Very low-birth weight infants with patent ductus arteriosus (PDA) accompanied by severe heart failure do not respond to indomethacine therapy. It is essential to stabilize the general condition of these infants until surgical intervention. We tried to regulate the pulmonary blood flow to control congestive heart failure by administering supplemental nitrogen inhalation therapy to six very low-birth-weight infants with PDA. After the inhalation of supplemental nitrogen gas was begun, the arterial oxygen saturation and partial oxygen pressure immediately decreased. Furthermore, the blood pH, systolic pressure, and urine output significantly increased. The infants were well stabilized. Furthermore, there were no complications related to nitrogen gas inhalation. Supplemental nitrogen inhalation therapy is an effective and feasible therapy for severe congestive heart failure in very low-birth-weight infants with PDA.

Ductus Arteriosus, Patent↗

PubMedDate not supplied

Effect of additional intraaortic balloon support during weaning from a left ventricular assist system.

A safe and reliable method of weaning from a left ventricular assist system (LVAS) is necessary for successful circulatory support in patients with marginal heart failure. The purpose of this study is to assess the effect of additional intraaortic balloon (IAB) support during weaning from an LVAS by means of the LV pressure-volume relationship. A pneumatic LVAS with a sac-type blood pump was implanted in six adult mongrel dogs weighing 14 to 20 kg. All dogs had a drainage cannula placed in the left atrium and an outflow conduit in the ascending aorta. Hemodynamic parameters, pulmonary arterial flow, and pump output were monitored. An IAB was inserted through the groin. A conductance catheter and microtip manometer were inserted into the LV cavity. As a combination driving mode, LVAS ejection in the early diastolic phase and IAB inflation in the late diastolic phase were applied. After evaluation of baseline LV function, the pressure-volume relationship was repeatedly measured during change of driving modes as isolated LVAS, LVAS + IAB (1:1), LVAS + IAB (2:1), and isolated IAB supports. Finally, LV failure was introduced by stepwise ligation of left coronary arteries, and the LV pressure-volume relationship was measured in each driving mode. Under normal conditions, the pressure-volume loop showed no significant change among the four driving modes. In contrast, the LV pressure-volume relationship significantly improved according to the degree of additional IAB support on LVAS assistance under the condition of LV failure. These results suggest that additional IAB support might improve LV energy during weaning from an LVAS.

Animals↗

PubMedDate not supplied

Evaluation of middle-ear implant: a six-month observation in cats.

The efficacy of a middle-ear implant was evaluated by measuring auditory brain stem responses. Middle-ear implants, including an input-transducer, an amplifier, a battery and an output-transducer, were implanted in cats. Most of the implants were kept functioning for a six-month period. Observation on the characteristics of these implants during this time showed allowable changes in an implant, now being prepared, for use in human subjects.

Animals↗

PubMedDate not supplied

Middle ear implant for humans.

In humans, a partially implantable middle ear implant (MEI) will first be applied, followed by a wholly implantable MEI, since with the former only an induction coil and a vibrator (to the stapes' head) are used. One of the various advantages of the partially implantable MEI vis-à-vis air conduction hearing aids is that the tone quality is of much higher fidelity, with less noise.

Cochlear Implants↗

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Stimulated otoacoustic emissions in children with sensorineural hearing loss.

Our previous studies of stimulated oto-acoustic emissions (OAEs) have revealed that the OAE threshold indicates the grade of inner ear impairment. The present study is a survey of OAE in children of school age. The mean OAE threshold values of 113 ears with normal hearing and 45 ears with functional deafness were 5.9 dB nHL and 6.2 dB nHL, respectively. In sensorineural loss the value was noted to increase according to its grade, classified into four groups, measuring 37.2 dB nHL in the group with severe loss higher than 91 dB. The findings suggest that the OAE threshold is useful for an indicator of inner ear function in children. There still remains the problem to be solved by a contrivance of noise removal for application of OAE to hearing tests in children of pre-school age.

Adolescent↗

PubMedDate not supplied

The auditory stimuli to evoke a clear average response at behavioral threshold.

Explore the source record for details and available documents.

Acoustic Stimulation↗

PubMedDate not supplied

Brain stem response audiometry at speech frequencies.

Auditory-evoked brain stem response (BSR; wave V) was studied, using tone pips at three speech frequencies (500, 1 000 and 2 000 Hz) as stimuli. The tone pips consisted of 5-ms rise-decay times without a plateau. BSR recordings were made in 10 normal subjects and in 16 subjects with impaired hearing. In the normal subjects, BSR thresholds ranged from 10 to 20 dB SL at these three frequencies. In the subjects with impaired hearing, BSR thresholds corresponded well to conventional pure-tone thresholds at each frequency in cases of low- as well as high-frequency hearing loss. In all subjects with impaired hearing, the BSR thresholds were higher by as much as 25 dB than the pure-tone thresholds. The mean differences between these two thresholds at 500, 1 000 and 2 000 Hz were 11.3 +/- 8.0, 10.9 +/- 6.2 and 10.9 +/- 7.3 dB, respectively. Thus, we conclude that the BSR is useful for objective assessment of hearing thresholds at each of these speech frequencies.

Acoustic Stimulation↗

PubMedDate not supplied

Cochlear initiation site of the frequency-following response: a study of patients with sensorineural hearing loss.

The cochlear initiation of the frequency-following response (FFR) was assessed by comparing the FFR thresholds to the pure-tone thresholds in four groups of patients suffering from different forms of sensorineural hearing loss. The groups consisted of patients suffering from (1) pure high-frequency hearing losses; (2) high-frequency hearing losses mixed with moderate low-frequency losses; (3) flat hearing losses, and (4)low-frequency hearing losses. Across groups, the pattern of thresholds of the FFR evoked by 500-Hz tome bursts paralleled the pattern of pure-tone thresholds only for the low frequencies- not the high frequencies. In order to clarify the interpretation of this result, a high-pass masking experiment was performed on patients with low-frequency hearing losses. High-pass masking noise did not affect the FFR thresholds to 500-Hz tone burst, but it produced a phase shift of the FFR at stronger intensity levels. The data are interpreted as strongly supporting the view that the FFR at low levels is initiated primarily by activity in the apical portion of the cochlea.

Acoustic Stimulation↗

PubMedDate not supplied

Effects of number and interstimulus interval of tone pips on fast responses.

Effects of stimulus number and interstimulus interval on auditory-evoked fast responses (BSR: Jewett's V, and middle-latency components: Na, Pa and Nb) were studied by using 1000- and 500-Hz tone pips in 6 normal human adults. At a stimulus intensity of 50 dB SL, 500 stimuli evoked BSRs and the middle-latency components in all cases. At a stimulus intensity of 30 dB SL, 1000 stimuli were necessary to evoke BSRs and Na in all 6 subjects. Even 4000 stimuli were not sufficient for identifying Pa in 1 subject and Nb in 3 subjects. The largest mean peak-to-peak amplitude was the Na-Pa amplitude, but, differences across subjects were large. On the other hand, the BSR-Na amplitude showed relatively small differences across subjects. The BSR latencies were highly stable across subjects. These characteristics indicate that the BSR-Na component is more suitable as an indicator for objective audiometry than either the Na-Pa or Pa-Nb component. The BSR-Na amplitude did not show a decrease as the interstimulus interval was decreased from 104 to 32 ms. On the other hand, the Na-Pa amplitude significantly decreased as the interstimulus interval was decreased from 104 to 42 ms, and the Pa-Nb amplitude also significantly decreased as the interstimulus interval was decreased from 104 to 73 ms. Therefore, because of its resistance to the effects of high rates of stimulation, the BSR-Na component appears to be a suitable audiometric index in the clinical situation where time constraints are a consideration.

Acoustic Stimulation↗

PubMedDate not supplied

Successful resection of cardiac fibroma with ventricular tachycardia.

A 22-year-old male was admitted to Niigata University Hospital complaining of palpitation. Echocardiogram, cineangiogram, and Holter electrocardiogram revealed a cardiac fibroma complicated by ventricular tachycardia (VT). The tumor extended from the interventricular septum to the anterior surface of the left ventricle, and an electrophysiological study demonstrated that the focus of the VT was situated at the tumor. The tumor was excised successfully. The patient is doing well two years after operation without any antiarrhythmic drugs, and VT has not recurred.

Adult↗