Comprehensive Review of Shock: Causes, Effects and Treatments

1. Describe the pathophysiology of Shock.

2. Identify the primary forms of shock.

Hypovolemic shock is a loss of circulating fluid volume (Urden, Stacy, Lough, 2014). Cardiogenic shock occurs when the heart is unable to effectively pump blood forward (Urden, Stacy, Lough, 2014). Anaphylactic shock is a result of a hypersensitivity reaction (Urden, Stacy, Lough, 2014). Neurogenic shock is caused by anything that interrupts the sympathetic nervous system (Urden, Stacy, Lough, 2014).  Septic shock occurs when microorganisms invade the body and initiate a systematic inflammatory response causing maldistribution of blood flow to the tissues (Urden, Stacy, Lough, 2014).

3. For each type of shock identify the causative factors and impact to the patient

As hypovolemic shock is a loss of circulating fluid volume, there is a number of different ways this can occur. Factors such as loss of whole blood from surgery or trauma, loss of plasma by thermal injuries or large lesions, and loss of other body fluids for instance from vomiting or diarrhea are considered absolute factors (Urden, Stacy, Lough, 2014). Relative factors include conditions that promote vasodilation, increased capillary membrane, and decreased colloidal osmotic pressure (Urden, Stacy, Lough, 2014).

Dysfunction of the hearts muscle, mechanical or rhythmic system which impairs the ability of the heart to pump blood forward can result in cardiogenic shock. Muscular injury such as ischemic injury, myocardial infarction, cardiomyopathy or acute myocarditis can have an impact on the hearts ability to pump blood forward (Urden, Stacy, Lough, 2014). Septal wall rupture, ventricular aneurysm, pulmonary embolus, cardiac tamponade and constrictive pericarditis can damage the mechanical system of the heart and result in cardiogenic shock (Urden, Stacy, Lough, 2014). Both bradydysrhythmias and tachydysrhythmias also can impact the hearts ability to pump blood forward resulting in cardiogenic shock (Urden, Stacy, Lough, 2014).

Anaphylactic shock is caused by a immunologic antibody-antigen response or nonimmunologic activation of mast cells and basophils. (Urden, Stacy, Lough, 2014). There are many triggers that can cause an individual to have an anaphylactic allergic reaction. Food, biologic agents, environmental agents, drugs and venom can all trigger an anaphylactic reaction (Urden, Stacy, Lough, 2014).

Neurogenic occurs as a result of a blockage of sympathetic outflow from the vasomotor center of the brain (Urden, Stacy, Lough, 2014). The most common cause of neurogenic shock is related to a spinal cord injury (Urden, Stacy, Lough, 2014).

Sepsis is caused by gram negative and gram positive aerobes, anaerobes, fungi and viruses (Urden, Stacy, Lough, 2014). Sepsis and septic shock is associated with both intrinsic factors and extrinsic factors. Intrinsic factors include advanced age, malignances, burns, AIDs, diabetes, substances use, and malnutrition (Urden, Stacy, Lough, 2014). Extrinsic factors include invasive devices, medication therapy, fluid therapy, wounds, immunosuppressive therapy (Urden, Stacy, Lough, 2014). These factors contribute to the development of sepsis and septic shock.

4. For each type of shock identify clinical presentations and why they occur

Cardiogenic shock results in decreased stroke volume and decreased cardiac output (Urden, Stacy, Lough, 2014). Thus, patients manifest and compensate with decreased blood pressure and tachycardia (Urden, Stacy, Lough, 2014). As blood is not moving forward properly, blood begins to back up into the pulmonary system resulting in pulmonary edema (Urden, Stacy, Lough, 2014).  As such, this would manifest as tachypnea, crackles in the lungs, and increased pulmonary artery occlusion pressure (Urden, Stacy, Lough, 2014).

During anaphylactic shock, biochemical mediators causes vasodilation and constriction of smooth muscle (Urden, Stacy, Lough, 2014). With vasodilation, circulating blood volume increases causes hypotension, tachycardia, pruritis, erythema, and angioedema (Urden, Stacy, Lough, 2014). As constriction of smooth muscle occurs, patients may experience a sensation of a lump in their throat, cough, dyspnea, dysphagia, hoarseness, stridor, wheezing and rales (Urden, Stacy, Lough, 2014).

Neurogenic shock is caused by loss of sympathetic tone which results in massive vasodilation resulting in a decreased cardiac output and stroke volume (Urden, Stacy, Lough, 2014). This manifests as hypotension and decreased heart rate (Urden, Stacy, Lough, 2014). Additionally loss of sympathetic tone leads to impaired thermoregulation and therefore manifests as hypothermia (Urden, Stacy, Lough, 2014). Due to the lack of perfusion,  organs such as the kidneys and brain are effected result in decreased urine output and changes in mental status (Urden, Stacy, Lough, 2014).

Invading microorganisms causes a systematic inflammatory response which results in activation of biochemical, humoral and cellular mediators causing peripheral vasodilation (Urden, Stacy, Lough, 2014). Increased cardiac output, decreased systemic vascular resistance, wide pulse pressure, bounding pulse, pink warm flushed skin, decreased right atrial pressure, and decreased blood pressure occur as a result (Urden, Stacy, Lough, 2014). Due to the maldistribution of blood volume, patients exhibit increased heart rate, decreased urinary output, and decreased PaO2 and PaCo2. This is related to decreased perfusion in organs such as the kidneys and lungs. Ultimately, as tissue perfusion continues to decrease the respiratory system becomes further affected and cellular metabolism becomes impaired

5. Describe the medical treatment options for each type of shock and how each treatment modality works to improve the impact to the patient and support them in their recovery.

The medical treatment for cardiogenic shock involves treating the underlying problem and improving the heart’s pumping ability. One of the main problems in cardiogenic shock is decreased cardiac output. Inotropic agents and vasopressors are used to increase contractility, and ensure adequate blood pressure and perfusion (Urden, Stacy, Lough, 2014). In a study conducted by Leurent, Auffret, Pichard, Laine, and Bonello (2019) it was found that intra-aortic balloon pump therapy assists in management of cardiogenic shock by reducing cardiac afterload and myocardial oxygen consumption and improving coronary blood flow. In terms of treating the underlying problem, revascularization via percutaneous coronary intervention or coronary artery bypass, and fibrinolytic therapy may significantly assist in correcting the cardiac problem (Urden, Stacy, Lough, 2014).

Immediate treatment of anaphylactic shock is necessary to preventing death. The first-line treatment is epinephrine 0.2-0.5mg every 5-10 minutes until anaphylaxis resolves (Urden, Stacy, Lough, 2014). Fluid replacement is also necessary for patients experiencing low blood pressure. Crystalloid or colloid solutions and vasopressor may be used to restore perfusion (Urden, Stacy, Lough, 2014). Additionally, medications used to inhibit the histamine response such as diphenhydramine may be used (Urden, Stacy, Lough, 2014). Education regarding prevention will be necessary to ensure another reaction does not occur.

Treatment of neurogenic shock can be a complicated approach. The goals of treatment are to prevent hypovolemia, bradycardia, and hypothermia (Urden, Stacy, Lough, 2014). Treatment may include fluid replacement to correct hypovolemia, vasopressors may be used to increase blood pressure and hypothermia treated by means of regulating the environment (Urden, Stacy, Lough, 2014).

As with many other types of shock, the goals of septic shock are reversing the hypoperfused state. Fluid resuscitation along with vasopressor and inotropic agents are used to reduce hypovolemia and increase cardiac output and blood pressure (Urden, Stacy, Lough, 2014). Low dose corticosteroids have been found to assist with severe septic shock in patients who remain hemodynamically unstable despite fluid resuscitation and vasopressor therapy (Lemieux and Levine,  2019). The findings of the study suggest that in patients with increasing doses of vasopressors and evidence of multiorgan dysfunction corticosteroids may decrease mortality (Lemieux and Levine, 2019).

6. For each type of shock explore the nursing considerations for assessing, managing the clinical needs.  Also, how the nurse and interprofessional team provides emotional and or education support to the patient/family.

Prevention of cardiogenic shock is primarily important. This includes mitigating the risk of developing cardiac related disorders. The Heart and Stoke Foundation Canada (2019) states that unhealthy diet, physical inactivity, unhealthy weight, smoke stress, and alcohol use all contribute to heart disease. Educating patients of the risks and providing information for patients that have heart disease is an essential nursing intervention.

Nursing interventions relating to anaphylactic shock include administering medications, facilitating ventilation,  and administering volume replacement (Urden, Stacy, Lough, 2014). As constriction of smooth muscles occurs with this type of shock, airway management is imperative. Nurses should assist patients with deep, slow respirations and position the patient for optimal airway clearance (Urden, Stacy, Lough, 2014).

As neurogenic shock is often caused by spinal cord injuries, having an awareness of how to provide immobilization of the spinal cord as a nurse is important (Urden, Stacy, Lough, 2014). Further, due to the immobilization, patients will not mobilize as much and are at risk for DVT. Patients should be educated on DVT and ways to prevent such as passive range of motion exercise, application of sequential pneumatic stockings, and administration of anticoagulation therapy (Urden, Stacy, Lough, 2014).

Septic shock is caused by microorganisms. Therefore, as a nurse handwashing, aseptic technique and reducing the incidences of infection is important for preventing sepsis and septic shock (Urden, Stacy, Lough, 2014). In a study conducted by Robert et al. (2017) it was found that delaying antibiotic therapy after sepsis recognition increases mortality. Therefore, as nurses, it is critical that management of a patient with sepsis occurs quickly.