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
S_VO₂ (or S_SVCO₂)	>60%-70%

CVP, central venous pressure; MAP, mean arterial pressure; PAWP, pulmonary artery wedge pressure; S_SVCO₂, superior vena cava oxygen saturation; S_VO₂, 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 (S_pO₂) 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, S_VO₂, 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). Some surgeons also prescribe clopidogrel following OPCAB surgery. Intravenous nitroglycerin or a calcium channel blocker may be administered to help prevent spasm in coronary grafts. If a radial graft has been used, an oral calcium channel blocker may be commenced on POD-1. Many surgeons also routinely prescribe their patients β blockers and statins following CABG surgery, commencing on POD-1.

Drugs for Patients After Valve Surgery

After implantation of a mechanical valve or a mitral tissue valve, warfarin is commenced on the evening of POD-1 or −2 (see Chapter 10). A heparin infusion may also be used, beginning once bleeding has settled and continuing until warfarin has achieved therapeutic anticoagulation in the patient. For uncomplicated tissue valves in the aortic position, aspirin may be used as the sole anticoagulant, although a 6-week course of warfarin may be preferable.

Prophylaxis for Atrial Fibrillation

Many units administer routine drug prophylaxis against atrial fibrillation, most commonly involving combinations of a β blocker, amiodarone, and magnesium (see Chapter 21).

Insulin

Hyperglycemia is common following cardiac surgery and is associated with adverse outcomes. An intravenous sliding-scale insulin infusion is indicated for all diabetic patients (see Chapter 36). For nondiabetic patients, it is reasonable to commence insulin following two consecutive glucose recordings above 180 mg/dl (10 mmol/l).

Fluid Balance, Intravenous Fluids, and Diuretics

Following cardiac surgery, particularly that which involves CPB, patients are in a state of moderate overload of extracellular sodium and water (see Chapter 32). Despite this, intravascular volume depletion—due to bleeding, polyuria, and third-space losses—is common.

Maintenance fluid in the form of dextrose 5% may be administered at a low rate (e.g., 0.5 ml/kg/hr) to function as a carrier fluid for drugs and electrolytes. Resuscitation fluid is administered according to the prescribed hemodynamic goals (see Table 17-1). The choice of resuscitation fluid is not important; many units use entirely crystalloid solutions, others a combination of crystalloid and colloid. Within the first 24 hours following surgery, most patients develop a positive fluid balance of 1 to 3 l.

Patients are typically polyuric in the first few hours after CPB but may subsequently become oliguric. Although oliguria may be due to hypovolemia, it is commonly a manifestation of the stress response and shows high circulating levels of antidiuretic hormone. The treatment of oliguria is based on a clinical assessment of the patient’s circulating volume: hypovolemia is an indication for a fluid challenge; hypervolemia is an indication for a diuretic; euvolemia requires no specific treatment.

With conventional cardiac surgery and cardiopulmonary bypass, weight gains of 7.4% and 6.6% above preoperative weight on POD-1 and −2, respectively, have been reported, with wide individual variability.⁴ Furosemide is often administered on POD-1 and continued until the patient has returned to preoperative weight.

The urethral catheter is typically removed after discharge from the ICU on POD-2 or −3. If, due to an inability to pass a urethral catheter, a suprapubic catheter was inserted at the time of surgery, it should be clamped and removed only once the patient has passed a significant volume of urine per urethra.

Prevention of Infection

Typical antibiotic prophylaxis (see Chapter 35) consists of a first-generation cephalosporin such as cephazolin, given intraoperatively. With the increasing prevalence of methicillin-resistant staphylococci, some units have favored the use of vancomycin for routine prophylaxis. A recent metaanalysis indicated that there is no benefit in this approach.⁵ Intranasal mupirocin, commenced preoperatively and continued twice daily for 5 days postoperatively, may reduce the incidence of infection by Staphylococcus aureus in patients who are nasal carriers of this organism.⁶

Other interventions that reduce the risk for nosocomial infection include careful hand washing prior to all patient contact and before entering and leaving the ICU and placing the patient in a semirecumbent position with a head uptilt of 45 degrees. To protect staff members from contamination by infected body fluids, eye protection, gloves, and aprons should be worn during all interventions that could potentially involve contact with body fluids.

Standard Ventilator Settings

Mechanical ventilation is commenced according to protocol and then adjusted on the basis of arterial blood gases, with the goal of keeping the pH, carbon dioxide (P_aCO₂), and oxygen (P_aO₂) tensions within the normal range. Typical initial ventilator settings are as follows:

• Mode: SIMV/Pressure support or Assist/Control

• Tidal volume: 8 ml/kg

• Respiratory rate: 14 breaths/minute

• Inspiratory time: 1.3 seconds

• Positive end-expiratory pressure (PEEP): 5 cm H₂O

• Pressure support or assist: 10 cm H₂O above PEEP

• Fraction of inspired oxygen (F_IO₂) = 100%.

Tracheal Suctioning

Periodic tracheal suctioning of ventilated patients is essential because secretions can build up, causing blockage of small or large airways with resultant atelectasis, impaired gas exchange, and high airway pressures. However, suctioning itself can cause airway trauma, ventilator dysynchrony, hypoxemia, and hemodynamic instability and should be performed only when indicated clinically by coarse or noisy breath sounds on chest auscultation, increased airway pressure, and deteriorating gas exchange. Tracheal suctioning is commonly required at the time of admission to the ICU. Best-practice guidelines for tracheal suctioning are listed in Table 17-3.^7,⁸ Although not indicated for routine suctioning, instillation of 0.9% saline (5 to 10 ml) and hand ventilation with a manual resuscitator are useful if there is acute ventilatory compromise due to mucus plugging.

Table 17-3 Recommendations for Tracheal Suctioning

Suctioning should be performed only when clinically indicated.

Hands should be washed before and after suctioning; apron, gloves, and goggles should be worn during the procedure.

If the patient is awake, the procedure should be explained, and adequate analgesia and sedation should be administered prior to performing suctioning.

The size of the suction catheter should not occlude more than half of the internal diameter of the endotracheal tube.

The inspired oxygen fraction should be increased to 100% for at least 30 seconds prior to and after suctioning.

A ventilator should be used during the procedure, rather than a manual resuscitation bag.

A maximum of two suction passes should be performed, each lasting no longer than 10-15 sec.

The suction catheter should be inserted to the carina and then withdrawn 1 cm before a suction pressure of 10-20 kPa is applied.

The routine instillation of 0.9% saline prior to suctioning is not recommended.

From Day T, Farnell S, Wilson-Barnett J: Suctioning: a review of current research recommendations. Intens Crit Care Nurs 18:79-89, 2002; and Thompson L: Suctioning of adults with an artificial airway. Systematic Review 9. The Joanna Briggs Institute of Evidence-Based Nursing and Midwifery, 2000. http://www.joannabriggs.edu.au.

Waking and Extubation

Once specific criteria have been met, sedation is stopped, ventilatory support is reduced, and the patient is extubated. This process may be performed safely and rapidly according to protocol by the nurse and respiratory therapist, without specific involvement of the ICU physician.^9,¹⁰

Criteria for Stopping Sedation

Sedation can be stopped once the following criteria have been met:

• The patient is hemodynamically stable, is on low-dose or no inotropic support, and has no significant metabolic derangement (pH within the normal range, base deficit <4).

• The patient’s core temperature is 36.5°C or higher.

• The patient’s gas exchange is adequate, with P_aO₂ greater than 60 to 75 mmHg (8 to 10 kPa), F_IO₂ less than or equal to 40%, and P_aCo₂ less than 53 mmHg (7 kPa).

• The patient’s chest drainage is less than 100 ml per hour.

Reducing Ventilatory Support

The exact method of reducing mechanical ventilation is determined by the type of ventilator in use. Most ventilatory modes synchronize spontaneous patient breaths with mandatory machine breaths. As the patient begins to trigger spontaneous breaths, the number of mandatory machine breaths is reduced. Once the patient is taking regular spontaneous breaths, the ventilation mode can be converted to an entirely pressure-supported or assistive mode.

Technique of Extubation

Face-mask oxygen and a self-inflating manual resuscitator and mask should be immediately available. Equipment for reintubation (e.g., laryngoscope, drugs, endotracheal tube) does not need to be in the bed-space but should be readily available.

Once the criteria for extubation have been met, the patient is placed in a sitting position. If there are significant tracheal secretions, they should be suctioned prior to extubation. The patient is asked to inspire fully, the endotracheal tube cuff is deflated, and the tube is rapidly withdrawn. S_pO₂, ECG, and blood pressure should be monitored continuously during the procedure.

Respiratory Care Following Extubation

Once extubated, oxygen at 4 to 8 l/min is administered by face mask. The patient is encouraged to breathe slowly and deeply. Once settled, the patient’s pain score should be recorded and additional analgesia administered if it is indicated. Within a few hours, it may be possible to replace the face mask with nasal cannulas at 2 to 3 l/min. The patient should be encouraged to take deep breaths and to cough with the aid of a rolled towel or sheet clutched to the chest. Incentive spirometry is also helpful.

Even for patients with excellent gas exchange, oxygen supplementation should continue for 24 to 48 hours during the day and even longer at night (i.e., 72 to 96 hours) because of marked nocturnal desaturation for up to 4 days following major surgery.¹¹

Bleeding and Blood Products

Excessive bleeding following cardiac surgery is common and may result from inadequate surgical hemostasis, abnormal blood clotting, or residual heparin (see Chapter 30). The expected volume of postoperative blood loss depends on the duration and nature of the surgery (it is higher for complex aortic surgery than for routine CABG surgery); whether CPB was used; and the preoperative use of antiplatelet or anticoagulant therapy. However, ongoing chest drain loss of more than 150 ml/hr after the first hour is abnormal and warrants further investigation and intervention.

Blood Tests

In any patient who is bleeding excessively, a complete blood count, ACT, and coagulation screen should be obtained urgently. A heparin effect can be rapidly ruled out by performing simultaneous heparinase administration and standard ACTs. A TEG may identify patients with abnormal platelet function, but this test is not available in all centers.

Surgical Reexploration

The decision to surgically reexplore the patient is determined by the severity of the bleeding, whether blood clotting can be improved, and the presence of pericardial tamponade. In the absence of significant coagulopathy, surgical reexploration should be strongly considered if bleeding exceeds 500 ml for 1 hour, 400 ml/hr for 2 hours, or 300 ml/hr for 3 hours or if the patient exhibits signs of tamponade.

Red Cell Transfusion

The transfusion threshold for an individual patient depends on the particular risk for developing complications involving inadequate tissue oxygenation and the rapidity of blood loss. A suggested regime is provided in Table 17-4.

Table 17-4 Guidelines for Transfusion of Packed Red Cells

Clinical Situation	Transfusion Trigger
Patient stable on minimal inotropic support without significant bleeding	Hb <65-70 g/l or HCT <20-22
Patient stable but on moderate-dose inotropic support and clinically important bleeding occurring	Hb <70-80 g/l or HCT <22-25
Patient unstable on high inotropic support with evidence of inadequate oxygen delivery (acidosis, low venous oxygen saturation) and/or major bleeding	Hb <90 g/l or HCT <27

Hb, hemoglobin; HCT, hematocrit.

Blood Component Therapy

Blood component therapy (platelets, fresh-frozen plasma, cryoprecipitate) is indicated for active bleeding in the presence of documented abnormal blood clotting but not for abnormal clotting in the absence of excessive bleeding. The administration of blood component therapy should be protocol-driven so as to avoid unnecessary transfusion and reduce costs. An algorithm based on published protocols and our own practice is shown in Figure 17-1.

Figure 17.1 Algorithm for blood component therapy. PT, prothrombin time; aPTT, activated partial thromboplastin time; TEG, thromboelastograph; MA, maximum amplitude; ACT, activated clotting time.

(Modified from Shore-Lesserson L, Manspeizer HE, DePerio M, et al: Thromboelastography-guided transfusion algorithm reduces transfusions in complex cardiac surgery. Anesth Analg 88:312-319, 1999; and Nuttall GA, Oliver WC, Santrach PJ, et al: Efficacy of a simple intraoperative transfusion algorithm for nonerythrocyte component utilization after cardiopulmonary bypass. Anesthesiology 94:773-791, 2001.)

Chest Drain Management

One or two mediastinal drains are usually placed prior to chest closure. If a mammary artery has been utilized or the pleura has been opened, a pleural drain is usually inserted on the appropriate side. Drains are placed on low-pressure suction at −20 to 50 cm H₂O (−15 to 35 mmHg or −2 to 5 kPa) and connected to an underwater seal. Fluid in the drain tubing may oscillate with ventilation. Bubbling is an abnormal finding and is indicative of: (1) a pulmonary air leak (e.g., due to trauma resulting from a sternal wire); (2) a leak or loose connection in the drain tubing; or (3) air entrainment at the drain insertion site. If a pulmonary air leak is suspected, the chest radiograph should be carefully inspected for evidence of a pneumothorax. Drains should not be removed if they are bubbling.

Removal of Drains

Once drainage has settled to a low level (<100 ml over 4 to 6 hours), drains may be removed. Removal of chest drains is uncomfortable, and additional analgesia should be provided for the process. Drains are taken off suction prior to their removal because after CABG surgery, there is a risk of avulsing a coronary graft if mediastinal drains are removed while still attached to suction. The procedure for each drain is as follows:

1. The patient is placed in a semirecumbent position.

2. The patient is instructed to take a breath in and hold it.

3. The drain is rapidly withdrawn and the pursestring is tied.

4. The patient is instructed to breathe freely.

The risk for entraining air into the chest cavity during drain removal is lower if the patient holds his or her breath on expiration (positive intrapleural pressure) rather than on inspiration (negative intrapleural pressure), but it may be difficult for a patient to hold a breath in expiration for the time required to complete the procedure. Because of the risk for air entrainment if the patient draws a large breath (and creates a very large negative intrapleural pressure) at the moment of drain removal, on balance, it is safer for the patient to hold a breath on inspiration.

Following removal of the drain, the chest radiograph is repeated. If a small pneumothorax is present, it usually represents air entrainment rather than a pulmonary air leak; in such a case no intervention is required. However, a chest radiograph should be performed 12 to 24 hours later to rule out expansion of the pneumothorax.

Pacing and Pacing Wires

Atrial (AAI) or dual-chamber pacing (DDD) is useful to augment hemodynamics and reduce the likelihood of developing atrial fibrillation (see Chapter 21).¹² Some surgeons place epicardial pacing wires in all patients, others do so only when it is specifically indicated. Atrial and ventricular wires may be color-coded or may be distinguished by attaching a suture to one of the chamber’s wires. Atrial wires are typically brought out to the right of the ventricular wires.

Pacing wires are typically removed on POD-3 to −6. If a patient is receiving intravenous heparin, it should be discontinued for 4 hours before pacing wires are removed. If a patient is receiving warfarin, pacing wires should be removed before the international normalized ratio (INR) exceeds 2.5 (see Chapter 30). Even without anticoagulant therapy, there is a small but real risk for tamponade following removal of pacing wires; thus, patients should be closely observed for 4 hours following their removal.

Monitoring and Investigations

While patients are intubated, standard monitoring includes ECG, ST segment analysis, S_pO₂, central venous pressure, invasive arterial pressure, and temperature (see Chapter 8). Many monitors also record exhaled carbon dioxide (capnography) and respiratory rate. From the ventilator, standard parameters include F_IO₂, exhaled minute volume, peak and plateau airway pressures, and dynamic lung mechanics. If a PAC is in place, pulmonary artery pressures must be continuously displayed so that inadvertent wedging can be detected and the catheter withdrawn. PAWP, cardiac output, and S_VO₂ should be recorded every 2 to 4 hours. In the absence of a PAC, S_SVCO₂ may be obtained from the proximal port of a standard central venous catheter in place of S_VO₂. If S_SVCO₂ is used as a monitoring tool, it may be measured prior to critical events such as extubation, in response to hemodynamic instability, or routinely every 2 to 4 hours.

On the morning of POD-1, the arterial catheter and the PAC are removed. The central venous catheter is normally kept in situ for 2 to 3 days for blood sampling and administration of any vasoactive drugs. ECG monitoring by telemetry should continue for a further 48 hours on the ward. S_pO₂ should also be measured, either continuously or intermittently, for 48 hours on the ward. A 12-lead ECG should be recorded on the morning of POD-1 and again prior to discharge from the hospital. A chest radiograph is obtained at the time of admission, following removal of the chest drains, and prior to hospital discharge.

The blood tests that should be obtained during the first 24 hours following surgery are listed in an earlier section. Subsequent to those tests, serum potassium should be checked twice daily on POD-1 and −2. Electrolytes, creatinine and urea, and a complete blood count may also be obtained on POD-3 and again prior to discharge.

Vascular Catheters

On arrival in the ICU all vascular catheters should be inspected, and any old or unused catheters should be removed. Lower-limb venous cannulas are a risk factor for the development of deep venous thrombosis (DVT) and should also be removed as soon as possible. Beyond POD-1 all vascular catheters should be inspected each day for signs of infection. In patients who require prolonged intravenous access (e.g., for endocarditis treatment), a peripherally inserted central venous catheter should be inserted prior to discharge from the ICU. The risk for infection with a peripherally inserted central venous catheter line is significantly less than with a standard central line. Direct atrial lines should be taken out prior to removal of the mediastinal chest drains.

Wound Care

If a radial artery has been used as a bypass conduit, the arm should be elevated, ideally above the level of the heart, for 24 hours. Perfusion in the donor limb is assessed every 1 to 2 hours by comparing color, temperature, and capillary refill to other hand. Once the patient has been extubated, the sensory and motor functions of the affected hand should also be documented.

Leg and forearm wounds should be inspected regularly for bleeding and hematoma formation and, beyond POD-1, for any sign of infection. On POD-2 or −3 dressings are taken down and the wounds are cleaned. Any staples are typically removed on POD-5 to −7.

Reintroduction of Preoperative Medications

Most preoperative medications are reintroduced on POD-1. These include gastric ulcer prophylaxis, statins, asthma medications, thyroxine, anticonvulsants, anti-Parkinson drugs, and many psychiatric medications.

Cardiovascular Medications

If there are no contraindications, β blockers should be reintroduced on POD-1 to prevent β-blocker withdrawal syndrome and as prophylaxis against atrial fibrillation. Modest bradycardia and AAI pacing are not contraindications to restarting β blockers. In patients with a history of heart failure, β blockers should be reintroduced very carefully, usually at a reduced dosage and only once cardiac function is clearly satisfactory. Abrupt withdrawal of calcium channel blockers has been associated with coronary artery spasm following CABG surgery,¹³ so these drugs should be reintroduced on POD-1 or once the patient has been weaned from all inotropic support.

Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and spironolactone can cause problems in patients with low cardiac output and renal dysfunction (see Chapter 3); thus, their reintroduction should be delayed until the patient has been weaned from all inotropic support and postoperative renal function has returned to baseline. Digoxin may be reintroduced on POD-1, assuming renal function is relatively normal, but the dosage should be reduced in patients being treated with amiodarone. Aspirin, clopidogrel, enoxaparin, and warfarin can all be recommenced on POD-1, assuming bleeding is not a concern.

Diabetes Medications

Regular subcutaneous insulin and oral antidiabetic medications may be recommenced once a patient has been established on a full diet and glucose control is relatively stable on an intravenous sliding scale of insulin. Without adequate oral intake, sulfonylureas (glipizide, gliclazide) and meglitinides (repaglinide, nateglinide) have the potential to cause hypoglycemia. Hypoglycemia is unlikely with biguanides (metformin), α-glucosidase inhibitors (acarbose), and thiazolidinediones (rosiglitazone, pioglitazone). Metformin has the potential to cause fatal lactic acidosis, particularly in elderly patients with renal dysfunction and those taking more than 2 g/day. Thus, metformin should not be reintroduced until renal function is stable and creatinine is less than 1.7 mg/dl (0.15 mmol/l).

Central Nervous System Medications

Failure to administer anti-Parkinson medications can lead to acute rigidity, tremor, and even neuroleptic malignant syndrome.¹⁴ Thus, anti-Parkinson medications should be recommenced on POD-1. If extubation has been delayed, a nasogastric tube should be inserted and the medication given by this route.

In general, psychiatric medications can be reintroduced on POD-1 but caution is required in two circumstances. First, the combination of psychiatric drugs that prolongs the QT interval and class III antiarrhythmic drugs; and second, the combination of selective serotonin reuptake inhibitors and other drugs that affect serotonin levels (e.g., tramadol, ondansetron) because of the risk for serotonin syndrome (see Chapter 4).

Long-term Steroid Treatment

Patients on long-term corticosteroid treatment require temporary intravenous supplementation prior to the reestablishment of oral intake (see Chapter 36).

Analgesics

Chronic opioid therapy should be continued throughout the perioperative period so as to avoid acute withdrawal and pain-management problems. Higher dosages, sometimes much higher, of standard postoperative opioids are required in patients who are habituated to opioids. In patients with heart failure or renal dysfunction, nonsteroidal antiinflammatory drugs should be withheld until renal function is stable. COX-II inhibitors should probably be avoided in all patients after cardiac surgery (see Chapter 4).

Mobilization

After uncomplicated surgery, patients may be expected to spend two periods of 1 to 2 hours each in a bedside chair and to ambulate with assistance a short distance within the ICU on POD-1. By POD-3 or −4 patients are typically able to ambulate independently around the ward. The bedside nurse and physical therapist provide education for the patient about how to mobilize safely without putting undue stress on the sternal wound, in particular, without pushing up with the arms.

Nutrition and Bowel Function

Shortly after being extubated patients may be given ice to suck. This may be followed by sips of water 1 to 2 hours later. A light breakfast may be offered on POD-1; if tolerated, it may be followed by regular meals. However, it is not uncommon for patients to have minimal appetite and for food to precipitate nausea and vomiting during the first 1 to 2 days after surgery. If patients have not moved their bowels by POD-3, regular laxatives should be commenced (e.g., lactulose 20 ml twice daily and coloxyl with senna, 2 tablets twice daily).

Prophylaxis of Deep Venous Thrombosis

The incidences of DVT and pulmonary embolus after cardiac surgery are about 20% and 0.5%, respectively, but the likelihood varies considerably, depending on risk factors.^15,¹⁶ Risk factors include delayed mobilization, obesity, increased age, previous history of DVT, and prothrombotic conditions (e.g., myeloproliferative disorders, antithrombin III deficiency, protein C or S deficiency, and factor V Leiden mutation). Routine DVT prophylaxis should include wearing above-knee, bilateral, graduated compression stockings from POD-1 until fully ambulant. Patients at high risk for DVT should probably also receive prophylaxis with either unfractionated or low molecular weight heparin, commencing on POD-1.¹⁷

Reasons for Delayed Discharge From the ICU

Common reasons patients cannot be discharged from the ICU on POD-1 are:

• Hemodynamic instability with the need for significant ongoing inotropic support.

• Respiratory insufficiency manifesting as: (1) the need for noninvasive ventilation; (2) S_aO₂ less than 92% on high flow face-mask oxygen; (3) respiratory distress.

• Evolving renal failure.

In addition, patients with the following problems should be considered for delayed discharge:

• Marked or complete pacemaker dependence. Referral to a cardiologist for consideration of a permanent pacemaker is indicated.

• Perioperative myocardial infarction.

• Ventricular irritability manifesting as more than one episode of sustained ventricular tachycardia/fibrillation or recurrent nonsustained ventricular tachycardia.

• Hyperkalemia (K₊ >5.5 mmol/l), particularly if associated with oliguria or renal dysfunction.

• Disorientation, confusion, or combativeness.

• Advanced age (>80 to 85 years).

Patients who have not met the criteria for removal of their chest drains or who have developed atrial fibrillation but who are hemodynamically stable may still be discharged from the ICU. The need for ongoing low-dose inotropic support is not a contraindication to discharge.

PRESENTING PATIENTS ON ICU ROUNDS

The presentation of patients on the ward round is usually the responsibility of the ICU resident or intern. This presentation should be systematic, logical, and concise. For routine postoperative patients, all that is required is a brief summary, including the following:

• Identification of the patient by name, age, and sex

• Details of the operation

• The preoperative state, including specific mention of ventricular and renal function and any relevant comorbidities

• Overnight progress

• Current cardiac, respiratory, and renal status

• Any other problems

• A suggested plan for the day.

For patients with complicated courses and longer stays in the ICU, a more thorough presentation is required. This should include the following:

• Identification of the patient by name, age, and sex

• The nature and timing of all operations and major interventions

• Relevant history

• A summary of the early postoperative course

• Current active problems

• Results of any subspecialty consultations

• systematic review of current status:

• Cardiovascular

• Respiratory

• Fluids and renal function

• Neurologic status

• Nutrition and gastrointestinal function

• Results of relevant radiology, blood tests, and microbiology

• Other issues if relevant:

• Vascular access

• Medications

• Social situation

• A suggested plan for the day.

FAST-TRACK CARDIAC SURGERY

In an attempt to contain costs, and with the increased use of minimally invasive surgical techniques and shorter acting anesthetic agents, there has been a trend toward earlier extubation and shorter stays in the ICU (and hospital) over the past decade. The term “fast-track cardiac surgery” has been used to indicate extubation between 0 and 8 hours following surgery. Some centers utilize “ultrafast-track cardiac surgery,” in which the patient is extubated in the operating room. With ultrafast-track surgery, the patient either avoids ICU admission entirely or is admitted for only a few hours before being transferred to a step-down unit.

Fast-track techniques can be performed safely and they do result in reduced hospital costs.^18,¹⁹ However, several factors must be considered. First, most cardiac surgery units no longer routinely ventilate patients overnight. Second, ICU costs are substantially reduced by early extubation only if there are facilities that increase throughput and ICU bed utilization. Most patients who are morning cases are extubated in the afternoon or evening, and most afternoon patients are extubated overnight, so it is often not possible to increase throughput unless a “hot bedding” system is used. Finally, with the increasing complexity of the cardiac surgery case mix, early extubation is not suitable for many patients.

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