Foundations - Exam 1

Hyperemia

Excess of blood contained within blood vessels in a part of the body due to an active process

Hyperemia - gross apperance

Inflammation, pulse may be felt readily
Not seen postmortem

Hyperemia - causes

Physiologic - in response to increased demands for nutrients because of work being done
Pathologic - in response to certain vasodilator chemicals and neurogenic stimuli associated with irritation of tissue

Hyperemia - effects

hastens movement of metabolites into area and flushing of catabolites from the area

Congestion

An excess of blood contained within blood vessels in a part of the body due to a passive process

Congestion - gross apperance

dark blue/red tinge, swollen, cooler than normal, if chronic tissue may have a brown color
After death it may become even more dark blue

Congestion - causes

Peripheral - obstructive (Thrombus), Constrictive (vein collapse due to outside pressure)
Central - heart failure
Hypostatic - when an animal is recumbent for a long period and gravity pulls on blood

Heart Failure is caused by (3)

Weakened ventricular muscle
increased resistance when Ventricles are pumping (hypertension)
Increased volume of blood delivered to ventricles (leaky valves, septal defects)

Congestion - effects

Hypoxia and accumulation of catabolites in the tissue that leads to edema, necrosis, thrombosis, proliferation of connective tissue if chronic

Petechiae

Diapedesis - less than 2mm

Ecchymoses

diapedesis - 220mm

Purpura

Confluent multiple petechial/ecchymotic hemorrhages

hemorrhage per diapedesis - causes

hypoxia, anoxia, toxic injury, vasculitis, nutritional deficiency, abnormal coagulation of blood

Hemorrhage per rhexis - causes

Trauma, vessel wall necrosis, vessel wall invasion by neoplasia, primary vascular disease

When is hemorrhage deadly or cause shock

¼ to 1/3 of total blood volume over a period of less than a few hours

Epistaxis

blood from nares

hemarthosis

blood in joint

hemothorax

blood in thorax

Hemoperitoneum

blood in the abdominal cavity

Hemosalpinx

blood in a tube, usually refers to oviduct

Hypema

Blood in the anterior chamber of the eye

Hemoptysis

coughing up blood

Hematemesis

vomiting blood

Hematochezia

presence of red blood in stool

Melena

tarry blood in stool

Components of Anesthesia (5)

Unconsciousness
Muscle relaxation/immobility
Amnesia
Attenuation of autonomic reflexes
Analgesia

Cardiovascular complications with anesthesia

Arrhythmias, circulatory failure, myocardial depression

Respiratory complications with anestheisa

Hypoventialation, apnea, bronchoconstriciton, airway obstruciton, pulmonary thromboemolism

Annesthesia risk factors (7)

Old age, high ASA, urgent/emergent procdure or at night, very small size, endotracheal intubation in cats, pulse oximeter not used

ASA 1-5

ASA 1 - healthy
ASA 2 - mild systemic disease
ASA 3 - severe systemic disease
ASA 4 - severe systemic disease that is a constant threat to life
ASA 5- moribund P not expected to survive 1 day with or without Sx

What blood work does my P need for annesthesia if they had a normal PE

PCV/TS only

What blood work does my P need for annesthsia if they had an abnormal PE

CBC/Chem/UA

Purpose for fasting under anesthesia

Stop regurgiation/vomtiing, beter ventilation, clearer operative feild

How long to fast cats/dogs for annesthesia?

6 hours

How long to fast ruminats for anesthesia

24 hours

What problems should be resolved before going under anesthesia

Dehydration, electrolyte abnormalitites, heart failure, anemia, respiratory distress

Edema - Gross Appearance

Fluid in body cavities and/or by soft doughy, usually cool and non-painful tissue distention that pits on pressure

Transudates

accumulation of fluid due to a hydrostatic imbalance between intravascular and extravascular comparments despite normal vascular permeability

Exudates

Accumulation of fluid due to increased vascular permeability

Is transudates or exudates worse and why

Exudates is much worse due to bad stuff hitting the walls of vessels, inflammation

4 major causes of edema

increased hydrostatic pressure
Increased vascular permeability
Decreased intravascular oncotic pressure (hypoproteinemia)
Lymphatic obstruction

Anasarca

general edema
Commonly only used for fetuses that have whole body edema

Two causes of Transudate

increased vascular pressure or decreased colloid osmotic pressure

Transudate characteristics

Colorless, low [protein], low fibriogen and few cells

Exudate characteristics

more protein including fibrinogen, generally opaque, often amber, numerous cells, especially leukocytes

What causes exudates

infectious agents, toxins either directly damaging vessels or cause tissue to produce chemical signalt that alter vascualr permeability

Edema is removed primarily by

lymphatic vessels

Persistent edema can stimulate

fibrosis

Shock

failure of the circulatory system to adequately perfuse vital organs

Types of Shock

Hypovolemic - loss of blood volume
Cardiogenic - cardiac pump failure
Distrubutive or vasogenic shock - venous pooling of blood that cuases funcitonal hypovolemia (sepsis, anaphylaxis)

Body response to shock

Increased cardiac output by increase HR and contractility
Increased BP through vasoconstriction
Immediate efforts to conserve body water

Shock is characterized by

low blood flow and hypotension

Examples of cardiogenic shock

Myocarditis, myocardial degneration, cardiac tamponade, electrolyte imblances, valvular insuffiecnecy

How does sepsis cause shock

Large quantities of toxin in the circulation cause marked vascular dilation and pooling of blood in capillaries and vein
(TNFa and interleukin - 1B)

How do you die from shcok

Anoxic injury to endothelial cells that increase permeability, insufficient renal and muscular perfusion result in metabolic acidosis (suppreses cardiac output), anoxic injury to myocytes

Reference intervals center on

95% of healthy individuals so 1 in 20 test in a normal individual will be outside it

Hematology analyzer - laser how does it work

Laser light scatered by a cell can be used to count, size, and measure internal components

Hematology analyzers - impedance how does it work

cells are poor conductors of electricity, cells passing through an aperature disrupt an electrical signal which allows the cells to be counted and sized

Impedance analyzer’s problem nad what is wrong with both impedance and laser

Feline platlets are large and can be counted at rbcs
platelet clumps will not be counted by any automated analyzer

RBC count, HgB, and HCT are all used to asses

RBC mass, normally will go up or down together

MCV, MCHC, MCH, RDW are all used to asses

size (MCV, RDW) and hemoblogbin content (MCHC, MCH) of RBCs

Hemoglobin concntration can see false increase when

there are things that block light transmission
Lipemia, rbc agglutinaiton, heinz bodies

Disproprotionate increase in Hgb means

RBC lysis - most commonly in vitro

MCV

Mean corpuscular volume
measures the average volume/size of erythrocytes

MCH

Mean cellular hemoglobin
Average amount of hemoglobin per RBC

MCHC

Mean cellular Hemoglobin Concentration
Average amount of hemoglobin per mass of RBCs

RDW

Red Cell Distribution Width
Statistical expression of RBC size variation (%)

Macrocytosis

RBCs larger than normal

Increased MCV (Macrocytosis) causes

Reticulocytosis (regenerative anemia, most common cause)
FeLV infection in cats
Congenital in poodles (rare)
Vitamin B12 or folate deficiency (rarely seen with macrocytosis in domestic species)
RBC aggluction and delyaed smape processing (artifact)

Decreased MCV (microcytosis)

Iron deficiency (most common cause)
Young animal
Portosystemic shunt
Asian breeds

Decreased MCH and MCHC (hypochromia)

reticulocytosis, iron deficiency (excpet in cats)

Increased MCH and MCHC

Is always an artifcact [Can’t have too much hemoglobin]

What is often increased before MCV

Red Cell Distribution width

Reticulocytes - species differences in health

Mild numbers are normal in the dog
Horses usually don’t release reticulocytes from bone marrow even with anemia
Cats usually have very few reticulocytes in health

Anemia is classified by (3)

Bone marrow response (regenerative vs non regnerative)
RBC indices (MCV, MCHC, RDW)
Underlying mechanism

How to detch bone marrow respone to anemia

Reticulocyte count (used most often)
Polychromasia on blood smear

Absolute reticulocyte count > Reference interval

Regenerative anemia

Order of domestic species reticulocytes response

Dog> Cat> Ruminant > Horse

Degree of reticulocytosis depends on

Severity of anemia, acuteness/timing of the insult (takes bone marrow 3-5 days to respond), ability of P to respond, concurrent treatment