22.3: Shock Drugs
By the end of this section, you should be able to:
- 22.3.1 Identify the characteristics of drugs used to treat anaphylactic, hypovolemic, and cardiogenic shock.
- 22.3.2 Explain the indications, actions, adverse reactions, and interactions of drugs used to treat anaphylactic, hypovolemic, and cardiogenic shock.
- 22.3.3 Describe nursing implications of drugs used to treat anaphylactic, hypovolemic, and cardiogenic shock.
- 22.3.4 Explain the client education related to drugs used to treat anaphylactic, hypovolemic, and cardiogenic shock.
Shock is a state of medical emergency in which tissues are not receiving enough oxygenated blood to sustain life. If not treated rapidly, decreased perfusion will cause hypoxia and eventually cell and tissue death. Because many different cells and tissues are at risk, cell and tissue death can lead to multiorgan failure and, eventually, death.
Anaphylactic Shock Drugs
Anaphylactic shock is a severe and life-threatening response to an allergen to which the body has a hypersensitivity. Typically, systemic vasodilation occurs, which causes shock and bronchoconstriction (often severe). Drugs are used to reverse bronchoconstriction and support hemodynamic stability.
Epinephrine
Epinephrine , a nonselective adrenergic agonist, is the most important drug used to treat anaphylactic shock. It causes sympathetic nervous system stimulation, which dilates the pulmonary bronchioles to open up airways and constricts blood vessels to increase blood pressure. Epinephrine acts very quickly and can decrease bronchoconstriction within 3–5 minutes. Epinephrine can be administered intramuscularly or intravenously depending on the acuteness of the situation. Table 22.8 earlier in the chapter is a drug prototype table for epinephrine use in emergency situations.
Nursing Implications
The nurse should do the following for clients receiving epinephrine intramuscularly or intravenously for anaphylactic shock:
- Place the client on continuous cardiac monitoring.
- Assess lung sounds prior to administration and frequently after administration.
- Monitor blood pressure frequently. (Blood pressure is often measured continuously when a client is in shock.)
- Monitor respiratory rate frequently.
- Monitor oxygen saturation continuously.
- Monitor level of consciousness.
- Have resuscitative equipment and drugs available.
- Provide client teaching regarding the drug. See below for client teaching guidelines.
Client Teaching Guidelines
In ventricular fibrillation, pulseless ventricular tachycardia, asystole, or pulseless electrical activity, the client will be unconscious. In anaphylaxis, the client may be unconscious.
If alert and oriented, the client receiving epinephrine should:
- Inform the health care team if they have a change in status (better or worse) after medication administration.
- Inform the health care team if they notice a change in their breathing.
Albuterol
Albuterol is a beta - adrenergic receptor agonist that causes bronchiole smooth muscle dilation, which opens up the bronchiole airways. Albuterol may be used in anaphylaxis if epinephrine does not fully open the airways. In anaphylaxis, it is administered as an inhaled nebulizer treatment.
Adverse Effects and Contraindications
Albuterol can cause paradoxical bronchospasm, tachycardia, and an immediate hypersensitivity reaction.
Hypersensitivity is the only contraindication to albuterol.
Table 22.14 is a drug prototype table for albuterol. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
|
Drug Class
Beta-adrenergic receptor agonist Mechanism of Action Directly stimulates beta receptors in the lungs, which causes smooth muscle dilation and opens airways |
Drug Dosage
For acute/severe bronchospasm: 2.5–5 mg via nebulizer every 20 minutes for 3 cycles; may repeat treatments every 1–4 hours as needed. |
|
Indications
Relief of bronchospasm Therapeutic Effects Causes bronchodilation |
Drug Interactions
Other short-acting sympathomimetic aerosol bronchodilators Epinephrine Monoamine oxidase inhibitors Tricyclic antidepressants Beta blockers Food Interactions No significant interactions |
|
Adverse Effects
Paradoxical bronchospasm Tachycardia Immediate hypersensitivity reaction |
Contraindications
Hypersensitivity |
Nursing Implications
The nurse should do the following for clients receiving albuterol via nebulizer for anaphylaxis:
- Assess lung sounds prior to administration and frequently after administration.
- Monitor blood pressure frequently. (Blood pressure is often measured continuously when a client is in shock.)
- Monitor respiratory rate frequently.
- Monitor oxygen saturation continuously.
- Monitor level of consciousness.
- Have resuscitative equipment and drugs available.
- Provide client teaching regarding nebulizer treatment.
- Provide client teaching regarding the drug. See below for client teaching guidelines.
Client Teaching Guidelines
The client receiving albuterol should:
- Hold the nebulizer mouthpiece between their teeth with their lips closed around it.
- Hold the nebulizer in an upright position.
- Understand that treatment often lasts 10–15 minutes.
- Inform the health care provider of chest pain or pressure or a feeling of rapid heart rate.
Isotonic Intravenous Solution
Anaphylactic shock causes fluids to shift from within the blood vessels (intravascular) to the tissues (extravascular). This can occur very rapidly and is the primary cause of the shock. Isotonic IV solutions have the same amount of sodium concentration as blood does.
Because fluid has shifted to the extravascular space in anaphylactic shock, there is not enough volume in the intravascular space to maintain blood pressure and tissue perfusion. Isotonic intravenous solution will increase volume, which then increases blood pressure.
In anaphylactic shock, 1–2 L of an isotonic IV solution such as normal saline should be administered rapidly (at the highest flow rate possible) as soon as an IV is established. After the initial IV fluid bolus, the client may need continuous IV fluids at a rapid rate to maintain blood pressure. Examples of isotonic IV solutions are normal saline and lactated Ringer’s.
Hypovolemic Shock Drugs
Hypovolemic shock occurs when the circulating volume of fluid has decreased so much that it affects tissue perfusion. The first priority in hypovolemic shock is to correct the underlying cause; for example, if the hypovolemia is caused by blood loss, measures should be taken to stop the blood loss, and the client should receive a blood transfusion as soon as possible. Intravenous fluid resuscitation is also used to increase cardiac output and stabilize blood pressure. The use of vasopressors (drugs that increase blood pressure) in hypovolemic shock is controversial and will not be included in this section.
In hypovolemic shock, 2 L of an isotonic IV solution should be administered as quickly as possible. After the initial fluid bolus, additional IV solution may be ordered to maintain blood pressure.
Cardiogenic Shock Drugs
Cardiogenic shock occurs when the myocardium is not able to pump effectively enough to maintain cardiac output. This can be due to ischemia, infarction, or other causes. Cardiogenic shock is treated with vasopressors and SNS stimulation. Cardiac output must be increased in order to restore adequate tissue perfusion. Medications used in cardiogenic shock include dopamine, dobutamine, and norepinephrine. Dopamine and dobutamine are covered in a previous section in this chapter. Norepinephrine can be used for other types of shock, but it is included here because of its effects on the heart.
Norepinephrine
Norepinephrine is an alpha-1 receptor agonist and a moderate beta-1 receptor agonist . Alpha-1 receptors are located in the smooth muscle around blood vessels. When these receptors are stimulated, they cause muscle contraction, which causes vasoconstriction. Beta-1 receptors are located in the heart; when they are stimulated, they cause increased heart rate and force of contraction.
Adverse Effects and Contraindications
Norepinephrine can cause cardiac arrhythmias, severe peripheral ischemia in clients who are hypovolemic, gangrene in clients with occlusive or thrombotic vascular disease (in high doses), and rebound hypotension after discontinuation. Norepinephrine may cause decreased sensitivity to insulin, so clients with diabetes may need their glucose levels monitored more frequently as well as increased doses of antidiabetic medications.
Extravasation of norepinephrine at the IV site can cause tissue necrosis.
There are no contraindications for norepinephrine.
Table 22.15 is a drug prototype table for norepinephrine. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
|
Drug Class
Alpha/beta antagonist Mechanism of Action Stimulates alpha- and beta-adrenergic receptors, thereby increasing blood pressure, heart rate, and force of contraction |
Drug Dosage
For profound hypotension or shock: Initial dose: 8–12 mcg/min, titrated to blood pressure. Typical maintenance dose: 2–4 mcg/min. Hypovolemia must be corrected before initiating norepinephrine infusion. |
|
Indications
Severe acute hypotension Shock Therapeutic Effects Increased blood pressure Increased heart rate and force of contraction |
Drug Interactions
Monoamine oxidase inhibitors (can lead to profound hypertension) Tricyclic antidepressants (can lead to profound hypertension) Halogenated anesthetics (can cause ventricular tachycardia or fibrillation) Food Interactions Caffeine |
|
Adverse Effects
Tissue ischemia in clients who are hypovolemic (severe peripheral ischemia) Gangrene in clients with occlusive or thrombotic vascular disease (in high doses) Rebound hypotension after discontinuation Cardiac arrhythmias |
Contraindications
None |
Nursing Implications
The nurse should do the following for clients receiving norepinephrine:
- Place the client on continuous cardiac monitoring.
- Monitor heart rate frequently.
- Monitor level of consciousness.
- Have resuscitative equipment and drugs available.
- Assess the IV site frequently.
- Correct hypovolemia before giving norepinephrine.
- Provide client teaching regarding the drug. See below for client teaching guidelines.
Client Teaching Guidelines
The client receiving norepinephrine should:
- Inform the health care team if they have a change in status (better or worse) after medication administration.
- Inform the health care team if they have discomfort or pain at the IV site.