Learning Objectives
By the end of this section, you will be able to:
- Discuss the pathophysiology, risk factors, and clinical manifestations of hypovolemic shock
- Describe the diagnostics and laboratory values for hypovolemic shock
- Apply nursing concepts and plan associated nursing care for patients with hypovolemic shock
- Evaluate the efficacy of nursing care for patients with hypovolemic shock
- Describe the medical therapies that apply to the care of patients with hypovolemic shock
The potentially life-threatening condition of hypovolemic shock results from a critical loss of volume in the intravascular space, which increases metabolic demand on the body. If the cause of volume loss is identified and appropriate treatment is initiated early, there is a chance of complete recovery (Taghavi, 2023). This module will review the specific pathophysiological causes of hypovolemic shock.
Pathophysiology of Hypovolemic Shock
There are two types of hypovolemic shock: absolute hypovolemia and relative hypovolemia. Commonly referred to as massive real fluid loss from the body, absolute hypovolemia is loss of blood that is visible. It is associated with:
- external hemorrhage
- internal hemorrhage
- gastrointestinal fluid loss from uncontrolled vomiting or diarrhea
- drainage from a fistula, an abnormal or surgically created passage between a hollow or tubular organ and the body surface
- hormonal abnormality not related to diabetes mellitus, such as diabetes insipidus, a pathologic process in which the body produces ineffective antidiuretic hormone, causing massive urinary output
- hyperglycemic induced diuresis
- diuresis
Commonly referred to as internal bleeding or third spacing of fluids rather than true loss of body fluids, relative hypovolemia is a volume adjustment within the body from the vascular space to the interstitial space, often called the third space. These episodes may be slow and incidental, but they can progress to hemorrhage depending on the mechanism of bleeding. Relative hypovolemia is associated with:
- bowel obstruction
- burn injury
- ascites, a condition in which fluid collects in the abdomen (Figure 23.6)
- long bone fracture
- ruptured spleen
- hemothorax, the accumulation of blood within the pleural space
- severe pancreatitis
- sepsis
In hypovolemic shock, lack of sufficient vascular volume causes decreased cell perfusion and hypoxia. To compensate, the sympathetic nervous system is activated to provide more blood flow to cells. Heart rate and contractility increase, as does the systemic tone of blood vessels. Blood pressure is normal to slightly elevated in the early phase of hypovolemic shock. When the body can no longer compensate, however, the patient develops hypotension and tachycardia with decrease of urinary output. The kidneys respond to decreased perfusion by retaining fluid to increase vascular volume.
The body is unable to maintain homeostasis in hypovolemic shock. In this state, the selective permeability of the cell membrane—key to maintaining optimal conditions for enzyme action and cell function, including aerobic metabolism—is lost due to hypoperfusion. Cellular metabolism converts to anaerobic metabolism because sufficient oxygen is not available at the cellular level. As a result, there is a buildup of lactic acid. In homeostasis, the liver is able to maintain normal lactic acid levels of less than 2 mmol/L. A combination of anaerobic metabolism causing increased lactic acid and a hypoperfused liver unable to clear the substance from the body can lead to lactic acidosis.
Continued hypoperfusion of cells leads to the movement of blood to vital organs of the body, particularly the brain and heart. Other organ systems experience even greater hypoperfusion because of this. As the hypovolemic shock state progresses, acidosis does not respond to treatment, cardiac output is further decreased, cell perfusion further deteriorates, and a hypoxic state exists throughout the body. Cells and tissues die, and multiple organ failure develops. Risk factors for hypovolemic shock include recent surgery, major blood loss, open wounds, draining fistulas, diuretic use, hyperglycemia, hyperthermia, and uncontrolled vomiting or diarrhea.
Clinical Manifestations
Clinical manifestations of hypovolemic shock depend on the severity of the hypovolemia. One of the earliest manifestations is a change in mental status, most commonly anxiety caused by decreased perfusion to brain cells. Other classic manifestations of hypovolemic shock include increased heart rate, decreased blood pressure, increased respiratory rate, decreased urinary output, and cool clammy skin.
Patients experience tachycardia as their heart attempts to compensate and provide more blood flow to cells. Hypotension is the result of low vascular volume. Respiratory rate and depth increase to provide more oxygen to cells and rid the body of carbon dioxide as the cellular metabolism switches from aerobic to anaerobic. The kidneys respond to low vascular volume by retaining fluid, causing urine output to drop. The skin is cool due to the diversion of blood to the vital organs.
Assessments and Diagnostics
Symptoms of hypovolemic shock vary in severity based on the fluid volume lost. While some symptoms are sudden, others are progressive and can lead to cell death and organ destruction. Early identification and prompt treatment of hypovolemic shock can be accomplished through thorough, timely, and accurate nursing assessments.
An initial patient assessment of mental status followed by vital signs will provide the nurse with direction as to whether a more focused assessment of body systems is needed. Patients with hypovolemic shock are often confused or agitated because of the lack of blood flow to the brain. Vital signs often include decreased blood pressure, tachycardia, and tachypnea when compared with their baseline status. Orthostatic hypotension may also be present. This condition is characterized by a drop of at least 20 mmHg in systolic blood pressure and 10 mmHg in diastolic pressure within three minutes of standing up from a sitting or lying position. Patient safety is a priority when assessing orthostatic hypotension. The nurse should assist the patient in position changes, encourage the patient to gently rise to a standing position from a supine or sitting position, and encourage the patient to dangle on the side of the bed before standing.
Physical assessment may reveal classic manifestations of dehydration, including dry mucous membranes and a decrease in skin turgor. The patient may also complain of thirst and headaches. Peripheral pulses may be weak or absent and capillary refill time may be extended due to low vascular volume. It is also important to assess urine output because it is a good indicator of perfusion to the kidney. A rate of 30 mL of urine per hour is reflective of adequate kidney perfusion. The nurse should closely monitor output trending down. Lower urinary output values should be communicated to the health-care team, as adjustments to the plan of care may be necessary.
Table 23.4 reviews manifestations of early and advanced hypovolemic shock.
| Type of Symptom | Early Hypovolemic Shock | Advanced Hypovolemic Shock |
|---|---|---|
| Blood pressure | Slightly low to normal or slightly elevated | Low blood pressure |
| Heart rate | Normal to slightly high | High heart rate |
| Respiratory rate | Normal to slightly high | High respiratory rate |
| Urine output | Normal to slightly low | Low (less than or equal to 30 mL/hour) |
| ABG | Normal with possible lower oxygen level | Evidence of hypoxia and metabolic acidosis |
| Capillary refill time | Normal to slightly long | Prolonged capillary refill time |
Diagnostics and Laboratory Values
There is not one specific diagnostic or laboratory test to determine the presence of hypovolemic shock; however, low blood pressure is the best indicator, followed by low urinary output. A panel of blood work is drawn to serve as a baseline from which to plan appropriate care and evaluate the effectiveness of treatment. Additional diagnostic testing may include radiologic imaging, endoscopy, or exploratory surgery to identify and stop the source of volume loss.
Analysis of the complete blood count (CBC) in hemorrhagic shock may indicate low red blood cell (RBC) counts with a drop in hematocrit and hemoglobin. These values may also be low due to the dilutional effect of high-volume fluid resuscitation used to treat hypovolemic shock.
Impaired perfusion to the kidney results in an increase in the markers of renal function such as blood urea nitrogen (BUN) and creatinine (Cr). Creatinine is considered the more accurate indicator of kidney function, as BUN may be affected by muscle damage from trauma or surgery.
Activation of the sympathetic nervous system causes an increase in serum glucose. Poor perfusion to the liver may cause an increase in liver markers SGPT (serum glutamic-pyruvic transaminase) and SGOT (serum glutamic-oxaloacetic transaminase), also known as ALT (alanine transaminase) and ALP (alkaline phosphatase). Fluctuation of sodium levels occurs as the body is rehydrated. Potassium levels may increase as the nutrient is released from damaged cells. Lab findings may include lactic acidosis or metabolic acidosis due to the accumulation of waste products.
Table 23.5 reviews key findings of hypovolemic shock.
| Test | Findings in Hypovolemic Shock | Rationale |
|---|---|---|
| Red blood cells (RBC) | High RBC hemoconcentration Low RBC hemodilution |
Hemoconcentration due to loss of plasma Hemodilution due to fluid resuscitation |
| Hematocrit (Hct) | High hemoconcentration dehydration Low volume overload hemodilution |
Hemoconcentration due to loss of plasma Hemodilution due to fluid resuscitation |
| Hemoglobin (Hgb) | High hemoconcentration dehydration Low volume overload hemodilution |
Hemoconcentration due to loss of plasma Hemodilution due to fluid resuscitation |
| Blood urea nitrogen (BUN) | High | Hypoperfusion to kidney |
| Creatinine (Cr) | High | Hypoperfusion to kidney |
| Liver markers | High | Damage to liver cells from hypoperfusion |
| Serum glucose | High | Stress response |
| Urine specific gravity | High urine specific gravity Low urine specific gravity |
Dehydration from loss of fluids Fluid resuscitation |
| Sodium (Na) fluctuation | High Low |
Fluctuations based on fluid status |
| Potassium (K) | High | As cell damage occurs, potassium migrates from inside to outside of the cell |
| Lactate | High | Anaerobic metabolism |
| Acid base status | High acidic | Accumulation of metabolic waste products |
Nursing Care of the Patient with Hypovolemic Shock
Nursing care for patients with hypovolemic shock focuses on identifying the source of vascular fluid loss, stopping the fluid loss, restoring volume, and supporting all body systems as needed. If an overt hemorrhage is present, priorities of care include stopping the bleeding, which may be achieved by applying direct pressure or cold applications or elevating the site, as appropriate. In severe cases, patients may require cold saline flushed into indwelling tubes—for example, patients with presumed gastrointestinal bleeding may need a nasogastric tube. The patient may also require surgery to stop the loss of volume. Preoperative nursing interventions include providing information and emotional support for the patient and their family, ensuring that all preoperative data have been accumulated, and maintaining the patient’s baseline hemodynamic status. The nurse may also need to adjust medications, schedule diagnostic tests, and complete a clinical handover and transfer of professional responsibility and accountability.
Other top nursing priorities include inserting and maintaining intravenous access devices to supply potential blood and blood products or other fluids. The type and extent of volume loss dictate the quantity and type of volume required. For example, if a patient is bleeding due to toxic effects of blood thinners, patients may require platelets or fresh frozen plasma for volume support. Some patients require the use of hemodynamic monitoring to evaluate the effectiveness of therapy.
Restoration of vascular volume is achieved by administering intravenous fluid—such as 0.9 percent normal saline or other isotonic solutions—at a rapid and high rate. This process is commonly referred to as volume resuscitation. These patients require frequent nursing assessments because they may not be able to tolerate rapidly administered, high-volume fluids. For example, a patient may have an underlying cardiac or renal disease that could worsen in response to fluid resuscitation. Volume resuscitation can increase the likelihood of these patients not being able to tolerate the increase of fluids, resulting in pulmonary edema. The nurse should make the provider aware of any change of respiratory status, including breath sounds to prevent the development or worsening of pulmonary edema. Hemodynamic monitoring is often needed to manage fluid resuscitation efforts.
The type and amount of solution used for volume resuscitation generally depend on the patient’s fluid and electrolyte status, acid-base status, and organ function (Urden et al., 2022). Crystalloids and colloids are often used for volume replacement (Table 23.6). Crystalloids contain nonprotein substances, such as minerals, salts, and sugars, while colloids contain large molecules of proteins or starches, which help restore osmotic pressure and fluid volume. Blood products are used when shock is caused by blood loss (Urden et al., 2022).
| Intravenous Fluid |
Crystalloids | Colloids |
|---|---|---|
| Contents | Nonproteins, minerals, salts, sugars | Large molecules or proteins or starches |
| Use | Maintenance of adequate fluid and electrolyte balance | Used as plasma substitutes for short-term replacement of fluid volume while the cause of the problem is being addressed |
| Example | Normal saline (0.9%) is a replacement solution used to increase plasma volume; it can be infused with any blood product. Ringer’s lactate is a balanced salt solution containing sodium, chloride, calcium, potassium, and lactate. |
Human-made (starches, dextran, or gelatins) or naturally occurring (albumin or fresh frozen plasma [FFP]) Bigger molecules stay in the blood longer before passing to other parts of the body. |
Link to Learning
Refer to this website for a review of crystalloids and colloids to help nurses understand fluids and their use.
Patients experiencing hemorrhagic shock may require the administration of multiple units of blood. Nursing care should focus on safety practices for blood administration and assessment for potential complications, as the administration of multiple units of blood may cause the patient to experience several potentially dangerous conditions:
- The administration of cold or room-temperature blood can cause the core body temperature to drop, resulting in hypothermia. Blood-warming baths, warm saline, or radiant and microwave warmers are used at some institutions to warm blood and prevent hypothermia.
- Patients receiving blood transfusions are also at risk for dilutional coagulopathy if they do not receive sufficient clotting factors in the blood products they receive. It is important for the nurse to monitor the patient for bleeding and follow all appropriate precautions. It may be necessary to administer platelets or fresh frozen plasma.
- Citrate toxicity is another potential complication of blood transfusions. Citrate is used to keep banked blood from clotting. (Banked blood refers to units of blood products donated and available for a recipient in need.) It prevents the initiation of clotting cascade by binding to calcium. When the citrate in the transfused blood binds to calcium in the patient’s system, citrate toxicity results. The result is hypocalcemia and hypomagnesemia. Manifestations include hypotension, arrhythmias, nervous system excitability, laryngospasm, and tetany.
- Finally, hemolysis is the destruction of red blood cells. It results from interactions of antibodies on the recipient’s plasma with antigens on the donor’s red blood cells. Manifestations include fever, flank pain, and red or brown urine.
Table 23.7 reviews nursing care practices for patients experiencing hypovolemic shock.
| Steps for Nursing Care | Nursing Care Practices | Rationale |
|---|---|---|
| Assessment for hypovolemia | Trending of vital signs Dehydration assessment Hourly urine output Assessment orthostatic hypotension |
Prevention of hypovolemic shock is the best treatment. |
| Identify source | Absolute hypovolemia Relative hypovolemia |
Identifying and stopping the source of fluid loss can prevent the progression of hypovolemic shock. |
| Stop source | Prepare for surgery Prepare for procedures to correct intravascular volume loss |
Identifying and stopping the source of fluid loss can prevent the progression of hypovolemic shock. |
| Intravenous access | Secure and maintain vascular access | Volume resuscitation and administration of blood and blood products can prevent the progression of hypovolemic shock. |
| Volume resuscitation | Frequent, accurate assessments to evaluate the patient’s response to rapid high-volume, high-rate volume replacement | Complications of volume resuscitation may be prevented. |
| Blood transfusion and blood product administration | Follow all policies and procedures for blood and blood product infusion | Prevention of complications is key to patient recovery. |
| Hemodynamics | Accurate management of hemodynamic monitoring systems and accurate reporting of findings guide and evaluate the patient’s response to care | Prevention of complications and evaluation of treatments are keys to decreasing morbidity and mortality. |
Recognizing Cues and Analyzing Cues
The nurse can recognize cues of hypovolemic shock through assessment and trending of vital signs. When determining the state of a patient’s homeostasis, a series of vital signs is more representative than any one set. By recording accurate and frequent vital signs, the nurse may recognize a concerning trend. The nurse should report such a trend to the provider to prevent the full development of hypovolemic shock.
Vital signs associated with the development of hypovolemic shock include marked tachycardia over 100 beats per minute, decreased systolic blood pressure, narrowed pulse pressure, immeasurable diastolic pressure, marked decrease or no urinary output, depressed mental status, cold pale skin, cool clammy skin, delayed capillary refill time, anxiety, pallor, and increased respiratory rate. Furthermore, a change in mental status is often present. These changes—along with a history or evidence of volume loss, either absolute or relative—should cue the nurse to the potential diagnosis of hypovolemic shock.
In the early phases of hypovolemic shock, patients may complain of thirst or muscle cramps. As the condition progresses, so does the lack of perfusion to cells, causing hypoxia to cells with the conversion of aerobic to anaerobic metabolism and a buildup of waste products. All body systems may experience a decrease in perfusion during hypovolemia. The patient may experience chest pain, abdominal pain, ileus, change of mental status, dry mucous membranes, or decreased skin turgor.
Accurate and timely assessments are required to prevent long-term complications of hypovolemic shock—especially for patients experiencing excessive or prolonged diarrhea, severe burns, protracted or excessive vomiting, excessive sweating, bleeding from cuts or wounds, bleeding from traumatic accidents, internal bleeding from abdominal organs, or ectopic pregnancy. At-risk patients require frequent and accurate assessments for detection and initiation of treatment to be most effective.
Prioritizing Hypotheses, Generating Solutions, and Taking Action
Nursing care for hypovolemic shock requires a multisystem approach with input from a variety of health-care team members. The extent of volume loss can guide the level of care needed by the patient. All body systems must be supported, and any complications must be prevented. The patient and family need to be included in the development of the treatment plan, with appropriate education and emotional support provided by the nurse.
The goals of therapy include restoring intravascular circulating blood volume, preserving hemodynamic function, effecting the redistribution of circulating volume, addressing the underlying cause of fluid loss, and reversing the progression of inadequate tissue perfusion. These efforts are aimed at preventing organ damage. Priorities of care include the insertion of intravenous access devices, including central lines to restore circulating blood volume via volume resuscitation. Hemodynamic monitoring is often required to determine and evaluate the effectiveness of treatment. For the patient receiving volume resuscitation, frequent assessments should be completed in a timely and accurate manner. Any change in the patient’s baseline status in general, with particular attention to the respiratory status, needs to be communicated to the provider to prevent complications of high-rate, high-volume resuscitation.
Clinical Safety and Procedures (QSEN)
Volume Resuscitation for the Patient with Hypovolemic Shock
The delivery of volume replacement for the patient with hypovolemic shock will depend on the trigger of volume loss. If volume loss is from increased elimination from diarrhea, sweat, vomiting, or high amounts of urine, the nurse will anticipate hanging crystalloid solution of 0.9 percent isotonic normal saline or lactated Ringer’s solution. Hemodynamic monitoring with serial pulses, oxygen saturation, and blood pressures will gauge the patient’s response to treatment. If the patient’s fluid losses are from bleeding, other products such as packed red blood cells or plasma products may be considered.
Some patients may require surgery to preserve hemodynamic function. The nurse should complete all preoperative nursing interventions, including maintaining nothing-by-mouth status (NPO), ensuring completion of informed consent, determining blood type, and performing a type and cross match, as well as providing patient and family education and emotional support.
The nurse may assist with improving blood pressure by positioning the patient to increase venous return to the heart, thereby supplementing cardiac output. The preferred patient position is lying flat with the legs elevated about 12 inches. Unlike the Trendelenburg position, this position will not impair the patient’s breathing ability. Some institutions recommend passive leg raises to improve the flow of blood back to the heart.
All organ systems should be supported to prevent damage. Mean arterial pressure (MAP) is often used to determine the effectiveness of organ perfusion; an acceptable minimum value is 65 mmHg or above for patients who have an arterial line. MAP levels must maintain a minimum of 65 mmHg for cells to receive the oxygen and nutrients needed to metabolize energy in amounts sufficient to sustain life Additionally, the patient should be kept warm, as a cold patient has a greater chance of developing acidosis.
Evaluation of Nursing Care for the Patient with Hypovolemic Shock
After treatment is initiated, it is important for the nurse to evaluate the patient’s response to therapy and make appropriate modifications. The goal of treatment is for the patient to return to their baseline status.
An assessment of hemodynamics will be necessary to determine whether the patient has adequate cardiac output. If invasive hemodynamic measurement of cardiac output is not available, the following signs also indicate adequate cardiac output and normovolemia: a urine output of at least 30 mL/hour, the presence of peripheral pulses, systolic blood pressure of 20 mmHg from baseline, a heart rate between 60 to 100 beats per minute, and a normal level of consciousness. Furthermore, decreased anxiety level is an important indicator of perfusion to the brain.
Medical Therapies and Related Care
The health-care team must work together in an organized manner to respond to the emergency of hypovolemic shock. The goals of treatment include identifying the source of volume loss, stopping the source of volume loss, and restoring appropriate volume. Standard treatment for volume replacement includes the insertion of large, 14- to 16-gauge intravenous catheters or the insertion of a central line for fluid administration. Fluids, blood, and blood products are administered based on the individual needs of the patient.
Identification and correction of the cause of intravascular volume loss is the first step in reversing hypovolemic shock. Some patients require the administration of medications to maintain hemodynamic stability. Medications that increase blood pressure are used to support patients in hypovolemic shock; these include epinephrine, norepinephrine, dopamine, and dobutamine. Epinephrine is the strongest vasoconstrictor of all vasopressors as it increases blood pressure, heart rate, and cardiac output. Norepinephrine increases arterial blood pressure through vasoconstriction and has little effect on heart rate. Dopamine and dobutamine are inotropes used to increase cardiac contractility.