Anesthesia

 

ANESTHESIA

Anesthesia is a state of narcosis (severe CNS depression produced by pharmacologic agents) used to produce unconsciousness, analgesia, muscle relaxation and reflex loss during surgical procedure.

            Anesthesia involves the use of medicines to block pain sensations (analgesia) during surgery and other medical procedures. Anesthesia also reduces many of your body  normal stress reaction to surgery.

TYPES OF ANESTHESIA .

The different types of anesthesia include the following.

1.      General anesthesia .

2.      Inhalation anesthetics.

3.      Intravenous anesthetics.

 

 

v  GENERAL ANESTHESIA .

The medication is either inhaled through a breathing mask or tube or administered through an intravenous line.

A breathing tube may be inserted into the windpipe to maintain proper breathing during surgery.

A combination of inhalation and intravenous anesthetics often with opioids added for pain relief and neuromuscular blockers for muscle paralysis is called balanced anesthesia.

v  INHALATION ANESTHETICS.

It is sometimes called volatile anesthetics or gas anesthetics.

All are administered with oxygen and usually with nitrous oxide as well.

v  INTRAVENOUS ANESTHETICS.

Administer with a cannula inserted into a vein ,usually in the patients forearm.

 

Other medicines that are often used during anesthesia include.

·         Muscle relaxants which block transmission of nerve impulses to the muscles.

·         They are used during anesthesia to temporarily relax muscle tone as needed.

·         Reversal agents which are gives to counteract or reverse the effects of other medicines such as muscle relaxants or sedatives given during anesthesia.

STAGES OF ANESTHESIA.

Classified into 4 stages.

v  Stage-I.

v  Stage –II or REM stage.

v  Stage –III or surgical anesthesia .

v  Stage –IV or over dose.

 

v  Stage-I.

 Begin with the induction of anesthesia and ends with the patients loss of  consciousness. The patient still feels pain in the stage I.

v  Stage –II

Includes uninhibited and sometime dangerous responses to stimuli, including ,vomiting and uncontrolled movement.

This stage is typically shortened by administering a barbiturate such as sodium pentothal before the anesthetic agent.

v  STAGE-III OR SURGICAL ANESTHESIA .

Is the stage in which the patients papillary gaze is central and the pupils constricted.

This is the target depth of surgical anesthesia. During this stage ,the skeletal muscles relax, the patients breathing become regular and eye movement stop.

 

v  Stage IV or overdose .

Is marked by hypotension or circulatory failure. Death may result if the patient cannot be received quickly.

 

 

         2 . LOCAL ANESTHESIA :

Is an anesthetic agent given to temporarily stop the sense of pain in a particular area of the body. For minor surgery a local anesthetic can be administered via injection to the site.

 

 

3.REGIONAL ANESTHESIA :

 It is a form of local anesthesia in which an anesthetic agent is injected around nervous so that the area supplied by these nerves is anesthetized. In this thype anesthetic agent block the transmission of nerve impulses in a particular area.

 

 

A.SPINAL ANESTHESIA:

It is a type of extensive conduction nerve block that occurs by introducing a local anesthetic agent into the subarachnoid space at the lumbar level, usually between L4 and L5 which surrounds the spinal cord. A spinal anesthesia is used for lower abdominal ,pelvic, rectal, perineum lower extremity surgery.

B. EPIDURAL ANESTHESIA :

Is achieved by injecting local anesthetic agent into the spinal canal in the space surrounding the Dura matter .  it is similar to a spinal anesthetic and is commonly used for surgery of the lower  limbs and during labor and child birth. This type of anesthesia involves continually infusing an anesthetic medication through a thin catheter (hollow tube).

 

The following are examples of other type of nerve blocks.

v  Brachial plexus block which produces anesthesia of arm.

v  Paravertebral anesthesia which produce anesthesia of nerve supplying the chest ,abdominal wall and extremities.

v  Trans sacral (caudal) block, which produces anesthesia of the perineum and occasionally.

    C.LOCAL NERVE INFILTRATION:

          It is achieved by injecting anesthetic agent around a local nerve to depress nerve sensation over a limited area of the body.

It is often administered in combination with epinephrine.

Epinephrine causes constriction of blood vessels which prevents rapid absorption of anesthetic agent and thus prolongs its local action.

A small gauge needle is used to inject a modest amount of the anesthetic into the skin layer. Anesthesia lasts any where from 45 min to 3 hours depending on the anesthetic and use of epinephrine.

SURFACE OR TOPICAL ANESTHESIA :

It is achieved by applying the anesthetic agent on the skin or mucous membrane to block nerve impulses at a particular site. Common anesthetic used are cocaine solution ,lidocaine and benzocaine.

THE NURSES ROLE DURING AND IMMEDIATELY AFTER SURGERY :

1.      Before surgery nurse has to check patients vital signs etc.

Get the patient ready for the surgery and help to prepare the sterile field for the surgery.

 

2.      During the operation nurse open supplies and pass them out, manage any tubes as drains and look after intravenous medication and solutions. The nurses make sure that nothing is left inside the patient after surgery.

3.      After surgery nurse check patients position as for patient with spinal anesthetic must lie flat . the patient monitoring equipment, IVS, drains and catheters are secured.

4.      Nurses keep a careful watch on the patients airway, breathing rate and depth and the color of the mucous membrane and nails beds. Nurse should to check B.P and TPR regular for patient .

5.      Patients wake up from the anesthesia and get back their reflexes at different speeds. To help them wake up the nurse can call their name and repeatedly tell them that the surgery is finished. As the vital signs stabilize and they begin to awaken , the nurse asks patients to take several deep breaths every five to ten minutes . patients position is changed every 10 to 15 minutes.