The Effect of Low-Dose Oxytocin Infusion on Cerebral Hemodynamics in Pregnant Women

ABSTRACT

We investigated the cerebrovascular effects of continuous infusion of low-dose oxytocin in normal pregnant women undergoing induction of labor. In our prospective observational study, middle cerebral artery velocity was measured with transcranial Doppler ultrasound in 25 healthy, normotensive, nonsmoking patients undergoing induction of labor. No vasoactive drugs were used before or during the study period. Measurements were made at baseline and 15, 30, 60, and 120 minutes after oxytocin initiation. Mean arterial pressure, cerebral perfusion pressure, resistance index, resistance area product, and cerebral flow index at different times were calculated and compared using one-way analysis of variance (ANOVA) for repeated measures or Friedman repeated-measures ANOVA as appropriate, with p < 0.05 regarded as significant. No significant systemic or cerebrovascular changes were noted after oxytocin initiation, and there was no correlation between the dosage administered and any hemodynamic parameter. Induction-dose oxytocin does not significantly affect selected cerebral hemodynamic parameters in the first 2 hours after initiation.

KEYWORDS

Oxytocin - transcranial Doppler - induction - cerebral hemodynamics - cerebral perfusion pressure

REFERENCES

• 1 Jonsson M, Hanson U, Lidell C, Nordén-Lindeberg S. ST depression at caesarean section and the relation to oxytocin dose. A randomised controlled trial.  BJOG. 2010;  117 76-83
• 2 Altura B M, Altura B T. Actions of vasopressin, oxytocin, and synthetic analogs on vascular smooth muscle.  Fed Proc. 1984;  43 80-86
• 3 Weis Jr F R, Markello R, Mo B, Bochiechio P. Cardiovascular effects of oxytocin.  Obstet Gynecol. 1975;  46 211-214
• 4 Miller M E, Davidge S T, Mitchell B F. Oxytocin does not directly affect vascular tone in vessels from nonpregnant and pregnant rats.  Am J Physiol Heart Circ Physiol. 2002;  282 H1223-H1228
• 5 Vedernikov Y P, Betancourt A, Wentz M J, Saade G R, Garfield R E. Adaptation to pregnancy leads to attenuated rat uterine artery smooth muscle sensitivity to oxytocin.  Am J Obstet Gynecol. 2006;  194 252-260
• 6 Suzuki Y, Satoh S, Kimura M et al.. Effects of vasopressin and oxytocin on canine cerebral circulation in vivo.  J Neurosurg. 1992;  77 424-431
• 7 Oyama H, Suzuki Y, Satoh S et al.. Role of nitric oxide in the cerebral vasodilatory responses to vasopressin and oxytocin in dogs.  J Cereb Blood Flow Metab. 1993;  13 285-290
• 8 Katusic Z S, Shepherd J T, Vanhoutte P M. Oxytocin causes endothelium-dependent relaxations of canine basilar arteries by activating V1-vasopressinergic receptors.  J Pharmacol Exp Ther. 1986;  236 166-170
• 9 Lassoff S, Altura B M. Do pial terminal arterioles respond to local perivascular application of the neurohypophyseal peptide hormones, vasopressin and oxytocin?.  Brain Res. 1980;  196 266-269
• 10 Abrams G M, Nilaver G, Recht L R, Haldar J, Zimmerman E A. Hypothalamic oxytocin: a cerebrovascular modulator in man?.  Neurology. 1985;  35 1046-1049
• 11 Stolz-Born G, Widder B, Born J. Vascular effects of oxytocin on human middle cerebral artery determined by transcranial Doppler sonography.  Regul Pept. 1996;  62 37-39
• 12 Belfort M A, Tooke-Miller C, Varner M et al.. Evaluation of a noninvasive transcranial Doppler and blood pressure-based method for the assessment of cerebral perfusion pressure in pregnant women.  Hypertens Pregnancy. 2000;  19 331-340
• 13 Belfort M A, Moise Jr K J. Effect of magnesium sulfate on maternal brain blood flow in preeclampsia: a randomized, placebo-controlled study.  Am J Obstet Gynecol. 1992;  167 661-666
• 14 Aaslid R, Markwalder T M, Nornes H. Noninvasive transcranial Doppler ultrasound recording of flow velocity in basal cerebral arteries.  J Neurosurg. 1982;  57 769-774
• 15 Belfort M A, Tooke-Miller C, Varner M et al.. Evaluation of a noninvasive transcranial Doppler and blood pressure-based method for the assessment of cerebral perfusion pressure in pregnant women.  Hypertens Pregnancy. 2000;  19 331-340
• 16 Evans D H, Levene M I, Shortland D B, Archer L N. Resistance index, blood flow velocity, and resistance-area product in the cerebral arteries of very low birth weight infants during the first week of life.  [published erratum appears in Ultrasound Med Biol 1988;14:309] Ultrasound Med Biol. 1988;  14 103-110
• 17 Williams K P, Wilson S. Evaluation of cerebral perfusion pressure changes in laboring women: effects of epidural anesthesia.  Ultrasound Obstet Gynecol. 1999;  14 393-396
• 18 Belfort M A, Tooke-Miller C, Allen Jr J C et al.. Changes in flow velocity, resistance indices, and cerebral perfusion pressure in the maternal middle cerebral artery distribution during normal pregnancy.  Acta Obstet Gynecol Scand. 2001;  80 104-112
• 19 Zeeman G G, Hatab M, Twickler D M. Maternal cerebral blood flow changes in pregnancy.  Am J Obstet Gynecol. 2003;  189 968-972
• 20 Haigh A L, Kitchin A H, Pickford M. The effect of oxytocin on hand blood flow in man following the administration of an oestrogen and isoprenaline.  J Physiol. 1963;  169 161-166
• 21 Buster J E, Freeman A G, Tataryn I V, Hobel C J. Time trend analysis of unconjugated estriol concentrations in third-trimester pregnancy.  Obstet Gynecol. 1980;  56 743-747