RESUMO
Objective. To devise some indicators for measuring and evaluating the neonatal cardiac reserve by using phonocardiogram test (PCGT). Methods. Two hundred and thirty one (231) full term and one hundred and fifty four (154) preterm infants participated in this study. The amplitude ratio of the first heart sound to the second heart sound (S1/S2), the ratio of diastolic to systolic duration (D/S) and the cardiac contractility change trend after stimulation (CCCTS) of the neonates were measured, calculated and analyzed. Results. The S1/S2, D/S and CCCTS of full preterm infants were higher than that of preterm infants. The differences of D/S and CCCTS between them were significant (P<0.05). According to the full term neonatal cardiac reserve data, a normal reference range of full term neonatal cardiac reserve was primarily known. Conclusions. The indicators S1/S2, D/S and CCCTS may be beneficial for evaluating the neonatal cardiac reserve. We can screen out neonates with reduced cardiac reserve by using the phonocardiogram test.