Anasthesia 2

Patient Monitoring

CNS Monitoring

• Purpose: Monitor anesthesia depth.

• Prevent awareness.

• Method: Bispectral Index (BIS).

• Mechanism:
• Analyzes EEG waveforms.

• Recommended BIS in GA:
• 40–60.

CVS Monitoring

Non-Invasive

• HR

• BP:
• Non Invasive
• Sphygmomanometry via
1. palpatory,
2. auscultatory,
3. oscillometric methods
• Automatic
• Invasive
• Major surgeries
• Common Line:
• Radial artery
• Allen’s Test:
• 2 hands → 1 artery
• Negative: Normal.

• Modified Allen’s:
• 2 hands → 2 artery
• Positive: Normal (radial & ulnar patent).

• ECG:
• Lead II:
• M/c sensitive for Arrhythmias.
• V1 and V2
• Septal ischemia
• V5 and V6
• Lateral ischemia

CVC vs PAC

 

Indicator	CVP	PCWP or Occlusion Pressure
ㅤ	M/c used indicator	Best indicator, more accurate.
Purpose	Right heart function	Left heart function
Equipment	CVC – Central Venous Catheter	PAC – Pulmonary Artery Catheter (Swan-Ganz)
Normal Values	CVP: 0 – 5 cm H₂O.	PCWP: 4 – 12 mmHg.
Fluid Mx	↓ CVP + ↓ BP → Give fluid ↑ CVP + ↓ BP (pump failure) → no fluid.	↑ PCWP → LV dysfunction.
Long-Term Use	For TPN, inotropes, cardiac drugs.	ㅤ
Complication	Common: Arrhythmias.	Common: Arrhythmias. Dreaded: Pulmonary capillary rupture.
Image	• CV Catheter: Triple lumen, 7 Fr (20 cm)	Swan-Ganz catheter assembly

RS Monitoring

Pulse Oximeter

• Function: Oxygenation.

• Principle: Beer-Lambert Law.

• Light:
• 660 nm (red) → reduced Hb.
• 940 nm (infrared) → oxygenated Hb.

• Limitations:
• CO poisoning
• Fire accidents
• false high SpO₂.
• MetHb/dyes
• Fe 2+ → Fe 3+
• false low SpO₂.

Capnography

• Function:
• Exhaled CO₂ → Adequate ventilation

• Principle:
• Infra-red spectroscopy.

• Normal EtCO₂:
• 35 – 45 mmHg.

Normal Waveform (Top Hat)

• Phase I:
• Dead space gas.

• Phase II:
• Expiratory upstroke.
• Upper alveoli ventilate

• Phase III:
• Alveolar plateau.
• Determine EtCO2
• Middle and lower alveoli together follow

• Phase IV:
• Inspiratory downstroke.

Abnormal Waveforms

• Bronchospasm / partial ET obstruction
• shark fin
• ↑ upstroke of phase 3
• Smokers

• Cardiogenic oscillations
• normal in children.
• d/t thin chest wall → beating heart

• Curare cleft:
• Recovering from relaxant
• During surgery → give relaxant.
• End surgery → reverse relaxant.
• Mnemonic: Curare → Need Curing → ↑ muscle relaxant

• Hypoventilation
• CNS depression (e.g., opium).
• ↑ Height → ↑ expired CO2

• Malignant hyperthermia
• Step ladder.

• Leaky sampling
• dual plateau.

• CO₂ rebreathing
• high baseline
• Fresh air is not entering / Inadequate fresh gas flow
• (exhausted soda lime/inadequate flow)

• Incompetent inspiratory valve
• slaying Phase IV.

• Single lung transplant
• 2 peaks in Phase III.

• Sudden zero EtCO₂
• accidental extubation/disconnection
• (common),
• air embolism (Not common)

• Esophageal intubation
• flatline.

Neuromuscular Monitoring

Purpose:

• Assess relaxation recovery.

Method:

• Train of Four (TOF).
• Stimulate by 4 supramaximal currents.
• TOF ratio > 0.9
• Ratio of 4th stimulus to 1st stimulus
• safe extubation (Fully recovered from muscle relaxant)

Response:

• DMR
• constant diminution.

• NDMR or Phase II of DMR
• gradual fade.

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Phase 2 block

• Succinylcholine >5 mg/kg → receptor damage

• Causes prolonged duration of action

• Rx: Continue Mechanical ventilation

• Resembles NDMR block → Fade present → but Do not give Neostigmine

Site:

• Ulnar nerve,

• adductor pollicis.

Temperature Monitoring

Hypothermia

• Causes:
• Anesthesia → ↓ shivering threshold.
• Depressed hypothalamus,
• chilled OT,
• cold IV fluids.

Hyperthermia

• Causes:
• Malignant hyperthermia,
• sepsis.

Sites

• Note :
• Bladder temperature
• Not performed since values affected by urine flow.

Airway Management & Equipment

Pre-oxygenation

• Normal:
• 100% O₂ via tight mask.
• 10–12 L for 3 min → 10 min apnea time.

• Emergency:
• Preferred:
• 8 Vital Capacity breaths / 1 min.
• Least:
• 4 Vital Capacity breaths / 30 sec.
• Slight heads up position

• Triple maneuver:
• Head tilt + chin lift + jaw thrust.
• To prevent tongue fall back

• Updates:
• THRIVE (Transnasal humidified rapid insufflation)
• 60 L/min for 3 min → ~13 min apnea.
• NO DESAT:
• 15 L/min, directly to pharynx → ~9 min apnea.

• NOTE:
• Tracheal suctioning done after 10 - 15 seconds after 100% Oxygen

• In conventional therapy, the device with highest oxygen delivering capacity is NRBM.

• So the max flow rate through it is 15-16 L/min,.

• Fio2 = 21% +Nasal cannula flow in I/min X 4

Oral & Nasopharyngeal Airways

• Guedel:
• Prevents tongue fall.
• Disadvantage: Gag reflex
• Size: Mouth angle → tragus/mandible angle.

• Nasopharyngeal:
• Prevents pharyngeal collapse.
• CI:
• Adenoids in child,
• base skull fracture,
• coagulopathy.

Laryngoscopy

Position

• “Sniffing the morning air”
• lower cervical flexion +
• atlanto-occipital extension.
• Aligns PA, LA, OA.

• Pillow/head ring
• (10–15 cm).

• Scissor’s method:
• Jaw extension.

Types

Cormack-Lehane Grades

• To assess visibility of glottic opening after laryngoscopy.

• I: Full aperture.

• II: Posterior aperture.

• III: Epiglottis only.

• IV: No epiglottis.

ET Tube

• Adults:
• Narrowest Larynx: Glottis
• Cuff used → Low pressure High Volume ET
• Prevent aspiration.

• Children:
• Narrowest Larynx: Subglottis
• Microcuffed
• Recent recommendation in children after 2020
• Prevent leakage

• Uncuffed.

High Pressure Low Volume:

• Not used now
• Red rubber → >25 cmH₂O → mucosa damage.

Modifications

• Flexometallic/Armored:
• Head & neck Sx
• prone Sx

• Double lumen:
• Lung surgeries.

Ring-Adair-Elwyn (RAE)

• Preformed curvature

• Types
• South facing → cleft lip.
• North facing → lower lip,

Accessories

• Stylet,
• Passed in ETT

• Bougie,
• Direct tracheal insertion

• Magill’s forceps
• For foreign body removal

Advanced

• Flexible Fiberoptic scope:
• Gold standard for knowing exact location of ETT.



• Useful:
• Limited mouth opening,
• lung surgery.
• Capnography → surest intubation sign.

• Video laryngoscope, Airtraq, Bullard.
• Improves HCW protection.

Supraglottic Airway Devices

• Size for Usual 50 - 70 kg person = 4

First Gen – LMA

• Classical (latex).

• Easy, minimal neck movement.

• No aspiration protection.
• Avoid: Emergencies, prone, laparoscopy, pregnancy.

• Anatomy:



• Superior → tongue base.
• Lateral → pyriform fossa.
• Tip → above esophageal sphincter.

• Intubating LMA or Fastrack LMA
• Handle to hold present

• LMA Unique :
• PVC, single use, 1st generation
• Unique among first gen → use PVC

Second Gen – LMA

• Has drain tube.

• LMA Supreme
• PVC
• better seal
• laparoscopic/pregnancy use

• Proseal LMA

• IGEL:
• Silicon gel → take shape of parynx → provide better seal
• So no pilot balloon needed
• Green cap

• Unique, supreme → PVC → fully white transparent

Modifications for Intubation

Manual Inline Stabilisation

• Reduce neck movement (e.g., trauma).

RSI (INICET)

• NOT in Cardiac arrest

• Used in Emergency Surgeries to prevent aspiration

• Preoxygenation
• 3 mins

• Pre Op
• NG Tube
• Metoclopramide
• PPIs
• Antacids like sodium citrate

Sellick’s Maneuver:

Selicks - sealing

Larson’s - Laryngeal

• In RSI

• Cricoid pressure to compress esophagus.

• 30 Newtons

Ramp position:

• Obese airway alignment.

Awake Intubation

• SLN block
• above vocal cords

• Glossopharyngeal block
• posterior tongue, pharynx

• Transtracheal injection
• RLN block (vocal cords).

Failed Intubation Algorithm

• Plan A:
• Facemask + direct laryngoscopy
• Success → intubate.
• Fail → Plan B.

• Plan B:
• Supraglottic Airway insertion
• Success → Stop & think:
1. Wake patient.
2. Intubate via SAD.
3. Proceed without intubation.
4. Tracheostomy/cricothyroidotomy.
• Fail → Plan C.

• Plan C:
• Final facemask ventilation
• Success → Wake patient.
• Fail (CICO) → Plan D.

• Plan D:
• Cricothyroidotomy (last resort)

Difficult intubation