The performance of Bispectral Index in children during equi-MAC halothane vs. sevoflurane anaesthesia.

BACKGROUND AND OBJECTIVE: The reliability of the Bispectral Index for evaluating and monitoring the depth of general anaesthesia in children is not as great as for that in adults. Therefore we analysed Bispectral Index performance in children by comparing changes in Bispectral Index values during a standardized and equipotent anaesthetic regimen using either halothane or sevoflurane for the induction and maintenance of general anaesthesia. Special interest was focussed on excitation during induction, and whether it was associated with simultaneous changes in Bispectral Index scores. METHODS: Twenty children (3-15 yr, ASA I-II) scheduled for general surgery were randomly allocated to either halothane (10 patients) or sevoflurane group (10 patients). Anaesthesia was induced by 3% halothane or 7% sevoflurane, either agent administered with 50% N2O in oxygen for 5 min, the period from the beginning of induction until intubation. Thereafter, anaesthesia was maintained by the respective volatile agent at 1 MAC (minimum alveolar concentration; in addition to 70% N2O in oxygen) and supplemented with remifentanil infusion adjusted to maintain the heart rate and mean arterial pressure to within 20% of the baseline values. Excitation at induction was defined as involuntary muscular movements. RESULTS: Sevoflurane induction produced a more rapid depression in Bispectral Index than halothane, the mean difference being greatest (47 Bispectral Index score) at 105 s. Excitation occurred in three patients during sevoflurane induction, which coincided with increases in Bispectral Index values in two of the three patients. During the maintenance phase at 1 MAC, the Bispectral Index (mean +/- SD) was 57+/-7 for halothane and 47+/-9 for sevoflurane (P < 0.05). The remifentanil doses did not differ between both groups. CONCLUSION: In children, halothane anaesthesia was associated with higher Bispectral Index values than sevoflurane when administered at 1 MAC. Large individual variation in Bispectral Index occurred within both groups. Due to these limitations, one should be cautious when interpreting paediatric Bispectral Index data.

High-resolution linkage-disequilibrium mapping of the cartilage-hair hypoplasia gene.

We recently assigned the gene for an autosomal recessive skeletal dysplasia, cartilage-hair hypoplasia (CHH), to 9p21-p13 in Finnish and Amish families. An association was observed between CHH and alleles at D9S163 in both family series, suggesting that these loci are in linkage disequilibrium and close to each other. Here we extended these studies by exploiting the linkage-disequilibrium information that can be obtained from families with a single affected child, and we studied 66 Finnish CHH families with seven microsatellite markers. The analysis based on the Luria and Delbrück (1943) method and adapted to the study of human founder populations suggests that the distance between CHH and D9S163 is approximately 0.3 cM. An eight-point linkage analysis modified to take advantage of all possible information in 15 Finnish and 17 Amish families was capable of narrowing the likely location of CHH to within an interval of 1.7 cM on a male map. The peak lod score of 54.92 was attained 0.03 and 0.1 cM proximal to D9S163 on the male and female maps, respectively. These results confirm the power of genetic resolution, that lies in the study of linkage disequilibrium in well-defined founder populations with one major ancestral disease mutation.