EPIDURAL TEST DOSE - LIDOCAINE 100-MG, NOT CHLOROPROCAINE, IS A SYMPTOMATIC MARKER OF IV INJECTION IN LABORING PARTURIENTS

The authors studied the sensitivity (SN) and specificity (SP) of an ep idural test dose containing either lidocaine 100 mg or 2-chloroprocain e 100 mg as symptomatic markers of intravascular injection in labourin g parturients. In a prospective, double-blind and randomized fashion 4 8 unmedicated and labouring parturients were equally divided into thre e groups. After placement of a lumbar epidural catheter the normal sal ine group (NS) received 5 ml normal saline iv, the lidocaine group (LD ) received lidocaine 100 mg iv and the 2-chloroprocaine group (CH) rec eived 2-chloroprocaine 100 mg iv. All injections were given during ute rine diastole. Within the next one to two minutes a blinded observer r ecorded the patient's perception of the presence of metallic or funny taste, dizziness, and tinnitus. We then calculated SN and SP of each s ymptom (alone and in combination) along with their positive (+) and ne gative (-) predictive value (PV). In both groups no symptom alone reac hed clinically acceptable levels of SN (<87%). Only in the LD group, t innitus+taste and dizziness+taste reached a SN of 100% with a SP of 81 % and 69% respectively. While the -PV was 100% for both groups of symp toms, the +PV reached 42% for tinnitus+taste and 30% for dizziness+tas te. We conclude that lidocaine 100 mg is a sensitive marker of intrava scular injection in labouring parturients, and that tinnitus+taste is the most reliable indicator of intravenous injection.