Wednesday 29 February 2012

Featal macrosomia: definition,risk factors, diagnosis, complications and management.

Definition of macrosomia:
Generally to describe a very large fetus or a neonate the term macrosomia is used. According to obstetrical practice weight more than  4 kgs is taken as large baby.
Birth weight exceeding the 90 th percentile of the average body weight of the particular gestational age can be taken as macrosomia.
Birth weight two standard deviations above the mean birth weight of that gestational age, means 97 th percentile of mean birth weight is taken as macrosomia.
If birth weight threshold is taken as 4 kgs, exceeding that weight can be taken as macrosomia.
Different countries use their own criteria to define macrosomia. According to American college of obstetricians and gynecologists it is 4500 gms or more.

Risk factors for macrosomia:
Not all mothers who have delivered macrosomic babies will show risk factors. Only 40% of women with macrosomic fetuses will show some risk factors like:
Maternal diabetes mellitus:
As the baby weight goes above 4 kgs the chances of maternal diabetes is more. But this condition is associated only with a small percentage of macrosomic infants.
The processes how maternal diabetes leads to fetal macrosomia:
 
  1.   Maternal hyperglycemia
                                                                     \
                Hypertrophy and hyperplasia of the fetal islet cells of langerhans
                                                                    /
                             Increased secretion of fetal insulin
                                                                    \
                  Stimulates carbohydrate utilization and accumulation of fat
                                                                    /
     Fetal macrosomia

2. insulin like growth factors I and II are also involved in fetal growth and adiposity.
3.in diabetes maternal free fatty acids(FFA) will be  elevated and these will be excessively transformed to fetus leading to acceleration of triglyceride synthesis and which further lead to adiposity.
In macrosomic fetuses of diabetic mother, shoulder circumference will be more and shoulder circumference to head circumference is also more leading to shoulder dystocia and increased proportion of body fat is also associated with labor dystocia and operative delivery.
With good diabetic control the incidence of macrosomia can be reduced.

Familial:
If patients are of large size, the chances of having large baby is more. This is more true when mother is obese, if her weight is above 300 pounds, the fetal macrosomia can be seen in 30% of cases.

Multiparity:
As the birth order goes on increasing the chances of having big babies are more.
Probably because multipara with increasing age more prone to have obesity, diabetes mellitus. The abdomen becomes lax and the space availability will be more for the baby and compared with first pregnancy she will remain tension free as she already experienced the process of pregnancy previously and there will be less incidence of  hyperemesis gravidarum allowing her to take good diet.

Prolonged pregnancy:
In some cases of prolonged pregnancy the baby growth goes on increasing leading to fetal macrosomia.

In elderly mothers:
Chances of  having medical complications like gestational diabetes are more which may lead to macrosomia.
Tendency to prolongation of pregnancy may also lead to macrosomic babies in case of continued growth.

Male fetus:  
The chances of macrosomia is more common in male fetuses may be because of excessive bone mass.

Previous macrosomic baby:
If mother had a baby more than 4 kgs in previous pregnancy she may the have macrosomic baby in present pregnancy also. May be because the same factors which are influenced in the previous pregnancy repeat in present pregnancy.

Depending on race and ethnicity:
in some parts of the world depending on the average size of the people in that particular country incidence of macrosomic babies will alter.
As in USA the cutoff for macrosomic baby is 4.5 kg, in India the average birth weight is 2.5 to 3.5 kg and more than 4 kg is taken as macrosomia.

Weight gain of the mother:
Weight gain of the mother in the present pregnancy will influence the weigh of the baby. Depending on mother’s pre pregnancy weight the weight gain in pregnancy is advised which should be gradual gain. In case of obese women this should be restricted to 6 to 7 kgs and it can be up to 11 to 12 kgs in non obese women.

Diagnosis of macrosomia:
Exact confirmation of macrosomia can be done only after delivery of the baby.
Though accurately cannot be detected some of the estimations can be done to diagnose the fetal weight before delivery like:
·         Disproportionate increase in uterine size.
·         Fetus feels big and firm with hard skull bones.
·         Fetal weight: symphysio fundal height in cms  - 11 × 155 (in case of engaged head)
              symphysio fundal height in cms - 12 × 155 (in case of unengaged head)
·         If abdominal circumference is more than 100 cms it can be taken as big baby.
·         According to ultrasonography measurements, BPD, AC, HC, and FL birth weight can be calculated.
·         Based on BPD and  AC, baby  with BPD of approximately 9.9 cm with AC of 36 cm can be taken as having weight above 4 kgs.
·         Based on FL and AC, baby with FL of around 8 cm and AC of around 36 cm can be taken as above 4 kg baby.
·         Head to abdomen ratio < 0.9 indicates head to body disproportion with increased risk of shoulder dystocia.
·         Ultrasonography will give fetal weight about ± 15% of actual birth weight.
·         But the obesity of the mother and skill of the sonologist will decide the accuracy of the measurements.

Risks that can occur due to macrosomia:
·         Cephalo pelvic disproportion can occur during labor.
·         Shoulder dystocia can arise especially in diabetic patients.
·         These can lead to prolonged labor or obstructed labor leading to increased chances of operative interference.

·          Maternal  morbidity increases due to:
Chances  of prolonged labor leading to infections, operative deliveries, injuries to the genital tract.
 In  neglected cases even uterine rupture may occur leading to maternal mortality. Postpartum hemorrhage can occur due to either atonicity because of excessive distension of uterus or traumatic due to operative interference.

·         Fetal complications likely to occur are:
Injuries  to babies due to operative interference.
Shoulder dystocia can lead to brachial plexus injury.
Fetal asphyxia and further consequences can occur due to prolonged or obstructed labor.
Meconium aspiration syndrome can occur due to above causes.
Macrosomic babies of diabetic mothers may have hypoglycemia after birth.
If the baby remains obese in future other obesity related disorders can occur.

Management of pregnancy with macrosomic baby:
Induction of labor:
Labor can be induced prophylactically when macrosomia is diagnosed to prevent further growth of the baby. But this is not found to prevent the chances of caesarean delivery or shoulder dystocia.

Elective caesarean delivery:
Caesarean delivery can be planned electively in women having macrosomic baby to prevent delivery complications.
But the risks of caesarean delivery to be kept in mind. Economically also it will create burden to the patient’s family.
But it is acceptable in macrosomic babies of diabetic mothers with fetal weight of > 4.25 to 4.5 kg as the chances of shoulder dystocia is more in these cases.

Prevention of shoulder dystocia:
When the fetal head passes through maternal pelvis but shoulders cannot pass because of very large diameter leading to impaction of anterior shoulder against maternal symphysis pubis that condition is called shoulder dystocia.
In dealing with macrosomic baby the chances of shoulder dystocia to be kept in mind, if it occurs the measures to be taken are:
First  liberal medio lateral episiotomy to be given.
Mc Robert’s manoeuvre: maternal thighs to be abducted and sharply flexed on to her abdomen this process may relieve the impacted anterior shoulder.
 If not then head and neck should be grasped and taken posteriorly and simultaneous supra pubic pressure to be applied by assistant slightly towards fetal chest, by doing this fetal bisacromial diameter can be reduced and anterior shoulder can be rotated obliquely.
Wood’s manoeuvre: if above method also fails general anesthesia to be given, the posterior shoulder to be rotated to anterior position keeping it inside the pelvis by a screwing movement with simultaneous suprapubic pressure in opposite direction.
Zavanelli’s manoeuvre: fetal head to be flexed and replaced within the uterus and baby will be delivered by emergency caesarean section.
In case of dead fetus or live anencephalic fetus which is not able to deliver cleidotomy can be done, that is cutting one or both clavicles to reduce the shoulder girth.
Because of shoulder dystocia brachial plexus injury, birth asphyxia or even fetal death can occur.

Monday 27 February 2012

Role of general anesthesia in obstetric practice: preparation, induction, intubation, gaseous agents used and complications.

Nowadays the usage of general anesthesia is decreasing as  regional analgesia is becoming popular. General anesthesia  is having relatively higher risk. Though incidence of case fatality is low, it  is more with general anesthesia for cesarean delivery than regional anesthesia.

Compared with the non pregnant population a 10-fold higher rate of failed intubation noted in pregnant women and it occurs in approximately 1 of every 250 general anesthetics administered.
According to these findings it can be concluded that concluded that regional analgesia is the preferred method of pain control in pregnant and should be used unless contraindicated.
Compared with regional analgesia trained personnel and specialized equipment
 including fiberoptic intubation are mandatory for the safe use of general anesthesia.

Preparation of the  patient for general anesthesia:
To minimize the risk of complications for the mother and fetus several steps should be taken prior to anesthesia induction, like  the use of antacids, lateral uterine displacement, and preoxygenation.

Giving antacids:
Giving antacids before induction is more important in general anesthesia than any other method to decrease mortality from chance of aspiration of gastric contents.
Normally preferred is 30 mL of sodium citrate with citric acid  called Bicitra, given about 45 minutes before surgery, neutralizes gastric contents in nearly 90 percent of women undergoing cesarean delivery. It can also be given within a few minutes of the anticipated time of anesthesia induction, either by general or major regional block.
If more than 1 hour has passed between when the first dose was given and when anesthesia is induced, then a second dose to be given.
Intravenous administration of ramiprazole or pantaprazole or omeprazole can also be used.

Uterine Displacement:
 Generally the  uterus may compress the inferior vena cava and aorta when the mother is in the supine position. With lateral uterine displacement, the duration of general anesthesia has less effect on neonatal condition than when the woman remains supine.

Preoxygenation:
As gravid uterus pushes the diaphragm above the functional reserve capacity of the lungs is reduced in pregnant women . So, they  become hypoxemic more rapidly during periods of apnea than do non pregnant patients.
It  is important first to replace nitrogen in the lungs with oxygen  to minimize hypoxia between the time of muscle relaxant injection and intubation. It  is done by administering 100 percent oxygen via face mask for 2 to 3 minutes prior to anesthesia induction. In case of emergency, similar benefit can be obtained by  four vital capacity breaths of 100-percent oxygen via a tight breathing circuit.

Induction of general anesthesia:

Thiopental:
 Thiopental belongs to thiobarbiturate group which is given intravenously is widely used and having  the advantages of ease and extreme rapidity of induction as well as prompt recovery with minimal risk of vomiting.
But thiopental and similar compounds are poor analgesic agents. So, large amount of drug is needed  to maintain anesthesia by it alone. And it may cause appreciable newborn
depression. Because of this thiopental is not used as the sole anesthetic agent and  is administered in a dose that induces sleep.

Ketamine:
 This agent may also be used to make the patient unconscious. Ketamine may be used to produce analgesia and sedation just prior to vaginal delivery  intravenously in low doses of 0.2 to 0.3 mg/kg. Whereas in doses of 1 mg/kg used to induce general anesthesia.

 Unlike thiopental ketamine is not associated with hypotension. So, it is useful in women with acute hemorrhage. But  it usually causes a rise in blood pressure, and thus to be avoided in women who are already hypertensive. Unpleasant delirium and hallucinations are commonly induced by this agent.

Intubation:
Immediately after the patient becomes unconscious, a muscle relaxant to be given to facilitate intubation.
The commonly used agent is succinylcholine, which is havind  a rapid-onset and short duration of action.
 To occlude the esophagus from induction until intubation is completed, cricoid pressure is used in sellick maneuver. Before the operation begins, proper placement of the endotracheal tube must be confirmed by  auscultating the bilateral breath sounds and by end-tidal carbon dioxide analysis.

Failed or difficult intubation:
Though rare,  failed intubation is a major cause of anesthesia-related maternal mortality.
Among the maternal deaths associated with general anesthesia,  22 percent of deaths can be attributed to induction or intubation problems.
Difficult intubation can be predicted to some extent by verifying the history of previous difficulties with intubation and by careful assessment of anatomical features of the neck, maxillofacial, pharyngeal, and laryngeal structures.Sometimes intrapartum edema may develop though initial assessment of the airway was uneventful, and can create problems in intubation. Morbid obesity is also a major risk factor for failed or difficult intubation.
To prevent or to face these problems appropriate preoperative preparation with immediate
availability of specialized equipment, including a variety of different shaped laryngoscopes, laryngeal mask airways, a fiberoptic bronchoscope, a transtracheal ventilation set, as well as liberal use of awake oral intubation techniques are important.

Management of failed intubation:
 The operative procedure should be started only after it has been ascertained that tracheal
intubation has been successful and that adequate ventilation can be accomplished. This should be followed  even in case of an abnormal fetal heart rate pattern.
In case of failed intubation:
The  woman must be allowed to awaken and a different technique used, such as an awake intubation or regional analgesia.
Or  the woman is ventilated by mask and cricoid pressure is applied to reduce the chance of aspiration and the surgery may proceed with mask ventilation or the woman may be allowed to awaken.

In some cases where the woman has been paralyzed, and  ventilation cannot be reestablished by insertion of an oral airway, laryngeal mask airway, or use of a fiberoptic laryngoscope to intubate the trachea, then a life-threatening emergency exists. In this case to restore ventilation, percutaneous or even open cricothyrotomy is performed, and jet ventilation to be given.

Gas anesthetics used in general anesthesia:
After  securing the endotracheal tube, a 50:50 mixture of nitrous oxide and oxygen is
administered to provide analgesia. To  provide amnesia and additional analgesia  a volatile halogenated agent can be added.

Volatile anesthetics:
Isoflurane  is the most commonly used volatile anesthetic. Isoflurane  and halothane both are potent, nonexplosive agents and produce remarkable uterine relaxation when given in high, inhaled concentrations. High concentrations are restricted to uncommon situations where uterine relaxation is a requisite rather than a hazard, like for internal podalic version of the second twin , breech decomposition and replacement of the acutely inverted uterus. As soon as the manoeuvre has been completed, anesthetic administration should be stopped and immediate efforts begun to promote myometrial contraction to
minimize hemorrhage.

Side effects:
 Halothane and isoflurane may intensify the adverse effects of maternal hypovolemia by their cardiodepressant and hypotensive effects.
Occasionally  these  agents have been associated with hepatitis and massive hepatic necrosis.

Complications of general anesthesia:

Anesthesia gas exposure and pregnancy outcome:
 All  anesthetic agents that depress the maternal central nervous system will cross the placenta and depress the fetal central nervous system. So, the newborn immediately following delivery with a general anesthetic should get respiratory support. Induction to delivery time should be minimized when general anesthesia is used.
 Fetal exposure of more than 8 minutes is shown to be associated with increased neonatal depression.
But some studies showed no significant differences in short-term measures of neonatal outcome, including Apgar scores, umbilical artery blood gas determinations, or length of stay in between general or regional anesthesia.

Extubation:
The extubation can become a problem sometimes as patient may not recover from general anesthesia in case of poor general condition or because of prolonged anesthesia period.
When  the woman is conscious to a degree that enables her to follow commands and is capable of maintaining oxygen saturation with spontaneous respiration then the tracheal tube can be safely removed.
 The  stomach should be emptied via a nasogastric tube prior to extubation.

Aspiration :
As  Mendelson, who is an obstetrician first described massive gastric acidic inhalation causing pulmonary insufficiency from aspiration pneumonitis, the syndrome bears his name.  
It was the most common cause of anesthetic deaths in the past in obstetrics. In a survey of
maternal deaths between 1979 and 1990, inhalation of gastric contents was associated with 23 percent  anesthesia related deaths.
Important  procedures in  effective prophylaxis are use of antacids, skilful intubation accompanied by cricoid pressure, emptying of the stomach with a nasogastric tube and use of regional analgesia whenever possible.

Fasting time required to prevent aspiration:
In  uncomplicated laboring women clear liquids such as water, clear tea, black coffee, carbonated beverages and fruit juices without pulp may be allowed but obvious solid foods should be avoided.
A fasting period of 8 hours or more is preferable for uncomplicated parturients undergoing elective cesarean delivery. Even after taking these precautions, it should be assumed that any woman in labor is having both gastric particulate matter as well as acidic contents.


Pathophysiology of aspiration pneumonitis:
 If  the pH of aspirated fluid was below 2.5 chances of developing severe chemical pneumonitis are more.
The  right lower lobe is most often involved as the right main stem bronchus usually offers the simplest pathway for aspirated material to reach the lung parenchyma. In severe
cases, there may be bilateral widespread involvement.
Depending  on the material aspirated and the severity of the process the woman may develop evidence of respiratory distress immediately or as long as several hours after
aspiration,. Aspiration of a large amount of solid material causes obvious signs of airway obstruction. Smaller particles without acidic liquid may lead to patchy atelectasis and
later to bronchopneumonia.
In case of  inspiration of highly acidic liquid , decreased oxygen saturation along with tachypnea, bronchospasm, rhonchi, rales, atelectasis, cyanosis, tachycardia, and hypotension are likely to develop. At the sites of injury, pulmonary capillary leakage
results in protein-rich fluid containing numerous erythrocytes exuding from capillaries into the lung interstitium and alveoli to cause decreased pulmonary compliance, shunting of blood, and severe hypoxemia.
In X ray, radiographic changes may not appear immediately and they may be quite variable, although the right lobe most often is affected. Therefore, chest radiographs alone can not exclude aspiration.

Treatment of aspiration pnemonitis:
 In case of having suspicion of aspiration of gastric contents  very close monitoring is needed to note the evidence of any pulmonary damage. By  pulse oximetry, respiratory rate and oxygen saturation are measured. These  are the most sensitive and earliest indicators of injury.
If chance of aspiration is predicted, immediately as much of the inhaled fluid as possible should be wiped out of the mouth and removed from the pharynx and trachea by suction. Saline lavage is not recommended as it may further disseminate the acid throughout the lung. Bronchoscopy may be indicated to relieve airway obstruction if large particulate matter is inspired.
There is no convincing clinical or experimental evidence that corticosteroid therapy or prophylactic antimicrobial administration is beneficial .
But clinical evidence of infection develops, however vigorous treatment with above agents to be given. In case of development of acute respiratory distress syndrome, mechanical ventilation with positive end-expiratory pressure to  given to save the life.

Saturday 25 February 2012

Role of epidural analgesia in obstetric practice: technique, uses,complications and contraindications, combined analgesia and local infiltration

Epidural analgesia is a form of regional analgesia, which  can be used for relief from the pain of labor and childbirth and also used in cesarean delivery. In this procedure a local anesthetic agent is injected  into the epidural or peridural space.
 The epidural space contains areolar tissue, fat, lymphatics and the internal venous plexus. The vessels of internal venous plexus become engorged during pregnancy because of this  the volume of the epidural space becomes appreciably reduced.
To give obstetrical analgesia  usually  needle is passed through a lumbar inter vertebral space, whereas to give caudal epidural analgesia needle is passed through the sacral hiatus and sacral canal.
The advantage of epidural analgesia is, although normally one injection may be used, but if necessary  the injections can be repeated by putting an indwelling catheter or can be given by continuous infusion using a volumetric pump.

Continuous lumbar epidural block:
In case of vaginal delivery to achieve complete analgesia from the pain of labor  a block from
the T10 to the S5 dermatomes is needed.  And in cesarean delivery, a block extending from the T4 to the S1 dermatomes is desired.
The spread of the anesthetic depends upon the location of the catheter tip, the dose, concentration and volume of anesthetic agent used.

The anesthetic agents normally used are:
 2-Chloroprocaine: 
 And  2 to 3% concentrated 300 to 750 mg dose in 15 to 25 ml solution used in epidural block for caesarean delivery with average duration of action for 30 to 60 min.

 Lidocaine:
2 % concentrated 300 to 450 mg dose in 15 to 30 ml solution used in epidural block for caesarean delivery with average duration of action for 60 to 90 min.

 Bupivacaine:
0.5 % concentrated 50 to 100 mg dose in 15 to 20 ml solution can be used in epidural block for caesarean delivery with average duration of action for 90 to 150 min. 
0.25 % concentrated 50 to 100 mg dose in 8 to 10 ml solution used in epidural block for vaginal delivery with average duration of action for 60 to 90 min.

 Ropivacaine:
0.5 % concentrated 75 to 100 mg dose in 15 to 20 ml solution can be used in epidural block for caesarean delivery with average duration of action for 90 to 150 min. 
0.25 % concentrated 20 to 25 mg dose in 8 to 10 ml solution used in epidural block for vaginal delivery with average duration of action for 60 to 90 min.


 The spread of the anesthetic also depends on the position of the woman, whether she  is head-down, horizontal or head-up. The individual variations in the epidural space anatomy also will affect the block, and in some cases, synechiae may preclude a completely satisfactory block.
One more thing to be cautious is  that the catheter tip might move from its original location during the course of labor as the woman moves because of pain.


Technique of giving epidural analgesia:

·         Before giving anesthesia informed and written consent to be taken from th patient and it to be informed to obstetrician.
·         Vitals of the woman to be monitored and continuous fetal heart rate monitoring to be done.
·         Preanesthetic hydration to be given to prevent hypotension with around 1 lit of crystalloids.
·         By putting the woman either in lateral decubitus or in sitting position, epidural needle to be introduced into epidural space depends which type of delivery is planned.
·         The epidural space is identified by loss of resistance and the epidural catheter to be threaded 3 to 5 cm into the epidural space.
·         To identify the tachycardia which may result from accidental intravenous injection of the drug, test dose of 3 ml of 1.5% lidocaine with 1:200,000 epinephrine or 3 ml of 0.25%  bupivacaine with 1:200,000 epinephrine is injected after careful aspiration and after uterine contraction. Signs  of spinal blockade can also be identified by test dose.
·         If no reaction noted then one or two 5 ml doses of 0.25% of bupivacaine can e injected to get cephalad sensory level up to T10.
·         After 15 to 20 min the block to be assessed by loss of sensation to prick or cold. If no block occurred or block is inadequate catheter to be replaced. In case of asymmetrical block the catheter to be withdrawn to 0.5 to 1 cm and additional 3 to 5 ml of 0.25% bupivacaine  to be injected.
·         Analgesia is maintained by intermittent boluses of similar volume, or small volumes of the drug are delivered continuously by infusion pump.
·         The addition of small doses of a short-acting narcotic, either fentanyl or sufentanil, has been shown to improve analgesic efficacy for labor or cesarean delivery.
·         The woman can be placed in lateral or in semi lateral position to avoid aortocaval compression.
·         Vitals of the patient, fetal heart rate and level of analgesia and intensity of motor block to be monitored periodically.
·         To tackle any complications that may arise appropriate resuscitation equipment and drugs must be available during administration of epidural analgesia.


Complications of epidural analgesia:
Though epidural analgesia provides good relief  for most of the women from the pain of labor and delivery ,  some complications can occur. So, close monitoring including the level of analgesia to be performed by trained personnel.
The complication which can arise are:

Total spinal blockade:
Total spinal block can be caused by  dural puncture with inadvertent subarachnoid injection.
In complete spinal block, hypotension and apnea promptly develop and must be immediately treated to prevent cardiac arrest.
 Treatment:
 In the undelivered woman by positioning her laterally, there by  uterus  immediately displaces to lateral side and  aortocaval compression decreases.
 Effective ventilation to be established preferably by tracheal intubation.
 And to correct hypotension intravenous fluids and ephedrine are to be given.
Personnel and facilities must be immediately available to manage this complication.

Ineffective analgesia:
 For the establishment of effective pain relief with maximum safety some time takes. With  continuous epidural infusion regimens such as 0.125-percent bupivacaine with 2-µg/mL fentanyl, 90 percent of women rate their pain relief as good to excellent, and 95 percent express a desire for the same type of analgesia during a future delivery.
But in some studies  few women complained that epidural analgesia is inadequate and they experienced  three or more episodes of pain or pressure.
Risk factors for such breakthrough pain included nulliparity, heavier fetal weights,
and epidural catheter placement at an earlier cervical dilatation. If the epidural analgesia is allowed to dissipate before another injection of anesthetic drug, subsequent pain relief may be delayed, incomplete, or both.
Because of some of these factors some women initially given epidural analgesia may require a general anesthetic for caesarean delivery.
 With  the lumbar epidural technique sometimes, perineal analgesia for delivery is difficult to obtain, at that time a low spinal or pudendal block or systemic analgesia can be added.

Hypotension :
Epidurally  injected analgesic agents may cause hypotension and decreased
cardiac output by blocking sympathetic tracts.
In normal pregnant women, hypotension induced by epidural analgesia usually can be prevented by rapid infusion of 500 to 1000 mL of crystalloid solution, or treated successfully as described for spinal analgesia.
Maintaining  a lateral position minimizes hypotension compared with the supine position by preventing aortocaval compression.
Despite these precautions, hypotension is the most common side effect and is severe enough to require treatment in one third of women.

Central  nervous stimulation:
 Convulsions are an uncommon but serious complication.Immediate steps to be taken are controlling the convulsions, establishing the airway and delivering the oxygen.
To abolish the peripheral manifestations of the convulsions and to allow tracheal intubation succinylcholine is used. To  inhibit convulsions centrally  thiopental or diazepam can be used. Magnesium sulphate may be used in dosage used for  eclampsia to control convulsions.

Maternal pyrexia:
It is found that the  mean temperature in laboring women given epidural analgesia was significantly higher than in those given meperidine.  Some studies have confirmed an increase in intrapartum fever.
Some other important risk factors for maternal pyrexia are  length of labor, duration of ruptured membranes and number of vaginal examinations.
 The  frequency of intrapartum fever was found to be 10 to 15 but the precise etiology of maternal hyperthermia with epidural use is unclear.
The occurrence of maternal pyrexia can be explained by two thoughts that either fever
results from maternal-fetal infection or is caused by dysregulation of body temperature. In these two infection was identified as a reasonable explanation after  studying placental histopathology in these women.
In some studies after labor with epidural analgesia, it was noted that intrapartum fever occurred only with placental inflammation. This suggests that fever is due to infection rather than to the analgesia itself. But other studies contradicted that  proposed mechanism is  alteration in the hypothalamic thermoregulatory set point, impairment of peripheral thermoreceptor input to the central nervous system with selective blockage of warm stimuli or imbalance between heat production and heat loss.
Currently  incomplete information is available regarding the underlying cause.

Back pain:
 Although an association between epidural analgesia and back pain has been reported by some clinicians, others have not found such a relationship.
Some studies are showing that postpartum back pain was common after epidural analgesia, but persistent or chronic back pain was uncommon. Whereas some other studies do not support an association between the use of epidural analgesia and development of new, long-term backache.

Effect of epidural analgesia on Labor:
According to many studies, it is shown that epidural analgesia prolongs labor and increases the need for oxytocin stimulation.
 Epidural  analgesia also shown to prolonge the active phase of labor by 1 hour and also found to increase the need for instrumental delivery due to prolonged second-stage labor. But no adverse neonatal effects are noted.

Effect of epidural analgesia on fetal  heart rate:
 With epidural analgesia no deleterious effects were identified.
Epidural analgesia was associated with improved neonatal acid-base status compared with that with meperidine.

Epidural analgesia leading to cesarean delivery:
 According to several studies it is shown that labor epidural analgesia is associated with increased cesarean deliveries. But  available evidence is insufficient to establish such an association.
Many  investigators belief that the epidural administration of dilute solutions of local anesthetic is less likely to increase cesarean delivery rates than concentrated solutions.
described the effects of introduction of an on-demand labor epidural analgesia service at
The only significant difference that was prominently shown is  increased duration of second-stage labor by approximately 25 minutes.
According to above findings it can be concluded that all women should have access to effective pain relief during labor and the fear of increasing the risk of cesarean delivery should not preclude women from choosing epidural analgesia during labor.

Timing of epidural placement: an association between early epidural placement and a higher rate of cesarean delivery was noted in some studies. Whereas others have shown no difference in early versus late epidural placement in the rates of cesarean  birth, forceps delivery or fetal malposition.
At present there is  insufficient evidence to justify that waiting until a certain degree of
cervical dilatation or fetal station is reached before instituting epidural analgesia is needed or not.

Safety of epidural analgesia:
 The relative safety of epidural analgesia is attested  by many people with a very low incidence of complications and maternal deaths in their experience.

Other complications are pruritis, failed regional block needing general anesthesia, formation of epidural abscess or hematoma etc.


Contraindications of epidural analgesia:
The absolute contraindications to epidural analgesia are:

Refractory maternal hypotension:
Contraindication  to epidural analgesia include actual or anticipated serious maternal hemorrhage, leading to maternal hypovolemia and hypotension.

Maternal coagulopathy:
Disorders of coagulation and defective hemostasis also preclude the use of
spinal analgesia. Advise  against epidural analgesia is usually  given if the platelet count is below 100,000/µL.  But no cases were found in which bleeding was caused by regional analgesia in thrombocytopenic women. Actually this method is recommended than general anesthesia as in the latter it may become difficult to intubate or ventilate.
The conclusion is  that women with platelet counts of 50,000 to 100,000/µL may be
considered as potential candidates for regional analgesia.

Women on anticoagulation:
If  women receiving anticoagulation therapy  are given regional analgesia are at increased risk for spinal cord hematoma and compression
Recommendations  for the women taking anticoagulants:
·         Women receiving unfractionated heparin therapy with a normal activated partial thromboplastin time (aPTT) and women receiving prophylactic doses of unfractionated heparin or low-dose aspirin can be offered regional analgesia.
·         In  women receiving once-daily low-dose low-molecular-weight heparin, regional analgesia can be given 12 hours after the last injection. And  low-molecular-weight heparin should be withheld for at least 2 hours after the removal of an epidural catheter.
·         No sufficient data is available regarding the safety of regional analgesia in women receiving twice-daily low-molecular-weight heparin  and it is not known whether delaying regional analgesia for 24 hours after the last injection is adequate.


Untreated bacteremia:
If patient having generalized bacterial infection better not to give epidural anesthesia.

Infection over the site of needle placement:
Epidural puncture is contraindicated when the skin or underlying tissue at the site of needle entry is infected.

Neurological disorders:
These disorders  are considered to be contraindications as they may sometimes become
exacerbated because of  anesthetic agent.
Presence of any mass lesion causing increased intracranial pressure is also contraindication for epidural anesthesia.
Also if patient undergone any spinal surgery previously like laminectomy to be enquired before  proceeding as it may cause problem in giving anesthesia.


Preeclampsia:
If patient is having  severe preeclampsia if it become further complicated with significant hemorrhage there occurs markedly decreased blood pressure  when subarachnoid analgesia is used.
The conclusion is that with severe preeclampsia, epidural analgesia is preferable than subarachnoid block and general anesthesia. The general anesthesia especially is having inherent risks of difficult intubation due to airway edema and cerebrovascular accidents due to increased blood pressure.

Severe preeclampsia-eclampsia:
 Choosing  ideal labor analgesia for women with severe preeclampsia is a controversial issue. The problems to be considered are hypotension induced by sympathetic blockade and the dangers from pressor agents which are given to correct that hypotension and potential for pulmonary edema following infusion of large volumes of crystalloid.
Problems are there with general anesthesia also as, tracheal intubation may result in severe, sudden hypertension further complicated by pulmonary or cerebral edema or intracranial hemorrhage.
So, nowadays most obstetrical anesthesiologists are using  epidural blockade for labor and
delivery in women with severe preeclampsia. As , epidural analgesia for women with severe preeclampsia-eclampsia can be safely used when specially trained anesthesiologists and obstetricians are responsible for the woman and her fetus.
The conclusion is  labor epidural analgesia can be given in women with hypertensive disorders, but  it should not to be considered as therapy.in many studies epidural analgesia provided superior pain relief without a significant increase in maternal or neonatal complications.

Intravenous  fluid preload:
Aggressive  volume replacement for maintenance of blood pressure increases the risk for pulmonary edema, especially in the first 72 hours postpartum, because though women with severe preeclampsia have remarkably diminished intravascular volume total body water will be increased because of the capillary leak caused by endothelial cell activation. With vigorous intravenous crystalloid therapy cerebral edema  and pharyngolaryngeal edema can also develop.
This problem can be overcome by limiting the crystalloid preload administration and slowly administering dilute solutions of local anesthetic agents, so that  vasodilation produced by epidural blockade is less abrupt.

Epidural Opiate Analgesia:
 Nowadays Injection of opiates into the epidural space to relieve pain from labor has become popular. They act by  interacting with specific receptors in the dorsal horn and dorsal roots. They will stimulate  both cerebral and spinal opioid receptors.
Normally opiates are given with a local anesthetic agent such as bupivacaine as alone opiates usually will not provide adequate analgesia.
The major advantages of this combination are the rapid onset of pain relief, a decrease in shivering and less dense motor blockade.
Side effects of opiates are  pruritus and urinary retention. Immediate or delayed respiratory depression can occur which is worrisome.
To abolish these symptoms naloxone intravenously can be given, without affecting the analgesic action. To reduce pruritus,  droperidol can be given epidurally in doses of up to 5 mg.

Combined spinal-epidural techniques:
Nowadays using the combination of spinal and epidural techniques becoming popular in providing rapid and effective analgesia for labor as well as for cesarean delivery.
In this technique an introducer needle is first placed in the epidural space. A small-gauge spinal needle is then introduced through the epidural needle into the subarachnoid space. The above technique is called needle-through-needle technique.
 After placing the needles a single bolus of an opioid, sometimes in combination with a local anesthetic, is injected into the subarachnoid space then the spinal needle is withdrawn and an epidural catheter is  placed.
The subarachnoid opioid bolus gives rapid onset of profound pain relief with virtually no motor blockade and the epidural catheter permits repeated dosing of analgesia. So, the combined method produces excellent immediate pain relief.
Side effects were similar between the two groups. One of them is fetal bradycardia without responding to changing maternal position, oxygen administration or intravenous ephedrine  which may not be associated maternal hypotension. This side effect can be minimized by using  fentanyl or with a 2.5-µg dose of sufentanil.


Local infiltration for cesarean delivery:
 Local block may be used as an adjuvant to regional block occasionally  to augment an inadequate or patchy regional block that was given in an emergency. Or it can be used in emergency situations to perform a cesarean to save the life of the fetus in the absence of any anesthesia support.
Technique of local infiltration:
 According to one technique, the skin along the line of the proposed incision is infiltrated then the subcutaneous, muscle and posterior rectus sheath layers are injected after opening  the abdomen. In it a dilute solution of lidocaine  30 mL of 2-percent with 1:200,000 epinephrine diluted with 60 mL of normal saline  is prepared, and a total of 100 to 120 mL is infiltrated.
Better to avoid injection of large volumes into the fatty layers as they are relatively devoid of nerve supply. So, that the total dose of local anesthetic can be limited. Intraperitoneal   manipulations may cause pain, nausea and hypotension, so  each step should be done without haste.
In the  second technique  field block of the major branches supplying the abdominal wall to be done  including the 10th, 11th, and 12th intercostal nerves and the ilioinguinal and genitofemoral nerves.
The  10th, 11th, and 12th intercostal nerves will be located at a point midway between the costal margin and iliac crest in the midaxillary line. The  ilioinguinal and genitofemoral nerves will be found at the level of the external inguinal ring. Only one skin puncture is made at each of the four sites that is two right and two left sides.
To block the intercostals nerves the needle is directed horizontally and injection is carried down to the transversalis fascia, avoiding injection of the subcutaneous fat. Approximately 5 to 8 mL of 0.5-percent lidocaine is injected. The procedure is repeated at a 45-degree angle cephalad and caudad at this site. The other side is then injected.
And to block the ilioinguinal and genitofemoral sites, the injection is started at a site 2 to 3 cm from the pubic tubercle at a 45-degree angle. Then  the skin overlying the planned incision is injected.