Opioid-Free Cardiac Surgery: A Multimodal Pain Management Strategy With a Focus on Bilateral Erector Spinae Plane Block Catheters

CARDIAC SURGERY REQUIRING STERNOTOMY presents unique challenges for perioperative and postoperative analgesia. Intraoperatively, the sympathetic response to surgical stimulation must be modulated carefully to prevent excessive bleeding, maintain the integrity of surgical repairs, and decrease the risk of stroke or iatrogenic aortic injury without compromising myocardial and systemic perfusion. This must be achieved in patients whose underlying abnormal physiology, coupled with the effects of the surgical procedure, often result in tenuous hemodynamics. In the postoperative setting, adequate analgesia is critical to optimize respiratory mechanics and pulmonary toilet, ambulation, and overall recovery.¹ Furthermore, perioperative pain control is a key component of enhanced recovery pathways and prevention of chronic pain.

In light of the opioid epidemic, as well as emerging data surrounding opioid-associated hyperalgesia, anesthesiologists have employed opioid-sparing or opioid-free approaches using regional techniques and nonopioid adjunct medications to minimize or eliminate the use of systemic opioids.^2–7 However, translation of these approaches to cardiac surgery has lagged, in part due to fears over neuraxial bleeding in the context of systemic anticoagulation and hypotension secondary to sympatholysis.^8–10 The introduction of truncal plane blocks outside of the neuraxial space has provided cardiac anesthesiologists with the option of using regional anesthetics without fear of these complications. Groups have studied various plane blocks in an effort to find the most beneficial technique for cardiac surgical patients; however, the evidence is growing still, and large randomized trials are needed. Here, the authors report the successful perioperative management of a patient undergoing major cardiac surgery via sternotomy without the use of any opioids by application of bilateral erector spinae plane (ESP) blocks and nonopioid adjuncts.

Case Presentation

A 37-year-old man, with a history of intravenous heroin use complicated by multiple episodes of bacterial tricuspid valve endocarditis, presented to the cardiac surgery clinic with torrential tricuspid regurgitation. Although asymptomatic, he was developing signs of right ventricular dysfunction and overload, and for this reason he was referred for tricuspid valve repair versus replacement. At this time, it had been approximately 1 year since the patient recovered from substance use disorder and he was concerned about perioperative opioids precipitating drug relapse. For this reason, he requested that opioids be avoided completely. The cardiac anesthesiology team formulated a multimodal anesthetic and analgesic plan in consultation with the regional anesthesia, acute pain, and chronic pain services (Table 1).

Table 1.

Periprocedural Analgesic Strategy

Preoperative	Intraoperative	Postoperative
In holding	Analgesics at induction	Block management
975 mg oral acetaminophen	50 mg ketamine IV	0.2% ropivacaine 8–10 mL/h via ESP catheters (until POD 4)
300 mg oral gabapentin	2 g magnesium sulfate	Analgesics
Preinduction	Maintenance of analgesia	1,000 mg acetaminophen IV q6h transitioned to 975 mg oral acetaminophen on POD 1 (through discharge)
Bilateral ESP block catheters	0.2–0.6 μg/kg/h dexmedetomidine infusion	15 mg ketorolac IV q8h PRN (POD 1-POD 3)
−35 mL 0.2% ropivacaine per side	25 mg ketamine IV at incision and skin closure	Analgesic adjuncts
	2 g magnesium sulfate post bypass	0.4–0.6 μg/kg/h dexmedetomidine infusion (until POD 1)
		300 mg gabapentin q8h (through discharge)

Abbreviations: ESP, erector spinae plane; IV, intravenous; POD, postoperative day; PRN, as needed; q8h, every 8 hours.

Preoperatively, the patient was given oral acetaminophen 975 mg and gabapentin 300 mg. Preinduction bilateral ESP block catheters were placed at T6–7, with an initial bolus of 35 mL of 0.2% ropivacaine. The blocks were performed with the patient in a sitting position. After identification of the correct plane by ultrasound, a needle was inserted in a cranial-to-caudal direction (Fig 1). Local anesthetic was deposited in the plane below the erector spinae muscle, and a catheter was left in position on each side. Block placement was uncomplicated. Intravenous midazolam (4 mg) was titrated during block catheter placement. Induction of general anesthesia was achieved, without complication, with midazolam, lidocaine, propofol, and vecuronium. After induction and intubation, 50 mg of ketamine and 2g of magnesium sulfate were administered intravenously. Additional ketamine boluses of 25 mg each were given before incision and at the start of skin closure (total ketamine dose of 100 mg). An additional 2 g of magnesium sulfate also were administered before separation from cardiopulmonary bypass. Anesthesia was maintained with inhaled isoflurane (end-tidal concentrations ranging from 0.6%-to-1.1%) and dexmedetomidine infusion (0.6 μg/kg/h, no loading dose). Remarkably, with incision and median sternotomy, the patient’s mean arterial pressure rose a modest 15 mmHg, with an end-tidal isoflurane concentration of 1.1% at the time. At no point during his intraoperative course did he require isoflurane concentrations that exceeded his age-adjusted minimal alveolar concentration value to control hypertension, and at no point did he require antihypertensive medications. The dexmedetomidine infusion was maintained throughout the intraoperative course, with the sole exception of being temporarily suspended after a short episode of profound bradycardia (heart rate in low 40s) and associated hypotension (mean arterial pressure <60 mmHg). The hemodynamics responded favorably to an epinephrine bolus of 8 μg and a dose adjustment of the dexmedetomidine infusion, which was restarted at 0.2 μg/kg/h. Before transport to the intensive care unit (ICU), continuous infusions of 0.2% ropivacaine (10 mL/h) were started via each ESP catheter. Overall, the patient underwent an uncomplicated tricuspid valve repair with a good surgical result. He was transported to the ICU, intubated, and sedated with epinephrine, propofol, and dexmedetomidine infusions.

Fig 1.

Ultrasound imaging of the right erector spinae plane block demonstrating the needle tip position (asterisk) immediately posterior to the T6 transverse process below the erector spinae muscle. The paravertebral space also can be visualized. PVS, paravertebral space; TP, transverse process

Upon arrival to the ICU, the propofol infusion was discontinued and the patient was extubated uneventfully within 5 hours. The dexmedetomidine infusion was continued until the morning of postoperative day (POD) 1 (0.2–0.6 μg/kg/h). The multimodal postoperative analgesic plan was centered around the bilateral ESP catheters, which were continued until the morning of POD 4. Of note, last remaining chest tubes were removed on POD 3. Acetaminophen was initially continued as a scheduled medication intravenously, and then transitioned to an oral dose of 975 mg every 8 hours. Once the patient was able to tolerate oral medications, gabapentin was restarted with 300 mg every 8 hours. Fifteen milligrams of ketorolac was administered intravenously 2 hours before extubation and continued every 8 hours until POD 3. Postoperatively, the patient reported adequate pain control throughout his hospital stay. His highest pain score was 7 of 10 using the numerical rating scale, which he reported on the evening of POD 0 and early in the morning of POD 1 (Fig 2). For the remainder of his hospital course, he had no pain scores >5, with the majority of documented scores ranging from 0-to-4. He maintained adequate pulmonary toilet and suffered no respiratory complications.

Fig 2.

Postoperative pain scores and pain interventions. Pain scores are marked throughout the postoperative stay. The duration of continuous analgesic interventions is outlined above, and timing of ketorolac initiation is marked. ESP, erector spinae plane.

Although his hospital course was complicated by intermittent heart block, this ultimately did not require any intervention. He was discharged on POD 6 with a treatment plan of oral acetaminophen and gabapentin for pain control. Notably, he received no opioid medications throughout his hospital stay.

Discussion

In all fields of anesthesiology, there has been a gradual shift toward conscious opioid administration and a proclivity for multimodal approaches to perioperative analgesia. Nonetheless, opioids remain the primary analgesic used for most cardiac surgical procedures. Although uncommon, a small but increasing number of opioid-free cardiac surgical approaches have been reported in the literature.^11–13 These cases have highlighted the variety of reasons why opioids might be excluded or limited in an anesthetic plan, ranging from patients with numerous comorbidities that may be exacerbated by opioid administration, to confirmed opioid allergies or hypersensitivities, to a history of opioid use disorder. All of these reported cases employed a multimodal analgesic strategy to achieve pain control and hemodynamic stability.

In this case, the authors demonstrated the successful use of regional analgesia for cardiac surgery in a patient with a history of opioid use disorder. Regional analgesia is an important foundation of opioid-sparing techniques. Specifically, neuraxial analgesia provides coverage of both somatic and visceral pain and, thus, would likely result in excellent postoperative pain control. However, systemic anticoagulation needed for cardiopulmonary bypass theoretically increases the risk of catastrophic neuraxial bleeding, and for this reason, epidural, spinal, or paravertebral analgesia typically has been avoided in cardiac surgery. Paravertebral blockade also increases risk for pleural puncture and pneumothorax. It is unknown if the fear of neuraxial hematoma is warranted, as the evidence does not suggest an increased neuraxial bleeding risk in patients undergoing cardiac surgery.^10,14–16 Regardless, the ESP block was chosen in this case for 2 reasons—first, to avoid the possibility of neuraxial bleeding complications, and second, to avoid compromising the patient’s sympathetic tone in the postoperative period. The ESP blocks can provide excellent somatic coverage of skin incision, sternotomy, and chest tube sites. Because ESP blocks do not provide visceral coverage, maintaining a nonopioid pharmacologic strategy is critical to achieving adequate analgesia.^17,18

Given that properly performed thoracic epidural analgesia is, in many ways, the gold standard of regional analgesic management (from a pain perspective), Nagaraja et al. compared continuous thoracic epidural analgesia with continuous bilateral ESP blocks for cardiac surgery.¹⁹ They noted comparable pain scores and respiratory mechanics (peak inspiratory flow) in both groups through the first 24 hours postoperatively. Interestingly, the pain scores were better in the ESP group compared with the thoracic epidural group, although both groups had mean pain scores <3. Several recent studies have provided further evidence supporting the use of ESP blocks for management of postoperative pain after cardiac surgery.^20–26 Many of these studies have employed single-shot techniques to avoid the theoretical risk of a pericatheter hematoma, and others have compared continuous catheter-based infusions to nonregional approaches. Although randomizing patients and partially blinding investigators is possible in these studies, the invasive nature of regional blocks makes patient blinding more problematic. Athar et al. successfully blinded patients in a study of single-shot ESP blocks for cardiac surgery by performing sham blocks with normal saline.²⁰ They reported nearly 3-fold longer pain-free duration, slightly shorter time to extubation, and better pain scores in the intervention group compared with the sham group.

The authors elected to use bilateral continuous catheter-based ESP blocks in their patient to achieve longer postoperative pain control. In most studies using single-shot approaches, early pain-free duration was longer than in control group, but the difference between the ESP and control groups became less apparent within 12-to-24 hours postoperatively.^20–22 Attempts to prolong the duration of single-shot blocks have been mixed, as one case report suggested a 40-hour single-shot block duration when supplemented with dexamethasone, and a study using liposomal bupivacaine produced mixed results.^27,28 To the authors’ knowledge, a direct comparison between single-shot and continuous catheter-based ESP blocks in cardiac surgery has not been performed. Thus, it is unknown whether there is actually an increased risk of infectious or bleeding complications with a continuous approach. One would expect, however, that even if bleeding were to occur around the catheter, the consequences of this bleeding would be less severe, as it is external to and not continuous with the epidural and paravertebral space. Toscano et al. noted no significant bleeding complications in a group of 35 cardiac surgical patients at high risk of bleeding (systemic anticoagulation or antiplatelet therapy) who received continuous catheter-based ESP blocks.²⁹ Given the authors’ patient’s strong desire to avoid opioid analgesia, they felt that continuous local anesthetic infusion would most likely improve the duration of his block and decrease the incidence of breakthrough pain. This appeared to be successful, as he required no rescue opioid treatment throughout his stay and had pain scores <5 from POD 1 until discharge. As expected, there were also no postoperative bleeding or infectious complications related to catheter placement.

While planning the anesthetic for this patient, an intravenous lidocaine infusion was considered. Indeed, some prior reports of opioid-free cardiac surgery have described the use of lidocaine infusions as an analgesic adjunct.¹⁴ Ultimately, the authors decided against using lidocaine infusions, as this would have limited their ability to provide dense ESP boluses at the time of catheter placement out of concern for local anesthetic systemic toxicity. In addition, given the mixed data regarding the efficacy of lidocaine infusions as an analgesic adjunct, the authors felt that maximizing the benefit of the regional technique would provide better overall analgesia.³⁰

This case highlighted the importance of patient selection and preparation for any opioid-free technique. The opioid-free anesthesia plan was prepared at the patient’s request, and, thus, he was highly motivated to participate in the plan. The authors contacted the patient before surgery and discussed the anesthesia plan in great detail. This allowed the authors to set adequate expectations for postoperative pain as well as to identify specific clinical features (ie, respiratory compromise or inability to ambulate due to pain) that would warrant reversion to opioid analgesia. Support from the surgical team is also crucial to the success of regional anesthetics, as they often require increased patient preparation time. Increasing patient-driven demand through education and evidence from large trials will further foster support from surgical colleagues. Lastly, the authors found it essential to involve a multidisciplinary team in formulating this plan. Involvement of regional anesthesia, chronic pain, and critical care anesthesiologists, as well as the surgeons, intensive care and floor nursing staff, and pharmacists was crucial in executing the authors’ plan. This is especially important if a clinical pathway is to be created with routine use of regional anesthetics.

As interest grows in opioid-sparing anesthetics, the authors expect that such anesthetic approaches will become more common. In this case, the goal was to achieve a truly opioid-free anesthetic, which is likely not necessary for most patients. Nonetheless, for the broader cardiac surgical population, such cases provide insight into ways to further decrease opioid use, potentially shortening time to extubation, enhancing recovery, and improving patient satisfaction. Further study is necessary to determine which opioid-sparing approaches provide the most benefit for the cardiac surgical population. Furthermore, large trials are needed to determine which patients would benefit the most from an opioid-sparing approach, and which regional technique would be the most effective. Lastly, these approaches will remain few and far between without engagement of the entire perioperative team, including the surgical and critical care staff, and, most crucially, the patients.

Expert Commentary (Dr. Schiller, Dr. Dalia, Dr. Low)

The authors described an opioid-free hospital course for a patient undergoing sternotomy and valve replacement, a feat achieved by using bilateral ESP catheters. It was one of many recent reports and studies that continue to support regional anesthesia as an effective modality for pain control and an anesthetic adjuvant for patients undergoing cardiac surgery. The authors emphasized that proper patient selection and preparation, as well as support from a multidisciplinary care team, are necessary for successful integration of regional anesthesia with cardiac surgery.

Perioperative pain in the setting of cardiac surgery is common and is due to surgical trauma, tissue manipulation, and indirect activation of inflammatory mediators.³¹ It is an underestimated problem³² and has been shown to result in chronic pain in 21%-to-56% of patients.³³ Since the advent of cardiac surgery, narcotics have been the primary modality of pain control.³² However, considering the current opioid epidemic, as well as recent evidence that opioids may result in adverse events and increased hospital costs, there is an effort to pursue other perioperative pain control modalities that may reduce opioid consumption and facilitate quicker recovery.³⁴ Currently, it has been reported that opioid dependence in patients who had cardiac surgery may be as high as 1 in 10, and that narcotics may contribute to both increased hospital length of stay and healthcare costs.^35,36

The use of regional anesthesia in cardiac surgery was first described in 1954 by Clowes et al. with the introduction of thoracic epidural anesthesia patients undergoing cardiac surgery.³⁷ However, neuraxial therapies for cardiac surgery have not been adopted routinely, likely due to potential serious adverse events associated with heparinization.³⁸ Ultrasound-guided nerve blocks have been embraced over the last few decades in many surgical specialties as part of multimodal analgesic regimens, but have yet to become routine practice in cardiac surgery. Ultrasound guidance may help reduce bleeding complications in cardiac surgical patients, and current evidence has indicated that regional blocks are associated with decreased opioid consumption, improved analgesia, decreased time to extubation, improved pulmonary function, and cardio-protection (ie, lower rates of perioperative myocardial infarction), reduced incidence of postoperative arrhythmias, decreased clinical signs of postoperative inflammation, and a lower stress state.^38–41

Regional anesthesia techniques vary depending on the type of cardiac surgery and incision site (eg, sternotomy, minithoracotomy, and device placements). To best understand which type of regional block to employ, one must have a clear understanding of nerve innervation of the chest and surrounding structures. Recent literature has focused on ESP blocks, chest wall infiltrative blocks such as pecto-intercostal fascial plane blocks (PIFB), transversus thoracic plane (TTP) blocks, pectoralis blocks (PECS I and PECS II), and serratus anterior plane (SAP) blocks, as each have their specific application.

The PECS I and PECS II blocks were first described in 2011 and 2012 by Blanco for breast surgery, and they provide analgesia to the upper anterolateral chest wall via inhibition of the medial and lateral pectoral nerve, second through sixth intercostal nerves, and the long thoracic nerves, but they may not provide complete midline sternotomy analgesia.⁴² These interventions have demonstrated significant positive postoperative results including quicker time to extubation and improved pain scores in cardiac surgical patients.^43,44

The SAP blocks can provide anesthesia for the majority of the hemithorax by blocking the lateral cutaneous branches of the intercostal nerves, but like the PECS blocks, they may not provide complete coverage for midline sternotomies.³⁹ These blocks were found to be as efficacious as thoracic epidurals for thoractomies.⁴⁵ The PECS blocks in conjunction with SAP blocks had better pain management, reduced rescue opioids, reduced ICU stay and time to extubation, thus fast-tracking a patient’s postoperative course.⁴⁶ A randomized trial performed by Kaushal et al. compared SAP, PECS, and intercostal nerve blocks in children undergoing bypass via sternotomy or thoracotomy, and found at 4 hours postoperatively the 3 groups had similar pain scores, but the SAP group had lower pain scores and lower opioid usage at hours 6 and 12.⁴⁷ The SAP catheters have even been used successfully for postoperative analgesia for a bilateral lung transplant in 2019.⁴⁸

The PIFB and TTP blocks also have promising results by providing analgesia of the anterior branches of the T2-T7 intercostal nerves, which provide innervation to the mammary region of the chest.⁴⁹ These blocks have been shown to provide adequate analgesia for sternal fractures, anterior chest trauma, as well as for median sternotomy and anterior minimally invasive thoracotomies.⁴² Due to the proximity of the injection to the internal thoracic artery, some surgeons have concerns that these blocks may injure a fresh graft after a coronary artery bypass graft surgery and may increase the risk of infection.⁸

The ESP blocks are a novel approach to mitigate postoperative pain as first described in 2016 by Forero et al. This fascial plane block provides complete ipsilateral hemithorax analgesia and can spread into the ventral rami that covers the T2-to-T6 intercostal nerves.⁵⁰ The ESP blocks have been shown to be equivalent to thoracic epidurals for pain control, duration of mechanical ventilation, incentive spirometry flow rates, and ICU length of stay for cardiac surgical patients.¹⁹ Considering that neuraxial procedures carry a significant risk for the anticoagulated patient, ESP blocks may be an equally efficacious alternative but with a better safety profile. The current 2018 American Society of Regional Anesthesiologists guidelines do not address ESP blocks or thoracic fascial plane blocks directly, rather they recommend considering the vascularity and compressibility of the site for patients on anticoagulation therapy (grade 2C), which may be interpreted as a relative contraindication, not an absolute contraindication.⁵¹ However, Toscano et al. evaluated the safety of single-shot and continuous fascial plane blocks in patients undergoing cardiac surgery while receiving anticoagulant and antiplatelet drugs, and concluded that the risk associated with the use of fascial plane blocks of the chest wall, particularly continuous SAP blocks and continuous ESP blocks, were not increased in patients undergoing cardiopulmonary bypass or treated with postoperative anticoagulation.²⁹ The Austrian Society of Anesthesiology, Resuscitation and Intensive Care does not consider systemic anticoagulation an absolute contraindication to ESP blocks and SAP blocks, and the Canadian experts from the Canadian Anesthesiologists Society have classified the risks of bleeding after SAP blocks and ESP blocks as intermediate and low risk, respectively.^52,53 A recent literature search has not revealed any negative outcomes, negative studies, or negative case reports associated with anticoagulation and ESP blocks. The ESP blocks are successful at reducing opioids and improving postoperative outcomes and reducing ICU length of stay.^20,21,23,25

There remain many opportunities to address lapses in evidence for regional anesthesia in cardiac surgery. First, there may be utility in exploring a combination of blocks (eg, ESP and PECS blocks) to provide more complete analgesia. Second, as these authors have shown that having a catheter for continuous delivery helped tremendously with avoiding not just intraoperative but postoperative opioid use, it may be worth exploring the analgesic efficacy of single-shot versus continuous blocks versus intermittent bolus administration of local anesthetics in these nerve blocks. This was explored partially by Sun et al., as they reported that intermittent bolus ESP blocks resulted in a reduction of postoperative opioid consumption and therapeutic use of antiemetics in patients who underwent cardiac surgery through a lateral minithoracotomy. However, they did not compare continuous versus intermittent bolus therapies. It has been hypothesized by Chen et al. that intermittent boluses have a greater effect because a bolus generates higher injection pressures, facilitating the local anesthetic to go farther over anatomic distances between the catheter tip and the nerve distribution.⁵⁴ Another aspect is the use of liposomal bupivacaine; despite the controversy and conflicting results regarding liposomal bupivacaine, Song et al. recently published a retrospective case control study that showed liposomal bupivacaine for bilateral ESP blocks reduced total opioid consumption intraoperatively, as well as at 4 and 12 hours after extubation in cardiac surgical patients.²⁸

One other area that deserves attention is the timing of block placement. As mentioned previously, the best way to prevent chronic pain is to have aggressive and well-controlled acute postoperative pain management. Therefore, is it best to place the block before surgery? If using a single injection, the amount of time the block will be relied upon postoperatively may be short due to the length of time cardiac surgeries may take, sometimes >6 hours. One must also wonder if the local anesthetic injected is displaced from the fascial plane by surgical manipulation, tissue retraction, surgical incision, or patient position. And yet, waiting to the end of the procedure has its own set of drawbacks, which may include high use of opioids intraoperatively, no patient participation in block placement, disruption of fascial planes, poor ultrasound visualization, possible infection, and possible injury to critical structures. Therefore, studies comparing timing of block placement are necessary.

There are several considerations that are worth noting. First, there is great variation in the type of local anesthetic used, the concentration, the delivery method, as well as the dosage. These variations make it difficult to reliably compare studies and their outcomes. The current local anesthetic shortage, particularly with bupivacaine and lidocaine, also hinders the routine use of regional blocks and highlights a need for studies to identify the lowest dose or volume necessary to obtain good analgesia. Second, it will be important to also identify patients who are most likely to benefit from regional analgesic methods. The earliest efforts should be focused on patient populations at high risk for complications from perioperative opioid use, such as those with respiratory comorbidities, substance abuse, or predisposition to chronic postsurgical pain. Finally, widespread or routine use of regional blocks in cardiac surgery is limited by a host of administrative factors and attitudes, including interest from surgical teams and patients. Herein the authors provided an account of a motivated patient and likely surgical team. Although the learning curve for placing most of these nerve blocks is not steep,⁵⁵ busy clinicians need to be supported in learning and becoming familiar with these techniques. In addition, logistical barriers to performing regional blocks, such as identifying when and where to place them without causing delays to surgical start times, need to be overcome. These seemingly clerical factors and inconveniences fall into the category of negatives in any pro/con debate about the use of regional blocks in cardiac surgery. As a result, they might be worth studying and addressing.

Expert Commentary (Dr. Hamzi, Dr. Fernando)

This case conference highlighted a multimodal pain management strategy to avoid opioid medications in a patient with opioid use disorder in remission undergoing cardiac surgery. Specifically, bilateral ESP catheters were placed, which allowed for the continuous infusion of local anesthetics after the surgery. In addition, several nonopioid adjuncts were administered, including acetaminophen, ketorolac, dexmedetomidine, gabapentin, and ketamine. The authors reported that effective pain control was achieved without the need to administer a single opioid in the perioperative arena.

Opioids often play a central role in providing analgesia perioperatively. However, they are not completely benign medications. In the United States alone there were 47,506 deaths associated with opioids that occurred in 2017.⁵⁶ In light of the opioid crisis, there has been increased scrutiny on opioid prescribing patterns. In the last 20-to-25 years, for example, the number of opioid prescriptions has increased by a factor of 3.⁵⁷ This trend is noteworthy given that 40% of deaths were related to prescription opioids. Hence, the use and prescription of opioids during and after cardiac surgery also must be considered. Brown et al. recently showed that persistent opioid use, defined as ongoing use of opioids between 90 and 180 days after surgery in patients who previously were not using opioids, occurred in 9.8% of patients undergoing cardiac surgery.³⁵ Interestingly, patients who were prescribed >300 mg of oral morphine equivalents appeared to be at higher risk.

This increased awareness regarding the role of prescription opioids has led to consideration of limiting opioids or using nonopioid adjuncts in the perioperative period. Pena et al. studied the effect of a guideline provided to the cardiothoracic surgery team to limit opioids. First, the guideline encouraged using scheduled nonopioid analgesic medications during the hospitalization before use of opioids. Second, the guideline provided a tailored approach by using the amount of opioids received before discharge to inform the decision regarding how many pills should be prescribed upon hospital discharge.⁵⁸ Although institution of the guideline resulted in lowering the number of opioid tablets provided on discharge from 26 to 18, as well as a reduction in the number of unused tablets from 15 to 8, the data did not show reductions in inpatient opioid use or the use of opioids after discharge. Thus, although the guideline appeared to influence opioid prescription practices, it did not seem to translate into a significant reduction in use of opioids by patients.⁵⁸

Although anesthesiologists may not be able to directly influence the inpatient and discharge prescribing practices for opioids, regional anesthesia is one analgesic modality that can be used to decrease opioid use in the perioperative period.⁵⁹ Thoracic epidural analgesia (TEA) provides effective somatic and visceral analgesia by anesthetizing the spinal cord and spinal nerves as they travel through the epidural cuff. With successful placement, epidural catheters provide bilateral, segmental visceral, and somatic analgesia with spread that is partially volume-dependent. The sympathectomy associated with thoracolumbar anesthesia from TEA may confer improved coronary blood flow by causing vasodilatation of stenotic coronary artery lesions⁶⁰ and reduce the systemic surgical stress response to cardiac surgery,⁶¹ but the systemic hypotension and decreased preload also may risk destabilizing patients with existing pulmonary hypertension by mildly reducing right ventricular contractility.⁶² Large meta-analyses comparing patients undergoing cardiac surgery with and without TEA have demonstrated benefits such as reduced pain, lower risk of respiratory complications and supraventricular arrhythmias,^49,63,64 and a lower mortality benefit of TEA.¹⁰ Despite these benefits, there remains significant concern regarding the risk of epidural hematoma in the context of anticoagulation during cardiac surgery; the incidence of which varies widely in reports from several authors. Bracco et al. reported the incidence to be 1 in 12,000, which they concluded was comparable to the risk in nonobstetric patients (1 in 10,000).⁶⁵ Hemmerling et al. studied 16,477 patients who received an epidural as part of their anesthetic for cardiac surgery between 1966 and 2012; there were only 3 cases of epidural hematoma, resulting in an incidence of 1 per 5,493.¹⁵ In another study, Chakravarthy et al. studied 2,113 patients who received epidural anesthesia. Although 4 patients experienced temporary neurologic deficits, attributed to lumbar spread of local anesthetic, there were no cases of permanent neurologic injuries.⁶⁶ Finally, in a meta-analysis by Landoni et al.,¹⁰ there were only 25 epidural hematomas identified in an estimated population of 88,820, resulting in an incidence of 1 in 3,552.¹⁰ Overall, some studies have reported that the incidence of epidural hematoma related to TEA is similar to the risk in nonobstetric patients, whereas others have reported that the risk is greater. Regardless, the fear of this potentially devastating complication has limited universal adoption. In addition, epidural attempts complicated by bloody placement may increase the risk of hematoma and raise discussions regarding delaying surgery, although there are not definitive data to require case cancelation.⁵¹

Given the concerns for TEA, several alternative approaches to chest wall analgesia have been examined in patients undergoing cardiac surgery, including paravertebral block (PVB), intercostal nerve (ICN) blocks, PECS block, SAP block, PIFB, TTP block, and ESP block. The overall goal of each of these alternatives is to avoid any risk of permanent neurologic injury that might be caused by epidural hematoma while still affording patients opioid-sparing analgesia.

The paravertebral space lies adjacent to the vertebral column, and local anesthetic dosed here causes unilateral anesthesia and analgesia by anesthetizing the spinal and sympathetic nerves at multiple levels rostral and caudal from the injection site. The mechanism is quite similar to that of epidurals, with both somatic and visceral coverage, with the notable exception of PVB being unilateral. Most studies of PVB or PVB catheters in cardiac surgeries involving sternotomy employ bilateral block placement for this reason. Literature regarding the use of PVB for cardiac surgery has shown similar benefits to TEA with potentially fewer side effects. Scarfe et al. conducted a large meta-analysis pooling 1,120 patients undergoing cardiac surgery in which PVB catheters were compared with alternatives including TEA, wound infiltration, standard of care, and placebo, and they found no significant difference in analgesia, but lower risks of hypotension, urinary retention, and nausea/vomiting in the PVB group compared with the TEA group.⁶⁷ Similarly, El Shora et al. conducted a randomized trial comparing bilateral PVB to TEA in 145 patients undergoing cardiac surgery, and demonstrated less urinary retention and vomiting in the PVB group compared with TEA, although twice as many patients in the PVB group required rescue analgesia.⁶⁸ Most of the other studies on PVB in cardiac surgery were small trials that seemed to corroborate the above trends of slightly inferior or comparable analgesia compared with TEA with an improved side-effect profile. It is important to note that the American Society of Regional Anesthesiologists recommends PVB be considered in the same category as neuraxial block with regard to bleeding risk, coagulation profile, and anticoagulant medications, given that the paravertebral space is contiguous with the epidural space. The other safety concerns regarding PVB are pneumothorax, given the parietal pleura constitutes the deep border of the paravertebral space, and risk of local anesthetic systemic toxicity, given its high degree of vascularity.⁶⁹

The ICN blocks target individual intercostal nerve dermatomes, which include both the lateral and anterior cutaneous branches to provide lateral and anterior analgesic coverage, including the midline for sternotomy. Due to adjacent level redundant branches, ICN blocks usually are performed at the levels of interest, one level below, and one level above. The high vascularity of the compartment confers higher risk of local anesthetic systemic toxicity with these blocks, particularly when performed at multiple levels, as well as a shorter duration due to more rapid local anesthetic uptake, but they have been shown to be efficacious in cardiothoracic surgery patients. Guerra-Londono et al. conducted a large meta-analysis pooling 5,184 patients undergoing various cardiothoracic procedures, including 4 studies involving procedures with sternotomy, in which ICN blocks were compared with TEA, systemic analgesia, PVB, and others, and showed ICN blocks to be superior to systemic analgesia and noninferior to TEA and PVB with regard to analgesia, although with a significantly more modest reduction in opioid requirements comparatively.⁷⁰ This suggests that ICN blocks may offer similar, but significantly shorter duration of chest wall analgesia, and a major drawback is the multiple, bilateral levels at which they must be performed to provide adequate sternal coverage.

Fascial plane blocks (FPB) have been introduced and studied increasingly over the past decade as a means to target more distal peripheral nerve branches to elicit truncal analgesia without the requirement of visualizing distinct neurovascular structures. The benefit of avoiding the abovementioned risks to the neuraxis is complemented by the relatively favorable safety profile and ease of performance of FPB. However, these benefits come at the cost of visceral coverage, as the sympathetic chain is typically unaffected by these blocks. Given the concerns over systemic heparinization for cardiopulmonary bypass, however, many institutions have studied FPB as a less-invasive analgesic modality for patients undergoing cardiac surgery. One of the first described FPB, the PECS I block, targets the medial and lateral pectoral nerves in the plane between the pectoralis major and minor muscles around the third or fourth rib, and the subsequently described PECS II block adds to this deposition of local anesthetic 1 plane deeper as well, between the pectoralis minor and serratus anterior muscles.⁷¹ Although these blocks were described originally for use in breast surgery, due to the PECS II coverage of lateral cutaneous branches of intercostal nerves 2 through 6, which confers anterolateral chest wall analgesia, they also have been used for minimally invasive cardiac surgeries or cardiac device implantation.⁷² Most studies investigating PECS blocks for cardiothoracic surgery are performed for thoracoscopy or thoracotomy procedures, given the lack of midline coverage. However, Kumar et al. randomized 40 patients to either receive bilateral PECS II block or no block immediately after coronary artery bypass grafting or valve surgery with sternotomy, and demonstrated significantly lower pain scores at rest and with coughing for the PECS group, along with fewer doses of rescue analgesic and higher peak inspiratory flow.⁴⁴ Similar to the PECS II block, but more inferior and lateral is the SAP block, which entails injection of local anesthetic at the level of the fifth rib in between the latissimus dorsi and serratus anterior muscles, or deep to the serratus anterior muscle. The analgesia afforded is quite similar to that of the PECS II, but potentially with more caudal spread. For this reason, the vast majority of cardiothoracic surgery studies examining SAP blocks have been done in surgeries involving thoracoscopy or thoracotomy, where they seem to confer similar analgesia to PVB and TEA, but with shorter duration.⁷² Patients who have undergone surgery with sternotomy may obtain analgesic benefit from PECS or SAP blocks due to coverage of the pain from the thoracostomy tube site, though the parietal pleura is not covered by either. Safety concerns with both of these blocks include inadvertent pneumothorax, although this is reportedly rare.

Most thoracic FPB, including the PECS and SAP blocks, anesthetize the lateral cutaneous branches of intercostal nerves without covering the anterior cutaneous branches. The sternum itself receives the majority of its innervation from the anterior cutaneous branches of the intercostal nerves T2-T6. The PIFB and TTP blocks have been introduced within the past 5 years to directly target these nerve branches as they pierce the muscle planes to course superficially, directly to the side of the sternum. The PIFB is performed in the more superficial plane between the pectoralis major and internal intercostal muscles, and the TTP block between the internal intercostal and transversus thoracis muscles, which is also the plane in which the internal mammary vessels lie. Randomized trials comparing bilateral PIFB or TTP blocks to no block in patients undergoing cardiac surgery have shown mostly significant analgesic benefit with reduced opioid consumption postoperatively,^73–75 with some studies showing benefit in one of these outcomes but not the other.^76,77 It is relevant to note that given how novel these parasternal blocks are, most studies have rather small samples of <50 patients in each arm. Although the comparative analgesic efficacy in one small, randomized trial was shown to be equivalent for PIFB compared directly to TTP blocks in cardiac surgery patients,⁷⁸ one safety concern is that the TTP block carries a potential risk of injury to the internal mammary vessels, which lie in the target plane between the internal intercostal muscle and the transversus thoracis muscle. The other known safety issue is pneumothorax, given the close proximity to the pleura. Because the analgesic effect is unilateral, bilateral blocks need to be performed to adequately cover sternotomy for both blocks. One of the largest trials to date randomized 110 patients undergoing cardiac surgery who received preoperative bilateral PIFB catheters to be dosed with either local anesthetic as the treatment group, or saline as the control group.⁷⁹ The authors demonstrated statistically significant differences across nearly all measured outcomes for the treatment group, including primary outcomes of postoperative rest and dynamic pain scores, and secondary outcomes including intraoperative and postoperative opioid consumption, length of ICU stay, length of hospital stay, time to extubation, urinary catheter removal, and return of bowel function, among others.⁷⁹ Considering the early but consistent data from the literature, and the known physiologic mechanism for providing analgesia for sternotomy procedures through the anterior cutaneous branches, many practices have begun to regularly employ PIFB or TTP blocks for cardiac surgeries as part of an opioid-sparing modality.

The ESP block has been the subject of intense debate in the literature since its original description in 2016, when it was introduced as a novel FPB involving injection of local anesthetic deep to the erector spinae muscle complex at the T5 thoracic level.⁸⁰ This landmark case series detailed its use in 4 patients, 2 of whom had chronic chest wall pain, and 2 of whom were undergoing thoracoscopic surgery. The originally proposed mechanism was local anesthetic spread to the paravertebral space to anesthetize the ventral and dorsal rami, although many studies since that time have come to widely varying conclusions on injectate spread, calling the mechanism into question. Overall, most cadaveric studies demonstrated some evidence of dye spread to the paravertebral space, although often only in a minority of the samples; according to a qualitative review of cadaveric studies, only about 45% of all ESP blocks performed showed obvious paravertebral dye staining.⁸¹ Indeed, some cadaveric studies showed dye staining that was entirely restricted to the erector spinae muscle surfaces and dorsal rami of the spinal nerves, without any spread to the paravertebral space or ventral rami.^82,83 With regard to living patients, one healthy volunteer study corroborated this finding, with 12 volunteers experiencing only posterior cutaneous sensory loss after a single ESP block.⁸⁴ Still, other healthy volunteer studies have been able to show spread to the inter-vertebral foramen, and even the epidural space^85,86 in a manner that would explain some of the somatic and visceral analgesia demonstrated in some studies of preoperative ESP blocks for surgical procedures.^87,88 It is worth noting as well that many studies reported cutaneous sparing of the midline with single-sided ESP blocks that is thought to be due to redundant innervation from the anterior cutaneous branch of the contralateral side, but coverage of the paravertebral space or ventral rami would be expected to cover the entire dermatome of the spinal nerve. Overall, there have been significant inconsistencies in the literature as to the exact mechanisms of analgesia conferred by ESP blocks, even if there seems to be a clinical benefit in many reports. With respect to use in cardiac surgery, ESP blocks have been shown to effectively reduce pain scores and opioid consumption, both in single-shot^20,21 and continuous catheter-based applications,^23,25 although it is relevant to note that the latter 2 studies used historic matched controls, and the Macaire et al. study used a continuous patient-controlled analgesia pump in the control group, thereby confounding some of the basis for reduced opioid consumption. In one of the most relevant prospective trials to date, Nagaraja et al. randomized 50 patients undergoing cardiac surgery via sternotomy to receive TEA or bilateral ESP catheters, and demonstrated the groups had remarkably similar, low pain scores at rest and with cough, incentive spirometry, ventilator duration, and ICU duration.¹⁹ Given the promising data from the case series and small trials, there appears to be analgesic efficacy from ESP blocks that warrants additional study with larger trials. The safety concern of ESP blocks, though reportedly rare, is primarily the risk of pneumothorax. As the sensory block is typically one-sided, bilateral blocks are required for coverage of sternotomy pain. The comparatively lower risk profile of ESP blocks compared with TEA or PVB makes them an attractive option, although more research is still needed to elucidate the actual mechanism of analgesia conferred by the block, and in doing so, determine the most effective approach to performing it.

The authors also chose to use several nonopioid analgesics. Interestingly, the role of ketamine in cardiac surgery has been questioned by some. In a randomized control trial, Cameron et al. investigated the effect of an intraoperative 0.5 mg/kg ketamine bolus, followed by a 0.5 mg/kg/h infusion in patients undergoing coronary artery bypass graft surgery.⁸⁹ They did not find any significant differences in postoperative pain scores or opioid consumption. The benefit of gabapentin in the perioperative period also has been questioned recently. Verret et al. performed a systematic review and meta-analysis that examined the effect of gabapentinoids in surgery.⁹⁰ Notably, only 6% of the patient population involved patients undergoing cardiac or thoracic procedures. Nevertheless, although gabapentinoids were associated with lower pain scores at some time points, the reduction was not considered clinically significant. However, the incidences of visual problems and dizziness were higher with gabapentinoids. The authors thereby concluded that these medications should not be used routinely.⁹⁰ The evidence regarding acetaminophen is mixed in cardiac surgery. In a randomized, blinded, controlled trial, Mamoun et al. found intravenous acetaminophen was superior to placebo regarding pain scores; however, it was only noninferior regarding opioid consumption.⁹¹ Jelacic et al. similarly conducted a randomized, blinded, controlled trial and found that opioid consumption was decreased in the acetaminophen group, although pain scores did not differ.⁹² Finally, dexmedetomidine has been studied in cardiac surgical patients, with possible benefits including improved 5-year mortality and lower incidence of postoperative delirium.^93,94 In contrast, other trials have suggested that postoperative delirium is not reduced.⁹⁵ Furthermore, although the Postoperative and Opioid-free Anesthesia trial was undertaken in noncardiac surgical patients, the decision to end the trial early due to some patients experiencing severe bradycardia is concerning.⁹⁶ Notably, the patient in this case conference experienced an episode of “profound bradycardia” requiring treatment with epinephrine. Nevertheless, dexmedetomidine may have opioid-sparing effects and therefore may be particularly helpful in patients such as the one presented in this case conference when the risk of relapse or fear of relapse in a patient with a history of opioid use disorder also must be weighed.^97,98 Thus, although some may challenge the routine use of these adjunct medications, their use in this case seemed reasonable given the potential benefits for this unique patient.

In summary, the authors presented a case in which an opioid-free analgesic plan resulted in adequate pain control for a patient with a history of opioid use disorder undergoing cardiac surgery. In contrast to single-shot regional analgesic procedures, the implementation of bilateral ESP catheters allowed for a significantly extended duration of local anesthetic infusion, thereby affording postoperative analgesia when mobilization and pulmonary toilet are likely to exacerbate surgical pain and lead to limitations in the recovery course. This was supplemented by multiple nonopioid analgesics both intraoperatively and postoperatively. Overall, the anesthesia team was able to accommodate the patient’s request to avoid opioids while simultaneously providing the patient with a reasonable alternative plan to address pain perioperatively. As demand for opioid-free anesthesia increases, anesthesiologists should consider these strategies when formulating a plan.