Fluids 5: Fluids for Hypovolemia and Shock: Lesson 48

Fluids for shock: large animals

80-90 ml/kg, fluid BOLUS ¼ of this volume

Shock dose: small animals

Cats, a fluid bolus is 5-10 ml/kg

Dogs, a fluid bolus is 15-20 ml/kg

Shock official definition

Life threatening, generalized maldistribution of blood flow resulting in failure to deliver and/or utilize adequate amounts of oxygen, leading to tissue dysoxia

Clinical signs of shock

A syndrome characterized by severe clinical signs and abnormalities in perfusion

Cellular Level Pathophysiology of shock

Shock → hypoxia

Hypoxia → switch from aerobic to anaerobic metabolism → 2 lactate + 2 ATP

hypoxia-induced cell damage and organ failure in shock

6 “core” perfusion parameters

Mentation, HR, Pulse quality, MM color, CRT, Rectal and distal extremities temperature + Blood pressure, Urine output, lactate and more

Many classifications of shock: patient may have multiple at one time

Cardiogenic shock

Hypovolemic shock

Distributive shock

Obstructive shock

Large Animals: Example

Weight: 425 kg

Horse fluid bolus = 1/4 of “shock dose”

Shock dose is 80-90 ml/kg, Let’s calculate 90 ml/kg

425 kg X 90 ml/kg = 38,250 ml, Convert to L → 38.25 L

Give 1/4 as a bolus: 38.25 ÷ 4 = 9.5 L

Give 9.5 L isotonic crystalloid IV fast

Cats: Example

Weight: 4 kg

Cat fluid bolus = 5-10 ml/kg

Let’s calculate 10 ml/kg: 4 kg X 10 ml/kg = 40 ml

Give 40 ml isotonic crystalloid IV over 15 mins

Treatment of Hypovolemic Shock: How fast?

FAST: Each bolus over 10–15 minutes

treatment of hypovolemic shock: How much?

Reassess after each bolus

If shock signs persist → give another bolus

Treatment of hypovolemic shock: When do we stop?

Goal-directed therapy

Stop when perfusion parameters normalize

Treatment of hypovolemic shock: important

Early resuscitation rarely causes immediate edema or effusion

Fluid overload signs develop later

If >2–3 boluses are needed → consider other types of shock

usually start with balanced crystalloid

Monitoring fluid therapy

Hypertonic saline

RAPID volume expansion, pulls fluid from interstitial space to intravascular → after using for volume expansion, will have to “pay it back” with isotonic crystalloid (IV or PO)

Dose: 2-4 ml/kg IV

Colloids for Treating Shock

Plasma or synthetic colloids can be used for shock: Dose= 5-10 ml/kg IV over 15 mins

Whole blood or packed red blood cells – for hemorrhagic shock

if crystalloid boluses are attempted and patient is still showing signs of hypovolemia or patient needs oncotic support(colloids)

What should you do next after giving the hypertonic solution IV?

Isotonic crystalloid in gold standard

Give oral fluids in field, actual practice