Shock: Cardiogenic, Hypovolemic, and Septic
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Article at a Glance
- Three common types of shock are hypovolemic shock, cardiogenic shock, and septic shock.
- During shock, the body attempts to regain cardiac output through compensatory mechanisms.
- Read on to learn about nursing care and assessments for shock.
This article covers the three common types of shock, the pathophysiology of shock, and compensatory mechanisms. The three most prevalent types of shock are:Common Types of Shock
Hypovolemic shock stems from low circulating fluid volume. Most often, shock is caused by a gastrointestinal (GI) bleed or trauma. Another cause of hypovolemic shock is an endocrine disorder called diabetes insipidus, where the patient puts out large volumes of urine. Patients with hypovolemia have a low blood volume circulating in the body.Hypovolemic Shock
Cardiogenic shock results from decreased myocardial contractility, or the decreased ability of the heart to pump. The most common etiology for cardiogenic shock is a massive left ventricular myocardial infarction. The myocardial infarction limits the muscle of the heart pumping ability.Cardiogenic Shock
Septic shock is one of the deadliest phenomena in patient care today. The etiology for septic shock is sepsis from any type of infection. Examples of infections that could lead to shock include pneumonia, an infected wound, or a urinary tract infection. A localized infection can also progress to sepsis, and then the sepsis can progress to septic shock. Another cause for septic shock is decreased vascular resistance, or massive vasodilation. The massive vasodilation is due to a system-wide inflammation from sepsis. In sepsis, patients lose fluids due to massive vasodilation.Septic Shock
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The etiology for each type of shock differs, but the pathophysiology follows a similar path. Each type of shock results in a decrease in cardiac output. A decrease in cardiac output leads to decreased tissue and organ perfusion, eventually leading to cellular hypoxia and cell death. Read: Which Oxygen Delivery Device Should I Choose?Pathophysiology
The following compensatory mechanisms may be observed in patients experiencing shock: The catecholamines epinephrine and norepinephrine are released by the sympathetic nervous system, resulting in an increased heart rate. Epinephrine and norepinephrine also cause vasoconstriction to increase cardiac output and increase tissue perfusion. Adrenocorticotropic hormone (ACTH) is released from the anterior pituitary. ACTH signals the adrenal cortex to release aldosterone and cortisol. These hormones are considered flight or fight hormones. Cortisol increases blood glucose and fights inflammation, while aldosterone causes sodium and fluid retention. Antidiuretic hormone (ADH) is another hormone released by the posterior pituitary. ADH tells the kidneys to retain water to increase fluid volume and tissue perfusion. Overall, the endocrine system’s response aims to improve tissue perfusion and cardiac output. Due to cellular hypoxia, the chemoreceptors in the aortic arch are stimulated. Patients in shock will often have an increased respiratory rate.Compensatory Mechanisms in Shock
Nervous System Response
Endocrine System Response
Chemoreceptor Response in the Aortic Arch
As a result of the compensatory mechanisms, patients in shock will present with early signs and symptoms. The nurse has an important role in monitoring for early signs and symptoms of shock. Early signs and symptoms of shock are: The nurse should be aware of and report these early signs and symptoms. Early recognition and report of shock can help the patient receive treatment before it progresses.Nursing Care: Early Signs and Symptoms
Nursing assessments focus on both the early and active signs and symptoms of shock. Assessments that are important for all types of shock include: One of the early signs of hypoxemia is mental status change and restlessness. Assessing inputs and outputs is essential for treating hypovolemic shock. It is also important for cardiogenic and septic shock because of the potential for decreased kidney perfusion. It is important to monitor if the patient is retaining volume that is administered to replace the volume losses. Heart rate and blood pressure should be monitored for hypovolemia. Oxygen saturation should also be monitored to assess for compensation for hypovolemia. Arterial blood gases are checked because of the potential for anaerobic metabolism and lactic acid production. The increased cortisol in the body increases the patient’s blood glucose. It is important to assess for signs and symptoms of bleeding that may contribute to hypovolemia. For example, stool should be monitored to check for a GI bleed, dressings are monitored on wounds, and abdominal girth is checked for those at risk of internal bleeding. The capillary refill time and pulse quality are tangible indicators of a patient’s fluid status. CVP is a hemodynamic measurement that is important with every type of shock. CVP can be obtained through the distal port of a triple lumen of a central line and provides a direct reflection of the pressure in the right side of the heart, also known as the preload. If the blood pressure drops too low, the body can go into shock. Monitoring is crucial.Nursing Assessments
Neurology Checks
Inputs and Outputs
Daily Weights
Vital Signs
The respiratory rate is often overlooked. Changes in the respiratory rate are red flags that the shock is progressing.Blood Glucose
Signs and Symptoms of Bleeding
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Capillary Refill Time and Pulse Quality
Central venous pressure (CVP)
CVP measurements, which range from about 8–12 mm Hg for patients in shock, guide fluid replacement. CVP monitoring is one of the hemodynamic staples used to monitor patients in shock.
The treatment for shock varies depending on the type of shock. Treatments for Shock
The treatment of hypovolemic shock is to replace volume loss. If the patient is bleeding, they should receive a blood transfusion. If the patient lost fluids, they should receive fluids. The rule of thumb for fluid replacement is 300 mL of isotonic solution for every 100 mL of fluid lost.Hypovolemic Shock
The main cause of cardiogenic shock is a massive left ventricular myocardial infarction (MI). Treatment involves fixing the MI, which may require the patient to be sent to the catheterization lab to remove a blockage in the arteries. Until the MI is fixed, the patient may be administered oxygen, aspirin to prevent platelet aggregation, and anticoagulation drips. The patient will need a 12-lead electrocardiogram (ECG) as soon as possible. A patient who experienced a massive MI that resulted in cardiogenic shock will likely receive an intra-aortic balloon pump. This device is inserted directly into the patient’s aorta to control blood flow, helping to decrease afterload. During diastole, the balloon inflates the aorta to perfuse the coronary arteries and retain blood in the heart, and during systole, it helps pull blood into the systemic circulation. The intra-aortic balloon pump helps to reduce the workload of the heart. A similar device to the balloon pump may be used, but these devices all serve the same purpose. Patients may also have a pulmonary artery catheter inserted to obtain CVP measurements, cardiac output, and cardiac index. Managing cardiogenic shock is complicated. Therefore, having hemodynamic measurements is valuable. The goal of cardiogenic shock treatment is to restore heart function and blood pressure. This goal is primarily achieved through procedures, such as a catheterization procedure to fix a blockage and an intra-aortic balloon pump. Medications and support devices also help. Positive inotropic drugs, such as dobutamine, can help increase the contractility of the heart. Diuretics can help pull volume off.Cardiogenic Shock
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The main treatment goal for septic shock is treating the underlying infection. If a patient has a bacterial infection, they should receive antibiotics. Blood cultures are used to identify the bacteria and determine an appropriate antibiotic regimen. While waiting for the results of the culture, the patient should be started on broad-spectrum antibiotics, which are deescalated once the bacteria is identified. Until the pathogen is identified and treated, the mainstay of treatment is fluids. Fluids are important because massive vasodilation occurs in septic shock due to inflammatory mediators, which also damage the capillaries and cause massive capillary leakage. Patients in septic shock are in significant danger for severe hypotension and end-organ damage. Septic shock has a 50% mortality rate. That is why it is so important to replace fluids and treat the underlying infection aggressively and swiftly. Every minute counts. Vancomycin is a broad-spectrum antibiotic. The three primary types of shock are hypovolemic, cardiogenic, and septic. While the pathophysiology of these forms of shock are similar, the etiology and treatments are type-specific. It is important that the signs and symptoms of shock are identified early to treat the shock and stop its progression.Treatment of Septic Shock
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