Overview
This lecture covers hypovolemic shock, its causes, clinical presentation, and main approaches to management, including fluid resuscitation and specific treatments for underlying causes.
Causes of Hypovolemic Shock
- Hypovolemic shock results from decreased intravascular volume due to internal or external fluid losses.
- External losses: trauma, surgery, diuresis, diarrhea, vomiting, diabetes insipidus.
- Internal losses: hemorrhage, burns (fluid shift), ascites, dehydration.
Clinical Manifestations
- Decreased intravascular volume leads to decreased preload, ventricular filling, stroke volume, and cardiac output.
- These changes cause reduced tissue perfusion.
Initial Management
- Apply oxygen to meet metabolic demands.
- Begin fluid resuscitation to restore intravascular volume using crystalloids (NS, LR), colloids (albumin), or blood products.
- Use at least two large-bore IVs or an intraosseous (IO) route if necessary.
Fluid Resuscitation Details
- For blood loss, estimate the volume lost and transfuse appropriate amounts as ordered.
- Typical guideline: administer 3 mL crystalloids for every 1 mL blood loss.
- Monitor for signs of fluid overload, such as pulmonary edema or abdominal compartment syndrome.
Choice of Fluids and Complications
- Lactated Ringer’s (LR) and Normal Saline (NS) are widely available but require large volumes and risk fluid overload.
- NS may cause hypernatremia, hypokalemia, or hyperchloremic metabolic acidosis.
- Colloids (albumin 5%, 25%) rapidly expand plasma volume but are expensive, limited, and may cause heart failure.
- Blood products (plasma, PRBCs, platelets, cryoprecipitate) rapidly replace lost blood; type and crossmatch are needed, but O negative blood can be used in emergencies.
- Monitor for transfusion reactions, acute lung injury (TRALI), hemolytic reactions, and circulatory overload.
Treating Underlying Causes
- Address specific causes: antiemetics for vomiting, antidiarrheals for diarrhea, direct pressure/tourniquet for hemorrhage, emergency surgery for internal bleeding.
- Vasopressors can temporarily increase vascular tone but are used only if fluids are insufficient.
Key Terms & Definitions
- Hypovolemic shock — shock due to decreased blood or fluid volume.
- Preload — the volume of blood returning to the heart.
- Crystalloid — IV fluids like NS or LR used for fluid replacement.
- Colloid — IV solutions containing larger molecules like albumin that expand plasma volume.
- Vasopressor — medication that increases vascular tone and blood pressure.
- TRALI — transfusion-related acute lung injury.
Action Items / Next Steps
- Review clinical signs of fluid overload and transfusion reactions.
- Practice calculating fluid resuscitation needs.
- Complete assigned reading on shock management protocols.