May 31, 2023
Local or regional anesthesia is given only to the applied region, and in this the patient is fully conscious. For the case of a person with injury in the femur/inguinal hernia/ umbilical hernia, spinal anesthesia is given to the person.
Scale up your NEET PG preparation with this blog on important topics for Anesthesia and experience the best NEET-PG coaching available online.
Layers which are pierced during the administration of the central block are:
Spinal cord → Pia mater → arachnoid mater → dura mater → ligamentum flavum → supra and interspinous ligament → subcutaneous fascia → skin
Between the pia mater and arachnoid mater there is a space known as Subarachnoid space and Between the dura mater and arachnoid mater there is a space known as Subdural space.
From outside to inside,layers are present as skin, subcutaneous fascia, supra and interspinous ligament, ligamentum flavum, dura mater, arachnoid mater, pia mater, and spinal cord. Subarachnoid space contains CSF, whereas Epidural space (outside dura mater) is an air-containing cavity.
Subarachnoid anesthesia is also called spinal anesthesia (giving the drug in the CSF), and epidural anesthesia (air-containing cavity) is also known as extradural anesthesia.
The difference between spinal and extradural anesthesia is given below:
|Subarachnoid / spinal anesthesia||Epidural / extradural anesthesia|
|Drug given is at the level of L2-L5||Extradural space|
|Fast onset because the drug mixes with CSF||Delayed effect There is no carrier fluid|
|Easy to control the level of the drug with positioning of the patient (drug is hyperbaric) Mixed with dextrose||1.5-2 ml/ segment To achieve that level of the drug.|
|More haemodynamic imbalance||Less haemodynamic imbalance|
|Easily confirmed with return of CSF||Confirmed with loss of resistance. It require practice|
|Intraoperative use||Since we put an epidural catheter the duration of surgery can be prolonged and can be used for post-op analgesia as well|
18 and 16 gaze
S/e- mc complication - hypotension
Does not increase HR
Use in pregnancy
In pregnancy, an epidural catheter in epidural space can produce analgesia without giving anesthesia by titrating a dose of local anesthetic. The sensory pathway is blocked, but the motor pathway is normal. Its Composition is Bupivacaine 0.125% + Fentanyl.
Local anesthesia is the condition where there is reversible loss of sensation which is circumscribed to an area by decreasing excitation nerve ending by decreasing conduction. They act by blocking Na+ channels. They consist of aromatic and amino groups which are attached by ester and amide bonds. An active nerve fiber is the best state of a nerve for maximum action of local anesthetic. Systemic absorption:
Intravenous (best) > tracheal > intercostal > paracervical < caudal > lumbar > brachial plexus > sciatic > subcutaneous
Different Types of Nerve Fibers are given below :
|Different types of Nerve Fibers|
|A β||Touch, Pressure via Touch|
|A γ||Afferent Muscle Spindles|
|A δ||Fast Pain and Temperature|
|C||Slow Pain, Post Ganglionic|
When a local anesthetic is combined with vasoconstrictor, constriction of vessels and hence less absorption.
|Increased duration of drug action||Painful on injection|
|Increased Intensity of action of drug||Tissue edema|
|Decrease systemic toxicity||Necrosis|
|Decrease blood loss|
It consists of ester and amide groups. Chloroprocaine is the shortest acting. The most widely used are lignocaine, bupivacaine and ropivacaine.
|Ester (i)||Duration||Amides (ii)||Duration|
|Cocaine||Short acting||Lignocaine||Intermediate acting|
|Procaine||Short acting||Mepivacaine||Intermediate acting|
|Chloroprocaine||Shortest acting||Prilocaine||Intermediate acting|
|Benzocaine||Long acting||Bupivacaine||Long acting|
|Tetracaine||Long acting||Ropivacaine||Long acting|
Toxicity is highly dangerous, and a scale is present to measure the toxic level called LAST. Symptoms of toxicity include Anxiety, tinnitus, seizures, arrhythmia, and cardiac arrest.
To scale up your NEET PG preparation with the best-in-class video lectures, QBank, Mock Tests and more, download the PrepLadder App!
Download PrepLadder's NEET PG preparation app for Android
Download PrepLadder's NEET PG preparation app for iOS
Get access to all the essential resources required to ace your medical exam Preparation. Stay updated with the latest news and developments in the medical exam, improve your Medical Exam preparation, and turn your dreams into a reality!
The most popular search terms used by aspirants