An incidence of sensorineural hearing loss (SNHL) in infants surviving PPHN as high as 53% has been reported (Pediatrics. 81(5):650-6, 1988). However, one study reported an incidence as low as 0% in infants with similar echocardiographic and/or catheterization criteria (Pediatrics. 90(3):392-6, 1992). This latter study differs from all previous reports in that none of the infants were hyperventilated. Other confounders in these studies include dysmaturity, infection and the use of ototoxic drugs. In addition, PPHN has a variety of etiologies and no single method of management. Since there may be site-specific differences not only in management, but in the incidence of hearing loss, we looked at our own institution's experience.

All charts of newborns admitted from 1990 through 1994, with a diagnosis of PPHN, were pulled for review. Of 200 charts, only those infants greater than 35 weeks gestation, and having echocardiographic and/or catheterization evidence of PPHN were included. The presence of SNHL was identified by an abnormal brainstem auditory evoked response (BAER), which included both clicks and bursts at 1000-4000 Hz to assess cochlear threshold, intensity latency curves, and absolute latency and interpeak intervals of waves I, III, IV.

A total of 65 newborns with PPHN were identified. BAERs were performed on 35 on these infants and were normal in 34 (97%). Approximately half of the infants with PPHN (33) and half of the infants with PPHN who received BAERs(17) had been hyperventilated (PaCO2 < 25 torr and pH > 7.55). The one infant with an abnormal BAER was hyperventilated, with the lowest PaCO2=22 torr and highest pH=7.68.

Thus, we found a much lower incidence of SNHL in term infants with PPHN than in previous reports, despite the fact that hyperventilation was used commonly. This suggests that neither hyperventilation nor PPHN per se increase the risk for SNHL.