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ANAESTHESIA FOR CAESAREAN SECTION ROLE OF INTRAUTERINE RESUSCITATION

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1 ANAESTHESIA FOR CAESAREAN SECTION ROLE OF INTRAUTERINE RESUSCITATION
Presenter: Dr Neha Gupta Moderator: Dr Geetanjali University College of Medical Sciences & GTB Hospital, Delhi

2 James Young Simpson (1811-1870)

3 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 ( ): Refinement of regional anaesthesia

4 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 to 25.4% in * (* Bhasin SK, Rajoura OP, Sharma AK,et al. A high prevalence of caesarean section rate in East Delhi. Indian J Community Med 2007;32:222-4)

5 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)

6 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

7 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 Before we proceed to the anaesthetic management, we must know the complications associated with the procedure

8 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

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

10 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 The surgical indication and therefore the speed of delivery. Anaesthetic considerations include the presence of an epidural catheter, the anticipation of difficult airway, contraindications to regional techniques or potential technical difficulties like spinal deformity and maternal preference. If time not a factor, RA is preferred for both planned and semi emergency situations Emergency cases without anticipated difficult airway, SAB is given If Epidural catheter for labour analgesia in situ, block extended to levels adequate for caesarean In Fetal Distress, Subarachnoid block is safe. Even if hypotension occurs, fetal circulation isn’t compromised If speed of delivery is of essence, RA is contraindicated or in severe maternal haemorrhage GA is administered.

11 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

12 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

13 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

14 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

15 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 The use of epidural anaesthesia for C.S has increased as a result of greater use of epidural analgesia during labour. Shivering increases oxygen demand, cardiac work and co2 production.

16 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

17 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 Hypotension is due to delay in making the patient supine from sitting position and enhanced spread of intra thecal LA following epidural injection

18 Relative Contraindications:
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

19 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 Before we move to the conduct of RA or GA , we would like to discuss the considerations under RA or GA

20 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. Role of i.v fluids: decrease the frequency of neuraxial anaeshesia associated hypotension. A balanced salt solution – ringer lactate is preferred

21 Anti aspiration prophylaxis
Increased risk of Gastric Aspiration in pregnancy ↓ gastric motility ↓ LES tone ↑ gastric emptying time. ↑ Intragastric pressure

22 Antiaspiration Prophylaxis: Planned CS:
Ranitidine 150 mg and Metoclopramide 10 mg PO night before and 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. Na citrate does not dercrease the volume and dose need to be repeated if the surgery is prolonged .

23 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

24 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. Stands controversial

25 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 Lidocaine(H) (5% ) 60-80 45-75 choice of LA depend on the expected duration of surgery, post operative analgesia and preference of the anaesthetist. Bupivacaine is the DOC , LIGNOCAINE IS ASSOCIATED WWITH TNS. Ropivacaine is 40% less potent with less duration of sensory and motor blockade. chestnut’s obstetric anaesthesia (4th edition)

26 Local anaesthetics for epidural anaesthesia
Drug Dose range Duration(min) Bupivacaine 0.5% mg Ropivacaine 0.5% Lignocaine 2% with epinephrine 5µg/ml mg 75-100 chestnut’s obstetric anaesthesia (4th edition)

27 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

28 Pelvic widening & resultant head down tilt

29 Adjuvant agents ADVANTAGES
Improves the quality of intraoperative anaesthesia Prolongs the postoperative analgesia Reduce the dose of LA and thus the side effects DEFINITIONS

30 ADJUVANTS DRUG DOSAGE Range(ml) Duration(min) Fentanyl (5o µg/ml)
morphine mg Sufentanyl 2.5-5µg Midazolam 1-2 mg SUFENTANYL, NEOSTIGMINE, MIDAZOLAM

31 Side effects OF OPIOID ADJUVANTS
Pruritis Delayed respiratory depression Nausea and vomiting Urinary retention Reactivation of varicella zoster

32 Spinal Needles Quincke type Spinal Needles
Whitacre type Spinal Needles

33 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

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

35 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.

36 EPIDURAL TEST DOSE Role – To check the intrathecal and intravascular placement of epidural catheter 3 ml LA + 15µg Epinephrin (1:200,000) 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. Epidural test dose is imp in obstetric patients as the incidence of accidental intravascular puncture is high. IN LABOUR LESS SPECIFIC as cyclic changes in maternal heart rate complicates its interpretation , test dose immediately after contractions.

37 RECOMMENDED SAFETY PROCEDURE BEFORE INJECTION OF TEST DOSE
Perform aspiration test In labour- 2 ml of % LA with out ADR For C.S – 3 ml of % 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.

38 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

39 Regional Anaesthesia – Complications
NAUSEA AND VOMITING CAUSES – 1.Hypotension hypotension Gut ischemia brain stem hypoperfusion Release of emetogenic Stimulation of vomiting Substance Centre Vomiting

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

41 Regional Anaesthesia – Complications
Post Dural Puncture Headache Risk factors: Age<40 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 Post Dural Puncture Headache Frontal or Occipital headache. Severity varies – Mild to debilitating. Symptoms worse when upright. Relieved in supine. Onset in first 48 hours. Last less than a week

42 Regional Anaesthesia – Complications
Pathophysiology Treatment: Early: Psychological support prevent dehydration Drugs: NSAIDs, Caffeine, Sumatriptan Epidural Saline Patch Epidural Blood Patch mL autologous blood used. Leakage of CSF Traction on pain sensitive structures 2 people will wash up. Sumatirptan is a serotonin agonist with cerebral vasoconstrictor action. Given s/c

43 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

44 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 hours *Kuczkowski K M et.al. Acta Anaesthesiol scand :2003

45 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.

46 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

47 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.

48 PATIENT PREPARATION Single shot spinal anaesthesia
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.

49 Sitting position 25 G quincke needle; in L3-L-4 space ; 10 mg(2 ml) of 0.5%bupivcaine H T4 level achieved . Oxygen by face mask to provide an Fio 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

50 ANAESTHESIA FOR CAESAREAN SECTION ROLE OF INTRAUTERINE RESUSCITATION
MODERATOR: DR GEETANJALI

51 GENERAL ANAESTHESIA

52 GA associated mortality
Pulmonary aspiration- 1: versus 1: 2000 Failed tracheal intubation – 1: 300 versus 1: 2000

53 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

54 WHY DIFFICULT AIRWAY?

55 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.

56 AIRWAY ASSESSMENT 1.Mallampatti classification 2.Atlanto occipital joint extension 3.Thyromental distance 4. Mandibular protrusion test Benumof’s 11 point sytem for evaluation of airway

57 AIRWAY ASSESSMENT 1.Mallampatti classification 2.Atlanto occipital joint extension 3.Thyromental distance 4. Mandibular protrusion test Benumof’s 11 point sytem for evaluation of airway

58 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.

59 POSITIONING Correct positioning to maximise the chance of succesful intubation

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 improve oygenation and laryngoscopic view of glottis

61 Commercially available RAMP

62 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,

63 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

64 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) 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 mg/kg; wait for seconds.

65 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

67 Conduct of Anaesthesia - General Anaesthesia
Sellick’s Manoeuvre: Dedicated Assistant 20-30 N (2-3 Kg) Force Directed backwards Continued till airway secured and cuff is inflated

68 CLINICAL IMPLICATIONS
INTRAVENOUS AGENTS AGENT F:M CLINICAL IMPLICATIONS REMARKS THIOPENTONE 0.4 to 1.1 Freely diffusible. Prompt and reliable induction. Fetal brain levels < 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 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

69 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 Post-delivery: Pre-delivery: O2:N20 50:50 + 1 MAC Inhalational agent
O2:N2O :: 30:70 Reduction of Inhalation agent( 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

72 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 20U to 500mL makes 40U/mL. Ideally, it should run at 1-2 mL/Min

73 3.PGF2 alpha (carboprost)
Route : i.m. /intramyometrial Side Effects: Nausea, Vomiting, diarrhoea, Fever, Tachycardia, Hypertension, Bronchoconstriction Contraindication: Bronchial Asthma Dose 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 For RA: 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 mg/kg provide 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 > 25mL Gastric pH < 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 Aspiration of Acidic Contents ARDS & Pulmonary oedema 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 <30 cm H20 Fluids : CVP guided Antibiotics- not efficaceous, can lead to infection by resistant organisms. Steroids- not recommended No role for prophylactic antibiotics If used, should be either guided by culture reports of tracheobronchial aspirate, or broad spectrum empirical antibiotics with gram negative coverage No role for steroid, though they are used 81

82 Prevention - Antiaspiration Prophylaxis: Planned CS:
Ranitidine 150 mg and Metoclopramide 10 mg PO night before and 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. Na citrate does not dercrease the volume and dose need to be repeated if the surgery is prolonged .

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 F2α (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
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.

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 Ventilate with 100% Oxygen Facemask with cricoid pressure OR
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 Intubate Regional Fail Succeed Fail Succeed Extubate over Jet Stylet

92 Rosen’s 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 CVCI Management of Failed Intubation in Pregnant Patients
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
As a rescue device in cases where conventional mask ventilation is difficult/ impossible. As a conduit for intubation in case of difficult intubation. To facilitate fibreoptic intubation with bronchoscope. Role in Elective casesarean delivery - yet to be established

96 Han TH, Briamacombe J et al
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 ( µg i.v.) provide uterine relaxation in 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 Miller’s Anesthesia, 7th Ed Wylie and Churchill Davidson’s A Practice of Anaesthesia, 7th Ed Barash & Stolting Anaesthesia Morgan’s Anaesthesia.

103

104 anticipated difficult airway
avoid airway manipulation Accept airway manipulation labour Caesarean delivery airway preparation vv CSE LEA CSA elective emergency 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 UA:UV ratio 0.87 at I-D interval 8-22 min Fetal brain levels < levels enough to cause depression Disadvantage: No analgesic and amnesic effects.

106 Propofol: Controversial Rapid smooth induction, rapid awakening.
Dose: 2-2.5mg/kg F:M 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 Vecuronium: Rocuronium: 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) mg/kg (48 sec) Duration of action prolonged: Anticipated difficult airway Vecuronium: Dose:0.1 mg/kg(onset time -144 sec) Used when scholine is contraindicated Dose reduction not needed because the decrease in pseudocholinestrase activity in pregnancy is offset by increase in total body water.


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