**4. Commonly used recipes in clinical practice**

#### **1. Spinal anaesthesia (SA) for caesarean delivery**

The ideal subarachnoid dose of local anaesthesia for caesarean delivery has been debated for a long time. Most anaesthetists employ hyperbaric 0.5% bupivacaine in a dose of 7.5–15.0 mg. A meta‐analysis suggests any reduction in the bupivacaine dose during single‐shot SA to less than 8 mg with opioid or 10 mg alone, resulting in a significantly increased requirement for analgesic supplementation and possibly conversion to general anaesthesia [40]. The practice at our insti‐ tution is to use 10 mg of hyperbaric bupivacaine plus 10 μg fentanyl with satisfactory results.

#### **2. Labour epidural analgesia**

**2. Alpha‐2 adrenoceptor agonists**

16 Current Topics in Anesthesiology

anaesthesia [37].

**4. Other adjuvants**

improvement in analgesia.

clonidine for peripheral nerve and plexus blocks [36].

reports regarding the use of adrenaline in lumbar epidurals.

epine premedication prior to block reduces the risk of these side effects.

nesium has been reported to produce transient neurological toxicity.

**4. Commonly used recipes in clinical practice**

**1. Spinal anaesthesia (SA) for caesarean delivery**

**3.** *N***‐methyl‐d‐aspartate receptor antagonists**

**Clonidine**: intrathecal use of clonidine as an adjunct to local anaesthetics prolongs the dura‐ tion of sensory blockade by approximately 1 h [35]. However, the duration of motor block‐ ade is increased, and the incidence of hypotension is also high. The recommended dose for intrathecal use is in the range of 15–150 μg with the incidence of adverse effects (bradycardia, sedation, hypotension) increasing with doses above 150 μg. In paediatric anaesthesia, the use of clonidine (1 mg/kg) for caudal blocks doubles the duration of analgesia when compared to LA alone, but causes sedation. Further research is needed to examine the benefits of using

**Dexmedetomidine** is a highly selective alpha‐2 adrenoceptor agonist. There is some evidence to suggest a clinical benefit to use of dexmedetomidine with LA for intravenous regional

**Adrenaline** has direct and indirect actions as an adjuvant. It acts directly on α‐2 adrenocep‐ tors in the substantia gelatinosa of the dorsal horn of the spinal cord resulting in presynaptic inhibition of transmitter release from C and Aδ fibres. Indirectly, it causes local vasculature constriction thus prolonging the duration of action of the LA. Adrenaline used as an adjunct to thoracic epidural infusions improves the quality of analgesia [38, 39]. There are conflicting

**Ketamine**: preservative‐free ketamine injected into the caudal epidural space for children at a dose of 0.5 mg/kg has been shown to extend analgesia time by several hours. The opponents of ketamine cite increased the risk of psychotomimetic side effects, but the use of benzodiaz‐

**Magnesium**: intrathecal or epidural magnesium has been used with variable results. It may prolong LA/opioid block in women in labour at a dose of 50 mg, but a very high dose of mag‐

Other adjuvants like midazolam and neostigmine have been suggested to improve the quality of analgesia. However, the high incidence of significant side effects far outweighs the small

The ideal subarachnoid dose of local anaesthesia for caesarean delivery has been debated for a long time. Most anaesthetists employ hyperbaric 0.5% bupivacaine in a dose of 7.5–15.0 mg. A meta‐analysis suggests any reduction in the bupivacaine dose during single‐shot SA to less than 8 mg with opioid or 10 mg alone, resulting in a significantly increased requirement for analgesic The current policy at our institution is to draw up a mixture of 5 mL of 0.5% bupivacaine, 4 mL saline and 50 μg fentanyl, that is, a total of 10 mL of 0.25% bupivacaine with 5 μg/mL fentanyl, and to administer two 4 mL boluses of this mixture 3 min apart, with the patient in the left lateral position for the first bolus and the right lateral for the second. In early labour, an initial bolus of 8 mL of 0.125% bupivacaine may be given, followed by a repeat dose of a similar volume. The aim is to obtain levels of T8–T10 bilaterally, and this can take up to 20 min. Analgesia is main‐ tained with an infusion of 0.125% bupivacaine plus 2 μg/mL fentanyl at the rate of 8–14 mL/h.

#### **Top‐up of labour epidural for caesarean delivery step‐by‐step**


#### **3. Local anaesthetics for regional intravenous anaesthesia**

Regional intravenous anaesthesia is indicated for short operative procedures for extremities and sometimes for pain therapy (e.g. treatment of complex regional pain syndromes). This is a very basic technique, and it requires 12–15 mL of 2% lidocaine or 30–40 mL of 0.5% lidocaine for upper extremity regional anaesthesia. Other local anaesthetics such as bupivacaine are contraindicated for IV injection for reasons discussed in the toxicity section. Some evidence exits supporting a better quality of the block by use if additives such as ketamine and alpha‐2 agonists are added to local anaesthetics for peripheral nerve blocks [41, 42].

Equipment required includes:


#### Technique:


#### **4. Local anaesthetics for peripheral nerve blocks**

There are a wide variety of local anaesthetic agents available for peripheral nerve blocks. Important points to consider when making the choice are onset and duration of action, dura‐ tion of the surgical procedure and anticipated degree of pain. Caution is to be used if one decided to use additives to local anaesthetics for peripheral nerve blocks to prolong their effect as none of the additives discussed in this chapter have got the Food and Drug Administration (FDA) approval for this purpose [43].

#### **5. Topical anaesthetics**

Topical anaesthetics are used for procedures such as vein cannulation, laceration repair to avoid infiltrative local anaesthesia injections and associated pain. They are widely used in the paediatric population. There are many dosage forms in clinical use, for example, gels, sprays, creams, ointments, patches. Skin absorption is variable and accounts for the systemic toxicity. This complication is rare provided the skin is intact with the exception of 5% EMLA cream, a eutectic mixture of 2.5% lidocaine and 2.5% prilocaine. Commonly available forms are Ametop (4% tetracaine) and EMLA, and more recently, a 4% lidocaine topical cream has been introduced. It is better tolerated on the skin while having flexible application times. Onset of action for Ametop is between 30 and 40 min and has a duration of action of about 4–5 h. EMLA on the other hand has a slower onset of about 60 min with a short duration of action of about 2 h. Toxicity is largely related to the age of the patients and possible damage in the skin. It is recommended that in those below 3 months, duration of application should not be more than 1 h, while for age group between 3 and 12 months maximum duration of application does not exceed 4 h [44].

#### **6. Neuraxial techniques in paediatrics**

Caudal anaesthesia is a popular technique to provide analgesia in paediatric patients. The sin‐ gle‐shot technique is often adequate for most urological, lower extremity and lower abdomi‐ nal procedures. An indwelling catheter can extend its use to upper abdomen and thoracic procedures and offers the added benefit of continuous post‐operative analgesia. The LA dose depends on the operative site that ranges from 0.5 to 2 mL/kg of 0.25% bupivacaine, that is, the level of the block is proportional to the dose.

Spinal and epidural anaesthesia are safe and effective ways to provide anaesthesia for infants [45]. For spinal anaesthesia, bupivacaine 0.5% at a dose 0.5–1 mg/kg is commonly used with the dose decreasing with increasing age.

Local anaesthetics add to the armament that is at the disposal of anaesthetists. Understanding of their pharmacology increases the safety with which these drugs can be used. Early recog‐ nition of toxicity is core to avoiding central nervous system and cardiorespiratory collapse.
