Shock1; articles cards 26-41

Question 1

Calculate volume needed for blood transfusion?

Answer 1

Bloodneeded(ml)=
weight(kg)xDesiredPCV−RecipientPCV
_______________________
Donor’sPCV

Then multiply that number ×70(cat)or90(dog)*

Note: A rough estimate is 2.2ml of blood/kg of body weight increases the recipient’s PCV by 1%.

Question 2

FAST (Focused Assessment With Sonography for Trauma) Protocol to Detect Free Abdominal Fluid in Dogs
Uses two ultrasonographic views (transverse and longitudinal) for what four regions of the abdomen?
Also included is the conclusion made by Lisciandro jvecc 2009

Answer 2

1Subxiphoid region
2Midline position over the bladder
3Right flank in right and left lateral recumbency, caudal to ribs
4Left flank in left and right lateral recumbency, caudal to ribs
Lisciandro 09: Initial and serial AFAST (A=abdominal) with applied AFS (abdominal fluid scoring) allowed rapid, semiquantitative measure of free abdominal fluid in traumatized patients, was clinically associated with severity of injury, and reliably guided clinical management. Where possible, AFAST and AFS should be applied to the management of blunt trauma cases.

Question 3

Shock dose for animal with severe pulmonary, cardiac, or renal dz?

Answer 3

one-quarter to one-half the calculated shock dose is administered over 15 to 30 minutes, and the patient is carefully reassessed for changes in vital signs.

Question 4

Oxygen delivery equation? DO2 = …

Answer 4

DO2 = CO x CaO2

Question 5

Cardiogenic shock?

Answer 5

results from inability of heart to propel blood through circulation; can be interference with diastolic filling or with the ability to pump (systolic failure). Also can be extracardiac like compression of heart or great vessels by some other pathology (sometimes referred to as obstructive shock as its own category)

Question 6

hypovolemic shock?

Answer 6

inadequate circulating volume causing decreased preload, thus reduced CO

Question 7

Distributive shock?

Answer 7

impairment of the mechanisms regulating vascular tone, with maldistribution of the vascular volume and massive systemic vasodilation. Decreased systemic vascular resistance causes “relative” hypovolemia and reduction in venous return. (ie sepsis, SIRS, anaphylactic reactions, or neurogenic shock caused by severe damage to CNS with loss of autonomic stimulation on vessels.

Question 8

Hypoxic Shock?

Answer 8

inadequate arterial oxygen content of cellular oxygen utilization. Most common causes are anemia (reduced hemoglobin concentration–anemic hypoxia), and hypoxemia associated with respiratory failure

Question 9

Equation for cardiac output….CO = …?

Answer 9

CO = SV x HR

Question 10

3 factors that determine stroke volume (SV)?

Answer 10

preload, afterload, and contractility

Question 11

Preload?

Answer 11

Load imposed on a resting muscle to stretch it to a new length. Preload = End Diastolic Volume; An increase in End Diastolic Volume augments the strength of cardiac contractions (Frank-Starling mechanism). Factors that influence preload: splenic contraction, retention of Na and H2O, and increased thirst

Question 12

Afterload?

Answer 12

The force that opposes muscle contraction, and in cardiac muscle, it is equivalent to the ventricular wall tension developed during systole. Afterload= “pressure in the left ventricle required to eject blood into systemic circulation”

Question 13

Afterload is influence mainly by ___ ____ ____.

Answer 13

systemic vascular resistance. Low BP is the major determinant of decreased afterload.

Question 14

Contractility?

Answer 14

the force and velocity of cardiac muscle contraction

Question 15

Arterial Oxygen Content (CaO2) Equation?

Answer 15

CaO2 = Hb x SaO2 x 1.34 + PaO2 x 0.003*
Thus, oxygen content depends mainly on Hb concentration and oxygen saturation of Hb in arterial blood (SaO2; measured as %).
(*oxygen solubility coefficient)

Question 16

SaO2 is the percentage of available hemoglobin that is bound to ____?

Answer 16

oxygen

Question 17

Hb affinity for oxygen increases as oxygen saturation of Hb increases. Thus the oxygen-hemoglobin dissociation curve, which relates Hb saturation of O2 to the partial pressure of O2 (PaO2), is a _______curve.

Answer 17

sigmoidal

Question 18

What are the 4 factors that influence Hb affinity for O2?

Answer 18

pH, temperature, 2,3-DPG (diphosphoglycerate), and CO2 that can cause a shift in the dissociation curve (ie - making O2 more or less readily released in tissues.

Question 19

For a normal O2 tension of ___ to ___ mm Hg, the Hb saturation is 100%.

Answer 19

90-100 mm Hg

Question 20

Describe whether an increase or decrease in each of the factors below causes the O2 disassociation curve to shift to the LEFT (ie. delivery of LESS Oxygen).
pH:
temp: 
2,3 DPG:
CO2:

Answer 20

Shift to the LEFT
(ie. delivery of LESS Oxygen).
pH: Increase
temp: Decrease
2,3 DPG: Decrease
CO2: Decrease
(Note that pH is the only factor that causes a LEFT shift when it is INCREASED)

Question 21

According to the American College of Surgeons hemorrhage classification system (Box 6-2), loss of ___________ % of circulating blood volume is able to trigger shock, and loss of more than ___________ % of circulating blood volume, if left untreated, induces irreversible shock.

Answer 21

30-40% triggers shock; 40% - irreversible shock

Question 22

Catecholamine-resistant vasodilatory shock is characterized by refractory hypotension despite intravascular fluid resuscitation and catecholamine administration. Catecholamine-resistant vasodilation is caused by derangements of normal vasodilatory and vasoconstrictor mechanisms, and occurs despite increased levels of norepinephrine, endothelin, and angiotensin II. Author Silverstein (jvecc 2012) found that in dogs with vasodilatory shock that were nonresponsive to dopamine that this drug was effective at increasing blood pressure.

Answer 22

Silverstein found that exogenous
AVP can act as a potent vasoconstrictor in dogs with refractory vasodilatory shock.
AVP = Arginine Vasopressin, aka antidiuretic hormone.

Question 23

What is AVP aka ADH? Made? Stored?

When is it normally released?

Answer 23

AVP is a potent vasoconstrictor peptide, synthesized in the hypothalamus and stored in the posterior pituitary. Normally, it is released into the circulation in response to an increase in the serum osmolality (sensed in the brain) or a reduction in plasma volume (sensed by baroreceptors in the left atrium, aortic arch, and carotid sinus)

Question 24

MOA of AVP (arginine vasopressin)

Answer 24

The cellular effects of AVP are mediated by interactions
of the hormone with 2 principal types of receptors:
V1 and V2. V1 receptors, previously known
as V1a receptors, are predominantly located in the gastrointestinal tract and vascular smooth muscle, and
these receptors primarily mediate the vasoconstrictive
response to the hormone. In addition, when present in
high concentrations, AVP causes the HR-arterial pressure
baroreflex curve to shift leftwards by interacting
with V1 receptors in the brain. In contrast, V2 receptors
are primarily found in the principal cells of the
renal cortical and medullary collecting ducts, and these
receptors primarily mediate the antidiuretic effects of
the hormone. AVP also blunts the accelerated synthesis
of nitric oxide following LPS and IL-1b stimulation
in sepsis, and also reduces the vasodilatory effects of
nitric oxide, thereby preventing the nitric oxide-mediated
vasodilation that occurs in sepsis

Question 25

What are the primary causes of inappropriate vasodilation?

Answer 25

Elevated levels of nitric oxide and activation of the smooth muscle ATP-sensitive potassium (KATP) channels
and calcium-regulated potassium channels (KCa2þ ) are the primary causes of the inappropriate vasodilation, but the lack of reflex vasoconstriction is not as
clearly understood. Other potential contributors to vasoplegia include fatal injuries to the vascular endothelial
cells from prolonged hypotension, inadequate oxygen extraction from the tissues, and an increase in the activity of vasodilatory prostaglandins.

Question 26

In Silverstein’s case series of 5 dogs with refractory vasodilatory hypotension that responded to AVP, what was the dose range that she used?

Answer 26

Starting dose: 0.5 mU/kg/min; Their doses were titrated up to maximum doses of 1 and 5 mU/kg/min, however the dog that
was given 5 mU/kg/min of AVP had shown an a positive response to 1.25 mU/kg/min until an acute episode of vomiting and aspiration occurred, after which the dog experienced respiratory arrest and needed the higher dose

Question 27

Author Shih, jvecc 2010, evaluated the accuracy and precision of oscillometric noninvasive BP as a predictor of invasive direct BP in healthy, anesthetized, hypotensive and normotensive dogs. Prospective study, 8 dogs. Art lines used to measure direct BP. To make them hypotensive, dogs were maintained on iso while withdrawing ~ 40% of the animal’s blood volume until aMAP was stable at approximately 40mmHg. What was their conclusion?

Answer 27

The oscillimetric device was not reliably predictive of intra-arterial BP during hypotension associated with hemorrhage

Question 28

Author Shih, jvecc 2010: Was the non-invasive BP more frequently falsely higher or lower than direct BP? Was this difference more substantial during hypotension or normotension?

Answer 28

NIBP more frequently read higher than direct BP.
NIBP device greatly overestimated BP measurements, particularily when hypotension was present. Some readings during hypotension (~18.7 %) had a bias of > 30%

Question 29

Shih, jvecc 2010: The data generated in this study suggests that if a patient has an nSAP reading of 70mmHg, then 95% of simultaneously
collected dorsal pedal intra-arterial measurements would range from ___mm Hg to ___mm Hg.

Answer 29

40 to 110mmHg.

Question 30

Acierno javma 2010: Agreement between directly measured blood pressure and pressures obtained with three veterinary-specific oscillometric units in cats: 21 cats:
How many of the 3 units were found to agree with the direct BP?

Answer 30

None. For all 3 veterinary-specific oscillometric units examined
in the present study, agreement between indirectly and directly measured blood pressures was poor. These findings suggested that none of the units could be
recommended for indirect measurement of blood pressure in cats.

Question 31

In this Acierno paper, they followed a guideline of choosing a BP cuff with a width that was __% to __% of the limb circumference

Answer 31

30 to 35 % (Acierno javma 2010 study)

FYI, Bosiack, jvecc 2010, study (next card) used 40% of limb circumference

Question 32

Bosiack jvecc 2010.
Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure measurements in ill dogs;
FYI, NIBP devices: doppler-DOP and 2 oscillometric BP monitors, (CAR-cardell and PAS-datascope passport).
Fill in the blank with overestimated or underestimated.
Within the hypotensive group, each indirect method _______ the corresponding IBP.
(underestimated or overestimated)
measurements

Answer 32

Within the hypotensive group, each indirect method overestimate the corresponding IBP.

Question 33

Bosiack jvecc 2010;
Fill in the blank with overestimated or underestimated.
Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements_______ the corresponding IBP. The remaining indirect measurements ________ the corresponding IBP.

Answer 33

Within the normotensive group all indirect systolic measurements and the PAS diastolic measurements underestimated
the corresponding IBP. The remaining indirect measurements overestimated the corresponding IBP

Question 34

Bosiack jvecc 2010. Fill in the blank with overestimated or underestimated.
Within the hypertensive group, DOP and CAR systolic measurements __________ the corresponding IBP, and the remaining indirect measurements ___________ the corresponding IBP.

Answer 34

Within the hypertensive group, DOP and CAR systolic measurements underestimated the corresponding IBP, and the remaining indirect measurements overestimated the corresponding IBP.

Question 35

Bosiack jvecc 2010;

All indirect measurements were most accurate in dogs that were (hypotensive/normotensive/hypertensive) ???

Answer 35

All indirect measurements were most accurate in hypertensive dogs.

Question 36

Bosiack jvecc 2010.

In hypertensive dogs oscillometric (diastolic? or systolic?) measurements were more accurate than MAP.

Answer 36

In hypertensive dogs oscillometric (diastolic? or systolic?) measurements were more accurate than MAP. Conclusions – The noninvasive blood pressure monitors in our study did not meet the validation standards set in human medicine. However, CAR diastolic and MAP measurements within the normotensive group,
CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were
close to these standards. All indirect measurements showed greater bias during hypotension. Precision was
poorer for all indirect systolic measurements than for MAP.

Question 37

Bosiack jvecc 2010. None of the 3 devices met the standards set for humans, but which ones came the closest? Name device used and the specific measurement (ie diastolic, MAP, or systolic) and the group (ie hypo/normo/hyper tensive group?)
Hint: There were two measurements within the normotensive group, one measurement within the hypertensive group, and one measurement in all groups were close to these standards (ie 6 total)

Answer 37

CAR diastolic and MAP measurements within the normotensive group,
CAR MAP measurements within the hypertensive group, and PAS diastolic measurements in all groups were
close to these standards.

Question 38

Bosiack jvecc 2010. Which device’s MAP measurements were the most accurate of all NIBP measurements taken?

Answer 38

The CAR MAP measurements were the most accurate of all NIBP measurements taken.

Question 39

Bosiack jvecc 2010.The data of the present study suggests that at direct MAP ___mmHg NIBP measurements overestimate direct measurements. This finding may suggest
that when making therapeutic decisions based on NIBP measurements, clinicians may not be detecting and therefore treating hypotension as often as it occurs

Answer 39

80 mm Hg

Question 40

Bosiack jvecc 2010. Precision was poorer for all indirect ________ (systolic or diastolic?) measurements than for MAP (ie which specific measurement resulted in a larger range of values (poor precision) than the MAP.

Answer 40

Precision was poorer for all indirect systolic measurements than for MAP.

Question 41

Bosiack jvecc 2010. In hypotensive dogs _____(systolic, MAP, diastolic) measurements were more accurate than _____(systolic, MAP, diastolic) measurements.

Answer 41

In hypotensive dogs MAP measurements were more accurate than systolic measurements