Hypovolemic Shock
Key Points
- Hypovolemic shock is life-threatening intravascular volume depletion with inadequate tissue perfusion.
- Two pathways are emphasized: absolute hypovolemia (true fluid/blood loss) and relative hypovolemia (third-spacing/internal sequestration).
- Early cues include anxiety/mental-status change, tachycardia, falling blood pressure trend, and declining urine output.
- Treatment priorities are rapid source control, volume resuscitation, hemodynamic support, and prevention of multi-organ injury.
Pathophysiology
Loss of effective circulating volume reduces preload and cardiac output, causing cellular hypoxia. Early sympathetic compensation may preserve pressure transiently, but ongoing loss drives hypotension, lactic acidosis, and end-organ failure.
Types
| Type | Core pattern | Common examples |
|---|---|---|
| Absolute hypovolemia | True external/internal fluid or blood loss | Hemorrhage, severe vomiting/diarrhea, fistula drainage, diuresis, diabetes insipidus-related polyuria |
| Relative hypovolemia | Intravascular-to-interstitial fluid shift (third spacing) | Burns, ascites, bowel obstruction, severe pancreatitis, long-bone fracture, ruptured spleen, hemothorax, sepsis |
Clinical Manifestations
| Domain | Early pattern | Advanced pattern |
|---|---|---|
| Blood pressure | Slightly low or near normal | Low/hypotensive |
| Heart rate | Normal to mildly elevated | Marked tachycardia |
| Respiratory rate | Normal to mildly elevated | Tachypnea |
| Urine output | Normal to slightly low | Low (often ⇐30 mL/hour) |
| Perfusion/skin | Thirst, delayed refill trend | Cool clammy/pale skin, weak or absent peripheral pulses |
| Neuro status | Anxiety, mild restlessness | Confusion, depressed mentation |
Additional cues can include dry mucosa, decreased skin turgor, orthostatic hypotension, thirst, muscle cramps, chest/abdominal pain, and ileus as perfusion worsens.
Nursing Assessment
- Trend serial vital signs and mental status; trend is more predictive than a single set.
- Assess for active or occult source of volume loss.
- Monitor urine output closely and escalate persistent decline.
- Screen orthostatic hypotension safely with assisted position changes.
- Track perfusion markers: capillary refill, skin temperature, pulse quality.
- Monitor laboratory trends:
- CBC (RBC/Hgb/Hct shifts from hemoconcentration or hemodilution after resuscitation)
- BUN/creatinine elevation with renal hypoperfusion
- Lactate elevation and metabolic/lactic acidosis
- Electrolyte and glucose fluctuations during shock/resuscitation
Nursing Interventions
- Identify and stop the loss source (pressure/elevation/procedural or surgical escalation as indicated).
- Secure and maintain vascular access for rapid therapy.
- Initiate rapid isotonic crystalloid volume resuscitation (for example 0.9% saline, lactated Ringer’s) per protocol/order.
- Use colloids or blood products when clinically indicated by loss type and response pattern.
- Monitor respiratory status closely during high-rate/high-volume resuscitation to detect pulmonary edema early.
- Support hemodynamic monitoring (including MAP trend) to evaluate response.
- Use perfusion-support positioning when indicated: supine with leg elevation or passive leg raise.
- Maintain warmth and prevent worsening acidosis.
Transfusion-Related High-Risk Complications in Severe Hemorrhagic Pathways
- Hypothermia from cold blood product administration
- Dilutional coagulopathy
- Citrate toxicity causing hypocalcemia/hypomagnesemia and arrhythmia/tetany risk
- Hemolytic reaction cues (fever, flank pain, dark/red-brown urine)
Evaluation Targets
- MAP maintained at or above about 65 mmHg in invasive-monitoring pathways
- Urine output at or above 30 mL/hour
- Improving mentation, peripheral perfusion, and hemodynamic stability
- Laboratory trend stabilization (lactate, renal markers, acid-base status)
Clinical Judgment Application
Clinical Scenario
A postoperative patient with ongoing wound drainage develops tachycardia 118, BP decline from 118/72 to 92/58, cool clammy skin, and urine output 20 mL/hour.
- Recognize Cues: Falling blood pressure trend, tachycardia, low urine output, hypoperfusion skin signs.
- Analyze Cues: Ongoing intravascular loss with evolving hypovolemic shock.
- Prioritize Hypotheses: Immediate threat is progressive tissue hypoxia and organ dysfunction.
- Generate Solutions: Rapid source-control escalation, aggressive volume replacement, and hemodynamic reassessment.
- Take Action: Establish/verify access, deliver ordered fluids/blood products, monitor respiratory and perfusion response, and report deterioration.
- Evaluate Outcomes: Urine output and MAP improve, mentation stabilizes, and perfusion signs recover.
Related Concepts
- shock-overview - Stage-based framework across shock phenotypes.
- fluid-volume-deficit-hypovolemia-and-dehydration - Intravascular depletion assessment and correction context.
- transfusion-reactions-types-and-nursing-response - Blood-product safety and reaction escalation.
- metabolic-acidosis - Anaerobic metabolism and lactic-acid accumulation in advanced hypoperfusion.
- sepsis - Sepsis can trigger relative hypovolemia via capillary leak and vasodilation.
Self-Check
- How do absolute and relative hypovolemia differ at bedside?
- Why is urine output trend a core shock-severity indicator?
- Which cues during rapid volume resuscitation require immediate respiratory escalation?