Mason, Virginia Fidrocki PhD(c), RN, CS; Miller, Kathleen H. EdD, RN, CS-ACNP
Cardiovascular conditions such as coronary heart disease and valvular disease are major causes of morbidity and mortality in the United States and the leading cause of death in Americans age 65 years and older. 1 In 1996, approximately 151 billion dollars was spent on patients with cardiovascular diseases. 2 Treatments include diet adjustment, implementing an exercise regimen, and pharmacological management; for patients who can’t be treated conservatively, cardiac surgery is an option. More than 366,000 coronary artery bypass surgeries (CABS) are performed annually in the U.S. Of those patients who undergo CABS, approximately 57% are over age 65, with 20% more men than women. 2 Each year, in the U.S., approximately 78,000 valvular surgeries are performed to replace or repair heart valves. People age 65 years or older comprise more than 60% of these valvular procedures, with men outnumbering women two to one. 2 As of 1997, mean hospital costs for these types of heart surgery have been estimated at $21,000. 3 For patients experiencing complications after cardiac surgery, increased length of stay in the critical care unit contributes to increased costs. In addition, such health problems can result in a higher mortality rate for these patients or an impaired quality of life after discharge from the hospital. Therefore, knowledge of recovery patterns is beneficial. Nurses will be better able to distinguish those postoperative cardiac surgical patients who require intensive nursing interventions and those who require less. 4–6
Cardiac arrhythmias and respiratory insufficiency are common postoperative complications in cardiac surgical patients. 7,8 Atrial arrhythmias such as atrial fibrillation and atrial flutter occur 25% to 50% of the time following cardiac surgery, usually on the second or third postoperative day. 7,9–11 Respiratory insufficiency, a common postoperative complication of CABS, may result in prolonged intubation. These complications can require pharmacologic treatment (such as antiarrhythmics) or electrical treatment (synchronized cardioversion, for example) or both, and could lead to readmittance to the critical care unit.
Cardiac arrhythmia. Predictors of atrial arrhythmias, a factor that promotes patient time spent in the critical care unit postoperatively, can include advanced age, longer P-wave duration (which indicates atrial enlargement), a history of hypertension, and the presence of right coronary artery disease (defined as a greater than 70% narrowing of the lumen’s diameter in the proximal or middle segment of the right coronary artery as indicated by cardiac catheterization.) 9–11 Despite these predictors, current research has yet to successfully establish preventive interventions. For example, in a study of 300 patients involving the random use of postoperative iv amiodarone, the Amiodarone Reduction in Coronary Heart (ARCH) Trial reported a 26% relative risk reduction in the occurrence of atrial fibrillation postoperatively; however, they also found that it did not significantly alter length of hospital stay. 10 Edward Gerstenfeld and colleagues’ attempt at right atrial and biatrial temporary pacing after CABS also did not significantly lower the incidence of postoperative atrial arrhythmias. 11 Although oral digoxin seems to control the rapid ventricular rates seen when atrial fibrillation occurs, its preoperative and postoperative use has been conflicting in its success rate in preventing postoperative atrial fibrillation. 9
Respiratory insufficiency. Respiratory insufficiency delays the transfer of high-risk patients out of the critical care unit because of their need for mechanical ventilation or aggressive pulmonary therapies. Respiratory insufficiency (the inability to support adequate ventilation and maintain airway clearance without an endotracheal tube) and mechanical ventilation occur frequently after cardiothoracic surgery. Cardiothoracic surgery, anesthesia, and the use of the cardiopulmonary bypass machine all contribute to potential respiratory problems such as atelectasis, pneumonia, or infections. Research has shown that factors such as advanced age, female gender, presence of unstable angina, hemodynamic instability, abnormal temperatures, renal insufficiency, need for intra-aortic balloon pump (IABP) support, and longer time on cardiopulmonary bypass affected time to extubation. 12 The presence of preexisting comorbidities, incidence of unstable angina, or myocardial infarction within one week of surgery did not have a significant effect on the extubation time. 12
Other complications. Cardiac surgery performed “on pump” or with extracorporeal circulation has the potential for developing a systemic inflammatory response as well as adverse changes in hematologic values and cognitive function. 13 Revascularization accomplished by the “off-pump” or beating heart method of coronary artery bypass potentially avoids these problems. 13 Rather than stopping the heart, as is done during on-pump surgery, off-pump coronary artery bypass (OPCAB) surgery involves utilizing a small stabilizing device to allow the surgeon to work on a small area of the heart while it continues to beat at a normal rate. 14 Repositioning of the heart within the chest allows for the performance of more than just anterior bypass grafts; posterior grafts are also possible. 14 OPCAB has been associated with lower incidence of postoperative stroke or cerebral problems, 6,12–14 and candidates for open-heart surgery can include those with respiratory problems who were previously considered poor surgical risks because of their inability to wean off the ventilator after prolonged use of cardiopulmonary bypass. 14 However, OPCAB opens the possibility of other complications such as poor sternal wound healing, for example, in patients with chronic obstructive pulmonary disease who are on steroids. 14
Nurses who care for patients after cardiac surgery can promote optimal outcomes, early transfers, and help their patients return to their homes as soon, and as safely, as possible. Ideally, strategies to enhance postoperative recovery need to be initiated preoperatively. Meeting patients prior to surgery allows for preoperative instruction and patient–family assessment to take place. Including the patients and their families in discussions of postoperative expectations encourages them to participate more in their care. In general, developing care plans that include knowledge of risk classification systems, early transfer candidates, and postoperative interventions reconciles patient care satisfaction and hospital demands for more cost-effective measures.
Factors contributing to comorbidities. High-risk classification factors include: advanced age (over 65), female gender, left ventricular dysfunction, presence of diabetes, incidence of reoperation, need for emergency (rather than elective) surgery, and mortality risks. By considering these factors, the nurse can predict possible postoperative complications and length of ICU or hospital stay following open-heart surgery. 15–18 Several risk classification systems have been developed, such as the Parsonnet Score or the Thoracic Surgical Risk Index, both of which predict outcomes after cardiac surgery including morbidity, mortality, and length of stay in the critical care unit. 15,18 The Parsonnet scoring system, a bedside estimation of risk for cardiac surgery, is the most widely used risk classification system in the United States. 15,16 The Society of Thoracic Surgeons (STS) established a national cardiac database in 1989 to be used by its members to analyze and report risk-adjusted outcomes for cardiac surgery patients. The database has been updated in the past two years to improve the performance of the algorithm. For example, a risk index developed by Jack Tu, a physician and researcher, indicates that age, gender, left ventricular function, type of surgery, and urgency of surgery were all significant independent predictors of length of ICU stay after cardiac surgery. 18 This means that the presence of one of those factors alone is enough to determine which patients stay longer in critical care units. Other researchers cite not only age and gender, but also reoperation, undernutrition, prolonged mechanical ventilation, length of bypass time, and higher clinical risk scores as predictive of increased mortality after cardiac surgery. 15
Early transfer candidates. Early transfer from the critical care unit can decrease hospital costs and improve patient satisfaction. The patient’s exposure to disconcerting elements like noise, lights, voices, and procedures often associated with a critical care unit will be minimized. Early transfer also promotes early ambulation, which leads to faster recovery. Factors that promote early transfer from critical care (less than 12 hours after surgery) to the telemetry unit are early extubation, age (under 60 years old), and male gender. 3,17 Unlike men, women have more preoperative risk factors including multiple comorbidities, emergency surgery, postoperative complications, and a higher incidence of mortality following CABS. 17,19,20 There are several reasons for these differences in outcomes for men and women. Women’s higher functional class leads to their increased risk of morbidity and mortality after cardiac surgery. 21 In the New York Heart Association’s functional classification of heart disease, this indicates the likely occurrence of fatigue, palpitations, dyspnea, or anginal pain in relation to the patient’s activity level. Additionally, because women have smaller blood vessels than men, operational procedures to allow adequate blood flow through bypass grafts become more difficult technically, and the surgeon may not be able to revascularize specific coronary arteries.
Postoperative strategies. The two most commonly identified postoperative complications are cardiac arrhythmias and respiratory insufficiency. 7,17 Current nursing strategies involve vigilant monitoring for early detection of premature arrhythmias leading to more complex or lethal arrhythmias. Nurses also need to monitor fluid and electrolyte balance and oxygenation saturation. If arrhythmia occurs, the patient requires immediate attention. For patients with respiratory complications, starting aggressive pulmonary toileting prior to surgery and following a uniform method of weaning from the mechanical ventilator can help decrease intubation time. Postoperative incentive spirometry needs to be used every hour while the patient is awake. Expanding and clearing the airways of excessive mucus is the key to improving arterial blood gas measurements and oxygen saturation as measured by pulse oximetry.
Early extubation in CABS is influenced by a number of variables including type of surgery—on-or off-pump, “mid cab,” or sternal approach—and the type of anesthesia, sedation, or pain medication administered. 12,13 The use of inhalational anesthetics versus the more traditional opioid, reversal of muscle relaxants, and rewarming in the operating room all contribute to earlier extubation, and earlier discharge. 12 Early extubation in the operating room or within six hours of surgery, also called fast track recovery programs, use anesthetics such as propofol and are associated with lower incidences of pneumonia and renal dysfunction, improved respiratory function and dynamics, and earlier return of cough reflexes as well as increased patient satisfaction. 6,12–14 Age also plays a factor in early extubation; one study reported that patients under age 50 were more likely to be extubated within four hours of surgery than their older counterparts. 12
Nurses can teach patients to be proactive in their own recovery after cardiac surgery by showing them how to turn properly from side to side, cough, and improve their respiratory status by breathing deeply. Sitting the patient on the side of the bed with his feet dangling allows for fuller expansion of the lungs and proper drainage of blood, and minimizes postoperative respiratory problems such as pneumonia and atelectasis. Proper positioning also promotes early extubation from the mechanical ventilator. Early ambulation promotes speedy recovery and reduces potential muscle wasting from prolonged bed rest or inactivity.
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© 2001 Lippincott Williams & Wilkins, Inc.