RELATIONSHIP BETWEEN NEEDLE TYPE AND SUBA RACHNOID CATHETER POSITION IN CONTINUOUS SPINAL-ANESTHESIA

The subarachnoid position of the microcatheter has an impact on the ou tcome of continuous spinal anaesthesia (CSA). The present prospective, randomised study investigated the influence of two different spinal n eedles on the radiographically documented subarachnoid positions of mi crocatheters in CSA. In addition, the influence of the subarachnoid po sition of the microcatheter on onset time of analgesia, dose requireme nt of local anaesthetics, and level of analgesia was examined. Methods . Forty orthopaedic patients received CSA using a 28-gauge spinal cath eter inserted either through a non-directional 22-gauge Quincke needle (group 1) or a directional 22-gauge Sprotte needle (group 2). After i nitial injection of 2 ml to a maximum of 5 ml of supplemental doses of 0.5% plain bupivacaine, onset time of analgesia at the level of T 10, dose requirement of bupivacaine, and the achieved analgesic level wer e registered. After surgery, a dye-enhanced AP X-ray film of the lumba r spine was performed for radiological control of the subarachnoid cat heter position. Results. There was a higher number of cranial catheter positions in group 2 (60%) compared with group 1 (40%, P=0.037). In c ontrast to group 1, with 35% caudally directed catheters, no catheter was seen in a caudal position in group 2. Onset time of analgesia (P=0 .0002) and anaesthetic dose requirement (P=0.037) were lower in patien ts with cranially directed catheters compared to patients with the cat heters situated at the level of the puncture site or in a caudal posit ion. Maximal analgesic levels were higher in cranially directed cathet ers compared with other localisations (P=0.022). Conclusions. Sprotte needles provide a higher number of cranially directed microcatheters, which are associated with faster onset of analgesia, lower dose requir ement of local anaesthetics, and higher analgesic levels in CSA. The r esults suggest more effectiveness and probably more safety in microcat heter CSA using Sprotte needles for catheter insertion.