Oxygenation & Perfusion: Hypovolemic Shock

Pathophysiology/Causes

Risk Factors

Labs/Diagnostics

Complications

Collaborative Treatment

Symptoms

Tachycardia

Thirst

Rapid shallow respirations

Etiology: Loss of fluid volume externally (trauma, surgery) or internally (hemorrhage, burns)

Fluid replacement therapy

Large amounts of crystalloid solutions (LR, NS)

Blood products

Albumin

Treat underlying causes

Stop bleeding, rehydration, medications for N/V/D

Position in modified Trendelenburg (passive leg raising) to promote venous blood return

Oxygen therapy to maintain O2 concentration in remaining volume

External or internal fluid loss causes decreased intravascular volume

Venous return to heart is impaired. Decreases ventricular filling, stroke volume, and cardiac output. Arterial pressure decreases in response to lower CO and hypotension occurs.

Baroreceptors on aorta detect decreased pressure, activates sympathetic nervous system to compensate. Release of catecholamines, vasopressin, and RAAS activation.

Decreased systemic fluid volume and sympathetic diversion of blood from nonessential organs causes hypoperfusion of tissues. Hypoxic cells switch to anaerobic metabolism in absence of oxygen. Release of lactic acid causes metabolic acidosis as blood pH decreases.

Peripheral vasoconstriction to increase venous tone, increases BP to maintain vascular resistance against remaining fluid volume. Capillary damage and vascular leakage causes tissue edema and circulatory stasis.

HR and contractility increase to help heart meet workload demands. Impaired ventricular filling worsens SV and CO, further exacerbating cardiac workload until failure occurs.

Impaired tissue perfusion & hypoxia

Cyanosis

Anxious --> Confusion

Hypotension

Cells death occurs due to lack of oxygen and impaired metabolism, releases toxic components into circulation. Organs are dysfunctional as a result of cell death. Loss of compensatory measures leads to hemodynamic instability, progresses to multiorgan failure and death.

Infants and elderly are sensitive to fluid volume depletion and may refuse fluids

Decreased urine output

Kidney disease causing impaired reabsorption of salt and water, loss of fluid through urine

Cool extremities, delayed cap refill

Patients with trauma, injury, burns or postsurgical

ABGs consistent with metabolic acidosis (can be alkalotic too)

Lactate levels from lactic acid release by cells

Electrolytes showing sodium and potassium imbalances (high or low)

Cross-match blood in preparation for transfusion

Increased BUN, creatinine due to kidney failure

Prothrombin time to assess coagulopathy

CBCs alterations -- low hematocrit and hemoglobin due to hemorrhage, or hemoconcentration of blood components from fluid loss causes high values

Renal failure

Acute respiratory distress syndrome (ARDS)

Multiple organ dysfunction syndrome