CPD Articles

Regional anaesthesia for district hospitals and clinics

Michele Torlutter

Received: 17 Nov. 2023; Accepted: 23 Apr. 2024; Published: 28 June 2024

Copyright: © 2024. The Author(s). Licensee: AOSIS.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Pain is a common reason that patients seek care in the emergency department (ED). Regional anaesthesia in the form of nerve blocks provides an excellent alternative to traditional forms of analgesia, and may be superior in managing musculoskeletal pain compared to opioids. Adequate pain management improves patient satisfaction, facilitates examination and minor procedures, and allows for earlier and safe discharge. In low resource settings this modality is underutilised due to lack of trained providers and/or support from specialised services, shortages of equipment, and lack of context-sensitive guidelines. Advances in ultrasound guided regional anaesthesia has the potential to improve access to safe and reliable anaesthesia. It is often not accessible or an active part of training even for emergency physicians. There are, however, a number of nerve blocks that are easy to learn, don’t require specialised equipment, and can be readily applied in EDs for minor procedures and longer acting forms of analgesia. Nerve blocks more applicable in the operating theatre or best done under ultrasound guidance are mentioned but not discussed in this article. This continuous professional development (CPD) article aims to provide guidance with respect to several key areas related to more commonly used types of regional anaesthesia in district level services. We discuss the importance of good clinical practice including thorough preparation of equipment and the patient to avoid common complications, clinical indications for regional blocks in the ED, local anaesthetic agents, different techniques for some common regional blocks, potential complications, and the need for a trained interprofessional team.

Keywords: low-resource countries; regional anaesthesia; ultrasound-guided nerve blocks; anaesthesia safety.

Introduction

A regional block is a specific anaesthetic technique that is used to infiltrate a peripheral nerve with local anaesthetic (LA), thereby blocking nerve transmission to avoid or relieve pain.¹ It is different from general anaesthesia (GA), which includes the triad of hypnosis and muscle relaxation and analgesia, as it does not affect the patient’s consciousness level to relieve pain.

Different types of regional anaesthesia (RA) may include local blocks, peripheral nerve blocks, nerve plexus blocks, intravenous RA and neuraxial (epidural and spinal) blocks. When effectively delivered, regional blocks can provide sufficient analgesia to carry out surgical procedures. Combining a local block and light sedation (such as ketamine) provides a good alternative to GA for minor procedures. They are also used to augment GA providing additional analgesia that can last hours to days.² Nerve blocks are already commonly used in operating theatre environments and are now being used more frequently in emergency departments (ED) as an alternative to traditional methods of analgesia. This provides an accessible, safe and cost-effective alternative, particularly in low-resource settings such as sub-Saharan Africa, where safe and accessible surgical and anaesthetic care, is often limited.^3,4 Adaptive leadership, training and adoption of regional techniques has lagged in developing countries despite it being a well-recognised option for over a decade with many potential benefits. In ED, musculoskeletal pain is a common and frequently neglected complaint. Regional blocks can safely be used for a variety of pathologies, sparing the use of opioids and shortening time to discharge in often overcrowded EDs.⁵ Additional advantages include avoidance of airway manipulation, reduced doses and side effects of systemic drugs, faster recovery time and significantly lower pain levels after surgery.⁶ Ultrasound-guided RA is not yet part of the formal training of emergency medicine registrars in South Africa, and certainly trained providers are very scarce in the district services. This continuous professional development (CPD) article aims to provide guidance on a few aspects of RA, addressing common concerns in primary care and district hospitals where anaesthesia is commonly provided by generalist medical officers rather than dedicated anaesthetic practitioners. This article will allow revision for generalist doctors on the different types and indications for plexus, peripheral and local nerve blocks (see Table 1a and 1b for the different types of RA). We will briefly describe important principles of practice, informed consent, preparation of the patient and equipment and a few common techniques used in primary care emergency settings. Frequently, equipment such as nerve stimulators and ultrasound are lacking in district hospitals, resulting in a reliance on anatomical landmarks. Advocacy for ultrasound-guided RA, which can improve access to safe and reliable anaesthesia in low-resource countries as it becomes more user-friendly, durable and affordable, should remain a target.³ We discuss the properties and maximum doses of LA drugs that are used, as well as recognising symptoms and signs of toxicity when using these drugs. We briefly discuss a failed block and other potential complications that may occur.

Different types of regional anaesthesia used in theatre, emergency departments and for minor procedures (excluding neuraxial anaesthesia)

Important principles for good practice

When doing any anaesthetic, it is important to always be well prepared. Good preparation, good clinical practice and adherence to national guidelines will decrease the incidence and severity of common and predictable anaesthetic complications. Difficulty can arise in low-resource settings where a reliable supply of electricity, pulse oximeters and oxygen is often lacking. However, as a basic standard of care in an ED setting, standard monitoring and functional resuscitation equipment and drugs are required. The skills and equipment to convert to a GA if required should always be in place.⁷ Not all generalists are comfortable with converting to GA. Adequately trained providers are, however, essential, an ongoing challenge where there is a high turnover of staff and a lack of training and support. Valid informed consent must always be obtained from the patient, advising them on the most appropriate technique that will depend on patient characteristics and experience of the clinician. Risks and benefits of the proposed technique and alternatives should be discussed. In the theatre setting, patients must be aware that a GA may still be required if RA is used as an adjunct or if an incomplete block occurs. The patient should be provided with enough information, covering risks and benefits, complications, expected duration of action of the block, how to care for the insensate limb (particularly minor blocks seen in the ED that are discharged), red flags, the socioeconomic setting and when to return to the clinic or district hospital.⁷ As a general rule, there are no clear-cut indications for one type of anaesthesia over another when either would be appropriate. Absolute contraindications should be excluded, such as known allergy to drugs or patient refusal. Bleeding diathesis is a relative contraindication, especially if the block is performed in an area where compression is possible. Active infection at the site of injection, pre-existing neurological deficit and poor patient cooperation are further relative contraindications. Anti-coagulation therapy is not a contraindication if stopped within the minimum recommended time before the block is performed.⁷ Thorough documentation should be done. Resuscitation equipment must be immediately available, and intravenous (IV) access established before the procedure. The practitioner must ensure the block is fully established, vital signs and physiological parameters are within normal limits and the patient is stable.¹ Ensure an emergency trolley is immediately available for the management of complications and that the practitioner is skilled to rapidly recognise and treat these. Ensure appropriate measures are taken to minimise the risk of inadvertent nerve damage during the procedure. Always check and label drugs to be used to prevent error. In an ideal setting, a multidisciplinary team including nurses, doctors and clinical associates should work together to perform RA blocks. The team should be trained to prepare equipment and drugs, provide monitoring and have basic knowledge in evaluating the levels of pain and effects of RA.¹ In the chaos of busy district casualties, there needs to be guidance as to which patients are good candidates for RA and which patients are not.

Local anaesthetic agents and toxicity

Local anaesthetic drugs with or without adjuvants are used for RA. They are chosen according to their onset and duration of action, the degree of motor blockade and toxicity profiles. Lignocaine has a quick onset and short duration of action, and bupivacaine is longer acting.¹ Local anaesthetic drugs produce transient loss of sensory, motor and autonomic function when injected or applied in proximity to neuronal tissue. Although LA is relatively free from side effects, accidental IV injection or excessive dose can lead to toxicity. The central nervous system tends to be affected first (perioral numbness and tinnitus followed by seizures and coma), followed by the cardiovascular system (severe bradycardia and dysrhythmias).² Lipid emulsion (Intralipid) is used for bupivacaine toxicity, but is expensive, has a short half-life and is not readily available. Prolonged resuscitation may be required following bupivacaine toxicity. Cardiopulmonary resuscitation (CPR) should be continued for at least 60 min, as good neurological recovery can occur following LA systemic toxicity. The maximum dose of LA must not be exceeded.¹

• Potency depends on lipid solubility and the ability to penetrate membranes and determines the lower limit of the dose required for nerve blockade while toxicity sets the upper limit.
• Onset of action is determined by pKa (LA are weak bases), concentration of the drug, lipid solubility and the connective tissue surrounding the nerve (infected tissue or abscesses create an acidic environment that delays the onset of LA).
• Duration of action is determined by lipid solubility, protein binding, dose and site of injection (plexus blocks last longer than subcutaneous and intrathecal blocks).^2,8

Dosing example

• Using 2% plain lignocaine in a 50 kg patient:
  • 50 kg × 4 mg/kg   = 200 mg maximum dose          = 10 mL of 2% concentration
  • ADD 10 mL 0.9% NaCl = 20 mL of 1% concentration
  • ADD another 20 mL of 0.9% NaCl = 40 mL of 0.5% concentration.

A standard 2 mL dental cartridge (see Table 2)^7,8 of lignocaine in South Africa contains 36 mg of lignocaine.

Equipment and preparation for the procedure

Equipment will depend on the technique used. The correct needle monitors as per the American Society of Anaesthesiologists’ standards for basic anaesthetic monitoring (pulse oximetry, electrocardiogram [ECG], blood pressure [BP]), IV access for rescue medications and possible sedation and supplemental oxygen should be available. An emergency trolley including emergency drugs (e.g., adrenaline, atropine and lignocaine), anaesthetic drugs (e.g., suxamethonium, propofol and ketamine), along with airway and intubation equipment, should be readily available to treat RA-related complications. An aseptic technique must be used for all blocks (sterile gloves, masks and surgical drapes).¹

When performing a peripheral nerve block, the goal is to inject LA close to the nerve. Several methods have been used to identify the proximity of the needle to a nerve:

• Anatomical landmarks.
• Eliciting of paraesthesia caused by needle contact with the nerve.
• Electrical stimulation of a nerve without direct contact with the needle.
• Ultrasound-guided detection of the nerve.

In many public facilities at the district level in South Africa, nerve stimulators and ultrasound are not available, and there is a lack of training in the use of these techniques, and therefore, it will not be discussed in detail for the purpose of this article.

The role of ultrasound-guided RA is direct visualisation of the needle in relation to the nerve and other structures. Portable ultrasound machines are available, with high- and low-frequency probes, to identify both superficial and deep structures.¹

Anatomical landmarks, combined with ultrasound guidance, can be used simultaneously to improve the success rate of the block, decrease the onset of action of the block, reduce the volume of LA required and reduce the risk of vascular puncture.

Each technique may be associated with specific complications. The main complications of RA are block failure, nerve injury and LA toxicity. Local anaesthetic toxicity and allergic reactions to LA drugs occur very rarely.¹

When injecting LA, do not inject more than the maximum dose and be aware of the volume. Never inject under high pressure as the pressure effects could cause nerve damage. If there is pain or increased resistance, stop and reposition the needle. Always aspirate before injecting to avoid inadvertent injection into a vessel. If there is severe pain, stop and aspirate and the pain should stop immediately. You could be injecting directly into a nerve instead of around it. Allow 5 min – 10 min for maximal effect. Check on the sensory and motor effects depending on the block used. Warn the patient that they may feel numb for a few hours depending on the LA used.

Common blocks that can be used in the emergency departments and for minor procedures in district hospitals and clinics (see Table 3 for common limb blocks):

FIGURE 1: Digital nerve block.

FIGURE 2: Nerve distribution in the hand.

FIGURE 3: (a and b) Median and ulnar nerve blocks.

FIGURE 4: Radial nerve block.

Dorsal penile nerve block

Used for circumcision or reduction of a paraphimosis.

A dorsal penile nerve block is typically achieved through a ring block at the base of the penis or a dorsal penile nerve block at the level of the pubic symphysis or a combination of both. It is an effective technique for RA using small volumes of LA.¹³

For a dorsal penile nerve block, LA is injected into the bilateral spaces deep into the fascia on either side of the suspensory ligament. Insert a 25 G needle about 1 cm at the root of the penis on the dorsal aspect (at 01:30 and 11:30 positions) to penetrate Buck’s fascia and inject 5 mL on each side. Aspirate to prevent intravascular injection. Additional subcutaneous infiltration around the root of the penis (ring block) augments this block, as it covers cutaneous branches of the ilioinguinal and genitofemoral nerves. Always calculate the volume of anaesthetic required for circumcision in a child, which is much less.¹³ Never ever use adrenaline for penile blocks (Figure 5).¹³

FIGURE 5: Dorsal penile nerve block.

Conclusion

Safe RA is a useful clinical skill for district hospitals and clinics. It provides effective and often prolonged analgesia and improves patient satisfaction.³ Regional anaesthesia has wide application, with several nerve blocks that are easy to learn. Ultrasound-guided RA can broaden the scope, accessibility and safety of nerve blocks. Availability of context-sensitive guidelines and video demonstration should be made available in clinics and district hospitals.

Acknowledgements

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

M.T. conceived, drafted and reviewed the article.

This article followed all ethical standards for research without direct contact with human or animal subjects.

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data sharing is not applicable to this article as no new data were created or analysed in this study.

The views and opinions expressed in this article are those of the authors and are the product of professional research. It does not necessarily reflect the official policy or position of any affiliated institution, funder, agency or that of the publisher. The authors are responsible for this article’s results, findings and content.

References