Classfication: Adrenergic agonist
Mechanism of action: acts on (alpha) receptors causing vasocontriction of blood vessels, and to a lesser degree beta receptors (inotropic effects) which increase cardiac output
Use: shock, hypotension, to increase perfusion to VS
Side/adverse effects: HA, tachycaardia, dysrhythmias, N/V/diarrhea, dyspnea
Nursing Implications: need continuous ECG monitoring, BP monitoring, I/O, monitor for fluid volume excess (CHF) should have CVP or PWP during injection
Classification: non-selective adrenergic agonist
Mechanism of action: beta agonist (B1 and B2) leading bronchodilation, cardiac, and CNS stimulation
Use: shock, cardiac arrest, anaphylaxis, allergic reactions, acute asthma attacks
Side/Adverse effects: tremor, anxiety, insomnia, cerebral hemorrhage, tachycardia, dysrhythmias, hypertension, anorexia, N/V, dyspnea
Continuous ECG monitoring during administration with CVP, PCWP if possible arterial BP monitoring recommended. Can give VIA ET tube
***Risk for Shock
What is shock?
A syndrome characterized by hypo-perfusion of body tissues that leads to diffuse tissue hypoxia, abnormal cellular metabolism and ultimately cell death
What are factors that contribute to normal regulation of blood flow?
- Adequate blood volume
- Ability of the heart to effectively pump
- Vascular tone
Shock develops when cells do not receive adequate blood flow/O2 thus altering metabolism
- Supply/demand problem
Shock cannot be defined as a specific disease, but manifests within many disease processes
What is the impact of shock on society?
- Increasing incidence
- Critical care environment
- Increased incidence of sepsis
- Brings high mortality rate
- Financial burden
What are risk factors for developing shock?
- Age extremes
- Poor general health
- Multiple medical/surgical therapies
- Long term medical instrumentation
What is the general pathophysiology of shock?
Shock is a syndrome that occurs when the body attempts to achieve homeostasis in response to perfusion/oxygen problem.
What are the causes of hypovolemic shock?
- Loss of other body fluids (vomiting, diarrhea, DI)
- Pooling of blood from ascites, peritonitis
- Internal bleeding from ruptured spleen
What is actual hypovolemia?
Loss of whole blood or plasma
What is relative hypovolemia?
Internal shift of fluids from intravascular space to extravascular space
What is hypovolemic shock?
Decreased circulating blood volume (size of the vascular compartment remains the same, while the blood volume decreases)
What is cardiogenic shock?
Defect in ability of heart to pump and move blood forward
What are the causes of cardiogenic shock?
- Previous acute MI
- Large MI
- LVEF 35% or less
Most commonly ventricular ischemia particularly related to acute MI. Other causes are dysrhythmias and structural defects which interfere with the heart's ability to effectively pump blood
What is distributive shock (neurogenic, anaphylactic, septic)?
Defect in vascular smooth muscle tone: size of the vascular compartment enlarges but blood volume remains the same (vasodilation). Same mechanism for neurogenic, anaphylactic and septic shock
What is neurogenic shock?
- Hemodynamic result of SCI at T5 or above
- Spinal anesthesia
- Vasomotor center depression
What is anaphylactic shock?
Massive vasodilation from histamine, leukotriene, mast cells. Massive systemic allergic reaction
What is septic shock?
Systemic infection. Endotoxin from microorganism causes vasodilation
How do all types of shock alter hemodynamics in the same way?
Decrease in mean arterial pressure (MAP)
Continued decresased perfusion
Increase in SV, Increase HR, Increase CO, Increase SVR, Increase MAP
Further continued decreased perfusion
What are the stages of shock?
Shock progresses through four stages. The progression from one to the next can be halted/stopped with treatment/intervention.
What happens in the initial stage of shock?
First stage. No signs or symptoms. Changes are cellular. Shock is reversible.
What happens in the compensatory stage of shock?
Second stage. Compensatory mechanisms kick in to return cells to pre-shock state
- Most metabolic need of body continues to be met because of the effects of the SNS/RAAS
- Decreased MAP activates SNS leading to selective peripheral vasoconstriction and blood shunts to brain and heart.
- SNS also causes increase in HR and contractility leading to increased CO increasing O2 to myocardium
- Decreased blood flow to kidneys activites RAAS causing vasoconstriction and increased BP. Also ADH released causing H20 reabsorption, increasing blood volume
- Fluid shift from intracellular to intravascular spaces due to decreased hydrostatic pressure and osmotic gradient also increased blood volume
All lead to increased preload, increased HR, contractility, CO, BP
What happens in the progressive (uncompensated) stage of shock?
- Compensatory mechanisms fail and irreversible cellular damage occurs
- Tissue hypoxia/cell death
- Metabolic acidosis
What are the signs and symptoms of progressive stage of shock?
- Diminished LOC
- Increased HR
- Increased myocardial contractility
- Possible dysrhythmias
- Decreasing BP and MAP
- Low PaO2
- Metabolic acidosis, low pH
- Aggressive management needed to reverse shock state
What happens in the refractory (irreversible) stage of shock?
Fourth stage. Progressive end organ dysfunction becomes irreversible and unresponsive to therpeutic interventions
- Tissue hypoxia worsens
- Anaerobic metabolism takes over
- Metabolic lactic acidosis alters pH
- Stasis of blood in capillaries
- Increased capillary pressure (anasarca)
- Fluid now shifts to extravascular spaces
- Decreasing venous return to heart
- Decreasing CO
- Peripheral vasoconstriction (SNS)
What are the signs and symptoms of refractory stage of shock?
- Depressed LOC (decreased cerebral blood flow)
- Hypotension (decreased CO)
- Tachycardia (SNS)
- Myocardial depression/bradycardia
- Cerbral ischemia (brain death)
- Central failure of SNS and loss of BP = Respiratory failure and cardiac arrest
What is disseminated intravascular coagulation (DIC)?
Disorder in which bleeding and clotting occur abnormally and simultaneously. Always caused by an underlying condition. Goal is aggressive treatment of underlying cause.
What is systemic inflammatory response syndrome (SIRS)?
Systemic activation of the inflammatory-immune response. Inflammation occurs in many organs and/or organ systems at once.
What is multiple organ dysfunction syndrome (MODS)?
When more than one organ system fails, usually respiratory first (ARDS), followed by others, infection, inflammation, ischemia. Carries 90% mortality rate.
What are the neurologic symptoms in compensated, progressive, refractory stages of shock?
Compensated: restless, irritable, apprehensive, oriented, verbal, subtle change in LOC
Progressive: confused, notable change in LOC, decreased response to stimuli
Refractory: unresponsive, severely decreased LOC, dilated non reactive pupils