Standard Management of Cardiac Surgery Patients

Chapter 17 Standard Management of Cardiac Surgery Patients



Andrew McKee, David Sidebotham, Patrick A. Gladding


Many of the physiologic changes, potential problems, and objectives that occur following routine cardiac surgery are common to all patients and as such are suitable for protocol-based management. In this chapter the standard management of cardiac surgery patients is reviewed. To a certain extent the management strategies outlined here reflect our own institutional practice, which may differ from the practices at other hospitals. Furthermore, the responsibility for various aspects of patient management differs among countries and institutions. The guidelines serve to highlight the areas of patient care that are amenable to protocolized management; the actual details of the protocol and who performs a particular aspect of care are relatively unimportant. Some of the issues that arise following discharge to the ward are dealt with in this chapter, but the emphasis is on early care in the intensive care unit (ICU) following uneventful surgery. The management of postoperative variances, complications, and prolonged ICU care is not addressed in this chapter.



CLINICAL PATHWAYS


Over the past decade many units have introduced clinical pathways for adult cardiac (and thoracic) surgery patients. Clinical pathways are integrated management plans that provide time-specific goals for all aspects of a patient’s care during the entire hospital stay, including the ICU period.1 Deviations from the expected postoperative course are listed as variances. Important variances, for instance failure to be discharged from the ICU on postoperative day (POD) 1, may then be audited and used for the purposes of research and continuous quality improvement. Patients requiring prolonged ICU stay (>48 hours) are typically removed from the pathway.


Potential advantages of clinical pathways include: (1) selecting “best practice” methods; (2) avoiding omissions, variations, and duplications of tests and treatments; (3) providing a common “game plan” for all staff members; (4) providing data for continuous quality improvement; (5) decreasing nursing and physician documentation; (6) potentially reducing length of hospital stay and thereby minimizing costs. In some institutions, clinical pathways are recorded electronically, which has the advantage of improving the accuracy and efficiency of data collection. Despite the widespread use of clinical pathways in cardiac surgery, they have been subjected to minimal research. In one study, the introduction of a clinical pathway for coronary artery bypass graft (CABG) surgery was associated with a 9% reduction in length of hospital stay,2 but over the same time period, a similar reduction in length of stay was observed in comparison hospitals that did not use clinical pathways.



OVERVIEW OF PATIENT CARE


The goal, after uncomplicated cardiac surgery, is for a patient to be admitted to the ICU for fewer than 24 hours, with discharge to the ward or step-down unit occurring in sufficient time to allow the bed to be used by another patient on the following day. The expected time course for a patient is as follows:


• Admit to ICU; morning cases typically arrive in the middle of the day, afternoon cases in the late afternoon.

• Rewarm to 36.5°C within 3 hours of admission.

• Extubate within 6 hours of admission.

• Keep in ICU overnight, during which time any vasoactive drugs are weaned to a low level or discontinued completely.

• Remove chest drains, arterial line, and pulmonary artery catheter (PAC) on the morning of POD-1.

• Transfer to ward or step-down unit by midmorning or early afternoon of POD-1.


Admission to the ICU


Prior to the patient’s arrival, the operating room team should notify the ICU team of the patient’s progress and expected time of arrival in the ICU.



Arrival of the Patient


The majority of patients are transferred from the operating room to the ICU intubated and ventilated, with portable monitoring and battery-powered drug-infusion devices. On arrival in the ICU, the following events occur rapidly:


• The patient is connected to the ICU ventilator and the settings are confirmed.

• Monitoring is transferred and transducers are leveled and zeroed.

• Drains are connected to suction. The fluid level of each drain is recorded.

• Infusion pumps are plugged in and the drug doses are confirmed.

• The patient’s vital signs and the adequacy of ventilation are checked.

• The patient’s details are handed over from the operating room team to the ICU team.

At this time there is considerable activity at the bedside, and it is easy to become distracted from observing the patient’s vital signs. Problems such as hypoxemia, hypotension, and arrhythmias are easily missed. If monitoring is temporarily unavailable or there is doubt about its accuracy, continuous clinical assessment by inspecting for cyanosis, observation of the chest rising and falling, and palpation of a central pulse is mandatory.



Handover of the Patient’s Details


Handover of the patient’s details from the operating room team to the ICU team should cover the following issues:


• The patient’s preoperative history, medications, and drug allergies.

• Details of the operation.

• Details of all lines and tubes and any associated problems.

• The patient’s current status, including drug infusions, pacing, bleeding and coagulation status, and blood product usage.

• Any other relevant issues (e.g., difficulty with tracheal intubation, resetting of an internal pacemaker).


Initial Investigations


Blood samples for arterial blood gases, glucose, potassium, ionized calcium, and a complete blood count should be obtained shortly after arrival. If bleeding is a concern, an activated clotting time (ACT), thromboelastogram (TEG), and coagulation screen (prothrombin time, partial thromboplastin time, fibrinogen) should be sent. A supine portable chest radiograph should be obtained in all patients.



Initial Assessment and Treatment by the Medical Team


Following admission to the ICU, the medical team should review the patient, document the clinical findings, and formulate a management plan. The initial examination and treatment should focus on the following elements.



Cardiovascular System


The patient’s heart rate, rhythm, mean arterial pressure, and central venous pressure are reviewed. If a PAC is in situ, cardiac output, mixed venous oxygen saturation (SVO2), and pulmonary artery wedge pressure (PAWP) should be measured. Clinical assessment of cardiac output is unreliable during the early postoperative period.3


If the heart is being paced, the pacemaker settings should be confirmed; asynchronous pacing (DOO, VOO, AOO) should be converted to synchronous pacing (DDD, AAI, VVI), typically at a rate of 80 to 90/min (see Chapter 21). If an intraaortic balloon pump is in situ, its timing and augmentation should be confirmed, the insertion site inspected to ensure that there is no bleeding or hematoma formation, and the limb perfusion checked.


Hemodynamic goals vary depending on the patient’s history, the operation, and institutional practice (see Chapter 20); typical values for the early postoperative period are listed in Table 17-1. Hypovolemia and modest vasodilatation are common during the early postoperative period, and a fluid challenge may be required. The doses of any vasoactive drugs should be confirmed. Vasoactive and inotropic drugs may be titrated to the patient’s hemodynamic state (mean arterial pressure, cardiac output) or, in patients with impaired ventricular function, they may be maintained at a constant level for a set period (e.g., until extubation or overnight).


Table 17-1 Standard Hemodynamic Goals During the Early Postoperative Period


















MAP 65-90 mmHg
CVP 8-12 mmHg
PAWP (or PAD) 10-14 mmHg
Cardiac index >2.2-2.6 l/min/m2
SVO2 (or SSVCO2) >60%-70%

CVP, central venous pressure; MAP, mean arterial pressure; PAWP, pulmonary artery wedge pressure; SSVCO2, superior vena cava oxygen saturation; SVO2, mixed venous oxygen saturation; PAD, pulmonary artery diastolic pressure



Respiratory System


The adequacy of ventilation is assessed by: (1) auscultating the patient’s chest to ensure that air entry is equal and that the breath sounds are normal; (2) reviewing the oxygen saturation (SpO2) and blood gas results; and (3) checking the ventilator settings. The endotracheal tube should be inspected to ensure that it is properly secured and at an appropriate distance from the teeth and gums (21 to 23 cm for women, 22 to 24 cm for men). Changes in the initial ventilator settings are commonly required, depending on the blood gas results. The presence of coarse breath sounds or high airway pressures suggests the need for endotracheal suctioning. Discontinuation of mechanical ventilation can usually proceed according to standard protocol.



Bleeding and Fluids


All surgical sites should be inspected for bleeding and hematoma formation. If a radial artery graft has been used, the donor forearm should be elevated and the perfusion to the hand assessed. Chest drains should be inspected for blood and the presence of bubbling. A transfusion threshold should be determined. The results of any coagulation tests should be reviewed and a decision regarding the need for blood component therapy made. Maintenance and resuscitation fluids should be prescribed, usually according to protocol.



Renal System and Electrolytes


Following cardiopulmonary bypass (CPB), patients are typically polyuric. The absence of polyuria may indicate a blocked or kinked urinary catheter. If this is suspected, the catheter should be flushed with 50 ml of sterile water. Polyuria is not usual after off-pump coronary artery bypass (OPCAB) surgery. Red staining of the urine indicates either elevated free plasma hemoglobin or urinary tract bleeding, both of which are common in postoperative cardiac surgery patients. Coagulation tests and a measure of the plasma-free hemoglobin concentration should be obtained. Potassium and, possibly, magnesium supplementation should be prescribed.



Other


Pupil size and reactivity should be noted and the patient’s level of sedation documented. Core temperature should be measured, and the patient should be rewarmed to 36.5°C using a forced-air warming device, taking care not to cause hyperthermia (i.e., maximum ≤37°C). All lines and tubes should be inspected. Routine postoperative drugs should be prescribed.



Chest Radiograph


The chest radiograph should be reviewed to check the positions of all lines and tubes, to assess the presence of any pulmonary pathology (atelectasis, pulmonary edema, pneumothorax, fluid collection), and to rule out abnormalities of the cardiac silhouette indicative of mediastinal bleeding, pericardial fluid, or ventricular dysfunction.



Medical Rounds


The patient should be reviewed every 2 to 4 hours by the medical team, or more frequently if indicated. The treatment plan should be updated according to the patient’s progress. On the morning of POD-1, a multidisciplinary ward round should be performed and should include input from all members of the healthcare team: doctors, physician’s assistant, nurse, physical therapist, dietitian, and pharmacist. The suitability of the patient for discharge to the surgical ward should be assessed at that time.



Bedside Care


The bedside care of the patient is primarily the responsibility of the patient’s nurse. The nurse is responsible for monitoring and documenting the patient’s clinical condition, facilitating progress, and detecting and intervening in potential problems. In a well-run ICU with clear practice guidelines, the great majority of patient care is carried out by the bedside nurse according to protocol.


A detailed record of the patient’s clinical state is recorded in the 24-hour chart. Hemodynamic and respiratory status, fluid balance (including chest drainage), and drug infusions are recorded every half hour. Blood gases, potassium, and glucose are obtained every 2 hours initially while the patient is ventilated, and every 4 hours thereafter. If a PAC is in situ, cardiac index, SVO2, and PAWP are recorded every 2 hours, at least initially. The patient’s neurologic status (pupil size and reactivity, depth of sedation) is recorded every 2 to 4 hours. If a radial graft has been used or an intraaortic balloon pump is in situ, perfusion to the affected limb should be documented every 1 to 2 hours. Immobile patients should be turned every 4 to 6 hours, varying among supine and left and right lateral tilt positions to avoid the formation of pressure areas. However, for the many patients who are ventilated for only a few hours, this is not necessary. Prior to stopping sedation, a patient is usually sponge-washed to remove any dried blood or surgical antiseptic from the skin. Once the patient is extubated, pain and sedation scores and nausea are assessed on a regular basis (see Chapter 4).


At the start of each nursing shift, a detailed handover of the patient’s status and progress takes place, and a nursing care plan is formulated. Once per nursing shift, a multisystem assessment of the patient and associated devices is performed. This includes examining the patient, checking the ventilator settings and alarms, zeroing and leveling the transducers, checking all drug infusions, checking the monitors’ alarm settings, and checking that the suction tubing and drains are all connected and working correctly. For a patient who is paced, the pacing mode, thresholds, and sensitivities are assessed. The presence and function of emergency equipment, such as a manual resuscitator, oxygen tubing, oral airway, and mask, are confirmed.


On the morning following surgery, a 12-lead electrocardiogram (ECG) and a full set of blood tests (urea and creatinine, electrolytes, blood gas, hepatic function, CK-MB, troponin, and complete blood count) are obtained. Once the chest drains are removed, a repeat chest radiograph is performed.



MANAGEMENT OF SPECIFIC ISSUES



Drugs Given at Admission


Most units have a standard protocol for the drugs that are prescribed on admission. They may include electrolytes, sedatives and analgesics, antiemetics, antipla telet drugs, and prophylaxis for atrial fibrillation. Additional medications are also indicated for specific cardiac procedures, such as CABG surgery and valve surgery. The routine drugs used at our institution are shown in Table 17-2. Individual practice varies widely.


Table 17-2 Examples of Routine Drugs










































Sedation and Analgesia  
Propofol 100-300 mg/hr titrated to effect
Morphine IV: 1-2 mg as required; PO: 10-20 mg of a short-acting formulation as required + 10-20 mg of a long-acting formulation twice daily for 3 days
Acetaminophen 1 g PO or PR 6 hourly
Antiemetics  
Ondansetron 4 mg 6 hourly PO or IV as required
Prochlorperazine 12.5-25 mg 8 hourly PO or PR as required
Dexamethasone 8 mg daily IV as required
Atrial Fibrillation Prophylaxis  
Amiodarone 400 mg PO 3 times daily for 2 days beginning on the first postoperative day; thereafter 200 mg twice daily for 1 week
Other Drugs  
Potassium chloride 10-20 mmol IV slowly to maintain K+ 4.5-5 mmol/l
Furosemide 20-40 mg IV daily starting on POD-1 and continuing until back to preoperative weight

Note: these are the drugs used at the authors’ institution. Additional drugs are given for specific cardiac operations.


IV, intravenous; PO, per os; POD, postoperative day; PR, per rectum.



Electrolytes


Following CPB, renal potassium losses are typically high, which can cause hypokalemia and precipitate arrhythmias. Aggressive potassium supplementation is commonly required in the first few hours following surgery, aiming for a serum concentration of 4.5 to 5 mmol/l. Hypocalcemia and hypomagnesemia are also common during the early postoperative period. Calcium typically normalizes over a period of hours without the need for supplementation. Magnesium supplementation should be considered in patients with marked hypomagnesemia (>0.8 mmol/l), preoperative diuretic use, or an unstable rhythm. Magnesium sulfate may form part of routine prophylaxis against atrial fibrillation.



Analgesic Medications


In intubated patients, analgesia may be provided by intermittent intravenous administration of an opioid such as morphine combined with intravenous or rectal acetaminophen (see Chapter 4). Once the patient is extubated and awake, intravenous opioid therapy may be given by means of a patient-controlled analgesia system in combination with oral or rectal acetaminophen. Nonsteroidal antiinflammatory drugs may be used in patients who are without contraindications but are best avoided until postoperative renal function is known.



Drugs for Patients After CABG Surgery


Aspirin is administered following CABG surgery once bleeding has settled (see Chapter 9

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Jun 5, 2016 | Posted by in CARDIOLOGY | Comments Off on Standard Management of Cardiac Surgery Patients

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