Noise levels in neonatal intensive care unit and use of sound absorbing panel in the isolette.

OBJECTIVE: The purposes of this study were to measure the noise level of a busy neonatal intensive care unit (NICU) and to determine the effect of sound absorbing panel (SAP) on the level of noise inside the isolette. METHODS: The sound pressure levels (SPL) of background noise, baby crying, alarms and closing of isolette's door/portholes were measured by a 2235-Brüel&Kjaer Sound Level Meter. Readings were repeated after applying SAP (3D pyramidal shaped open cell polyurethane foam) to the three lateral walls and ceiling of the isolette. RESULTS: The median SPL of background noise inside the NICU was 56dBA and it decreased to 47dBA inside the isolette. The median SPL of monitor alarms and baby crying inside the isolette were not different than SPL measured under radiant warmer (p>0.05). With SAP, the median SPL of temperature alarm inside the isolette decreased significantly from 82 to 72dBA, monitor alarm from 64 to 56dBA, porthole closing from 81 to 74dBA, and isolette door closing from 80 to 68dBA (p<0.01). There was a significant reduction in the noise produced by baby crying when SAP was used in the isolette (79dBA vs 69dBA, respectively) (p<0.0001). There was also significant attenuation effect of panel on the environmental noise. CONCLUSIONS: The noise level in our NICU is significantly above the universally recommended levels. Being inside the isolette protects infants from noise sources produced outside the isolette. However, very high noises are produced inside the isolette as well. Sound absorbing panel can be a simple solution and it attenuated the noise levels inside the isolette.

Brainstem auditory evoked potentials and middle latency auditory evoked potentials in patients with impaired glucose tolerance.

AIMS: The aim was to investigate the effects of impaired glucose tolerance (IGT) on the central nervous system via brainstem auditory evoked potentials (BAEPs) and middle latency auditory evoked potentials (MLAEPs), and on the peripheral nervous system via nerve conduction studies (NCS). METHODS: Thirty patients with IGT and 20 control subjects underwent NCS, BAEPs and MLAEPs. RESULTS: Tibial distal motor latencies were significantly prolonged in the IGT group; no differences in other parameters, including BAEPs and MLAEPs, were observed between the IGT and control subjects. CONCLUSION: Brainstem involvement may not be seen in IGT patients as in DM. The was no obvious electrophysiological finding indicating peripheral nervous system disfunction in our patients.

500Hz logon versus click ABR maturation.

OBJECTIVES: To provide age-equivalent norms for a 500Hz logon evoked ABR obtained in a group of children ranging 40 weeks-4 years old and compare these 500Hz tonal norms to age-equivalent norms for click-evoked ABR. METHODS: Seventy-seven infants and children ranging from conceptional age of 40 weeks (term babies) to 4 years were tested with both click and tonal ABR without any risk factors for hearing loss. RESULTS: Data analyses were consisted of 6 age groups. Mean wave V latencies were compared with the adult norms. Latencies were decreased by age in both click and tonal ABR recordings. CONCLUSION: Five hundred Hertz of tonal ABR wave V latency did not mature until to 2-4 years old but, click ABR wave V latency reached maturity at the same age range.

Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system.

One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement procedure. Recordings were obtained in 96% of these subjects with this standardised procedure. The group results are presented in terms of peak amplitude and latency, slope of the amplitude growth function and ECAP threshold. The effects of aetiological factors and the duration of deafness on the ECAP were also studied. While large intersubject variability and intrasubject variability (across electrodes) were found, results fell within a consistent pattern and a normative range of peak amplitudes and latencies was established. The aetiological factors had little effect on the ECAP characteristics. However, age affected ECAP amplitude and slope of the amplitude growth function significantly; i.e., the amplitude is higher in the lowest age category (15-30 years). Principal component analysis of the ECAP thresholds shows that the thresholds across 5 electrodes can be described by two factors accounting for 92% of the total variance. The two factors represent the overall level of the threshold profiles ('shift') and their slopes across the electrode array ('tilt'). Correlation between these two factors and the same factors describing the T- and C-levels appeared to be moderate, in the range of 0.5-0.6.

Prognostic value of auditory brainstem response for neurologic outcome in patients with neonatal indirect hyperbilirubinemia.

To investigate the value of the auditory brainstem response as a reliable test for the neurologic prognosis of infants with neonatal indirect hyperbilirubinemia, auditory brainstem response studies were performed in 22 infants. The patients were followed up until 12 months of age. Two patients demonstrated pathologic auditory brainstem response consistent with auditory neuropathy but had no neurologic finding except a lack of speech at 12 months of age. Two other patients had neurologic sequelae, one showing severe dyskinetic cerebral palsy, the other mild hypotonia and motor retardation, but their auditory brainstem response results were normal. These results suggested that auditory brainstem response examination might not provide reliable information for the neurologic prognosis. Neurologic disturbances resulting from bilirubin neurotoxicity can be seen in patients with a normal auditory brainstem response, but patients with an abnormal auditory brainstem response may not have any neurologic dysfunction apart from speech retardation.

Effects of topical otic preparations on hearing in chronic otitis media.

Most of the topical otic preparations have been shown to cause ototoxicity. In this study ciprofloxacin hydrochloride, a relatively new topical agent, and gentamicin sulfate were studied in two groups of 20 patients with chronic otitis media. Patients were randomly selected to receive either ciprofloxacin (200 microg/ml) or gentamicin sulfate (5 mg/ml) locally, five drops three times a day for 10 days. Clinical response was seen in 20 of 20 patients in the ciprofloxacin group compared with 6 of 20 patients in the gentamicin group. Audiometric evaluation revealed no significant ototoxic effect in either group. In fact, hearing thresholds were slightly better than pretreatment levels in both groups.