ANAESTHESIA FOR CAESAREAN SECTION

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• ANAESTHESIA FOR CAESAREAN SECTION
• ROLE OF INTRAUTERINE RESUSCITATION

Presenter Dr Neha Gupta Moderator Dr
Geetanjali
University College of Medical Sciences GTB
Hospital, Delhi
www.anaesthesia.co.in
email anaesthesia.co.in_at_gmail.com
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James Young Simpson (1811-1870)
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HISTORY

• 1847 Introduction of inhalational agents
• James Young Simpson on Jan 19, 1847 first used
  chloroform to anaesthetize a woman with a
  deformed pelvis for delivery.
• Early 20th century Expanded use of opioids
• Twilight sleep was a technique developed by
  Von steinbuchel. It combined opioids with
  scopolamine to make women amnesic during labor .
• Mid 20th century (1900-1930) Refinement of
  regional anaesthesia

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INTRODUCTION

• Until 19th Century Performed only for the most
  desperate situations, with very high mortality
  rates.
• Early 20th Century Mortality rates 10, but
  still performed only for the most severe cases of
  contracted pelvis
• In India the caesarean rates have increased from
  21.8 in 1988-89 to 25.4 in 1993-94
• ( Bhasin SK, Rajoura OP, Sharma AK,et al. A high
  prevalence of caesarean
• section rate in East Delhi. Indian J
  Community Med 200732222-4)
•  

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CAESAREAN SECTION

• It is defined as the birth of an infant through
  incision in the abdomen(laparotomy) and
  uterus(hysterotomy).
• (derived from the latin word caedere which imply
  to cut)

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INDICATIONS FOR CAESAREAN SECTION

• Absolute
• Maternal
• Cephalo-pelvic Disproportion
• Non progression of labour
• Fetal
• Fetal Distress
• Non-cephalic presentations
• Multiple gestations
• Pregnancy Related
• Abruptio Placenta
• Grade 3 or 4 Placenta Previa
• Cervical obstructive lesions
• Large vulvar condylomata

• Relative
• Maternal
• Relative CPD
• Maternal preference
• Fetal
• Twins with first in non cephalic presentation
• Pregnancy Related
• Lesser degrees APH
• Previous Caesarean

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COMPLICATIONS OF CS

• Hemorrhage
• Uterine atony
• Uterine laceration
• Broad ligament hematoma
• Infection
• Endometritis
• Wound infection
• Post op complications
• Cardiovascular venous thromboembolism
• Gastrointestinal ileus, adhesions, injury
• Genitourinary bladder or ureter injury
• Respiratory atelectasis , aspiration
• Chronic pain
• Future risk
• Placenta previa,placenta accreta, uterine rupture

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PAIN PATHWAYS

• During Caesarean Section
• Pain due to Incision Pfannensteil / Midline
• Pain due to stretching to the skin and
  subcutaneous tissues
• Intraperitoneal dissection and manipulation
• Additional somatic pain due to diaphragmatic
  stimulation
• Involves dermatomes up to T8 and visceral pain
  pathways up to T4 levels
• Implications Aim is to achieve T4 dermatomal
  level

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• ANAESTHESIA FOR CASEAREAN SECTION
• Techniques of Anaesthesia
• 1. Regional Anaesthesia
• Subarachnoid Block
• Epidural Anaesthesia
• Combined Spinal-Epidural Anaesthesia
• 2. General anaesthesia
• 3. Local anaesthesia

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Anaesthesia for Caesarean Section

• Depends on
• Indication for CS
• Urgency of the procedure
• Maternal and fetal health
• Maternal desires
• If time not a factor RA preferred
• Epidural for Labour Analgesia in-situ
  Extension of Block
• RA contraindicated, or Emergency procedure
  GA

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Classification of caesarean section according to
urgency

• Category 1- requiring IMMEDIATE delivery
• -a threat to maternal or
  fetal life
• Category 2- requiring URGENT delivery
• -maternal or fetal compromise
  that is not
  immediately life threatening
• Category 3- requiring EARLY delivery
• -no maternal or fetal
  compromise
• Category 4-ELECTIVE delivery
• -at time suited to the woman and
  maternity staff

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• Category 1 sections should be delivered within 15
  minutes
• Examples of category 1 include-
• 1.Major haemorrhage
• 2.Profound and persistent fetal bradycardia
• 3.Prolapsed cord
• 4.Shoulder dystocia
• 5.Uterine rupture

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REGIONAL ANAESTHESIA

• Definitive benefits over GA, including
• No risk of aspiration
• No risk of failed intubation or ventilation
• Less blood loss
• Less fetal exposure to drugs
• Better neurobehavioral score of fetus at birth
• Analgesia can be extended to postoperative period

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SPINAL ANAESTHESIA

• SAB most common and preferred technique for CS.
• Advantages of SAB Disadvantages
• Simplicity of technique Limited Duration
• Reliability
• Rapid onset Hypotension
• Dense neural block
• Less shivering Prolonged Motor block
• Minimal fetal exposure to drugs Nausea Vomiting

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EPIDURAL ANAESTHESIA

• Advantages
• Level Titrable
• Slower onset of sympathetic block
• Block height and Duration Extendable
• Less intense motor block
• Post operative analgesia
• Less Chances of DVT

• Disadvantages
• Slow onset of anaesthesia
• Increased failure rates
• Accidental IV injection
• Catheter migration
• Increased chances of total / high spinal
• Technically difficult

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COMBINED SPINAL EPIDURAL ANAESTHESIA

• Rapid and predictable onset of SAB
• Ability to augment anaesthesia
• CSE TECHNIQUES
• Use of conventional doses of hyperbaric drugs
• Sequential CSE technique
• Extradural volume extension (EVE) technique

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COMBINED SPINAL EPIDURAL ANAESTHESIA

• Benefits
• Lower intrathecal dose of LA
• Increased success rates for correct epidural
  placement
• More intense block, less intra operative pain
  compared to epidural
• Disadvantages
• Untested epidural catheter
• Hypotension

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GENERAL ANAESTHESIA

• Indications
• Maternal refusal
• Local site infection
• Raised intracranial tension
• Severe Fetal Distress
• Acute maternal hypovolemia
• Significant coagulopathy
• Inadequate RA/failed RA

• Relative Contraindications
• Anticipated difficult airway
• Malignant hyperthermia
• Severe asthma

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CONSIDERATIONS IN REGIONAL ANAESTHESIA

• Preloading/ co-loading
• Anti aspiration prophylaxis
• Positioning in RA
• Choice of LA
• Choice of vasopressors
• Epidural test dose
• Complications of RA i.e. Nausea and vomiting,
  Hypotension, Accidental intravascular injection
  or dural tap under Epidural anaesthesia, PDPH, LA
  toxicity

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PRELOADING /CO-LOADING

• Preloading- rapid adminisration of crystalloids
  (1-1.5l) prior to initiation of intrathecal
  injection.
• Co-loading- rapid administration of
  crystalloids(20 ml/kg) initiated at the time of
  intrathecal injection.
• Crystalloids/ colloids
• Implication Initiation of anaesthesia should
  not be delayed in order to administer a fixed
  volume of fluid.

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Anti aspiration prophylaxis

• Increased risk of Gastric Aspiration in
  pregnancy
• ? gastric motility
• ? LES tone
• ? gastric emptying time.
• ? Intragastric pressure

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• Antiaspiration Prophylaxis
• Planned CS
• Ranitidine 150 mg and Metoclopramide 10 mg PO
  night before and 60-90 minutes before surgery
• Emergency CS
• 0.3M Sodium Citrate, 30mL PO 30 Min before
  Surgery.
• Ranitidine 50 mg IV Metoclopramide, 10 mg IV
  prior to surgery.

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POSITIONING IN RA

• Minimum left lateral tilt of 25º
• left lateral displacement to be maintained with a
  wedge under the right buttock .

1o cm
34 cm
2.5 cm
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POSITIONS FOR RA

• Lateral position
• better uteroplacental blood flow
• more comfortable
• minimises patient movement during needle
  insertion

• Sitting position
• Distance from skin to epidural space is shorter
• Interspinous spaces difficult to appreciate
• Restricted use i.e. umbilical cord prolapse,
  footling presentation.

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CHOICE OF LOCAL ANAESTHETIC FOR SAB
Drug Dosage (mg) Range (ml) Duration (min)
Bupivacaine(H) (0.5) 7.5-15 1.5-3 60-120
Ropivacaine 15-25 60-120
Lidocaine(H) (5 ) 60-80 1.2-1.5 45-75
chestnuts obstetric anaesthesia (4th edition)
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Local anaesthetics for epidural anaesthesia

Drug Dose range Duration(min)
Bupivacaine 0.5 75-125 mg 120-180
Ropivacaine 0.5 75-125 mg 120-180
Lignocaine 2 with epinephrine 5µg/ml 300-500 mg 75-100
chestnuts obstetric anaesthesia (4th edition)
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• DECREASE IN LOCAL ANAESTHETIC REQUIREMENT DURING
  PREGNANCY
• 1.? Neural susceptibility to LA
• 2. Epidural plexus engorgement
• 3. CSF changes a)?CSF protein (?unbound drug)
• b)? CSF pH (?
  unionised drug)
• 4. Apex of thoracic kyphosis higher
• 5.Pelvic widening resultant head down tilt in
  lateral position

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Pelvic widening resultant head down tilt
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Adjuvant agents

• ADVANTAGES
• Improves the quality of intraoperative
  anaesthesia
• Prolongs the postoperative analgesia
• Reduce the dose of LA and thus the side effects

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ADJUVANTS
DRUG DOSAGE Range(ml) Duration(min)
Fentanyl (5o µg/ml) 10-25 µg 0.2-0.5 180-240
morphine 0.1-0.25 mg 720-1440
Sufentanyl 2.5-5µg 180-240
Midazolam 1-2 mg
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Side effects OF OPIOID ADJUVANTS

• Pruritis
• Delayed respiratory depression
• Nausea and vomiting
• Urinary retention
• Reactivation of varicella zoster

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Spinal Needles
Quincke type Spinal Needles
Whitacre type Spinal Needles
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CHOICE OF VASOPRESSORS

• Ephedrine
• mixed alpha and beta adrenergic receptor agonist
• Increase blood pressure without a decrease in
  uterine blood flow
• DOSE 10 mg prophylaxis
• 5- 10 mg therapeutic
• S/E
• Tachyphylaxis
• Can lower umbilical cord pH by
• 1.Readily cross placenta cause fetal tachycardia
• 2. Stimulate fetal metabolism by direct
  b-adrenergic effect
• maternal tachycardia

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• Phenylephrine (first line agent)
• alpha-receptor agonist
• Equally effective as ephedrine
• better umbilical cord pH
• better preserves uterine blood flow
• Dose 50- 100 µg
• S/E - maternal bradycardia

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Why phenylephrine?

• Does not have beta adrenergic agonist action thus
• No beta adrenergic action in fetus and thus
  better maintain fetal metabolism
• Least chances of fetal acidosis or hypoxia, as
  reflected by better maintained umbilical cord pH.

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EPIDURAL TEST DOSE

• Role To check the intrathecal and intravascular
  placement of epidural catheter
• 3 ml LA 15µg Epinephrin (1200,000)
• Response - ?HR- 30 bpm, ?SBP 20 mmHg in 45 sec.
• Test dose is less specific in labouring patients
• Points against routine use
• Aspiration of multiorifice catheter is 98
  sensitive
• Low concentration of LA
• Recommended 2 stage safety check is ASPIRATE and
  OBSERVE FOR 5 MIN.

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RECOMMENDED SAFETY PROCEDURE BEFORE INJECTION OF
TEST DOSE

• Perform aspiration test
• In labour- 2 ml of 1.5- 2 LA with out ADR
• For C.S 3 ml of 1.5- 2 LA with 15µg (1
  200,000) ADR
• In PIH, IUGR, DM or Fetal distress Bupivacaine
  in 5 ml increments
• Test dose failure or Total spinal block Treat
  promptly
• Prince G et al Obstetric epidural test
  dose. A reappraisal. Anaesthesia 1986.

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Regional Anaesthesia Complications

• HYPOTENSION
• Def ? in SBP of more than 20-30 from baseline
• OR a SBP lower than 100 mm hg.
• Prevention
• Left uterine displacement
• Prehydration
• Prophylaxis with vasopressor
• Leg elevation or wrapping
• Treatment i.v fluids
• vasopressors

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Regional Anaesthesia Complications

• NAUSEA AND VOMITING
• CAUSES
• 1.Hypotension
• hypotension
• Gut ischemia
  brain stem hypoperfusion
• Release of emetogenic Stimulation of vomiting
• Substance Centre
• Vomiting
• 
  

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• 2. Increased vagal activity
• 3. Surgical stimuli- exteriorisation of uterus
• 4. Bleeding
• 5. Drugs ureterotonic agents
• Treatment
• Prevention of hypotension
• Metoclopramide
• Ondansetron

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Regional Anaesthesia Complications

• Post Dural Puncture Headache
• Risk factors
• Agelt40
• Women
• Pregnancy
• Use of wider guage and dura cutting spinl needle.
• Symptoms
• Frontal / Occipital headache
• Positional
• Varying severity
• Neck Stiffness
• Ocular or Auditory symptoms
• Onset within 48 hours

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Regional Anaesthesia Complications

• Pathophysiology
• Treatment
• Early Psychological support
• prevent dehydration
• Drugs NSAIDs, Caffeine, Sumatriptan
• Epidural Saline Patch
• Epidural Blood Patch-15-20 mL autologous blood
  used.

Leakage of CSF
Traction on pain sensitive structures
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Regional Anaesthesia Complications

• High Spinal Anaesthesia
• Rostral spread of intrathecal dose, or
  Inadvertent intrathecal administration of
  epidural dose
• Clinical Features
• Complete motor and sensory palsy,
• Hypotension, Bradycardia,
• Unconsciousness,
• Loss of protective airway reflexes,
• respiratory arrest
• Treatment Prompt tracheal intubation and
  ventilation with 100 oxygen, maintenance of
  maternal circulation

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Regional anaesthesia Complications

• ACCIDENTAL DURAL PUNCTURE
• Incidence-3 (in obstetric patients)
• Steps to be followed in case of accidental dural
  puncture
• 1.Injection of CSF from the epidural syringe back
  into the SAS through epidural needle
• 2.Insertion of epidural catheter into the SAS
• 3.Injection of NS through intrathecal catheter
  before removal
• 4.Administration of continous intrathecal labour
  analgesia
• 5.Leaving the intrathecal catheter in situ for a
  total of 12-20 hours
• Kuczkowski K M et.al. Acta Anaesthesiol scand
  2003

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Regional Anaesthesia Complications

• LA toxicity
• IV injection of LA.
• Bupivacaine most cardiotoxic,
• Toxicity enhanced in pregnancy.
• Clinical Features Convulsions, Arrhythmias
• Cardiovascular
  collapse
• Treatment for CNS Symptoms-symptomatic
• oxygen supplementation
  ,tracheal intubation
• Prevention Epidural test dose with adrenalin
  15µg.

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ROLE OF INTRALIPID

• Role - local anesthetic-induced cardiac arrest
  that is unresponsive to standard therapy, in
  addition to standard cardio-pulmonary
  resuscitation
• Mechanism . may serve as a lipid sink,
  providing a large lipid phase in the plasma,
  enabling capture of the local anaesthetic
  molecules and making them unavailable to
  tissues.-
• Dose regime
• Intralipid 20 ,1.5 mL/kg i.v over 1 minute
  ,followed by 0.25 mL/kg/min,
• Repeat bolus every 3-5 minutes up to 3 mL/kg
  total dose until
• circulation is restored
• Maximum dose - 8 mL/kg

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Case 1

• 24 yr old, primigravidae, ASA grade I, with
  complaints of
• Amenorrhea for 9 months
• Leaking per vaginum for 2 hours
• Pain abdomen for 2 hours
• Obstetric history- WNL
• GPE WNL
• Plan - Emergency LSCS in view of cephalopelvic
  dispropotion in labour.

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• Single shot spinal anaesthesia
• PATIENT PREPARATION
• Preanaesthetic evaluation history
• 
  -clinical examination
• Fasting was 8 hours.
• Informed consent taken
• Inj Ranitidine (50 mg i.v.), Inj
  metoclopramide(10 mg i.v.) 30 min prior to
  surgery
• Monitoring i.e.ECG, NIBP ,Pulse oximetry.
• Coloading 1.5 l ringer lactate
• Positioning Left lateral Displacement
  maintained with a Wedge under right buttock.

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• Sitting position
• 25 G quincke needle in L3-L-4 space
• 10 mg(2 ml) of 0.5bupivcaine H
• T4 level achieved .
• Oxygen by face mask to provide an Fio2 0.5 -0.6
• No hypotension reported.
• Pfannensteil Incision made, baby delivered
  within 15 min.
• Injection oxytocin (5U i.v. f/b 15 U slow i.v.
  in 500 ml RL)
• I/O - No complications.
• Post op level T6

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• ANAESTHESIA FOR CAESAREAN SECTION
• ROLE OF INTRAUTERINE RESUSCITATION
• MODERATOR DR GEETANJALI

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• GENERAL ANAESTHESIA

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GA associated mortality

• Pulmonary aspiration- 1 400-500 versus 1 2000
• Failed tracheal intubation 1 300 versus 1 2000

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CONSIDERATIONS IN GA

• Airway assesment
• Positioning
• Anti-aspiration prophylaxis
• Preoxygenation
• RSI
• Skin incision uterine incision time, Uterine
  incision baby delivery time
• Uterotonic agents
• Exterioratization of uterus
• Complications i.e. Awareness,Aspiration,Difficult
  airway, altered neonatal outcome, hypotension and
  others

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• WHY DIFFICULT AIRWAY?

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WHY DIFFICULT AIRWAY?

• Risk factor for airway complication in pregnancy
• Airway edema
• Weight gain
• Enlarged breast
• Full dentition
• Decreased LES tone
• Reduced gastric emptying during labour
• Rapid desaturation due to Increased oxygen
  consumption and reduced FRC.

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AIRWAY ASSESSMENT

• 1.Mallampatti classification
• 2.Atlanto occipital joint extension
• 3.Thyromental distance
• 4. Mandibular protrusion test
• Benumofs 11 point sytem for evaluation of airway

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AIRWAY ASSESSMENT

• 1.Mallampatti classification
• 2.Atlanto occipital joint extension
• 3.Thyromental distance
• 4. Mandibular protrusion test
• Benumofs 11 point sytem for evaluation of airway

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CONSIDERATIONS IN GA

• Airway assesment
• Positioning
• Anti-aspiration prophylaxis
• Preoxygenation
• RSI
• Skin incision uterine incision time, Uterine
  incision baby delivery time
• Uterotonic agents
• Exterioratization of uterus
• Complications i.e. Awareness, hypotension,
  Uterine atony, Blood loss, PONV, Difficult airway.

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POSITIONING
60

• RAMP POSITION in morbidly obese patients
• -ideal position leads to horizontal alignment
  between the external auditary meatus and sternal
  notch
• -achieved by use of blankets or commercially
  available devices

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Commercially available RAMP
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CONSIDERATIONS IN GA

• Airway assessment
• Positioning
• Anti-aspiration prophylaxis
• Preoxygenation
• RSI
• Skin incision uterine incision time, Uterine
  incision baby delivery time
• Uterotonic agents
• Exterioratization of uterus
• Complications i.e. Awareness, Pulmonary
  aspiration, Neonatal depression PONV, Difficult
  airway, hypotension, Uterine atony, Blood loss,

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Conduct of general anaesthesia

• Preparation in OT
• Machine check
• Difficult Airway cart with short handle
  laryngoscopes
• Oropharyngeal airway
• One extra styletted endotracheal tube
• Magill forcep
• Laryngeal mask airway
• Intubating Laryngeal mask airway
• Trained assistant to be available
• Fiberoptic bronchoscope
• Verify that surgeons are ready to begin the
  surgery

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Conduct of General anaesthesia

• Preoxygenation
• Aim increase in oxygen content and maximise the
  time to desaturation.
• 1. conventional method normal tidal volume for
  3 minutes
• 2. 4 vital capacity breaths over 30 seconds(In
  emergency)
• 3. 8 vital capacity breaths over one minute.
• Rapid Sequence Induction
• Thiopental 4-5 mg/kg
• Continued application of Cricoid Pressure (10 N
  when awake,increase to 30N after loss of
  consciousness.)
• Succinylcholine 1-1.5 mg/kg wait for 30-40
  seconds.

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• Why Rapid Sequence Induction?

66

• Recommended technique for General Anaesthesia
• Problem-
• Difficult laryngoscopy and failed
  intubation in group of patients who are already
  at risk of rapidly developing hypoxemia

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Conduct of Anaesthesia - General Anaesthesia

• Sellicks Manoeuvre
• Dedicated Assistant
• 20-30 N (2-3 Kg) Force
• Directed backwards
• Continued till airway secured and cuff is
  inflated

68
INTRAVENOUS AGENTS
AGENT FM CLINICAL IMPLICATIONS REMARKS
THIOPENTONE 0.4 to 1.1 Freely diffusible. Prompt and reliable induction. Fetal brain levels lt levels enough to cause depression Popular agent of choice No analgesic and amnesic effects.
PROPOFOL 0.65 to 0.85(bolus 2 to 2.5 mg/kg) 0.50 to 0.54 (inf _at_ 6-9 mg/kg/hr) FDA category B drug may attenuate the response to laryngoscopy and intubation UBF no change Sedative effect on neonate Lower 1 and 5 min apgar scores (2.8 mg/kg)
KETAMINE ETOMIDATE 1.26( in 1.5 min) Used in hypotension and asthma Rapidly crosses placenta
Used in hemodynamic instability
0.5
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Conduct of Anaesthesia - General Anaesthesia

• Maintenance of Anaesthesia
• GOALS
• Adequate maternal and fetal oxygenation
• Maintain maternal normocapnia (avoid
  hyperventilation as it may lead to uteroplacental
  vasoconstriction)
• Appropriate depth to avoid awareness , promote
  maternal comfort
• Minimal effect on uterine tone.
• Minimal adverse effect on neonate.
• MONITORING - ASA recommended minimal mandatory
  monitors

70

• Pre-delivery O2N20 5050 1 MAC Inhalational
  agent
• Post-delivery
• O2N2O 3070
• Reduction of Inhalation agent(0.5-0.75 MAC)
• Morphine 0.1 mg/kg or Fentanyl 1-2 µg/kg.
• Extubation done when neuromuscular blockade
  fully reversed and patient is awake and responds
  to command.

71
I-D TIME AND U-D TIME

• Induction delivery(I-D) time - less than 15
  minutes
• Uterine-delivery (U-D) interval- less than 90
  seconds
• Implication Abdomen preparation and draping
  should be done before induction of anaesthesia

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UTEROTONIC AGENTS

• 1.Oxytocin infusion
• Route i.v.
• Side effects hypotension ,tachycardia, water
  intoxication
• Bolus injection ? Maternal tachycardia
  Hypotension
• Dose 200 Mu/min
• 2.Methylergometrin
• Route i.m /i.v.
• Side effect Severe Hypertension, bradycardia
• Dose 0.2 mg

73

• 3.PGF2 alpha (carboprost)
• Route i.m. /intramyometrial
• Side Effects Nausea, Vomiting, diarrhoea,
  Fever, Tachycardia, Hypertension,
  Bronchoconstriction
• Contraindication Bronchial Asthma
• Dose - 250 µg
• Max Dose 2gm

74
EXTERIORISATION OF UTERUS

• Increase the incidence of nausea and vomiting
• Cause a tugging sensation
• Require a higher level of dermatomal block

75
Complication of general anaesthesia

• AWARENESS AND RECALL
• Causes
• 1.Avoidance of sedative premedication
• 2.Deliberate use of low concentration of volatile
  anaesthetic agent
• 3.Use of muscle relaxant
• 4.Reduction in dose of anesthetic agent during
  hypotension
• 5.The mistaken assumption that high baseline
  sympathetic tone is responsible for
  intraoperative tachycardia.

76

• Role of Depth of Anaesthesia monitoring i.e. BIS
• BIS is an empirically derived EEG parameters
• VALIDATED to greater extent
• Desired value less than 60
• Reduces but can not prevent awareness episodes

77

• How to avoid
• Lyons and Macdonald recommend-
• Larger induction dose of barbiturate(thiopental
  5-7 mg/kg)
• Isoflurane 1 prior to delivery
• After delivery administration of opioid and
  decrease conc .of isoflurane
• For RA
• Midazolam 0.075 mg/kg provide 30-60 min of
  anterograde amnesia in RA
• ( Lyons G ,Macdonald R. Awareness during
  caesarean section. Anaesthesia 1991)

78
Complications of general anaesthesia

• ASPIRATION PNEUMONITIS
• First Described by Mendelson in 1946.
• Chemical injury to tracheobronchial tree and
  alveoli caused by inhalation of sterile acidic
  gastric contents.
• RISK FACTORS
• Gastric Volume gt 25mL
• Gastric pH lt 2.5
• Predisposing Factors
• Impaired LES tone
• Impaired laryngeal reflexes
• Altered gastric motility
• Absence of pre-operative fasting

79
Aspiration Pneumonitis

• Pathophysiology

Epithelial Degeneration Interstitial Alveolar
Oedema Haemorrhage into alveoli
ARDS Pulmonary oedema
Aspiration of Acidic Contents
Destruction of Pneumocytes
Decreased Surfactant
Hyaline membrane Formation
V/Q mismatch
Destruction of Microvasculature
Increased Pulmonary Vascular Resistance
Increased Vd/Vt
80
Aspiration Pneumonitis

• Diagnosis
• Time of presentation variable ? First 24 Hours
• History of predisposing factors
• Wheeze laboured breathing
• Progresses to ARDS and Pulmonary Oedema
• CXR Changes with Hypoxemia Suspect Silent
  Aspiration
• CXR B/L fluffy interstitial shadows

81
Aspiration Pneumonitis

• Treatment
• Mild ? Nebulisation, Oxygen Inhalation
• Severe ? Prompt intubation Tracheal Suctioning
  before Positive pressure ventilation
• PEEP, CPAP ?To maintain oxygenation
• Mech. Ventilation ? Low tidal volume (6mL/kg) and
  Plateau Pressure lt30 cm H20
• Fluids CVP guided
• Antibiotics- not efficaceous, can lead to
  infection by resistant organisms.
• Steroids- not recommended

82

• Prevention - Antiaspiration Prophylaxis
• Planned CS
• Ranitidine 150 mg and Metoclopramide 10 mg PO
  night before and 60-90 minutes before surgery
• Emergency CS
• 0.3M Sodium Citrate, 30mL PO 30 Min before
  Surgery.
• Ranitidine 50 mg IV Metoclopramide, 10 mg IV
  prior to surgery.

83

• Fasting guidelines (ASA recommendations)
• Clear liquids uncomplicated patients for c.s.
  can have clear liquid upto 2 hours before
  induction of anaesthesia
• Solids - solid food to be avoided in labouring
  patients
• - In elective surgery fasting
  should be 6-8 hours
  depending on the fat content

84
Complications of general anaesthesia

• HYPOTENSION most important cause-
• Induction agents-intravenous
• -inhalational
• Use of oxytocin
• Major Blood loss /PPH
• Treatment
• using the induction agent in appropriate doses
• use of vasopressors as previously discussed
• active management of PPH

85
Complications of general anaesthesia

• UTERINE ATONY
• Causes
• High parity
• Overdistended uterus
• Prolonged labour
• Abnormal placentation hypotension
• Treatment
• Oxytocin(200mU/ min)
• Methylergometrine(0.2 mg i.m.)
• Prostaglandin F2a (250 µg i.m.)

86
Complications of general anaesthesia

• POST OP NAUSEA AND VOMITING
• Risk factors
• Female gender
• History of motion sickness
• Use of perioperative steroids
• Non smoking status

87
Drugs used for prevention
Drug Dose Time
Metoclopramide 10 mg i.v. Prior to surgery or after cord clamping
Ondansetron 4 mg i.v. After cord clamping
Granisetron 40mcg/kg i.v. After cord clamping

88
CASE 2

• 22 yr primigravidae, ASA grade I, planned for
  emergency LSCS in view of cord prolapse with
  fetal distress
• Obstetric history -WNL
• GPE WNL
• Airway assessment- Mouth opening adequate
• -MPG 2
• -Neck
  movements-normal
• -TMD - WNL

89

• Informed consent taken
• Inj ranitidine(50 mg i.v.), inj .metoclopramide
  (10 mg i.v.)
• Necessary equipment prepared, monitors attached
• preoxygenation with 100 oxygen
• Abdomen cleaned and draped side by
  side
• RSI with cricoid
  pressure,
• 4mg/kg thiopentone,
• confirm ventilation
  
• Succinylcholine 1.5 mg/kg,
  
• Laryngocopic view of glottis (Cormack Lehane
  GRADE III)
• Failed tracheal intubation(2 attempts
  with change of blade, use of styletted ET tube
  and change of hand)

90
Management of Failed Intubation in
Pregnant Patients
Failed Intubation

• Call for help
• Ventilate with 100 Oxygen
• Facemask with cricoid pressure OR
• LMA and cricoid pressure

Assess Ventilation and Oxygenation
Adequate
91
Assess Fetus
Fetal Distress
No Fetal Distress
Mask with cricoid pressure
Surgical Airway
Awaken Patient
Regional
Intubate
Succeed
Fail
Fail
Succeed
Extubate over Jet Stylet
92
Rosens Modification of Tunstall Drill (Failed
Intubation Drill)
1.Maintain Cricoid Pressure Place the patient
Left lateral, Head Down.
2.Maintain oxygenation by IPPV with 100 oxygen
If difficult- Try change in position,
oropharyngeal airway or 2 person mask
ventilation
3.If airway obstruction persists, Release cricoid
pressure.
4. If ventilation oxygenation easy, ventilate
with oxygen, nitrous oxide And halogenated
agent. Proceed with surgery with face mask
ventilation Allow resumption of spontaneous
ventilation
5.Aspirate gastric contents instil
nonparticulate antacid with Orogastric tube.
Withdraw tube while suctioning oropharynx.
6.Level table. Place patient supine. Allow
surgery to continue with Inhalational
anaesthesia. Expert paediatrician must be present.
93
Management of Failed Intubation in
Pregnant Patients
Failed Intubation

• Call for help
• Ventilate with 100 Oxygen
• Facemask with cricoid pressure OR
• LMA and cricoid pressure

Assess Ventilation and Oxygenation
Inadequate
CVCI

• Consider Non surgical Airway
• LMA with Cricoid Pressure OR
• Combitube OR
• TTJV

• Surgical Airway
• Cricothyrotomy OR
• Tracheostomy

Deliver Baby
94

• Parturients die of desaturation rather than
  not being able to intubate

95
Use of PLMA in obstetrics

1. As a rescue device in cases where conventional
   mask ventilation is difficult/ impossible.
2. As a conduit for intubation in case of difficult
   intubation.
3. To facilitate fibreoptic intubation with
   bronchoscope.
4. Role in Elective casesarean delivery - yet to be
   established

96

• Han TH, Briamacombe J et al. The Classic
  laryngeal mask airway is effective and probably
  safe in selected healthy parturients for elective
  caesarean delivery A prospective study of 1067
  cases. Can J Anesth 2001.
• Conclusion LMA is effective and probably safe
  for Casearean section in healthy selected
  parturients when managed by experienced LMA user

97

• Halaseh RK, et al. The use of PLMA in casearean
  section experience in 3000 cases. Anesth
  Intensive Care 2010
• Conclusion
• PLMA
• Selected patients
• METHOD OF INSERTION
• No aspiration
• Good alternative to TT

98

• Disadvantages
• Placement can induce vomiting, laryngospasm
• Aspiration of gastric contents is not prevented.
• Improper positioning can lead to gastric
  insufflation
• Use of PPV may be limited.
• Multiple insertion attempts may lead to airway
  trauma.
• However, use of PLMA avoid these disadvantages
  to an extent

99
Intrauterine fetal resuscitation

• 1. Optimise maternal position
• Relieve aortocaval compression
• Relieve umbilical cord compression
• 2. Administer supplemental oxygen
• 3. Maintain maternal circulation
• Rapid administratiom of i.v. fluids
• Use of vasopressors to treat hypotension
• . In case of uterine tachysystole or hypertonus
• Administration of tocolytic
• Use of nitroglycerin (50-100 µg i.v.) provide
  uterine relaxation in 40-45 seconds .

100
KEY POINTS

• During pregnancy LES tone is ?, gastric motility
  ? - Increased risk of aspiration
• The gastrointestinal changes persist 36 hours
  post delivery
• Role of supplemental oxygen during RA -in non
  compromised fetus questionable
• Left uterine displacement essential ,
  irrespective of technique used
• Umbilical cord prolapse without fetal distress-
  not an absolute indication of GA

101

• The combination of aspiration, test dose and
  fractionation of dose increases the safety
• Cricoid pressure can increase the C/ L grading by
  1
• End tidal MAC requirement of IAA to be maintained
  to 1 to prevent maternal awareness and uterine
  relaxation
• While choosing IAA, must consider reduced MAC in
  obstetric patients as well as the potential for
  maternal awareness and uterine relaxation

102
REFERENCES

• Obstetric Anaesthesia, Principles and Practice,
  David H Chestnut, 4th Ed
• Millers Anesthesia, 7th Ed
• Wylie and Churchill Davidsons A Practice of
  Anaesthesia, 7th Ed
• Barash Stolting Anaesthesia
• Morgans Anaesthesia.

103
www.anaesthesia.co.in
104
anticipated difficult airway
avoid airway manipulation
Accept airway manipulation
labour
Caesarean delivery
airway preparation
vv
elective
emergency
CSE LEA CSA
Awake laryngoscopy Awake fob intubation Awake
tracheostomy
SPINAL LEA CSE CSA
SPINAL CSE CSA
105
Conduct of Anaesthesia - General Anaesthesia

• Inducing Agents Thiopentone Sodium, Ketamine,
  Propofol.
• Thiopentone Sodium
• Most popular. Safe
• Prompt and reliable induction
• No airway irritability.
• Dose 4-5mg/kg
• Crosses placenta.
• Peak UV conc. In 1 minute
• UAUV ratio 0.87 at I-D interval 8-22 min
• Fetal brain levels lt levels enough to cause
  depression
• Disadvantage
• No analgesic and amnesic effects.

106

• Propofol
• Controversial
• Rapid smooth induction, rapid awakening.
• Dose 2-2.5mg/kg
• FM ratio at Delivery 0.7
• Neonatal Apgar scores and neurobehavioral scores
  lower in propofol group compared to
  Thiopentone(Celleno et al)
• Greater incidence of maternal hypotension may
  attenuate the response to laryngoscopy and
  intubation
• More expensive, provide vehicle for bacterial
  growth

107

• Ketamine
• Rapid onset. Has sympathomimetic action.
• Better in Asthma and hypovolemia
• Provides analgesia, amnesia and hypnosis
• Dose 1mg/kg.
• 100 oxygen can be administered
• Disadvantages
• Increases laryngoscopy and intubation response,
• myocardial depression

108

• Muscle Relaxants
• Succinyl Choline
• Dose-1-1.5mg/Kg
• Optimal intubation time of 45 Sec
• Minimal placental transfer
• Rocuronium
• Dose 0.6mg/kg (Intubation time 98 sec)
• 0.9-1.2 mg/kg (48 sec)
• Duration of action prolonged Anticipated
  difficult airway
• Vecuronium
• Dose0.1 mg/kg(onset time -144 sec)
• Used when scholine is contraindicated