CME Module 5: CSE and Mobile Analgesia for Labour Next >

 

CSE and Mobile Analgesia for Labour

 

Introduction

Traditionally, epidural analgesia for labor and delivery has utilized techniques which are associated with dense motor blocks. These methods were implicated as a potential cause for increased rates of operative and instrumental deliveries. They were also suspected to prolong labor. Additionally, they were associated with increased rates of undesirable maternal side effects such as hypotension and urinary retention. Larger doses of local anesthetics were used, increasing potential maternal risks such as local anesthetic overdose and high block. Patients may be more prone to neurologic injuries as a result of their immobility and they generally report lower satisfaction because of the profound motor block. The goals for the ideal labor analgesic include:

  • Analgesia which is rapid in onset, complete and prolonged
  • No impairment of the delivery process in terms of both rate of progress and incidence of operative delivery
  • Lack of motor block or other maternal side-effects
  • Lack of systemic effects on the mother or fetus

 

Low Dose Mobile Epidurals (LDME)

Mobile labor techniques have been advocated over the last decade and have been increasingly studied. These techniques involve either low dose initiation of the epidural using a mixture of dilute local anesthetic and narcotic or a combined spinal epidural (CSE) as well as maintenance with a dilute local anesthetic/narcotic solution using either a continuous infusion or patient controlled epidural analgesia (PCEA).

Mobile techniques improve patient satisfaction. Patients are able to ambulate (which for most means to get up and go to the bathroom), have less urinary retention and are more likely to have spontaneous vaginal deliveries and less likely to have instrumental deliveries. This effect has been well illustrated by a recent meta-analysis which combined the results of four studies which compared LDME to traditional techniques involving bupivacaine concentrations in excess of 0.125%.



Figure 1.
Instrumental Delivery
Figure 2.
Spontaneous Vaginal Delivery
 

Figures 1 and 2 show the individual and combined odds ratios for instrumental deliveries and spontaneous vaginal deliveries, both of which statistically favor low dose techniques. The numbers needed to treat were 12.5 and 15 respectively. This means that that if you use low dose techniques instead of high dose techniques, you need to treat 12.5 patients to prevent 1 extra instrumental delivery and you need to treat 15 patients to gain one extra spontaneous vaginal delivery.

Table 1 shows that apart from an increased incidence of pruritus (as a result of the increased use of neuraxial narcotics) in the low dose group, there were no other significant differences between the groups for other maternal and neonatal outcomes.



Table 1. Other Maternal and Neonatal Outcomes

Outcome Studies Included Low Dose n/N High Dose n/N OR or WMD (95% Cl) P Value
C/S 10-13 308/1344 157/783 OR 1.08
(0.864, 1.34)
p=0.51
Nausea 11,12 17/589 10/342 OR 1.22
(0.520, 2.85)
p=0.65
Pruritus 11,12 261/589 23/342 OR 10.39
(6.59, 16.39)
p=0.00
Hypotension 11,12 20/589 11/340* OR 1.63
(0.745, 3.58)
p=0.22
Neonatal Apgar 11-13 2/1303 5/708 OR 1.83
(0.724, 4.63)
p=0.20


Score <7 (at 5 minutes)

 

Table 2. LDME Solutions
Local Anesthetic Concentration Narcotic Concentration
Bupivacaine
0.0625% *
Fentanyl
2 mcg/ml
Bupivacaine
0.08% +
Fentanyl
2 mcg/ml
Ropivacaine
0.1% *
Fentanyl
2 mcg.ml
* MSH Solution    + WCH solution

Low dose techniques are defined by the concentration and amount of local anesthetic which is administered. To use these techniques, an epidural catheter must be sited in the usual manner. This may or may not be followed by a traditional test dose. The epidural is then initiated with 15-20 ml of a low dose solution followed by an infusion of the low dose mixture or a PCEA technique. The solutions used in Toronto at Mt. Sinai Hospital and Women’s College Hospital are shown in Table 2 (the ropivacaine solution has recently been discontinued due to increased cost and lack of evidence of superiority over bupivacaine). These solutions are made up by our pharmacy, under a sterile hood, and stored in a locked cupboard on the labor floor.

This technique is most suitable to patients in early labor. For patients in more advanced labor, this technique is still useful but may be modified. A traditional test dose (3 ml of 2% lidocaine) followed by smaller volumes of a more concentrated local anesthetic such as 5-10 ml of 0.25% bupivacaine are useful as are larger volumes of concentrated, rapid onset local such as 10 ml of 1.5%-2% lidocaine. To minimize the amount of local anesthetic needed, 100 mcg of fentanyl or 20 mcg of sufentanil should be used. These narcotics are rapid in onset and have a local anesthetic sparing effect. Alternatively, these patients are good candidates for initiation using a CSE technique which will be described subsequently. Women who are having dysfunctional labor and dystocia usually have more excessive analgesic demands. These patients need not be anticipated as they select themselves out by requiring more top-ups.

Following initiation of the epidural, routine nursing protocol is followed. This involves frequent blood pressure checks every 2-3 minutes for the first 10-15 minutes followed by every 5-10 minutes for the next 15-20 minutes. Fetal heart rate should be monitored either continuously during this first 30 minutes or at least each time a blood pressure is checked. Patients do not ambulate during this time. After the first 30 minutes, they can ambulate as long as they are assessed by the nurse and found to be strong enough. Patients should be able to climb up a step (step-test) or do a deep knee bend to be able to walk unassisted. They should be accompanied at all times while ambulating.

 

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