Ja. Short et al., Arterial to end-tidal carbon dioxide tension difference in children with congenital heart disease, BR J ANAEST, 86(3), 2001, pp. 349-353
Citations number
6
Categorie Soggetti
Aneshtesia & Intensive Care","Medical Research Diagnosis & Treatment
In children with congenital cyanotic heart disease, right-to-left intracard
iac shunting causes an obligatory difference between arterial and end-tidal
carbon dioxide tension (Pa-CO2-PE'(CO2)) as venous blood, rich in carbon d
ioxide, is added to the arterial circulation. This obligatory Pa-CO2-PE'(CO
2) difference, which can be predicted from knowledge of oxygen saturation,
haemoglobin concentration and Pa-CO2, increases as oxygen saturation decrea
ses. most markedly when the haemoglobin concentration is high. A second pos
sible cause of the Pa-CO2-PE'(CO2) difference is the effect of pulmonary hy
poperfusion caused by the shunt. We studied 60 children undergoing cardiac
surgery and compared the predicted the PaCO2PE'(CO2) difference with measur
ed values to investigate the extent to which additional factors influence t
he clinically observed Pa-CO2-PECO2. In many children, observed values were
much greater than predicted, which is compatible with some degree of pulmo
nary hypoperfusion. However, this was not felt to represent the complete pi
cture in all patients. Another cause of ventilation-perfusion mismatch was
suspected in those children who showed a considerable improvement in oxygen
saturation during ventilation with an increased FIO2. We believe that pulm
onary congestion caused by large left-to-right shunts may further increase
the Pa-CO2-PECO2 difference.