Cardiovascular findings in very low birthweight schoolchildren with and without bronchopulmonary dysplasia

BACKGROUND: With the introduction of new therapies in peri- and neonatology, the clinical picture of bronchopulmonary dysplasia (BPD) seems to alter. The consequences of this "new BPD" are of interest. AIM: To evaluate cardiovascular findings during the surfactant era in very low birthweight (VLBW, birth weight < 1500 g) schoolchildren with and without BPD. METHODS: At 7-8 years of age, 34 VLBW children with BPD born in one hospital underwent blood pressure (BP) measurement, electrocardiography (ECG), two-dimensional Doppler and M-mode echocardiography, flow-volume spirometry and whole-body plethysmography. The age- and sex-matched control groups comprised 34 VLBW children without BPD (no-BPD group) and 34 term children (term group). RESULTS: The mean(SD) diastolic BP was significantly higher in the no-BPD than in the BPD group (65(9) vs. 59(8) mm Hg, p < 0.05). No clinically significant tricuspid regurgitations were found. The groups did not differ with respect to right ventricular systolic time intervals corrected for heart rate. The results of all M-mode measurements were within normal range. Compared to term controls, the BPD cases had lower mean(SD) forced expiratory flow in 1 s (90(14)% vs. 99(11)% of ref., p < 0.05) and more often high ratio of residual volume to total lung capacity (15(52%) vs. 4(13%), p < 0.01). No clinically significant correlations were found between current lung function and echocardiographic findings. CONCLUSION: In the surfactant era, school-aged VLBW survivors with and without BPD do not seem to evince indirect signs of elevated pulmonary pressure. The increased pulmonary vascular resistance associated with BPD appears to resolve with time more rapidly than abnormalities in respiratory function.     

Heart rate variability during REM and non-REM sleep in preterm neonates with and without abnormal cardiorespiratory events

Aim

Analyse heart rate variability (HRV) of preterm neonates undergoing a polysomnography in relation to the occurrence of abnormal cardiorespiratory events on one hand and the type of sleep states on the other hand.

Methods

To quantify nonlinear HRV, the numerical noise titration technique is used, adapted to neonatal heart rate data. HRV is calculated for 30 preterm neonates with mean post-conceptional age of 36.4 weeks, divided into three groups according to the occurrence of abnormal events during the polysomnographies and the eventual home monitoring.

Results

Periods of non-REM sleep have lower noise limit values and can be distinguished significantly from periods of REM sleep and from the total recording period. The presence of abnormal events does not influence this finding. Significant differences between groups are only found during non-REM segments by means of the noise limit value computed via numerical noise titration while the linear HRV parameters were not able to discriminate.

Conclusion

ECG measurement of a relatively short non-REM sleep period without specific abnormal events is sufficient to define a mature cardiorespiratory pattern in preterm infants.