• Lakshmi Vas, Vinay Kulkarni, Madhusudhan Mali, and Hema Bagry.
• Bai Jerbai Wadia Hospital for Children, Acharya Donde Marg, Parel, Bombay, India. lakshmi1@hotmail.com
• Paediatr Anaesth. 2003 Mar 1; 13 (3): 233-43.

BackgroundThis prospective study aimed to assess the extent of spread of dye in the epidural space and whether it would vary in direct proportion to the volume when injecting two volumes of dye.MethodsTen infants, aged 2-36 days (mean +/- SD, 13.30 +/- 13.68 days) and weighing 1.8-4.5 kg (mean +/- SD, 2.60 +/- 0.97 days), who were undergoing major thoracoabdominal surgery under epidural and general anaesthesia, were studied. At the end of surgery, two volumes of radioopaque dye (omnipaque) 0.5 ml.kg(-1) and 1 ml.kg(-1) were injected into the epidural space at a rate of 1 ml.2 min(-1). The spread was studied by taking X-rays after both injections in the left lateral position.ResultsThere were 10 different patterns of spread in the 10 cases. Uniformly circumferential and cylindrical spread was seen only in one infant. In the others, there were segregated patches of anterior and posterior spread with or without interspersed patches of circumferential spread. There was variation in the extent, location and the density of spread, filling defects and skipped segments with both volumes. Back leak of dye along the needle track was seen in three cases. Statistically, segments were 9.30 +/- 3.68 for 0.5 ml.kg(-1), for 1 ml.kg(-1) 11.50 +/- 3.03, 3.03, S, P=0.014; circumferential spread for 0.5 ml.kg(-1) 2.70 +/- 2.16, for 1 ml.kg(-1) 5.90 +/- 3.14 3.59, P=0.006; anterior spread for 0.5 ml.kg(-1) 3.60 +/- 1.58, for 1 ml kg(-1) 7.90 +/- 2.33 5.88, P=0.001; posterior spread for 0.5 ml.kg(-1) 8.20 +/- 3.71, for 1 ml.kg(-1) 9.80 +/- 3.68 3.54, P=0.006. Doubling of spread with doubling of the volume occurred in only one patient. There was a variable increase in extent or in the density of spread with reduction of skipped segments with the 1 ml.kg-1. The probable reasons for this variable spread and the mechanism of epidural anaesthesia in the presence of such spread are discussed.ConclusionsThere is a difference in quantitative as well as qualitative spread in different patients and in the same patient with different volumes. There were statistically significant increases in the number of segments, circumferential, anterior and posterior locations in the 1.0 ml group. Both extent and density of spread improve with the higher volume but not in direct proportion to volume. 1 ml.kg(-1) has a better quantitative as well as qualitative spread than 0.5 ml and has a better chance of producing adequate anaesthesia.

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