from basic to advance Anaesthesia and its types in detail.

1. ANAESTHESIA
Dr. Divya Gangwar

2. ■ Anesthesia or anaesthesia is a state of controlled, temporary loss of sensation or
awareness that is induced for medical or veterinary purposes. It may include some or
of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), amnesia
(loss of memory), and unconsciousness.

3. PREOPERATIVE ASSESSMENT
■ History
■ Chronic cough, smoking, alcohol, drug intake, drug allergy.
■ Any previous diseases like hypertension, diabetes mellitus, epilepsy, bronchial asthma,
tuberculosis, hepatitis, cardiac diseases.
■ Drug therapy: Steroids, antihypertensives, sedatives, antibiotics, antiepileptics.
■ Examination General:
■ Posture, teeth, mouth opening, dilated veins, neck movements, tremor, airway, anaemia, oedema,
jaundice, cyanosis.

4. ■ Respiratory system: To look for asthma, tuberculosis, emphysema, COPD.
■ Airway: Mouth opening, Mallampati scoring, thyromental distance, temporomandibular joint
assessment.
■ Thyromental distance: It is the distance between mentum and thyroid cartilage, measured
externally. If it is more than 6.5 cm (i.e. more than 4 fingers breadth) intubation is easier, if it is
less than 6.5 cm intubation is difficult.

5. ■ Cardiovascular system
Hypertension, ischaemic heart disease, arrhythmias, cardiac failure, valvular diseases.
Spine: Curvature, intervertebral space, skin over the area for any infection.
Other systems: Abdomen, skeletal system.

6. Scoring to assess intubation Mallampati scoring
■ Class I — Faucial pillar, soft palate, uvula are seen
■ Class II — Faucial pillar, soft palate are seen
■ Class III — Only soft palate is seen
 Samsons Young modification:
■ Class IV — Only hard palate seen
■ Class I, II: Easy intubation
■ Class III, IV: Difficult intubation

7. Preoperative Investigations
■ Hematocrit,
■ blood sugar,
■ blood urea,
■ Serum creatinine,
■ Electrolytes,
■ chest-X ray,
■ ECG, blood grouping,
■ Blood-gas analysis,
■ Cardiac assessment.

8. Preoperative Treatment
■ Control of respiratory and cardiac diseases.
■ Improvement of Hb% status, if anaemia is present.
■ Preoperative antibiotics are given.
■ Blood should be kept ready for major cases.
■ Starvation for 4 hours for liquids and 6 hours for solids.
■ Bladder and bowel should be emptied to prevent soiling on the operation table.
■ Urinary catheter may be passed and enema may be given.
■ Dentures, contact lenses, jewellery must be removed.
■ Surgical area should be cleaned and properly prepared.

9. INSTRUMENTS IN ANAESTHESIA
■ 1. Boyle’s apparatus: It consists of:
■ a. Cylinders for N2O and O2.
■ b. Pressure gauge—to know the amount of gas remaining.
■ c. Pressure regulator—to regulate the pressure of gas used.
■ d. Rotameter—to know the flow of gas.
■ E. Vapouriser.

10. ■ 2. Endotracheal tube:
These are tubes inserted into the trachea and is used to conduct gases and vapours to and from the
lungs.
Depending on the diameter, it is available in various sizes.
It has a cuff at one end which, when inflated stabilizes the tube in position and also prevents
regurgitation. Non-cuffed tubes are also available.
The other end near the mouth is connected to the breathing circuit through which anaesthetic gases
are delivered.
The tube is inserted using a direct laryngoscope.
The proper placement in the airway is confirmed by auscultating for the breath sounds over the chest
when the gases are delivered.

11. ■ Complications :
Post Operative sore throat
Hoarseness after intubation
Upper airway oedema

12. Premedication
■ It is given one hour before surgery:
■ For sedation and relief of anxiety. Pethidine 50 mg/ morphine 10 mg/diazepam 10 mg, midazolam
1–2.5 mg.
■ To suppress vagal activity. Atropine 0.6 mg IM.
■ To reduce vomiting. Promethazine (phenargan) 12.5 mg.

13. Induction
■ Patient is preoxygenated with 100% oxygen for 3 minutes then induced with IV thiopentone,
given 4–5 mg/kg. Patient loses consciousness. Induction is maintained by 67% nitrous oxide and
33% oxygen.
■ Scoline is given IV to relax muscles so as to facilitate endotracheal intubation.
■ Once intubated, ventilation can be either controlled using muscle relaxants or spontaneous using a
volatile anaesthetic agent.
■ Reversal is done using neostigmine and atropine or glycopyrrolate.

14. 1. General Anesthesia
■ This type is used when a patient is undergoing major operation like knee and hip replacements,
heart surgeries or to treat cancer.
■ These surgeries and treatment can not be performed without giving general anesthesia.
■ GA body, you will be unconscious and many of your body functions will be slowed down.
■ The doctor will place a thin tube in your throat which will help you to breathe.
■ During the entire procedure, your anesthesiologist will keep monitoring your heart rate, breathing
and blood pressure to make sure everything is going well and you are free of pain.
■ It has got three components: (1) Analgesia; (2) Hypnosis; (3) Muscle relaxation

15. ■ Components of general anaesthesia™
 Premedication
 Induction
 Maintenance
 Recovery

16. Anaesthetic Agents
 Volatile anaesthetics: They vaporise in room air.
Agents used are: Ether, trichloroethylene, halothane, enflurane, isoflurane, sevoflurane.
Ether which is irritant, unpleasant, flammable, is commonly used agent in developing countries.
Enflurane and isoflurane are non-inflammable, non-explosive, non-irritant and stable. Here
anaesthesia is rapid with faster recovery.
 Gaseous anaesthetics
Nitrous oxide: It is non-inflammable, non-irritant, good analgesic but weak anaesthetic agent. It is
given along with 30–50% oxygen for balanced anaesthesia (blue coloured cylinder in India).
Cyclopropane is highly flammable

17. Intravenous Anaesthetics
 Thiopentone: It is ultrashort acting barbiturate which causes hypnosis during induction
of anesthesia.
It does not have analgesic effect.
It causes hypotension, respiratory depression, laryngeal and bronchospasm.
Recovery is rapid. Extravasation of drug can cause skin ulceration.
Intra-arterial injection causes vasospasm and gangrene. Dose: 4–7 mg/kg. Methohexitone
sodium.
Propanidid: 4–7 mg/kg. It can cause anaphylaxis.

18.  Ketamine: Dose: 2 mg/kg IV. It is a good analgesic.
It causes dissociative anaesthesia.
It can lead to hypertension, apnoea, laryngospasm. In children it can be given IM-5 mg/kg. It does not
require intubation for small procedures.
 Propofol
It is widely used induction agent which has got predictable onset and recovery.
It has got least side effects on CVS and respiratory system.
It is also used for total IV anaesthesia. Dose: 1–2.5 mg/kg.

19. ■ OXYGEN
Oxygen is given through Boyles apparatus (33.3%).
Oxygen in high concentration is respiratory depressant and also affects eyes.
A 5% CO2 mixture in oxygen is called as carbogen.
Oxygen is available in black and white colored cylinder.

20.  Administered :
■ It works on the brain and the central nervous system of the patient and makes
him/her unconscious and unaware.
■ The anesthetic is administered to the circulatory system of the patient through
injected drugs or inhaled gases.
■ This kind of anesthesia is opted for major surgeries which may involve
significant blood loss, breathing difficulty, etc.

21. COMPLICATIONS OF GENERAL ANAESTHESIA
■ Intra-arterial injection of the drug.
■ Myocardial depression and cardiac arrest.
■ Hypertension.
■ Laryngeal and bronchial spasm.
■ Cardiac arrhythmias. Respiratory failure.
■ ARDS.

22. 2. Regional Anesthesia
■ It is only given to numb the particular part of the body that would feel pain and
the patient is still conscious but sedated.
■ It is provided by a nurse anesthetist.
■ Anesthesia injection is given on the area with a numbing medication that causes
unconsciousness below the injection site.
■ For example, if you are undergoing hand surgery, then your anesthesiologist
will numb your entire hand and will continue your surgery.

23. ■ Xylocaine: It is the commonest local anaesthetic agent used.
■ It is available as 0.25–5% concentrations.
■ It is metabolized in the liver and excreted in the kidney as xylidines.
■ It is also an antiarrhythmic drug and so commonly used in cardiology and
cardiac surgery.
■ Side effects: Giddiness, headache, postural hypotension, tinnitus, circumoral
anaesthesia.
■ Dose: 4 mg/kg effect lasts for 90 minutes

24. Xylocaine with adrenaline has got longer duration of action.
It creates relatively bloodless field. But it should not be used in places where end
arteries are present like glans penis, ear lobule, tip of the nose, lip, fingers and
toes.
■ Bupivacaine (Marcaine)
It has got prolonged action. It is a vasodilator also.
Dose: 3 mg/kg.
Epidural block: 0.5% x Spinal: 0.5% 3 ml.

25. ■ TOPICALANAESTHESIA
It is used for minor surgeries of eye, laryngoscopy, bronchoscopy, cystoscopy, gastroscopy.
It is available as instillation, spray, viscous, ointment, gel, EMLA (Eutectic mixture of local anaesthetic).
■ NERVE BLOCK
Block of inferior dental nerve and lingual nerves in the region of the mental foramen for extraction of teeth.
Finger block of digital nerves. Here plain xylocaine is used (without adrenaline).
Intercostal block.
Ankle block.
Median and ulnar nerve block.

26. ■ Brachial plexus block (Winnie’s block).
■ It can be given through: Interscalene. Axillary. Supraclavicular approaches. Supraclavicular
approach is commonly used.
■ 1 cm above the midpoint of the clavicle, needle is passed downwards, backwards and medially
towards first rib. Once needle hits the first rib, 15–20 ml of 1.5% xylocaine is injected (with
walking or stepping over the first rib). Complications are pneumothorax and injury to the great
vessels. Other blocks:
■ Cervical plexus block.
■ Sciatic nerve block.
■ Femoral nerve block.

27. ■ INTRAVENOUS REGIONALANAESTHESIA (BIER’S BLOCK)
Limb is exsanguinated and occluded with tourniquet.
Pressure in the tourniquet must be 30 mmHg more than the systolic pressure of the patient. Needle is
placed in the selected vein. 40 ml of 0.5% xylocaine for upper limb and 80 ml of 0.25% of xylocaine
for lower limb is injected into the vein.
Xylocaine with adrenaline should not be used.
It gives very good analgesia for 2 hours.
Side effects: Sudden release of drug into the circulation can cause hypotension, convulsions and often
death.
Bupivacaine should not be used.
Indications For upper and lower limb surgeries, it can be used without G/A or S/A.

28. 3. SPINALANAESTHESIA
It is the injection of local anaesthetic into the subarachnoid space causing loss of sympathetic tone,
sensation and motor function.
It is a safe and effective form of anesthesia usually performed by anesthesiologists that can be used as
an alternative to general anesthesia commonly in surgeries involving the lower extremities and
surgeries below the umbilicus
In pediatric patients, spinal anesthesia is particularly useful in children with difficult airways and those
who are poor candidates for endotracheal anesthesia such as increased respiratory risks or presence of
full stomach.
This can also be used to effectively treat and prevent pain following surgery, particularly thoracic,
abdominal pelvic, and lower extremity orthopedic procedures.[

29. Indication of Spinal Anesthesia
•Nephrectomy and cystectomy in combination with general anaesthesia
•Transurethral resection of the prostate and transurethral resection of bladder tumours
•Hysterectomy in different techniques used
•Caesarean sections
•Pain management during vaginal birth and delivery
•Urology cases
•Examinations under anaesthesia

30. ■ Drugs used:
Lignocaine 5% in 6% dextrose, 2 ml.
Bupivacaine 0.5% in 5% dextrose, 3 ml. Cinchocaine 0.5% in 6% dextrose, 2 ml.
Technique:
24–26 gauge needle with stillette is used.
Needle is passed through the interspinous space and ligamentum flavum to reach the subarachnoid
space to get clear fluid (0.5 ml/sec).
Needle is rotated 360 degrees and drug is injected slowly. Patient is repositioned to supine.
Drug takes 15 minutes to act.

31. Types of spinal anesthesia
1. Caudal (up to L5)
2. Low spinal (up to L1)
3. Mid-spinal (up to T10)
4. High spinal (up to T6)
5. Unilateral spinal

32. Advantages
■ Economical
■ Hypotension reduces the bleeding
■ Adequate relaxation is achieved
■ Respiratory complications are less

33. Complications
• Mild hypotension
• Bradycardia
• Nausea and vomiting[8]
• Transient neurological symptoms (lower back pain with pain in the legs) [9]
• Post-dural-puncture headache or post-spinal headache
• Nerve injuries: Cauda equina syndrome, radiculopathy
• Cardiac arrest
• Severe hypotension
• Spinal epidural hematoma, with or without subsequent neurological sequelae due to compression
of the spinal nerves.
• Epidural abscess
• Infection

34. Contraindications
• Local infection or sepsis at the site of injection
• Bleeding disorders, thrombocytopenia, or systemic anticoagulation (secondary to an increased risk of a
spinal epidural hematoma)
• Severe aortic stenosis
• Increased intracranial pressure
• Space occupying lesions of the brain
• Anatomical disorders of the spine such as scoliosis (although where pulmonary function is also impaired,
spinal anaesthesia may be favored)[6]
• Hypovolaemia e.g. following massive haemorrhage, including in obstetric patients
• Allergy

35. 4. EPIDURAL ANAESTHESIA
■ It is a potential space between dura anteriorly and ligamentum flavum posteriorly which has got
negative pressure inside. It extends from foramen magnum to sacral hiatus.
■ Touhy needle is used for epidural anaesthesia.
■ Once the needle is in the space there will be sudden indrawing of air or saline drop.
■ An epidural catheter is placed in the space and fixed. 2% xylocaine with adrenaline or 0.5%
bupivacaine is injected into the space to achieve anaesthesia up to the desired level.
Advantages
■ It can be used for continuous repeated prolonged anaesthesia.
■ It can be used for postoperative analgesia.
■ It can be kept for several days.

36. ■ Uses :
 Labor and delivery and surgery in the pelvis and legs .
 Procedure in the belly ,legs or feet.

37. 4. Local Anesthesia
■ It is also known as Local anesthetic which is injected in a body to make a small area of the body
unconscious.
■ Local anesthesia is given if you are undergoing skin biopsy, breast biopsy or during treatment of
fractured bone or stitching a deep cut.
■ During the procedure, you will be awake and feel some pressure, but you will not feel any kind of
a pain in the particular area.
 Administered :
■ It is applied via an injection in the surgical area in order to block the pain. Thus, it results in the
numbness of that part of the body while the person remains conscious.

38. Difference Between Local and General Anaesthesia
■ Local anaesthesia is a type of anaesthesia that numbs a small part of the body without
affecting consciousness. It is administered through an injection or topical application of
an anaesthetic medication.
■ General anaesthesia is a type of anaesthesia that affects the entire body and causes the
patient to lose consciousness. It is administered through an intravenous injection or
inhalation of an anaesthetic gas.

39. Differences between local and regional anesthesia
• Local anesthesia is used for small procedures such as getting stitches or having
a mole removed. It numbs a small area, and you are alert and awake.
• Regional anesthesia is used for more extensive surgery such as childbirth and
surgeries of the arm, leg or abdomen. It numbs a large part of the body, but you
remain aware.
• In local anesthesia, a local anesthetic is injected into the skin to allow pain-free
surgery and is used for small skin lesions or dental work.
• Regional anesthesia implies placing local anesthesia near nerves to numb an
entire extremity and is used for more extensive surgery

40. Side effects of anesthesia
• Obstructive sleep apnea – This refers to a condition when an individual stops
breathing while being asleep.
• There are several other side effects which include shivering, nausea or vomiting,
headache, sore throat, the rise in temperature, high blood pressure, delayed
return to normalcy, etc.
• There are some rare life-threatening effects which include malignant
hyperthermia, respiratory failure and even death in very rare cases.
• Other types may have effects like a prolonged period of numbness, allergies,
etc.

41. Uses of Anesthesia
• Anesthesia is sometimes used to numb the feelings of the specific part of the
human body and sometimes make you unconscious completely so that the
surgery or treatment can be done without giving any pain to the patient.
• General anesthesia is generally used when any major operation is done.
• Local anesthesia is used to make a small part of the human body unconscious.
• Regional anesthesia: It is also given to numb the specific part of the body during
the surgery. But in this type, the patient is conscious but sedated.

42. How long does anesthesia last?
■ Anesthesia may last for 45 minutes to 4 hours depending upon the anesthetic
drug used. While local anesthesia may last for an hour or so, general anesthesia
or the epidural and spinal anesthesia usually lasts for 3-4 hours.

43. How does anesthetic work?
■ Anesthesia is sometimes given intravenously and sometimes inhaled from
pressure tanks.
■ This makes you or some parts of your body unconscious so that doctors can
continue to operate and treat you without giving any pain.
■ There are a few types which are provided according to your disease.
■ The anesthesiologist will demonstrate the anesthesia awareness details and
then injects it according to the treatment and your body’s need.
■ While you will be semi conscious and your particular part of the body will be
numb, the doctors will easily continue the procedure and you will feel no pain
during the entire process.

44. four stages of anesthesia?
■ There are four different stages of anesthesia:
■ Stage of analgesia or disorientation:
■ Stage I: This phase initiates after the administration of the anesthetic dose and proceed until the
loss of consciousness.
■ Stage of excitement:
■ Stage II: In this stage, breathing, heart rate become inconstant. Pupil dilation, coughing, vomiting
may also occur.
■ Stage of surgical anesthesia:
■ Stage III: During this stage, the muscles relax, vomiting stops and breathing is slowed. The
patient is now ready to be operated.
■ Stage of overdose:
■ Stage IV: When too much of medication is administered then it result to cardiovascular or
respiratory collapse.