Anaesthesia Review Booklet by Dr. Aryan (Medical Booklet Series by Dr. Aryan Part 9)

Anesthesia Review
(A Free Booklet Series by Dr. Aryan)

Preface:
• This is the study material designed by Dr. Aryan with creation and compilation of the best
of the best and the most finest slides on the subject. I would like to offer a billion heartily
thanks for everyone who contributed directly or indirectly to the creation of the material
through creation and dissemination of the scientific information.
• Covering everything in one study material is next to impossible. Hence, refer to gold
standard textbooks for building solid concepts or in case of any doubt. Textbooks are
acknowledged at the end of the presentation. If any source has been missed to
acknowledge, it doesn’t lessen their impact and contribution in any way.
• Don’t keep searching for pattern between the consecutive slides. You won’t find many.
Rather to boost your recall and review, I have constructed many slides and are deliberately
placed with no much relation between the preceding and the succeeding ones.
• The main rule of a review material is that it must make you recall or learn maximum
amount of information in minimum amount of time and space.
• Motivational quotes and articles are included within the slides. Always remember that
every good idea, nice piece of information and everything else is literally and absolutely
worthless unless you execute.
• If you know everything in the slides in much detail, you probably wouldn’t need this
material.
Best of luck WORK & SUCCESS! Dr. Aryan
(Anish Dhakal)

Ten Golden Rules of Anesthesia (@ANESTHESIA):
1. Assessment and preparation of the patient
2. Nil per oral
3. Equipment, drugs made ready
4. Suction
5. Tilting table
6. Have a Vein open
7. Evaluate Vitals
8. Somebody to help
9. Intubation
10. Airway clear
Dr. Aryan (Anish Dhakal)

Mallampati Classification

What is Anaesthesia?
Reversible drug induced loss of sensation with or
without muscle relaxation and loss of
consciousness.

Balanced anesthesia by John Lundy also includes amnesia, abolition
of reflexes and homeostasis maintenance

Guedel’s stages of anesthesia:

Airway Assessment:
Mouth opening > 2 fingers
Thyromental distance > 6.5 cm
Neck mobility free
TMJ free
Mallampati grading
Teeth (Loose/False)

Pearls for Calculations
 1 % = 10 mg/mL
1:20000 = 1 gm in 20000 mL
Lignocaine: 4.5 mg/kg (with adrenaline its 7 mg/kg)
Bupivacaine: 3 mg/kg (with or without adrenaline)

Ketamine in a Nutshell
NMDA antagonist, produces dissociative anesthesia
Emergence reactions (vivid dreaming, illusions, excitement, euphoria,
confusion), hallucinogens, nightmares
Increased many physiological parameters (ICP, IOP, BP, HR, skeletal muscle
tone, salivation, respiration, etc.)
Pharyngeal and laryngeal reflex preserved
Potent bronchodilator (beneficial for asthmatics)
Beneficial in hemodynamically unstable patients, less resources
Pediatric anesthesia
Can be given intramuscularly as well
COI in airway obstruction, psychiatric disorders, conditions with raised
parameters e.g. ICP/ IOP/ BP, pheochromocytoma, hyperthyroidism

Milky white oil based emulsion containing soya bean oil, glycerol & egg
lecithin
Used within 6 hours after the vial is opened, potentiate GABA
Early smooth induction (15 seconds) and recovery, inactive metabolites
Antiemetic, antipruritic & also bronchodilator (like ketamine)
Safe in porphyria patients, patient at risk of malignant hyperthermia & head
injury (no rise in ICP unlike ketamine)
Pain on injection site, CVS depression, respiratory depression, excitatory
phenomenon like myoclonus and convulsions, sepsis if used after 6 hours,
propofol addiction, propofol infusion syndrome
COI in airway obstruction, pregnancy and lactation, children less than 3 years,
known hypersensitivity, etc.
Propofol in a Nutshell

Ultra short acting barbituric acid derivative
Acts as anticonvulsant & at sub anesthetic dose as anti-analgesic
agent (reduced the pain threshold)
Decreased many parameters like ICP, IOP, BP, respiration, skeletal
muscle tone, etc.
Laryngospasm, bronchospasm (unlike other two) & post-operative
disorientation
COI include porphyria (use propofol), asthma, shock/hypotensive
patient, etc.
Thiopentone in a Nutshell

Semi-closed Circuits (Mapleson circuits)
Magill (Type A): circuit of choice for spontaneous ventilation
Bain (Type D modification): circuit of choice for controlled ventilation
Type E & Type F: pediatric circuit

Depolarizing Vs. Non depolarizing Block
Non-depolarizing block: Train of four & reversal needed (atropine or glycopyrolate is used
to counteract the adverse effects of the reversal agent neostigmine).

Depolarizing blockers are Succinyl choline and Decamethonium

TYPES of ET Tubes:
ET tubes can be :
- cuffed - uncuffed
Cuffed ET tubes are used in children > 10 years
The cuff tube helps in proper position and prevents
aspiration
In children < 10 uncuffed ET tubes are used because the
narrow subglottic area performs the function of a cuff and
prevents the ET tube from slipping (if cuffed in such a
narrow area, can cause pressure necrosis)
Cuff pressure Less than 30cm of H2O
Cuff placement 2-2.5cm below vocal cord
Cuff volume 4-8ml of air is required to fill the cuff

Male: ID 9 mm Female : ID 8 mm
 New born : ID 2.5 mm
 0-6 months : ID 3 to 3.5 mm
 0.5- 1 year : ID 3.5 to 4.0 mm
 1- 6 yrs : ID = (Age/3) + 3.5
 > 6 yrs : ID = (Age/4) + 4.5
Size of endotracheal tube : internal diameter (ID)
Smallest tube available is 2.5 mm and largest is 10.5 cm

Length of endotracheal tube :
Adult -> Male = 23 cms, Female = 21 cms
Children
Oral endotracheal tube = (Age/2) + 12 (cm)
Nasal endotracheal tube = (Age/2) + 15 (cm)
The tube should lie 4-5 cm above the carina or is 2-2.5 cm below the vocal cord

Indications of Endotracheal Tube:
• In emergency medicine
• acute respiratory failure
• inadequate oxygenation or ventilation
• airway protection in a patient with depressed mental status
• In the perioperative setting
• patients receiving general anaesthesia
• surgery involving or adjacent to the airway
• unconscious patients requiring airway protection
• surgery involving unusual positioning
• Less frequently
• short-term hyperventilation to manage increased
intracranial pressure
• to manage copious secretions or bleeding from the airway

Sniffing position
Flexion at lower cervical spine
Extension at atlanto-occipital joint
Achieved by placing a 6-8 cm thick pillow
under the occiput

Indications for Nasotracheal Intubation:
• Obstructing mass in oral cavity
• Oral surgery
• Inadequate mouth opening:
• Fracture mandible
• Temporomandibular joint ankylosis
• Ludwig angina
• Better tolerated if tube is to be kept for prolonged time and patient is
also awake

Disadvantages of Nasal Intubation:
1) Trauma to nasal mucosa
2) Risk for bleeding
3) Risk for bacteremia (sinusitis, otitis,
meningitis)
4) Smaller diameter than oral route ->
difficult for suction

Checking for the correct position of the tube
• Auscultation of the chest for air entry (epigastric, B/L lung bases & B/L
axillary areas)
• Characteristic feel of bag
• Chest inflation on positive pressure
• Capnography (measuring end tidal CO2): It is surest sign
• Fiberoptic bronchoscopy: It is also confirmatory but practically not
feasible

Oropharyngeal adjuvant airway:
Guedel’s Airway
Water’s airway
Safar airway
Brook airway

Laryngeal mask airway
• LMA is a specialized airway device made of wide bore PVC tubing,
which incorporates a distal inflatable non-latex laryngeal cuff
• Also called as
• Supraglottic Airway Device
• Brain Mask (Archies Brain)

Contraindications to LMA:
• Risk factors for gastric aspiration
• Oropharyngeal or retropharyngeal pathology, or foreign
bodies in the hypopharynx
•Limited mouth opening. (e.g., wired jaw, TMJ disease)
• Cervical vertebrae or laryngeal cartilage fracture.
• Patients requiring positive pressure ventilation with airway
pressures of greater than 20 cm H20

Size Selection (@Weight: 5-5-10-10-20-20-30…&
Volume = 4, 7, 10, 14 then (size-1)*10 mL)

Complications of LMA:
Aspiration of gastric contents
Local irritation
Upper airway trauma: Pressure-induced lesions, Nerve palsies
Complications associated with improper placement: Obstruction, Laryngospasm
Complications associated with positive pressure ventilation: Pulmonary
edema, Bronchoconstriction

Rationale of PAC
• To obtain information and perform physical examination
• To assess risks of anesthesia and surgery
• To order special investigation if any
• To choose and plan anaesthetic management, prescribe premedication
• To obtain written informed consent after adequate counseling

Contraindications to Spinal & Epidural
Anesthesia:
Absolute:
• Patient’s refusal
• Coagulopathy
• Skin infection at site of
insertion
• Increased ICP
• Allergy to Local Anaesthetic
drugs
Relative:
• Uncooperative patient.
• Pre-existing neurological
disorder.
• Fixed cardiac output states (AS,
MS, HOCM, 3rd degree heart
block).
• Anatomic abnormalities.
• Hypotension / hypovolaemia

Goals of Premedication

Rapid Sequence Induction (Sellick Maneuver):
For use in unresponsive
patients without a cough
or gag reflex
Prevents regurgitation and
aspiration
Used during endotracheal
intubation

Perioperative fluid requirement:
1. Maintenance fluid = 4, 2, 1 rule hourly
2. Fasting deficit = Maintenance fluid*No. of hours fasted (50%, 25%
and 25% in 1st, 2nd and 3rd hour respectively)
3. Third space loss = 2 mL/kg, 4 mL/kg and 6-8 mL/kg in minor,
intermediate and major operations respectively
4. Compensatory intravascular expansion = For GA its 5 mL/kg
Under spinal/epidural its 10-15 mL/kg
5. Ongoing loss:
Blood loss = Gravimetry (1 fully soaked gauage = 15-20 mL, 1 fully
soaked tetrad big gauge = 150 mL, 1 fist of blood clot = 400-500
mL) OR Volumetry
Urinary loss = 0.5-1 mL/kg (2 mL/kg in infants)

What are the differences between crystalloid and colloid solution?
Crystalloid Colloid
Composition
Concentration
Pressure
Distribution
Haemo. Para.
Volume req.
X matching.
Oedema.
Anaphylaxis.
Cost
Water+electrolytes High mol wt subs.
Iso, hypo or hypertonic Hypetonic
Osmotic pressure Oncotic pressure.
Extravascular spa. Intravascular sp.
Transient Sustained.
3 times of loss Equal to loss.
No effect Interfere.
Produce do not.
No do occur.
Economic costly

Blood transfusion:
Estimated Blood Volume( EBV):
Allowable Blood Loss ( ABL) ml:
= EBV × { ( Initial Hct - Final Hct) / Initial Hct }
Intraoperative blood transfusion is done:
• preoperative deficit ( anaemic)
• Blood loss ≥ ABL (Pediatric group ˃ 10 % EBV )
Neonate preterm 95 ml/kg
Term 85 ml/kg
Infant 75 ml/kg
Children 70ml/kg
Adult 65ml/kg

Train of Four: Non Depolarizing Block

Benefits of Recovery Position:
1. Mouth faces down: vomit/ blood can drain out, tongue doesn’t fall
back
2. Chin up: epiglottis is opened
3. Prevents tilting of esophagus thus prevents passive regurgitation
and aspiration
4. Arms and legs locked, patient is stabilized
5. Pregnant women in left lateral position prevents IVC compression
6. If wound in the chest, placing patient with wound down will protect
the normal lung

Guidelines for Fasting before a Surgery:
Clear liquids (water, pulpless juice, black tea): 2
hours fasting
Breast milk: 4 hours fasting
Light meal, Infant formula milk: 6 hours fasting
Heavy meal: 8 hours fasting

For epidural, its Tuohy’s needle with huber tip

Lumbar Puncture Layers

Spinal Anaesthesia:

Prevention & Treatment of Complications in Spinal Anesthesia:
Hypotension (Intraoperative) Post dural puncture headache (Postoperative)
Prophylactic: Fluid loading 1-1.5 L crystalloid Use of small bore or dura splitting needle
Head low position (Trendelenburg position) Adequate hydration (preloading of fluids)
Vasopressors (ephedrine, epinephrine, etc.) Avoid spinal in patient with history of headaches
Inotropes (dopamine, dobutamine) Avoid pillows and sitting/standing in immediate
post operative period
Oxygen supplementation Let patient to lie supine (Trendelenburg position)
Analgesics, Desmopressin, IV fluids & Abdominal
binder
Inhalation of 5-6 % carbon dioxide in oxygen
(vasodilator increase CSF production)
Oral or IV caffeine (500 mg in 1 liter of RL) inhibit
vasospasm
Epidural or blood patch: autologous blood given
in same or adjacent epidural space

Spinal Anaesthesia Epidural Anaesthesia
Onset is faster, dose small and for less duration Onset is slower, dose larger and for prolonged duration
(epidural catheter in situ)
Complete Anaesthesia Incomplete or patchy block
Once fixed, cannot change the level of block Can change the level of block
Only at lumbar level At any level
Easier and less costly Technically difficult and more costly
Surgeries of lower limbs, pelvis, lower abdomen,
Obs/Gyane
In addition in surgeries of thorax, neck and also
postoperative analgesia
Post spinal headache seen No incidence of headache. Less hypotension and
hemodynamic alteration (safer in cardiac patients)
Complications like total spinal anaesthesia, epidural
hematoma, IV injection, block failure, drug toxicity and
catheter related problems are less seen
More often complications like total spinal anaesthesia,
epidural hematoma, IV injection, block failure, drug
toxicity and catheter related problems

Contraindications of LA with adrenaline:
Ring block of fingers, toes, pinna, tip of nose, penis (vasoconstriction
in end circulation may lead to hypoxia and necrosis)
With halothane (as it sensitizes heart to arrythmogenic effect of
catecholamines)
MI patients and patients with hypertension
Bier’s block (IV regional anaesthesia)
Coronary artery disease or arrhythmia
Hyperthyroidism
Note: Sodium bicarbonate is added to LA so that it increases pH and more drug exists
in unionized form (faster crossing of axonal membrane binding to sodium channel
alpha receptor & faster onset of action)

LA can also cause hypersensitivity reaction (PABA and methyl paraben),
methemoglobenemia, malignant hyperthermia or local toxicity (pain, sloughing, necrosis,
breakage of needles).

Spinal drugs:
Lignocaine 5% (Hyperbaric)
Bupivaciane 0.5% (Hyperbaric)
Tetracaine 1%
Procaine 10%
Opoids: fentanyl (with bupivacaine in epidural it can used to execute
painless labour of postoperative pain management)
Intrathecal ketamine

Acknowledgements:
Best of the best slides, pictures and information on the web. Special
thanks to all those brilliant minds for their act of creation and
compilation of scientific material without which this work would not
be possible
Short Textbook of Anesthesia, Ajay Yadav
Sullivan’s Anesthesia for Medical Students
Handbook of Local Anesthesia, M. Stanley
Lecture notes

Why do people always rush to judge others?
https://medium.com/@anishdhakal718/why-people-always-rush-to-
judge-others-99f4265306c

Anaesthesia Review Booklet by Dr. Aryan (Medical Booklet Series by Dr. Aryan Part 9)

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