HYPOVOLEMIC SHOCKBy: Abigail Schmidt

What is shock?

Shock is a syndrome that is the clinical result of oxygen delivery insufficiency to the cell requirements of the body

Hypovolemic

Absolute: loss of blood volume or fluid

Relative: cardiogenic problem or venous obstruction

OR

Hyperdynamic

Most common in septic animals

HYPOVOLEMIC SHOCK

Most common type

Inadequate circulating volume to deliver oxygen effectively to tissues

Loss of intravascular volume

Dehydration i.e. vomiting

Blood loss i.e. splenic rupture

3rd spacing of fluids i.e. into distended stomach

Signs of Hypovolemic Shock

Compensatory events take place:

Tachycardia (low preload = reduces cardiac output)

Peripheral vasoconstriction

Hypotension

Decreased perfusion to essential organs, development of acidosis

Primary Clinical Signs

Pale MMs

Prolonged CRT

Tachycardia

Tachypnea

Cool extremities

Poor peripheral pulses

(bounding in early stage)

Triage Primary Assessment ABCD:

AB: Airway & Breathing

Is P breathing? Is airway patent?

Is P working too hard to breathe?

C: Circulation

Is heart beating effectively?

ASSESS FOR SHOCK

MM/CRT, BP, Pulse Assessment

D: Debilitating Disease

Neuro assessment

Minimum BW: renal parameters, PCV/TP, ALT, Glucose, E-lytes

Triage 2

Secondary Survey

Respiratory

RR, RE, MM, URT (inspiratory) vs LRT (expiratory)

LOCALIZE

Cardiovascular

Arrhythmias, tissue perfusion (BP, lactate, CRT, MM)

SHOCK

Neurological

Abdominal

VITAL 1st STEPS

Necessary to increase tissue perfusion via fluids

NEED to exclude:

Heart disease

Respiratory disease

Intracranial disease

BEFORE loading patient with shock-dose rate fluids

Heart Disease

Failure of pump, caused by:

Heart disease

Cardiac tamponade

Arrhythmias

Thoracic auscultation

Murmurs

Pulmonary edema heard as crackles

Ascites/Jugular distension

Large volume fluid administration contraindicated!!!

Respiratory Disease

Tachypnea/Dyspnea with increased sounds heard on auscultation Crackles, wheezes, etc.

ALTERNATIVELY: dullness indicates pleural effusion, another contraindication to shock fluids

Altered mentation/increased ICP Neurologic signs

Seizures, Blindness, Absent PLR, Incoordination etc.

Intracranial Disease

Low BP activation of sympathetic nervous system Tachycardia Peripheral Vasoconstriction Fluid retention

Protective response may make patients seem more stable than what they truly are.

Pathological Consequences

In attempt to maintain BP and perfusion

What to do BEFORE referring

Check important parameters: HR, BP, temperature

BP may initially be normal due to sympathetic NS Then decline/drop low

MM, CRT, Pulse rate/quality, RR

Cats vs. Dogs Dogs: bradycardia

worsening “shock” state = worse prognosis

Cats often don’t present tachycardic (less scary) Cats more susceptible to fluid overload

Monitor respiratory rate/effort!

Cats more prone to hypothermia active warming

Circulatory & Hypovolemic Shock

Clinical Sign Vasodilatory VasoconstrictoryMild/ Moderate Severe/ Compensated Decompensated

Heart rate 130-150 150-170 170-200, may become bradycardic

Pulse strengthBounding (due to dilated blood vessels)

Weak becoming absent.. …

Mm colour Bright red (hyperemic) Pink to Pale becoming.. White/grey

CRT <1sec (blood pooling in vessels)

~2 seconds >2 seconds

Temperature of Extremities

Warm (vasodilation)Cooler (vasoconstriction)

Cool

Metatarsal pulse palpable

Easily Just Absent

WHY give Fluids for Hypovolemic Shock

- Lack of perfusion can kill animals quickly

OR

- Shock consequences can cause significant mortality in the days following insult/injury

Cellular Hypoxia

Free radical generation

Inflammatory Mediators

SIRS MODS DIC

Systemic Inflammatory Response Syndrome Inflammatory mediators cause disruption of

homeostasis Loss of vascular tone

Endothelial permeability barrier disruption

Stimulation of coagulation

Microvascular thrombosis resulting in…

Multiple Organ Dysfunction Syndrome

Disseminated Intravascular Coagulation IV activation of coagulation with loss of localization

DIC aka

Shock Treatment Aims

Provide oxygen support

Connect to appropriate monitoring

Vascular access and BP

Shock fluid boluses to restore vascular perfusion and oxygen delivery to tissues

Pain medications if needed

Stabilize the patient and send to IndyVet!

Isotonic Crystalloidsi.e. Hartmann’s aka LRS,

0.9% Sodium Chloride

Same concentration of solutes as blood; same osmotic pressure

Small molecules freely pass out of BVs, able to enter all body compartments 1/5 of total volume given = actually remain in BVs

1-2 hrs later

Crystalloids 2

“Shock doses” = 60-90 ml/kg, but given in incremental boluses delivered over 15-20 min

Assess P after each bolus; repeat if necessary

**Rapid expansion of blood volume with crystalloids may worsen blood loss

**Risk of interstitial edema, dilution of RBCsand clotting factors with repeated boluses

Colloids i.e. Hetastarch, Dextran 70

Large molecules which do NOT pass out of BVs

Expand IV space by increasing oncotic pressure

“Shock doses” = 20 ml/kg

Given as boluses of 5-10 ml/kg

Cons

Synthetic can cause acquired coagulopathy

Expensive, not multi-purpose

Pros

Less volume needed

Useful with large Ps

IV expansion lasts longer (up to 12 hrs)

Hypertonic Saline i.e. 7% NaCl

Rapid expansion of IV compartment Draws H2O into vascular space from interstitial

compartment, endothelial cells, and RBCs “Shock dose” = 4-7ml/kg of 7% hypertonic saline

Given over 20 min

Cons Short-acting, benefits last

<1 hr Administration may result

in bradycardia & arrhythmias

CANNOT BE USED if P is dehydrated or has marked electrolyte disturbances

Pros Small volumes needed

CV function improvements

Myocardial contraction,

Head trauma, penetrating wounds, reduces inflammation

Blood Products NOT the 1st line of treatment for

shock Can’t be given fast enough Risk transfusion reactions

Animals in shock don’t die of anemia They die of LACK of vascular volume

Transfusion may be needed after initial resuscitation to keep HCT > 20-25%

***Expensive

Pain Medications

Avoid NSAIDs Opioids *critically ill patient

Torb (Butorphanol) – 0.1-0.5 mg/kg, IV, IM, SC q 2-6 hrs

Buprenex (Buprenorphine) – 0.005-0.02 mg/kg, IV, IM, SC q 4-12 hrs

Hydromorphone – 0.05 to 0.2 mg/kg,IV, IM q 1-4 hrs

Injectable, varying effects (partial vs. full agonist) Partials better for respiratory compromised Reversible with Naloxone

Questions?