- Email: [email protected]
Anesthesia in Modern Obstetrics
Anesthesia in Modern Obstetrics w.
ROBERT PENMAN, M.D.*
WITH the incidence of hospital delivery rising every year, anesthesia is assuming a place of greater importance in obstetric practice. Every woman delivered of a child by a physician in a hospital today demands and is entitled to analgesia or anesthesia for pain relief. In the management of the obstetric case, problems peculiar only to the parturient are encountered, and the physician must be aware of them. In obstetrics he is responsible for the well-being of the unborn child as well as of the mother; and, he must be acquainted with the changes in maternal physiology and 'aware of the effect of these changes on the maternal response to analgesia and anesthesia. Labors, unlike surgical procedures, cannot be' scheduled electively, and at least 50 per cent of deliveries occur at night. Therefore anesthetic requirements cannot be anticipated well in advance, and on many occasions the physician encounters an anesthetist who is not fully acquainted with the anesthetic problems 'peculiar to the pregnant woman. Because of the unpredic,tableness of the onset of labor, the patient frequently enters the hospital in early labor after recently ingesting a full meal. She is, obviously, not an ideal candidate for an analgesic or anesthetic and is subject to all the complications seen in such instances.
EVALUATION OF ANESTHETIC DEATHS
Because of the important position of anesthesia in modern obstetrics, it was felt that a review of the anesthetic deaths reported to the Maternal Mortality Committee of the City of Philadelphia during the past five years would be enlightening. As noted in Table 1, the incidence of anesthetic deaths since 1949 has varied between 11 and 12 per cent. There were twenty-two anesthetic deaths during this five year period, five associated with cesarean section and seventeen with vaginal delivery. In twelve instances an inhalation anesthetic was used. Spinal anesthesia was the agent in seven, caudal in two, and Sodium pentothal in one.
* Associate in Obstetrics and Gynecology, Hahnemann Medical College; Attending Physician, Hahnemann Hospital, Philadelphia. 1551
W. Robert Penman
1552
Eight patients died because of anoxia. In 5 aspiration was the cause of death. In four instances respiratory paralysis, secondary to spinal anesthesia, produced death. Three patients died because of a definite overdosage of spinal anesthesia, and 2 because of intrathecal injection of caudal anesthesia. Eight of the fatal cases were cared for by a staff anesthetist, and 8 patients were anesthetized by a nurse. In the remaining 6 cases, 4 patients were anesthetized by an intern and 2 by a resident. During this five year period anesthesia consistently ranked second or third as the main cause of maternal deaths, with hemorrhage and/or infection as the leading cause. Therefore it is our feeling that the subject of obstetric anesthesia merits sober consideration and discussion. If the problems peculiar to obstetric anesthesia are not recognized and brought to the attention of practising physicians, it is entirely possible that, within the next few years, anesthesia will supplant hemorrhage and infection as the main Table 1
1948
Births ................... 48,123 Deaths .................. 41 Incidence ................ 0.9/1000 Anesthetic deaths ........ 3 Incidence of anesthetic deaths ................. 7.6%
1949
1950
1951
1952
46,836 43 0.9/1000 4
47,516 48 1.0/1000 6
50,318 40 0.8/1000 4
51,661 44 0.9/1000 5
11.1%
11.7%
12.5%
11.1%
cause of maternal death. Because of the importance of this subject, we wish to discuss individually the special problems which confront the physician. MANAGEMENT OF THE NORMAL CASE
Instructions for preparing the patient for the safe use of analgesics and anesthetics should begin early in the prenatal period. Any gross physical defects discerned during the history and physical examination should be corrected. If anemia is found, it too should be eliminated. The patient should be instructed to refrain from eating any solid foods or take liquids hard to digest once she notes the onset of uterine contractions, even if irregular at first. This is most important and cannot be stressed enough. Once labor ensues, gastrointestinal physiology is altered and the emptying time of the stomach is prolonged even more than during pregnancy. In some instances the stomach never completely empties during labor; therefqre, if a large meal is partaken of early in labor, it may form the nucleus for a fatal aspiration of vomitus during the administration of anesthesia.
A nesthesia in Modern Obstetrics
1553
After admission to the hospital the patient should be offered pure liquids by mouth. If additional calories are needed, intravenous glucose should be administered. Once labor is well established and the pain of the contractions is becoming more severe, analgesia should be considered. Demerol, with the dose computed on the basis of 1 mg. per pound of nonpregnant body weight, averaging 100 to 125 mg., in conjunction with an amnesic, such as scopolamine hydrobromide, 0.4 to 0.6 mg. given intramuscularly, provides a satisfactory amnesic-analgesic combination. If the labor is slightly prolonged beyond the average, these agents may be repeated in smaller doses. It is well to avoid additional systemic analgesia if delivery is anticipated within two hours. In those instances in which additional analgesia is required shortly before delivery, we advise inhalations of Trilene, using the "Duke University Inhaler" ( number 3160) or nitrous oxide-oxygen in 50 per cent equal concentrations or even a saddle block type of spinal anesthetic. We strongly believe that these volatile inhalants or the saddle block spinal anesthetic are preferable to the systemic analgesics and prevent fetal respiratory depression at the time of birth. After the patient has received an analgesic, consideration should be given to the problem of anesthesia for delivery. It is at this time that the anesthetist should be consulted. The patient's general condition should be assessed. The type of delivery and the degree of difficulty anticipated should also be discussed. With this approach the anesthetist can safely anesthetize the patient and enable the obstetrician to complete the delivery under conditions optimal to himself, the patient and the newborn baby. Compare this planned approach with the more familiar situation in which obstetrician, patient and anesthetist converge upon the birth room amid mingled confusion, the anesthetist seeing the patient for the first time, the obstetrician ordering that the patient be "Put under," and the patient beseeching to be "knocked out." This results in a stormy induction of anesthesia for the anesthetist and an unsatisfactory delivery for the obstetrician. Under the planned approach a variety of anesthetics may be used, ranging from inhalation anesthesia to conduction types, to local anesthesia, depending on which best suits the needs of patient and obstetrician. We believe that anesthesia is of sufficient importance in obstetrics to warrant individual patient evaluation and discussion well in advance of delivery. All these methods have their individual indications and contraindications and individual advantages and disadvantages. Anesthesia should not be routinized, but individualized with each patient receiving the anesthetic which best suits her and the newborn's needs. It is only in this fashion that obstetric anesthetic mortality can be reduced.
W. Robert Penman
1554
This anesthetic approach is possible in most of the large urban hospitals and, in time, will be available in the smaller community hospitals. But it has been our observation that even in hospitals where anesthetic consultation is available, the obstetricians do not avail themselves of it, thus denying themselves and their patients all the skill and advice which the anesthetist has to offer. At the time of delivery, if the patient is a primigravida and the position and presentation are normal, a saddle-block type of spinal anesthesia is satisfactory. The saddle-block anesthesia should be given in the delivery room. The cervix should be fully dilated and the presenting part just beginning to crown. The membranes should preferably be ruptured. In this instance an outlet forceps delivery may be consummated with ease. The fetus usually breathes and cries rapidly because of the lack of systemic anesthesia, and the blood loss is conspicuously small. The episiotomy may be leisurely repaired without any discomfort to the patient. In addition, the patient is awake and may watch the delivery if she so desires. She also has the great emotional satisfaction of seeing her baby and hearing it cry and is not disturbed by the severe retching and nausea . commonly associated with recovery from inhalation anesthesia. If the patient is a multipara and labor is progressing rapidly, there may be no need or time for a saddle-block type of spinal anesthetic. In this instance inhalation of nitrous oxide and oxygen with a little ether, or cyclopropane, if necessary, will provide adequate anesthesia for a spontaneous delivery. The episiotomy may then be repaired under local infiltration anesthesia or sodium pentothal, as desired by the obstetriClan. SPECIAL PROBLEMS
Management of the Breech Delivery
Once the patient with a breech is well established in labor, she should receive Demerol, 100 to 125 mg., and scopolamine hydrobromide, 0.4 to 0.6 mg. intramuscularly. This may be repeated in four to six hours if necessary and will provide satisfactory analgesia in the average case. Because of the importance of a good uterine contraction pattern and a functional levator ani muscle, lumbar paravertebral block, saddle-block or caudal anesthesia should not be used as analgesic agents in this type of patient. These are excellent pain-relieving agents, but by their very nature they may alter the uterine contraction mechanism and produce an inertia type of labor, or by paralyzing the levator sling they may prolong the second stage of labor. These are problems which should be avoided in breech labors, if possible. For delivery the patient should be taken to the delivery room only after full cervical dilatation has been achieved and the presenting part is
A nesthesia in Modern Obstetrics.
1555
crowning. The anesthetist should be called well in advance and the case discussed. The patient should be prepared and draped for delivery. During this time inhalations of nitrous oxide and oxygen anesthesia should be given with each uterine contraction. The obstetrician should infiltrate the perineum and vaginal mucosa prior to performing an adequate medial laterial episiotomy. After this the patient should be permitted, if possible, to deliver the breech spontaneously to the level of the umbilicus. At this time the anesthetist should be advised (according to a prearranged anesthesia-delivery plan) to deepen the anesthesia, using ether if necessary, in order to facilitate the safe delivery of the shoulders and after-coming head. The deepened anesthesia for the delivery of the shoulders and head is important, for the obstetrician cannot predict in advance the degree of difficulty which will be encountered. If difficulty is encountered, the complete uterine relaxation permits the obstetrician to complete the delivery more efficiently and safely. Once the delivery has been completed, the anesthesia should be stopped and the patient permitted to breathe pure oxygen. The episiotomy can be repaired painlessly with ease from the residual anesthesia produced by the local infiltration prior to delivery. Spinal or caudal anesthesia should never be used for the delivery of a breech. Under both these anesthetics the uterus maintains its tonus and contraction pattern. If shoulder or after-coming head dystocia is encountered, the uterine tonus makes the delivery of these parts more difficult and, in tum, will increase fetal mortality. At present many breech deliveries are made under spinal and caudal anesthesia. As long as the infants are of average size and the pelvic capacity is adequate or large, no difficulty will be enco)lntered; but if the infant is large or if the pelvic measurements are borderline or smaller, difficulty with the delivery of the shoulders or after-coming head will be encountered and may be magnified by the anesthetic to the point at which the infant may unnecessarily die. When a decomposition and extraction of a frank breech is indicated, the problem of anesthesia should be discussed well in advance with the anesthetist. In this instance the obstetrician needs complete uterine relaxation, which can be achieved only with deep ether anesthesia, the anesthetist carrying the patient to the level of the third plane of the third stage of anesthesia. With this type of anesthesia the obstetrician can perform the intrauterine manipulations with relative ease and without fear of rupture of the uterus. ManageInent of PreInature Labor and Delivery
The woman in premature labor presents herself as a special problem to both the obstetrician and the anesthetist. The fetus which she will
1556
W. Robert Penman
eventually deliver will most likely be premature and, as such, subject to all the complications of prematurity. This fetal problem can be magnified by the injudicious use of analgesics and anesthetics during labor and delivery. Once the woman has gone into premature labor, it is our feeling that no analgesics should be used. Any analgesic agent given systemically to the mother will be transmitted directly to the fetus and may seriously depress the fetal respiratory center at the time of birth. It is not necessary, however, for the woman in premature labor to be deprived of all pain-relieving agents. We feel that this is the ideal situation for the use of regional or conduction anesthetics. Recently we have been using lumbar paravertebral block anesthesia for pain relief in these cases. The block is administered when the patient is definitely established in labor and the cervix is 4 to 5 cm. dilated. Onehalf hour prior to administration of the block, we give 100 mg. of N embutal as a precautionary measure against Intracaine sensitivity. The blocks are performed in the labor room, the patient sitting on the side of the labor bed with her back arched. The injection is made at the level of the second lumbar vertebra. The crests of the ileum correspond with the fourth lumbar vertebra, and we use them as a point of reference. Reference points are made on both the left and right sides of the second lumbar vertebra, four fingerbreadths from the superior border of the spine. The skin area is then painted with a suitable antiseptic. Skin wheals are made with 1 per cent Intracaine solution on each side, directly over the previously described reference points. An 8-inch, 20-gauge needle, with a stylet, is then inserted through the skin wheal and directed toward the median line. The needle is permitted to touch the vertebral body and then is angled anteriorly so that the tip slides off the vertebral body and advances about 1 cm. further. In the average patient the needle is about 3% to 4 inches from the skin. This procedure is repeated on the opposite side, and then the stylets are removed. After careful aspiration to exclude blood and/or cerebrospinal fluid, 25 cc. of a 1 per cent Intracaine solution are injected. If blood or cerebrospinal fluid is obtained after the stylet has been removed, the needle is withdrawn 1 cm. This corrects the original error, and the procedure may then be continued with caution. After the initial bilateral injection of the Intracaine, polyethylene catheters may be inserted through the lumen of the needles, so that the tips of the catheters are situated alongside the lumbar sympathetic chain. The needles are then removed over the catheters, which are left in place and covered with sterile dressings. Reinjections of 25 cc. of 1 per cent Intracaine are made bilaterally through the tubing, using aseptic technique. The frequency of injection depends upon the duration of the anesthesia, which usually lasts from
A nesthesia in Modern Obstetrics
1557
one to four hours. In many instances the patient notes only rectal and pelvic pressure in the second stage. It does not produce perineal anesthesia, so that supplementary anesthesia is necessary for delivery. The catheters are removed after the delivery. Another safe method of producing analgesia during premature labor is the use of saddle block anesthesia. When the cervix is 4 to 5 cm. dilated and the patient in progressive labor, she is taken to the delivery room and a saddle block type of spinal anesthesia is given. We use 5 mg. of Pontocaine weighted with 2.1 cc. of 10 per cent dextrose solution. The injection is made with a 20- or 22-gauge needle through the fourth lumbar interspace. The patient is maintained in the upright position for thirty seconds after the injection and then is permitted to lie fiat with a pillow under her head. Sensory anesthetic levels to the tenth to twelfth thoracic segments are obtained with this method, and the pain of uterine contractions is eliminated. This produces anesthesia for one and one-half to two and one-half hours and frequently provides anesthesia for the vaginal delivery. This, too, produces no deleterious effects upon the fetus. Another technique worthy of consideration in the management of premature labor is continuous caudal anesthesia. We very rarely use it because the techniques described have proved satisfactory in our hands and also because the caudal techniques tie up our personnel for prolonged periods. In experienced hands, when there is an adequate supply of personnel, caudal anesthesia has proved to be valuable in the management of this problem. ManagelIlent of the ToxelIlic Patient
The toxemic patient is a problem from the time she enters the hospital, but the anesthetic aspects of her problem are frequently just as important as the medical ones. Because of the extreme l1ibility of the vasomotor system in the toxemic patient, conduction anesthesia must be used with great discretion. The patient's blood pressure level is an excellent criterion in determining the safe use of conduction types of anesthesia in this group of patients. If the blood pressure is in the borderline range of 140/90, saddle block type of spinal anesthesia may be used with safety; but if the blood pressure level is around 150/100 or greater, spinal anesthesia is potentially dangerous, and other forms of anesthesia should be used. Severe drops in blood pressure with spinal anesthesia have been noted on a sufficient number of occasions to make its frequent use in this patient group hazardous to both mother and infant. We feel that paravertebral block analgesia is contraindicated in the toxemic patient because of this latent vasomotor instability. The safest type of anesthesia for these patients is local infiltration or
1558
w.
Robert Penman
pudendal block anesthesia. We use procaine or Intracaine in 0.5 to 1 per cent concentrations. In conjunction with this the patient should be well sedated. Morphine in 10- to 16-mg. doses with 50 per cent solution of magnesium sulfate 10 to 18 cc. intramuscularly produces excellent analgesia. Scopolamine should never be used as an amnesic in the toxemia group because of its central stimulant action, which could initiate the convulsant state. It also produces a tachycardia and an increase in cardiac output, neither of which is desirable in this condition. If an inhalation anesthetic is indicated, ether is the agent of choice. The toxemic patient tolerates ether better than any of the other volatile agents. Managelllent of the Bleeding Patient
Hemorrhage is encountered frequently in a busy obstetric practice and, as mentioned earlier in this discussion, has been one of the leading causes of death in the city of Philadelphia during the past five years. When hemorrhage is associated with labor in the last trimester of pregnancy, the physician should have three goals: (1) cessation of bleeding, (2) replacement of blood loss, (3) safe delivery. After the diagnosis has been made and blood replacement is in progress, attention should be directed toward delivery. If the fetus is viable, analgesics, such as morphine and Demerol, should be withheld, because fetal oxygenation may already be in a precarious state because of the blood loss; if potent analgesics are administered, they may depress fetal respiration sufficiently to bring about the demise of the unborn child. For delivery, local block or pudendal block is undoubtedly safest. If an inhalation agent is indicated, ether or cyclopropane anesthesia, along with adequate blood replacement, constitutes the safest form of therapy. Spinal anesthesia is contraindicated in the presence of hemorrhage because it may produce shock. Managelllent of the Cesarean Section Patient
Anesthesia is always a major problem with cesarean section, and many factors must be considered before anyone agent or method is advised. If the patient is in good general physical condition, single dose spinal or fractional spinal anesthesia is excellent. If single dosage spinal anesthesia is used, the dosage should be in the range of 5 to 7 mg. of Pontacaine or its equivalent. Larger doses are not necessary and may be fatal to the mother. With this "single shot technique" in the pregnant woman, even with the small doses recommended, significant blood pressure drops, high sensory anesthetic levels and depressed respiratory action have been
A nesthesia in Modern Obstetrics
1559
noted. Hence we prefer the fractional or continuous spinal technique for anesthesia in cesarean section. The main advantage of this technique is the use of a smaller initial dose, with the addition of small fractional doses at intervals as needed. This permits adequate fetal oxygenation, with a rather stable maternal blood pressure and adequate anesthesia for any type of cesarean section, including the extraperitoneal approach. We do not advise or use spinal or fractional spinal anesthesia, either therapeutically or for anesthesia, in patients with severe benign essential hypertension or severe preeclampsia or eclampsia, because of the inconstant results obtained therapeutically and because of the extreme vasomotor lability seen in these patients. We feel that spinal anesthesia is also contraindicated in cases of bleeding placenta previa and abruptio placentae, in which bleeding or shock may be present as part of the clinical picture. Of course, spinal anesthesia is also not used in patients with dermatologic lesions involving the posterior thoracolumbar area. If the patient has a toxemia or is actively bleeding and a cesarean section is necessary, we believe that local infiltration anesthesia, associated with adequate systemic analgesia, is preferable. If an inhalation anesthetic is deemed advisable, we feel that cyclopropane or ether is best. The patient in this instance should be prepared and draped prior to induction of the anesthesia. Cyclopropane has a distinct advantage over ether in this instance, in that the induction is more rapid and smooth. We do not routinely premedicate our patients prior to cesarean section, because the premedication, when given, is usually administered one to one and one-half hours prior to delivery, and that is just the time when the analgesic is exerting its maximal depressant effect on the fetus. Our only exception to this rule is the patient with severe preeclampsia or eclampsia, when heavy medication is advised and used to combat or prevent convulsions. In this instance we knowingly deliver a fetus who will suffer from respiratory depression, but we deem this preferable to treating or controlling the convulsant state; which may jeopardize the maternal life. We use morphine sulfate, 10 to 16 mg., in association with magnesium sulfate, 50 per cent solution, 12 to 18 cc. intramuscularly, as premedication in these toxemia cases. MISCELLANEOUS COMMENTS
Sodiulll Pentothal
This agent has been advocated in the literature in recent years as terminal anesthesia for vaginal delivery. It has been stated that it is perfectly safe to use, provided delivery can be anticipated within seven to 10 minutes after initiation of the anesthesia. To use this anesthetic safely, one would require a skilled anesthetist and obstetrician. In the
W. Robert Penman
1560
best interest of the mother and infant, an arbitrary time limit should never be placed upon a vaginal delivery. Therefore, we do not believe that sodium pentothal should be used as an anesthetic for vaginal delivery; but it may be used profitably in conjunction with local infiltration anesthesia for cesarean sections, the pentothal being given just as the uterus is about to be opened. It provides excellent supplemental anesthesia and has no deleterious effect on the fetus. Curare
Curare uniquely does not affect uterine contractibility, and in clinical dosages does not cross the placental barrier. Harmful fetal effects are produced indirectly by anoxia from significant reductions in maternal blood pressure. Because of these unique properties it was thought that curare would be of value in obstetric anesthesia. But from a practical viewpoint there is no real indication for its use in conjunction with vaginal delivery, and skeletal muscle relaxation is never a problem at the time of cesarean section. Therefore curare is rarely used in obstetrics today. SUMMARY
In summary, it has been shown that anesthesia today presents one of the main causes of maternal mortality, along with hemorrhage and infection. The analgesic and anesthetic agents available to us have been discussed, and a plea has been made for early and frequent consultation with the anesthetist in an attempt to bring better and safer anesthesia to the pregnant woman and thus reduce the anesthesia mortality in obstetrics. 230 North Broad Street Philadelphia 2, Pa.
ROBERT PENMAN, M.D.*
WITH the incidence of hospital delivery rising every year, anesthesia is assuming a place of greater importance in obstetric practice. Every woman delivered of a child by a physician in a hospital today demands and is entitled to analgesia or anesthesia for pain relief. In the management of the obstetric case, problems peculiar only to the parturient are encountered, and the physician must be aware of them. In obstetrics he is responsible for the well-being of the unborn child as well as of the mother; and, he must be acquainted with the changes in maternal physiology and 'aware of the effect of these changes on the maternal response to analgesia and anesthesia. Labors, unlike surgical procedures, cannot be' scheduled electively, and at least 50 per cent of deliveries occur at night. Therefore anesthetic requirements cannot be anticipated well in advance, and on many occasions the physician encounters an anesthetist who is not fully acquainted with the anesthetic problems 'peculiar to the pregnant woman. Because of the unpredic,tableness of the onset of labor, the patient frequently enters the hospital in early labor after recently ingesting a full meal. She is, obviously, not an ideal candidate for an analgesic or anesthetic and is subject to all the complications seen in such instances.
EVALUATION OF ANESTHETIC DEATHS
Because of the important position of anesthesia in modern obstetrics, it was felt that a review of the anesthetic deaths reported to the Maternal Mortality Committee of the City of Philadelphia during the past five years would be enlightening. As noted in Table 1, the incidence of anesthetic deaths since 1949 has varied between 11 and 12 per cent. There were twenty-two anesthetic deaths during this five year period, five associated with cesarean section and seventeen with vaginal delivery. In twelve instances an inhalation anesthetic was used. Spinal anesthesia was the agent in seven, caudal in two, and Sodium pentothal in one.
* Associate in Obstetrics and Gynecology, Hahnemann Medical College; Attending Physician, Hahnemann Hospital, Philadelphia. 1551
W. Robert Penman
1552
Eight patients died because of anoxia. In 5 aspiration was the cause of death. In four instances respiratory paralysis, secondary to spinal anesthesia, produced death. Three patients died because of a definite overdosage of spinal anesthesia, and 2 because of intrathecal injection of caudal anesthesia. Eight of the fatal cases were cared for by a staff anesthetist, and 8 patients were anesthetized by a nurse. In the remaining 6 cases, 4 patients were anesthetized by an intern and 2 by a resident. During this five year period anesthesia consistently ranked second or third as the main cause of maternal deaths, with hemorrhage and/or infection as the leading cause. Therefore it is our feeling that the subject of obstetric anesthesia merits sober consideration and discussion. If the problems peculiar to obstetric anesthesia are not recognized and brought to the attention of practising physicians, it is entirely possible that, within the next few years, anesthesia will supplant hemorrhage and infection as the main Table 1
1948
Births ................... 48,123 Deaths .................. 41 Incidence ................ 0.9/1000 Anesthetic deaths ........ 3 Incidence of anesthetic deaths ................. 7.6%
1949
1950
1951
1952
46,836 43 0.9/1000 4
47,516 48 1.0/1000 6
50,318 40 0.8/1000 4
51,661 44 0.9/1000 5
11.1%
11.7%
12.5%
11.1%
cause of maternal death. Because of the importance of this subject, we wish to discuss individually the special problems which confront the physician. MANAGEMENT OF THE NORMAL CASE
Instructions for preparing the patient for the safe use of analgesics and anesthetics should begin early in the prenatal period. Any gross physical defects discerned during the history and physical examination should be corrected. If anemia is found, it too should be eliminated. The patient should be instructed to refrain from eating any solid foods or take liquids hard to digest once she notes the onset of uterine contractions, even if irregular at first. This is most important and cannot be stressed enough. Once labor ensues, gastrointestinal physiology is altered and the emptying time of the stomach is prolonged even more than during pregnancy. In some instances the stomach never completely empties during labor; therefqre, if a large meal is partaken of early in labor, it may form the nucleus for a fatal aspiration of vomitus during the administration of anesthesia.
A nesthesia in Modern Obstetrics
1553
After admission to the hospital the patient should be offered pure liquids by mouth. If additional calories are needed, intravenous glucose should be administered. Once labor is well established and the pain of the contractions is becoming more severe, analgesia should be considered. Demerol, with the dose computed on the basis of 1 mg. per pound of nonpregnant body weight, averaging 100 to 125 mg., in conjunction with an amnesic, such as scopolamine hydrobromide, 0.4 to 0.6 mg. given intramuscularly, provides a satisfactory amnesic-analgesic combination. If the labor is slightly prolonged beyond the average, these agents may be repeated in smaller doses. It is well to avoid additional systemic analgesia if delivery is anticipated within two hours. In those instances in which additional analgesia is required shortly before delivery, we advise inhalations of Trilene, using the "Duke University Inhaler" ( number 3160) or nitrous oxide-oxygen in 50 per cent equal concentrations or even a saddle block type of spinal anesthetic. We strongly believe that these volatile inhalants or the saddle block spinal anesthetic are preferable to the systemic analgesics and prevent fetal respiratory depression at the time of birth. After the patient has received an analgesic, consideration should be given to the problem of anesthesia for delivery. It is at this time that the anesthetist should be consulted. The patient's general condition should be assessed. The type of delivery and the degree of difficulty anticipated should also be discussed. With this approach the anesthetist can safely anesthetize the patient and enable the obstetrician to complete the delivery under conditions optimal to himself, the patient and the newborn baby. Compare this planned approach with the more familiar situation in which obstetrician, patient and anesthetist converge upon the birth room amid mingled confusion, the anesthetist seeing the patient for the first time, the obstetrician ordering that the patient be "Put under," and the patient beseeching to be "knocked out." This results in a stormy induction of anesthesia for the anesthetist and an unsatisfactory delivery for the obstetrician. Under the planned approach a variety of anesthetics may be used, ranging from inhalation anesthesia to conduction types, to local anesthesia, depending on which best suits the needs of patient and obstetrician. We believe that anesthesia is of sufficient importance in obstetrics to warrant individual patient evaluation and discussion well in advance of delivery. All these methods have their individual indications and contraindications and individual advantages and disadvantages. Anesthesia should not be routinized, but individualized with each patient receiving the anesthetic which best suits her and the newborn's needs. It is only in this fashion that obstetric anesthetic mortality can be reduced.
W. Robert Penman
1554
This anesthetic approach is possible in most of the large urban hospitals and, in time, will be available in the smaller community hospitals. But it has been our observation that even in hospitals where anesthetic consultation is available, the obstetricians do not avail themselves of it, thus denying themselves and their patients all the skill and advice which the anesthetist has to offer. At the time of delivery, if the patient is a primigravida and the position and presentation are normal, a saddle-block type of spinal anesthesia is satisfactory. The saddle-block anesthesia should be given in the delivery room. The cervix should be fully dilated and the presenting part just beginning to crown. The membranes should preferably be ruptured. In this instance an outlet forceps delivery may be consummated with ease. The fetus usually breathes and cries rapidly because of the lack of systemic anesthesia, and the blood loss is conspicuously small. The episiotomy may be leisurely repaired without any discomfort to the patient. In addition, the patient is awake and may watch the delivery if she so desires. She also has the great emotional satisfaction of seeing her baby and hearing it cry and is not disturbed by the severe retching and nausea . commonly associated with recovery from inhalation anesthesia. If the patient is a multipara and labor is progressing rapidly, there may be no need or time for a saddle-block type of spinal anesthetic. In this instance inhalation of nitrous oxide and oxygen with a little ether, or cyclopropane, if necessary, will provide adequate anesthesia for a spontaneous delivery. The episiotomy may then be repaired under local infiltration anesthesia or sodium pentothal, as desired by the obstetriClan. SPECIAL PROBLEMS
Management of the Breech Delivery
Once the patient with a breech is well established in labor, she should receive Demerol, 100 to 125 mg., and scopolamine hydrobromide, 0.4 to 0.6 mg. intramuscularly. This may be repeated in four to six hours if necessary and will provide satisfactory analgesia in the average case. Because of the importance of a good uterine contraction pattern and a functional levator ani muscle, lumbar paravertebral block, saddle-block or caudal anesthesia should not be used as analgesic agents in this type of patient. These are excellent pain-relieving agents, but by their very nature they may alter the uterine contraction mechanism and produce an inertia type of labor, or by paralyzing the levator sling they may prolong the second stage of labor. These are problems which should be avoided in breech labors, if possible. For delivery the patient should be taken to the delivery room only after full cervical dilatation has been achieved and the presenting part is
A nesthesia in Modern Obstetrics.
1555
crowning. The anesthetist should be called well in advance and the case discussed. The patient should be prepared and draped for delivery. During this time inhalations of nitrous oxide and oxygen anesthesia should be given with each uterine contraction. The obstetrician should infiltrate the perineum and vaginal mucosa prior to performing an adequate medial laterial episiotomy. After this the patient should be permitted, if possible, to deliver the breech spontaneously to the level of the umbilicus. At this time the anesthetist should be advised (according to a prearranged anesthesia-delivery plan) to deepen the anesthesia, using ether if necessary, in order to facilitate the safe delivery of the shoulders and after-coming head. The deepened anesthesia for the delivery of the shoulders and head is important, for the obstetrician cannot predict in advance the degree of difficulty which will be encountered. If difficulty is encountered, the complete uterine relaxation permits the obstetrician to complete the delivery more efficiently and safely. Once the delivery has been completed, the anesthesia should be stopped and the patient permitted to breathe pure oxygen. The episiotomy can be repaired painlessly with ease from the residual anesthesia produced by the local infiltration prior to delivery. Spinal or caudal anesthesia should never be used for the delivery of a breech. Under both these anesthetics the uterus maintains its tonus and contraction pattern. If shoulder or after-coming head dystocia is encountered, the uterine tonus makes the delivery of these parts more difficult and, in tum, will increase fetal mortality. At present many breech deliveries are made under spinal and caudal anesthesia. As long as the infants are of average size and the pelvic capacity is adequate or large, no difficulty will be enco)lntered; but if the infant is large or if the pelvic measurements are borderline or smaller, difficulty with the delivery of the shoulders or after-coming head will be encountered and may be magnified by the anesthetic to the point at which the infant may unnecessarily die. When a decomposition and extraction of a frank breech is indicated, the problem of anesthesia should be discussed well in advance with the anesthetist. In this instance the obstetrician needs complete uterine relaxation, which can be achieved only with deep ether anesthesia, the anesthetist carrying the patient to the level of the third plane of the third stage of anesthesia. With this type of anesthesia the obstetrician can perform the intrauterine manipulations with relative ease and without fear of rupture of the uterus. ManageInent of PreInature Labor and Delivery
The woman in premature labor presents herself as a special problem to both the obstetrician and the anesthetist. The fetus which she will
1556
W. Robert Penman
eventually deliver will most likely be premature and, as such, subject to all the complications of prematurity. This fetal problem can be magnified by the injudicious use of analgesics and anesthetics during labor and delivery. Once the woman has gone into premature labor, it is our feeling that no analgesics should be used. Any analgesic agent given systemically to the mother will be transmitted directly to the fetus and may seriously depress the fetal respiratory center at the time of birth. It is not necessary, however, for the woman in premature labor to be deprived of all pain-relieving agents. We feel that this is the ideal situation for the use of regional or conduction anesthetics. Recently we have been using lumbar paravertebral block anesthesia for pain relief in these cases. The block is administered when the patient is definitely established in labor and the cervix is 4 to 5 cm. dilated. Onehalf hour prior to administration of the block, we give 100 mg. of N embutal as a precautionary measure against Intracaine sensitivity. The blocks are performed in the labor room, the patient sitting on the side of the labor bed with her back arched. The injection is made at the level of the second lumbar vertebra. The crests of the ileum correspond with the fourth lumbar vertebra, and we use them as a point of reference. Reference points are made on both the left and right sides of the second lumbar vertebra, four fingerbreadths from the superior border of the spine. The skin area is then painted with a suitable antiseptic. Skin wheals are made with 1 per cent Intracaine solution on each side, directly over the previously described reference points. An 8-inch, 20-gauge needle, with a stylet, is then inserted through the skin wheal and directed toward the median line. The needle is permitted to touch the vertebral body and then is angled anteriorly so that the tip slides off the vertebral body and advances about 1 cm. further. In the average patient the needle is about 3% to 4 inches from the skin. This procedure is repeated on the opposite side, and then the stylets are removed. After careful aspiration to exclude blood and/or cerebrospinal fluid, 25 cc. of a 1 per cent Intracaine solution are injected. If blood or cerebrospinal fluid is obtained after the stylet has been removed, the needle is withdrawn 1 cm. This corrects the original error, and the procedure may then be continued with caution. After the initial bilateral injection of the Intracaine, polyethylene catheters may be inserted through the lumen of the needles, so that the tips of the catheters are situated alongside the lumbar sympathetic chain. The needles are then removed over the catheters, which are left in place and covered with sterile dressings. Reinjections of 25 cc. of 1 per cent Intracaine are made bilaterally through the tubing, using aseptic technique. The frequency of injection depends upon the duration of the anesthesia, which usually lasts from
A nesthesia in Modern Obstetrics
1557
one to four hours. In many instances the patient notes only rectal and pelvic pressure in the second stage. It does not produce perineal anesthesia, so that supplementary anesthesia is necessary for delivery. The catheters are removed after the delivery. Another safe method of producing analgesia during premature labor is the use of saddle block anesthesia. When the cervix is 4 to 5 cm. dilated and the patient in progressive labor, she is taken to the delivery room and a saddle block type of spinal anesthesia is given. We use 5 mg. of Pontocaine weighted with 2.1 cc. of 10 per cent dextrose solution. The injection is made with a 20- or 22-gauge needle through the fourth lumbar interspace. The patient is maintained in the upright position for thirty seconds after the injection and then is permitted to lie fiat with a pillow under her head. Sensory anesthetic levels to the tenth to twelfth thoracic segments are obtained with this method, and the pain of uterine contractions is eliminated. This produces anesthesia for one and one-half to two and one-half hours and frequently provides anesthesia for the vaginal delivery. This, too, produces no deleterious effects upon the fetus. Another technique worthy of consideration in the management of premature labor is continuous caudal anesthesia. We very rarely use it because the techniques described have proved satisfactory in our hands and also because the caudal techniques tie up our personnel for prolonged periods. In experienced hands, when there is an adequate supply of personnel, caudal anesthesia has proved to be valuable in the management of this problem. ManagelIlent of the ToxelIlic Patient
The toxemic patient is a problem from the time she enters the hospital, but the anesthetic aspects of her problem are frequently just as important as the medical ones. Because of the extreme l1ibility of the vasomotor system in the toxemic patient, conduction anesthesia must be used with great discretion. The patient's blood pressure level is an excellent criterion in determining the safe use of conduction types of anesthesia in this group of patients. If the blood pressure is in the borderline range of 140/90, saddle block type of spinal anesthesia may be used with safety; but if the blood pressure level is around 150/100 or greater, spinal anesthesia is potentially dangerous, and other forms of anesthesia should be used. Severe drops in blood pressure with spinal anesthesia have been noted on a sufficient number of occasions to make its frequent use in this patient group hazardous to both mother and infant. We feel that paravertebral block analgesia is contraindicated in the toxemic patient because of this latent vasomotor instability. The safest type of anesthesia for these patients is local infiltration or
1558
w.
Robert Penman
pudendal block anesthesia. We use procaine or Intracaine in 0.5 to 1 per cent concentrations. In conjunction with this the patient should be well sedated. Morphine in 10- to 16-mg. doses with 50 per cent solution of magnesium sulfate 10 to 18 cc. intramuscularly produces excellent analgesia. Scopolamine should never be used as an amnesic in the toxemia group because of its central stimulant action, which could initiate the convulsant state. It also produces a tachycardia and an increase in cardiac output, neither of which is desirable in this condition. If an inhalation anesthetic is indicated, ether is the agent of choice. The toxemic patient tolerates ether better than any of the other volatile agents. Managelllent of the Bleeding Patient
Hemorrhage is encountered frequently in a busy obstetric practice and, as mentioned earlier in this discussion, has been one of the leading causes of death in the city of Philadelphia during the past five years. When hemorrhage is associated with labor in the last trimester of pregnancy, the physician should have three goals: (1) cessation of bleeding, (2) replacement of blood loss, (3) safe delivery. After the diagnosis has been made and blood replacement is in progress, attention should be directed toward delivery. If the fetus is viable, analgesics, such as morphine and Demerol, should be withheld, because fetal oxygenation may already be in a precarious state because of the blood loss; if potent analgesics are administered, they may depress fetal respiration sufficiently to bring about the demise of the unborn child. For delivery, local block or pudendal block is undoubtedly safest. If an inhalation agent is indicated, ether or cyclopropane anesthesia, along with adequate blood replacement, constitutes the safest form of therapy. Spinal anesthesia is contraindicated in the presence of hemorrhage because it may produce shock. Managelllent of the Cesarean Section Patient
Anesthesia is always a major problem with cesarean section, and many factors must be considered before anyone agent or method is advised. If the patient is in good general physical condition, single dose spinal or fractional spinal anesthesia is excellent. If single dosage spinal anesthesia is used, the dosage should be in the range of 5 to 7 mg. of Pontacaine or its equivalent. Larger doses are not necessary and may be fatal to the mother. With this "single shot technique" in the pregnant woman, even with the small doses recommended, significant blood pressure drops, high sensory anesthetic levels and depressed respiratory action have been
A nesthesia in Modern Obstetrics
1559
noted. Hence we prefer the fractional or continuous spinal technique for anesthesia in cesarean section. The main advantage of this technique is the use of a smaller initial dose, with the addition of small fractional doses at intervals as needed. This permits adequate fetal oxygenation, with a rather stable maternal blood pressure and adequate anesthesia for any type of cesarean section, including the extraperitoneal approach. We do not advise or use spinal or fractional spinal anesthesia, either therapeutically or for anesthesia, in patients with severe benign essential hypertension or severe preeclampsia or eclampsia, because of the inconstant results obtained therapeutically and because of the extreme vasomotor lability seen in these patients. We feel that spinal anesthesia is also contraindicated in cases of bleeding placenta previa and abruptio placentae, in which bleeding or shock may be present as part of the clinical picture. Of course, spinal anesthesia is also not used in patients with dermatologic lesions involving the posterior thoracolumbar area. If the patient has a toxemia or is actively bleeding and a cesarean section is necessary, we believe that local infiltration anesthesia, associated with adequate systemic analgesia, is preferable. If an inhalation anesthetic is deemed advisable, we feel that cyclopropane or ether is best. The patient in this instance should be prepared and draped prior to induction of the anesthesia. Cyclopropane has a distinct advantage over ether in this instance, in that the induction is more rapid and smooth. We do not routinely premedicate our patients prior to cesarean section, because the premedication, when given, is usually administered one to one and one-half hours prior to delivery, and that is just the time when the analgesic is exerting its maximal depressant effect on the fetus. Our only exception to this rule is the patient with severe preeclampsia or eclampsia, when heavy medication is advised and used to combat or prevent convulsions. In this instance we knowingly deliver a fetus who will suffer from respiratory depression, but we deem this preferable to treating or controlling the convulsant state; which may jeopardize the maternal life. We use morphine sulfate, 10 to 16 mg., in association with magnesium sulfate, 50 per cent solution, 12 to 18 cc. intramuscularly, as premedication in these toxemia cases. MISCELLANEOUS COMMENTS
Sodiulll Pentothal
This agent has been advocated in the literature in recent years as terminal anesthesia for vaginal delivery. It has been stated that it is perfectly safe to use, provided delivery can be anticipated within seven to 10 minutes after initiation of the anesthesia. To use this anesthetic safely, one would require a skilled anesthetist and obstetrician. In the
W. Robert Penman
1560
best interest of the mother and infant, an arbitrary time limit should never be placed upon a vaginal delivery. Therefore, we do not believe that sodium pentothal should be used as an anesthetic for vaginal delivery; but it may be used profitably in conjunction with local infiltration anesthesia for cesarean sections, the pentothal being given just as the uterus is about to be opened. It provides excellent supplemental anesthesia and has no deleterious effect on the fetus. Curare
Curare uniquely does not affect uterine contractibility, and in clinical dosages does not cross the placental barrier. Harmful fetal effects are produced indirectly by anoxia from significant reductions in maternal blood pressure. Because of these unique properties it was thought that curare would be of value in obstetric anesthesia. But from a practical viewpoint there is no real indication for its use in conjunction with vaginal delivery, and skeletal muscle relaxation is never a problem at the time of cesarean section. Therefore curare is rarely used in obstetrics today. SUMMARY
In summary, it has been shown that anesthesia today presents one of the main causes of maternal mortality, along with hemorrhage and infection. The analgesic and anesthetic agents available to us have been discussed, and a plea has been made for early and frequent consultation with the anesthetist in an attempt to bring better and safer anesthesia to the pregnant woman and thus reduce the anesthesia mortality in obstetrics. 230 North Broad Street Philadelphia 2, Pa.