Haemodinamic instability is frequently observed in children submitted to CPB and is related to CPB duration, reduction of vascular tonus, hypothernua degree, water restriction and myocardial hypofunction. The aim of this study is to observe if endocrine adaptation could promote, to maintain or to increase the shock presented during CPB reperfusion. We studied 37 pat. CA(1-10 years). divided in 3 groups according the necessity of CPB and esophageal temperature during surgical procedure (hypothernua = temp. < 30°C). Blood samples were obtained on basal condition, anesthetic induction, opening thorax, each 30 min. during CPB and 24 h after the end of surgery. The results are showed on table and expressed as mean (SD).

Table 1

Mainly hormonal changes (specially in group 1) are: reduction on cortisol. T4. TSH and elevation on ACTH. glucose and insulin concentrations T4 and TSH remained low 24h after surgery. Statistical analysis of each hormone at different time but in the same group (Wilcoxon rank test) identified significant alterations both in groups 1 and 3, during CPB Comparison of results from different groups, but in the same time (Mann-Whitney sum test) detected significant changes on T4 (30° of CPB) between the groups 1 and 2, and on TSH (30° of CPB) between the groups 2 and 3.

We concluded that (i) the group submitted to CPB+hypothermia presented the most severe alterations (ii) glucose elevation occur in spite of insulin increase, suggesting peripheral resistance and sub-optimal insulin secretion Hypocortisolemia and hypothyroxinemia could be one of the factors inducing or worsening the haemodinamic instability during CPB-reperfusion, because of their capacity to modulate the adrenergic receptor sensitivity.