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Biomedical subjects

J T Jacobson

Publications and source records attributed to J T Jacobson.

At least 19 recordsLinked to original sources
PubMed2000

Effect of underlying heart disease on the frequency content of ventricular fibrillation in the dog heart.

Although prior studies have examined the frequency content of local electrogram characteristics during fibrillation, little is know about the effects of underlying heart disease on these parameters. This study was designed to compare the frequency content of local electrograms during VF in canine models of acute ischemia, subacute infarction, and chronic myocardial infarction (MI) to those in control animals to test the hypothesis that underlying heart disease can alter the basic characteristics of VF. VF was induced using burst pacing in three groups of mongrel dogs. Five dogs were evaluated 8 weeks after LAD occlusion MI, five were evaluated 5 days after experimental MI, and 5 had VF induced before (control) and immediately after LAD occlusion (ischemia). During VF, unipolar electrograms were recorded from 112 sites on the anterior LV and electrograms were evaluated 15 and 30 seconds after VF initiation in each group. Electrograms were analyzed by fast Fourier transform. No significant time dependent changes in VF characteristics were noted. The peak frequency was highest in control animals and 8-week MI, intermediate in 5-day MI, and lowest in acute ischemia (P < 0.01 for pairwise comparisons). In contrast, the fractional of energy within a bandwidth of 25% peak amplitude was highest in acute ischemia, (P < 0.001) and similar in the other three groups. Infarction decreased total energy by approximately 50%. In conclusion, the pressure of ischemia or infarction alters the frequency content of VF in a complex fashion. In addition to decreasing the peak frequency, the shape of the power spectral curve is altered in models of structural heart disease. These results suggest that the electrophysiological changes produced by infarction or ischemia alter the structural organization of ventricular fibrillation.

Animals↗
PubMed1998

Distortion-product otoacoustic emissions hearing screening in high-risk newborns.

Universal infant hearing screening has recently been recommended by the National Institutes of Health. Otoacoustic emissions have been proposed as the first-level screening technique. Although transient evoked otoacoustic emissions have shown limited applications, distortion-product otoacoustic emissions hold promise as a screening technique but have not been fully investigated. The purpose of this study was to determine the validity of distortion-product otoacoustic emissions as a hearing screening technique. A total of 208 ears of 104 infants at risk for hearing loss were tested with both automated auditory brain stem response and distortion-product otoacoustic emission screening protocols. Acoustic brain stem response results were used as the standard for normal hearing. Distortion-product otoacoustic emission results were analyzed by means of calculation of the difference between the mean of the response levels and the mean of the noise floor levels from five frequency pairs between 2000 and 4000 Hz. Pass-fail rates for response above noise floor criteria of 5, 10, and 15 dB were examined. The sensitivity of distortion-product otoacoustic emissions was 50%, 67%, and 87%, and the specificity was 94%, 68%, and 38% at the 5, 10, and 15 dB levels, respectively. The pass-fail criterion of distortion-product otoacoustic emissions should be based on instrumentation calibration, infant status, and an acceptable false-positive, false-negative yield. The ability to test rapidly the hearing of all infants with distortion-product otoacoustic emissions points to the feasibility of using this test as a first-stage screen.

Algorithms↗
PubMed1998

Efficacy of vestibular rehabilitation.

The purpose of this study was to determine significant changes in the Dizziness Handicap Inventory (DHI) scores in patients before and within 1 year after a vestibular rehabilitation program. Efficacy of a vestibular rehabilitation program was tested retrospectively in 37 patients by comparison of pretreatment and posttreatment DHI scores. A significant improvement in test scores was found, indicated by the Sign test at the 0.05 level after vestibular rehabilitation. This difference is evident in the total score and in the functional and physical subscore component. Prerehabilitation and postrehabilitation differences among diagnostic categories were analyzed by using the Kruskal-Wallis test. Patients with peripheral lesions demonstrated greater improvement in the emotional component of the DHI as compared with patients with central or mixed lesions. The Wilcoxon two-sample test assessed the influence of compliance with a home exercise program after discharge from a vestibular physical therapy program. There was no significant difference in improvement between patients who performed home exercises for at least a month after discharge and those who did not.

Adult↗
PubMed1998

Teratogenic hearing loss: a clinical perspective.

OBJECTIVE: The Joint Committee on Infant Hearing recently published a series of indicators that place a neonate at risk for hearing loss. Included among these risk factors are environmental teratogens capable of negatively impacting the developing auditory system. This article serves to revisit and update potential environmental teratogens. The characteristic clinical presentation with audiometric, electrophysiologic, and temporal bone findings as well as available treatment options are discussed. DATA SOURCES: A Medline search encompassing the latter half of this century was undertaken to review pertinent literature regarding infectious, chemical, physical, and maternal teratogens and their impact on hearing impairment. CONCLUSIONS: Prevention and early recognition of environmental teratogenic exposure play a critical role in the reduction of childhood hearing loss and deafness. The importance of longitudinal follow-up in these patients is stressed.

Abnormalities, Drug-Induced↗
PubMed1995

Nosology of deafness.

It is estimated that about one half of all congenital deafness and/or hearing impairment is inherited and that approximately one third of this communicative disorder is associated with syndromic abnormalities. The remainder of inherited deafness occurs as an isolated entity, independent of alterations in physical status or any disease process. This latter group typically presents with no clinical signs or symptoms or other dysmorphic stigmata that might help in the early identification of hearing loss. As contemporary advances in genetic testing and therapy emerge, there is an ever-increasing opportunity to provide improved diagnosis and counseling to those with inherited disorders. Over the past 3 decades, there have been several distinct categorical systems introduced to define deafness. Most often, the nosology of deafness is described by either origin, onset, degree and type of severity, and/or structural pathology. Therefore, understanding the cause and nature of hearing loss is the first measure in the accurate diagnosis and management of patient care. This article describes several classification schemata, citing examples of numerous congenital syndromes and other disorders that contribute to deafness.

Chromosome Aberrations↗
PubMed1995

Teratogenic hearing loss.

Congenital hearing loss continues to be a devastating and disabling affliction in our society. In an effort to promote early recognition and treatment of hearing impairment in children, the Joint Committee on Infant Hearing has established a series of risk factors that place a newborn or infant at risk for hearing loss. These factors have been selected based on either genetic evidence of inherited familial hearing loss, acquired hearing loss from either known or unknown causative agents, or multifactorial inheritance that combines genetic and non-genetic factors. Included in these risk factors are exposures to environmental agents that possess the potential to adversely affect the developing auditory system. In this article, the principal environmental teratogens and their potential impact upon the auditory system will be reviewed.

Embryonic and Fetal Development↗
PubMed1995

Treacher Collins syndrome: otologic and auditory management.

Treacher Collins syndrome (TCS) is an autosomal dominant genetic disorder, the phenotypic expression of which is seen in the head and neck area. The syndrome has full penetrance but variable expressivity even among family members, and recent investigation has reported gene site on chromosome 5q. TCS has a reported prevalence of 1 in 50,000 live births with about 40 percent of new occurrences resulting from a positive family history and a 60 percent new mutation rate. The clinical features of TCS involve bilateral abnormalities of the pinnae, external auditory canal, tympanic membrane, and middle ear space. Microtia has been reported to be as high as 85 percent, with one third of patients presenting with stenosis or complete atresia. Treacher Collins patients present with maximum conductive hearing loss often compounded by a high-frequency sensory component. This article describes the otologic and audiologic diagnosis and management of TCS.

Adolescent↗
PubMed1995

Factors impacting the success of computerized preadmission screening.

Many approaches to controlling costs under managed care rely on the ability to prospectively identify the type or level of service a patient requires at the time of presentation. Although computers may effectively predict these factors, the impact of such a computer system is greatly dependent on its integration into the admission process. Three factors that influence the effectiveness of predictive screening using a computer were identified. They are detection, intervention and compliance. The effect of these factors was then measured in a prospective randomized trial evaluating the effectiveness of computerized preadmission screening for predicting the appropriateness of inpatient care. This paper examines the three factors and their impact on the effectiveness of the system. A mathematical model that relates the factors to the overall effectiveness of computerized preadmission screening is proposed and considered in a more general context.

Diagnostic Tests, Routine↗
PubMed1994

The effects of noise in transient EOAE newborn hearing screening.

The use of transient evoked otoacoustic emissions (TEOAEs) has been advocated as the first stage entry level technique for universal newborn hearing screening. To date, the majority of TEOAE infant testing has been conducted under controlled noise conditions; i.e., acoustically treated sound suites. As a result, previously reported TEOAE evaluations may not realistically represent test outcomes in actual hospital screening settings. The purpose of this study was to compare the results of TEOAEs with auditory brainstem response (ABR) hearing screening in a hospital environment where noise conditions do not meet the same ambient noise specifications as those found in sound rooms. A total of 119 stable newborns (67 high risk, 52 normal) ranging in post-conceptual age (PCA) from 33 to 41 weeks received both the ABR and TEOAE screening protocols. Testing was conducted at crib side in either the well baby nursery or the neonatal special care unit (NSCU). Newborn ABR screening failed 8 (3.8%) of 224 ears, whereas TEOAE testing failed 85 (38.4%) and could not test another 22 (9.8%) ears. That is, only 117 (52.2%) of the 224 ears passed the TEOAE test. Using the ABR as the reference test the specificity and sensitivity for TEOAE was 52% and 50%, respectively. Noise levels measured by the probe microphone within the ear canal exceeded those levels (30 dBA SPL) recommended for TEOAE newborn hearing screening. Results of this study suggest that under realistic hearing screening test conditions, TEOAE results may be influenced by the level of noise in the testing environment. Whereas significant advances have been attained in TEOAE measurement during the past decade, clinical evidence supports the need for continued research aimed at solving problems before this technique can be used efficiently for newborn screening.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1993

Surface contour three-dimensional imaging in congenital aural atresia.

Sixty-five patients with congenital aural atresia-stenosis had three-dimensional reconstructions of their high-resolution computed tomographic scans. Surface anatomy of the temporal bone was readily demonstrated, including its relation to the temporomandibular joint. Three important findings were noted. (1) Contrary to popular belief, the condyle of the mandible does not rest against the anterior face of the mastoid bone. (2) A bony cleft or groove is often in the lateral temporal bone through which the facial nerve may exit. (3) Duplications of bony structures attached to or part of the temporal bone are clearly defined. The information gained from the routine use of three-dimensional imaging of the computed tomographic scan alerts us to potential intraoperative problems that may otherwise escape our scrutiny, particularly if only two-dimensional computed tomographic scanning is done.

Ear Canal↗
PubMed1992

Effect of irradiation on guinea pig ABR thresholds.

A significant number of patients undergo irradiation to the temporal bone for malignancies. Conflicting reports exist regarding the effects of irradiation on hearing thresholds. Although radiation-induced otitis media and osteoradionecrosis of the ossicles with resultant conductive hearing loss are well-documented, there is disagreement regarding the effect of irradiation on sensorineural hearing. Previous animal models, relying only on behavioral tests and reflex thresholds, have failed to reveal consistent threshold shifts after irradiation. However, with the advent of auditory brainstem response (ABR) testing, a reliable objective measurement of hearing in animals is available. Hearing thresholds were determined bilaterally by ABR testing in 21 albino guinea pigs. The left temporal bones of sixteen animals were then irradiated with a total dose ranging from 5750 to 7000 cGy over 7 weeks. The right ears of these animals, plus both ears of five nonirradiated guinea pigs, served as controls. Follow-up threshold ABRs were obtained immediately post-irradiation (RT), and at 6 and 12 months post-RT. Average thresholds in all groups increased over time: 60 dB in the control group; 53 dB in the control ears of the irradiated animals; and 46 dB in the irradiated ears. There were no statistically significant increases in ABR thresholds for irradiated ears vs. control ears. At the 6-month followup, hearing was actually better in the irradiated ears than the control ears and this difference between ears was significantly greater than the difference at baseline (p < 0.026). Overall, there was no evidence that irradiation produces changes in ABR thresholds.

Animals↗
PubMed1992

Cogan's syndrome: auditory and medical management.

Cogan's syndrome is a rare autoimmune disease characterized by the presence of interstitial keratitis and audiovestibular symptoms. The audiovestibular symptoms include fluctuating sensory hearing impairment, tinnitus, vertigo, and reduced vestibular response. Immediate diagnosis and medical intervention provides optimum auditory recovery. Frequent audiologic assessments are necessary to monitor the disease activity and to aid in the therapeutic levels of steroidal medications. Amplification is often required on a temporary or permanent basis. Two case studies are presented to illustrate the audiologist's role in the identification and management of patients with Cogan's syndrome.

Adrenal Cortex Hormones↗
PubMed1991

Assessing the effectiveness of a computerized blood order "consultation" system.

To optimize blood ordering and accurately assess transfusion practice, in 1987, an "on line" computerized, knowledge-based, blood order critiquing system was integrated into the HELP Hospital Information System (HIS) at LDS Hospital. Evaluations of the computerized ordering system demonstrated its benefits and limitations on transfusion practice. Based on this experience, a second generation blood ordering system using a consultation mode was developed. A pilot test of this blood order consultant system, using historical data in the HELP system's database, was performed. This pilot test demonstrated that the consultation system provided accurate recommendations for red blood cell (RBC) and platelet orders. Comparing the appropriateness of blood orders with the recommendations made by the director of the blood bank, the orders recommended by the computer "consultant" agreed 95.5% of the time. The computer consultation system also recommended fewer RBC units for transfusion. Preliminary results obtained using the consultant approach suggest that we may be able to simplify blood ordering practice and also reduce the number of units of blood products ordered. Based on these findings we are now preparing to compare the "critiquing" and "consultation" approaches using a clinical trial.

Artificial Intelligence↗
PubMed1990

Computer-critiqued blood ordering using the HELP system.

Recently the medical risk of blood transfusions has emphasized the need to improve the safe use of blood products. For the past 2 1/2 years at LDS Hospital we have used the HELP computer system to assist and critique ordering of blood products "on-line" by physicians and nurses. This report details the computer methods used to order blood products and to critique the appropriateness of those orders. Physicians personally enter the orders for more than 45% of the blood products using computer terminals, whereas 7% are from physician standing orders. Nurses enter the remaining orders from written orders (26%), verbal orders (14%), and phone orders (8%). There were 3396 blood orders for 1043 patients generated by 273 physicians during the fourth quarter of 1989. Each order is justified at the time it is entered by selecting from a menu of physician-approved criteria. The criteria are linked to supportive data in the data base, i.e., laboratory results and clinical data. The computer verified that 82% of these orders met criteria. Quality Assurance nurses verified the remaining 18%. Of these 18% only one in eight required manual chart review. After computer and Quality Assurance review, only eight (0.24%) of the orders were found to be true exceptions to established criteria. Physicians and nurses have accepted the computerized critiquing system. Through use of the computer we provide "on-line" critiquing and improve the use of scarce blood product resources.

Blood Banks↗
PubMed1990

Issues in newborn ABR screening.

The introduction of electrophysiologic measures has provided a renewed interest in the early identification of newborns and infants at risk for hearing loss. To date, 14 states have enacted mandatory legislation for newborn hearing screening, whereas other states have incorporated private and hospital-based programs. Although all state and local programs are inherently different, their common goal is to identify hearing loss as early as possible, and to provide appropriate management strategies in the rehabilitative process. While many technical and recording techniques have been established, there remain several unresolved problems associated with newborn screening programs. The purpose of this article is to bring to the forefront several issues of current concern. Major topic areas include screening versus diagnosis, program design, and stimulus variables. A final recommendation regarding the importance of follow-up services is reiterated.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1990

Follow-up services in newborn hearing screening programs.

Newborn hearing screening programs have gained wide acceptance as a means of identifying infants at risk for hearing loss. For the most part, the auditory brainstem response (ABR) technique has been the measurement tool universally adopted in the evaluation of high-risk infants. Over the years, the ABR has been used successfully with a negligible false-negative rate. Unfortunately, program follow-up services have not received similar attention, and there is a lack in program development. This article describes a series of follow-up measures that include the use of a questionnaire sent to the parents/caregivers of 401 infants who pass either the initial or retest ABR screen. A total of 262 (65%) response questionnaires were returned. The results of the questionnaire and recommendations regarding follow-up services are discussed.

Child Health Services↗