Labor results in severe pain for most women. The ideal labor analgesia technique should dramatically reduce the pain of labor, while allowing the parturient to actively participate in the birthing experience. In addition, it should have minimal effect on the fetus or the progress of labor. New labor analgesia techniques approach this goal.
Regional Analgesia for Labor
Of all the possible methods of pain relief which can be used in labor, neuraxial blockade (epidural, spinal, combined spinal-epidural, continuous spinal) provides the most effective and least depressant analgesia. Epidural analgesia via a catheter technique provides excellent pain relief and the ability to extend the duration of the block to match the duration of labor, but it is not “instant” in onset and may be associated with motor block. One-shot spinal analgesia using a lipid soluble opioid is rapid and simple, but is associated with a limited duration of action.
The combination of epidural and spinal anesthesia into one technique, termed “Combined Spinal- Epidural” (CSE), provides the advantages of a spinal (speed of onset, lack of motor block) with the additional flexibility of renewal with an epidural catheter. All three of these regional techniques have advantages and disadvantages and decision about which to use should be individualized to best fit the needs of the individual parturient.
COMBINED SPINAL-EPIDURAL (CSE) ANALGESIA
The first reports of CSE described placing an epidural catheter at one interspace and subsequently initiating a spinal anesthetic at a second interspace (1). CSE provides the fast onset and optimum operative conditions associated with a one-shot spinal but also offers the flexibility of an epidural catheter for extending the duration of the block. The disadvantage of
this technique as it was originally described, was that it necessitated two separate anesthetics at two different interspaces and utilized a “traumatic” spinal needle. The evolution of CSE has been in the direction of a needle-through-needle technique. A recent review article thoroughly describes the evolution of this technique from its introduction to its present use (2).
CSE can be safely used to provide labor analgesia in parturients who are to receive an epidural for labor. There are however, specific patients who will greatly benefit from this technique. These include patients in early or late labor. Patients in early labor can be made comfortable with spinal narcotics (such as sufentanil or fentanyl) which will last for approximately 2-3 hours, during which time the patient will not have a motor block and will be able to ambulate. The major advantage of CSE for patients in late labor is the almost immediate pain relief. Because CSE allows for ambulation of the parturient, it has been called the “walking epidural” (3).
CSE analgesia for labor is usually achieved using a short acting lipid soluble narcotic such as fentanyl or sufentanil. Although morphine has been described as an intrathecal opiate for labor, it has several disadvantages including slow onset, incomplete analgesia, prolonged nausea and pruritus, and delayed respiratory depression. Although pruritus is also associated with lipid soluble opioids, it is usually mild and short lived and does not generally need to be treated. A review of the complications associated with CSE has concluded that CSE is as safe a technique as conventional epidural technique and is associated with greater patient satisfaction (4).
The following opioids are most often used to produce analgesia in the laboring patient: Sufentanil 2.5-10 mcg and Fentanyl 10-25 , even administered via the subarachnoid route, may not always provide adequate analgesia if given to the parturient who is in advanced labor. In cases where the second stage of labor is imminent, the subarachnoid administration of a combination of local anesthetic plus opioid should be considered. The combination of sufentanil 2.5-5 mcg plus bupivacaine 2.5 mg provides rapid analgesia without motor block, alleviates the pain of the second stage of labor, and lasts longer than sufentanil alone (5).
Possible Complications and Side Effects of Intathecal Opioids for Labor
CSE has been reported to be as safe as conventional epidural techniques. Side effects and complications, however, can occur and include the following:
It has been suggested that spinal opioids, perhaps due to their associated decrease in maternal catecholamines, may precipitate uterine hypertonicity and fetal bradycardia (6). Several recent reports have evaluated the incidence of fetal bradycardia and emergency cesarean section following CSE and have not found an increase in these complications(7,8).
Post Dural Puncture Headache
Because the CSE technique includes a dural puncture, there has been concern regarding the
potential for postdural puncture headache (PDPH). The use of small bore "atraumatic" spinal needles will reduce the incidence of PDPH in patients receiving CSE to approximately 1% or less. In addition, it has been suggested that the incidence of unintentional dural puncture is less in CSE patients than in patients receiving conventional epidurals(4). One possible explanation for this finding is that the as part of the CSE technique, the spinal needle may be used for verification of correct placement of the epidural needle when there is inconclusive loss of resistance.
Subarachnoid Migration of the Epidural Catheter
This risk has been extensively studied and does not appear to be a risk of the CSE technique. Holmstrom(9) has found in a cadaver study that it is almost impossible to pass an epidural catheter through a single dural hole made by a 25 g spinal needle. Special epidural needles with a separate port for the spinal needle are now available and should totally prevent the unintentional subarachnoid threading of the epidural catheter. Regardless of needle used, all epidural doses should be incremental.
Respiratory Depression
Sufentanil and fentanyl-induced central respiratory depression has been reported (10). Although respiratory depression might have resulted from potentiation of the respiratory depressant effect of a parenterally administered opioid, respiratory depression following spinal opioids may also occur in patients who have not had parenteral opioids(11). This respiratory depression occurs acutely and therefore any patient receiving CSE must be appropriately monitored for signs of respiratory depression for a period of at least 20 minutes following administration of the subarachnoid opioid.
Basic CSE Technique
The epidural space is identified in the usual fashion. The loss of resistance to saline technique, however, may cause confusion due to misinterpretation of the saline for CSF. Once the epidural space is reached, a long "atraumatic" spinal needle is advanced through the epidural needle until CSF is obtained. Although many combinations of epidural and spinal needles are now available, the spinal needle must protrude past the end of the epidural needle at least 12mm (but optimally 14-18 mm). A syringe is attached to the spinal needle and the subarachnoid drug is administered. The spinal needle is removed, an epidural catheter is inserted into the epidural space and secured. An epidural infusion of dilute local anesthetic (eg, bupivacaine 0.0625%) plus opioid (eg, fentanyl 2-3 mcg/ml) is subsequently initiated.
A patient must remain at bedrest for at least 30 minutes following initiation of CSE. Prior to ambulation, approval must be obtained from the labor nurse, obstetrician, and anesthesiologist. FHR tracing must be within normal limits prior to ambulation. Ambulation is allowed only after the patient has been examined by the anesthesiologist to rule out motor block. A blood pressure measurement taken immediately prior to ambulation while the patient is upright must be within normal limits.
Patients may only ambulate on the labor and delivery suite. Patients may ambulate for no more than 15 minutes at a time before returning to the LDR for BP and FHR monitoring. Ambulating parturients must be supported on one side by a companion and by an iv pole (with wheels) for support on their other side. Under no circumstances may a patient ambulate without an escort.
If a parturient does not wish to ambulate but wants to get out of bed, (or for patients who need to have continuous FHR monitoring), they may be assisted out of bed into the rocking chair adjacent to the bed.
OTHER ADVANCES IN LABOR ANALGESIA
CONTINUOUS INFUSION OF DILUTE LOCAL ANESTHTIC PLUS OPIOID
A major advance in epidural analgesia has been the routine use of continuous infusion of dilute local anesthetics plus lipid soluble opioids by continuous infusion. These infusions have provided better pain relief while producing less motor block. Maternal and neonatal drug concentrations have been tested and continuous infusions have been demonstrated to be safe for both mother and neonate (12). A common infusion for labor analgesia is 0.0625% bupivacaine with 2 mcg /ml fentanyl, with or without epinephrine, infusing at 10-12 ml/hour.
PATIENT CONTROLLED EPIDURAL ANALGESIA (PCEA)
PCEA may provide several advantages, including the ability to minimize drug dosage, flexibility and benefits of self administration, and reduced demand on professional time (13). It has been suggested that this technique may be of great benefit since self control and maintenance of self esteem may be vital to a positive experience in childbirth. It has been suggested that PCEA during labor is now a useful alternative and safe when small doses of dilute bupivacaine are administered with each bolus, reasonable hourly limits are prescribed, and periodic assessments by anesthesiologists are made(14). Controversy still exists regarding the use of a continuous basal infusion in addition to patient controlled boluses. Although basal infusion plus patient demand may be associated with larger doses than if the basal infusion is withheld, the addition of a basal infusion provides for a more even block and may therefore produce greater patient satisfaction.
CONTINUOUS SPINAL ANALGESIA WITH MICROCATHETERS
Due to an association with cauda equina syndrome, spinal microcatheters have been restricted by the FDA. An ongoing multi-institutional study which is being undertaken with FDA approval is evaluating the safety and efficacy of delivering sufentanil and / or bupivacaine into the intrathecal space via a 28g catheter. Although results are still preliminary, to date it appears that continuous spinal analgesia for labor using a 28 g microcatheter is safe and may offer several advantages (15).
References
Regional Analgesia for Labor
Of all the possible methods of pain relief which can be used in labor, neuraxial blockade (epidural, spinal, combined spinal-epidural, continuous spinal) provides the most effective and least depressant analgesia. Epidural analgesia via a catheter technique provides excellent pain relief and the ability to extend the duration of the block to match the duration of labor, but it is not “instant” in onset and may be associated with motor block. One-shot spinal analgesia using a lipid soluble opioid is rapid and simple, but is associated with a limited duration of action.
The combination of epidural and spinal anesthesia into one technique, termed “Combined Spinal- Epidural” (CSE), provides the advantages of a spinal (speed of onset, lack of motor block) with the additional flexibility of renewal with an epidural catheter. All three of these regional techniques have advantages and disadvantages and decision about which to use should be individualized to best fit the needs of the individual parturient.
COMBINED SPINAL-EPIDURAL (CSE) ANALGESIA
The first reports of CSE described placing an epidural catheter at one interspace and subsequently initiating a spinal anesthetic at a second interspace (1). CSE provides the fast onset and optimum operative conditions associated with a one-shot spinal but also offers the flexibility of an epidural catheter for extending the duration of the block. The disadvantage of
this technique as it was originally described, was that it necessitated two separate anesthetics at two different interspaces and utilized a “traumatic” spinal needle. The evolution of CSE has been in the direction of a needle-through-needle technique. A recent review article thoroughly describes the evolution of this technique from its introduction to its present use (2).
CSE can be safely used to provide labor analgesia in parturients who are to receive an epidural for labor. There are however, specific patients who will greatly benefit from this technique. These include patients in early or late labor. Patients in early labor can be made comfortable with spinal narcotics (such as sufentanil or fentanyl) which will last for approximately 2-3 hours, during which time the patient will not have a motor block and will be able to ambulate. The major advantage of CSE for patients in late labor is the almost immediate pain relief. Because CSE allows for ambulation of the parturient, it has been called the “walking epidural” (3).
CSE analgesia for labor is usually achieved using a short acting lipid soluble narcotic such as fentanyl or sufentanil. Although morphine has been described as an intrathecal opiate for labor, it has several disadvantages including slow onset, incomplete analgesia, prolonged nausea and pruritus, and delayed respiratory depression. Although pruritus is also associated with lipid soluble opioids, it is usually mild and short lived and does not generally need to be treated. A review of the complications associated with CSE has concluded that CSE is as safe a technique as conventional epidural technique and is associated with greater patient satisfaction (4).
The following opioids are most often used to produce analgesia in the laboring patient: Sufentanil 2.5-10 mcg and Fentanyl 10-25 , even administered via the subarachnoid route, may not always provide adequate analgesia if given to the parturient who is in advanced labor. In cases where the second stage of labor is imminent, the subarachnoid administration of a combination of local anesthetic plus opioid should be considered. The combination of sufentanil 2.5-5 mcg plus bupivacaine 2.5 mg provides rapid analgesia without motor block, alleviates the pain of the second stage of labor, and lasts longer than sufentanil alone (5).
Possible Complications and Side Effects of Intathecal Opioids for Labor
CSE has been reported to be as safe as conventional epidural techniques. Side effects and complications, however, can occur and include the following:
- Pruritus
- Nausea / Vomiting
- Hypotension
- Urinary retention
- Uterine hyperstimulation and fetal bradycardia
- Maternal Respiratory Depression
It has been suggested that spinal opioids, perhaps due to their associated decrease in maternal catecholamines, may precipitate uterine hypertonicity and fetal bradycardia (6). Several recent reports have evaluated the incidence of fetal bradycardia and emergency cesarean section following CSE and have not found an increase in these complications(7,8).
Post Dural Puncture Headache
Because the CSE technique includes a dural puncture, there has been concern regarding the
potential for postdural puncture headache (PDPH). The use of small bore "atraumatic" spinal needles will reduce the incidence of PDPH in patients receiving CSE to approximately 1% or less. In addition, it has been suggested that the incidence of unintentional dural puncture is less in CSE patients than in patients receiving conventional epidurals(4). One possible explanation for this finding is that the as part of the CSE technique, the spinal needle may be used for verification of correct placement of the epidural needle when there is inconclusive loss of resistance.
Subarachnoid Migration of the Epidural Catheter
This risk has been extensively studied and does not appear to be a risk of the CSE technique. Holmstrom(9) has found in a cadaver study that it is almost impossible to pass an epidural catheter through a single dural hole made by a 25 g spinal needle. Special epidural needles with a separate port for the spinal needle are now available and should totally prevent the unintentional subarachnoid threading of the epidural catheter. Regardless of needle used, all epidural doses should be incremental.
Respiratory Depression
Sufentanil and fentanyl-induced central respiratory depression has been reported (10). Although respiratory depression might have resulted from potentiation of the respiratory depressant effect of a parenterally administered opioid, respiratory depression following spinal opioids may also occur in patients who have not had parenteral opioids(11). This respiratory depression occurs acutely and therefore any patient receiving CSE must be appropriately monitored for signs of respiratory depression for a period of at least 20 minutes following administration of the subarachnoid opioid.
Basic CSE Technique
The epidural space is identified in the usual fashion. The loss of resistance to saline technique, however, may cause confusion due to misinterpretation of the saline for CSF. Once the epidural space is reached, a long "atraumatic" spinal needle is advanced through the epidural needle until CSF is obtained. Although many combinations of epidural and spinal needles are now available, the spinal needle must protrude past the end of the epidural needle at least 12mm (but optimally 14-18 mm). A syringe is attached to the spinal needle and the subarachnoid drug is administered. The spinal needle is removed, an epidural catheter is inserted into the epidural space and secured. An epidural infusion of dilute local anesthetic (eg, bupivacaine 0.0625%) plus opioid (eg, fentanyl 2-3 mcg/ml) is subsequently initiated.
A patient must remain at bedrest for at least 30 minutes following initiation of CSE. Prior to ambulation, approval must be obtained from the labor nurse, obstetrician, and anesthesiologist. FHR tracing must be within normal limits prior to ambulation. Ambulation is allowed only after the patient has been examined by the anesthesiologist to rule out motor block. A blood pressure measurement taken immediately prior to ambulation while the patient is upright must be within normal limits.
Patients may only ambulate on the labor and delivery suite. Patients may ambulate for no more than 15 minutes at a time before returning to the LDR for BP and FHR monitoring. Ambulating parturients must be supported on one side by a companion and by an iv pole (with wheels) for support on their other side. Under no circumstances may a patient ambulate without an escort.
If a parturient does not wish to ambulate but wants to get out of bed, (or for patients who need to have continuous FHR monitoring), they may be assisted out of bed into the rocking chair adjacent to the bed.
OTHER ADVANCES IN LABOR ANALGESIA
CONTINUOUS INFUSION OF DILUTE LOCAL ANESTHTIC PLUS OPIOID
A major advance in epidural analgesia has been the routine use of continuous infusion of dilute local anesthetics plus lipid soluble opioids by continuous infusion. These infusions have provided better pain relief while producing less motor block. Maternal and neonatal drug concentrations have been tested and continuous infusions have been demonstrated to be safe for both mother and neonate (12). A common infusion for labor analgesia is 0.0625% bupivacaine with 2 mcg /ml fentanyl, with or without epinephrine, infusing at 10-12 ml/hour.
PATIENT CONTROLLED EPIDURAL ANALGESIA (PCEA)
PCEA may provide several advantages, including the ability to minimize drug dosage, flexibility and benefits of self administration, and reduced demand on professional time (13). It has been suggested that this technique may be of great benefit since self control and maintenance of self esteem may be vital to a positive experience in childbirth. It has been suggested that PCEA during labor is now a useful alternative and safe when small doses of dilute bupivacaine are administered with each bolus, reasonable hourly limits are prescribed, and periodic assessments by anesthesiologists are made(14). Controversy still exists regarding the use of a continuous basal infusion in addition to patient controlled boluses. Although basal infusion plus patient demand may be associated with larger doses than if the basal infusion is withheld, the addition of a basal infusion provides for a more even block and may therefore produce greater patient satisfaction.
CONTINUOUS SPINAL ANALGESIA WITH MICROCATHETERS
Due to an association with cauda equina syndrome, spinal microcatheters have been restricted by the FDA. An ongoing multi-institutional study which is being undertaken with FDA approval is evaluating the safety and efficacy of delivering sufentanil and / or bupivacaine into the intrathecal space via a 28g catheter. Although results are still preliminary, to date it appears that continuous spinal analgesia for labor using a 28 g microcatheter is safe and may offer several advantages (15).
References
- Brownridge P: Epidural and subarachnoid analgesia for elective caesarian section.Anaesthesia 36:70, 1981.
- Rawal N, Van Zundert A, Holmstrom B, Crowhurst JA. Combined spinal-epidural technique. Regional Anesthesia 22:406-423, 1997.
- Collis RE, Davies DWL, Aveling W. Randomized comparison of combined spinal epidural and standard epidural analgesia in labour. Lancet 1995;345;1413-1416.
- Norris MC, Grieco WM, Borkowski M, et al. Complications of labor Analgesia: epidural versus combined spinal-epidural techniques. Anesth Analg 1995;79:529-37.
- Campbell DC, Camann WR, Datta S. The addition of bupivacaine to intrathecal sufentanil for labor analgesia. Anesth Analg 81;305-9, 1995
- Clarke VT, Smiley RM, Finster M. Uterine hyperactivity after intrathecal injection of fentanyl for analgesia during labor: A cause of fetal bradycardia? Anesthesiology 81:1083,1994.
- Nielsen PE, Erickson R, Abouleish EI et al. Fetal heart rate changes after intrathecal sufentanil or epidural bupivacaine for labor analgesia: Incidence and clinical significance. Anesth Analg 1996;83:742-6.
- Albright GA, Forester RM. Does combined spinal-epidural analgesia with subarachnoid sufentanil increase the incidence of emergency cesarean delivery? Regional Anesthesia 1997;22:400-405.
- Holmstrom B, Rawal N, Axelsson K,Nydahl P. Risk of catheter migration during combined spinal-epidural block: Percutaneous epiduroscopy study. Anesth Analg 1995;80;747-53.
- Hays RL, Palmer CM. Respiratory depression after intrathecal sufentanil during labor. Anesthesiology 1994;81:511-2.
- Greenlagh CA. Respiratory arrest in a parturient following intrathecal injection of sufentanil and bupivacaine. Anaesthesia 1996:51;173-5.
- Bader AM, Fragneto R, Terui K, et al. Maternal and neonatal fentanyl and bupivacaine concentrations after epidural infusion during labor. Anesth Analg 1995;81:829-32.
- Paech MJ. Patient-controlled epidural analgesia in obstetrics. Int J Obstet Anesthesia 1996:5;115-125.
- Ferrante FM, Rosinia FA, Gordon C et al. The role of continuous background infusions in patient-controlled epidural analgesia for labor and delivery. Anesth Analg 1994;79:80-84.
- Eisenach JC. Patient-controlled epidural analgesia during labor, or whose finger do you want on the button? Int J Obstet Anesthesia 1993:2:63-64.
- Arkoosh VA, Palmer CM, Van Maren GA, Yun Em, Wissler RN. Anesthesiology Supplement , April 1998:A8.
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