Abnormal heart rate variability at school age in survivors of neonatal hypoxic-ischemic encephalopathy managed with therapeutic hypothermia.

BACKGROUND AND OBJECTIVE: Major deficits in the autonomic nervous system function, detected by measuring heart rate variability (HRV), are reported in neonatal hypoxic-ischemic encephalopathy (HIE)). However, it is unknown if they will recover in the long-term. Because of the possible implications for the neurological outcome, this study aimed to evaluate the HRV at school age, in a cohort of children who survived HIE managed with therapeutic hypothermia. METHODS: A cross-sectional study of HRV in 40 children: 20 HIE survivors and 20 healthy peers. All underwent 5-min plethysmography using the PPG Stress Flow device (BioTekna Italy). Absolute and normalized HRV spectral power in the very low frequency (VLF), low frequency (LF), and high frequency (HF) bands and total power were compared between patients and healthy children. The outcome evaluation included neurological, cognitive (WISC-IV), and psychosocial (Parent Stress Index-Short Form-PSI-SF and psychosocial interview) measures. RESULTS: All mean HRV values were significantly higher in survivors of HIE, compared to healthy peers, with the larger effect size for the HF band (Total Power 8.57 ± 0.59 vs 7.82 ± 0.77 ms2, p .003 ES 0.21; HF 7.82 + 0.77 vs 8.57 + 0.59 ms2, p .001 EF 0.24). None of the children had major health, neurological and psychosocial (PSI-SF/interview) problems. The IQ (WISC-IV) was normal in 17/20 patients, borderline in 2, and <70 in 1. CONCLUSIONS: HRV measures highlight autonomic dysfunction at school age in survivors of neonatal HIE, in the absence of major neurodevelopmental and psychosocial problems. The significance of this finding for children's future life needs further neuropsychiatric investigations and longer follow-up.

Hyperventilation and seizures in an adolescent female.

A 16 year-old girl was admitted after suffering from recurrent episodes of dyspnea and stridor, cyanosis, loss of contact, stiffening of all four limbs, clenching of the jaw and eye retroversion that lasted for a few seconds to a minute, followed by slow recovery of consciousness without any loss of sphincter control. These symptoms began at the age of 11 and worsened over time. Prolonged rate corrected QT intervals was observed with an ECG. Two cardio-respiratory monitorings were performed (one during daytime hours while the patient was awake, and one at night time while the patient slept). Daytime recordings showed 17 central apnoeas and 97 central hypopneas, with an apnea-hypopnea index (AHI) of 13.2 events/hour, that were associated with severe oxyhemoglobin desaturation. In contrast, night time recordings were normal (AHI=1.1 events/hour). The patient underwent diurnal monitoring of transcutaneous pCO2(PtcCO2), transcutaneous O2(PtcO2), SpO2 and end tidal CO2 (PETCO2), with simultaneous monitoring of regional cerebral oxymetry (rSO2) which showed values of PtcCO2 between 8 and 15 mmHg, suggesting several episodes of marked hyperventilation. Twenty-nine episodes of severe arterial desaturation (SpO2<50%) were registered, all after the same number of apnea events, with ascent of PtcO2 up to 28 mmHg at the end of apnea. During the final phase of apnea, the patient showed cyanosis, contact disturbance, grimaces, oral movements of rhyme, and, on three occasions, partial seizures. A mask was packaged and applied daytime to the face of the patient during episodes of hyperventilation to prevent, together with a psychiatric follow up, rapid falls of PaCO2 levels determining central apnoeas.