Regional Aneasthesia

Regional Aneasthesia

CHOICE
Choice of a local anaesthetic technique depends upon its
feasibility for a particular procedure and
the patient’s willingness and
ability to co-operate, as well
the surgeon’s and
anaesthetist’s preference

For minor procedures

Local anaesthesia may be the reliable and traditional method for some minor surgical procedures which do not warrant general anaesthesia.

Advantages& disadvantages

One of the main advantages is the continuation of pain relief into the postoperative period, by either drugs with a prolonged duration of action or delivery of further local anaesthetic increments via a catheter.
However, local anaesthesia is not infallible, and may be contraindicated by allergy or local infection. Epidural and intrathecal anaesthesia includes sympathetic blockade which may result in vasodilatation and systemic hypotension, and may confer greater intraoperative risk than a carefully managed general anaesthetic.

Complications

Complications may be
local, such as infection or haematoma, or
systemic if overdosage or
accidental intravascular injection leads to toxic blood levels


Over dose
may manifest as depressed conscious level, convulsions and/or cardiac arrest (particularly bupivacaine), and
may be heralded by circum-oral paraesthesia and light-headedness
Recently introduced local anaesthetics such as ropivicaine and laevobupivacaine are claimed to have enhanced safety profiles

Adrinaline with local anesthetics

Addition of adrenaline (commonly 1:200000-1:125000 concentration) to the local anaesthetic solution
hastens the onset and
prolongs the duration of action, and
permits a higher dose of drug to be used as it is more slowly absorbed into the circulation.

Contraindication to adrenaline with local anesthetics

hypertensive patients, IHD, cardiac dysrrhythemies or for patients taking either monoamine oxidase inhibitor or tricyclic antidepressant drugs, as its cardiovascular effects are potentiated.

Contraindication to adrenaline with local anesthetics

Addition of adrenaline to the local anaesthetic solution increases the risk of cardiac arrhythmia associated with accidental intravascular injection.
It should not be used in end arterial locations, where there is no collateral circulation, such as ear, penis, fingers, and toes, or around the retinal artery.

Important

The potential risk of life threatening sequelae mandates the availability of appropriately skilled personnel and resuscitation equipment including oxygen, as prerequisites if local anaesthesia is practised


Methods of giving LA
Topical anaesthetic
Local infiltration
NERVE BLOCK
Regional anaesthesia (without general anaesthesia)
Regional anaesthesia (with general anaesthesia

Topical anaesthesia

Topical anaesthetic agents are used on the skin, the urethral mucosa, nasal mucosa and the cornea.
The agents used are amethocaine, because it is well absorbed by mucosa, cocaine for its vasoconstrictive properties, lignocaine and prilocatne.
A lignocaine and prilocaine eutectic mixture ( ‘ EMLA ’ cream) is commonly used on the skin of children before venepuncture.

Local infiltration

most commonly used method
. It is not necessary to starve the patient preoperatively unless the procedure carries a high risk of intravascular or intrathecal injection.
Infiltration of local anaesthetic drug may be into or around a wound, ideally with particular attention to neuroanatomical territories and boundaries.
Contraindications are local infection and clotting disorder.
Not only local infiltration will spread the infection, but local anaesthetic drugs are ineffective in conditions of acidity as produced by infection. Local infiltration in the presence of a clotting disorder may result in haemorrhage, or may produce haematoma, potentially fatal in the airway, as in dentistry.

Regional anaesthesia (without general anaesthesia)

involves blockade of major nerve trunks which innervate the site of surgery. It is usually performed by an anaesthetist with the necessary skills. However, both intrathecal (spinal) and epidural anaesthesia should only be con­ducted by experienced practitioners using full aseptic techniques.


Regional aneasthesia
Its required that a doctor other than the operator is present to monitor continuously and resuscitate the patient if necessary. If regional anaesthesia fails, general anaesthesia may be necessary. Compensation for an inadequate regional block by heavy sedation carries great dangers including airway obstruction and pulmonary aspiration of gastric contents. These may easily go unrecognised by a single-handed operator.

RA
All patients should be starved preoperatively & monitored.
In emergency surgery, R A.carries the advantage of preservation of the protective laryngeal reflexes, particularly in emergency obstetric anaesthesia, for which epidural or spinal regional anaesthesia is commonly the method of choice.

RA
The reduction in blood pressure with spinal and epidural anaesthesia can be advantageous in reducing intraoperative blood loss, but only if the surgeon strives to achieve haemostasis prior to wound closure and restoration of normal blood pressure.
When sedation has been used for surgery under regional anaesthesia, respiratory obstruction may occur postopera­tively when the surgical stimulus has ceased.

RA
. Oxygen saturation measurement by pulse oximetry & blood pressure monitoring is required during regional anesthesia.
Regional anesthesia had a very clear advantage for patients who have debilitating respiratory disease.

RA
The most clear indications for spinal and epidural anaesthesia are in obstetric practice to spare the mother from the risk of pulmonary aspiration because of the full stomach usually present in labour, and
also to spare the newborn from the depressant action of the general anaesthetic and analgesic drugs.

General and regional anaesthesia combined

Combining the two methods of anaesthesia in well-balanced measure enables a patient to receive a lighter general anaesthetic and to have the advantage of good postoperative analgesia.
At its simplest, the infiltration of an abdominal wound with local anaesthetic agent will facilitate comfortable breathing in the recovery room.


STARVATION PRE OP.
In elective cases must be.
In emergency LA carry less risk than GA .
risk of aspiration of gastric contents is much reduced although not absent

Heparin

subcutaneous low-molecular-weight heparins (LMWH) for prophylaxis for deep venous thrombosis are longer acting than heparin, and
appear to have increased the risk of intraspinal haematoma.
Epidural and spinal injections (and catheter insertion or removal) should only be performed at least 12 hours after a LMWH dose, and the next LMWH dose delayed for at least 2 hours. The LMWH doses must therefore be timed appropriately

Monitoring

Electrocardiogram, pulse oximetry and blood pressure measurements should be performed during regional anaesthesia. Oxygen by face mask should be given to frail or sedated patients during surgery.

Common local anaesthetic techniques

In awake patients the nerve blocks must provide comprehensive numbness throughout the surgical field. The following field blocks are commonly used.
1• Brachial plexus block for surgery on the arm or hand.
2• Field block for inguinal hernia repair. The iliohypogastric and ilioinguinal nerves are blocked immediately infero­medial to the anterior superior iliac spine. The genito­femoral nerve is infiltrated at the midinguinal point and at the pubic tubercle. If a large volume of local anaesthetic is used, the peritoneal sac can be anaesthetised before the incision, but care must be taken to avoid drug toxicity. Adrinaline can be added ,the line of the skin incision should be infiltrated with the mixture.
3• Regional block of the ankle. This can be used for surgery on the toes and minor surgery of the foot.



Intravenous regional anaesthesia

The arm to be operated on is exsanguinated by elevation and/or compression, and then isolated from the general circulation by the application of a tourniquet inflated to a pressure well in excess of the systolic. arterial pressure. The venous system is then filled with local anaesthetic agent, injected via a previously placed indwelling venous cannula. The drug diffuses from the bloodstream into the nerves to produce an effective block. The arm is more suitable for this procedure (Bier’s block) than the leg because the large volume of drug required for the latter can easily lead to toxicity. (1)The tourniquet must only be deflated after adequate time has elapsed

Intravenous regional anaesthesia

(at least 20 minutes) to allow for the residual venous drug load to fall to a safe level, before it is washed back into the general circulation.
Cardiac arrest or convulsions may well occur if the tourniquet is accidentally released before the drug is fixed; this was particularly noted with bupivacaine, which has been banned from use in this procedure after reports both of a number of deaths and of directly toxic effects on the heart. Prilocaine or licnocaine 0.5 % up to 20ml in arm and 50ml for leg
Prilocaine is recommended as the safest agent to use.
As above, a separate medical practitioner should supervise the block and monitor the patient, while the surgeon operates.

Neuroaxial aneasthesia

lntrathecal anaesthesia
Epidural anaesthesia

lntrathecal anaesthesia

Spinal anaesthesia in the awake patient is useful for some forms of surgery in the pelvis or lower limbs.
Hyperbaric solutions of lignocaine or bupivacaine are injected as a ‘ single shot ’ into the cerebrospinal fluid, to produce rapidly an intense blockade, usually within 2-5 minutes.

Hypotensiun

Autonomic sympathetic blockade results in hypotension,
Prevention by prior intravenous fluid loading and titration of vasoconstrictor drugs.
If the hypobaric solution is allowed to ascend too high, severe hypotension and ventilatory failure occur. This factor limits the use of spinal anaesthesia to surgery below the segmental level of T5.


Headache
Postoperative headache, due to cerebrospinal fluid leakage through the dural perforation, is nowadays much less common as a result of modern needles (very fine with a round or pencil point tip and side aperture) designed to split rather than cut the dural fibres.

BEST INDICATION

Spinal anaesthesia is much used for Caesarean section, prostatectomy and lower limb surgery. Intrathecal opioid drugs are used to produce postoperative analgesia but there is a significant risk of respiratory depression.

Epidural anaesthesia

Epidural anaesthesia is slower in onset than intrathecal anaesthesia, but has the advantage of multiple dosing and hence prolonged use, as an indwelling catheter may be threaded into the epidural space. Hence, epidural anaesthesia can provide good pain relief extending into the postoperative period.
Urinary retention is common, necessitating catheterisation of the bladder.
Epidural anaesthesia also includes sympathetic blockade, but it is of slower onset, as is the resulting hypotension, which may be easier to control and can be used to advantage for the surgery, in reduction of blood loss.
If a weak solution of bupivacaine or the newer ropivicaine is chosen, epidural anaesthesia can be used to produce a predominantly sensory block for analgesia after upper abdominal or thoracic surgery.

LA +OPIOID

combine weak solutions of local anaesthetic with opioid agents such as the lipid-soluble diamorphine or fentanyl,they producing analgesia by their action on the opioid receptors in the spinal cord.
However, the potential complication of epidural opioid analgesia is delayed respiratory arrest from rostral spread and central depression, as late as 24 hours after the last dose. Hence, regular monitoring of conscious level and respiratory rate, and facility to immediately reverse the opioid with intravenous naloxone or to resuscitate, are essential prerequisites.

LA&OPIOID

Epidural anaesthesia (with bupivacaine or ropivicaine) remains the standard method of anaesthesia during painless labour and interventional delivery.
In contrast to local anaesthetic agents, epidural opioid agents alone do not produce hypotension, so they are preferable for patients who are mobile.
There is a current trend towards their use in labour for this reason, but alone they would not produce adequate analgesia for surgical intervention.


Caudal epidural anaesthesia
It is produced by injection of local anaesthetic agent through the sacrococcygeal membrane.
Its main uses are to supplement general anaesthesia and for very effective postoperative pain relief.
This analgesic technique is much used in paediatric surgery

Perioperative pain relief (acute pain management)

Optimal management of acute postoperative pain requires planning, patient and staff education, and tailoring to the type of surgery and the needs of the individual patient.
Patients vary greatly (up to eight-fold) in their requirement for analgesia, even after identical surgical procedures.

Post op analgeisa

Under-treatment results in unacceptable levels of pain with tachycardia, hypertension, vasoconstriction and ‘ splinting ’ of the affected part. Painful abdominal and thoracic wounds restrict inspiration, leading to tachypnoea, small tidal volumes, and inhibition of the patient from effective coughing and mobilisation.
This predisposes to chest infection, delayed mobilisation, deep venous thrombosis, muscle wasting and pressure sores.

Post op. analgesia

analgesic administration above the patient’s requirement increases the risks of side effects such as nausea, vomiting, somnolence and dizziness or, if greatly in excess, severe central effects including depressed consciousness and respiration.
This is fortunately rare, and can be avoided by sensible initial dosing followed by titration until the patient is comfortable.

Post op. analgesia

Exaggerated fears of opioid induced central depression and addiction have led all too commonly to inhibition amongst staff from prescribing and administering adequate doses of opioids.
Intermittent intramuscular dosing also leads to delays in administration of the ‘ controlled ’ opioids compounded by the time to onset of action. As a result of these common deficiencies,


Post op. analgesia
Combinations of analgesic methods [local anaesthesia and nonsteroidal anti-inflammatory drugs (NSAIDs) with opioid drugs] were advocated, as were the more sophisticated methods of pain management such as ‘ patient-controlled analgesia

Combinations of analgesia

•local anaesthetic blocks — excellent short-term analgesia, but requires skill and has a small failure rate. Continuous catheter techniques prolong pain relief but are only appropriate for inpatients;
•spinal opioids — generally very useful for appropriate types of surgery, but again requires skill, and is limited by concerns over severe respiratory depression;
•NSAIDs — in combination reduce requirement for opioids and alone are useful for moderate pain, but are limited by concerns over side effects, such as renal impairment, peptic ulceration and inducing acute bronchospasm in asthmatics. They are not adequate as sole analgesic therapy after major surgery.

Combinations of analgesia

clonidine has been administered epidurally to stimulate the spinal cord adrenergic inhibitory mechanisms.

Severe acute pain increases morbidity after trauma or surgery. Appreciation of pain pathways and the three main classes of pain — nociceptive, neuropathic/sympathetic and that of mainly psychological origin — together with enhanced awareness of pain, has led to new and multimodal treatment strategies

The methods of prevention

1•adequate analgesia by intravenous narcotic drugs at the time of surgery;
2•regional anaesthesia alone or supplementing general anaesthesia during surgery to prevent excitation of central pathways;
3 •the use of prostaglandin inhibitory drugs during surgery. Diclofenac suppositories are effective in reducing the pain from tissue damage in bone and muscle, and are used at the time of operation. These three approaches used together are good at preventing the cycle of pain and muscle spasm from becoming established in the recovery period. The same methods can be used for managing the pain of acute trauma.

Postoperative pain management

Severe pain from a large incision in a frail patient may require high doses of intravenous opiate drugs leading to elective postoperative endotracheal intubation and ventilation until the patient is stable.
This approach should be used if the patient is likely to become hypoxic through struggling in pain if other methods of pain relief are not effective. Other methods of pain relief, properly used, can usually prevent the need for mechanical ventilation even in very major thoracic and abdominal surgery.


Acute pain relief teams, using continuous methods of pain relief in high dependency areas well equipped with monitoring, are becoming a routine feature of the postoperative care in both the USA and the UK.
Regular intramuscular morphine injection, supplemented by anti-inflammatory analgesic drugs and, possibly, a regional anaesthetic block, are effective treatment for the majority of surgical patients.

Each patient should have a pain relief measurement chart for regular assessment with other routine nursing observations.

Special methods of pain relief used under close supervision

• 1- continuous epidural anaesthesia with opiate or local anaesthetic drugs;
2• continuous intravenous opiate analgesia;
3• patient controlled analgesia by injection intravenously or epidurally of opioid analgesia. The patient is trained to give a bolus dose of drug by pressing a control button on a machine whose functions have been regulated by the medical staff. The strength, frequency and total dose of drug in a given time are all limited by computer.
Effective postoperative pain relief encourages early mobilisation and hospital discharge.

minor surgeries

In minor surgery, and when the patient is able to eat after major surgery, aspirin and paracetamol are often the only drugs necessary to control pain.
Fear of metabolic acidosis and Reye ’ s syndrome of hepatotoxicity in children have made paracetamol a preferable drug to aspirin in the younger age group.
Patients with a tendency to peptic ulceration may need cover with omeprazole or misoprostol during analgesic treatment with anti-inflammatory agents
Codeine phosphate is the analgesic favored after intracranial surgery because it does not have a powerful respiratory depressant effect; it may never be given intra­venously as it causes profound hypotension on intravenous injection.
.