Chapter 2 Care of the Critically Ill Patient



Care of the Patient with Acute Coronary Syndrome

Learning Outcome 1

Explain acute coronary syndrome.

1. Acute coronary syndrome (ACS)

Acute coronary syndrome (ACS) is an inclusive term for conditions that cause chest pain due to insufficient blood supply to the heart muscle. The patient will have stable chest pain and can progress to unstable chest pain and eventually the infarction or death of the myocardial tissue. ACS covers the spectrum of clinical conditions ranging from ST-segment elevation myocardial infarction (STEMI); non-ST-segment elevation (NSTE) ACS, which includes the diagnosis of unstable angina; and NSTE myocardial infarction (NSTEMI).

• An all-inclusive term that describes a progression of coronary events

o ST-segment elevation myocardial infarction (STEMI)

o Non-ST-segment elevation (NSTE) ACS, which includes the diagnosis of unstable angina

o NSTE myocardial infarction (NSTEMI)

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Figure 6-2 Atherosclerosis

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Figure 6-3 Ruptured plaque.

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2. Risk factors for coronary artery disease (CAD)

The following sections present risk factors that are and are not modifiable.

• Modifiable—factors that the client can control

o Tobacco smoke

o Hypertension

o Physical activity

o Obesity

o Dyslipidemia

o Diabetes mellitus

[Table 6-1 Body Mass Index]

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• Nonmodifiable—factors that the client cannot control

• Age: Death generally occurs over age 65

• Gender: Men are at greater risk than women

• Heredity: Children of parents with heart disease are at greater risk

• Other risk factors

o Stress

o Alcohol consumption

o Hormone replacement therapy (HRT)

Learning Outcome 2

Differentiate among different types of acute coronary syndrome.

1. Angina pectoris—“strangling of the chest”

Angina pectoris is a general medical term used to define types of chest pain caused by myocardial ischemia. Thrombus formation and further plaque formation eventually narrow the coronary arteries, causing ischemia and death of myocardial tissue. Angina can be classified into three different phases: stable, unstable, and variant. The angina that is of more concern to the development of ACS is the unstable angina prototype.

• Stable: Occurrence is predictable, on exertion

• Variant angina: Episodes of chest pain that occur at rest

• Unstable angina: Pain that occurs more often and in unpredictable patterns

• Unstable angina is considered to be present in patients with ischemic symptoms suggestive of an ACS and no elevation in troponin, with or without ECG changes indicative of ischemia (e.g., ST segment depression or transient elevation or new T wave inversion). Since an elevation in troponin may not be detectable for up to 12 hours after presentation, UA and NSTEMI are frequently indistinguishable at initial evaluation.

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2. Myocardial infarction

An MI occurs when the heart muscle is abruptly deprived of oxygen. When the heart is deprived of oxygen, it proceeds through several phases of tissue injury. The first phase is the area of ischemia. If treatment is not immediate the tissue damage will continue on to injury and then necrosis.

Figure 6-4 The evolution changes in acute MI.

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• Occurs when the heart muscle is abruptly deprived of oxygen

• Ischemia is the first phase, resulting in lack of oxygen

• Injury occurs when tissue is injured from lack of oxygen

• Necrosis is death of myocardium tissue.

Learning Outcome 3

Describe emergent assessment and collaborative management of the person with chest discomfort.

1. Assessment: Pain

• Classic sign is pain

• Described as severe, crushing pain; squeezing sensation

• Pain radiates down the left arm or up to the jaw

• Pain is not relieved by rest or nitroglycerine

• Atypical signs and symptoms (S/S): nausea, vomiting, diaphoresis, palpitations, dyspnea

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2. Collaborative management: Emergent nursing care

Upon arrival to the emergency department (ED), the nurse needs to perform the following interventions to alleviate pain and anxiety and increase the myocardial oxygen level:

• Place patient in semi-Fowler’s position

• Insert an intravenous line for administration of emergency medications

• Initiate medications and treatment

• Assess vital signs frequently

• Obtain ECG within first 10 minutes of arrival

• Obtain blood for laboratory test

3. Collaborative management: Emergency meds

• Aspirin is given first—treatment of choice

• Nitroglycerin—if systolic blood pressure (BP) is above 90

• Administer supplemental oxygen

• Administer morphine sulfate IV

• Beta blockers

• Angiotensin-converting-enzyme inhibitor (ACE) inhibitor if signs of congestive heart failure (CHF)

4. Collaborative management: Diagnostic tests

Diagnostic criteria are extremely important for the patient with an MI and ACS. Results help to determine the location of the muscle damage as well as the extent of the damage. Several diagnostic tests are included as the mainstay of MI or ACS diagnosis:

• ECG: Common waveforms indicative of myocardial infarction

• Laboratory studies

• Chest x-ray: Used to determine signs of impending heart failure

• Exercise testing with ECG continuous monitoring

• Cardiac catheterization

5. Collaborative management: 12-lead ECG

Ischemia. Myocardial ischemia is the result of an imbalance between the myocardial oxygen supplies versus the myocardial oxygen demand. There are several key ECG changes that coincide with myocardial ischemia. The first is a T-wave inversion. Other ECG changes are an ST-segment depression of greater than 0.5 mm, an ST segment that remains on the baseline longer than 0.12 second, and inverted U waves.

Injury. Myocardial injury is most often indicated by ST-segment elevation of 1 mm or more above the baseline. The T wave may also become taller and pointed in configuration. There is also symmetric T-wave inversion.

Infarction. Infarction is suspected when the ECG shows either new Q waves or a deepening of existing Q waves. A Q wave that is either 0.04 second wide or that has a depth of at least 25% of the size of the R wave is considered pathologic.

• 12-lead electrocardiogram (ECG)—most crucial within first 10 minutes of arrival

• Prolonged ST-segment elevation or new Q waves indicates STEMI

• NSTE may present with ST depression, T-wave inversion

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Learning Outcome 4

Evaluate various laboratory tests used to determine if a person is experiencing an acute coronary event.

1. The patient who is suspected of having acute myocardial injury should have blood drawn to measure blood counts, cardiac enzyme and isoenzymes released when myocardial inflammation, injury, and necrosis are present. This should be performed within 10 minutes of arrival to the ED and obtained serially. Laboratory tests often include creatinine kinase, troponin, myoglobin, and C-reactive protein.

2. Creatinine kinase

Creatinine kinase (CK) may not be helpful in immediate diagnosis of an MI due to the 4 to 6 hours needed to see a significant rise. It is believed that the CK levels are more important in gauging the size and timing of an acute MI than the actual diagnosis. The CK levels are further differentiated by bands, signifying the different muscles affected. The CK-MB (CPK2) is used for myocardial damage.

• CK rises in 4–6 hours post MI.

• CK levels peak in 12–24 hours and return to normal in 72–96 hours.

• CK-MB levels increase in 2–6 hours.

• CK-MB levels peak at 18 hours and return to normal within 24 hours.

• CK-MB is positive when greater than 3% of the total CK.

3. Troponin T and I

Cardiac troponin assays are very useful in the diagnosis of an acute MI.

Myoglobin

Damaged cardiac cells rapidly release myoglobin into the bloodstream. The drawback is that myoglobin lacks cardiac specificity; therefore, it needs to be used in conjunction with other definitive laboratory tests. A doubling of the myoglobin level in 2 hours strongly suggests MI.

Learning Outcome 5

Differentiate between fibrinolysis and PCI for emergent reperfusion of the cardiac patient.

1. Fibrinolysis

Fibrinolysis is achieved with the use of tissue plasminogen activators (tPA) to quickly lyse the thrombus. These thrombolytic drugs are the most commonly used to treat acute coronary syndromes. To be a candidate, the patient must have STEMI and have developed the symptoms within 12 hours of the therapy. The most commonly used thrombolytic drugs include Alteplase (Activase), Retaplase (Retavase), and Tenecteplase (TNK-tPA). Ideally, the thrombolytic should be administered within 30 minutes of arrival to the ER or within 3 hours of symptom onset, although benefits have been seen when these drugs are administered up to 12 hours afterward; giving these drugs after 24 hours, however, can be harmful.

• Dissolves clot in the coronary artery, restoring blood flow

• Must have STEMI and symptom onset < 12 hours ago

• Common drugs: Alteplase, Retaplase, Tenecteplase

• High risk of bleeding

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Percutaneous coronary intervention (PCI)

• Coronary arteriography and percutaneous balloon angioplasty (PTCA)

• Goal: reperfuse myocardium

• Balloon widens artery

• Metal stent placed to maintain vessel patency

• Requires antiplatelet therapy post stent for minimum of 6 months

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2. Stent placement following angioplasty]

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1. [Coronary artery before angioplasty with stent insertion]

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Learning Outcome 6

Describe nursing management of the patient post angioplasty with stent placement.

1. Monitor for complications

After the procedure the patient needs to be monitored for signs and symptoms of myocardial ischemia, thrombosis, and bleeding. Myocardial ischemia and possible thrombosis are assessed by chest pain; ST-segment changes, especially elevation on the telemetry; and shortness of breath. Changes in vital signs can include decreased oxygen saturation, a drop in BP, or a decrease or increase in heart rate (HR). Dysrhythmias are assessed, especially if they cause hemodynamic compromise. The most common dysrhythmias are ventricular tachycardias, atrial bradycardias, and heart blocks.

• Myocardial ischemia

• Thrombosis

• Bleeding

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2. Preventing bleeding

Bleeding can include hematuria as well as bleeding from the catheterization site or other body orifices. Vital signs can indicate more serious internal bleeding problems. The patient’s hemoglobin, hematocrit, and platelet levels should also be monitored. A newer device to maintain hemostasis after a PCI is the collagen sheath or patch (Figure 6-14). The most commonly used are the Vaso-seal and Angioseal. This is a secure method of achieving hemostasis following a femoral artery puncture. It allows the patient to achieve early ambulation and hospital discharge. The patient needs to be monitored for peripheral thrombosis and ischemia in the leg used for the procedure. Any change in pulses from the pre-procedure assessment should be reported immediately to the interventionalist.

• Hematoma at insertion site = sign of bleeding

• Retroperitoneal bleed most common

• Device placed at insertion site to prevent bleeding

• S/S of bleeding may include:

o Fever, swelling, oozing, or extension of bruising at catheter site

3. Discharge teaching

The patient should report any signs or symptoms of an MI or angina to the physician. The patient also needs to notify the interventionalist if any signs or symptoms of infection or bleeding occur. These can include fever, swelling, oozing, or extension of bruising around the catheter insertion site. Pain, numbness, or tingling of the leg used for the procedure must also be reported.

• Patients should report S/S of MI or bleeding

• Should also report:

o Pain, numbness, or tingling of the leg used for the procedure

Learning Outcome 7

Discuss care of the patient following coronary artery bypass surgery.

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1. Collaborative management in the postoperative phase

During the postoperative period the patient must be monitored carefully because changes are subtle and occur rapidly. It is important for the nurse to anticipate the possible complications so the proper interventions can be initiated in a timely manner to ensure a positive outcome for the patient. Post-op care involves: pulmonary management; hemodynamics; assessing for bleeding, neurologic status, renal status, and gastrointestinal (GI) status; pain control; infection prevention.

• Monitor frequently

• Anticipate possible complications

2. Pulmonary management post CABG

Pulmonary dysfunction is a common complication of CABG surgery. Patient history and intraoperative complications must be considered for proper management postoperatively. Some patients will be intubated and mechanically ventilated when they first arrive in the intensive care unit. Many patients come out extubated.

• Desired outcomes: early extubation, adequate ventilation and oxygenation

• Adequate and frequent assessment

• Nurse must assess for readiness for extubation

3. Hemodynamics: BP control

The nurse needs to constantly assess for cardiac instability during the immediate postoperative period. The intensive care nurse must monitor the interrelationship between heart rhythm and rate, preload, afterload, contractility, and myocardial compliance to achieve a positive outcome. BP must be maintained within ordered parameters to provide tissue perfusion and prevent disruption of the surgical anastomosis. The nurse must monitor the volume in the circulatory system, which is reflected by the right arterial pressure (RAP) and pulmonary capillary wedge pressure (PCWP).

• Assess and address low or high BP

• Low BP: give fluid, inotropes, or vasopressor

• High BP: give nitroprusside, nitroglycerin

4. [Treatment of high blood pressure after cardiac surgery]

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5. Hemodynamics: Dysrhythmia control

Dysrhythmias are common after CABG surgery. The patient will be constantly monitored by a bedside monitor. The nurse needs to treat the patient, not the monitor. Effectiveness of BP and CO should be considered when evaluating the dysrhythmia. Because surgeons place epicardial pacer wires during surgery, temporary pacing can be instituted to override an improper intrinsic rhythm so CO and BP can be maintained. The intensive care nurse needs to utilize the protocols of the individual institution as well as current advanced cardiac life support protocols.

• Common post CABG

• Ventricular first 24 hours post-op

• Supraventricular 24 hours to 5 days post-op

• A-fib common: treat with Amiodarone, beta blockers, pacing

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6. Bleeding

Many factors need to be considered when assessing the patient’s potential for bleeding. Patients who were on anticoagulants and antiplatelet agents prior to surgery may be at risk for postoperative bleeding. These should be discontinued if the CABG is an elective case.

• Assess for bleeding

o Chest tube drainage Q 15 minutes then hourly

o S/S hypovolemia, Hgb/Hct

• Assess for tamponade

o Lack of chest tube drainage

o Decreased BP, narrowed pulse pressure, increased HR

o Jugular venous distention, elevated CVP, muffled heart tones

7. Post-op organ system management

Decreases in CO can affect organ function. It is important for the nurse to know postoperative organ system complications. Post-CABG patients are at risk for neurological complications. Cerebrovascular accidents (CVAs) can be the cause of hypoperfusion or an embolic event during or after surgery. There is about an 8% risk for postoperative renal complications. Renal insufficiency can be caused by advanced age, hypertension, diabetes, decreased left ventricular function, and the length of time on cardiopulmonary bypass. Complications can include peptic ulcer disease, perforated ulcer, pancreatitis, cholecystitis, bowel ischemia, and liver dysfunction. The nurse should monitor the patient’s bowel sounds, abdominal distention, and nausea and vomiting. The patient will have a nasogastric tube in place, so placement and assessment of the amount, color, and characteristics of drainage should be noted.

• Neurologic status

o Risk for CVA is 2.5%

o Complete thorough neurologic assessment

• Renal status

o U/O should be 0.5 mL/kg/hr

o Monitor hourly for 24–48 hours

o Draw BUN/creatinine

• GI management

o Complications include: peptic ulcer disease, perforated ulcer, pancreatitis, cholecystitis, bowel ischemia, and liver dysfunction

o Risk factors for complications: age over 70, history of GI disease, alcohol abuse, emergent operation, prolonged cardiopulmonary bypass, postoperative hemorrhage, use of vasopressors, and low postoperative CO

o Administer to prevent complications: antiemetics, histamine-blocking agents and proton pump inhibitors

8. Manage post-op pain

Poorly controlled pain can lead to cardiovascular consequences. The HR and BP can increase and the blood vessels constrict, causing an increase in cardiac workload and myocardial oxygen demand. Effective pain control is important for patient comfort, hemodynamic stability, and to prevent pulmonary complications.

• Analgesics

• Positioning

• Distraction and relaxation techniques

9. Prevent infection

The nurse must monitor for signs and symptoms of infection. The source of infection can be respiratory or from the incisions. The incidence of sternal and leg incisions is less than 3%. Risk factors for infection include diabetes, malnutrition, and patients undergoing emergent or prolonged surgery.

• Assess for S/S of infection

• S/S: Increased temperature, drainage from incision, increased color in sputum, redness at the incision site

Learning Outcome 8

Prioritize discharge teaching for the patient who has had an acute coronary event.

1. Discharge education priorities for ACS

The care of the patient with ACS not only includes the hospitalization, but many months of recuperation and rehabilitation. The patient will be monitored by the cardiologist and nursing staff, and the plan of care will include medications, anxiety control, exercise management, and nutrition management. As with any program that involves a lifestyle change, frequent contact with health care providers is highly suggested to provide time for evaluation and encouragement to continue with the promoted changes.

• Implement the ABCDE to assist with discharge

o A = Aspirin and anti-anginals

o B = Beta blockers and blood pressure

o C = Cholesterol and cigarettes

o D = Diet and diabetes

o E = Education and exercise

1. Pharmacologic therapy

The patient will be discharged from the hospital after an acute coronary event on multiple medications. These medications will include ones that control platelet adhesion, prevent the expenditure of myocardial oxygen, and prevent ventricular remodeling so that the complication of congestive heart failure is less likely to develop.

• Anti-anginals: nitroglycerin

• Antiplatelets: ASA

• Decrease myocardial O2 demand: beta blockers

• Prevent ventricular remodeling: ACE inhibitors

• Cholesterol reduction: HMG-COA reductase inhibitors, nicotinic acid

2. Pharmacologic therapy (continued)

• Unless contraindicated, the patient experiencing an MI should receive:

o Early administration of aspirin and beta blocker

o Timely reperfusion (thrombolysis or percutaneous intervention)

o Aspirin and beta blocker at discharge

o ACE inhibitor or angiotensin receptor blockers (ARBs) at discharge

o Smoking cessation counseling

o Lipid-lowering agent

3. Anxiety and depression management

Depression has emerged as a risk factor for ACS. It has been estimated that up to 30% of patients experience depression after a coronary event (Arthur, 2006). Depression is associated with reduced participation in cardiac rehabilitation programs. The thoughts of a person who is depressed often accompany feelings of worthlessness, hopelessness, and even death. Anxiety often coexists with depression in a patient with ACS. Anxiety may present itself with feelings of tension and impending catastrophe as well as insecurity, inadequacy, and helplessness. It is important for the nurse to understand depression and anxiety in order to enhance patient recovery from the coronary event. Patients often feel that they are to blame for their health situation and that they have no control over what is going to happen over the course of rehabilitation.

Patients’ anxiety and depression can be controlled by medications, but often they feel that having a nurse or medical team member keeping them informed of the situation gives them more control.

• Approximately 30% of patients experience depression after a coronary event

• Anxiety and depression coexist in patient with ACS

• Psychoeducational programs:

o Teach patients stress management and relaxation techniques

o Assist patients in attaining the appropriate coping mechanisms

o Assist patients to adapt and use the appropriate defense mechanisms for healthy control of depression and anxiety

4. Physical activity

Physical activity provides a multitude of benefits for the cardiac patient. Aerobic exercise has been found to positively affect lipid levels, hypertension, diabetes, weight, and obesity. Resistance training has a positive correlation with muscle mass, bone density, and functional capacity. Physical activity also has a positive correlation with psychological health.

The particular goal of a cardiac rehabilitation program is to promote lifestyle changes and secondary prevention of CHD. The programs alleviate the psychological and physiological constraints in the form of reducing risks, managing symptoms, and having patients regain control of their lives. The programs consist of a monitored exercise program and an educational program on lifestyle changes. The length of the programs varies from program to program.

Patients are often confused about returning to sexual relations after either an MI or a cardiac surgical intervention. Most patients can return to a healthy sexual life after a cardiac event. If a patient successfully finishes a cardiac rehabilitation program, the risk of experiencing an additional risk as a result of sexual activity is 20 in a million. The energy expended during a sexual encounter is equivalent to walking at a fast pace on level ground.

• 30 minutes of moderate exercise 5 days/week

• Cardiac rehab:

o Promote lifestyle changes

o Appropriate exercise

• Resuming sexual activity

o Resume 6–8 weeks post MI and after treadmill test

o Avoid sexual activity: after eating a heavy meal or excessive alcohol intake, in extreme temperatures, or while wearing restrictive clothes

5. Nutrition

• Dietary changes

o Decrease lipids

o Decrease hypertension (HTN)

o Control diabetes

o Decrease obesity

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