Pain Control with Regional Anesthesia in Patients at Risk of Acute Compartment Syndrome: Review of the Literature and Editorial View

Introduction

Despite the many well documented benefits associated with regional anesthesia in pain management as compared to opioids, controversy remains surrounding its use in certain settings where acute compartment syndrome is of concern. This includes post-trauma pain management in the emergency room as well as perioperative acute pain management. The medical management of trauma patients is a fundamental component of the practice of medicine. Trauma accounts for almost thirty percent of all life years lost in the US, which is greater than the combination of cancer, heart disease and HIV.¹ The treatment of trauma patients must continue to advance. Given the variety of traumatic injuries as well as the economic burden of these patients which accounts for over $400 billion annually in the United States, new methods and treatment options should be considered and developed.² One of these being the institution of regional anesthesiology nerve blocks and to lay to rest the speculation about their safety. Use of regional techniques in trauma patients, however, has been a controversial topic since the start because these patients are at higher risk of acute compartment syndrome (ACS) that can occur in many parts throughout upper extremity, lower extremity, and abdomen (Table 1). Those that argue against the use of regional anesthesia in these cases argue that hiding or blunting pain can mask one of the presenting symptoms of ACS.³ In this review, we argue in favor of the use of regional anesthetic techniques in trauma patients, specifically in favor of single-shot or lower doses of continuous peripheral nerve blocks over epidural or patient controlled analgesia (PCA).

Table 1 Compartments of the Body and Their Innervation. This Chart Also Lists the Most Common Causes of Compartment Syndrome by Upper Extremity, Lower Extremity, and Abdominal Divisions, as Well as Possible Pain Control Modalities in These Areas

Pain management in trauma patients is often disregarded and sidelined in favor of saving the life/limb of a patient. In the cases where pain management can be addressed, systemic opioids are by far the most utilized option given their potency and effectiveness in managing generalized pain. However, systemic opiates bring about secondary consequences that may hinder the provider’s ability to stabilize a patient. Many opiates lead to vasodilation and hypotension which is detrimental to a patient in shock. Moreover, in patients with altered mentation, the effects of respiratory depression and subsequent airway compromise may also be detrimental to these patients. The myriad of patient presentations that stem from trauma in combination with opiates are difficult to manage including polysubstance/baseline altered mentation which may be exacerbated with opiates. An accurate neurological exam is crucial especially in head trauma patients which can be skewed in the context of these medications. On a structural level, the variety of providers in an Emergency Department and staff turnover makes continuity and assurance of proper medical management difficult in these acute settings which can either lead to olio-analgesia or to overdosing patients on opiates.⁴

Regional Blocks

In the surgical setting, the implementation of regional anesthesia has yielded tremendous results both for intra and postoperative management of patients. The ability to provide site-specific analgesia allows for fewer systemic medications to be utilized which bring about their own side effects including sedation and hemodynamic changes. There have been multiple studies that demonstrate the benefits of the utilization of site-specific anesthesia including improvement in wound healing, decreased stressed responses on cardiovascular symptoms, and improved localized blood flow—all components that would be beneficial to trauma patients.¹ From an institutional standpoint, there are also financial incentives as an enhancement in patient recovery will allow for an earlier discharge and shorter duration of hospital stay.⁵

Nonetheless, the widespread implementation of regional blockades into common practice has not occurred due to several concerns from trauma surgeons/providers. Given certain patient presentations, neurologic exams are crucial to determine motor and sensory deficits from trauma which are often evaluated throughout patient care: from preoperatively, intraoperatively, and postoperatively. As such, the utilization of regional blocks may distort accurate patient exams as the effects of local anesthetic blockade can alter sensorium and muscle strength. This can put these patients at increased risk for falls. In addition, the effectiveness, duration, as well as variety of blocks utilized is operator dependent. Consequently, the variability in patient results unfortunately alters the general perception of the utilization of this modality in this patient care setting. Aligned with the operator dependent efficacy of regional blockades, the timing of doing these factors is often a concern for surgeons. In most surgical settings, regional blockades are well integrated into the flow of a surgery where the anesthesiologist provider has the time to appropriately perform the procedure. However, in the setting of trauma patients, there may be concern for delayed starts to the operating room.⁶

Compartment Syndrome

One of the greatest obstacles to the universal implementation of regional anesthetics into trauma surgery is the concern of compartment syndrome. Compartment syndrome involves the accumulation of bleeding/swelling of tissues within anatomical compartments that leads to high pressures. This can decrease blood flow and lead to substantial damage to surrounding nerves, muscles, and tissues.⁷ It is associated with all forms of trauma, from orthopedic, vascular reperfusion injuries/hemorrhages, and crush injuries of the soft tissues, to iatrogenic etiologies such as from arterial/venous puncture in anticoagulated patients. This pathology is a medical emergency that can be easily managed with a fasciotomy but requires emergent treatment to prevent permanent damage.⁸

The incidence of compartment syndrome occurring after injuries is approximately 3.1 per 100,000 with a predominance in younger males (30–35 years old) with larger muscle masses stemming from high energy activities/accidents.^9,10 The most common injuries leading to compartment syndrome are tibial shaft fracture, soft tissue injury, and forearm shaft fracture.^11–13 In the pediatric population, older male trauma patients, those who experience firearm injury, and lower limb fracture have increased risk of compartment syndrome.¹⁴ Another subset of the patient population that experiences compartment syndrome is the geriatric population, where initial clinical presentation can be easily masked by multiple medical comorbidities and altered mental status.¹⁵

The diagnosis of compartment syndrome is clinical and traditionally revolves around six signs and symptoms including pain, paresthesia, paresis, pallor, pulselessness, and poikilothermia.¹⁶ Paresthesia is often the earliest sign of compartment syndrome and should prompt urgent evaluation to ensure a good outcome. Given higher risk demographics, the age and gender of patients is also important in appropriately diagnosing this pathology. From there, the mechanism of injury should be evaluated to help direct patient management. The utilization of a transducer catheter can help confirm the diagnosis if the pressure of the area of concern is more than 30mmHg. An intercompartmental pressure of 10mmHg to 30mmHg of the patient’s diastolic blood pressure can also be indicative of inadequate blood perfusion and relative ischemia.^17,19

The diagnosis of compartment syndrome in pediatric patients can be a challenging one, particularly in those who are non-verbal or unable to fully communicate their symptoms. In this population, the 3 A’s (anxiety, agitation, and increased analgesic requirements) are often cited as presenting symptoms instead of the traditional symptoms seen in the adult population.¹⁸ There are also reports of “silent” compartment syndrome in pediatric patients, where patients present with painless swelling and are found to have elevated compartment pressures when taken to the operating room for fasciotomy.¹⁹

With continued integration of regional anesthetic into the standard of care, there remains some concern that local nervous blockade can inhibit/delay the diagnosis of compartment syndrome. There is a paucity of randomized controlled trials on the effect of regional anesthesia on compartment syndrome, but one study by Chen et al took healthy volunteers randomized to receive adductor canal block alone or in conjunction with either low or high concentration sciatic nerve block to see if the blocks affected the patients’ ability to sense 6/10 pain induced by prolonged pressure.²⁰ This study showed that all blocks increased the pressure-pain threshold to varying extents. Further study through randomized controlled trials is necessary.

Statements from Major Anesthesia Societies

A literature review by E. Driscoll in 2016 evaluated 34 articles with the majority (75%) demonstrating that regional anesthesia did not put the patient at an increased risk of delayed diagnosis of compartment syndrome.^7,8 In evaluating these patients who had a diagnosis of compartment syndrome, there were more than enough clinical presentation factors that would be of concern to evaluate for this pathology. However, it was found that neither regional anesthetics nor the implementation of Patient Controlled Analgesia (PCA) contributed to this.⁷ The efficacy of regional anesthesia has made leaps and bounds with improvements in ultrasound technology and user skill set, leading to a more accurate placement of local anesthetics which also allows for lower concentrations to be utilized.

In Table 2, we detail all cases of compartment syndrome with regional anesthesia, PCA, or epidural anesthesia found in the literature and whether these modalities of pain control were seen as contributing to delayed diagnosis of compartment syndrome. In several case reports, there have been concerns that peripheral nerve blocks lead to the delay in the diagnosis of compartment syndrome although these claims are often unjust or inaccurate. There have been additional case reports that attribute epidural anesthesia and patient-controlled analgesia pumps to the delay of compartment syndrome diagnoses.²¹ In contrast, other studies support the claim that peripheral nerve blocks aid in diagnosis, as they do not completely block ischemic pain, therefore if a patient with a nerve block is having pain out of proportion to exam, it is more likely a pathologic process.^22,23 Fundamentally, ischemic pain cannot be completely categorized as nociceptive and neuropathic as there is likely a sympathetic component which follows blood vessels and nerves. As such, there is the need to question the likelihood of completely blocking ischemic pain through regional anesthesia where systemic opiates (spinal/supraspinal) and epidurals may likely have greater/systemic effects than peripheral nerve blocks.²⁴ Consequently, it would be more prudent to determine what patients are being offered for pain management in these cases rather than focusing on regional anesthetics as the sole offender for delayed intervention.²⁵

Table 2 A Summary of Current Case Reports on Compartment Syndrome

Table 3 further details the existing society statements on use of regional anesthesia when compartment syndrome is likely or present. Although there is no universal consensus, the Association of Anesthetists of Great Britain and Ireland have stated that compartment syndrome is not a contraindication for usage of regional anesthesia modalities.³ Pain is not the only criteria for its diagnosis. Another factor being that patient’s complaints of pain are subjective and are not a reliable benchmark for an instant, definitive diagnosis.³² With this mindset that there is no evidence that regional anesthesia increases risks/delays acute compartment syndrome, the European Society of Regional Anesthesia and Pain Therapy (ESRA) in conjunction with the American Society of Regional Anesthesia and Pain Medicine (ASRA) joint committee have helped establish guidelines for best practices in pediatric patients²⁶ (Box 1).

Box 1 ESRA and ASRA Joint Committee Statement

Table 3 Summary Table of World Society Guidelines on Use of Regional Anesthesia and Its Effect on Compartment Syndrome

In addition to the primary concern for compartment syndrome, local anesthetic blockade is not a simple procedure without any risks in which patients receiving these procedures should be evaluated on a holistic basis prior to proceeding. Local anesthetic systemic toxicity is a low risk but nonetheless should be monitored especially in cases that require multiple catheters and infusions which can be further complicated by periodic boluses. Patients prior to regional anesthesia may also present with pre-existing nerve injuries which may be challenging to determine an accurate assessment of the blockade. Coagulopathies and bleeding risks are also considered in addition to infections which are concerns for any interventional procedure.

Conclusion

The practice of acute pain management is not simply the utilization of regional blockade, but rather a comprehensive multimodal approach to anesthesia and analgesia. The addition of standard medications including acetaminophen and nonsteroidal inflammatory drugs are fundamental tenets of pain management which can be further supplemented by additional regiments including dexmedetomidine and ketamine which has gained recent popularity for its analgesic effects. Benzodiazepines also have utility as medications such as valium have been extremely helpful in reducing muscle spasms in patients post-operatively. This multimodal approach of usage of a variety of medications and nerve blockades helps in many aspects. This approach minimizes the utilization of opiates and their unwanted side effects and helps improve patient clinical outcomes and satisfaction.

Trauma pain management has substantial importance and should continue to evolve to help improve patient outcomes. With substantial improvements in regional anesthesia and greater integration into clinical practice, anesthesiologists are in a unique position to become more involved in trauma pain management in multimodal format. Given some concerns with the use of regional blockade for acute compartment syndrome diagnosis, it should be noted that peripheral nerve blocks would be the preferred method for pain management rather than usage of patient-controlled analgesia or placement of an epidural.²⁷ The practice of medicine is a team effort and the incorporation of new innovative procedures aligned with improved patient communication and medical colleagues is key to ensuring clinical improvements, particularly in patients at risk for the development of acute compartment syndrome.