Regional Anesthesia for Acute Pain Treatment in Pre-Hospital and In-Hospital Emergency Medicine

Abstract

Background

More than half of all emergency department patients seek help for acute pain, which is usually of musculoskeletal origin. Acute pain is often inadequately treated even today, particularly in children and in older patients. In this study, we assess the potential role of regional anesthetic methods in improving the treatment of pain in the preclinical and clinical emergency setting.

Methods

Pain-related reasons for admission were identified and quantified from emergency admission data. A structured literature search was carried out for clinical studies on the treatment of pain in the emergency setting, and a before-and-after comparison of the pain relief achieved with established vs. newer regional anesthetic methods was performed.

Results

43% of emergency patients presented with acute musculoskeletal pain. The literature search yielded 3732 hits for screening; data on entity-specific pain therapy spectra were extracted from 153 studies and presented for the main pain regions. The degree of pain relief obtained through regional anesthetic procedures, on a nominal rating scale from 0 to 10, was 4 to 7 points for acute back and chest wall pain, >6 for shoulder pain, 5 to 7 for hand and forearm injuries, and >4 for hip fractures. These results were as good as, or better than, those obtained by analgesia/sedation with strong opioids.

Conclusion

Modern regional anesthetic techniques can improve acute pain management in the emergency department and, to some extent, in the pre-hospital setting as well. Pain relief with these techniques is quantifiably better than with strong opioids in some clinical situations; moreover, there is evidence of further advantages including process optimization and fewer complications. Data for comparative study remain scarce because of a lack of standardization.

cme plus

This article has been certified by the North Rhine Academy for Continuing Medical Education. the corresponding questions can be found at http://daebl.de/RY95. The deadline for submission is 30 November 2024.

Participation is possible at cme.aerztebatt.de

Many patients who are seen in hospital emergency departments already suffer from moderate or severe pain that needs to be treated (numerical rating scale [NRS] > 3) before they reach the hospital (1, 2); just under 8% need intravenously administered potent opioids. Multiple studies have revealed that the treatment of pain in the pre-hospital stage is often inadequate. Among patients with fractures around the hip joint, only half obtained pain relief before reaching the hospital, and one-quarter were given no analgesics at all (3). Only 10% of children with fractures received prompt and adequate pain treatment (4), and more than half received none at all (2). Pain therapy is begun an average of two hours after the first contact with the emergency medical team (5). The elderly also often receive inadequate analgesia and have an increased risk of pain-related complications, such as delirium and longer hospital stays (6, 7). Treatment with opioids does not increase the risk of subsequent delirium, but severe pain more than doubles it (8); the risk is even higher in patients with impaired ability to communicate that they are in pain (9). The adequate treatment of pain in emergency medicine is hindered by insufficient structured assessment of pain on well-established scales, neglect of the fact that individuals differ in pain perception, and fear of addiction and drug side effects (10). Nonetheless, adequate pain therapy is a basic human right according to German law (StGB § 323c, Medical Professional Code § 1, para. 2; Safetots initiative based on the UN Convention on the Rights of the Child; www.safetots.org).

Regional anesthetic procedures are well stablished in the hospital setting and yield rapid and reliable analgesia and anesthesia, particularly when performed with the aid of ultrasound imaging. The advantages of these regional techniques when used in the emergency room, compared to intravenous analgesia/sedation, include the following (11):

• patients remain able to understand medical information and give informed consent;

• pain is suppressed enough to enable fracture reduction;

• patients stay in the emergency room for shorter times;

• and subsequent delirium and pain chronification are less common.

For all these reasons, regional anesthetic techniques are increasingly being used in emergency patients, both in the hospital and before they reach the hospital. Any technique used in this setting, unlike the elective setting, must be one that can be performed rapidly and easily with a single injection, often with limited technical aids and suboptimal patient positioning, and it must have a high success rate with a low risk of complications (12).

The aim of this review, based on the findings of a structured literature search, is to evaluate the effectiveness of regional anesthetic treatment concepts in terms of pain relief in painful musculoskeletal conditions that are commonly treated in the emergency setting.

Methods

The most common presenting conditions associated with pain were determined from emergency admission data. Treatment methods were identified with a structured search for literature restricted to the emergency setting, employing the Google Scholar search service and the Cochrane Library and Pubmed databases. The search strings are listed in the eSupplement. The retrieved publications were screened by two independent investigators. The PICO inclusion criteria were used:

• P = Population: emergency patients with specific painful conditions

• I = Intervention: procedure for the relief of pain

• C = Comparison: pain intensity before the intervention

• O = Outcome: pain intensity 30–60 minutes after the intervention, measured on the visual analog scale (VAS) or numerical rating scale (NRS).

The time to the initiation of acute pain therapy is a quality criterion in emergency medicine (13) and is an element of the Manchester Triage System (category orange = physician contact within 10 minutes for severe pain). Effective analgesia must, therefore, be provided early, well before completion of the diagnostic evaluation. This review accordingly does not classify pain by etiology (e.g., acute shoulder pain due to fracture vs. dislocation), and the degree of pain relief is classified by intervention rather than by diagnostic entity. Details concerning each study arm, including technical specifications of the regional anesthetic procedures, are given in the eSupplement.

Statistical analyses were performed with R v4.3.0 (14). For pooled comparisons concerning a single procedure, only prospective studies (randomized controlled trials [RCTs] and before-and-after studies) were considered; these were weighted by sample size and are presented as before-and-after comparisons of study arms. Missing measures of variation were estimated (15–17). The benefit of treatment was rated, wherever possible, with an AHA evidence level (18):

• A = confirmed by multiple RCTs

• B = confirmed by a single RCT or multiple non-randomized studies

• C = confirmed by expert consensus only

The analysis was supplemented by our own experience. This review was registered with the Open Science Framework (https://doi.org/10.17605/OSF.IO/NZXMV).

Results

According to the electronically stored emergency admission data of the Freiberg District Hospital (a tertiary care center), 54.2% of the 25,222 patients who presented in 2019 were suffering from acute pain, which was of musculoskeletal origin in 79.7% (43.2% of all emergency patients). These figures are similar to those obtained in standardized data acquisitions from a group of hospitals in Munich with more than 500,000 patients (19) and from the Klinikum Wolfsburg (20), in which 36% of patients had musculoskeletal pain. Patients with musculoskeletal pain are a plurality of patients with acute pain in the emergency room (Figure 1). The structured literature search (eSupplement), carried out in 2022, yielded 3,732 studies on the identified, relevant causes of musculoskeletal pain; 153 were suitable for statistical analysis and descriptive comparisons in terms of pooled effects. Aspects that could not be covered in this study included the spontaneous course of medical conditions, the effect of personal attentiveness and empathy, other aspects of emergency medical care aside from analgesia, and the specific features of each of the individual studies that were included.

Figure 1.

Painful conditions and their frequencies in emergency patients, by body region. More than half of patients presenting for emergency treatment suffer from pain, and, in 43% of these patients, the pain is of musculoskeletal origin.

Established (non-regional) treatment methods

The various painful conditions seen in emergency medicine were found to be treated with a broad spectrum of classic methods of drug administration by the oral, intranasal, and intravenous routes. Non-steroidal anti-inflammatory drugs (NSAIDs) were often combined with:

• opioids of all degrees of potency

• physical methods (local heat and cold, physiotherapy, Kinesio taping, and transcutaneous electrical nerve stimulation [TENS]), and

• alternative procedures (intradermal injections, acupuncture).

The findings given below indicate the change in subjective pain intensity after the application of regional anesthesia, compared to established treatments, for acute pain in each region of the body (for pain in the head and face, cf. eSupplement-Figure E1).

Back and chest wall pain

Patients generally rate unilateral back or chest wall pain as strong or very strong regardless of its particular site or etiology, whether traumatic or not (e.g., rib fractures, intercostal neuralgia, lumbago). Ultrasound-guided erector spinae plane (ESP) block is a quick and easy way to treat acute pain over multiple segments (21) (eSupplement-Figure E2). In adults, a long-acting local anesthetic is typically injected into the fascial duplication between the erector spinae muscles and the dorsal surface of the transverse processes. This markedly lessens pain over an area extending 2–4 segments above and below the level of injection. ESP block is a technically simple, effective, low-risk procedure that can also be used in the pre-hospital phase if an ultrasound device is available (evidence level B). Hospital admissions for intercostal neuralgia could thus be avoided. Local anesthetic procedures such as trigger point and sacroiliac joint infiltrations are used as well (Figure 2).

Figure 2.

Comparison of different treatments for acute severe back pain and chest pain of traumatic origin

Pooled figures on pain relief compared to baseline (not compared to any reference treatment). Study arms from RCTs with pooled means and 95% confidence intervals of pain reduction (change in VAS score compared to baseline 30–60 minutes after the intervention) were included in the analysis. The effect size for VAS score reduction depends not only on the procedure, but also on the technique, local anesthetic volume and concentration (in all comparative graphs: black = data from multiple RCTs, gray = data from a single trial; study details, including complications, are given in the eSupplement). No., number; ESP block, erector spinae plane block;i.v., intravenously; NSAIDs, non-steroidal anti-inflammatory drugs; pts., patients; RCT, randomized controlled trial; SAP block, serratus anterior plane block; TENS, transcutaneous electrical nerve stimulation; VAS, Visual Analog Scale

Physical interventions can alleviate acute back pain to some extent but do not result in adequate analgesia and are highly labor-intensive. Intravenous opioids are highly effective; we have found, however, that orally administered and locally applied NSAIDs as well as intravenously administered steroids result in no more than moderate pain reduction. Nerve blocks such as the ESP block and trigger point infiltrations had effects comparable to that of intravenous opioids. Paravertebral blocks and other chest wall block, such as intercostal, pectoralis, and serratus anterior [SAP] blocks (eSupplement-Figure E3) are technically more difficult and time-consuming than ESP blocks, and therefore less suitable for acute pain therapy in emergency care. After an ESP block, the patient can usually be rapidly mobilized without any pain or restriction of movement. More data are needed to provide a basis for recommendations on the use of these treatments; standard treatment still consists of transdermal NSAIDs and intravenous opioids (22).

Various types of regional anesthetic block are of known utility in patients with chest trauma. Epidural anesthesia has been used as a standard means of preventing complications in major surgery, with advantages such as better wakefulness and spontaneous breathing, lower rates of atelectasis and pneumonia, and shorter hospital stays (23), but the risk/benefit assessment has shifted in recent years because of the more common use of oral anticoagulation. Similar benefits beyond pain reduction have been described for paravertebral analgesia, after which the risk of delirium is lower by a third compared to conventional pain therapy (24, 25). In a multicenter study of serial rib fractures, epidural anesthesia, paravertebral block and SAP block yielded equivalent analgesia with comparable vital capacity and no differences in mortality (26).

Injuries and pain in the upper limb

Shoulder and arm

The pain is usually severe, and deep sedation or general anesthesia is often required for repositioning (reduction) maneuvers. Local anesthesia is given in the form of intra-articular lidocaine; the regional anesthesia techniques described in the publications that were screened for this article include suprascapular, interscalene (ISB) (eSupplement Figure E4) and supraclavicular blocks (eSupplement Figure E5), as well as superficial cervical plexus blocks (Figure 3). Further techniques include immobilization and special manual reduction procedures without analgesia.

Figure 3.

Comparison of intravenous and inhaled analgesia/sedation, general anesthesia, and local and regional anesthetic procedures for injuries and pain in the shoulder and arm region as pooled changes in VAS scores (before/after comparisions with 95% confidence intervals, 30–60 minutes after the intervention). As expected, suprascapular block was less effective for pain relief. This technique carries the lowest risk but is suitable only for pain relief in the shoulder capsule in the absence of manipulation, because the suprascapular nerve innervates only the dorsal portion of the shoulder joint. No., number; pts., patients; VAS, Visual Analog Scale

Intra-articular lidocaine injection has similar effects to the lower-risk suprascapular block. It significantly shortens emergency room stays (27–29) and lessens complication rates and costs compared to intravenous analgesia. Ultrasound-guided interscalene nerve block, however, yields suitable anesthesia for repositioning, even when the block is performed in less experienced hands, while shortening the emergency room stay by 65% and lessening the time expenditure of emergency room staff by 90% (30). ISB is now considered the best technique for shoulder analgesia in any emergency situation (31). Recent data show its superiority to both analgesia/sedation (32) and general anesthesia (33) with respect to the anesthetic procedure time, the repositioning procedure time, and complication rates (evidence level A).

For patients with fractures, long-acting local anesthetics generally used to cover the entire process of emergency room treatment, surgery and initial postoperative pain therapy, while dislocations can be reduced with the aid of short-acting local anesthetics.

Elbow and forearm

For the reduction of forearm fractures in the emergency room, ultrasound-guided supraclavicular (11) or infraclavicular (34) regional anesthesia allows pain-free manipulation of the arm with high patient and staff satisfaction and a low complication rate. A further advantage of these blocks is easy access without the need for painful repositioning or unclothing maneuvers. Or search did not yield any RCTs with extractable data on acute pain therapy in emergency medicine and only one case report on the successful reduction of an elbow dislocation with an infraclavicular plexus block (35).

In elbow trauma, analgesics are mainly administered per os (36); a hemarthrosis is evacuated (37) and the joint is immobilized (38). Ultrasound-guided supraclavicular blockade (eSupplement Figure E5) is a highly effective method for anesthetizing the entire upper limb. It can suffice not just for acute care (unclothing, reduction, immobilization), but also for subsequent surgery and initial postoperative pain therapy, with high patient and staff satisfaction (39) (evidence level C). In children, additional nasal sedation (and, later, intravenous sedation, if required) may be of benefit. Blocks of single nerves near the elbow joint generally do not yield complete anesthesia sufficient for reduction and surgery proximal to the hand (40).

Radius and Hand

Hematoma and fracture gap anesthesia are established and rapid local anesthetic procedures for acute pain therapy. Alternative methods of alleviating pain of variable severity due to distal forearm and hand fractures include analgesia/sedation (usually opioid-based) and a wide variety of comparatively beneficial regional anesthetic procedures (Figure 4). In the nonsurgical treatment of fractures, local anesthetics shorten the time to suitability for manipulation by 66%, and the total emergency room stay by 37%, compared to analgesia/sedation (e1).

Figure 4.

Comparison of the degree of pain relief achieved with various techniques for hand and forearm injuries. Only 11 studies contained suitable data for comparison. Local and regional anesthetic techniques yielded lower post-interventional pain scores than analgesia/sedation tecniques or even general anesthesia; pooled means and 95% confidence intervals before and 30-60 minutes after the intervention.

No., number; pts., patients; VAS, Visual Analog Scale

Convincing results have been obtained with axillary plexus block (eSupplement Figure E6) and single nerve blocks in the forearm (eSupplement Figure E7). These methods have procedural advantages over the others (Bier block, general anesthesia [e2], hematoma block [e3] (evidence level A). The axillary plexus block enables rapid, painless reduction of distal radius fractures and provides adequate anesthesia for subsequent surgery, if needed. Supra- and infraclavicular blocks can also be used when the abduction is limited due to pain, while blocks of individual nerves near the elbow joint can be used if only pain relief and immobilization are required.

Injuries and pain of the lower limb

Hip and thigh

The advantages of regional anesthesia for acute pain relief in the hip in the emergency setting have now been relatively well studied, particularly the fascia iliaca block (FIB) in elderly patients, even if it has not yet been universally implemented. Ultrasound-guided femoral nerve block (FemB, continuous or single-shot, eSupplement Figure E8), pericapsular nerve block (PENG block, ultrasound-guided), and intra-articular hip joint infiltration are used. Alternative procedures include traction and TENS (Figure 5).

Figure 5.

Comparison of the degree of pain relief achieved with various techniques for proximal femur injuries. Regional anesthetic techniques—in particular, landmark-assisted fascia iliaca block (FIB)—relieve pain better than systemic opiate administration (pooled mean and 95% confidence intervals before and 30–60 minutes after the intervention). Ultrasound guidance apparently yields no additional benefit over freehand technique in FIB; on the contrary, orientation according to anatomical landmarks in the freehand technique apparently not only saves time and effort, but also results in an at least equivalent degree of pain relief. FIB in the hands of non-medical personnel (“paramedics” in the diagram) in the pre-hospital phase also seems to yield early and adequate pain relief, albeit with greater statistical dispersion. i. v., intravenous; No., number; NSAR, non-steroidal anti-inflammatory drugs; pts., patients; TENS, transcutaneous electrical nerve stimulation; VAS, Visual Analog Scale

Robust evidence now indicates that regional anesthesia is superior to opioid analgesia for acute pain near the hip joint (evidence level A). It lowers the risk of many complications, particularly in elderly and multimorbid patients, without impairing the patient’s ability to communicate with medical staff, in particular with regard to informed consent (e4, e5). There is evidence that landmark-guided FIB has an equivalent analgesic effect to FemB, PENG and epidural analgesia while being superior in terms of technique, safety, and efficiency. A 90% success rate was found in a meta-analysis of its prehospital use by non-medical staff (e6). As early as 2014, a review assessed FIB as a first-line pain management procedure that could change the emergency management of proximal femur fractures (e7). Findings from the pre-hospital and emergency room settings have since confirmed the advantages of FIB in the areas of patient satisfaction, risk reduction, and treatment efficiency.

Knee

For injuries in the knee area that are treated with immobilization and hematoma evacuation, intra-articular morphine provides non-significant advantages compared to lidocaine (e8). As for regional anesthetic procedures, FemB has been found to relieve pain efficiently and to enable easy reduction of patellar dislocation in particular (e9). In a comparison across procedures, FemB appears to be the most efficient for acute pain management (evidence level C), yet inadequate evidence is available for situations in emergency medicine beyond immobilization and reduction, so that no qualitative comparisons can be made with pooled analyses. Comparable results (perioperative FemB) can be achieved with landmark-guided FIB (e10). On the other hand, joint punctures for the purpose of either hematoma evacuation or drug injection harbor the risk of joint infection, especially in the case of hemarthrosis.

Leg and foot

Aside from systemic drugs and physical measures, hematoma aspiration and intra-articular lidocaine injection are used. The latter has not been found to differ significantly from analgesia/sedation (e11). Distal sciatic block (DSB, eSupplement Figure E9), a regional anesthetic procedure, has been described as well. It provides sufficient analgesia for the reduction of ankle fractures, for example, without the need to reposition the patient beforehand and without the need for any further pain therapy procedures, with high physician and patient satisfaction (e12). This has been shown in children as well (e13). DIB also has advantages over intra-articular local anesthesia, analgesia/sedation, and spinal anesthesia (e14) (evidence level C). There is a need for further comparative controlled trials on efficiency in the emergency setting, as the currently available data do not enable any pooled comparisons of procedures.

Discussion

The number of studies on pain therapy in emergency medicine has risen markedly in recent years. In a similar systematic review in 2016, only one of the 685 retrieved studies dealt with regional anesthesia (e15), yet the literature search for this review yielded multiple publications on regional anesthesia for musculoskeletal pain alone. Many of them contain adequate quantitative data on pain relief to enable pooled comparisons with established treatment methods. In interpreting the findings, one must be aware of statistical uncertainties: neither a risk-of-bias analysis not a publication bias analysis was possible, because of the multiplicity of techniques used to treat musculoskeletal pain of all causes as well as the lack of standardization of techniques reported in the international literature. The semi-quantitative comparisons presented here should, therefore, be regarded as descriptive.

Regional anesthetic procedures are well established in perioperative medicine, and ultrasound-guided peripheral procedures in particular are increasingly being used because of their relatively low risks and high benefits, including lower morbidity and mortality (e16). In Germany, regional anesthetic procedures in emergency medicine are not yet a guideline standard, but are expected to be included in the S2k guideline on disaster medicine. At the European level, regional anesthetic procedures are already found in guidelines (e17) and are routinely used in some situations (e.g., fascia iliaca block for fractures near the hip joint in 60% of National Health Services [NHS] trusts). The same holds in the USA, where procedural guidelines on procedural standards (e18) and evidence-based recommendations for the use of regional anesthetic techniques in pediatric emergency medicine were issued in 2022 (e19).

Before anesthesia is administered, the intensity of pain, the distal blood flow, and motor and sensory function should be assessed, and the patient should be informed about the technique to be used in whatever manner the emergency situation allows, so that he or she can give informed consent. The treating physician should be well-versed in the recognition and treatment of cardiac and central nervous complications due to high systemic levels of injected local anesthetic; such problems are unlikely in modern ultrasound-guided procedures because of their more accurate targeting and the lower volumes of local anesthetic that are injected.

Other rare complications include:

• injury to surrounding structures (e.g. pneumothorax)

• temporary, undesired dysfunction of neighboring neural structures (e.g. Horner‘s syndrome), sometimes as an inevitable accompaniment

• intravenous injection through failure to identify a vein because of excessive pressure on the transducer

• nerve injury (a risk that can be lowered with the use of special blunt cannulae) and

• infection of the injection site due to inadequate disinfection.

The potential development of compartment syndrome in severe leg injuries is not a contraindication for regional anesthesia for reduction and initial treatment; the duration and strength of the anesthetic effect should be accordingly adjusted, and the limb should be monitored for a possible compartment syndrome.

Conclusion

Musculoskeletal pain is the most common type of pain treated in the emergency room, and it is usually severe. Adequate pain relief is needed both when the affected body part is at rest and, in particular, as a prerequisite for any necessary manipulation. Newer ultrasound-guided regional anesthetic methods yield not only rapid analgesia enabling manipulation, but also anesthesia that suffices for surgical procedures but does not impair the patient’s consciousness or ability to follow medical instructions. Further advantages include shorter patient stays, lower time expenditures by the staff, and fewer complications. Some of these procedures may well make the entire treatment process more efficient if used in the pre-hospital phase. In the emergency room in particular, these benefits can be reaped through close interdisciplinary cooperation. The optimal procedures to be followed in the emergency room will differ from those used under standardized, elective conditions in the operating room.

Questions on the article in Issue 48/2023:

Regional Anesthesia for Acute Pain Treatment in Pre-Hospital and In-Hospital Emergency Medicine

The submission deadline is 30 November 2024. Only one answer is possible per question.

Please select the answer that is most appropriate.

Question 1

What percentage of patients had acute musculoskeletal pain in the data collected in German emergency departments?

1. approximately 10 %

2. approximately 20%

3. approximately 25%

4. approximately 40%

5. approximately 60%

Question 2

Which complications of insufficient acute pain therapy are particularly common in which age groups?

1. shortened hospital stay, respiratory depression – children

2. prolonged hospital stay, delirium – children, the elderly

3. improved mobilization and vigilance – the elderly

4. risk of addiction – children

5. reduced wakefulness – the elderly

Question 3

Which of the following regional anesthetic techniques is not indicated for the treatment of pain in the upper arm and shoulder girdle region?

1. suprascapular block

2. interscalene block

3. supraclavicular block

4. superficial cervical plexus blocks

5. infraclavicular block

Question 4

Which anesthetic technique is preferable for procedural reasons in the emergency treatment of hand and distal forearm injuries?

1. Bier block

2. general anesthesia

3. axillary plexus block

4. hematoma block

5. nitrous oxide sedation

Question 5

Which of the following is the best ultrasound-guided, single-injection technique for inducing complete analgesia of the arm with minimal need for mobilization?

1. supraclavicular block

2. axillary block

3. interscalene block

4. individual nerve blocks around the elbow joint

5. paravertebral block

Question 6

What is the preferred procedure for pain relief in patients with proximal femur fractures (according to a review from 2014)?

1. pudendal nerve block

2. sciatic nerve block

3. fascia lata block

4. fascia iliaca block

5. PENG block

Question 7

According to the text, what group of patients with acute fracture-related pain often receives insufficient treatment of pain, or none at all?

1. adults aged 50 to 65

2. women

3. the chronically ill

4. men in their third decade

5. children

Question 8

Which of the following techniques usually does not result in complete anesthesia for fracture reduction and surgery proximal to the hand?

1. individual nerve blocks around the elbow joint

2. Bier block

3. axillary plexus block

4. general anesthesia

5. supraclavicular block

Question 9

According to the text, what is the best technique for analgesia of the shoulder, regardless of the particular emergency situation?

1. superficial cervical plexus block

2. interscalene block

3. Bier block

4. suprascapular block

5. hematoma block

Question 10

Before any regional anesthetic technique is implemented in emergency medicine,. ..

1. the usual anesthesiologic fasting interval must be observed

2. an anesthesiology workstation with electronic documentation must be available

3. the patient must give informed consent in writing after a legally mandated cooling-off interval

4. distal perfusion, motor and sensory function, and pain intensity should be recorded, and the patient should be given situationally appropriate information

5. an ultrasound device and sterile draping material for surgical field disinfection must always be available