Complications: Extended Recovery Period
Complications of cardiac surgery may occur at many points along the path to recovery. This chapter is a continuation of Chapter 10 and deals with complications that tend to occur later in the hospital stay, often after patients are transferred out of the intensive care unit (ICU). However, complications discussed in Chapter 10 may occur late in the hospital stay and complications discussed in this chapter may occur early. Either way, it is important to be aware of potential complications and recognize them early so treatment can be started. In addition, stroke is a major complication of cardiac surgery and can be life changing and very distressing to the patient and family. Stroke may occur at any point in a patient’s recovery and is discussed in Chapter 14.
Patients who have extended hospital stays may also experience other complications related to hospitalization. These complications are outside the scope of this book, but it is important to prevent these complications or, if that is not possible, to recognize and treat them if they do occur. These complications may include pressure ulcers; complications of prolonged ventilation, such as tracheotomy; loss of muscle mass and debilitation; failure to thrive; poor nutrition and need for tube feeding; and infections, including urinary tract infection and various infections with drug-resistant organisms.
Objectives
In this chapter, you will learn:
1. Prevention and treatment of common post-op cardiac surgery complications that may occur later in a patient’s hospital stay
2. Assessment, laboratory, and x-ray findings that may signal potential complications
CONDUCTION PROBLEMS
A number of arrhythmias and other conduction problems may arise after cardiac surgery. Arrhythmias may originate in the atria, the atrioventricular (AV) node, or the ventricles. Any arrhythmia has the potential to decrease cardiac output, which is detrimental to patients after heart surgery. It is imperative that nurses be able to recognize arrhythmias and know what actions to take.
Atrial Fibrillation
Atrial fibrillation is a common complication of cardiac surgery and frequently prolongs hospital stay. (See Chapter 7 for a description of atrial fibrillation.) It occurs in 20% to 50% of cardiac surgery patients (Coventry, 2014). The incidence varies with the type of surgery, occurring more frequently after valve surgery or combination coronary artery bypass and valve surgery. This is because of the enlargement of the atria due to valve disease as well as incisions made in the atria while accessing a valve for either repair or replacement. This disruption of atrial tissue predisposes the patient to developing atrial fibrillation.
Atrial fibrillation typically develops 1 to 3 days after surgery. The risk increases with age, with elderly patients at highest risk of developing post-op atrial fibrillation. Other risk factors include preexisting atrial arrhythmias, previous cardiac surgery, low serum potassium or magnesium, valvular heart disease, and atrial enlargement. Manipulation of atrial tissue, fluid overload, electrolyte shifts, cooling, inflammatory response due to cardiopulmonary bypass, ischemia, and pericarditis increase the likelihood of atrial fibrillation.
Atrial fibrillation causes a decrease in cardiac output of up to 20% due to loss of atrial kick. Many patients do not tolerate such a decrease in cardiac output after cardiac surgery, so the goal is to restore normal sinus rhythm, rather than merely maintain a controlled rate. Patients who have been in atrial fibrillation for more than 6 months prior to surgery will most likely not be successfully converted into normal sinus rhythm, so the goal for these patients will be to control the ventricular response rate to less than 100 beats per minute.
Prevention
There is evidence that the routine administration of magnesium sulfate prior to and immediately after cardiac surgery may decrease the rate of atrial fibrillation. Daily administration of metoprolol (Lopressor), 25–50 mg orally, has been shown to decrease the rate of atrial fibrillation after surgery. When giving metoprolol (Lopressor), blood pressure and heart rate should be monitored, since beta-blockers cause a decrease in both. Prophylactic oral amiodarone (Cordarone), 200–600 mg, may be given daily after cardiac surgery to patients at highest risk of developing post-op atrial fibrillation. Patients taking amiodarone (Cordarone) should be monitored for bradycardia, prolonged QT interval, and heart blocks.
Assessment
After cardiac surgery, heart rhythm should be continuously monitored. Vital signs should be checked, especially blood pressure, heart rate, respiratory rate, and pulse oximetry. When in atrial fibrillation, the patient needs to be monitored for hemodynamic stability. Signs of hemodynamic instability include hypotension, changes in mental status, impaired peripheral perfusion, and decreased urine output. In addition, some patients become short of breath or lightheaded when in atrial fibrillation and some patients feel palpitations. Patients who have converted to atrial fibrillation should be assisted to bed or asked to remain in bed until their response can be determined.
Diagnostics
A 12-lead electrocardiogram (ECG) should be performed for any patient who goes into atrial fibrillation. Serum electrolytes, especially potassium and magnesium, may be drawn as well so that these electrolytes may be quickly replaced if blood levels have fallen below parameters specified by the physician.
Intervention
Patients in atrial fibrillation are treated either by restoring normal sinus rhythm or by controlling the ventricular response rate. The decision of how to treat is made based on the patient’s history and hemodynamic stability while in atrial fibrillation. This decision should be made by the physician, who should be notified as soon as the patient goes into atrial fibrillation. Patients who are hemodynamically unstable need to be treated immediately. More time may be taken to try various treatment methods for patients who are hemodynamically stable and tolerating the rhythm.
Synchronized cardioversion is commonly used to convert a patient back into normal sinus rhythm. This involves the use of electrical current synchronized to the patient’s QRS complex. A patient who is hemodynamically unstable in atrial fibrillation should have immediate synchronized cardioversion. Cardioversion is more successful if antiarrhythmic medications are given first. For patients who are not hemodynamically unstable in atrial fibrillation, an antiarrhythmic medication may be tried first, followed by synchronized cardioversion if the patient does not convert to normal sinus rhythm with medical therapy alone. Antiarrhythmic medications include amiodarone (Cordarone) and ibutilide (Corvert). Metoprolol (Lopressor) and diltiazem (Cardizem) may also be used.
For some patients, especially those with a history of permanent atrial fibrillation prior to surgery and those who are hemodynamically stable, the decision is made to control the rate of atrial fibrillation rather than try to convert to normal sinus rhythm. Also, if attempts to convert to normal sinus rhythm are unsuccessful, rate control may be the best option. Keeping the ventricular response rate less than 100 beats per minute increases ventricular filling time and thus increases cardiac output. If rate control is desired, beta-blockers, calcium channel blockers, and digoxin are most commonly used.
CLINICAL ALERT! Patients in atrial fibrillation for more than a few hours need anticoagulation due to stasis of blood in the atria and potential for forming clots, which then embolize to other areas of the body. Usually, a heparin infusion is administered until warfarin can be given to raise the international normalized ratio (INR) to between 2 and 3.
NURSING IMPLICATIONS: The cardiac surgery nurse needs to be aware of the heart rhythm when caring for patients. New atrial fibrillation should be recognized and patient assessment for hemodynamic stability should take place immediately. The information gathered during the assessment should be relayed to the physician so a treatment plan may be decided. The nurse should anticipate immediate synchronized cardioversion for unstable patients.
FAST FACTS in a NUTSHELL
Atrial fibrillation is very common after cardiac surgery and can cause a decrease in cardiac output and hemodynamic instability. When a patient is in atrial fibrillation, action should be taken to convert the patient to normal sinus rhythm or control the ventricular response rate.
Conduction Blocks
During cardiac surgery, the AV node may be damaged either by surgical manipulation or by edema. This may lead to the development of various types of heart block (type I, type II—Wenckebach or Mobitz II, or complete heart block). These blocks may be transient, especially if caused by edema, but may cause a dangerously low heart rate and decrease in cardiac output.
Prevention
All patients should have heart rate and rhythm monitored after cardiac surgery. The physician should be notified of any heart block so that appropriate treatment may be initiated.
Assessment
As described earlier for atrial fibrillation, patients who develop a conduction block should be assessed for hemodynamic stability. Vital signs should be taken, mental status and alertness should be assessed, and patients’ subjective feeling of well-being should be determined. It is important to discern whether or not tissues are being perfused.
Diagnostics
A 12-lead ECG should be performed to determine the exact nature of the conduction block.
FIGURE 13.1 Pacing using epicardial pacing wires.
Intervention
Patients who develop a conduction block and experience hemodynamic instability should be paced, as ordered by a physician. If epicardial pacing wires are in place, these wires should be attached to a pacemaker generator and pacing should begin at a rate sufficient to perfuse the tissues and maintain cardiac output (Figure 13.1). If there are no epicardial pacing wires and the patient has a low blood pressure or other signs of severe hemodynamic instability, transcutaneous pacing should be initiated. Transcutaneous pacing is painful. Pain medication should be administered per physician’s order and placement of a transvenous pacing wire should take place as soon as possible. For patients who are less emergent, a transvenous pacing wire may be placed and transvenous pacing initiated without first pacing transcutaneously.
If a patient requires pacing and the conduction block does not resolve within a day or two, a permanent pacemaker may be required. If needed, a permanent pacemaker will be placed prior to discharge.
NURSING IMPLICATIONS: Assessment of patient stability should occur immediately if a patient develops a conduction block. The physician should be notified immediately if a patient becomes bradycardic or hemodynamically unstable with a conduction block. The cardiac surgery nurse should anticipate when pacing may be ordered and gather necessary supplies.
FAST FACTS in a NUTSHELL
Conduction blocks affecting the AV node occur frequently after cardiac surgery and may be transient or permanent. A low heart rate with hemodynamic instability requires pacing.
Ventricular Arrhythmias
Premature ventricular complexes (PVCs), ventricular tachycardia (VT), or ventricular fibrillation (VF) may occur after cardiac surgery, but are less common than atrial dysrhythmias. PVCs are common and not usually worrisome as long as serum potassium and magnesium are maintained at normal levels. Transient VT is also common and may be related to reperfusion injury. Ventricular arrhythmias are more common in patients with recent myocardial infarction (MI) or perioperative MI, poor left ventricular function, prolonged cardiopulmonary bypass time, and need for inotropes or an intraaortic balloon pump post-op.
Prevention
Maintaining serum potassium above 4 mg/dL and serum magnesium above 2 mg/dL will prevent some ventricular arrhythmias. Some surgeons prefer to keep serum potassium higher (4.5 or 5 mg/dL) to prevent arrhythmias.
Assessment
Patients who develop ventricular arrhythmias should be immediately assessed for hemodynamic stability.
CLINICAL ALERT! Patients who experience hemodynamically unstable ventricular arrhythmias require immediate intervention using advanced cardiac life support (ACLS) protocols to prevent death.
Diagnostics
Patients who develop PVCs or VT and who are stable may benefit from a 12-lead ECG to determine the exact nature of the arrhythmia. Use of the atrial epicardial lead to determine atrial versus ventricular origin of any tachyarrhythmia is recommended, as outlined here (Drew et al., 2004):
FIGURE 13.2 One of the atrial epicardial pacing wires can be used to obtain an atrial electrogram. This aids in differentiating tachycardias of supraventricular from those of ventricular origin.
• The atrial electrogram can be recorded with the bedside monitor or with a standard 12-lead ECG machine (Figure 13.2). The simplest way to record an immediate atrial electrogram at the bedside is to unsnap the chest (V) lead wire from the patient’s chest and hold it against the tip of an atrial epicardial pacemaker lead wire so that metal is touching metal.
• Rubber gloves should be worn when handling epicardial pacemaker leads because a small amount of current traveling up the wire directly to the heart can induce VF in a vulnerable patient (Drew et al., 2004).
• The atrial electrogram magnifies atrial activity in a rhythm strip, showing even P waves that are buried in a QRS complex. For example, in a patient with a preexisting bundle branch block, it can be difficult to tell if a tachycardia is atrial fibrillation with rapid ventricular response or VT, but an atrial electrogram can show if there is atrial activity.
Serum potassium and magnesium should also be drawn. Patients who are hemodynamically unstable require immediate intervention and treatment should not be delayed to obtain a 12-lead ECG. Serum electrolytes should still be drawn while other interventions are taking place.
Intervention
PVCs or VT occurring in patients who are hemodynamically stable may be treated by finding and fixing the underlying cause. This may include searching for evidence of ischemia or replacing serum potassium and magnesium. Inotropes should be avoided in patients with ventricular arrhythmias. For VT, an antiarrhythmic medication such as amiodarone (Cordarone) or lidocaine may be ordered to convert the rhythm to normal sinus rhythm. For patients who develop hemodynamically unstable VT or VF, immediate action must be taken following ACLS protocols.
NURSING IMPLICATIONS: Serum magnesium and potassium should be kept within ordered parameters. Nurses should be alert to potentially life-threatening rhythm changes and take immediate action.
FAST FACTS in a NUTSHELL
Ventricular arrhythmias are less common than atrial arrhythmias but are more life-threatening. The bedside nurse should be ready to follow ACLS protocols to restore a normal rhythm.
NEUROLOGICAL DYSFUNCTION
Neurological complications after cardiac surgery can be very severe, affecting mortality and quality of life. Up to 50% of patients may experience some cognitive impairment during the first week following cardiac surgery and many still have cognitive impairment 6 weeks after surgery. Neurological complications increase the likelihood a patient will be discharged to a rehabilitation facility or long-term care facility instead of to home. Risk factors include advanced age (older than 70 years), history of pulmonary disease or hypertension, diabetes, history of unstable angina or neuro deficits, history of excessive alcohol consumption, post-op dysrhythmias, and prior cardiac surgery. Aortic atherosclerosis and carotid artery disease are also risk factors because pieces of plaque can break free during surgery and embolize into cerebral arteries. Carotid artery disease, which limits blood flow, may also contribute to cerebral ischemia during low flow states.
Neurological complications following cardiac surgery fall into two categories. The first category (type I) includes stroke, transient ischemic attack (TIA), focal deficits, and coma. The second category (type II) includes confusion, agitation, decline in intellectual functioning, disorientation, and memory deficits. Type I complications come with significant mortality and greatly increase hospital stay. Type II complications are more common and have a lower mortality rate; they also may increase hospital length of stay. Collectively, type II complications are often referred to as encephalopathy. Stroke is covered in Chapter 14.
Mild cognitive decline is common after surgery and may include memory deficits and difficulty with problem solving, attention, and ability to learn. Most patients report improvement within 1 to 2 months after surgery.
Prevention
For high-risk patients, there are preventative strategies that may be employed in the operating room. For example, avoiding aortic manipulation in patients with aortic atherosclerosis can decrease risk. Nurses also play a large role in prevention of neurological complications by avoiding hyperthermia during rewarming, post-op hypotension, and hyperglycemia, all of which may increase the risk of these complications.
Assessment
Neuro assessments should be performed routinely on all cardiac surgery patients. Stroke should be suspected if the patient fails to awaken, follow commands, or move extremities when sedation is discontinued after surgery. Focal deficits should also be noted: facial droop, weakness on one side, aphasia, visual changes, or pupil changes. Unfortunately, assessment is often difficult due to emergence from anesthesia and response to various medications. Patients suspected of having a stroke should be seen by a neurologist and undergo brain imaging to confirm the diagnosis. (See Chapter 14 for more information.)
Post-op encephalopathy is more difficult to diagnose and to manage. These patients may experience delirium, demonstrated by inattention, cognitive impairment, memory deficits, disorientation, perceptual changes, and inappropriate speech. These acute changes may also be accompanied by agitation. Agitation is extreme vocal or motor behavior that is unsafe for the patient or for hospital staff. Delirium and agitation often occur together, but delirium may occur without agitation. Use of a validated tool, such as the Confusion Assessment Method for the ICU (CAM-ICU), to determine if the patient is experiencing delirium will assist in diagnosing and treating this condition.
Diagnostics
Patients suspected of having delirium should have electrolytes as well as renal and liver function tests and an arterial blood gas drawn to help determine the cause of the delirium. Causes of delirium are discussed in Table 13.1.
Intervention
Treatment of encephalopathy and delirium includes searching for and treating the underlying cause, providing a supportive environment, and using medications and nonpharmacological interventions to treat symptoms of delirium. Causes of delirium are outlined in Table 13.1. Pain medications and many cardiac medications may lead to delirium, especially in elderly patients. Medications, especially those newly administered, should be reviewed carefully to determine if any may be causing delirium. If an underlying cause for post-op encephalopathy or delirium cannot be found, it may be a consequence of surgery. Often, encephalopathy and delirium improve once a patient is transferred out of the ICU. While delirium is present, a supportive environment should be provided. Patients should be reassured and reoriented frequently. Patient safety should be maintained during this time. An excellent resource for management of delirium is a website sponsored by the Delirium and Cognitive Impairment Study Group at Vanderbilt University: www.icudelirium.org.
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