Caudal analgesia in children. Influence on ventilatory efficiency during halothane anaesthesia.

The influence of caudal analgesia on pulmonary ventilation and gas exchange was studied in 26 children during halothane anaesthesia with spontaneous breathing. Two groups of children were studied with 13 patients in each group. One group received caudal analgesia. The other group had no caudal blocks. All children were subjected to lower abdominal and genital surgical procedures. Minute ventilation and respiratory rates were significantly lower in the caudal group than in the non-caudal group. Wastea minute ventilation and VD/VT ratios were increased in the non-caudal group. The end tidal carbon dioxide concentration was unchanged in both groups. The lower minute ventilation in the caudal group eliminated the same amount or even greater amounts of CO2 per minute indicating an improved gas distribution at slow respiratory rates. The improved ventilation efficiency and the excellent immediate postoperative pain relief achieved by caudal analgesia justifies its frequent use for these operative surgical procedures.