Fetal heart rate after epidural lidocaine and bupivacaine for elective cesarean section

Epinephrine adjuvant reduced epidural blood vessel penetration incidence in a randomized, double-blinded trial

BACKGROUND

Accidental intravascular injection is a significant and potentially devastating risk of epidural block, particularly in parturients whose epidural veins are engorged and hence more easily pierced. This prospective randomized, double-blinded study determined whether the addition of epinephrine to epidural ropivacaine administered by gravity before catheter insertion was associated with fewer epidural catheter blood vessel penetrations.

METHOD

Four hundred and two parturient patients receiving epidural block for elective C/S were randomly allocated to two groups; group I (n = 201) received only ropivacaine 0.75% with fentanyl 5 μg/mL, whereas group II (n = 200) also received epinephrine 5 μg/mL. Both groups received a total of 21 mL anesthetic solution in four increment doses of 3,5,5,5 mL by gravity into the needle through a 22 inch extension tubing before insertion of the closed-end tip catheter. An additional 3 mL of the anesthetic solution was then administered through the catheter.

RESULTS

Epidural epinephrine adjuvant was associated with fewer epidural vessel penetrations (4% vs. 16.5%, P < 0.0001). The addition of epinephrine also significantly reduced catheter insertion problems (12% vs. 23.5%, P-value 0.0024) including the need for catheter readjustment (4.5% vs. 16%, P-value 0.0002) or reinsertion (2.5% vs. 9%, P-value 0.0054). The addition of epinephrine significantly reduced incidence and severity of sedation and had faster onset of surgical block. Sensory level and overall satisfaction did not differ significantly among the groups.

CONCLUSION

The addition of epinephrine to ropivacaine improves the safety and quality of epidural anesthesia when administered by gravity flow via the Hustead needle for cesarean sections.

Effect of epidural analgesia on the fetal heart rate

Fetal heart rate (FHR) changes occasionally follow the use of labor epidurals. Most studies of the phenomenon have focused on specific techniques, but similar timing and appearance suggest a common cause. Induction of analgesia may transiently alter the balance between factors encouraging and inhibiting uterine contractions with subsequent changes of FHR patterns. Regardless the etiology, these changes are transient and do not produce maternal or fetal morbidity. However, they must be promptly recognized and treated if necessary.

Serum bupivacaine concentrations and transplacental transfer following repeated epidural administrations in term parturients during labour

Bupivacaine is the most widely used local anaesthetic in obstetrics for epidural analgesia. Nineteen women (mean age 26.9 +/- 5.3 years) who underwent epidural analgesia during labour were included in this study. All parturients received a first injection of 21.8 +/- 2.5 mg 0.25% plain bupivacaine. The following administrations were given on request: 0.25% concentration was used when cervix uteri was supple, and a 0.375% concentration when it was tonic. Blood samples were collected 5 min after the first injection and then every 30 min until delivery. At delivery blood samples were collected from the infant umbilical cord vein and from the arm vein of the mother. Bupivacaine was assayed by high pressure liquid chromatography. Serum data were analyzed for each patient using a non-compartmental model. Bupivacaine was rapidly detected in serum, and maximal concentration was reached between 5 and 35 min. Pharmacokinetic parameters were estimated in 17 women after the first injection: 87 +/- 35 min for elimination half-life, 60 +/- 19 L for apparent volume of distribution and 0.5 +/- 0.3 L/min for plasmatic clearance. For a mean total duration of labour and total dose administered of respectively 222 +/- 115 min and 57.1 +/- 28.7 mg the mean value of the foeto-maternal ratio was 0.29 +/- 0.10. The infant maximal serum concentration was 0.26 microgram/mL. No side effects were spontaneously reported by the parturients and all infants had an Apgar score of 10 at 5 min after the delivery. We confirm the fast systemic absorption and rapid elimination of bupivacaine which may be used without risk of acute toxicity both in mother and child, even when it is used in a 0.375% concentration.

Placental transfer of lidocaine hydrochloride after prolonged continuous maternal intravenous administration

We treated a patient with arrhythmia during pregnancy with prolonged intravenous administration of lidocaine hydrochloride. This was a case of twin-to-twin transfusion syndrome and the arrhythmia was caused by ritodrine therapy. In total, 14.1 g lidocaine (50 mg.hr-1 for 282 hr) were used. Since there are no descriptions of human placental transfer of lidocaine after such a prolonged continuous intravenous administration, we measured lidocaine concentrations in maternal and fetal serum, and in the amniotic fluid (AF) at delivery. Fetal serum lidocaine concentrations (donor: 0.83 microgram.ml-1; recipient: 0.82 microgram.ml-1) were lower than in the maternal serum (1.6 micrograms.ml-1), while the AF lidocaine concentrations (donor: 1.05 micrograms.ml-1; recipient: 1.04 micrograms.ml-1) were higher than those of the fetal sera. The fetal/maternal concentration ratios of lidocaine were 0.52 for the donor and 0.51 for the recipient, which were similar to those described previously after administration of lidocaine in labour.

Lidocaine hydrocarbonate and lidocaine hydrochloride for cesarean section: transplacental passage and neonatal effects

Twenty-six patients, ASA physical status 1, scheduled for elective cesarean section, were divided at random into two groups and received via an epidural catheter 20 ml of 2.2% lidocaine hydrocarbonate (17.3 mg.ml-1 lidocaine base) with 5 micrograms.ml-1 epinephrine freshly added (Group CO2 = 13 patients) or 20 ml of 2% lidocaine hydrochloride (17.3 mg.ml-1 lidocaine base) also with 5 micrograms.ml-1 epinephrine freshly added. Following clampage of the umbilical cord (at 40.1 +/- 4.9 min after the injection of lidocaine for the CO2 group and at 41.0 +/- 5.4 min for the HCl group), serum concentrations of lidocaine were measured both in the mother and in the umbilical vein. All newborns were examined by the same blinded pediatrician with Apgar scores at 1, 5 and 10 min and with Neurobehavioral Adaptive Capacity Scores (NACS) at 15 min, 2 h and 24 h. The concentrations of lidocaine in the serum were comparable in both groups: in the mothers 8.61 +/- 1.48 mumol.l-1 for the CO2 group vs 8.04 +/- 2.36 mumol.l-1 for the HCl group and in the newborns 3.86 +/- 0.84 mumol.l-1 for the CO2 group vs 3.92 +/- 0.95 mumol.l-1 for the HCl group. The ratio of umbilical vein to maternal vein concentrations of lidocaine was also similar in both groups: 0.45 +/- 0.07 for the CO2 group vs 0.54 +/- 0.24 for the HCl group. The percentage of newborns with a normal NACS (score > or = 35/40) was equal in both groups, i.e. 91% at 15 min and 2 h of life and 100% at 24 h of life.(ABSTRACT TRUNCATED AT 250 WORDS)