Phenylephrine clinical trials

Anxiety and Phenylephrine Dosage

Spinal anesthesia is considered gold standard anesthetic technique of choice for cesarean delivery (1). However its use is frequently associated with maternal hypotension, which occurs in up to 71% of cases, without prophylactic treatment(2) Spinal hypotension can lead to unpleasant maternal side effects such as nausea, vomiting and dizziness. In addition, adverse effects on the neonate occur because of reduced uteroplacental blood flow resulting in impaired fetal oxygenation and fetal acidosis. As such, current research recommends the prophylactic use of vasopressors for improved maternal and fetal outcomes(3). The international consensus statement on the management of hypotension during cesarean delivery states, that a prophylactic phenylephrine infusion is superior to bolus administration and should be dose titrated according to blood pressure parameters (4). In according to the international guidelines, in our obstetric anesthesia unit, we use a standardized spinal anesthetic regime protocol with a standardized prophylactic phenylephrine infusion at a rate of 50 mcg/min, with the vasopressor dose titrated according to every minute blood pressure parameters. Spinal anesthesia causes maternal hypotension, resulting from a blockade of sympathetic efferent neurons. Patients with higher baseline sympathetic activation have been known to have more marked hypotension after spinal anesthesia (5, 6) Anxiety causes generalized sympathetic activation (7). In a previous research the investigators showed that preoperative anxiety assessed by VAS had a significant effect on hypotension after spinal anesthesia (8). Study objective: In this study the investigators aim to evaluate the effect of anxiety on the cumulative phenylephrine dosage in women undergoing cesarean delivery under spinal anesthesia with prophylactic phenylephrine infusion. The primary hypothesis is that parturients who suffer from preoperative anxiety measured by a verbal numerical scale (VNS) anxiety score and Spielberger State-Trait Inventory questionnaire, will receive higher cumulative doses of phenylephrine (resulting from higher incidence of maternal hypotension).