[Does a cone-shaped cannula needle offer an advantage in spinal anesthesia?].

The so-called atraumatic spinal cannula of Sprotte is a modification of the Whitacre spinal needle. It consists of a conical tip with a lateral opening. This cannula (24 G) is said to cause a very low incidence of postspinal headache. In a prospective study, it was compared to a 25 G cannula with a Quincke tip. PATIENTS AND METHOD. The study was carried out on 500 patients who received spinal anesthesia for operations on the lower extremities. The cannulas were randomly assigned to the patients. Puncture characteristics and number of incomplete blocks were evaluated. Postoperatively patients were interviewed on days 1, 3, 5, and 7. Neither the subjects nor the investigator were aware of the type of cannula used. RESULTS. There were no differences with regard to age and sex; 80% of the patients ranged between 15 and 55 years, with a homogeneous spread. Performance of the block was superior with the Sprotte cannula and the incidence of incomplete blocks was lower (1.6% vs 7.8%, P = 0.0011). There was no significant difference with regard to postspinal headache (8.2% vs 7.8%). CONCLUSIONS. The atraumatic cannula had better puncture characteristics, but there was no statistically significant difference with regard to postspinal headaches.