The Epidural Test Dose: A Review

Abstract

This review systematically examines the literature on the ability of the classical epidural test dose and other strategies to detect intravascular, intrathecal, or subdural epidural needle/catheter misplacement. For detection of simulated intravascular misplacements, a sensitivity (S) and a positive predictive value (PPV) > or =80 demonstrated by at least two randomized controlled trials coming from two different centers were determined for the following tests and patient populations: Nonpregnant adult patients = increase in systolic blood pressure (SBP) > or =15 mm Hg (S = 80-100 and 93-100; PPV = 80-100 and 83-100) or either an increase in SBP > or =15 mm Hg or an increase in heart rate > or =10 bpm after the injection of 10 (S = 100; PPV = 83-100) or 15 microg of epinephrine (S = 100; PPV = 83-100); pregnant patients = sedation, drowsiness, or dizziness within 5 min after the injection of 100 microg of fentanyl (S = 92-100; PPV = 91-95); and children = increase in SBP > or =15 mm Hg after the injection of 0.5 microg/kg of epinephrine (S = 81-100; PPV = 100). Conversely, more studies are required to determine the best strategies to detect intrathecal and subdural epidural needle/catheter misplacements in these three patient populations.

Local anesthetic systemic toxicity: Continuing Professional Development

“…The hemodynamic response is attenuated, however, in patients on beta-blockers, 37 the elderly, and patients who are sedated or under general anesthesia. 38 Its use in labour epidural analgesia is also controversial due to the possibility of false-positive results from simultaneous uterine contractions and a lower threshold for increases in heart rate, as well as concerns of exacerbating hypertension in preeclampsia. 38 While there has been a recent trend to avoid epinephrine in peripheral nerve blockade because of concerns that local vasoconstriction may exacerbate neurotoxicity, this has yet to be clinically proven.…”

“…38 Its use in labour epidural analgesia is also controversial due to the possibility of false-positive results from simultaneous uterine contractions and a lower threshold for increases in heart rate, as well as concerns of exacerbating hypertension in preeclampsia. 38 While there has been a recent trend to avoid epinephrine in peripheral nerve blockade because of concerns that local vasoconstriction may exacerbate neurotoxicity, this has yet to be clinically proven. Finally, epinephrine has the additional advantage of reducing peak LA plasma concentration, 39 and thus, on balance, the advantages of epinephrine far outweigh its limitations and potential risks.…”

“…La réponse hémodynamique est cependant atténuée chez les patients prenant des bêtabloquants, 37 chez les patients âgés et ceux qui sont sous sédation ou sous anesthésie générale. 38 L'utilisation d'épinéphrine dans l'analgésie péridurale pour le travail obstétrical est également controversée en raison de la possibilité de résultats faux positifs provenant de contractions utérines simultanées et d'une réponse accrue de la fréquence cardiaque, ainsi que d'inquiétudes quant à une exacerbation possible de l'hypertension dans les cas de préeclampsie. 38 Bien qu'une tendance récente vise à éviter cet agent dans les blocs nerveux périphériques en raison d'une crainte que la vasoconstriction locale exacerbe sa neurotoxicité, les données probantes cliniques font encore défaut.…”

“…38 L'utilisation d'épinéphrine dans l'analgésie péridurale pour le travail obstétrical est également controversée en raison de la possibilité de résultats faux positifs provenant de contractions utérines simultanées et d'une réponse accrue de la fréquence cardiaque, ainsi que d'inquiétudes quant à une exacerbation possible de l'hypertension dans les cas de préeclampsie. 38 Bien qu'une tendance récente vise à éviter cet agent dans les blocs nerveux périphériques en raison d'une crainte que la vasoconstriction locale exacerbe sa neurotoxicité, les données probantes cliniques font encore défaut. Enfin, l'épinéphrine a l'avantage supplémentaire de réduire les concentrations plasmatiques maximales d'AL, 39 ce qui, tout bien considéré, rend les avantages de l'épinéphrine bien plus importants que ses limites et risques potentiels.…”

Thirty years after the bupivacaine controversy: what have we learned?

“…The initial recommendation was that administering an epinephrine-containing test dose could detect an iv needle or catheter. 10 While true in the non-pregnant population, the use of an epinephrine-containing test dose in the parturient has not been universally accepted due to a high false positive rate 11 and the potential to decrease uteroplacental blood flow and prolong labour due to decreased uterine activity.…”