presented by: Pratima Sharma

TYPES OF ANESTHESIA

What is anesthesia ?

It is defined as a pharmacologically induced and reversible state of amnesia, analgesia , loss of responsiveness , loss of skeletal muscle reflexes or decreased stress response or all simultaneously.

Why we need anesthesia?

PAIN……

It is an unpleasant sensory and emotional experience associated with actual or potential tissue damage

It is most common reason for doctor consultation; it is a major symptom in many conditions & can significantly interfere with patient’s quality of life and general functioning.

Anesthesia,thus, helps in reducing the pain

temporarily for various treatment procedures to be carried out smoothly and successfully.

Anesthesia can be classified broadly as:

General Anesthesia. Local Anesthesia.

GENERAL ANESTHESIA

It means complete loss of consciousness, loss of pain and muscle relaxation.

It is given when patient has to be unconscious and immobile. e.g. maxillofacial surgeries.

Depending on drugs used to produce GA,it can be:

1. Inhalational anesthesia- where we use inhalational agents like halothane, isoflurane etc.

2. Intravenous anesthesia- where onlyn IV drugs are used like thiopentone, ketamine, propofol etc.

But before giving GA, a proper pre-anesthetic check up is must.

PRE-ANESTHETIC ASSESSMENT: In this we cover: 1. Relevant information about the patient’s

medical history,physical & mental conditions. 2. To obtain an informed consent. 3. To educate the patient about anesthesia, pre-

operative care & pain treatment for reducing anxiety & facilitating recovery.

Also, general physical examination, routine & specific investigations alongwith airway assessment should be done.

In airway assessment we look for loose artificial dentures,mobility of neck, external trauma, nostril size & patency, jaw malformations, mouth opening.

After pre-operative assessment, patients are prepared before surgery. If any medical problem persists,appropriate treatment is instituted.

After this preliminary assessment, in non-emergency cases patients are advised to keep fasting for atleast 6hrs,empty bladder & bowel, remove artificial dentures & ornaments.

Pre-Anesthetic Medication

It is administered 1-2hrs before surgery depending on the route of administration.

Aims of premedication are: - Reduction of fear & anxiety. - Reduction of saliva secretion. - Prevention of vagal stimulation. - To produce amnesia. - For specific therapeutic effects-e.g.

antiemetics,H2 blockers.- For pain relief in painful conditions e.g

fractures.

Drugs used for Premedication:

Sedatives- barbiturates, BZDs, phenothiazines. Analgesics- narcotics like morphine,pethidine

or long acting NSAIDS e.g ketoprofen. Neuroleptics- e.g opiods. Anticholinergics- Atropine,glycopyrrolate. Oral antacids- H2 blockers.Timings for pre-medication is very

important;If given too late- watch should be kept for

possible respiratory depression after induction.If given too early- If >3hrs delay,atropine is to

be repeated IV if vagal blockade is required.

There are 3 phases during successful anesthetic delievery:

INDUCTION. MAINTENANCE. RECOVERY.

Induction Of GA:

Depending upon drugs used there are 2 types of induction techniques:

1.) Inhalational Induction: It is achieved using gases & anesthetic vapours,the partial pressure of these agents exerted in the brain determines depth of anesthesia.

Usually a mixture of N2O & O2 is used alongwith vapours like halothane,isoflurane. But in poor risk patients, O2 alone can be used alongwith vapours.

Indications:

Small uncooperative patients. A compromised air-way due to tumors. Where IV drugs are contraindicated. Restricted or immobile jaw.TECHNIQUE: patient is breathed with 2:1 mixture of N2O &

O2 & then vapour is added, gradually increasing the percentage until required level of anesthesia is reached. Patient is then maintained on inhalation agent by mask or endotracheal intubation with O2 & N2O as carrier gases.

In cases like pregnancy or patients with poor cardio-respiratory reserve, pre-oxygenation with 100% O2 for 5 min before induction helps to wash out N2 off the lungs & also helps to tide over any hypoxic insult that can occur during induction.

2.) Intravenous Induction:

Most preferred method because induction is rapid,smooth & pleasant.

Commonly used drugs include thiopentone sodium, ketamine,propofol etc.

These conditions are specifically indicated in: - Gastric regurgitation & aspiration problem. - In non-fasting patients - Head injury & other trauma vitims. - Diabetic & uremic patients. - Pregnant patients. - Patients with reflux disease.

Thiopentone is most common drug available & in use. Patient is ventilated with 100% O2 preferably before induction for 5min & then anesthetic is injected.

Once anesthesia is induced

depending upon circumstances, airway may have to be maintained by putting an ENDOTRACHEAL TUBE.

Endotracheal Intubation(ETI) Airway maintenance is foremost indication of

ETI especially after introduction of skeletal muscle relaxants which makes controlled ventilation mandatory.

INDICATIONS: 1. Head & neck surgeries. 2.To maintain a clear airway in difficult

circumstances, e.g unconscious patients. 3. To prevent contamination of ENT. 4. Prolonged artificial ventilation in all major

surgeries & respiratory care; to maintain adequate oxygenation also.

Instruments required include Laryngoscope with all size blades, proper size endotracheal tubes, magill’s forceps, stylets & mouth gag etc.

Types of ETI are: - Nasal: guided under anesthesia. - Oral: guided under anesthesia with

laryngoscope.

Stages of GA :

These were based on a progressive increase of muscular paralysis(eye-ball muscles,inter- costals, diaphragm) & a progressive abolition of reflex response.

STAGE 1- (stage of analgesia) characterised by analgesia from the

beginning of induction. Patient experiences disorientation; respiration is quiet but often irregular. As consciousness & eyelash reflex are lost, patient passes onto next stage.

STAGE 2(stage of excitement or delirium):

It lasts from loss of consciousness to the onset of surgical anesthesia.

Patient gradually becomes unconscious but all reflexes are intact; at times patient is uncooperative & violent.

To avoid vagal stimulation at this stage patient is pre-medicated with atropine.

The eyelid reflex disappears when patient goes from stage 2 to 3.

STAGE 3( stage of surgical anesthesia)

This stage is commonly divided into 4 planes: a.) Plane 1: respiration becomes irregular,

movements of extremities stop; eyelid reflex is lost; eyeballs movements are incoordinated conjuctival reflex lost; laryngeal reflex intact however pharyngeal reflex is lost.

b.) Plane 2: eyes become centrally fixed; pupils are constricted; laryngeal reflex lost; muscle tone decreased but respiratory muscles are functioning.

c.) Plane 3:

Pupillary light reflex lost; muscle relaxation with onset of paralysis of intercostal muscles. Repiration is largely diaphragmatic.

d.) Plane 4: respiration gradually becomes depressed; increase in diaphragmatic paralysis.

STAGE 4: (stage of medullary paralysis) This stage is possible by overdosage of

anesthetic drug; respiration is gasping & finally arrested; pupils are widely dilated; BP is very low & pulse is feeble.

MAINTENANCE OF GA

Once anesthesia is induced & endotracheal intubation is done, it has to be maintained till the end of surgical procedure.

All the requirements of GA i.e. hypnosis, analgesia & muscle relaxation should be met during maintenance period.

WITHDRAWAL OF ANESTHESIA Extubation: performed when patient is deeply

anesthetised or nearly fully awake; deep or anesthetised extubation is performed only after muscle relaxants have been fully reversed & patient is maintaining an acceptable respiratory rate & depth.

Reversal: It is antagonisation of the muscle relaxation produced by non-depolarising relaxants using specific drugs.e.g. anticholine esterase like neostigmine, edrophonium etc.

- Clinical signs of adequate reversal are judged by various tests to assess the motor power & neuro muscular function like sustained head lift for >5 sec considered most reliable

- Failure to breath after reversal may be caused by low CO2 levels, opioid depression, breath holding etc.

Recovery: It is the period from cessation of anesthesia until patient is awake & regained protective reflexes.

- complications encountered during extubation & recovery phase are airway obstruction, laryngospasm, aspiration, pharyngitis & laryngitis, laryngeal oedema & stridor.

LOCAL ANESTHESIA

It has been defined as a loss of sensation in circumscribed area of the body caused by a depression of excitation in nerve endings or an inhibition of the conduction process in peripheral nerves.

Classification of LA:

There are 2 types of LA: 1.) Esters esters of benzoic

acid esters of

paraamino benzoic acid

2.) Amides

3.) Quinoline

LA can also be classified as:

Low potency,short duration: e.g procaine, chloroprocaine.

Intermediate potency & duration: e.g lignocaine, prilocaine.

High potency, long duration: e.g tetracaine, bupivacaine, ropivacaine etc.

Indications

To reduce anxiety and pain during dental procedure.

Any procedure requiring localized, short-term anesthesia, including a broad range of medical and minor surgical procedures.

Can be used as an anti-arrhythmic drug.

Helpful in treating refractory cases of status epilepticus.

Contraindications

The presence of inflammation/infection.

The presence of acute tissue injury. Bleeding disorder. Reported allergy to the solution. Liver disease Pseudocholinestrase deficiency Heart blocks / bradycardia cases. Large target areas requiring large

doses of anesthesia.

Compositon Of Local anesthesia

It consist of: 1. Local anesthetic

agent(lignocaine)- 2% 2. vasoconstrictors(epinephrine

bitarte)- 1:80,000. 3. Buffering agent- NaCl- 6mg 4. Reducing agent(sodium

metabisulphite)-0.5 mg/ml. 5. Preservative(methyparaben)- 1mg 6. Distilled water(used as vehicle).

Types of syringe:

Non-disposable a. Breech-loading,mettalic,cartridge-type,

aspirating. b. Breech-loading,plastic,cartridge-type,

aspirating. c.Breech-loading.mettalic,cartridge-

type,self-aspirating. d.Pressure e.Jet injector Disposable. “Safety” syringes.

ADA criteria for LA syringes

They must be durable and able to withstand repeated sterilization without damage.

They should be capable of accepting a wide variety of cartridge and needles.

They should be inexpensive,self contained, light weight & simple to use with one hand.

They should provide for effective aspiration & be constructed so that blood may be easily observed in cartridge.

Needle types

When needles are selected for use in various injection techniques,there are 2 factors of importance that must be considered:

-GAUGE -LENGTH.GAUGE: It refers to diameterv of lumen of the

needle; the smaller the number,the greater is diameter of lumen.

There is growing trend toward the use of smaller diameter or higher gauge needles on the supposition that they are less atraumatic. However it is observed that patients can’t differentiate among 23,25, 27 & 30 gauge needles.

Advantages of large-gauge needles over smaller gauge needles are:

- Less deflection as the needle passes through the tissue.

- Greater accuracy & thus increased success rates. - Needle breakage is less likely to occur. The most commonly used needles in dentistry are

25,27 & 30 gauge. 25 gauge needle preferred for all injections posing a

high risk of positive aspiration. 27 gauge can be used for all injection techniques

provided aspiration percentage is very low & tissue penetration depth is not great.

Length of needle:

These are available in 2 lengths: - long( approx 40 inches). - short(approx. 25mm).Needles should not be inserted into tissues to

their hubs unless absolutely necessary for the success of the injection.

Long needles are preferred for all injection techniques requiring penetration of significant thicknesses of soft tissue.

Short needles may be used for injections that do not require the penetration of significant depths of soft tissues.

In dentistry, local anesthesia is used to anesthetise the nerves supplying the teeth to carry out various procedures. E.g. extraction,root canals,flap surgery.

Various methods of anesthetising the nerves are:

Nerve block: depositing the anesthetic solution in close proximity to a main nerve trunk.

Field block: when solution is deposited in proximity to larger terminal nerve branches.

Local infiltration: when small terminal nerve endings are anesthetised.

Intraligamentary technique: forcing the anesthetic solution into PD membrane space under pressure to provide single tooth anesthesia.

Topical analgesia: anesthetising free nerve endings in accessible structures where stimulation by application of solution directly to the surface is not suitable.

NERVE BLOCKS

These are classified as: 1.) Maxillary blocks: It consist of a. Posterior superior alveolar block b. Infraorbital block c. Nasopalatine block d. Greater palatine block. 2.) Mandibular nerve blocks: It consist of a. Inferior alveolar block. b. Long buccal nerve block. c. Lingual nerve block. d. Mental block. e. Incisive block.

Maxillary nerve blocks

Posterior superior alveolar block: Anatomical landmarks are: 1. muccobuccal fold & its concavity. 2. zygomatic process 3. infratemporal surface of maxilla. 4. anterior border & coronoid process of ramus of mandible. 5. tuberosity of maxilla.

Indications: For operative procedures on molars & supporting structures but must be combined with palatal injection.

No subjective symptoms appeared.

Technique: The operator moves left fore-finger over

muccobuccal fold in a posterior direction from bicuspid area until zygomatic process & rest fingertip in concavity in the fold; here finger is rotated & hand is lowered to keep it in a plane at right angle to occlusal surface of maxillary teeth & at 45’ to patient’s sagittal plane. Needle is inserted in a line parallel with this finger at 45’ in upward,inward & backward direction.

Always aspirate before injecting so as to avoid injecting solution into vessels.

Solution deposited – 1.8 ml

Infraorbital block

Anatomical landmarks are: 1. Infraorbital ridge. 2. Infraorbital depression. 3. supraorbital notch. 4. Infraorbital notch. 5. Anterior teeth. 6. pupils of eye. Indications: any procedure to be

performed on 5 anterior maxillary teeth on same side of median line.

Technique:

Patient is tilted so that maxillary occlusal plain is at 45’ angle to floor;locate the infraorbital notch & finger should be moved downward about o.5 cm,where a shallow depression will be felt. Then thumb of operator is placed over located infraorbital foramen & index finger is used to retract lip; now either of 2 directions can be used.

In bicuspid approach, needle is inserted in a line parallel with supraorbital notch,pupil of eye, notch & 2nd bicuspid.

In central incisor approach, needle bisects the crown of central incisorfrom mesioincisal angle to distogingival angle

Needle shouldn’t be inserted more than 5mm. Solution deposited -2 ml Subjective symptoms – numbness of upper lip,lower eyelid

& nose on the affected side.

Nasopalatine block

Anatomical landmarks are: 1.) central incisor 2.) Incisive papilla in midline of

palate. Indications: for palatal anesthesia – a.) to supplement the ASA & PSA

blocks. b.) to complete anesthesia of

nasal septum. Solution deposited – 0.25 to o.5ml

Technique:

It is extremely painful injection unless preparatory injection is made. The preparatory injection is made by inserting the needle at right angle to labial plate between the central incisors & 0.25ml solution is deposited. Needle is then withdrawn & reinserted in crest of papilla advancing slowly into incisive foramen & 0.25 ml solution is deposited.

Subjective symptoms – numbness in palate when contacted with tongue.

Greater palatine block

Anatomical landmarks are: 1.) 2nd & 3rd maxillary molars. 2.) palatal gingival margin of 2nd & 3rd

maxillary molars. 3.) midline of palate. Indications: 1.) For palatal anesthesia used in

conjuction with PSA & ASA blocks. 2.) For surgery of posterior portion of hard palate.

Technique:

The greater palatine foramen is approached from opposite side which is situated 1 cm from palatal gingival margins of 2nd & 3rd maxillary molars towards the midline. The needle should be kept as near to a right angle as possible.

This nerve may be blocked at any point along its anterior course after emergence from foramen

Solution deposited- 0.25 to 0.5 ml Subjective symptoms – numbness felt in

posterior palate when contacted with the tongue.

Mandibular Blocks

Inferior alveolar nerve block Anatomical landmarks are: 1. mucobuccal fold. 2. external oblique ridge. 3. anterior border of ramus of mandible. 4. retromolar triangle. 5. internal oblique ridge. 6. pterygomandibular raphe. 7. buccal pad

Indications:

Analgesia for operative dentistry on all mandibular teeth.

Surgical procedures on mandibular teeth & supporting structures when supplemented by lingual or buccal nerve block.

Diagnostic & therapeutic purposes.

Technique:

Operator palpates the mucobuccal fold with left index finger;it is then moved posteriorly with external oblique ridge on anterior border of ramus. Finger is then moved up to the coronoid notch; slowly move the finger lingually across retromolar triangle & onto internal oblique ridge.

Needle is then inserted parallel to the occlusal plane of mandibular teeth from opposite side of mouth at a level bisecting the finger penetrating pterygomandibular depression.

Solution deposited – 1.8 to 2 ml Subjective symptoms- tingling & numbness of lower

lip & when lingual nerve is also affected,tip of tongue.

Lingual nerve block Anatomical landmarks are same as for

the inferior alveolar nerve. Indications – for surgical procedures of anterior 2/3rd

of the tongue,floor of the oral cavity & mucous membrane on lingual side of the mandible.

Technique: same as for IAN block. Subjective symptoms: tingling &

numbness of anterior 2/3rd of the tongue.

Long Buccal nerve block

Anatomical landmarks are: 1. external oblique ridge. 2. retromolar triangle. Indications: surgery on mandibular

buccal mucosa & to supplement IAN block.

Technique- needle is inserted into the buccal mucosa just distal & buccal to last molar.

Solution deposited- 0.25 to 0.5 ml. No subjective symptoms appeared.

Mental nerve block

Anatomical landmarks are- mandibular bicuspids

Indications- For surgery on lower lip or mucous membrane in mucolabial fold anterior to mental foramen when IAN block in not indicated.

Technique- apices of bicuspid are estimated & needle is inserted into muolabial fold after cheek has pulled to buccal side.

Solution deposited- 0.5 to 1 ml Subjective symptoms- numbness of lower lip on

injected side.

Incisive nerve block

Anatomical landmarks are same as for mental nerve block.

Indications- for anesthesia of labial mandibular structures,anterior to mental foramen & lower lip when IAN block is not indicated.

Technique- it is same as for mental nerve block except needle should penetrate into the mental foramen

Subjective symptoms- numbness of lower lip.

Local Infiltration No anatomical landmarks are required. Indications:Anesthesia of restricted area of

the mucous membrane for limited soft tissue surgery.

Technique- needle is inserted beneath the mucous membrane into the underlying connective tissue & the area is infiltrated with anesthetic solution.

No subjective symptoms are observed.

SUPPLEMENTAL ANESTHESIA

There are three techniques which are used: 1. Intraligamentary injection. 2. Intraosseous injection. 3. Intrapulpal injection. 1. Intraligamentary injection:In this solutions

are forced through the cribriform plate into the marrow spaces around the tooth.

Operator experiences strong back-pressure while injecton.

The WAND(new technology for intraligamentary technique): A computer assisted LA delivery system was introduced that can be used to administer intraligamentary injection.

2. Intraosseous injection: (Stabident & X-tip systems)

It delievers a LA solution directly into the cancellous bone adjacent to the tooth to be anesthetised.

Infiltration injections are not effective for anesthesia in mandibular molars teeth bacause of the thickness of the cortical plate.

2 intraosseous systems have been clinically studied:

Stabident system. X-tip system.

1.Stabident system: it is composed of a slow speed handpiece driven perforator,a solid 27 gauge wire with a bevelled end that drills a small hole through the cortical plate. The solution is delievered to the cancellous bone through the 27 gauge ultrashort injector needle placed into the hole made by the perforator.

2. X-tip system:

This system consists of an X-tip that separates into 2 parts, the DRILL & the GUIDE SLEEVE.

The drill is a special hollow needle leads the guide sleeve through cortical plate, whereupon it is separated & withdrawn.

The remaining guide sleeve is designed to accept a 27 gauge needle for injection. The guide sleeve is removed after the intraosseous injection is complete.

Inspite of proper techniques followed & proper solution used, there are many conditions which lead to inadequate or incomplete anesthesia.

Inadequate anesthesia:

Reasons are: 1. Presence of inflammation or infection leads to

acidic pH thus resulting in inactive cationic form of anesthetics.

2. Morphological changes in nerve trunk central to the periphery.

3. Shifting of sodium channel expressions from TTX sensitive to TTXr during neuroinflammatory reactions & TTXr sodium channels play a role in sensitising C fibres & creating inflammatory hyperalgesia.

4. Anatomic limitations such as dense bony plates, aberrant distribution of neural bundles or accessory innervation .

5. It may also result from not allowing enough time for the anesthesia to work.

So in resistant cases alternative anesthetics should be used eg. Bupivacaine

In cases of anatomic limitations we can use supplementary intraligamentary or intraosseous injections.

Hot tooth

The term "hot tooth" is a common name given to an infected tooth which exhibits severe pain. Sometimes, hot teeth have living nerve tissue inside of them, but the extent of

inflammation prevents the tooth from being able to recover. Such teeth are generally diagnosed with irreversible pulpitis.

Many times hot teeth will no longer be vital (i.e. they no longer have living tissue inside of them). Such teeth are termed necrotic, and have hollow root canals open to the inside of the body.

If bacteria gain access to the root canals of necrotic teeth, they can create a significant colony before the body's immune system even knows they are present. Large bacterial colonies are capable of producing a significant amount of tissue destroying enzymes and acids, and when the immune system begins to fight the infection, the bone and soft tissues around the tooth can be extremely tender even to light finger pressure.

Hot teeth & the area around them can be difficult to anesthetize,due to the acidic environment & the amount of infectious fluid present. It shifts the sodium channel expressions to TTXr(resistant) frm TTX sensitive.

Many times treating the tooth comfortably requires localizing the infection with antibiotic medication prior to performing endodontic (root canal) procedures on the tooth.

Anesthesia is of great importance in routine dentistry. But these solutions should be cautiously used as it may cause toxicity or complications either because of lack of operator’s skill or contaminated anesthetic solution.

Thank you…!!!!