The effect of epidural anaesthesia on uterine blood flow (UBF):
The changes in UBF secondary to epidural anaesthesia are due to several factors. These include the drugs used and the effects produced as a result of the technique itself. Clinically, the most important effect is a reduction in perfusion pressure.
Local anaesthetics:
Local anaesthetics in low concentrations have no effect on UBF (2, 3).
Vasoconstrictors:
Epinephrine has both alpha- and beta-adrenergic effects with the predominant effect being determined by the dose. There is no clinically significant reduction in UBF when the usual doses are administered. Transient reductions can be observed when epinephrine is injected intravenously during a test dose. Both intravenous ephedrine and phenylephrine can be used to treat hypotension. Neither will cause a reduction in UBF (4).
Fentanyl:
Epidural fentanyl does not reduce UBF (5).
Epidural analgesia for labour and caesarean section:
Epidural analgesia for labour with or without epinephrine, does not usually reduce UBF in normal or pre-eclamptic patients. Pre-eclamptic parturients who received epidural analgesia had an increase in intervillous blood flow (6, 7, 8, 9, 12, 13, 17) (Chapter 39).
Epidural anaesthesia for caesarean section without epinephrine does not cause any alteration in UBF but there may be a reduction in flow when epinephrine is added (10, 11, 15, 16, 18). There is no change in umbilical blood flow (18).
References:
1. Pater JT. Uteroplacental circulation and respiratory gas exchange.
In: Obstetrical Anesthesia.
Editors Shnider SM, Levinson G.
1987. Williams and Wilkins,
Baltimore pp 14-21.
2. Greiss FC, Still JG, Anderson SC. Effects of local anesthetic agents on the uterine vasculatures and myometrium. Am J Obstet Gynecol 1976; 124:889-899.
3. Biehl D, Shnider SM, Levinson G, Calender K. The direct effects of circulating lidocaine on uterine blood flow and foetal well-being in the pregnant ewe. Can Anaesth Soc J 1977; 24:445-451.
4. Raminathan S, Grant GJ. Vasopressor therapy for hypotension due to epidural anesthesia for cesarean section. Acta Anaesthesiol Scand 1988;32:559-565.
5. Craft JB Jr, Robichaux A, Kim HS, Thorpe DH, Mazel P, Woolf WA, Stolte A. The maternal and fetal cardiovascular effects of epidural fentanyl in the sheep model. Am J Obstet Gynecol 1984; 148:1098-1104.
6. Jouppila R, Jouppila P, Hollmen A, Kuikka J. Effect of segmental extradural analgesia on placental blood flow during normal labour. Br. J. Anaesth 1978; 50:563-567.
7. Jouppila P, Jouppila R, Hollmen A, Koivula A. Lumbar epidural analgesia to improve intervillous blood flow during labor in severe preeclampsia. Obstet Gynecol 1982; 59: 158-161.
8. Hollmen AI, Jouppila R, Jouppila P, Koivula A, Vierola H. Effect of extradural analgesia using bupivacaine and 2-chloroprocaine on intervillous blood flow during normal labour. Br J Anaesth 1982; 54:837-842.
9. Hollmen AI, Jouppila R, Albright GA, Jouppila P, Vierola H, Koivula A. Intervillous blood flow during caesarean section with prophylactic ephedrine and epidural anaesthesia. Acta Anaesthesiol Scand 1984; 28:396-400.
10. Skjolderbrand A, Eklund J, Lunell N-O, Nylund L, Sarby B, Thomstrom S. The effect on uteroplacental blood flow of epidural anaesthesia containing adrenalin for caesarean section. Acta Anaesthesiol Scand 1990; 34:85-89.
11. Skjoldenbrand A, Eklund J, Johansson H, et al. Uteroplacental blood flow measured by placental scintigraphy during epidural anaesthesia for caesarean section. Acta Anaesthsiol Scand 1990; 34:79-84.
12. Hughes AB, Devoe LD, Wakefield ML, Metheny WP. The effects of epidural anesthesia on the Doppler velocimetry of umbilical and uterine arteries in normal term labor. Obstet Gynecol 1990; 75:809-12.
13. Patton DE, Lee W, Miller J, Jones M. Maternal, uteroplacental and fetoplacental hemodynamic and Doppler velocimetric changes during epidural anesthesia in normal labor. Obstet. Gynecol 1991; 77:17-19.
14. Petrikovsky BM, Cohen M, Tancer L. Uterine and umbilical blood flow during cesarean section under epidural anesthesia. Acta Obstet Gynecol Scand 1988; 67:737-740
15. Chestnut DH, Weiner CP, Herrig JE. Effects of intravenously administered 2-chloroprocaine upon uterine artery blood flow velocity in gravid guinea pigs. Anesthesiology 1989;70:305-308.
16. Chestnut DH, Weiner CP, Martin JG, Herrig JE, Wang J. Effect of intravenous epinephrine upon uterine artery blood flow velocities in the pregnant guinea pig. Anesthesiology 1986;65:633-636.
17. Ramos-Santos E, Devoe LD, Wakefield ML, Sherline DM, Metheny WP. The effects of epidural anesthesia on the Doppler velocimetry of umbilical and uterine arteries in normal and hypertensive patients during active term labor. Obstet Gynecol 1991 ;77:20-26.
18. Halpern SH, Glanc P, Myhr T, Ryan ML, Fong K, Amankwah K, Ohlsson A. The effect of epidural anaesthesia for caesarean section on uterine and umbilical blood flow in normal and high risk pregnancies. Can J Anaesth 1994;41: 1057-1062.