Methods. The demographic and technical data of all the pediatric caudal blocks (CBs) performed from August 1986 to September 1989 in our teaching hospital were prospectively collected on a computerized protocol. Except for 22 high-risk ex-premature infants, all CBs were performed under halothane or isoflurane anesthesia, after premedication with atropine. Moreover, they were performed using local anesthetic solutions containing 1:200,000 epinephrine. A total of 1100 CBs were performed in children younger than 7 years; 203 patients weighed 5 kg or less; 260, 5.1-10 kg; 300, 10.1-15 kg; and 337, more than 15.1 kg. The CBs were also analyzed according to the anesthesiologist's experience with CB: 184 were performed by anesthesiologists who had performed fewer than 10 CBs (Group A); 210, 10-20 CBs (Group B), and 704, more than 20 CBs (Group C).

Results. We found difficult landmarks in 11.2% of our patients. Moreover, it was significantly more frequent ( p = 0.0004) if the patients weighed less than 10 kg, because of poor anatomy or obesity. There were 76 bloody taps (BTs, 6.9%); although there was a statistically insignificant trend toward a lower incidence of BTs in the 5.1-10-kg group, experience seemed to influence the incidence of BTs, as it decreased from 11.4% in Group A to 8.9% and 5.4% in Groups B and C, respectively ( p < 0.05). There were eight systemic reactions (i.e., brisk onset of tachycardia during or shortly after the CB), which were all short-lived and responded quickly to hyperventilation with oxygen. Two occurred despite repositioning the needle after a previous BT, but six occurred with no previous evidence of blood and were thus called “concealed” BTs. Moreover, all occurred in children weighing 10 kg or less. There was only one dural tap. Only nine CBs (0.81%) failed to provide effective intraoperative anesthesia, and 93% of the patients left the recovery room without having required narcotic or non-narcotic analgesics.

Conclusions. Our results confirm that CB is a reliable technique, easy to perform by beginners. It should be stressed, however, that small infants are at increased risk of concealed BTs.