Introduction
Opioid-based anesthesia emerged as a safe and effective way to maintain hemodynamic stability in patients undergoing cardiac surgery in the early 1970s. This traditional anesthetic technique used large doses of long-acting opioids such as morphine and resulted in patients requiring postoperative endotracheal intubation and mechanical ventilation for up to 24 hours. Limitations of morphine-based cardiac anesthesia (typical doses were 0.5 mg/kg to 1.0 mg/kg) included delayed anesthetic emergence and histamine-induced hypotension. In an effort to address these limitations, fentanyl-based cardiac anesthesia (typical doses were 50 mcg/kg to 100 mcg/kg) was introduced in the late 1970s. Fentanyl-based opioid anesthesia gradually became the standard cardiac anesthetic in the 1980s because of its comparatively shorter time to anesthetic emergence and its hemodynamic stability. Titration of short-acting benzodiazepines such as midazolam was subsequently added to this technique in the early 1990s to enhance amnesia, lower the total fentanyl requirement, and shorten the stay in the intensive care unit (ICU).
Throughout the 1990s coronary artery bypass grafting (CABG) case volumes soared and challenged concepts of postoperative care such as hospital costs and resource utilization. Fast-track cardiac anesthesia (FTCA) emerged as a possible solution for streamlining perioperative care with a management protocol for rapid recovery after cardiac surgery. FTCA involves tailoring the anesthetic plan to facilitate tracheal extubation within 6 hours after completion of cardiac surgery. Anesthetic design options to achieve this goal include limitation of the total dose of long-acting opioid and balanced anesthetic techniques with inhalational anesthesia, neuraxial blockade, or both. A vital component for successful FTCA is the systematic implementation of an early tracheal extubation and an accelerated recovery protocol in the ICU.
Options
The current time standard for defining FTCA varies between 4 and 8 hours after ICU admission. Tracheal extubation within the operating room at the conclusion of cardiac surgery is termed ultra-fast-track cardiac anesthesia (UFTCA), and initial series have documented its feasibility and safety in select patients. The possible additional clinical benefits of UFTCA and FTCA include early ambulation and a lower risk of infection through a decrease in ventilator exposure, requirements for invasive lines, and exposure to infection in the ICU setting.
Evidence
Safety of Fast-Track Cardiac Anesthesia
Two large meta-analyses have analyzed the evidence for the safety of FTCA. The first meta-analysis (total N = 1800; 10 randomized trials) reviewed morbidity and mortality in patients undergoing CABG or valve surgery with cardiopulmonary bypass. Clinical trials that included off-pump CABG or neuraxial anesthetic techniques were excluded from this analysis. In this pooled dataset, FTCA significantly reduced the mean time to tracheal extubation by 8.1 hours, and the trend was toward reduced perioperative mortality (1.2% versus 2.7%; p = 0.09). Furthermore, FTCA resulted in equivalent rates of major morbidities such as prolonged ICU stay, stroke, myocardial infarction, major bleeding, sepsis, major wound infection, and renal failure.
The second meta-analysis (total N = 871; four randomized trials) included clinical trials with patients undergoing CABG or valve procedures. Pooled data from all four trials demonstrated that FTCA significantly reduced the length of stay in both the ICU (weighted mean difference, 7.02 hours; 95% confidence interval [CI], −7.42 to −6.61; p < 0.00001) and hospital (weighted mean difference, 1.08 days; 95% CI, −1.35 to −0.82; p < 0.05). Furthermore, FTCA resulted in equivalent perioperative mortality, myocardial ischemia, and risk of tracheal reintubation within the first 24 postoperative hours.
These favorable data from these two meta-analyses have led to the widespread implementation of FTCA. A recent single-center retrospective analysis ( N = 7989) confirmed the safety of FTCA in a real-world setting. In this clinical study, FTCA resulted in equivalent mortality (odds ratio [OR], 0.92; 95% CI, 0.65 to 1.32; p = 0.66), stroke (0.9% versus 1.3%; p = 0.06), myocardial infarction (5.2% versus 5.5%; p = 0.61), and acute renal failure (average incidence, 0.8%; p = 0.84). The investigators concluded that FTCA adds no additional outcome risk in adult cardiac surgical patients.
An important limitation in FTCA is that the landmark clinical trials demonstrating its perioperative safety did not include high-risk patient groups. Collectively, these trials excluded patients with severe left ventricular systolic dysfunction, advanced lung disease, and advanced age (defined as age older than 70 years). Advanced age has been shown to be a risk factor for increased mortality rates and prolonged hospital stays in patients undergoing cardiac surgery. A randomized FTCA trial showed that elderly patients (defined as age older than 70 years) had significantly prolonged tracheal extubation times ( p < 0.03) and hospital stays ( p < 0.001). A second clinical trial confirmed that advanced age remains a risk factor for prolonged hospital stay after FTCA. A third clinical trial ( N = 319) noted that advanced age significantly delayed hospital discharge after cardiac surgery in a rapid recovery model ( p < 0.01). Even in a dedicated FTCA clinical milieu, advanced age remains a significant independent predictor for delayed tracheal extubation and prolonged ICU stay. Anesthetic design can offset some of this excessive risk in the elderly after cardiac surgery. In the elderly, a randomized FTCA trial demonstrated that propofol infusion and limitation of benzodiazepine significantly improved time to tracheal extubation ( p < 0.02), time to readiness for ICU discharge ( p < 0.02), and time to readiness for hospital discharge ( p < 0.04).
Interest is growing in UFTCA, which has been defined as including tracheal extubation in the operating room after cardiac surgery. Although multiple clinical trials have demonstrated the safety of UFTCA, randomized trials demonstrating clear advantages of UFTCA over FTCA are lacking. The emergence of off-pump CABG within the last 15 years has facilitated the implementation of UFTCA. In a large single-center series ( N = 1196), 89% of patients undergoing off-pump CABG with UFTCA were successfully extubated in the operating room. The tracheal reintubation rate was 2.5%. Independent predictors for avoiding operating room extubation included reoperation (OR, 3.9; p < 0.001), pre-existing renal disease (OR, 3.1; p < 0.0001), diabetes (OR, 1.7; p < 0.007), intra-aortic balloon pump placement (OR, 7.4; p < 0.0001), and total surgical time (OR, 3.7; p < 0.0001). Recent single-center series have expanded the scope of this anesthetic approach by demonstrating the feasibility and safety of UFTCA for patients undergoing aortic valve replacement and surgery for congenital heart disease.
Cost-Effectiveness of Fast-Track Cardiac Anesthesia
Given that FTCA is safe, the evaluation of its cost-effectiveness becomes relevant. The costs of a cardiac surgical procedure are significantly determined by operating room time, perioperative complications, and length of stay, in both the ICU and hospital. A randomized trial ( N = 100 elective CABG cases) demonstrated that FTCA reduced total costs per case by 25%. These significant savings were predominantly in reduced nursing and ICU costs. Furthermore, FTCA reduced ICU and hospital length of stay without increasing the perioperative complications, which add significantly to total cost per procedure. A subsequent analysis by the same investigators demonstrated that FTCA significantly decreased resource utilization in the first year after CABG.
The cost-effectiveness of FTCA depends on the implementation of a fast-track recovery protocol in the ICU and cardiac surgical ward. FTCA is an essential component of a cost-effective fast-track recovery model. Reduction of ICU length of stay in FTCA depends on reducing tracheal intubation times but also on a highly efficient hospital staffing model and smooth discharge ICU procedures. This requires multidisciplinary collaboration and effective communication that is the basis for the recommendations in the recent multisociety CABG guidelines ( Tables 42-1 and 42-2 ).
| Recommendation | Class and Evidence |
|---|---|
| Anesthetic management directed toward early postoperative extubation and accelerated recovery of low- to medium-risk patients undergoing uncomplicated CABG is recommended | I (Level B) |
| Multidisciplinary efforts are indicated to ensure an optimal level of analgesia and patient comfort throughout the perioperative period | I (Level B) |
| Efforts are recommended to improve interdisciplinary communication and safety in the perioperative environment (e.g., formalized checklist-guided multidisciplinary communication) | I (Level B) |
| A fellowship-trained anesthesiologist (or experienced board-certified practitioner) credentialed in the use of perioperative transesophageal echocardiography is recommended to provide or supervise anesthetic care of patients who are considered to be at high risk | I (Level C) |
| Recommendation | Class and Evidence |
|---|---|
| Volatile anesthetic-based regimens can be useful in facilitating early extubation and reducing patient recall | IIa (Level A) |
| The effectiveness of high thoracic epidural anesthesia/analgesia for routine analgesic use is uncertain | IIb (Level B) |
| Cyclooxygenase-2 inhibitors are not recommended for pain relief in the postoperative period after CABG | III (Level B) |
| Routine use of early extubation strategies in facilities with limited backup for airway emergencies or advanced respiratory support is potentially harmful | III (Level C) |
The maturation of minimally invasive mitral valve surgery has also resulted in multiple studies that document its safety, outcome advantages, and cost-effectiveness as compared with traditional mitral valve surgery via full sternotomy. This surgical evolution is also under way in aortic valve replacement and off-pump CABG, further reducing operative time and anesthetic requirements and hastening postoperative recovery. This paradigm shift in cardiac surgery will likely continue to result in significant reductions in health resources utilization and enhanced cost-effectiveness. Because UFTCA and FTCA are linked to this changing perioperative cardiovascular paradigm, they will also further contribute to this robust cost-effectiveness.
Optimal Anesthetic Technique for Fast-Track Cardiac Anesthesia
The evidence base for FTCA demonstrates that it is safe and cost-effective, as already outlined. The cardiac anesthetic has evolved significantly since the emergence of high-dose opioid anesthesia in the 1970s and 1980s. In the 1990s, the rapidly growing costs of health care and the soaring volume of cardiac surgery provided the impetus for the birth of FTCA and now UFTCA. The purpose of this section is to review the evidence base for the various anesthetic options in FTCA and UFTCA.
A major trend in FTCA has been to reduce the total dose of the long-acting opioid component of the general anesthetic. Multiple clinical trials have demonstrated the clinical safety and efficacy of this approach with shorter-acting intravenous opioids such as alfentanil, sufentanil, and remifentanil. Although this approach has become important in FTCA and UFTCA, it is essential that the anesthetic design not compromise postoperative analgesia. Adequate pain control is essential to safe FTCA. Increased pain will expose patients to unnecessary tachycardia and myocardial oxygen demand, putting the patient at risk for myocardial ischemia.
Intrathecal morphine has been studied as a component of FTCA for its ability to both reduce the systemic opioid dosage and provide sustained postoperative analgesia. A recent meta-analysis (cumulative N = 1106; 25 randomized trials) documented that spinal analgesia in cardiac surgery does not significantly reduce perioperative mortality (risk difference, 0.00; 95% CI, −0.02 to 0.02; p = 1.0), perioperative myocardial infarction (risk difference, 0.00; 95% CI, −0.03 to 0.02; p = 0.77), and hospital length of stay ( weighted mean difference, −0.28 days; 95% CI, −0.68 to −0.13; p = 0.18). Given the concern about neuraxial hematoma in anticoagulated cardiac surgical patients, the investigators concluded that these neutral data discourage further randomized clinical trials of spinal analgesia for cardiac surgery. Furthermore, a recent meta-analysis of remifentanil in cardiac surgery (cumulative N = 1473; 16 randomized trials) demonstrated significantly decreased duration of postoperative mechanical ventilation (weighted mean difference, −139 minutes; 95% CI, −244 to −32; p = 0.01), cardiac troponin release (weighted mean difference, −2.08 ng/mL; 95% CI, −3. 93 to −0.24; p = 0.03), and hospital length of stay (weighted mean difference , −1.08 days; 95% CI, −1.60 to −0.57; p < 0.0001). Despite these advantages, remifentanil exposure did not significantly reduce perioperative mortality (OR, 0.76; 95% CI, 0.17 to 3.38; p = 0.72).
The role of thoracic epidural analgesia (TEA) in FTCA has also received considerable recent attention. A recent randomized trial in off-pump CABG ( N = 226; single-center) demonstrated that TEA as a component of FTCA significantly reduced arrhythmias (OR, 0.41; 95% CI, 0.22 to 0.78; p = 0.006), median duration of mechanical ventilation (hazard ratio, 1.73; 95% CI, 1.31 to 2.27; p < 0.001), perioperative pain (OR, 0.07; 95% CI, 0.03 to 0.17; p < 0.001), and hospital length of stay (hazard ratio, 1.39; 95% CI, 1.06 to 1.82; p = 0.017). In contrast, a second recent randomized controlled trial demonstrated that TEA as a component of FTCA failed to reduce important clinical outcomes such as mortality, stroke, myocardial infarction, pulmonary complications, and renal failure either at 30 days ( P = 0.23) or at 1 year ( p = 0.42) postoperatively. An accompanying editorial suggested that the evidence base currently supports TEA in FTCA for quality of postoperative recovery rather than for major organ-based clinical outcome improvement.
This controversy about TEA as a component of FTCA has not been resolved by recent meta-analyses. The first recent meta-analysis (cumulative N = 2366; 33 randomized trials) determined that TEA in cardiac surgery reduced duration of mechanical ventilation (weighted mean difference, −2.48 hours; 95% CI, −2.64 to −2.32; p < 0.001), mortality and myocardial infarction as a composite endpoint (OR, 0.61; 95% CI, 0.40 to 0.95; p = 0.03), and the risk of acute renal failure (OR, 0.56; 95% CI, 0.34 to 0.93; p = 0,02). In contrast, the second meta-analysis (cumulative N = 2731; 28 studies) demonstrated that TEA in cardiac surgery did not reduce mortality (risk ratio, 0.80; 95% CI, 0.40 to 1.64), myocardial infarction (risk ratio, 0.80; 95% CI, 0.52 to 1.24), and stroke (risk ratio, 0.59; 95% CI, 0.24 to 1.46). In this analysis, TEA did significantly reduce the risk of respiratory complications (risk ratio, 0.53; 95% CI, 0.40 to 0.69) and arrhythmias (risk ratio, 0.68; 95% CI, 0.50 to 0.93). This ongoing controversy in the evidence base for TEA in FTCA is the rationale for the Class IIb recommendation in recent multisociety CABG guidelines (see Table 42-2 ). Furthermore, the risk of neuraxial hematoma cannot be assessed in this evidence base because the cumulative cohort size is still too small.
The possibility of UFTCA with high TEA as the sole anesthetic has recently gained attention. Although this technique is feasible and appears safe so far, current trials demonstrate that it is still in the pilot phase. This type of FTCA has not yet become part of mainstream practice; thus it cannot be advocated at this point.
Transcatheter Aortic Valve Replacement and Fast-Track Cardiac Anesthesia
Patients with severe aortic stenosis and excessive operative risk are now eligible for transcatheter aortic valve replacement (TAVR), principally via the transfemoral and transapical approaches. This revolutionary therapy has given high-risk patients the option to receive a prosthetic aortic valve replacement without the stress of sternotomy and cardiopulmonary bypass. Because TAVR uses a minimally invasive surgical approach, the role of FTCA and UFTCA has been discussed and debated. Because transapical TAVR requires a minithoracotomy for surgical access to the left ventricular apex, the typical anesthetic design has entailed a balanced general anesthetic. Transarterial TAVR via the subclavian or femoral approach is feasible with general anesthesia or sedation with a local anesthetic. The choice of anesthetic technique varies according to patient criteria and heart team preference and experience.
Sedation for transarterial TAVR is not only feasible but it can also improve cost-effectiveness and shorten patient recovery. A limitation of this technique may be the difficulty in performing transesophageal echocardiography. One solution is to use transesophageal echocardiography during transarterial TAVR with noninvasive ventilation that uses a tailored mask. A second solution is to relinquish imaging with transesophageal echocardiography in this setting, as it is not absolutely required during transarterial TAVR because the prosthetic valve can be adequately positioned with fluoroscopy. A second limitation of sedation for transarterial TAVR is the significant possibility of procedure-related complications requiring urgent conversion to general anesthesia ( Box 42-1 ). Furthermore, in addition to procedural complications, general anesthesia may be indicated when patient suitability for sedation may be significantly compromised by comorbidities such as borderline mental status, chronic back pain, severe chronic lung disease, and morbid obesity.
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