- Email: [email protected]
Cerebrospinal fluid pressures during labor
Cerebrospinal fluid pressures during labor GERTIE F. MARX, M.D. YASU OKA, M.D. LOUIS R. ORKIN, M.D. New York, New York
CERE BRos PINAL fluid pressures during labor were previously recorded only for limited durations and, then, with the patients in the lateral position. Franken 1 measured the pressures during first stage labor for two hours by means of a Marcy's capsule and kymograph. McCausland and Holmes, 2 utilizing a water manometer, observed the pressures during the end of second stage labor prior to the administration of spinal anesthesia. In both studies, cerebrospinal fluid pressures were within normal limits in the normal obstetrical patient. Franken stated that contractions per se produced only slight increases but that bearing down with or without contraction resulted in elevations of about 400 mm. of water. McCausland and Holmes reported that during contractions with the patients not bearing down, pressures were slightly to moderately increased, and with the patients actively straining, pressures were markedly elevated. The effects of increasingly strong uterine contractions and the influence of different modalities of anesthesia were not studied. In order to evaluate these two factors, continuous cerebrospinal fluid pressure measurements were made throughout labor in 10 normal primi- or secundigravidas and in one primigravida with pre-eclampsia.
Method
When the cervix was at approximately 4 em. dilatation, a polyethylene catheter ( PE 50) was introduced into the intrathecal space. The patients were placed on a foam rubber pad which was shaped on one side to permit the catheter to "float" freely at all times. Pressures were recorded, by means of a strain gauge (Statham P 23 AA) and a Grass polygraph, with patients in the right lateral recumbent and in the supine positions. Observations were made during the normal progress of labor except that, at intervals, they were asked to bear down actively, during and between myometrial contractions. When the cervices were at 6 to 8 em. dilatation, 6 of the parturients were anesthetized with inhalation agents for periods of 10 minutes or less; an electroencephalographic tracing monitored the depth of anesthesia. Continuous spinal anesthesia was started in the other 5 patients. Five of the parturients had not required sedation prior to the start of the study; the other 6 (including the onewith pre-eclampsia) had received meperidine or meperidine with promethazine and scopolamine within the previous one to 3 hours. Five male patients served as controls. Pressure recordings were calibrated before, during, and after the measurements with a mercury manometer.
From the Department of Anesthesiology, Bronx Municipal Hospital Center-Albert Einstein College of Medicine, Yeshiva University. Supported in part by Grant B-1886 from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, United States Public Health Service.
Results
1. Cerebrospinal fluid pressures between myometrial contractions, in the 10 normal parturients in the supine position, ranged from 160 to 340 mm. of water (average 213
214 Marx, Oka, and Orkin
GOt
NORMAL BREATHI\IG
Am.
D£EP BRf.ATI-l!NG
40
zo 0~
~~
.f\.f ..... "-'-,..;-·,,'-
.-..r-·. .t·,-r-.....r
,.-·-._~· ...
~
Fig. 1. Cerebrospinal fluid pressure changes during normal and deep breathing (upper tracings) and panting with second-stage labor contraction (lower tracing) .
Fig. 2. Cerebrospinal fluid pressure changes during different responses to painful uterine contractions.
!lEARING OOWN-Wilrt CONTRACTION
rtf!ST STAGE
SECOND STAGE
Fig. 3. The influence on cerebrospinal fluid pressure of bearing down with uterine contraction (upper tracings), without contraction (left lower tracing), and in a male control (right upper tracing).
J.
July 15, 1962 Obsl. & Gynec.
250 ± +5 mm. of water), with pressmes helow 200 mm. in 2 women and above 300 mrn. in only one. These values were 70 to 120 nun. of \Vater higher than readings ohtained in the lateral position. Control measurements taken in males reYealed pressures from 205 to 340 mrn. of water (average 270 +5 mm. of water) in the supine position with the same differential pressure decrease in the lateral position. 2. The slow "respiratory" and fast "pulsatory" oscillations of the cerebrospinal fluid pressure were visible in all tracings between contractions. With normal respiration, the fluid pressure oscillations varied from 27 to 54 mm. of water, decreasing during inspiration and increasing during expiration. With panting types of respiration, which were encountered during the second stage of labor, rapid large fluctuations occurred with increases of 250 to 350 mm. of water per breath (Fig. 1). 3. Uterine contractions resulted in an elevation of the cerebrospinal fluid pressure only when the parturient experienced discomfort or pain. As long as a contraction was described as perceptible but painless and the woman remained quietly in her position, a change in pressure did not ensue. Rises in pressure during uterine contraction were found to be proportionate to the intensity of subjective pain which in turn influenced the magnitude of skeletal muscle activity. Three types of responses to myometrial contractions were observed during the first stage of labor: the most common reaction was wiggling of hips and shoulders. next most frequent was whining, and kast frequent was a tensing of the body backward in an opisthotonus-like manner. The average increase in cerebrospinal fluid pressure recorded in the "wiggling" type of response was 160 mm. of water (highest 390 mm.) , and in the "whining" type 175 nun. of water (highest 255 mm.). During tensing of the body, the mean rise amounted to 200 mm. of water (highest 310 mm.) (Fig. 2). 4. During bearing down efforts, elevations in cerebrospinal fluid pressure showed individual variations which were relative to the
Volume 84 Number 2
Cerebrospinal fluid pressures during labor
215
ETHER ANESTHESIA (PATIENT NO. 5)
::~ 20
AfTER
3 Ml NUTES
w~~~~~~~ AfTER
5 MINUTES
\
--~~"-"'
0
Fig. 4. During high-frequency low-voltage EEG activity (light anesthesia), the patient's reaction to uterine contraction is reflected in cerebrospinal fluid pressure changes (left tracing). During the phase of mixed waves (moderate plane of anesthesia), uterine contraction is not associated with cerebrospinal fluid pressure changes (right tracing).
force of straining. In the same patient, there was no difference in the cerebrospinal fluid pressure increase between bearing down during the first stage of labor (with or without uterine contraction) and bearing down after delivery; the average rise was 340 mm. of water above normal. The male controls exhibited similar increases during straining (average rise 360 mm. of water above normal) . During the second stage, bearing down efforts were much more intense and, thus, associated with higher levels of cerebrospinal fluid pressure. The average elevation at this stage was measured at 560 mm. of water above normal, and the highest augmentation amounted to 850 mm. of water (Fig. 3). 5. Patients 1 and 2 were anesthetized with nitrous oxide~oxygen in a semiclosed system with carbon dioxide absorption. A 6 L. N 20 : 3 L. 0~ mixture, administered for 10 minutes, did not alter the patients' responses to the uterine contractions or change the pattern of cerebrospinal fluid pressure fluctuations. However, the pressure base line rose rather abruptly in both patients after 3 and 6 minutes, respectively, with the elevations amounting to 80 and 60 mm. of water, respectively. Following an interval of 5 minutes on room air, Patient 1 was reanesthetized with a 6 L. N 2 0 : 2 L. 0 2 mixture for the next 10 minutes. After the first 2 min-
utes, the pressure base line again rose 80 mm. of water. Uterine contractions during the first 6 minutes were associated with the usual degree of "wiggling" and cerebrospinal fluid pressure elevations; two contractions during the last 4 minutes were not accompanied by body movements and there were no cerebrospinal fluid pressure changes. Patient 2 was similarly reanesthetized with SPINAL
ANESTHESIA
f f\OITIENT NO.9
I
~~ ~~,.:;:,.; ~ LEVEL T 3
LEVEL T3
6~ 40~~ 20 NORMAL CONTRACTION AT LEVEL T 10
CONTRACTION WITH BEARING DOWN AT LEVEL T 12
Fig. 5. At a sensory level above T10, the patient felt no pain during uterine contraction and cerebrospinal fluid pressure changes were absent (left upper tracing). Levels below T,o were associated with pain and cerebrospinal fluid pressure fluctuations (left lower tracing). Bearing down effort, performed on command at sensory level of Ta, produced no changes in cerebrospinal fluid pressure (right upper tracing); at sensory level of T,, the usual fluctuations occurred (right lower tracing).
216 Marx, Oka, and Orkin
a 6 L. N 2 0 : 112 L. 0 2 mixture. The pressure base line increased about 60 mm. of water after 3 minutes, and 2 minutes thereafter the fluid pressure ceased to rise during contractions. In both patients, the EEG level was characterized by fast low-voltage activity (light-plane third-stage anesthesia .1 when uterine contractions were no longer temporarily related to specific increases in cerebrospinal fluid pressure. 6. Patients 3 and 4 received cyclopropane in a closed circle absorber system. With a 50 per cent combination with oxygen, uterine contractions stopped after 3 minutes at an EEG level of fast frequency and low voltage with beginning burst suppression (moderate- plane third-stage anesthesia). One half hour later, Patient 4 was reanesthetized with 10 per cent cyclopropane for 10 minutes. There were four uterine contractions during this period. The first was associated with a rist.' in cerebrospinal fluid pressure of 350 mm., the second of 230 nun ..• the third of !60 mm. of water. The fourth contraction was not accompanied by any fluctuations in the fluid pressure, but was preceded by an increase in the pressure base line of 50 mrn. of water. At this time, the EEG showed rhythmical waves of higher voltage and slower frequency (light plane of surgical anesthesia I. 7. Anesthesia was induced in Patient 5 with cyclopropane and maintained with diethyl ether (closed circuit with carbon dioxide absorption). During the 10 minutes of maintenance, the cerebrospinal fluid pressure base line rose from 270 to 350 mm. of water. Uterine contractions occurring after 5 and 7 minutes of ether administration were not associated with fluctuations in fluid pressure. The EEG picture was one of mixed waves of relatively high amplitude and slow frequency (light to moderate plane of anesthesia) (Fig. 4). Thereafter, the uterus did not contract for 12 minutes. Before the next contraction occurred, the pressure base line had returned to 270 mm. of water. Patient 6 was carried through a nitrous oxide, oxygen, ether sequence. It took 9 rninu tes before contractions ceased
July 15, 1%2 Am. J, Obst. & Gynec.
to be accompanied by body movements and cerfbrospinal fluid pressure fluctuations. At this stage, the increase in pressure base line and the EEG pattern Wt.'re comparable to those described for Patient 5. 8. Patients 7 to I 0 were anesthetized with continuous spinal blocks with eithfr tetracaine and dextrose, dibucaine and dextrose, or procaine. The cerebrospinal fluid pressure did not change after administration of the drug. In all patients, sensory anesthesia to a level of T 1 " to T 1, caused unawareness of uterine contractions and sensory anesthesia to a level of 'I\~ to 1' 11 resulted in a painless perception of the contractions. Clinically, the myometrial contractions were forceful, and labor progressed normally. No alterations in cerebrospinal fluid pressure were recorded during the painless uterine contractions. When the sensory level receded below T,", the patients reacted to contractions with the same type of response exhibited prior to the spinal block. A second administration of spinal anesthetic agent led to a repetition of the picture. Bearing down efforts, performed on command with a sensory level below TB, produced the same individual elevations in cerebrospinal fluid pressure as obtained before the anesthesia. With ascending levels from T,. to T,, the force of straining and, thus, the concomitant increases in cerebrospinal fluid pressure were progressively reduced (Fig. 5). 9. The 17 -year-old primigravida with preeclampsia presented with a history of excessive weight gain and recent mild headaches. The blood pressure was 130/88; physical examination and laboratory tests were within normal limits. Cerebrospinal fluid pressures with the patient at rest were recorded at 465 mm. of water in the supint.' position and at 395 mm. of water in the lateral posture. Blood pressure at this time was 130/84 with a pulse rate of 100. During contractions, the patient was wiggling, and the cerebrospinal fluid pressure rose to 510 rnm. of water. At 6 ern. dilatation of the cervix, continuous spinal block anesthesia was begun with tetracaine, 4 mg., and dextrose, 40 mg. A sensory level of T,, was oh-
Volume 84 Number 2
Cerebrospinal fluid pressures during labor 217
tained. The patient started to relax. The cerebrospinal fluid pressure base line gradually decreased to 350 rnm. of water in the supine position; the blood pressure declined simultaneously to 100/60 and the pulse rate to 92. One hour and 45 minutes later, the sensory level had receded to T 12, and the patient began to feel uncomfortable. An injection of tetracaine, 3 mg., and dextrose, 30 mg., afforded pain relief for the next 1 hour and 15 minutes, when a third dose (tetracaine 3 mg., dextrose, 30 mg.) became necessary. During the course of spinal anesthesia and following delivery, cerebrospinal fluid pressure was maintained at 350 mm. of water, while the blood pressure hovered around I 00/60. No vasopressor was required at any time. The patient made an uneventful recovety.
ring in response to the pain of the contraction. The rises in cerebrospinal fluid pressure may, therefore, be prevented by any means affording abolition of pain perception. Inhalation anesthesia commensurate with an EEG pattern of light planes of surgical anesthesia eliminates cerebrospinal fluid pressure increases during contractions; with an EEG level of moderate-depth third-stage anesthesia, uterine contractions are deleted as well. Similarly, regional anesthesia above a sensory level of T 12 prevents conscious pain during myometrial contractions, and elevations in cerebrospinal fluid pressure do not occur. Nevertheless, labor advances in a normal manner. During inhalation anesthesia, increases in the cerebrospinal fluid pressure base line recorded were similar to those observed by other investigators following nitrous oxide, ethyl chloride, cyclopropane, and diethyl ether administration. Woringer, Brogly, and Schneider8 demonstrated a rather abrupt rise from 160 to 260 mm. of water after 5 minutes of anesthesia with an 80 per cent nitrous oxide-20 per cent oxygen mixture. They found an elevation from 150 to over 260 mm. of water after 5 minutes of cyclopropane narcosis, and a gradual increase from 120 to over 280 mm. of water during 19 minutes of ether anesthesia. In our patients, elevations in the cerebrospinal fluid pressure base line began to appear after 3 minutes' inhalation of a 75 per cent nitrous oxide-25 per cent oxygen combination and after 6 minutes of a 10 per cent cyclopropane mixture. During 10 minutes of ether anesthesia, there was a continuous slow increase amounting to 30 per cent above the initial level at the conclusion of the ether administration. The elevations in cerebrospinal fluid pressure base line seen during inhalation anesthesia are related to rises in venous pressure; both pressures were found to change synchronously and with approximately the same amplitude. 8 Resistance in the anesthesia apparatus does not seem to play a role, since inhalation of 100 per cent oxygen in a semiclosed circle absorber system for periods of 10 minutes failed to
Comment
Under normal conditions, cerebrospinal fluid pressure is regulated primarily by the cerebral venous pressure 3 which, in turn, depends upon the systemic venous pressure, the intr"a"ti~oracic pressure, and the carbon dioxide :-.nd oxygen tensions in blood. 4 " 6 All skeletal muscle movements which lead to augmentations in intrathoracic pressure and/ or systemic venous pressure secondarily cause increases in cerebrospinal fluid pressure. With the onset of a straining effort, venous pressure tends to lag somewhat behind the sharply rising cerebrospinal fluid pressure. 6 The more rapid rise in cerebrospinal fluid pressure may result from a transmission of the elevated intrathoracic pressure via the soft tissues 7 or from direct pressure of the dilated vertebral veins on the subarachnoid space. 6 The results of our study confirm the findings of Franken 1 and of McCausland and Holmes2 and demonstrate that, with the normal pregnant woman at term in the supine position, cerebrospinal fluid pressures are also within normal limits. The elevations in cerebrospinal fluid pressure noted during myometrial contractions are not related to the contraction of the uterine musculature, but to movements of skeletal muscles occur-
218 Marx, Oka, and Orkin
change the cerebrospinal fluid pressure.B Increased central venous pressure is known to occur during inhalation narcosis and has been amply demonstrated during the administration of cyclopropane.H', 11 The elevated resting cerebrospinal fluid pressure noted in the pre-eclamptic patient corroborates the findings of other observers who measured pressures of over 500 mm. of water (lateral position reading) in patients suffering from toxemia of pregnancy. 1 " Whenever the original cerebrospinal fluid pressure is high, the magnitude of a change in pressure due to a given change in cerebral blood flow is high} It follows that increases associated with painful uterine contractions or with inhalation anesthesia may lead to precarious levels in patients with elevated resting cerebrospinal fluid pressures and should, therefore, be prevented. Thiopental injections induce a decrease in cerebrospinal fluid pressure,R, "3 but the drug cannot be used for prolonged narcosis in the obstetrical patient because of its rapid transplacental passage with subsequent fetal depression.14 Trichlorethylene is not accompanied by changes in cerebrospinal fluid pressure base line, 8 but the frequently resultant tachypnea leads to large fluctuations of the pressure. Meperidine and alphaprodine have also been reported to cause elevations in cerebrospinal fluid pressure. 1 " Regional anesthesia, on the other hand, does not alter the pressure base line. In addition, spinal or peridural block conducted to the proper sensory level abolishes pain perception during myometrial contractions so that the patient refrains from raising the cerebrospinal fluid pressure by involuntary skeletal muscle movements. Continuous regional block anesthesia may thus be recommended for the management of labor and delivery in patients in whom increased cerebrospinal fluid pressure should be avoided.
July 13, 1962 Am.]. Qb,t. & Gyn.,c.
Summary
Cerebrospinal fiuid pressures were recorded throughout the course of labor in 10 normal parturients and one primigravida with pre-eclampsia. Measurements were made with the patients in the right lateral recumbent and in the supine positions. Bearing down efforts were evaluated during and between myometrial contractions. The influence of \'arious methods of anesthesia on cerebrospinal fluid pressure was studied. In the normal parturient, resting cerebrospinal fluid pressures are within normal limits in the lateral recumbent and in the supine positions; in the pre-eclamptic parturient, the pressure is equally rlevated in both postures. Increases in cerebrospinal fluid pressure during myometrial contractions are not related to contracting uterine musculature per se. but to movements of skeletal muscles occurring in response to the pain of myometrial contraction. Therefore, rises in cerebrospinal fluid pressure during uterine contraction may be prevented by any means affording abolition of pain perception. This may be light third-stage inhalation anesthesia or regional block anesthesia above a sensory level of T 12 • However. most of the commonly used inhalation agents lead to elevations in the cerebrospinal fluid pressure hasP line. Regional block techniques, on the other hand, do not alter cerebrospinal fluid pressure. The problem of additional cerebrospinal fluid pressure increases during uterine contractions and during inhalation anesthesia are discussed with regard to the patient with pathologically elevated cerebrospinal fluid pressure. We wish to thank Dr. Seymour L. Romney, Director of the Department of Ohstetrics and Gynecology, and his resident staff for their cooperation and !"ncouragement.
REFERENCES
1. Franken, H.: Zentralbl. Gynak. 58: 2191, 1934. 2. McCausland, A. M., and Holmes, F.: West. J. Surg. 65: 220, 1957.
3. Wyke, B. D.: In Evans, F. T., and Gray, T. C., editors: General Anaesthesia, London, 1959, Butterworth & Co., chap. 5. 4. Ryder, H. W., Espey, F. F., Kimbell, F. D.,
Volume 84 Number 2
5. 6.
7. 8. 9.
Penka, E. J., Rosenauer, A., Podolsky, B., and Evans, J. P.: A. M. A. Arch. Neurol. & Psychiat. 68: 165, 1952. LaFia, D. L., Chase, H. F., and Kilmore, M. A.: J. Neurosurg. 17: 877, 1960. Berman, A. J., Halpern, A., Shaftel, N., Selman, D., Shaftel, H. E., Kuhn, P. H., Samuels, S. S., and Birch, H. G.: Angiology 2: 437, 1960. Hamilton, W. F., Woodbury, R. A., and Harper, H. T.: J. A. M. A. 107: 853, 1936. Woringer, E., Brogly, G., and Schneider, J.: Anesth. et analg. 8: 649, 1951. Orkin, L. R., and Marx, G. F.: Unpublished data.
Cerebrospinal fluid pressures during labor 219
10. Price, H. L., Conner, J. D., and Dripps, R. D.: Anesthesiology 14: 1, 1953. 11. Thompson, M. C., Patrick, R. T., and Wood, E. H.: J. A. M. A. 164: 389, 1957. 12. Dieckmann, W. J.: The Toxemias of Pregnancy, St. Louis, 1952, The C. V. Mosby Company, chap. 24. 13. Grote, W., and Wii!lenweber, R.: Anaesthesist 9: 201, 1960. 14. Flowers, C. E.: AM. J. OnsT. & GYNEC. 78: 730, 1959. 15. Swerdlow, M.: Anaesthesia 11: 149, 1956. Eastchester Rd. & Morris Park Ave. New York 61, New York
CERE BRos PINAL fluid pressures during labor were previously recorded only for limited durations and, then, with the patients in the lateral position. Franken 1 measured the pressures during first stage labor for two hours by means of a Marcy's capsule and kymograph. McCausland and Holmes, 2 utilizing a water manometer, observed the pressures during the end of second stage labor prior to the administration of spinal anesthesia. In both studies, cerebrospinal fluid pressures were within normal limits in the normal obstetrical patient. Franken stated that contractions per se produced only slight increases but that bearing down with or without contraction resulted in elevations of about 400 mm. of water. McCausland and Holmes reported that during contractions with the patients not bearing down, pressures were slightly to moderately increased, and with the patients actively straining, pressures were markedly elevated. The effects of increasingly strong uterine contractions and the influence of different modalities of anesthesia were not studied. In order to evaluate these two factors, continuous cerebrospinal fluid pressure measurements were made throughout labor in 10 normal primi- or secundigravidas and in one primigravida with pre-eclampsia.
Method
When the cervix was at approximately 4 em. dilatation, a polyethylene catheter ( PE 50) was introduced into the intrathecal space. The patients were placed on a foam rubber pad which was shaped on one side to permit the catheter to "float" freely at all times. Pressures were recorded, by means of a strain gauge (Statham P 23 AA) and a Grass polygraph, with patients in the right lateral recumbent and in the supine positions. Observations were made during the normal progress of labor except that, at intervals, they were asked to bear down actively, during and between myometrial contractions. When the cervices were at 6 to 8 em. dilatation, 6 of the parturients were anesthetized with inhalation agents for periods of 10 minutes or less; an electroencephalographic tracing monitored the depth of anesthesia. Continuous spinal anesthesia was started in the other 5 patients. Five of the parturients had not required sedation prior to the start of the study; the other 6 (including the onewith pre-eclampsia) had received meperidine or meperidine with promethazine and scopolamine within the previous one to 3 hours. Five male patients served as controls. Pressure recordings were calibrated before, during, and after the measurements with a mercury manometer.
From the Department of Anesthesiology, Bronx Municipal Hospital Center-Albert Einstein College of Medicine, Yeshiva University. Supported in part by Grant B-1886 from the National Institute of Neurological Diseases and Blindness, National Institutes of Health, United States Public Health Service.
Results
1. Cerebrospinal fluid pressures between myometrial contractions, in the 10 normal parturients in the supine position, ranged from 160 to 340 mm. of water (average 213
214 Marx, Oka, and Orkin
GOt
NORMAL BREATHI\IG
Am.
D£EP BRf.ATI-l!NG
40
zo 0~
~~
.f\.f ..... "-'-,..;-·,,'-
.-..r-·. .t·,-r-.....r
,.-·-._~· ...
~
Fig. 1. Cerebrospinal fluid pressure changes during normal and deep breathing (upper tracings) and panting with second-stage labor contraction (lower tracing) .
Fig. 2. Cerebrospinal fluid pressure changes during different responses to painful uterine contractions.
!lEARING OOWN-Wilrt CONTRACTION
rtf!ST STAGE
SECOND STAGE
Fig. 3. The influence on cerebrospinal fluid pressure of bearing down with uterine contraction (upper tracings), without contraction (left lower tracing), and in a male control (right upper tracing).
J.
July 15, 1962 Obsl. & Gynec.
250 ± +5 mm. of water), with pressmes helow 200 mm. in 2 women and above 300 mrn. in only one. These values were 70 to 120 nun. of \Vater higher than readings ohtained in the lateral position. Control measurements taken in males reYealed pressures from 205 to 340 mrn. of water (average 270 +5 mm. of water) in the supine position with the same differential pressure decrease in the lateral position. 2. The slow "respiratory" and fast "pulsatory" oscillations of the cerebrospinal fluid pressure were visible in all tracings between contractions. With normal respiration, the fluid pressure oscillations varied from 27 to 54 mm. of water, decreasing during inspiration and increasing during expiration. With panting types of respiration, which were encountered during the second stage of labor, rapid large fluctuations occurred with increases of 250 to 350 mm. of water per breath (Fig. 1). 3. Uterine contractions resulted in an elevation of the cerebrospinal fluid pressure only when the parturient experienced discomfort or pain. As long as a contraction was described as perceptible but painless and the woman remained quietly in her position, a change in pressure did not ensue. Rises in pressure during uterine contraction were found to be proportionate to the intensity of subjective pain which in turn influenced the magnitude of skeletal muscle activity. Three types of responses to myometrial contractions were observed during the first stage of labor: the most common reaction was wiggling of hips and shoulders. next most frequent was whining, and kast frequent was a tensing of the body backward in an opisthotonus-like manner. The average increase in cerebrospinal fluid pressure recorded in the "wiggling" type of response was 160 mm. of water (highest 390 mm.) , and in the "whining" type 175 nun. of water (highest 255 mm.). During tensing of the body, the mean rise amounted to 200 mm. of water (highest 310 mm.) (Fig. 2). 4. During bearing down efforts, elevations in cerebrospinal fluid pressure showed individual variations which were relative to the
Volume 84 Number 2
Cerebrospinal fluid pressures during labor
215
ETHER ANESTHESIA (PATIENT NO. 5)
::~ 20
AfTER
3 Ml NUTES
w~~~~~~~ AfTER
5 MINUTES
\
--~~"-"'
0
Fig. 4. During high-frequency low-voltage EEG activity (light anesthesia), the patient's reaction to uterine contraction is reflected in cerebrospinal fluid pressure changes (left tracing). During the phase of mixed waves (moderate plane of anesthesia), uterine contraction is not associated with cerebrospinal fluid pressure changes (right tracing).
force of straining. In the same patient, there was no difference in the cerebrospinal fluid pressure increase between bearing down during the first stage of labor (with or without uterine contraction) and bearing down after delivery; the average rise was 340 mm. of water above normal. The male controls exhibited similar increases during straining (average rise 360 mm. of water above normal) . During the second stage, bearing down efforts were much more intense and, thus, associated with higher levels of cerebrospinal fluid pressure. The average elevation at this stage was measured at 560 mm. of water above normal, and the highest augmentation amounted to 850 mm. of water (Fig. 3). 5. Patients 1 and 2 were anesthetized with nitrous oxide~oxygen in a semiclosed system with carbon dioxide absorption. A 6 L. N 20 : 3 L. 0~ mixture, administered for 10 minutes, did not alter the patients' responses to the uterine contractions or change the pattern of cerebrospinal fluid pressure fluctuations. However, the pressure base line rose rather abruptly in both patients after 3 and 6 minutes, respectively, with the elevations amounting to 80 and 60 mm. of water, respectively. Following an interval of 5 minutes on room air, Patient 1 was reanesthetized with a 6 L. N 2 0 : 2 L. 0 2 mixture for the next 10 minutes. After the first 2 min-
utes, the pressure base line again rose 80 mm. of water. Uterine contractions during the first 6 minutes were associated with the usual degree of "wiggling" and cerebrospinal fluid pressure elevations; two contractions during the last 4 minutes were not accompanied by body movements and there were no cerebrospinal fluid pressure changes. Patient 2 was similarly reanesthetized with SPINAL
ANESTHESIA
f f\OITIENT NO.9
I
~~ ~~,.:;:,.; ~ LEVEL T 3
LEVEL T3
6~ 40~~ 20 NORMAL CONTRACTION AT LEVEL T 10
CONTRACTION WITH BEARING DOWN AT LEVEL T 12
Fig. 5. At a sensory level above T10, the patient felt no pain during uterine contraction and cerebrospinal fluid pressure changes were absent (left upper tracing). Levels below T,o were associated with pain and cerebrospinal fluid pressure fluctuations (left lower tracing). Bearing down effort, performed on command at sensory level of Ta, produced no changes in cerebrospinal fluid pressure (right upper tracing); at sensory level of T,, the usual fluctuations occurred (right lower tracing).
216 Marx, Oka, and Orkin
a 6 L. N 2 0 : 112 L. 0 2 mixture. The pressure base line increased about 60 mm. of water after 3 minutes, and 2 minutes thereafter the fluid pressure ceased to rise during contractions. In both patients, the EEG level was characterized by fast low-voltage activity (light-plane third-stage anesthesia .1 when uterine contractions were no longer temporarily related to specific increases in cerebrospinal fluid pressure. 6. Patients 3 and 4 received cyclopropane in a closed circle absorber system. With a 50 per cent combination with oxygen, uterine contractions stopped after 3 minutes at an EEG level of fast frequency and low voltage with beginning burst suppression (moderate- plane third-stage anesthesia). One half hour later, Patient 4 was reanesthetized with 10 per cent cyclopropane for 10 minutes. There were four uterine contractions during this period. The first was associated with a rist.' in cerebrospinal fluid pressure of 350 mm., the second of 230 nun ..• the third of !60 mm. of water. The fourth contraction was not accompanied by any fluctuations in the fluid pressure, but was preceded by an increase in the pressure base line of 50 mrn. of water. At this time, the EEG showed rhythmical waves of higher voltage and slower frequency (light plane of surgical anesthesia I. 7. Anesthesia was induced in Patient 5 with cyclopropane and maintained with diethyl ether (closed circuit with carbon dioxide absorption). During the 10 minutes of maintenance, the cerebrospinal fluid pressure base line rose from 270 to 350 mm. of water. Uterine contractions occurring after 5 and 7 minutes of ether administration were not associated with fluctuations in fluid pressure. The EEG picture was one of mixed waves of relatively high amplitude and slow frequency (light to moderate plane of anesthesia) (Fig. 4). Thereafter, the uterus did not contract for 12 minutes. Before the next contraction occurred, the pressure base line had returned to 270 mm. of water. Patient 6 was carried through a nitrous oxide, oxygen, ether sequence. It took 9 rninu tes before contractions ceased
July 15, 1%2 Am. J, Obst. & Gynec.
to be accompanied by body movements and cerfbrospinal fluid pressure fluctuations. At this stage, the increase in pressure base line and the EEG pattern Wt.'re comparable to those described for Patient 5. 8. Patients 7 to I 0 were anesthetized with continuous spinal blocks with eithfr tetracaine and dextrose, dibucaine and dextrose, or procaine. The cerebrospinal fluid pressure did not change after administration of the drug. In all patients, sensory anesthesia to a level of T 1 " to T 1, caused unawareness of uterine contractions and sensory anesthesia to a level of 'I\~ to 1' 11 resulted in a painless perception of the contractions. Clinically, the myometrial contractions were forceful, and labor progressed normally. No alterations in cerebrospinal fluid pressure were recorded during the painless uterine contractions. When the sensory level receded below T,", the patients reacted to contractions with the same type of response exhibited prior to the spinal block. A second administration of spinal anesthetic agent led to a repetition of the picture. Bearing down efforts, performed on command with a sensory level below TB, produced the same individual elevations in cerebrospinal fluid pressure as obtained before the anesthesia. With ascending levels from T,. to T,, the force of straining and, thus, the concomitant increases in cerebrospinal fluid pressure were progressively reduced (Fig. 5). 9. The 17 -year-old primigravida with preeclampsia presented with a history of excessive weight gain and recent mild headaches. The blood pressure was 130/88; physical examination and laboratory tests were within normal limits. Cerebrospinal fluid pressures with the patient at rest were recorded at 465 mm. of water in the supint.' position and at 395 mm. of water in the lateral posture. Blood pressure at this time was 130/84 with a pulse rate of 100. During contractions, the patient was wiggling, and the cerebrospinal fluid pressure rose to 510 rnm. of water. At 6 ern. dilatation of the cervix, continuous spinal block anesthesia was begun with tetracaine, 4 mg., and dextrose, 40 mg. A sensory level of T,, was oh-
Volume 84 Number 2
Cerebrospinal fluid pressures during labor 217
tained. The patient started to relax. The cerebrospinal fluid pressure base line gradually decreased to 350 rnm. of water in the supine position; the blood pressure declined simultaneously to 100/60 and the pulse rate to 92. One hour and 45 minutes later, the sensory level had receded to T 12, and the patient began to feel uncomfortable. An injection of tetracaine, 3 mg., and dextrose, 30 mg., afforded pain relief for the next 1 hour and 15 minutes, when a third dose (tetracaine 3 mg., dextrose, 30 mg.) became necessary. During the course of spinal anesthesia and following delivery, cerebrospinal fluid pressure was maintained at 350 mm. of water, while the blood pressure hovered around I 00/60. No vasopressor was required at any time. The patient made an uneventful recovety.
ring in response to the pain of the contraction. The rises in cerebrospinal fluid pressure may, therefore, be prevented by any means affording abolition of pain perception. Inhalation anesthesia commensurate with an EEG pattern of light planes of surgical anesthesia eliminates cerebrospinal fluid pressure increases during contractions; with an EEG level of moderate-depth third-stage anesthesia, uterine contractions are deleted as well. Similarly, regional anesthesia above a sensory level of T 12 prevents conscious pain during myometrial contractions, and elevations in cerebrospinal fluid pressure do not occur. Nevertheless, labor advances in a normal manner. During inhalation anesthesia, increases in the cerebrospinal fluid pressure base line recorded were similar to those observed by other investigators following nitrous oxide, ethyl chloride, cyclopropane, and diethyl ether administration. Woringer, Brogly, and Schneider8 demonstrated a rather abrupt rise from 160 to 260 mm. of water after 5 minutes of anesthesia with an 80 per cent nitrous oxide-20 per cent oxygen mixture. They found an elevation from 150 to over 260 mm. of water after 5 minutes of cyclopropane narcosis, and a gradual increase from 120 to over 280 mm. of water during 19 minutes of ether anesthesia. In our patients, elevations in the cerebrospinal fluid pressure base line began to appear after 3 minutes' inhalation of a 75 per cent nitrous oxide-25 per cent oxygen combination and after 6 minutes of a 10 per cent cyclopropane mixture. During 10 minutes of ether anesthesia, there was a continuous slow increase amounting to 30 per cent above the initial level at the conclusion of the ether administration. The elevations in cerebrospinal fluid pressure base line seen during inhalation anesthesia are related to rises in venous pressure; both pressures were found to change synchronously and with approximately the same amplitude. 8 Resistance in the anesthesia apparatus does not seem to play a role, since inhalation of 100 per cent oxygen in a semiclosed circle absorber system for periods of 10 minutes failed to
Comment
Under normal conditions, cerebrospinal fluid pressure is regulated primarily by the cerebral venous pressure 3 which, in turn, depends upon the systemic venous pressure, the intr"a"ti~oracic pressure, and the carbon dioxide :-.nd oxygen tensions in blood. 4 " 6 All skeletal muscle movements which lead to augmentations in intrathoracic pressure and/ or systemic venous pressure secondarily cause increases in cerebrospinal fluid pressure. With the onset of a straining effort, venous pressure tends to lag somewhat behind the sharply rising cerebrospinal fluid pressure. 6 The more rapid rise in cerebrospinal fluid pressure may result from a transmission of the elevated intrathoracic pressure via the soft tissues 7 or from direct pressure of the dilated vertebral veins on the subarachnoid space. 6 The results of our study confirm the findings of Franken 1 and of McCausland and Holmes2 and demonstrate that, with the normal pregnant woman at term in the supine position, cerebrospinal fluid pressures are also within normal limits. The elevations in cerebrospinal fluid pressure noted during myometrial contractions are not related to the contraction of the uterine musculature, but to movements of skeletal muscles occur-
218 Marx, Oka, and Orkin
change the cerebrospinal fluid pressure.B Increased central venous pressure is known to occur during inhalation narcosis and has been amply demonstrated during the administration of cyclopropane.H', 11 The elevated resting cerebrospinal fluid pressure noted in the pre-eclamptic patient corroborates the findings of other observers who measured pressures of over 500 mm. of water (lateral position reading) in patients suffering from toxemia of pregnancy. 1 " Whenever the original cerebrospinal fluid pressure is high, the magnitude of a change in pressure due to a given change in cerebral blood flow is high} It follows that increases associated with painful uterine contractions or with inhalation anesthesia may lead to precarious levels in patients with elevated resting cerebrospinal fluid pressures and should, therefore, be prevented. Thiopental injections induce a decrease in cerebrospinal fluid pressure,R, "3 but the drug cannot be used for prolonged narcosis in the obstetrical patient because of its rapid transplacental passage with subsequent fetal depression.14 Trichlorethylene is not accompanied by changes in cerebrospinal fluid pressure base line, 8 but the frequently resultant tachypnea leads to large fluctuations of the pressure. Meperidine and alphaprodine have also been reported to cause elevations in cerebrospinal fluid pressure. 1 " Regional anesthesia, on the other hand, does not alter the pressure base line. In addition, spinal or peridural block conducted to the proper sensory level abolishes pain perception during myometrial contractions so that the patient refrains from raising the cerebrospinal fluid pressure by involuntary skeletal muscle movements. Continuous regional block anesthesia may thus be recommended for the management of labor and delivery in patients in whom increased cerebrospinal fluid pressure should be avoided.
July 13, 1962 Am.]. Qb,t. & Gyn.,c.
Summary
Cerebrospinal fiuid pressures were recorded throughout the course of labor in 10 normal parturients and one primigravida with pre-eclampsia. Measurements were made with the patients in the right lateral recumbent and in the supine positions. Bearing down efforts were evaluated during and between myometrial contractions. The influence of \'arious methods of anesthesia on cerebrospinal fluid pressure was studied. In the normal parturient, resting cerebrospinal fluid pressures are within normal limits in the lateral recumbent and in the supine positions; in the pre-eclamptic parturient, the pressure is equally rlevated in both postures. Increases in cerebrospinal fluid pressure during myometrial contractions are not related to contracting uterine musculature per se. but to movements of skeletal muscles occurring in response to the pain of myometrial contraction. Therefore, rises in cerebrospinal fluid pressure during uterine contraction may be prevented by any means affording abolition of pain perception. This may be light third-stage inhalation anesthesia or regional block anesthesia above a sensory level of T 12 • However. most of the commonly used inhalation agents lead to elevations in the cerebrospinal fluid pressure hasP line. Regional block techniques, on the other hand, do not alter cerebrospinal fluid pressure. The problem of additional cerebrospinal fluid pressure increases during uterine contractions and during inhalation anesthesia are discussed with regard to the patient with pathologically elevated cerebrospinal fluid pressure. We wish to thank Dr. Seymour L. Romney, Director of the Department of Ohstetrics and Gynecology, and his resident staff for their cooperation and !"ncouragement.
REFERENCES
1. Franken, H.: Zentralbl. Gynak. 58: 2191, 1934. 2. McCausland, A. M., and Holmes, F.: West. J. Surg. 65: 220, 1957.
3. Wyke, B. D.: In Evans, F. T., and Gray, T. C., editors: General Anaesthesia, London, 1959, Butterworth & Co., chap. 5. 4. Ryder, H. W., Espey, F. F., Kimbell, F. D.,
Volume 84 Number 2
5. 6.
7. 8. 9.
Penka, E. J., Rosenauer, A., Podolsky, B., and Evans, J. P.: A. M. A. Arch. Neurol. & Psychiat. 68: 165, 1952. LaFia, D. L., Chase, H. F., and Kilmore, M. A.: J. Neurosurg. 17: 877, 1960. Berman, A. J., Halpern, A., Shaftel, N., Selman, D., Shaftel, H. E., Kuhn, P. H., Samuels, S. S., and Birch, H. G.: Angiology 2: 437, 1960. Hamilton, W. F., Woodbury, R. A., and Harper, H. T.: J. A. M. A. 107: 853, 1936. Woringer, E., Brogly, G., and Schneider, J.: Anesth. et analg. 8: 649, 1951. Orkin, L. R., and Marx, G. F.: Unpublished data.
Cerebrospinal fluid pressures during labor 219
10. Price, H. L., Conner, J. D., and Dripps, R. D.: Anesthesiology 14: 1, 1953. 11. Thompson, M. C., Patrick, R. T., and Wood, E. H.: J. A. M. A. 164: 389, 1957. 12. Dieckmann, W. J.: The Toxemias of Pregnancy, St. Louis, 1952, The C. V. Mosby Company, chap. 24. 13. Grote, W., and Wii!lenweber, R.: Anaesthesist 9: 201, 1960. 14. Flowers, C. E.: AM. J. OnsT. & GYNEC. 78: 730, 1959. 15. Swerdlow, M.: Anaesthesia 11: 149, 1956. Eastchester Rd. & Morris Park Ave. New York 61, New York