Postoperative care of the cardiac surgery patient is challenging in that changes can occur rapidly. The preoperative condition of the patient as well as intraoperative events should be considered in postoperative care. It is essential for the nurse to anticipate the possible complications so that appropriate interventions are initiated in a timely manner in order to ensure a positive outcome for the patient.
There is a flurry of activity as the patient enters the recovery room/ICU and the admitting nurse connects the patient and the invasive lines to the monitoring equipment while another staff member connects drainage devices appropriately and draws admission blood work. The operating room nurse and the anesthesiologist report the patient’s condition to the receiving nurse.
Postoperative Pulmonary Management
Pulmonary dysfunction and hypoxemia may occur in 30% to 60% of patients after CABG.10 Patient history and intraoperative factors must be considered in the postoperative pulmonary management. A history of smoking, obstructive pulmonary disease, steroid use, gastroesophageal reflux disease, heart failure, and poor nutrition may increase postoperative pulmonary complications.11
Although there are some variations to this protocol, most patients will be intubated and mechanically ventilated upon arrival in the recovery room. Desired outcomes include adequate oxygenation and ventilation while the patient is intubated. Early extubation isalso a desired outcome as long as the patient is hemodynamically and neurologically stable. There is potential for an increase in postoperative complications when patients are intubated longer than 24 hours. The length of hospital stay may also increase with longer intubation times.12 The current trend is to extubate patients within the first 12 hours after surgery. On occasion, patients may be extubated in the operating room. Routine postoperative care to promote oxygenation and ventilation involves prevention and treatment of atelectasis and pulmonary infection as well as maintenance of effective gas exchange and breathing patterns.
There are several factors during heart surgery that increase the potential for pulmonary complications postoperatively. The length of the surgery and resultant increase in the amount of needed anesthetic agents, the amount of fluids administered during the intraoperative period, and prolonged time in the supine position increase the potential for pulmonary complications. Atelectasis can be related to cardiopulmonary bypass, surfactant inhibition, and stimulation of the inflammatory response.9 Atelectasis, as well as the inflammatory mediators, inhibits diffusion of oxygen and carbon dioxide across the alveolar capillary membrane and impairs effective gas exchange.
Prolonged pump time causes fluid shifts, potentially increasing the amount of fluid in the pulmonary tissue, thus increasing the possibility of pulmonary complications. Pain caused from the sternotomy can impair breathing patterns. Some patients shiver after heart surgery and this response may lead to an increase in the carbon dioxide level or lead to lactic acidosis. Shivering may increase the body’s oxygen consumption, therefore, oxygen levels should be monitored and adjusted accordingly. Shivering may be the result of the body compensating for the surgically induced hypothermia or a reaction to anesthetic agents. Shivering is usually managed by administration of sedation and neuromuscular blocking agents while the patient is being mechanically ventilated.
Postoperative management includes accurate and frequent physical assessment, arterial blood gas analysis, continuous pulse oximetry, pulmonary care (including suctioning while the patient is intubated and coughing and incentive spirometry after extubation), early mobilization, and control of pain and shivering. Most protocols require a chest x-ray after heart surgery to determine placement of the endotracheal tube, thermodilution catheter, and nasogastric tube as well as information about the width of the mediastinum, amount of atelectasis, presence of hemothorax or pneumothorax, and size of the heart.
Pain control is usually achieved with intravenous narcotics while the patient is intubated. Oral and/or intravenous narcotics may be used after extubation. The nurse must balance the need for pain control without respiratory depression with the patient’s need to have his/her pain minimized to allow an effective cough.
The nurse must assess the patient for readiness for early extubation. Extubation should be considered when the patient is arousable, able to follow commands, hemodynamically stable, and initiating spontaneous ventilations without excessive respiratory effort. Typical intensive care protocols for the cardiac surgery patient include preprinted orders that facilitate the weaning process. As the patient is being weaned from the ventilator, ventilatory support is gradually withdrawn and the patient must sustain spontaneous ventilations. Physical assessment of effective ventilation, and laboratory analysis of arterial blood gases and specific ventilatory parameters must be completed prior to extubation. Protocols may vary, but some standards require a PO2 > 80 mm Hg on a FIO2 of 0.40 or less, a PCO2 less than 45 mm Hg, a pH between 7.35 and 7.45, and an oxygen saturation (SaO2) >92%.
Ventilatory parameters include a maximum inspiratory pressure of at least -20, a tidal volume of at least 5 mL/kg body weight, and aminute volume of at least 5 liters per minute (see Table 2). During the weaning process, the nurse should assess the patient for an increase in respiratory and/or heart rates, use of accessory muscles, fatigue, and color changes because these findings may indicate the patient is not ready for extubation. An increase in pulmonary artery pressures can indicate an increase in PCO2 and give the nurse an early indication prior to arterial blood gas analysis that the patient is not ready for extubation. Early extubation is desirable but if parameters are not met and/or the patient is hemodynamically unstable, there may be detrimental effects of early extubation.
Postoperative Management of Hemodynamics
Movement of the patient from the operating room to the recovery room/ICU can create hemodynamic instability, and thus, reconnection to the monitoring equipment in a timely manner is of the essence. A cuff BP is usually taken to provide correlation of the BP obtained from the arterial line.
Intraoperative myocardial ischemia is a potential cause of low cardiac output (CO) during the immediate postoperative period. The nurse must continually assess the patient for cardiac dysfunction and hemodynamic instability. The receiving nurse must intensively monitor the interrelationship between heart rhythm and rate, preload, afterload, contractility, and myocardial compliance to achieve this outcome. Preload is determined by the volume of blood returning to the right atrium as well as by myocardial compliance. Preload is a measurement of end diastolic pressure. Afterload is the force the left ventricle must overcome to eject blood during systole. It is determined, in part, by myocardial contractility and systemic vascular resistance. Myocardial contractility refers to the force generated by the heart during systole.13 Myocardial compliance is the ease with which the heart distends during diastole.
Blood pressure must be maintained within ordered parameters to provide tissue perfusion and prevent disruption of the surgical anastomoses. BP is CO multiplied by systemic vascular resistance (SVR). The nurse must monitor the volume in the system, which is reflected by the right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP).
If the BP is too low, there is either too little volume (preload), a decrease in contractility, or the SVR is too low (the patient’s blood vessels are dilated). If the BP, CO, and RAP/PCWP are all low, the patient probably needs volume (see Table 3). Volume is generally replaced as needed with a colloid such as hetastarch unless the hematocrit is low and then volume may be replaced with packed red blood cells. If the BP and CO are low but the PCWP is high, the patient may be experiencing decreased contractility and inotropic support may be instituted with an agent such as dopamine or dobutamine. If the BP is low and the CO is adequate or elevated, the systemic vascular resistance may be low and the patient may need a constrictive agent such as phenylephrine (see Table 3). Low BP can be temporarily increased by turning off positive end expiratory pressure (to decrease intrathoracic pressure and augment preload) and by position changes.
The patient should be put in the supine position with legs elevated to allow the BP to increase until the cause of the low BP can be determined and corrective measures are taken. Although not universally utilized, some institutions continue to place patients in the Trendelenburg position. The Trendelenburg position can offer symptomatic relief from low BP, especially in the early postoperative phase, by shifting volume from the legs to the chest and increasing preload. The positive changes identified with Trendelenburg positioning seemed to provide only temporary improvement in the clinical picture.15 If the BP becomes too high, especially in the early postoperative period, the surgical anastomoses may become disrupted, which could cause significant intrathoracic bleeding, hemodynamic instability, poor tissue perfusion, and necessitate a return to the operating room. It is important for the nurse to carefully monitor the patient for high BP and quickly intervene per institution protocol. Nitroprusside, a vasodilator, is often administered to lower the BP to the ordered parameter. Nitroglycerine, a nitrate, may also be used to cause vasodilation and lower the BP (see Table 3).
These medications should be started slowly so patient response can be evaluated. The patient must be monitored closely as the BP may drop as the patient’s body temperature increases. The nurse must rewarm the patient after surgery if hypothermia persists. The negative effects of hypothermia include depression of the myocardium, ventricular dysrhythmias, vasoconstriction, and depression of clotting factors (increasing the risk of bleeding postoperatively).13 Many surgeons attempt to achieve normothermia because of the deleterious effects of hypothermia. If the patient is hypothermic, rewarming may be accomplished by the use of warm blankets, warm humidified oxygen, convective air mattresses, and other individual institutional approaches.
Vasoconstriction induced by hypothermia may increase BP. Because of the potential for issues with graft anastomoses and the importance of maintaining BP within the reference range, a vasodilator may be needed while the patient is rewarming. As normothermia is achieved, if the patient’s systemic vascular resistance decreases significantly, additional intravenous fluids may need to be administered. The nurse should carefully monitor the pulmonary artery pressures and the CO as well as the BP when interventions are instituted to assess the effect. Some references suggest that hemodynamic parameters be rechecked every 30 to 60 minutes after each intervention during the early postoperative period.
It is important to maintain effective CO after open heart surgery to provide adequate tissue perfusion. Cardiac index can be decreased if the heart rate increases to the point of compromised ventricular filling with a resultant decrease in the stroke volume. Cardiac index (CI) can also be decreased with bradycardia. Cardiac index can be decreased if the SVR (afterload) is elevated, making it more difficult for the ventricles to eject the end diastolic volume of blood. One factor that can cause an elevation in afterload is the surgically induced hypothermia leading to vasoconstriction. A decrease in myocardial contractility or circulating volume can further compromise CI. If the patient is hypothermic, this may result in myocardial depression, thus compromising contractility.13 After the cause of the decrease in theCO/CI is determined, management can be initiated. If the CO/CI is low and the PCWP is high, inotropic support is probably needed. If the CO/CI is low and the PCWP is low, volume is likely needed (see Table 3). If the SVR is elevated in the early postoperative period, it may be due to hypothermia or the patient may need volume.
It is easy to rely only on the values obtained with hemodynamic monitoring when assessing a patient. The nurse must also use effective clinical assessment skills. Peripheral perfusion assessment data are vitally important in the evaluation of effective CO.16 The nurse should regularly perform neurovascular assessments of the lower extremities to provide information about the effectiveness of CO.
Dysrhythmias are common after CABG surgery. Constant assessment of the patient, as well as continuously monitoring the cardiac rate and rhythm, is imperative. Ventricular dysrhythmias are more common in the early postoperative period and supraventricular dysrhythmias are more likely 24 hours to 5 days postoperatively.17 The incidence of atrial fibrillation ranges from 10% to 65% depending on many factors including patient history, preoperative medications, and type of surgery.18 Hypothermia, inhaled anesthetics, electrolyte disturbances (ie, hypocalcemia, hypercalcemia, hypomagnesium, and hypokalemia), metabolic disturbances (such as acidosis), manual manipulation of the heart, and myocardial ischemia may be factors in postoperative dysrhythmias.
Dysrhythmias can also be the result of an increase in catecholamine levels secondary to pain, anxiety, and inadequate sedation. Management depends on the type of dysrhythmia and the patient’s clinical response. The nurse must treat the patient and not only the monitor. Effectiveness of BP and CO should be considered when evaluating dysrhythmias. Often, cardiac surgeons place epicardial wires on the atrium and/or the ventricle during the operation. Temporary pacing can be instituted to override a slow intrinsic rhythm so CI and BP can be maintained. Atropine may be given to increase the heart rate in the absence of epicardial pacing wires. Tachydysrhythmias are usually controlled pharmacologically. The specific medication utilized will depend on hospital protocols and physician preference. The critical care nurse should utilize standing orders in the institution as well as current advanced cardiac life support protocols. Postoperative Management of Bleeding
The postoperative period may be complicated by excessive bleeding. Many factors should be considered when assessing the patient’s potential for bleeding. Patients who were on anticoagulants and antiplatelet agents (including glycoprotein IIb/IIIa receptor antagonists such as abciximab) prior to surgery are at an increased risk of postoperative bleeding.19 The aorta and the atrium are cannulated during surgery. The grafts have proximal and distal anastomosis sites. Other potential sites for bleeding include the internal mammary site, the chest wall, and chest tube sites.
Induced hypothermia, the use of the CPB machine, and the administration of heparin for anticoagulation can all contribute to postoperative bleeding. The nurse should be aware that heparin can be stored in adipose tissue and some patients may have an increase in bleeding 4 hours postoperatively depending on the body’s adipose composition. Some surgeons utilize an intravenous infusion of aprotinin intraoperatively to minimize the risk of postoperative bleeding. This drug is a protease inhibitor that inhibits fibrinolysis.20 Aprotinin may also have some anti-inflammatory effects and therefore be beneficial to the patient after CABG.21
The nurse should monitor the patient for signs of bleeding from the chest tubes and the surgical sites as well as clinical signs of hypovolemia related to blood loss. Hemoglobin and hematocrit should be monitored at regular intervals during the postoperative period according to institution protocol. Sometimes the surgeon orders serial coagulation profiles for a patient at risk for bleeding. If bleeding is an issue, drugs such as protamine sulfate (to reverse the effects of heparin) or antifibrinolytic agents such as aminocaproic acid or desmopressin (DDAVP) may be ordered.22 Blood products such as fresh frozen plasma and platelets may also be ordered.
When bleeding occurs there is potential for the blood to accumulate in the pericardium, and therefore, the nurse must be cognizant of the potential for cardiac tamponade. The clinical manifestations of cardiac tamponade include lack of chest tube drainage, decreased BP, narrowed pulse pressure, increased heart rate, jugular venous distention, elevated central venous pressure, and muffled heart sounds. 13 Emergency reoperation would be required.
Postoperative Neurologic Management
Patients who require coronary artery bypass surgery are at an increased risk for neurologic complications. Stroke can be caused by hypoperfusion or an embolic event during or after surgery. Manipulation of the aorta has been implicated in embolic events.23 Other risk factors for stroke may include age, previous stroke, carotid bruits, and hypertension.24 The incidence of stroke is approximately 2.5%.23 The nurse should be particularly astute to neurologic assessment in the postoperative period. When the patient is admitted to the intensive care unit, he/she will likely be intubated and unconscious. The effects of the neuromuscular blocking agents will be apparent. Pupils should be assessed initially, however, normal size and reactivity may not return until agents utilized intraoperatively have been metabolized. Over the first few hours after surgery, the results of the neurologic assessment should improve gradually. By the time the patient is ready for extubation, he/she should follow commands and have equal movement and strength of the extremities with neurologic function approaching the patient’s normal.
It is difficult for significant others during this time because waiting during the awakening process can be anxiety provoking. Patients and significant others are informed prior to surgery of the risk for stroke and want that to be definitively ruled out as soon as the patient returns to the intensive care unit. The nurse should provide needed comfort but not give false hope, as the neurologic status cannot be completely assessed until the patient is fully awake and extubated. At that time, the patient should be assessed for orientation to person, place, time, and circumstance. A motor and sensory assessment should also be performed. A positive result is a good indication that an intraoperative stroke can be ruled out. Neurologic assessments must continue because the risk of stroke does not end with the operation.24 Postoperative Renal Management
There is a potential for renal dysfunction in the postoperative cardiac surgery patient. One reference suggests that the incidence is approximately 8%.1 Renal insufficiency may be related to advanced age, hypertension, diabetes, decreased function of the left ventricle, and length of time on the CPB.25 One indicator of effective CO is adequate renal perfusion as evidenced by urinary output of at least 0.5 mL/kg/h. The nurse must monitor the urinary output at least hourly during the early postoperative period. The urine should be assessed for color and characteristics as well as amount.
Diuresis is likely in the postoperative period when renal function is adequate, as the fluids mobilize from the interstitial to the intravascular space. The patient’s potassium level should be monitored at least every 4 to 6 hours for the first 24 hours, as potassium is lost with diuresis. Intravenous potassium replacement should be administered to keep the serum potassium levels within normal limits. The patient should be astutely monitored for cardiac dysrhythmias if the serum potassium level is abnormal. Other laboratory values that should be monitored at least daily are the blood urea nitrogen and serum creatinine. Postoperative Gastrointestinal Management
Gastrointestinal complications range from 0.12% to 2%.26 Complications include peptic ulcer disease, perforated ulcer, pancreatitis, acute cholecystitis, bowel ischemia, diverticulitis, and liver dysfunction. Some risk factors for gastrointestinal dysfunction include age over 70, a history of gastrointestinal disease, a history of alcohol misuse, cigarette smoking, heart valve surgery, emergent operation, prolonged CPB, postoperative hemorrhage, use of vasopressors, and low postoperative CO.26 If the gastroepiploic artery is used as a conduit for bypass, this may also increase the risk of gastrointestinal dysfunction. Anesthetic agents, analgesics, and hypoperfusion of the gut during surgery can also contribute to gastrointestinal dysfunction. The nurse should monitor the patient for bowel sounds, abdominal distention, and nausea and vomiting.
The intubated patient will have a nasogastric tube to low intermittent suction or Salem sump to continuous suction. Placement and patency should be assessed as well as amount, color, and characteristics of the drainage. Prior to extubation, if bowel sounds are present, the nasogastric tube will be discontinued and the nurse should continue to assess the patient for potential gastrointestinal disturbances. The nurse should administer antiemetic agents as ordered if the patient is nauseated. The comfort of the patient as well as the sterility of the sternal dressing must be maintained. Some surgeons order a histamine blocker to minimize acid secretion until normal dietary patterns are resumed. When the nasogastric tube is removed, the patient will be started on a clear liquid diet and this can be advanced as tolerated by the patient. Postoperative Pain Management
Dependent upon surgical approach, the patient may have a median sternotomy incision, leg incision(s), and/or a radial incision. Manipulation of the chest cavity, use of retractors during surgery, and electrocautery may all contribute to postoperative pain.27 In addition, positioning on the operating room table and length of time of the surgery may also be factors in pain experienced postoperatively.
Poorly controlled pain can stimulate the sympathetic nervous system and lead to cardiovascular consequences. The heart rate and BP can increase and the blood vessels can constrict, causing an increase in the cardiac workload and myocardial oxygen demand.27 Effective pain control is essential for patient comfort, hemodynamic stability, and prevention of pulmonary complications. Nurses must individualize pain assessment and control for each patient as responses vary among individuals.27 Opioid analgesics, positioning, mobilization, distraction, and relaxation techniques are among some of the methods of pain control. Keeping serum levels of opioid analgesics in the therapeutic range is beneficial. Nonsteroidal anti-inflammatory agents may be used in conjunction with opioid agents to control pain and minimize the amount of narcotic needed.
Ketorolac is a nonsteroidal anti-inflammatory agent that can be administered intravenously in the early postoperative period while the patient is still intubated. The nurse must monitor renal status of patients taking ketorolac, and the drug may be discontinued if the serum creatinine is elevated. The patient is at an increased risk of gastrointestinal bleeding when a nonsteroidal anti-inflammatory agent is used. Pulmonary care is more effective for the patient when pain is effectively managed. Teaching the patient to splint the incision when coughing and moving improves pain control.
The nurse should evaluate the effectiveness of pain management interventions regularly. Significant others are often concerned about the postoperative pain experienced by the patient. Explanations about interventions utilized and outcomes achieved can decrease anxiety. Another source of pain for the patient after CABG is the removal of the chest tubes. This usually occurs 24 to 48 hours postoperatively when the amount and characteristics of chest tube drainage meet ordered parameters as long as there is no air leak noted in the water seal chamber. Pain medication should be administered prior to removal of chest tubes per institution protocol to minimize the trauma of the procedure. Additional Postoperative Management
The incidence of infection of sternal and leg incisions after cardiac surgery is less than 3%.13 Risk factors for infection include diabetes, malnutrition, chronic diseases, and patients requiring emergent surgery or prolonged surgery. Assessment for, and prevention of, infection is part of the nurse’s role in the postoperative period. The patient should be assessed for local and systemic signs of infection. Postoperative antibiotics may be ordered. Dressings should be removed and incision care should be completed according to institution protocols. Control of blood glucose level may help with prevention of infection. It is desirable to control blood glucose levels of greater than 150 mg/dL with a continuous intravenous infusion of insulin versus intermittent subcutaneous insulin injections. This practice is thought to be helpful in the prevention of deep sternal wound infection.
Some surgeons order corticosteroids postoperatively. When used, these drugs are intended to minimize the potential risks of inflammation after heart surgery. Patients should be monitored for suppression of the immune system, as this can be an adverse effect of corticosteroid administration. Patients need to be taught how to slowly discontinue the medication after discharge per physician orders. The other potential effect of corticosteroid administration is an elevation in serum glucose levels. A sliding scale insulin order may be needed to maintain blood glucose levels within normal limits while the patient is in the hospital.
The nurse must intensively care for the patient in the early postoperative period. This intensive monitoring and postoperative discomfort can interfere with the patient’s need for sleep. There is a potential for sleep disturbance as the patient is recovering from CABG. Lack of sleep may negatively affect postoperative outcomes.28 Organization of needed care and provision of time for uninterrupted sleep cycles is important for effective outcomes. Some of the postoperative confusion experienced by patients may be minimized and positive outcomes maximized when time for sleep is provided. Hospital routines and too many visits by well-meaning significant others may add to the sleep deprivation problem. Significant others should be able to spend time with the patient, but it is the role of the intensive care nurse to balance the need for visitation with the need for rest and sleep.
It can be frightening for significant others to visit the patient during the early postoperative period because of the monitoring equipment and appearance of their loved one. Explanations regarding the equipment and physical appearance may be helpful. Often significant others need to overcome fear of touching the patient postoperatively and receive reassurance from the professional nurse that no harm will come from the touch.
A compassionate, knowledgeable, and skilled nurse caring for the patient after open heart surgery is an asset in the achievement of positive outcomes for the patient and his/her significant others. The care of the CABG patient is intense, complex, and rewarding. The patient is admitted to the intensive care unit unconscious, intubated, and completely dependent on advanced technology as well as the expert care of the health team. Typically 24 to 48 hours after the surgery, the invasive lines have been discontinued, the patient no longer needs to be mechanically ventilated, organ system function is returning to normal, and the patient is now ready to work toward increasing independence. Cardiac surgery is not the cure for coronary artery disease. It gives the patient the opportunity to make needed lifestyle adjustments and achieve the highest degree of health possible. Nurses are a part of the team that makes this return to health a possibility for the patient.
Student nurse journey. (n.d.). Retrieved from http://www.snjourney.com/ClinicalInfo/Systems/Cardiac/CABGCarePlan.htm Martin, C., & Turkelson, S. (2006). Nursing care of patient undergoing coronary artery bypass grafting. Retrieved from http://www.nursingcenter.com/lnc/journalarticle?Article_ID=638956