The incidence of postdural puncture headache (PDPH) was investigated prospectively in 873 consecutive patients undergoing a total of 1021 spinal anesthesias, and its association to age, sex, needle size, number of attempted dural punctures, needle bevel direction, duration of postoperative recumbency, and previous PDPH was analyzed. Multivariate analysis showed that age (P less than 0.0001), direction of the bevel of the needle when puncturing the dura mater (P = 0.022), and a history of previous PDPH (P = 0.018) were significant predictors of PDPH. The estimated relation between PDPH, on the one hand, and age and orientation of the bevel, on the other, enables the anesthetist to predict the risk of PDPH and thereby to choose an acceptable age limit for spinal anesthesia.

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A new method for monitoring neuromuscular function based on measurement of acceleration is presented. The rationale behind the method is Newton's second law, stating that the acceleration is directly proportional to the force. For measurement of acceleration, a piezo-electric ceramic wafer was used. When this piezo electrode was fixed to the thumb, an electrical signal proportional to the acceleration was produced whenever the thumb moved in response to nerve stimulation. The electrical signal was registered and analysed in a Myograph 2000 neuromuscular transmission monitor. In 35 patients anaesthetized with halothane, train-of-four ratios measured with the accelerometer (ACT-TOF) were compared with simultaneous mechanical train-of-four ratios (FDT-TOF). Control ACT-TOF ratios were significantly higher than control FDT-TOF ratios: 116 +/- 12 and 98 +/- 4 (mean +/- s.d.), respectively. In five patients not given any relaxant during the anaesthetic procedure (20-60 min), both responses were remarkably constant. In 30 patients given vecuronium, a close linear relationship was found during recovery between ACT-TOF and FDT-TOF ratios. It is concluded that the method fulfils the basic requirements for a simple and reliable clinical monitoring tool.