Hypovolemic shock: Clinical sciences

Hypovolemic shock is a life-threatening condition associated with decreased intravascular volume, which in turn leads to decreased venous return to the heart, decreased cardiac output, and eventually shock.

Now, hypovolemic shock can be defined as hemorrhagic or non-hemorrhagic. Hemorrhagic shock is associated with blood loss, which can be seen in traumatic conditions, such as a ruptured spleen; or non-traumatic conditions, like variceal bleeding.

On the other hand, non-hemorrhagic shock is associated with fluid loss, most commonly from dehydration, like after prolonged vomiting or diarrhea, as well as severe widespread burns.

Now, patients presenting with signs and symptoms of hypovolemic shock will generally present as unstable. Start by immediately performing an ABCDE assessment, then begin acute management. Stabilize their airway, breathing, and circulation. This means that you might need to intubate the patient. Next, obtain IV access with 2 large bore IVs and start IV fluids. Finally, put your patient on continuous vital sign monitoring, such as pulse oximetry, blood pressure, and heart rate.

Once you’ve stabilized the patient, obtain a focused history and physical examination. History often reveals the underlying cause or source of fluid or blood loss, as well as symptoms of organ hypoperfusion. For example, hypoperfusion of the brain can result in lethargy and confusion, while kidney hypoperfusion can lead to oliguria.

Additionally, individuals might report postural dizziness.

On the other hand, a physical exam primarily reveals signs of shock, such as hypotension, and tachycardia, as well as weak peripheral pulses and low jugular venous pressure. Additionally, patients can present with pale, clammy skin; decreased skin turgor; dry mucous membranes; and cold extremities.

If you suspect hypovolemic shock, the next step is to order labs, which can also help you determine the type of shock. These include CBC, lactate, and CMP, as well as PT, PTT, and INR.

Okay, now let’s look at how H&P findings plus lab values can help you determine the type of shock, starting with non-hemorrhagic shock. These individuals typically have a history of prolonged vomiting and diarrhea, or widespread burns. All these conditions can lead to fluid loss.

Additionally, CBC usually reveals a high hemoglobin level, since fluid loss can result in hemoconcentration.

Next, lactate will be elevated because hypoperfused organs are forced to switch to anaerobic metabolism, producing lactate as a byproduct.

On the other hand, CMP might reveal elevated BUN, creatinine, and transaminases due to renal and hepatic hypoperfusion.

Finally, PT, PTT, and INR are usually normal.

At this point, you’ve determined that your patient has non-hemorrhagic shock, so the next step is to assess each of your patient’s organ systems for the cause of fluid loss. In patients who describe excessive diarrhea or vomiting, think of gastrointestinal fluid losses due to inflammatory bowel disease or underlying gastrointestinal infection, like cholera or giardiasis.

On the other hand, if your patient presents with severe blistering or eschar formation, consider burn injury and fluid loss through the skin.

Next, a history of diuretic use or polyuria should make you suspect underlying renal fluid losses, such as diuretic-induced dehydration or salt-wasting nephropathy.

Finally, if there’s severe abdominal pain or ascites, consider intravascular volume depletion due to third-spacing, where fluid leaks out of the vascular circulation into the interstitial space between cells,

which is common in pancreatitis due to inflammation and in cirrhosis due to low albumin levels.