The Fruit of our Faux Pas: Effect of an Inadvertant Epidural Vein Injection of Lidocaine on Fetal Heart Rate and Uterine Contraction Pattern
Abstract Number: 233
Abstract Type: Case Report/Case Series
Conflicting data exist regarding the direct effects of local anesthetics (LA) on vascular beds and uterine muscle.1,2,3 Little data describes the effects of large doses of LA in vivo in humans. This abstract describes the effect of an inadvertent epidural vein injection of lidocaine on the blood pressure, contraction pattern, and fetal heart rate (FHR) in a laboring patient.
A 112 kg, healthy primip was induced at 40 3/7 weeks after a FHR deceleration during a non-stress test. A senior resident placed an epidural, tested it, and bolused it with 15 divided ml of dilute LA solution. Thirty minutes later, the patient had no detectable sensory-motor block.
After the resident reported an uneventful placement, the decision was made to give 10 ml of 2% lidocaine through the epidural catheter, hoping to produce a definitive anesthetic level. After quick aspiration, all 10 ml of lidocaine was given. Less than 1 min later, the patient reported visual changes. Slower aspiration on the epidural catheter revealed blood. Another minute later, the contraction frequency increased from regular and three minutes apart, to irregular and every minute (see figure). Concomitantly, the FHR decreased to 90 bpm with slow return to baseline. Total episode time was 6 min. Of note, the baseline blood pressure remained unchanged, with mean blood pressures of approximately 100 mmHg. Ephedrine was given late in the episode, and did not change maternal blood pressure.
The epidural was replaced, and the patient delivered vaginally 10 hours later with APGARs of 8 and 9. Hindsight review of the fetal monitoring strip revealed a previously unnoticed increase in maternal heart rate after the epidural test dose.
Our inadvertent IV lidocaine dose gives insight into the effects of larger doses of this LA on the maternal-fetal contraction pattern and perfusion. Maternal blood pressure was unaffected, but uterine contraction frequency was increased. The subsequent decrease in fetal heart tones suggests that placental perfusion was temporarily affected, possibly by decreased uterine diastole, or perhaps by a direct effect on uterine vasculature.
Finally, especially in a larger patient, a positive test dose can be missed. Diligence, and a review of the maternal pulse ox tracing if available, are needed.
1.Chen LK et al. BJA 2006;96:226-30.
2.Fanning RA et al. Anesth & Analg 2008;107:1303-7.
3.Morishima HO et al. AJOG 1979;1