[Accidental spinal anesthesia in obstetrics. Limits of epidural test-dose]

Two cases of accidental spinal anaesthesia occurring in obstetrical patients are reported and discussed. Epidural anaesthesia had been asked for by the women, both being free from any significant medical history. A Tuohy needle was inserted in the midline between L3 and L4 with the patient sitting. The extradural space was identified by the loss of resistance using saline. The test-dose (2 ml and 4 ml of 1% lignocaine respectively) was administered five minutes before changing the patient to the supine position. In the first case, after a test-dose had remained without any effect, 8 ml of 0.25% bupivacaine were injected, about one hour later. The patient rapidly complained of paralysis of her legs and difficulties in breathing. Her blood pressure decreased from 120/80 mmHg to 90/60 mmHg. The upper level of analgesia reached T4. She improved after infusion of 1.51 of lactated Ringer's solution. Endotracheal intubation was not required. Delivery was assisted with a vacuum extractor. In the other patient, when the extradural space had been located, there was a small reflux of clear fluid which did not contain any glucose. As the test-dose did not result in any effect. 2 ml of 2% lignocaine with adrenaline were injected. This was followed by an immediate sensory loss in the legs, extending up to T10. Caesarean section was decided on, without any further injections (foetal macrosomia, breech presentation). Both patients totally recovered without any sequela. Both children had an Apgar score of 10 at 1 and 5 minutes. The type of test-dose is discussed. Smaller volumes of more concentrated solutions are recommended.