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?