Unit 1 Flashcards
What is the Packed Cell Volume (PCV) (a.k.a. Hematocrit)
The percentage of blood volume that is composed of red blood cells rather than plasma
Where are red blood cells produced
bone marrow
What is the Total Protein (TP)
The quantity of protein contained in plasma. Under normal circumstances, protein is maintained in the bloodstream because protein molecules are larger than openings in blood vessel walls. If vessels are abnormal, protein can leak out of vessels.
What is the main function of the protein in the plasma?
is to influence fluid movement to maintain plasma volume within the vessels
What is normal PCV and TP in adult dogs and cats
Adult Dogs: PCV: 35-55%, TP: 5- 7 g/dl Adult Cats: PCV: 27-47%, TP: 5-7 g/dl (numbers can vary slightly depending on the population and laboratory, and will be lower in neonates and pediatrics)
When should you perform a PCV and TP test?
Any animal presenting for emergency care that is not completely healthy
What are causes of low PVC?
- Anemia (blood loss, red cell destruction, poor bone marrow production)
- Fluid overload
What are the causes of high PVC?
- Dehydration/ Plasma fluid loss
- Abnormal red blood cell production (a rare condition called polycythemia)
- Splenic contraction (The spleen stores RBC)
What are causes of high TP?
- Dehydration (fluid lost from plasma while protein remains)
- Excessive production of globulin protein (an immune protein)(Example: feline infectious peritonitis, chronic inflammatory disease)
Causes of High PCV with normal TP
- Normal for breed
- Splenic contraction
Causes of High PCV with low TP
Splenic contraction and/or dehydration with protein loss (this pattern characteristic for hemorrhagic gastroenteritis – a severe, acute GI bleeding disorder)
Causes of high PVC and high TP
Dehydration
Causes of low PCV with normal TP
Anemia from red blood cell destruction (example: Immune-mediated hemolytic anemia)
Causes of low PVC with low TP
Anemia from blood loss, or excessive fluid administration and overhydration
Causes of low PCV with high TP
Anemia and protein overproduction (example: feline infectious peritonitis)
What are white blood cells (WBC)
Blood cells vital to immune function in the body. There are various types of white blood cells with different functions.
Where are WBC made?
Most WBC are made in the bone marrow; however, lymphocytes are made in lymphoid tissue such as lymph nodes.
What are the types of WBC
neutrophils, lymphocytes, eosinophils, basophils
Neutrophils
Sudden response to acute infection. Short (4-6 hour) life span. Largest proportion of WBC
- “Segmented”: Mature adult neutrophils
- “Band”: Immature or young neutrophils – increase occurs with active or sudden infection
Lymphocytes
Provides “memory” to the immune system to respond rapidly to repeat invaders. Present in low numbers.
Eosinophils
Important in allergic or parasitic disease. Very low or absent normally.
Basophils
Similar to eosinophils, function in allergic or parasitic response. Very low or absent normally.
What are normal WBC and platelet counts in dogs and cats?
Dogs: WBC: 6,000-11,000/uL Platelets: 200,000-500,000/uL Cats WBC: 5,000-11,000/uL Platelets: 200,000-500,000/ul
What part of the spun blood in the hematocrit tube contains WBC and platelets?
The “Buffy coat”, which is the thin white band between the red blood cell and plasma layers.
How are WBC estimated on an emergency blood smear?
On 40X magnification on an area of the slide with a single layer of cells, count the number of WBC seen and multiply by 1600 to estimate total WBC count.
*Note: The WBC count will naturally be higher at the far edge of the smear, so counts at the far edge of the slide may be higher.
How are platelets estimated on an emergency blood smear?
On 100X magnification on an area of the slide with a single layer of cells, count the number of platelets seen in one high-powered field and multiply by 15,000-20,000 to identify a platelet estimate.
Causes of low WBC
- Rapid onset or early active infection consuming WBC (sepsis, pneumonia, pyometra)
- Reduced bone marrow production (parvovirus, bone marrow injury or toxicity)
Causes of high WBC
Active or chronic infection or inflammation, beyond the acute phase of rapid WBC use.
Excessive bone marrow production (bone marrow cancer)
*Note: Elevated WBC count does not always mean “infection”, and antibiotic therapy is not always indicated.
Causes of low platelets
- Consumption (active bleeding)
- Poor production (bone marrow disease)
- Destruction (immune-mediated thrombocytopenia, drugs)
- Sequestration (platelets hang out in peripheral vessels)
Causes of high platelets
Many diseases, and not usually a primary problem that needs to be addressed
What are Blood Chemistries
Measurements of parameters in a plasma or serum sample that provide information on function of various organ systems (kidneys, liver, gastrointestinal tract), proteins, and electrolyte values.
Which parameters are commonly measured cage-side for emergency management of dogs and cats?
Sodium (+/- Chloride) Potassium Calcium Glucose Urea nitrogen (BUN), +/-creatinine
At admission, when should you perform chemistry tests?
Any animal that is not completely healthy (although costs of testing should be discussed with the owner). Depending on severity of illness, tests are sometimes done as cage-side tests with immediate results, and at other times are performed by submitting blood to the laboratory for more complete results but without immediate availability of results.
With inpatient testing, when should you perform chemistry tests?
For monitoring of response to therapy or deterioration of condition. Certain medical conditions, such as diabetic ketoacidosis or Addison’s disease, may require tests to be performed multiple times a day.
Normal blood chemistry values, dogs and cats
-Dogs: Sodium (Na): 142-155 mEq/l Chloride (Cl): 112-120 mEq/l -Cats: Na: 145-158 mEq/l Cl: 115-123 mEq/l -Both: Potassium (K): 3.5-5.5 mEq/l Calcium (Ca): 9-11 mEq/dl (Ionized Ca 1.0-1.25 mmol/L) Glucose: 80-120 mg/dl BUN: 8-28 mg/dl Creatinine: 0.8-1.6 mg/dl
When does high potassium happen?
Urinary obstruction Bladder rupture and urine in the abdomen Acute kidney failure Accidental overdose Severe tissue damage (rare)
What does high potassium cause?
Irregular heart rhythm and slow heart rate, leading to heart standstill and cardiac arrest
When does low potassium happen?
Chronic kidney failure (cats)
Excessive fluid administration
Diabetic ketoacidosis
What does low potassium cause?
Muscle weakness leading to inability to lift head (cervical ventroflexion) and respiratory failure
When does high glucose happen?
- Diabetes mellitus/ diabetic ketoacidosis
- Stress (cats)
- Excessive intravenous dextrose administration
What does high glucose cause?
Increased urine output and drinking (PU/PD)
When does low glucose happen?
Puppies and kittens with poor food intake (especially toy breeds) Severe systemic infection (Sepsis) Addison’s disease (hypoadrenocorticism) Insulin overdose Liver failure (uncommon)
What does low glucose cause?
Seizures, coma, death
When does high BUN or creatine happen?
Kidney failure
Urinary obstruction or bladder rupture
Severe dehydration
What does high BUN or creatine cause?
Nausea, anorexia, vomiting, diarrhea, respiratory and brain injury
When does low calcium happen?
Dogs with poor nutrition that are nursing puppies
Parathyroid disorders
Antifreeze toxicity
What does low calcium cause?
Tetany (Muscle twitching)
Seizures
Death
When does high sodium and chloride happen?
Severe dehydration
Poor water intake
What does high sodium and chloride cause?
Excessive thirst (PD)
Dementia/ behavior change
Seizures
Coma
When does low sodium and chloride happen?
Excessive water intake
Excessive fluid loss
What does low sodium and chloride cause?
Dementia/ behavior change
Seizures
Coma
How is urine obtained?
For a sterile urine sample, urine must be collected by cystocentesis (needle inserted in the bladder) However, with a critical animal, voided or catheter –collected urine should be saved, ideally prior to any fluid being administered. Fluid therapy can change urine results.
What parameters can be determined from urine?
Pre-treatment urine specific gravity is important to understanding how to interpret kidney test results. For dogs, appropriate concentration in the face of azotemia is >1.025 USG, while for cats, appropriate USG when azotemic is >1.035-1.040. Urine dipstick testing can also be performed cage-side for emergency patients to identify glucose and/ or ketones (diabetes mellitus), blood, pH, and protein. Urine sediment evaluation can reveal crystals (for example, calcium oxalate crystals for antifreeze toxicity), or tubular casts that indicate tubular damage.
How are blood clots formed?
Following tissue injury, blood platelets in circulation travel to the site of injury, adhere to the injury, and recruit other platelets to join the fight by aggregating on the initial platelets. This forms a “platelet plug”. Once the platelet plug is formed, blood-clotting factors that are made in the liver travel to the site of the platelet plug and form a solid clot. When the injury has healed, the body dissolves the clot in a process called fibrinolysis.
How do we measure platelet numbers?
Platelet count (either in a laboratory as a part of a complete blood count (CBC) test or by performing a blood smear and counting platelets)
How is platelet function measured?
By creating a tissue injury and timing how long it takes until a blood clot forms on the surface. Blood clotting should occur within 5 minutes of injury. Tests to measure platelet function include buccal mucosal bleeding time (performed on the inside of the lip) or toenail bleeding time. The risk of either test is that if the platelets are not working, bleeding might not stop.
How are blood-clotting factors measured?
Factors are measured in the laboratory by performing a prothrombin time (PT) and activated partial thromboplastin time (aPTT). These are timed tests, and prolonged results indicate an absence of certain factors. Each of these tests provides somewhat different information about the 12 clotting factors produced by the liver.
For cage-side testing, activated clotting time (ACT) can be performed. The test is performed by filling an activated clotting time tube with whole blood immediately after sample collection. The tube must be pre-warmed, and maintained at body temperature. The tube is gently agitated and formation of a solid clot is the end point. A clot should normally form within 5 minutes. Low blood platelets will cause the test to be falsely prolonged even if clotting factors are normal.
What are clinical signs of low platelets or dysfunctional platelets?
Surface pinpoint bleeding (petechia) or paintbrush bleeding (ecchymoses)
Urinary system bleeding (blood seen in urine)
Gastrointestinal system bleeding (causes melena, or dark, tarry stool)
What are clinical signs of low clotting factors
Bleeding into body cavities (thorax, abdomen) or tissue bleeding. Sometimes this is seen by excessive bleeding following obtaining a blood sample.
What causes poor platelet function?
Aspirin therapy
Tick-borne infections
Severe kidney failure
What causes poor clotting factor function?
-Acquired disorders:
Warfarin-type rodent bait intoxication (common)
Disseminated intravascular coagulopathy (DIC – can occur with any severe illness or injury)
End-stage liver failure (rare)
-Inherited disorders:
Hemophilia (rare)
What is Colloid Osmotic Pressure (COP)
This is a measure of the osmotic force exerted by blood components (primarily albumin) in circulation.
What does measuring COP in critically ill patients provide?
Measuring this value in critically ill patients provides guidance to the clinician about prescribing intravenous colloid therapy such as Hetastarch or albumin
How is COP performed?
COP is performed either on whole blood or plasma using a device called a colloid osmometer. The only commercially produced device of this type for cage-side testing is made by Wescor (the Wescor 4420). Blood is introduced into a testing chamber that contains a semipermeable membrane. This membrane is bathed in normal saline, and the device measures the osmotic pull generated from the blood sample across the semipermeable membrane.
What are normal COP levels?
Normal COP is around 20 mmHg in dogs and 24 in cats.
What conditions cause low COP?
Any condition that causes low proteins cause low COP. Proteins can be low when they are lost through leaky blood vessels, or not produced well.
What is lactate?
Lactate is a breakdown product of glucose which is produced when tissue oxygenation is poor.
What are common conditions in which lactate is high?
Common conditions in which lactate is high include any cause of shock, heart failure, gastric dilatation and volvulus (GDV), thrombosis, and trauma
Why do we measure lactate?
If lactate remains elevated when animals are treated for conditions that cause high lactate, persistent elevation can indicate persistent tissue injury and a failure to correct the underlying disorder. Studies have been performed to link persistent lactate elevations with poor prognosis which can aid in owner discussion about severity of disease.
How is lactate measured?
Most commonly, practices use a small hand-held lactate meter that requires a drop of blood for measurement. Certain blood gas and chemistry analyzers can also assess for lactate.
Whats normal lactate levels?
Normal lactate is generally < 2.5 mmol/L
What is Pulse Oximetry (SpO2)
A noninvasive method of measuring oxygen content of
arterial blood that is attached to hemoglobin.
What two forms of hemoglobin do pulse oximeters measure?
oxyhemoglobin and deoxyhemoglobin
How do pulse oximeters work and what do they calculate?
Pulse oximeters use red and infrared light emitted from a probe to measure two forms of hemoglobin and calculates the difference of these to determine oxygen content.
What must the probe in the pulse oximeter be able to calculate to be able to read a value?
Pulsate flow
When is pulse oximetry indicated?
Pulse oximetry is indicated in any patient at risk of hypoxia, including those with fast or slow respiratory rate, under anesthesia, receiving oxygen therapy, or critically ill.
What are the two types of probes on a pulse oximeter?
Transmittance probe and Reflectance probe
What is a transmittance probe?
Light shines from one side of the probe and is received by the photodetector on opposite side.
Where are transmittance probes usually attatched?
Probes are typically attached to non-haired, non-pigmented areas, to include the tongue, lip, ear, prepuce or vulva, toe web, or skin fold.
What is a reflectance probe?
Light shines from the probe, and is reflected off of a hard tissue back to the photoreceptor on the probe.
Where can a reflectance probe be attached?
This probe can be used on the ventral tail surface.
How can you tell if the pulse oximeter is accurately detecting pulsatile flow?
The signal strength is displayed as a bar or wave form, and the device also displays a heart rate. The signal strength must remain strong and pulse rate match a manual pulse rate or heart rate of the patient. If either the signal is weak or the heart rate value is inaccurate, the results cannot be trusted.
What is a normal SpO2 reading?
For a patient breathing room air, normal SpO2 should be 97% - 100%.
What does an SpO2 level below 94% indicate?
insufficient oxygenation
What does an SpO2 below 90% indicate?
severe hypoxemia
What interferes with obtaining a pulse oximetry reading?
Patient motion Poor perfusion causing poor pulse quality Severe anemia Light interference with probe Pigmented or haired skin
When is pulse oximetry falsely elevated?
In situations of abnormal hemoglobin. SpO2 will be falsely elevated when there is excessive carboxyhemoglobin or methemoglobin.
What is carboxyhemoglobin?
carbon monoxide toxicity
What is methemoglobin?
acetaminophen toxicity in cats.
What is End-Tidal CO2 (ETCO2)
(also called capnometry)?
A noninvasive measurement that estimates partial pressure of carbon dioxide (PaCO2). Carbon dioxide is the primary monitoring tool for ventilation, making ETCO2 valuable in patients under general anesthesia or receiving mechanical ventilation.
When is ETCO2 indicated?
- Monitoring ventilation in anesthetized or sedated, intubated animals (general anesthesia or mechanical ventilation
- Confirmation of endotracheal and feeding tube placement
- Monitoring during cardiopulmonary resuscitation
What is a capnometer?
ETCO2 monitor
What are the two types of capnometers?
Side-stream monitor and Mainstream monitor
What is a side-stream monitor?
a small tube is inserted into the endotracheal tube to sample exhaled respiratory gas
What is a mainstream monitor?
a heated sensor attachment fits between the endotracheal tube and anesthetic circuit
What problems are present with a side-stream monitor?
Sampling tube can occlude with respiratory secretions. Since they draw off a portion of gas, oxygen flow rates might need to be increased.
What problems are present with a mainstream monitor?
The heating device could cause thermal burns to respiratory mucosa with long-term use. Require time to come to appropriate temperature, and more frequent calibration. Can increase dead space in the ventilation circuit.
What is a normal ETCO2 level?
35-45 mmHg
What should the capnometer value for ETCO2 be compared to?
The capnometer value should be compared to an arterial blood gas value for PaCO2 – if the capnometer is accurate, the ETCO2 should be 2-5 mmHg lower than PaCO2.
What does an elevated ETCO2 indicate?
hypoventilation (common) or increased metabolic activity and CO2 production (rare)
What does a low ETCO2 indicate?
hyperventilation (common), or reduced metabolic activity (rare).
What can a sudden decrease towards zero in ETCO2 levels indicate?
disconnection of respiratory circuit, airway obstruction, or death.
What information does a blood gas analysis provide?
valuable information about the metabolic and respiratory status of patients presenting to the veterinary emergency room.
What is a normal pH range in the body?
7.35-7.45
How does the body maintain pH?
a combination of kidney function, buffers in the blood, and respiratory function
What is it called when pH decreases?
academia (too much hydrogen)
What is it called when pH increases?
alkalemia (not enough hydrogen)
What is the only way that a blood oxygen level is obtained?
an arterial sample
What are some common sites for arterial blood gas sampling?
dorsal pedal artery or the femoral artery
What must happen to blood before being introduced into the blood gas machine.
Blood must be anti-coagulated, typically with heparin, since blood clots will cause malfunction of the device.
What values are important for the blood gas analysis?
pH, bicarbonate (HCO3-), partial pressure of carbon dioxide (PCO2), and partial pressure of oxygen (PO2)
Normal HCO3- levels?
18-24
What are normal PaCO2 or PvCO2 levels?
35-45
Normal PaO2 in room air (21% oxygen)
80-100
What are bicarbonate (HCO3) abnormalities consistent with?
a metabolic origin of a blood gas disorder or attempt to correct a primary respiratory disorder
What are PCO2 abnormalities consistent with?
with a respiratory origin of a blood gas disorder or attempt to correct a primary metabolic disorder.
If pH is low and there is a concurrent low HCO3-…
Metabolic acidosis
If pH is low and concurrent PCO2 is high…
Respiratory acidosis
If pH is high and concurrent HCO3- is high…
Metabolic alkalosis
If pH is high and concurrent PCO2 is low…
Respiratory alkalosis
Causes of metabolic acidosis?
- Shock, dehydration (Lactic acidosis)
- Renal failure
- Antifreeze toxicity (Ethylene glycol)
- Diabetic ketoacidosis
- Renal tubular acidosis (rare)
- Severe diarrhea (rare)
- Compensation for respiratory alkalosis (rare)
Corrections for metabolic acidosis?
- Correct underlying disorder
- Consider intravenous sodium bicarbonate if severe and animal is breathing
Causes for metabolic alkalosis
- Severe vomiting and dehydration
- Excessive administration of bicarbonate
- Compensation for respiratory acidosis (rare)
Corrections for metabolic alkalosis?
-Correct underlying disorder
-Fluid therapy with IV 0.9% NaCl.
Administration of gastric acid reducers
Causes of respiratory acidosis?
- Hypoventilation
- Deep anesthesia
- Muscle weakness
- Airway obstruction
- Brain disease
- Cervical spinal cord disease
- Inadequate mechanical ventilation
- Compensation for metabolic alkalosis (uncommon)
Corrections for respiratory acidosis?
- Reduce depth of anesthesia
- Correct airway obstruction
- Alter mechanical ventilation parameters
- Correct neurologic disease if possible
Causes of respiratory alkalosis?
- Hyperventilation
- Stress, anxiety, fear, pain, excitement, brain disease
- Compensation for metabolic acidosis (common)
Corrections of respiratory alkalosis?
Administer analgesia, reduce anxiety
How should urine be collected?
cystocentesis
What is cystocentesis?
needle in the bladder
What are the ways that a urinalysis can be done?
urine that is voided, collected by catheter, or by cystocentesis
What is the normal urine specific gravity (USG)?
1.000 – 1.080 depending on fluid balance in the body
In a dehydrated dog, what is an adequate concentration in the urine?
~1.025
In a dehydrated cat, what is an adequate concentration in the urine?
~1.035-1.040
What is a foley catheter used for?
- Female dogs
- +/- male dogs (catheter diameter / length limit use)
- Cat urethra generally too small for this catheter
How does a foley catheter work?
- Place catheter through urethra into bladder and inflate balloon (valve prevents deflation when insufflation syringe removed)
- Balloon keeps catheter in the bladder
What is the red rubber catheter used for?
- Male dogs (must use correct length)
- Can use in female dogs – Foley is preferred
- Male cats (3.5 Fr) for indwelling
How do you suture the red rubber catheter to the skin for indwelling?
Place tape “butterfly” around catheter and suture that to skin
What are the two types of feline catheters?
Tomcat and slippery sam
What is a feline catheter?
- 3.5 French diameter
- Male cats and female cats
- Useful for unblocking
Is a tomcat catheter meant for indwelling?
No
What is a closed system urine collection?
- One-way flow
* More costly
What is an open system urine collection?
- 10 mL drip set and empty fluid bag • Widely used in vet med
- Important to maintain sterility
What is an indwelling catheter?
A catheter that stays in. Clean exposed parts of indwelling catheters 3-4 times a day with chlorohexidine.
How should you measure urine output volume?
with gram scale rather than volumetric (1gram=1mL)
Anuria
No urine output measurable
Oliguria
Insufficient urine quantity = ~ 0.25 mL-0.5
mL/kg/hour
What is a normal urine output?
~1-2 mL/kg/hour
Polyuria
> 2 mL/kg/hr
