCO2 through alveolar ventilation in the lungs and maintenance of normal [HCO3−] in the extracellular fluid by the kidneys
chemoreceptors that sense changes in blood pH
95% of filtered HCO3− is reabsorbed in the proximal tubule
base excess
+
ANion gap
−4 to +4 mEq/L
assess the metabolic component of acid-base disturbances.
negative = nonrespiratory acidosis, and positive = nonrespiratory alkalosis.
Electrolyte derangements are often the first sign of an acid-base disorder
electroneutrality. increased anion gap acidoses include ketoacidosis, lactic acidosis, ethylene glycol toxicosis, salicylate toxicosis, and uremic states.
in dogs 11 to 26 mEq/L, and in cats 13 to 27 mEq/L.
metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis
Primary disorders are accompanied by secondary adaptive compensation by the opposing system of acid-base regulation.
