1. During pregnancy, there are significant hemodynamic changes including increased blood volume, cardiac output, and regional blood flow to the uterus and placenta. The hematocrit decreases due to disproportionate rises in plasma volume. 2. Respiratory changes include increased tidal volume, minute volume, and oxygen consumption due to effects of progesterone. Low carbon dioxide levels and risk of difficult intubation are seen. 3. Other changes involve increased renal blood flow and glomerular filtration rate, hypercoagulability, and increased permeability of the placenta to lipid soluble drugs like general anesthetics. These changes are important considerations for anesthesia management in pregnancy and the peripartum period.

2. 1. Hemodynamic Changes
1) Blood volume increases from 65–70 to 80–85 mL kg, mainly by expansion of plasma volume.
2) Red cell volume increases linearly but not as much as plasma volume.Thus, the hematocrit
decreases, causing the ‘physiological anemia of pregnancy.
3) Increase in cardiac output within the first 10–12 weeks by approximately 1.5 L min. By the third
trimester, cardiac output has increased by about 40–50% as a result of significant increases in heart
rate and stroke volume. In labour, cardiac output may increase by a further 45% .
4) pulmonary capillary wedge pressure (PCWP) and central venous pressure do not increase, because
of the relaxant effect of progesterone on the smooth muscle of arterioles and veins, and dilatation
of the left ventricle.
PHYSIOLOGICAL CHANGES DURING PREGNANCY

3. CARDIOVASCULAR CHANGES IN PREGNANCY

4. HAEMATOLOGICAL CHANGES ASSOCIATEDWITH
PREGNANCY

5. Aortocaval Compression
Pregnant women who lie supine may suffer from aortocaval compression.Arterial pressure decreases
because the gravid uterus compresses the inferior vena cava to reduce venous return and therefore
cardiac output.
Regional Blood Flow
There is an increased blood flow to various organs, especially the uterus and placenta, where it rises
from 85 to 500 mL min. Liver blood flow is not increased. Blood flow to the nasal mucosa is increased.
Nasal intubation may be associated with epistaxis.

6. The larger airways dilate and airway resistance decreases.There are increases in tidal volume (from 10 to
12 weeks’ gestation) and minute volume (by up to 50%). Progesterone exerts a stimulant action on the
respiratory center and carotid body receptors.Alveolar hyperventilation leads to a low arterial carbon
dioxide tension (PaCO2) during the second and third trimesters. Oxygen consumption (Vo2) increases
gradually from 200 to 250 mL min at term (up to 500 mL min in labour).
2. RESPIRATORY CHANGES:
Changes in Respiratory
Function in Pregnancy

7. The incidence of failed intubation in term parturients is approximately 1 in 300 cases, compared with 1
in 2200 in the non-pregnant population.This is caused in part by changes in pregnancy which affect the
airway.
Physiological Changes of PregnancyWhich Increase the Risk of Hypoxaemia:
1) Interstitial oedema of the upper airway, especially in pre-eclampsia
2) Enlarged tongue and epiglottis
3) Enlarged, heavy breasts which may impede laryngoscope introduction
4) Increased oxygen consumption
5) Restricted diaphragmatic movement, reducing FRC

8. 1. Renal blood flow is increased.
2. By 10–12 weeks, glomerular filtration rate (GFR) has increased by 50% and remains at that level
until delivery.
3. Glycosuria often occurs because of decreased tubular reabsorption and the increased load.
4.Gastrointestinal Changes
These also stem from the effects of progesterone on smooth muscle.
A reduction in lower oesophageal sphincter pressure occurs before the enlarging uterus exerts its
mechanical effects (an increase in intragastric pressure and a decrease in the gastro-oesophageal
angle).These mechanical effects are greater when there is multiple pregnancy, hydramnios or morbid
obesity. Placental gastrin increases gastric acidity.Together with the sphincter pressure
changes, this makes regurgitation and inhalation of acid gastric contents more likely to
cause pneumonitis in pregnancy.
3. RENAL SYSTEM

9. Pregnancy induces a hypercoagulable state.
There is an increase in the majority of clotting factors, a decrease in the quantity of natural
anticoagulants and a reduction in fibrinolytic activity.
The increase in clotting activity is greatest at the time of delivery, with placental expulsion releasing
thromboplastic substances.These substances stimulate clot formation to stop maternal blood loss.
Coagulation and fibrinolysis generally return to pre-pregnant levels 3–4 weeks postpartum.
5. COAGULATION

10. 1) MolecularWeight And Lipid Solubility:The placental membrane is freely permeable to lipid
soluble substances.The majority of anaesthetic drugs are small (molecular weights of less than 500
Da) and lipid-soluble and so cross the placenta readily.The main exceptions are the neuromuscular
blocking drugs.
2) Materno-Fetal Concentration Gradient: Drug transfer occurs down a concentration gradient in
either direction.The maternal drug concentration depends on the route of administration, dose,
volume of distribution,drug clearance and metabolism.
3) Protein Binding:A dynamic equilibrium exists between bound (unavailable) and unbound (available)
drug.
4) Degree Of Ionization:The placental membrane carries an electrical charge; ionized molecules with
the same charge are repelled, while those with the opposite charge are retained within the
membrane.
5) MaternalAnd Fetal PH: Changes in maternal or fetal pH alter the degree of ionization and protein
binding of a drug, and thus its availability for transfer.
FACTORS DETERMINING PLACENTALTRANSFER

11. 1. Inhalational anaesthetics diffuse readily, but provided that the induction-delivery interval is short, the
fetus is minimally affected.
2. Neuromuscular blocking drugs, which are quaternary ammonium compounds and ionized fully, cross
the placenta very slowly. Only prolonged administration of a muscle relaxant, e.g. in the intensive care unit,
might lead to neonatal paralysis. Bolus doses of succinylcholine are safe.
3. Thiopental is highly lipid-soluble, weakly acidic, 75% protein-bound and less than 50% ionized at
physiological pH. It therefore crosses the placenta rapidly. Doses of thiopental greater than 8 mg kg
produce neonatal depression, whereas doses of less than 4 mg kg produce no significant neonatal effects
provided that the induction to delivery time is less than 5 min.Thiopental in such doses does not affect
Apgar score .
4. Propofol is highly protein-bound, neutral and lipophilic. Propofol has been used for both induction and
maintenance of anaesthesia for caesarean section. Induction doses as low as 2–3 mg kg and maintenance
doses as low as (5 mg kg h) have been shown to cause significant neonatal depression. Neonatal
elimination of propofol is slower than that in adults. Unless thiopental is contraindicated, there seems little
advantage in using propofol for caesarean section.
EFFECTS OF DRUGS ON THE NEONATE

12. 5. Diazepam : should be avoided,.The neonate may suffer from respiratory depression, hypotonia,
poor thermoregulation and raised bilirubin concentrations.
6. Opioids are mainly weak bases bound to α1-glycoprotein. Pethidine and its metabolite
norpethidine depress all aspects of neurobehaviour in the neonate. Fentanyl is highly lipid-soluble and
albumin-bound, and rapidly crosses the placenta.Apgar scores are low after administration of
intravenous fentanyl. Epidural administration of fentanyl in doses of less than 200 µg is not associated
with any adverse effect on the fetus , Remifentanil crosses the placenta readily but appears to have few
adverse effects on the fetus/neonate because it is rapidly metabolized. It can be used for patient-
controlled
analgesia (PCA) in labour.
7. Non-steroidal anti-inflammatory drugs : should be avoided in pregnancy because they can
result in premature closure of the ductus arteriosus and premature birth.

13. Syntocinon (Oxytocin)
Syntocinon is a synthetic analogue of the posterior pituitary hormone oxytocin, which is responsible for
effective uterine muscle contraction.It is used during labour to augment progress, at delivery to aid placental
delivery and closure of uterine vasculature and in the postpartum period to reduce postpartum
haemorrhage. For augmentation or induction of labour, Syntocinon is usually administered via a syringe or
volumetric pump using an increasing dose.The usual dose at delivery is 5 international units (IU), and 40 IU
may be infused over 4 h to maintain myometrial contraction and reduce bleeding.
Syntocinon may cause vasodilatation and tachycardia and so should be administered cautiously in the
presence of hypovolemia and in patients with significant cardiac disease. Syntocinon also has an antidiuretic
hormone effect.
Ergometrine
Ergometrine is also given to stimulate uterine contraction,usually in a dose of 500 µg. Ergometrine causes
peripheral vasoconstriction,which may be severe, leading to hypertension and pulmonary oedema; thus it
should be avoided in women with hypertensive disease.
UTEROTONIC DRUGS

14. Syntometrine
Syntometrine is a combination of ergometrine 500 µg and Syntocinon 5 units. Until recently, it was
administered routinely by intramuscular injection at the delivery of the anterior shoulder to assist in
placental separation and to reduce postpartum haemorrhage; however, Syntocinon alone is now
favoured because of its reduced side effect profile.
Prostaglandins
Carboprost
Carboprost is prostaglandin F2α. It has an important role in the treatment of severe uterine atony
unresponsive to Syntocinon or ergometrine. It is administered intramuscularly (250 µg). It should not
be given intravenously or intramyometrially.It may induce bronchospasm and hypertension and should
be avoided in asthmatics
Misoprostol
Misoprostol is a prostaglandin E1 analogue. It may be used to induce labour and is given vaginally. It
may be given as third or fourth line treatment of postpartum haemorrhage (600 µg p.r.). It produces
pyrexia, shivering, nausea and vomiting, and diarrhoea.

15. β2-Adrenergic Receptor Agonists (Terbutaline, Salbutamol, Ritodrine)
These act on uterine β2-receptors causing relaxation of the myometrium.They can be given orally,
subcutaneously or by intravenous infusion for premature labour.The effects should be monitored
carefully because severe tachycardia, hypotension, pulmonary oedema, hypokalaemia, and
hyperglycaemia may occur.
TOCOLYTIC DRUGS

16. Indomethacin is an NSAID and a prostaglandin synthetase inhibitor. It may be given orally or rectally to
inhibit contractions after cervical circlage. It can cause premature closure of the fetal ductus arteriosus
and therefore should not be used after 32 weeks’ gestation.
INDOMETHACIN

17.  Cardiovascular diseases (14%).
 Cardiomyopathy (13%).
 Hemorrhage (12%).
 Non cardiovascular diseases (12%).
 Hypertensive disorders of pregnancy (11%).
 Infection/sepsis (11%).
 Thrombotic pulmonary embolism (6%).
 Amniotic fluid embolism (6%).
 Cerebrovascular accidents (5%)
 Anesthesia-related complications (<1%).
THE LEADING CAUSES OF DEATH ASSOCIATEDWITH
A LIVE BIRTH IN 2010

18. INCIDENCE OF SEVERE OBSTETRIC MORBIDITY

19. The pain of labor arises from
1) contraction of the myometrium against the resistance of the cervix and perineum,
2) progressive dilation of the cervix and lower uterine segment,
3) stretching and compression of pelvic and perineal structures.
Discomfort during the first stage of labor is primarily visceral pain resulting from uterine
contractions and cervical dilation. It is usually initially confined to the T11–T12 dermatomes
during the latent phase, but eventually involves the T10–L1 dermatomes as labor enters the
active phase.The visceral afferent fibers responsible for labor pain travel with sympathetic
nerve fibers first to the uterovaginal plexus, then through the inferior hypogastric plexus,
before entering the spinal cord with the T10–L1 nerve roots.
THE PHYSIOLOGY OF PAIN IN LABOR

20. PAIN PATHWAYS IN LABOUR

21. POTENTIAL EFFECTS OF
MATERNAL
HYPERVENTILATION AND
SUBSEQUENT HYPOCARBIA
ON OXYGEN DELIVERY TO THE
FETUS

22. Severe and prolonged pain is associated with sympathetic autonomic hyperactivity, increased
maternal heart rate and blood pressure, vasoconstriction, increased oxygen consumption and
reduced fetal oxygenation.
Ideal pain relief in labor
SHOULD:
• Provide good analgesia.
• Be safe for mother and baby.
• Be predictable and constant in its effects.
• Be reversible if necessary.
• Be easy to administer.
• Be under the control of the mother.
SHOULD NOT:
• Interfere with uterine contractions.
• Interfere with mobility.
EFFECTS OF LABOR PAINS

23. 1. Non-pharmacological analgesia: Birthing techniques such as hydrotherapy, hypnobirthing, patterned
breathing, relaxation, and visualization can increase the production of endogenous endorphins that bind to
receptors in the brain for pain relief
2. Pharmacological analgesia
3. Regional analgesia
Pharmacological analgesia
• Nitrous oxide (Entonox):
Entonox is premixed NO and O2 as a 50:50 mixture. It is self administered and has quick onset of action and a
short half-life.
Side effects include feeling faint, nausea and vomiting.
• Narcotic agents:
Pethidine is administered at a dose of 50-150mg, onset of action is 15-20mins, lasts for 3-4 hrs, usually given
with an antiemetic. If given within 2 hrs of delivery, can cause neonatal respiratory depression and naloxone
may be needed.
Diamorphine is also used in some units at a dose of 2.5-5mg.There is controversy about the extent and
timing of neonatal respiratory depression, but it may be up to 3-4 hrs after last dose.
TYPES OF LABOR ANALGESIA

24. 1) Epidural block.
2) Spinal block.
3) Combined Spinal Epidural (CSE).
4) Continuous spinal analgesia.
5) Paracervical block.
6) Lumbar sympathetic block.
7) Pudendal block.
REGIONAL ANALGESIA AND ANESTHESIA

25. Indications of EA
Pain experienced by a woman in labor
When medically beneficial to reduce the stress of labor
Advantages of EA
• It provides effective analgesia in labour.
• Reduced maternal secretion of catecholamines, which benefits the fetus.
• Can be used when topped up for an operative delivery and for any complications of the 3rd stage of
labour, e.g. retained placenta or repair of perineal tears.
• Can provide effective postoperative analgesia.
• Can be used as an additional method of controlling blood pressure in pre-eclampsia.
EPIDURAL ANALGESIA

26. • Failure to site, or a patchy or incomplete block.
• Hypotension from sympathetic blockade.
• Decreased mobility.
•Tenderness over the insertion site.
• Inadvertent dural puncture
• Respiratory depression.
• Extremely rare complications resulting in neurological deficits.
DISADVANTAGES AND COMPLICATIONS OF EPIDURAL
ANALGESIA

27. Absolute
• Maternal refusal
• Lack of personnel/facilities
• Pre-existing coagulopathy
• Local infection at insertion site.
• Raised intracranial pressure (risk of coning)
• Drug allergy.
Relative
• Haemodynamic instability.
• Anatomical abnormalities.
• Neurological disorders (medicolegal implications)
• Systemic infection.
CONTRAINDICATIONSTO EPIDURAL ANALGESIA

28. COMPARISON OF SITTING AND LATERAL POSITIONS

29. An alternate to epidural analgesia, in whom EA is contraindicated and who are not able to obtain
adequate analgesia from more conventional methods such as nitrous oxide.
Remifentanil is a powerful opiate, rapidly metabolized and unable to cross the placenta. Its
administration via a patient-controlled IV system has shown promise in providing analgesia.
Advantages:
 Flexibility and benefit of self administration
 Ability to minimize drug dosage
 Reduced demand on professional time
Disadvantages:
 May provide uneven block Addition of a basal infusion provides:
 More even block producing greater patient satisfaction
REMIFENTANIL PCA

30. Advantages of CSE for Labor Analgesia
1. Rapid onset of intense analgesia.
2. Very low failure rate.
3. Less need for supplemental boluses.
4. Minimal motor block (“walking epidural”)
Maintenance of epidural analgesia can be achieved by
I. regular top-ups
II. an epidural infusion
III. patient-controlled epidural analgesia (PCEA).
COMBINED SPINAL EPIDURAL (CSE)

31. Intermittent bolus injections:
• Bupivacaine: 0.125%-0.375%, 5-10 ml, duration:1-2 hr
• Ropivacaine: 0.125%-0.25%, 5-10 ml, duration: 1-2 hr
• Lidocaine: 0.75%-1.5%, 5-10 ml, duration: 1-1.5 Hr
Continuous Infusion of Dilute Local Anesthetic Plus Opioid
• Better pain relief while producing less motor block.
• Maternal and neonatal drug concentrations safe.
Regimen
(0.0625% - 0.08%) bupivacaine with (2-3 mcg /ml)
fentanyl, with or without epinephrine, infusing at
10-12 ml/hour

32. • Results still preliminary but it appears safe for labor analgesia and may offer some advantages
• Some routinely use spinal macro catheters through standard epidural needles for obese parturient or
parturient with kyphoscoliosis.
CONTINUOUS SPINAL ANALGESIA

33. An injection of pain medicine into the tissues around the cervix is called a paracervical block.
A paracervical block is another form of local anesthesia. It reduces the pain caused by contractions
and stretching of the cervix.A paracervical block lasts about 1 to 2 hours.
PARACERVICAL BLOCK IN LABOR

34. To relieve pain associated with the second (pushing) stage of labor, an injection called a pudendal
block can be given through the vaginal wall and into the pudendal nerve in the pelvis, numbing the
area between the vagina and anus (perineum). Pudendal blocks do not relieve the pain of
contractions
PUDENDAL BLOCKS IN LABOR

35. A recommended classification is:
1) Emergency: there is immediate threat to the life of mother or fetus.(massive bleeding (placenta previa
or accreta, abruptio placentae, or uterine rupture), umbilical cord prolapse, and severe fetal distress).
2) Urgent: maternal or fetal compromise that is not immediately life threatening.
3) Scheduled: no maternal or fetal compromise, but needs early delivery.
4) Elective: delivery timed to suit mother and staff.
Cesarean section:
• For all emergency cesarean sections, the patient must be transferred to theatre as rapidly as possible.
• In most centres, general anaesthesia is used when an immediate cesarean section is required.
• Urgent cesarean sections are usually performed under regional anaesthesia.
•There is an expectation that the decision to delivery time should be less than 30min when the indication
for cesarean section is fetal distress.
CESAREAN SECTION

36. UK CESAREAN SECTION
/YEAR

37.  Spinal anaesthesia
 Epidural anaesthesia
 Combined spinal epidural (CSE)
 General anaesthesia
ANAESTHETIC TECHNIQUES FOR CESAREAN SECTION

38. Fasting and antacid precautions are ideal, as GA may be required if the block is unsatisfactory.
Good intravenous access is essential to provide fluids rapidly to counteract hypotension that may
occur.Vasopressor drugs, such as phenylephrine or ephedrine, should also be available.
Hyperbaric bupivacaine 0.5% in a dose of 12.5- 15mg is usually used, together with an opiate such
as fentanyl(20mcg) or diamorphine (around 250mcg).
SPINAL ANAESTHESIA

39. The patient is usually placed in the lateral decubitus or sitting position, and a hyperbaric solution of
intrathecal lidocaine (50 to 60 mg) or bupivacaine (10 to 15 mg) is injected. Bupivacaine should be
chosen if the obstetrician will not likely complete the surgery in 45 minutes or less. Use of a 22-gauge
or smaller, pencil-point spinal needle (Whitacre, Sprotte) decreases the incidence of PDPH.Adding
fentanyl, 10 to 25 mcg, or sufentanil, 5 to 10 mcg, to the intrathecal local anesthetic solution enhances
the intensity of the spinal block and prolongs its duration without adversely affecting neonatal
outcome.Addition of preservative-free morphine, 0.1 to 0.3 mg, can prolong postoperative analgesia
up to 24 h
Because of the associated sympathetic blockade, patients should receive an appropriate intravenous
bolus of crystalloid such as lactated Ringer’s (typically 1000–1500 mL) solution at the time of neural
blockade.
SPINAL ANESTHESIA

40. Advantages:
• Can be topped up to prolong the anaesthesia, should the surgery be extended.
• Can be used for good postoperative analgesia.
Disadvantages:
• Patchy or unilateral blockade.
•Takes longer to establish an adequate block.
• Can be technically difficult to perform with > incidence of headache in the event of inadvertent dural
puncture.
• Fatal complications in case of misplacement.
• Larger doses of anesthesia is required.
EPIDURAL ANAESTHESIA

41. Advantages:
• Smaller volume of local anaesthesia is required.
• Give postoperative analgesia.
Disadvantages:
• Higher risk of failure.
• Higher risk of meningitis.
• Epidural component is untested and any local anaesthetic agent must be given in small boluses.
COMBINED SPINAL EPIDURAL ANAESTHESIA

42. NEUROAXIAL OPIOIDS

43. 1) Post Dural Puncture Headache (PDPH).
2) Neurological complications.
3) Venous puncture e.g. of dural veins
4) Catheter breakage
5) Extensive block (including unplanned blocks)
6) Shivering
7) Backache - Long-term backache is not a complication of neuraxial techniques.
8) Drug side effects
Nausea and vomiting (opiates)
Respiratory depression (opiates)
Anaphylaxis
Toxicity (including intravascular injection of local anaesthetics).
COMPLICATIONS OF REGIONAL ANESTHESIA

44. Indications for GA includes:
I. Maternal request.
II. Urgent surgery.
III. Regional anaesthesia contraindicated ( coagulopathy, maternal hypovolaemia).
IV. Failed regional anaesthesia.
V. Additional surgery planned at the same time as cesarean section.
Problems with GA:
• Potential airway difficulties.
• Pulmonary aspiration of gastric contents.
• Awareness.
GENERAL ANAESTHESIA

45. • History and examination.
• Antacid prophylaxis
• Appropriate monitoring.
• Position supine with left lateral tilt or wedge.
• Preoxygenate for 3-5mins.
• Intubation for adequate ventilation.
• Propofol has also been used for cesarean section without any major reported complications,
although at present thiopental probably is still the most commonly used agent in the UK.
•Ventilate with 50% oxygen in nitrous oxide.
• At the end of procedure give an NSAID e.g. 100mg diclofenac PR.
• Extubate awake in the head-down left lateral position.
• Give additional IV analgesia as required.
TECHNIQUE OF GENERAL ANAESTHESIA

46. Patients requiring anesthetic care for labor or cesarean section should undergo a focused
preanesthetic evaluation as early as possible.
Regardless of the time of last oral intake,all patients are considered to have a full
stomach and to be at risk for pulmonary aspiration.
The minimum fasting period for elective cesarean section should be 6 h for light meals and 8 h for
heavy meals. Prophylactic administration of a clear antacid (15–30 mL of sodium citrate orally) every
30 min prior to a cesarean section may help maintain gastric pH greater than 2.5 and may decrease
the likelihood of severe aspiration pneumonitis.
An H2-blocking drug (eg, ranitidine, 100–150 mg orally or 50 mg intravenously) or metoclopramide 10
mg orally or intravenously, Premedication with oral omeprazole, 40 mg, at night and in the morning,
also appears to be highly effective in high-risk patients undergoing elective cesarean section.
. H 2 blockers reduce both gastric volume and pH but have no effect on the gastric contents already
present. Metoclopramide accelerates gastric emptying, decreases gastric volume, and increases lower
esophageal sphincter tone.Although anticholinergics theoretically may reduce lower esophageal
sphincter tone, premedication with glycopyrrolate, 0.1 mg, helps reduce airway secretions and should
be considered in patients with a potentially difficult airway
ANAESTHESTIC MANAGEMENT

47. Anticipation of a difficult endotracheal intubation may help reduce the incidence
of failed intubation.
check for possible difficult intubation (preoperative tests includes……..)
1) Proper positioning of the head and neck may facilitate endotracheal intubation in
obese patients: elevation of the shoulders, flexion of the cervical spine, and
extension of the atlantooccipital joint
2) A variety of laryngoscope blades, a short laryngoscope handle.
3) Stiletted endotracheal tube (6 mm).
4) Magill forceps (for nasal intubation).
5) Laryngeal mask airway (LMA), an intubating LMA (Fastrach).
6) Fiber optic bronchoscope.
7) video assisted laryngoscope (GlideScope or Stortz CMAC),.
8) The capability for transtracheal jet ventilation.
9) Esophageal–tracheal Combitube should be readily available
DIFFICULT ENDOTRACHEAL INTUBATION

48. Refers to a type of high-frequency ventilation, low tidal volume ventilation provided via a
laryngeal catheter by specialized ventilators that are usually only available in the operating
room or intensive care unit. This procedure is occasionally employed in the operating room
when a difficult airway is anticipated
TRANSTRACHEAL JET VENTILATION

49. Note : A potent volatile agent with oxygen is
employed for general anesthesia, but once the fetus
is delivered, nitrous oxide may be added to reduce
the concentration of the volatile agent; sevoflurane
may be the best volatile agent because it may be
least likely to depress ventilation.
ALGORITHM FOR A
DIFFICULT INTUBATION IN
OBSTETRIC PATIENTS.

50. 1. The patient is placed supine with a wedge under the right hip for left uterine displacement.
2. Denitrogenation is accomplished with 100% oxygen for 3 to 5 min while monitors are applied.
3. The patient is prepared and draped for surgery.
4. When the surgeons are ready, a rapid-sequence induction with cricoid pressure is performed
using propofol, 2 mg/kg, or ketamine, 1 to 2 mg/kg, and succinylcholine, 1.5 mg/kg. Ketamine is used
instead of propofol in hypovolemic patients. Other agents, including methohexital and etomidate, offer
little or no benefit in obstetric patients.
5. With few exceptions, surgery is begun only after proper placement of the endotracheal tube is
confirmed. Excessive hyperventilation (Paco2 <25 mm Hg) should be avoided because it can reduce
uterine blood flow and has been associated with fetal acidosis.
6. Fifty percent air in oxygen with up to 1 MAC expiratory volatile agent is used for maintenance of
anesthesia until delivery of the infant.Thereafter, nitrous oxide up to 70% can be added with a
concomitant reduction of the volatile agent to 0.75% MAC.The low dose of volatile agent helps
ensure amnesia but is generally not enough to cause excessive uterine relaxation or prevent uterine
contraction following oxytocin.
CLINICAL POINTS DURING CESAREAN SECTION

51. 7.A muscle relaxant of intermediate duration (cisatracurium, vecuronium,or rocuronium) is used for
relaxation, but may exhibit prolonged neuromuscular blockade in patients who are receiving
magnesium sulfate
8. For elective caesarean section, a slow 0.3 to 1 IU intravenous bolus of oxytocin over 1 minute,
followed by an intravenous infusion of 5 to 10 IU/h for 4 h, represents an evidence based approach to
dosing for women at low risk of postpartum hemorrhage.
9. If the uterus does not contract readily, an opioid should be given, and the halogenated agent should
be discontinued.Methylergonovine (Methergine), 0.2 mg in 100-mL normal saline as an intravenous
infusion over 10 min

52. Maternal hemorrhage is one of the most common severe morbidities complicating obstetric
anesthesia. Causes include uterine atony, placenta previa, abruptio placentae, and uterine rupture.
 Placenta Previa
A placenta previa is present if the placenta implants in advance of the fetal presenting part; this
occurs in approximately 0.5% of pregnancies.Active bleeding or hemodynamic instability
requires immediate cesarean section under general anesthesia.The patient should have two large-
bore intravenous catheters in place; intravascular volume deficits must be replaced, and blood must
be available for transfusion.The bleeding can continue after delivery because the placental
implantation site in the lower uterine segment often does not contract well as does the rest of the
uterus.
ANTEPARTUM HEMORRHAGE

53.  Abruptio Placentae
Premature separation of a normal placenta, abruptio placentae, complicates approximately 1% to
2% of pregnancies. Most abruptions are mild (grade I), but up to 25% are severe (grade III). Severe
abruptio placentae can cause coagulopathy, particularly following fetal demise. Fibrinogen levels are
mildly reduced (150–250 mg/dL) with moderate abruptions,but are typically less than 150 mg/dL
with fetal demise.The coagulopathy is thought to be due to activation of circulating plasminogen
(fibrinolysis) and the release of tissue thromboplastins that precipitate disseminated intravascular
coagulation (DIC).
Platelet count and factorsV andVIII are low, and fibrin split products are elevated. Severe
abruption is a life-threatening emergency that necessitates an emergency cesarean section.The
need for massive blood transfusion,including replacement of coagulation factors and platelets,
should be considered.

54.  Uterine Rupture
Uterine rupture is relatively uncommon (1:1000– 3000 deliveries) but can occur during labor,
spontaneous rupture following prolonged labor in patients with hypertonic contractions
(particularly with oxytocin infusions).
Uterine rupture can present as frank hemorrhage, fetal distress, loss of uterine tone, hypotension with
occult bleeding into the abdomen, or a combination of these.
Treatment requires volume resuscitation and immediate laparotomy,usually under general anesthesia.
Ligation of the internal iliac (hypogastric) arteries, with or without hysterectomy, may be necessary to
control hemorrhage

55. Hypertension during pregnancy can be classified as:
a) Pregnancy-induced hypertension (preeclampsia).
b) Chronic hypertension that preceded pregnancy.
c) Chronic hypertension with superimposed preeclampsia.
HYPERTENSIVE DISORDERS

56. Preeclampsia :
systolic blood pressure greater than 140 mm Hg or diastolic pressure greater than 90 mm Hg on two
occasions at least 4 h apart after the 20th week of gestation in a woman with previously normal blood
pressure, accompanied by proteinuria (>300 mg/d) and resolving within 48 h after delivery.
When seizures occur, the syndrome is termed eclampsia. HELLP syndrome describes preeclampsia
associated with hemolysis, elevated liver enzymes, and a low platelet count.
Severe preeclampsia causes or contributes to 20% to 40% of maternal deaths and 20% of perinatal
deaths.
Maternal deaths are usually due to stroke, pulmonary edema, hepatic necrosis or rupture, or a
combination of these complications.

57. The pathophysiology of preeclampsia is related to vascular dysfunction of the placenta, resulting in
abnormal prostaglandin metabolism. Patients with preeclampsia have elevated production of
thromboxane A2 (TXA2) and decreased production of prostacyclin (PGI2).TXA2 is a potent
vasoconstrictor and promoter of platelet aggregation, whereas PGI2 is a potent vasodilator and
inhibitor of platelet aggregation. Endothelial dysfunction may reduce production of nitric oxide and
increase production of endothelin.The latter is also a potent vasoconstrictor and activator of platelets.
Marked vascular reactivity and endothelial injury reduce placental perfusion and can lead to
widespread systemic manifestations.
PATHOPHYSIOLOGY & MANIFESTATIONS

58. Severe preeclampsia substantially increases both maternal and fetal morbidity and mortality. Features
of severe preeclampsia include the standard features of preeclampsia in association with any of the
following: blood pressure greater than 160/110 mmHg, thrombocytopenia (<100,000/μL), proteinuria
greater than 5 g/d, impaired liver function, progressive kidney insufficiency (serum creatinine
concentration greater than 1.1 mg/d oliguria, pulmonary edema, and CNS signs or symptoms
(headache or visual disturbances .
Hepatic rupture may occur in patients with the HELLP syndrome.
Patients with severe preeclampsia or eclampsia have widely differing hemodynamic profiles. Most
patients have low-normal cardiac filling pressures with increased systemic vascular resistance, but
cardiac output may be reduced, normal, or increased.

59. Treatment of preeclampsia consists of bed rest, sedation, repeated doses of antihypertensive drugs.
(usually labetalol, 5–10 mg, or hydralazine, 5 mg intravenously), and magnesium sulfate (4 g loading
followed by 1–3 g/h intravenously) to treat hyperreflexia and prevent convulsions.Therapeutic magnesium levels
are 4 to 6 mEq/L. It is recommended that corticosteroids be given if the fetus is viable and 33 weeks of gestation
or less. Invasive arterial and central venous monitoring are indicated in patients with severe hypertension,
pulmonary edema, refractory oliguria, or a combination of these; in such patients an intravenous vasodilator
infusion may be necessary. Definitive treatment of preeclampsia is delivery of the fetus and placenta
TREATMENT

60. Standard anesthetic practices may be used for patients with mild preeclampsia. Spinal and epidural
anesthesia are associated with similar decreases in arterial blood pressure in these patients. Patients
with severe disease, however, are critically ill and require stabilization prior to administration of any
anesthetic, including control of hypertension and correction of hypovolemia. In the absence of
coagulopathy, continuous epidural anesthesia is the first choice for most patients with preeclampsia during labor
and vaginal delivery. Moreover, continuous epidural anesthesia avoids the increased risk of a failed
intubation due to severe edema of the upper airway.
A platelet count and coagulation profile should be checked prior to the institution of regional
anesthesia in patients with severe preeclampsia. It has been recommended that regional anesthesia be
avoided if the platelet count is less than 100,000/μL, but a platelet count as low as 50,000/μL may be
acceptable in selected cases, particularly when the count has been stable and global coagulation, as
measured by thrombelastography testing, is normal. Use of an epinephrine-containing test dose for
epidural anesthesia is controversial because of questionable reliability and the risk of exacerbating
hypertension.
ANESTHETIC MANAGEMENT

61. Intraarterial blood pressure monitoring is indicated in patients with severe hypertension during
both general and regional anesthesia. Intravenous vasodilator infusions may be necessary to control
blood pressure during general anesthesia. Intravenous labetalol (5–10-mg increments) can also be
effective in controlling the hypertensive response to intubation and does not appear to alter placental
blood flow.Te short-term administration of intravenous nicardipine or clevidipine may be used
to treat intraoperative hypertension. Because magnesium potentiates muscle relaxants, doses of
nondepolarizing muscle relaxants should be reduced in patients receiving magnesium therapy and
should be guided by a peripheral nerve stimulator.

62. patients can be divided into one of two groups.
 Patients in the first group benefit from the reduced systemic vascular resistance caused by
neuraxial analgesia and anesthesia techniques, but usually not from excessive fluid administration.
These patients include those with mitral or aortic insufficiency, chronic heart failure, or congenital
lesions with left-to-right shunting.The induced sympathectomy from spinal or epidural techniques
reduces both preload and afterload, relieves pulmonary congestion, and in some cases, increases
cardiac output.
 Patients in the second group do not benefit from a decrease in systemic vascular resistance.These
patients include those with aortic stenosis, congenital lesions with right-to-left or bidirectional
shunting,or primary pulmonary hypertension. Reductions in venous return (preload) or afterload
are usually poorly tolerated.These patients are better managed with intraspinal opioids alone,
systemic medications, pudendal nerve blocks, and, if necessary, general anesthesia
HEART DISEASE

63. Amniotic fluid embolism is a rare (1:20,000 deliveries) but often lethal complication (86% mortality rate
in some series) that can occur during labor, delivery, or cesarean section, or postpartum. Mortality may
exceed 50% in the first hour. Entry of amniotic fluid into the maternal circulation can occur through any
break in the uteroplacental membranes.
Clinical features :
Patients typically present with sudden tachypnea, cyanosis, shock, and generalized bleeding.
Tree major pathophysiological manifestations are responsible:
(1) acute pulmonary embolism,(2) DIC, and (3) uterine atony. Mental status changes, including seizures,
and pulmonary edema may develop; the latter has both cardiogenic and noncardiogenic components.Acute left
ventricular dysfunction is common. (amniotic fluid embolism should always be suggested by sudden respiratory
distress and circulatory collapse.The presentation may initially mimic acute pulmonary thromboembolism, venous
air embolism)
Treatment:
Treatment consists of cardiopulmonary resuscitation and supportive care. Once the patient is resuscitated,
mechanical ventilation, fluid resuscitation, and inotropes are
best provided under the guidance of invasive hemodynamic monitoring. Uterine atony is treated with
oxytocin, methylergonovine, and prostaglandin F2α
AMNIOTIC FLUID EMBOLISM

64. • Most anaesthetic agents, except muscle relaxants, rapidly cross the placenta.
•Thiopental can be detected in the fetus within 30sec of administration.
• Umbilical artery to umbilical vein concentration approach unity at 8mins.
• Opioids administered before delivery may cause fetal depression.
• If there is specific indication for opioid before delivery, they should be given and the paediatrician
informed.
• Hypotension, hypoxia, hypocapnia and excessive maternal catecholamine secretion may all be harmful
to the fetus.
EFFECT OF GENERAL ANAESTHESIA ONTHE FETUS

65. Central nervous system (CNS) depression in the neonate may be manifested by a prolonged time to
sustained respirations,respiratory acidosis, or an abnormal neurobehavioral examination.Moreover,
loss of beat-to-beat variability in the fetal heart rate (seen with most CNS depressants) and decreased
fetal movements (due to sedation of the fetus) complicate the evaluation of fetal well-being during
labor. Long-term fetal heart rate variability is affected more than short-term variability.
FETAL DEPRESSION FOLLOWING GA