Anesthetic Management for Enhanced Recovery After Cardiac Surgery (ERACS)

Function

The main goal of the ERACS guidelines is to facilitate the widespread adoption of ERAS-based protocols within cardiac surgery. In building an ERACS program, Noss et al recommend identifying target events of particular interest, such as complications or length of stay. After ascertaining the events of interest, he advocates for identifying the incidence of these events and developing a standardized, evidence-based care pathway. Finally, data must be gathered to assess the efficacy of the implemented pathway.[3] 

For example, Fleming et al implemented an ERACS protocol for elective coronary artery bypass grafting (CABG) and valve surgery. The protocol included ERAS-based strategies such as reducing preoperative fasting, minimizing long-acting opioids, early enteral feeding, and early mobilization. After its implementation, the length of stay was no different from that before its implementation. They found a statistically significant decrease in several complications, such as infection, renal injury, myocardial infarction, respiratory failure, and death.[4]

Issues of Concern

Preoperative Considerations

Glucose control is important throughout the perioperative period. Early preoperative intervention can improve outcomes. Unfortunately, hyperglycemia is common in cardiac surgical patients, with almost 1 in 4 patients having elevated hemoglobin A1c (Hb A1c) and 1 in 10 with undiagnosed diabetes. Elevated Hb A1c is associated with deep sternal wound infection, ischemic events, and mortality. Whenever possible, the Hb A1c level should be below 6.5%.[2][5]

Lower preoperative albumin is associated with prolonged mechanical ventilation, acute kidney injury (AKI), infection, prolonged hospital length of stay, and death. Whenever possible, maximizing nutritional status with preoperative nutritional supplementation before surgery (ideally for 7 to 10 days) is paramount, especially in malnourished patients.[2] In addition, similar to other ERAS guidelines, allowing clear liquids up to 2-4 hours before general anesthesia is generally safe and is not associated with an increased risk of aspiration.[2] Clear liquid carbohydrate loading 2 hours before surgery can reduce insulin resistance and decrease possible inotropic support, which might occur in the post-bypass period.[6][7]

When possible, increasing preoperative patient engagement and functional capacity should be emphasized. Improving patient engagement through education and counseling has been shown to improve outcomes.[2] A preoperative exercise regimen is associated with patients having less perioperative insulin resistance and sympathetic over-reactivity, a reduction in complications, shorter length-of-stays, and faster recoveries.[2]

The preoperative clinic should emphasize the cessation of both alcohol and tobacco. These should be stopped at least 1 month before surgery. Alcohol and tobacco smoking are associated with various complications, such as infection, respiratory issues, slower wound healing, bleeding, and metabolic dysfunction.[2]  

Intraoperative Considerations

The most important surgical site infection in cardiac surgery is the deep sternal wound infection (DSWI). DSWI occurs in about 1 to 4% of cardiac surgery, leading to increased morbidity, mortality, and cost. Staphylococcus aureus (S. aureus) is the most common bacteria involved, with the majority likely originating from preoperative colonization, as up to 30% of cardiac surgery patients are carriers. The ERACS guidelines recommend preoperative intranasal S. aureus therapy, skin preparation (including chest clipping), intraoperative antibiotics that cover S. aureus, and regular postoperative wound and dressing care.[2][8]

Many studies have shown that adequate glycemic control improves outcomes. Maintaining a glucose level below 180 mg/dL in cardiac surgery leads to significantly fewer sternal wound infections. This can be most efficiently accomplished with an insulin infusion. Tight glucose control (ie, 80-110 mg/dL) is not recommended as this may lead to hypoglycemia.[2][8] 

Pain is a significant issue in cardiac surgery and is typically treated with high-dose opioids, which have many side effects. The ERACS guidelines recommend a multimodal opioid-sparing approach to achieve adequate pain control. Medications used for this multimodal approach include acetaminophen, gabapentin (or pregabalin), tramadol, and dexmedetomidine. All of these medications are associated with lower opioid requirements in patients.[2] Opioids and benzodiazepines are generally acceptable but should be minimized if possible. Other medications that have proven beneficial for analgesia but need further research in cardiac surgery include ketamine, lidocaine, magnesium, and steroids.[3] Of note, non-steroidal anti-inflammatory drugs (NSAIDs), such as celecoxib, should not be used in cardiac surgery. Though commonly used in non-cardiac ERAS protocols, NSAIDs are associated with increased thromboembolic cardiovascular risk.[2] 

In addition to medications, various neuraxial and peripheral nerve blocks can be utilized in cardiac surgery. With the use of intraoperative high-dose heparin, neuraxial anesthesia (thoracic epidural and intrathecal opioids) and paravertebral blocks remain controversial. However, studies have shown benefits from these measures in reducing cardiopulmonary complications.[9][10] Alternatively, various peripheral nerve blocks can be used to reduce chest wall pain, and they are gaining popularity. These peripheral nerve blocks generally target branches of the intercostal nerves, which innervate the lateral and anterior chest walls. These blocks include pectoralis nerve blocks (PECS I and II), serratus anterior plane blocks (SAP), erector spinae plane blocks (ESP), transversus thoracic muscle plane blocks  (TTMP), pectointercostal-fascial blocks (PIF), and intercostal nerve blocks.[3][11] The TTMP targets the plane between the intercostal and transverse thoracic muscles, where the left and right internal mammary arteries (LIMA and RIMA) are located. As such, the TTMP block may inadvertently damage the LIMA or RIMA or lead to local anesthetic spillage to the adjacent mediastinal cavities after LIMA or RIMA dissection. Therefore, a more superficial block, such as the PIF block, is likely a safer approach in cases where the LIMA or RIMA is harvested.[11][12]

Normothermia should be maintained after cardiopulmonary bypass and during the initial intensive care period. Hyperthermia (core temperature above 37.9 degrees Celsius) has been associated with cognitive dysfunction, infection, and renal injury.[2] Persistent hypothermia (core temperature below 36 degrees Celsius) can lead to bleeding, infection, longer hospital stays, and mortality.[2][13]   

Bleeding is common in cardiac surgery, and various blood product conservation guidelines exist to minimize unnecessary transfusions. The ERACS guidelines recommend developing a blood product transfusion protocol based on the existing guidelines.[2] One of the guidelines, published by the Society of Cardiovascular Anesthesiologists (SCA), recommends using thromboelastography (TEG) or rotational thromboelastometry (ROTEM) when determining the need for blood product transfusions such as fresh-frozen plasma, platelets, and cryoprecipitate. TEG or ROTEM has been found in various transfusion studies to be superior to conventional coagulation tests.[14] In addition, the ERACS guidelines also recommend using antifibrinolytics such as epsilon aminocaproic acid or tranexamic acid for any cardiac surgery requiring cardiopulmonary bypass. These antifibrinolytics are associated with less blood product transfusion, major bleeding, and cardiac tamponade.[2] 

Sternotomy closure is typically done with wire cerclage, the standard of care for decades. However, several newer rigid plate fixation devices are currently available and have been suggested to reduce side-by-side sternal movement during healing. They are associated with improved bone healing, decreased pain, improved upper body function, and less mediastinitis. Though data and adoption are still limited, a rigid fixation plate device should be considered in high-risk patients. Some high-risk factors include a history of obesity, diabetes, chronic obstructive pulmonary disease, and radiated chest wall.[2][8] 

Postoperative Considerations

Minimizing mechanical ventilation and intubation reduces morbidity, mortality, and cost. Several studies in cardiac surgery have shown that early extubation (within 6 hours of ICU admission) is safe and decreases cost and the length of stays in the ICU and hospital.[2] Further studies are needed to determine whether early extubation reduces morbidity and mortality.

Goal-directed fluid therapy has been shown to reduce complications and length of stay in cardiac surgery. Quantitative measures (such as cardiac index, mixed venous oxygen saturation, urine output, lactate, etc) should guide fluid management to achieve euvolemia.[2][15]

Acute kidney injury (AKI) is fairly common and very costly in cardiac surgery. Identifying patients at high risk for AKI can be difficult. Still, recently, some urinary biomarkers (tissue inhibitors of metalloproteinases-2 and insulin-like growth factor-binding protein 7) can predict AKI early after cardiopulmonary bypass. Using these biomarkers may lead to early AKI risk stratification, early renoprotective intervention, and AKI reduction in cardiac surgery.[2][16][17]

Delirium occurs fairly often in cardiac surgery patients (up to 50% in some studies) and can lead to decreased long-term cognitive recovery and increased mortality and readmission. Regular delirium monitoring and early treatment should be routinely done, with nonpharmacologic treatment as the first-line intervention.[2] Whenever possible, the use of long-acting medications that may contribute to delirium (eg, sedatives, opioids, anxiolytics, etc.) should be minimized. 

Both deep venous thrombosis (DVT) and pulmonary embolism (PE) are likely preventable complications after cardiac surgery. Patients should have mechanical thromboprophylaxis until they are mobile. Chemical thromboprophylaxis should be initiated when surgical hemostasis occurs, ideally from postoperative day 1 until discharge.[2]  

Chest tube clogging is fairly common after cardiac surgery and may lead to pericardial effusion, hemothorax, and atrial fibrillation. One method of unclogging a chest tube is by stripping (or milking), which unfortunately does not work effectively and may be harmful. Another unclogging method includes using a smaller tube to suction the chest tube, which typically involves breaking the chest tube sterility and can lead to infection or iatrogenically cause internal damage. The ERACS guidelines do not recommend either stripping or suctioning, which consists of breaking the sterile field.[2] Alternatively, newer chest tubes with active chest tube clearance methods may be used, as it has shown some promise in reducing chest tube-related complications.[2]

Clinical Significance

Cardiac surgery presents a complicated yet promising target for enhanced recovery strategies. The typically high level of patient comorbidities and the complexity of cardiac surgery require high costs while consuming significant resources.[3] Despite these challenges, there are common modifiable risk factors and feasible interventions to help, as discussed by the ERACS guidelines. Hopefully, the ERACS guidelines can be the foundation for many cardiac surgery programs implementing ERACS-based protocols.

Other Issues

In addition to the above considerations, several common perioperative factors have shown some beneficial effects in cardiac surgery. These factors include investigation of preoperative anemia, higher cardiopulmonary bypass flow to ensure adequate renal perfusion, lung protective strategies for mechanical ventilation, postoperative nausea and vomiting prophylaxis, early postoperative enteral feeding, and early physical rehabilitation.[2][3]

Enhancing Healthcare Team Outcomes

There are many challenges in implementing multifaceted enhanced recovery strategies such as ERACS. Cardiac surgical care always involves a multidisciplinary team effort, from the initial diagnosis to post-surgical recovery. As such, having standardized preoperative, intraoperative, and postoperative protocols for all the team members is crucial in implementing a successful ERACS program. In addition, ERACS is still relatively new, and it is a while before data from large-scale randomized trials are available. To assess the efficacy, it is important to gather as much data as possible for all the relevant events and interventions before and after the ERACS implementation.[3]