The T/QRS ratio of the electrocardiogram does not reliably reflect well-being in fetal lambs.
OBJECTIVE
Our purpose was to determine the diagnostic power of the T/QRS ratio of the electrocardiogram to predict fetal well-being.


METHODS
In 47 fetal lambs (3 to 5 days after surgery, gestational age 123.5 +/- 3.0 days) asphyxia was induced by restriction of uterine perfusion. Fetuses were either pretreated with an adenosine transport inhibitor (n = 16) or a calcium channel blocker (n = 12) or served as controls (n = 19). Arterial oxygen content > or = 1.5 mmol/L or pH > or = 7.15 were chosen as limits for fetal well-being.


RESULTS
Arterial oxygen content was reduced from 3.3 (+/- 1.0) to 1.3 (+/- 0.5) mmol/L, and pH decreased to 7.03 (+/- 0.10). Mortality was 53%. Both drugs did not affect well-being, survival, or the T/QRS ratio. Maximum T/QRS ratios were reached at the peak of asphyxia. Sensitivity and specificity of the T/QRS ratio were 24.0% and 42.6% to predict hypoxemia and 25.1% and 45.3% to predict acidemia. Pearson correlation coefficients for T/QRS ratio versus oxygen content and pH were 0.169 and 0.192, respectively.


CONCLUSIONS
(1) In fetal lambs the T/QRS ratio failed to predict hypoxemia or acidemia. (2) Fetal survival was not correlated with the height of the T/QRS ratio during or after asphyxia.
Department of Obstetrics and Gynecology, University Hospital, Maastricht, The Netherlands.
H H
HH
de Haan
A C
AC
Ijzermans
J
J
de Haan
T H
TH
Hasaart
D000143:Acids / Q000097:blood; D000818:Animals; D001158:Arteries; D001237:Asphyxia / Q000401:mortality / Q000503:physiopathology; D004562:Electrocardiography; D005318:Fetal Heart / Q000187:drug effects / Q000502:physiology*; D005444:Flunarizine / Q000494:pharmacology; D005544:Forecasting; D006304:Health Status; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000209:etiology; D010100:Oxygen / Q000097:blood; D010879:Piperazines / Q000494:pharmacology; D012680:Sensitivity and Specificity; D012756:Sheep; D016019:Survival Analysis
D000143:Acids; D010879:Piperazines; C072040:draflazine; D005444:Flunarizine; D010100:Oxygen