Reducing Care Overuse in Older Patients Using Professional Norms and Accountability : A Cluster Randomized Controlled Trial

BACKGROUND

Effective strategies are needed to curtail overuse that may lead to harm.

OBJECTIVE

To evaluate the effects of clinician decision support redirecting attention to harms and engaging social and reputational concerns on overuse in older primary care patients.

DESIGN

18-month, single-blind, pragmatic, cluster randomized trial, constrained randomization. (ClinicalTrials.gov: NCT04289753).

SETTING

60 primary care internal medicine, family medicine and geriatrics practices within a health system from 1 September 2020 to 28 February 2022.

PARTICIPANTS

371 primary care clinicians and their older adult patients from participating practices.

INTERVENTION

Behavioral science-informed, point-of-care, clinical decision support tools plus brief case-based education addressing the 3 primary clinical outcomes (187 clinicians from 30 clinics) were compared with brief case-based education alone (187 clinicians from 30 clinics). Decision support was designed to increase salience of potential harms, convey social norms, and promote accountability.

MEASUREMENTS

Prostate-specific antigen (PSA) testing in men aged 76 years and older without previous prostate cancer, urine testing for nonspecific reasons in women aged 65 years and older, and overtreatment of diabetes with hypoglycemic agents in patients aged 75 years and older and hemoglobin A1c (HbA1c) less than 7%.

RESULTS

At randomization, mean clinic annual PSA testing, unspecified urine testing, and diabetes overtreatment rates were 24.9, 23.9, and 16.8 per 100 patients, respectively. After 18 months of intervention, the intervention group had lower adjusted difference-in-differences in annual rates of PSA testing (-8.7 [95% CI, -10.2 to -7.1]), unspecified urine testing (-5.5 [CI, -7.0 to -3.6]), and diabetes overtreatment (-1.4 [CI, -2.9 to -0.03]) compared with education only. Safety measures did not show increased emergency care related to urinary tract infections or hyperglycemia. An HbA1c greater than 9.0% was more common with the intervention among previously overtreated diabetes patients (adjusted difference-in-differences, 0.47 per 100 patients [95% CI, 0.04 to 1.20]).

LIMITATION

A single health system limits generalizability; electronic health data limit ability to differentiate between overtesting and underdocumentation.

CONCLUSION

Decision support designed to increase clinicians' attention to possible harms, social norms, and reputational concerns reduced unspecified testing compared with offering traditional case-based education alone. Small decreases in diabetes overtreatment may also result in higher rates of uncontrolled diabetes.

PRIMARY FUNDING SOURCE

National Institute on Aging.

Seamless Integration of Computer-Adaptive Patient Reported Outcomes into an Electronic Health Record

BACKGROUND

Patient-reported outcome (PRO) measures have become an essential component of quality measurement, quality improvement, and capturing the voice of the patient in clinical care. In 2004, the National Institutes of Health endorsed the importance of PROs by initiating the Patient-Reported Outcomes Measurement Information System (PROMIS), which leverages computer-adaptive tests (CATs) to reduce patient burden while maintaining measurement precision. Historically, PROMIS CATs have been used in a large number of research studies outside the electronic health record (EHR), but growing demand for clinical use of PROs requires creative information technology solutions for integration into the EHR.

OBJECTIVES

This paper describes the introduction of PROMIS CATs into the Epic Systems EHR at a large academic medical center using a tight integration; we describe the process of creating a secure, automatic connection between the application programming interface (API) which scores and selects CAT items and Epic.

METHODS

The overarching strategy was to make CATs appear indistinguishable from conventional measures to clinical users, patients, and the EHR software itself. We implemented CATs in Epic without compromising patient data security by creating custom middleware software within the organization's existing middleware framework. This software communicated between the Assessment Center API for item selection and scoring and Epic for item presentation and results. The middleware software seamlessly administered CATs alongside fixed-length, conventional PROs while maintaining the display characteristics and functions of other Epic measures, including automatic display of PROMIS scores in the patient's chart. Pilot implementation revealed differing workflows for clinicians using the software.

RESULTS

The middleware software was adopted in 27 clinics across the hospital system. In the first 2 years of hospital-wide implementation, 793 providers collected 70,446 PROs from patients using this system.

CONCLUSION

This project demonstrated the importance of regular communication across interdisciplinary teams in the design and development of clinical software. It also demonstrated that implementation relies on buy-in from clinical partners as they integrate new tools into their existing clinical workflow.

Integration of Continuous Glucose Monitoring Data into an Electronic Health Record System: Single-Center Implementation

Managing data from continuous glucose monitoring (CGM) systems presents challenges to health care provider teams that rely on the electronic health record (EHR) during patient visits. A method of integrating CGM data with the EHR that relies on the Dexcom API was developed by Northwestern Medicine and Dexcom to address these challenges. Here, we describe the data management steps and user interface of the integrated system. Providers can access patients' historical and latest daily CGM data in the form of modal day plots and stacked columns showing time in various glucose concentration ranges. The integration facilitates the acquisition, storage, analysis, and display of CGM data within an EHR system and may be appropriate for deployment in other health care facilities.

Design of Behavioral Economic Applications to Geriatrics Leveraging Electronic Health Records (BEAGLE): A pragmatic cluster randomized controlled trial

BACKGROUND

Overtesting and treatment of older patients is common and may lead to harms. The Choosing Wisely campaign has provided recommendations to reduce overtesting and overtreatment of older adults. Behavioral economics-informed interventions embedded within the electronic health record (EHR) have been shown to reduce overuse in several areas. Our objective is to conduct a parallel arm, pragmatic cluster-randomized trial to evaluate the effectiveness of behavioral-economics-informed clinical decision support (CDS) interventions previously piloted in primary care clinics and designed to reduce overtesting and overtreatment in older adults.

METHODS/DESIGN

This trial has two parallel arms: clinician education alone vs. clinician education plus behavioral-economics-informed CDS. There are three co-primary outcomes for this trial: (1) prostate-specific antigen (PSA) screening in older men, (2) urine testing for non-specific reasons in older women, and (3) overtreatment of diabetes in older adults. All eligible primary care clinics from a large regional health system were randomized using a modified constrained randomization process and their attributed clinicians were included. Clinicians were recruited to complete a survey and educational module. We randomized 60 primary care clinics with 374 primary care clinicians and achieved adequate balance between the study arms for prespecified constrained variables. Baseline annual overuse rates for the three co-primary outcomes were 25%, 23%, and 17% for the PSA, urine, and diabetes measures, respectively.

DISCUSSION

This trial is evaluating behavioral-economics-informed EHR-embedded interventions to reduce overuse of specific tests and treatments for older adults. The study will evaluate the effectiveness and safety of these interventions.

Colonoscopy education delivered via the patient portal does not improve adherence to scheduled first-time screening colonoscopy

Background and study aims  Non-adherence to scheduled colonoscopy burdens endoscopic practices and innovative approaches to improve adherence are needed. We aimed to assess the effect of an educational video emphasizing colonoscopy importance delivered through the electronic health record patient portal upon "no-show" and late cancellation rates (non-adherence) in patients scheduled for first-time screening colonoscopy. Patients and methods  We conducted a single center randomized controlled trial among patients scheduled for their first screening colonoscopy. Patients were randomized to routine care ("control") or video education ("video"). Control patients received a portal message 14 days prior to colonoscopy date; video patients additionally received a link to the educational video. Results  In total, 830 patients (59 % female, median age 55 years) were randomized ("control": 406; "video": 424). Nearly all (88 %) opened the message; in the video arm, most (72 %) watched a majority of the video. Overall, 80 % attended their scheduled colonoscopy appointment (late cancel: 18 %, "no show": 1 %) and 90 % underwent colonoscopy within 3 months of appointment. Adherence rates did not differ between video and control arms for the scheduled appointment (OR 1.2, CI 0.9-1.8) or for colonoscopy within 3 months of scheduled appointment (OR 1.3, CI 0.8-2.1). Bowel preparation quality did not differ between the groups. Conclusion  Most patients scheduled for colonoscopy will open a patient portal message and, when delivered, watch an educational video. However, delivery of an educational video two weeks prior to screening colonoscopy appointment did not improve adherence.

Quantitative measure of muscle strength and size in chronic alcoholism: an early indication of tissue damage

We measured quadriceps strength and thickness in 101 male alcoholic patients and in 58 controls in order to investigate the force-size relationships of skeletal muscle in an alcoholic population. The relationship of these parameters with the duration of alcoholism, nutritional status and biochemical and haematological markers of heavy chronic alcohol use was investigated. Alcohol consumption of more than 42 standard drinks (420 g alcohol) per week for at least 5 years is associated with muscle weakness and wasting. There was no evidence of under-nutrition in these alcoholic subjects and muscle wasting occurred independently of peripheral neuropathy, a history of muscle pain, abnormalities of liver enzymes and elevation of mean red cell corpuscular volume. Quantitation of muscle size and strength in heavy drinkers may provide a useful early indicator of health impairment in alcoholics.

Twin study of central auditory processing disorder

We compared auditory, cognitive, and language test results in a pair of dizygotic twins, one of whom showed symptoms of central auditory processing disorder (CAPD). Results highlight the importance of testing binaural function. In particular, electrophysiologic measures of dichotic listening effectively demonstrated the auditory-specific nature of this child's listening problems. The importance of a thorough and comprehensive evaluation of children suspected of CAPD is stressed.

Comparison of performance with frequency transposition hearing aids and conventional hearing aids

Four experienced hearing aid users were evaluated using a frequency transposition (TranSonic) hearing system. Following a trial period, the Abbreviated Profile of Hearing Aid Performance (APHAB) and a variety of speech audiometric measures were used to compare the frequency transposition fitting with each subject's conventional hearing aids. A single-subject study design with a series of repeated measures permitted statistical analysis of differences in performance with the various amplification strategies. Two of the four subjects demonstrated statistically significant benefit with the frequency transposition device. Results show the efficacy of frequency transposition in improving speech understanding and quality of life in some individuals with severe-to-profound hearing loss. Overall, results suggest the need for evaluating the benefit of frequency transposition on an individual basis.

Comparison of performance with frequency transposition hearing aids and conventional hearing aids

Four experienced hearing aid users were evaluated using a frequency transposition (TranSonic) hearing system. Following a trial period, the Abbreviated Profile of Hearing Aid Performance (APHAB) and a variety of speech audiometric measures were used to compare the frequency transposition fitting with each subject's conventional hearing aids. A single-subject study design with a series of repeated measures permitted statistical analysis of differences in performance with the various amplification strategies. Two of the four subjects demonstrated statistically significant benefit with the frequency transposition device. Results show the efficacy of frequency transposition in improving speech understanding and quality of life in some individuals with severe-to-profound hearing loss. Overall, results suggest the need for evaluating the benefit of frequency transposition on an individual basis.

Factor analytic structure of auditory impairment in elderly persons

The audiometric and self-assessed handicap data of 180 elderly persons with presbyacusic-type hearing impairment were submitted to principal components analysis in order to study the factor structure underlying auditory processing. Audiometric data included pure-tone threshold sensitivity, speech understanding scores for monosyllabic words without competition, synthetic sentences within competition, and dichotic synthetic sentence identification. The Hearing Handicap Inventory for the Elderly (HHIE) was used to quantify self-assessed handicap both by the subjects and by their significant others. Six factors emerged from the analysis: (1) low-frequency sensitivity loss, (2) high-frequency sensitivity loss, (3) general speech understanding ability, (4) self-assessed handicap, (5) the central processing of left ear input, and (6) the central processing of right ear input. Five conclusions are highlighted: (1) degree of hearing sensitivity loss, which determines speech audibility, remains a key concept in understanding the speech understanding problems of elderly persons; (2) low-frequency and high-frequency sensitivity loss emerge as separate factors; (3) a factor of general speech understanding ability, not strongly related to audibility, is confirmed; (4) the central processing of right and left ear verbal inputs emerge as separate factors; and (5) perceived auditory handicap emerges as a separate factor, apparently not strongly related to either audibility, general speech understanding, or the central processing of verbal input.

Electrophysiologic indices of Stroop and Garner interference reveal linguistic influences on auditory and visual processing

The purpose of this study was to examine linguistic influences on the auditory and visual processing of words both behaviorally and electrophysiologically. Our task yielded measures of the effect of irrelevant semantic content (Stroop interference) and of the effect of irrelevant linguistic variability (Garner interference). The behavioral results allow us to assess whether the linguistic and nonlinguistic dimensions of verbal stimuli are processed dependently or independently. The electrophysiologic results allow us to determine where any processing interactions are arising, particularly regarding perceptual versus postperceptual underpinnings, and to evaluate the similarity and dissimilarity between the two interference effects. Results show pronounced Stroop and Garner interference both behaviorally and electrophysiologically, indicating linguistic influences on auditory and visual processing. Subjects could not ignore the irrelevant linguistic dimension and attend selectively to the physical dimension of either spoken or written words. The results indicate that the physical and linguistic dimensions of words are not processed independently. With regard to the stage of processing underlying the interference effects, our results suggest that both Stroop and Garner interference involve multiple stages of processing. The two interference effects are not duplicate measures, however, and different electrophysiologic signatures were observed. Stroop interference is characterized by perceptual and postperceptual components. Similar electrophysiologic patterns within the auditory and visual modalities suggest that each interference effect is tapping similar processes for spoken and written stimuli.

Unsuccessful use of binaural amplification by an elderly person

An elderly person who preferred and performed better with monaural than with binaural amplification was extensively studied, both audiologically and neuropsychologically, in search of an explanation for the phenomenon. Particular emphasis was placed on the study of dichotic speech perception, both behaviorally and electrophysiologically. Results suggest that age-related changes in interhemispheric transfer of auditory input via corpus callosum may underlie the preference for monaural amplification. Implications for the evaluation of amplification potential in elderly persons are discussed.

Comparison of conventional amplification and an assistive listening device in elderly persons

OBJECTIVE

To assess the impact of personal amplification systems on quality of life of elderly persons and to compare conventional hearing aid with assistive listening device.

DESIGN

Audiologic, neuropsychologic, and quality-of-life measures were prospectively administered to 180 elderly, hearing-impaired persons before and after randomized 6 wk trials of four treatment conditions-a no-amplification condition and three different types of amplification: 1) conventional hearing aid, 2) assistive listening device, and 3) a combination of the two systems. All subjects volunteered to participate in a study comparing different amplification systems and were paid for their participation.

RESULTS

Both self-perceived handicap and speech understanding were improved significantly by all three amplification systems. There were no significant group differences between new users and previous users of amplification in self-assessed handicap after amplification use. Anecdotally, subjects preferred the sound quality of the assistive listening device, but an overwhelming majority (97.3%) still chose the conventional aid for use in daily living.

CONCLUSIONS

Results affirm the significant impact of amplification on the quality of life of elderly persons. The strong preference for the conventional hearing aid in everyday use undoubtedly reflects the fact that elderly users usually are not willing to endure the difficulties associated with the use of remote-microphone systems.

Hearing aid use, central auditory disorder, and hearing handicap in elderly persons

We compared self-reported handicap (Hearing Handicap Inventory for the Elderly, HHIE) scores before and after a 6-week period of hearing aid use in subjects drawn from a pool of 115 elderly persons with hearing impairment. Study patients (PTs) were divided into two categories according to whether scores on a dichotic listening test (Dichotic Sentence Identification Test, DSI) were normal or abnormal. In a subgroup of 63 persons who had not previously used amplification, subjects in the two DSI categories showed equivalent average HHIE scores. After 6 weeks of first-time hearing aid use, there was a significant improvement in average HHIE scores, but only in the DSI-normal category. In the subgroup with dichotic deficits (DSI-abnormal group), average HHIE scores did not change significantly after hearing aid use. In a subgroup of 89 PTs, we compared the self-assessed HHIE scores of the PTs with the HHIE scores rated by their significant others (SOs). In both DSI categories, the average handicap, as judged by the subject's SO, was significantly greater than the handicap as judged by the PT. In addition, both ratings reflected significant improvement after hearing aid use. It was the case, however, that improvement consequent on amplification was significantly smaller for subjects in the DSI-abnormal category. Finally, we show, in the entire pool of 115 PTs, that the effect of practice on the HHIE score is not sufficient to explain the improvement after amplification. Results affirm both the positive value of amplification and the negative impact of central auditory deficit as they affect the HHIE scores of the elderly hearing-impaired person.

Dichotic listening, event-related potentials, and interhemispheric transfer in the elderly

OBJECTIVE

To determine the basis for the large, age-related asymmetries in dichotic listening performance scores reported by Jerger et al. (1994).

DESIGN

Behavioral and electrophysiologic responses to dichotic listening tasks in both verbal and nonverbal paradigms were obtain in four groups of subjects: young adults with normal hearing, elderly persons with presbyacusis, elderly persons with presbyacusis and marked dichotic deficits, and patients with lesions of the corpus callosum.

RESULTS

In comparison with the young group the two elderly groups showed an increasing left-ear deficit on the verbal task, and an increasing right-ear deficit on the nonverbal paradigm. The pattern of results obtained in the elderly persons with marked dichotic deficits was similar to the pattern of results in the group with callosal lesions.

CONCLUSIONS

With age, there may be a significant loss of efficiency of interhemispheric transfer of auditory information through the corpus callosum. Such age-related deficit might have important implications for the effective use of binaural information by elderly person.

Hearing impairment in older adults: new concepts

OBJECTIVE

To review present information about the epidemiology, etiologies, pathogenesis, evaluation, and quality of life aspects of hearing loss and to present an approach to rehabilitation for hearing loss in older adults.

DESIGN

A survey of recent findings on the problem of hearing loss in older adults, efficacy of intervention with amplification, and new developments in intervention strategies.

CONCLUSIONS

The complex nature of hearing problems in older adults involves changes in the auditory periphery as well as in the central mechanisms for processing sound input. These changes affect the social and emotional impact of the hearing disorder. The importance of understanding the many implications of hearing loss on quality of life is emphasized. Both older adults and immediate family members need information and advice about the consequences of age-related hearing loss. The physician has a key role in helping them to overcome negative attitudes toward a hearing handicap. For most older persons, hearing aids alleviate many of the handicaps of hearing impairment. For some older persons who do not benefit adequately from conventional hearing aids, assistive listening devices may be helpful. Many old persons and their relatives are reluctant to confront the reality of hearing handicap and try to hide the fact that they need sound amplification. One important future direction is to foster acceptance of hearing loss and to support the more open use of amplification systems.

Quantifying improvement with amplification

We employed a nonparametric measure, the randomization test, to evaluate, statistically, a variety of speech understanding measures used to quantify the efficacy of different intervention strategies in five clinical patients. The flexibility of the approach was demonstrated by comparing monaural with binaural amplification, a conventional aid with an assistive listening device, and a cochlear implant alone versus a cochlear implant supplemented by visual cues. The randomization test allows statistical analysis of differences in performance at the level of the individual subject. This approach may be useful in addressing accountability when recommending a specific intervention strategy for a particular hearing-impaired individual.

Effects of age and gender on dichotic sentence identification

There is converging evidence that aging causes a progressive decline in the central processing of speech and that this decline is greater for left-ear than for right-ear input. In the present paper we investigated, by means of a dichotic sentence identification paradigm, some parameters of the "left-ear effect." We analyzed the clinical records of 356 individuals, 203 males and 153 females, to whom the Dichotic Sentence Identification (DSI) Test had been administered as part of routine audiometric assessment. Subjects ranged in age from 9 to 91 yr. The DSI test was always carried out in two modes: free report (FR) and directed report (DR). In the FR mode the subject reported what was heard in both ears. In the DR mode the subject reported only what was heard in one precued ear. In half of the trials the right ear was precued, in the other half the left ear was precued. Findings confirm a progressively larger right-ear advantage, or left-ear deficit, with increasing age. We document this effect in both the FR and DR modes, then demonstrate that the effects cannot be attributed to interaural asymmetries in threshold sensitivity. Comparison of male and female data suggest a gender difference in the effect of age on the left-ear deficit. Males show a larger effect then females in both modes of test administration. Finally, we propose a model of dichotic listening performance that attempts to explain ear asymmetry as the linear combination of an auditory/structural component and a task-related/cognitive component. We then show how these hypothetical components change with age in the present sample.

Some factors affecting assessment of hearing handicap in the elderly

In 42 elderly hearing-impaired persons we compared the patient's self-assessment of hearing handicap with the assessment made by the patient's significant other. In general, patients tended to rate themselves as less handicapped than did their significant others. The difference was not affected by degree of loss but was affected by slope of loss and by the presence of central auditory processing deficit. Results support the value of the handicap assessment by the significant other in understanding the communication problems of the elderly patient.

Case studies in binaural interference: converging evidence from behavioral and electrophysiologic measures

We present four case reports of elderly hearing-impaired persons demonstrating a binaural interference effect. Performance measures were poorer when stimulation was binaural than when it was monaural. In the first case the effect is shown for aided speech recognition scores. In the second case it is shown in topographic brain maps of the middle-latency auditory evoked potential. In the third and fourth cases it is shown for both aided speech recognition and the middle-latency response. The effect may be analogous to the phenomenon of binocular rivalry in the visual domain.

Gender affects audiometric shape in presbyacusis

A review of large-scale surveys of hearing over the past 50 years reveals a "gender-reversal" phenomenon in the average audiograms of the elderly. Above 1 kHz males show greater average loss than females, but below 1 kHz females show greater average loss than males. The effect increases with both age and degree of hearing loss. The difference is present whether or not the elderly persons complain of a hearing problem and remains after persons with a history of noise exposure are excluded from the analysis. A possible explanation, based on the greater likelihood of cardiovascular disease in the elderly female, is considered.

Non-dilated urinary tract obstruction

OBJECTIVE

To describe the occurrence of obstructive uropathy in the absence of dilatation of the urinary tract.

CLINICAL FEATURES

Five cases of non-dilated obstructive nephropathy are described. All patients were uraemic on presentation. Obstruction was caused by retroperitoneal malignancy in two patients and uric acid lithiasis in the remaining three. All patients had at least one ultrasound examination. Isotope renography and computed tomography were performed in three and four patients respectively. None of these imaging techniques suggested obstruction in any of the cases. Radionuclide scans were characterised by unusually poor perfusion and parenchymal phase images.

INTERVENTION AND OUTCOME

An immediate diuresis and a rapid return of normal renal function occurred after relief of the obstruction in all cases.

CONCLUSION

The absence of dilatation in obstructive nephropathy is uncommon but may be responsible for delayed diagnosis and management of a readily treatable cause of acute renal failure.

Identification of the site of severe colon bleeding by technetium-labeled red-cell scan

In cases of severe colon bleeding, it is more important to know the site than the cause, in case surgery is required. Technetium-labeled red-cell scan (TLRCS) is known to identify the site of bleeding at the rate of 0.1 ml per minute or more. The aim of this retrospective study was to see whether TLRCS was a reliable indicator of the site of severe colon bleeding. A retrospective study was made of patients investigated in this way for acute, severe colon bleeding at St. Vincent's Hospital, Melbourne, from 1984 to 1988 (five years). TLRCS identified the site of bleeding in less than half of the cases but correctly identified the site in all nine patients in whom bleeding was so severe as to require emergency surgery, avoiding total colectomy in eight cases.

Speech tracking in the evaluation of a multichannel cochlear prosthesis

Individual speech tracking data were analyzed in relation to other variables in 11 adult users of the Nucleus multichannel cochlear implant. Patients were categorized according to postoperative speech tracking results. The resultant groups could also be differentiated on the basis of postoperative MAC scores, surgeon's rating of overall success, and duration of deafness before implantation. The speech tracking paradigm appears to be a useful technique for the evaluation of performance with a cochlear prosthesis.

Electrically Elicited Stapedius Reflex and Preferred Listening Level in a Patient with a Cochlear Implant

In a patient with a multichannel cochlear implant, it was possible to demonstrate stapedial reflex contraction to intracochlear electrical stimulation. Using a standard immittance measurement technique, characteristics of the electrically evoked reflex were compared to analogous characteristics of the acoustically evoked reflex. Latency-intensity functions were similar for the two modes of excitation, but reflex waveform morphology and amplitude growth functions were different. The effects of electrode position and electrode spacing were of particular interest. In our patient, neither position nor spacing affected onset latency. Both electrode position and electrode spacing did, however, affect reflex amplitude. As position moved from base to apex, reflex amplitude increased systematically and substantially. Although we have reported amplitude results in suprathreshold current level, we also found the same relationship across electrode position for stimulation at constant current level. Reflex amplitude by electrode spacing was also affected. The widest spacing (3 mm) produced the largest reflex amplitude, and the narrowest spacing (1.5 mm) produced the smallest amplitude. The spacing effect, however, showed a strong interaction with electrode position, being greatest at the apical position and least at the basal position.

Rate and filter dependence of the middle-latency response in infants

Auditory evoked-potential activity in the 0 to 100-ms latency range was explored using wide-band filtering and a range of stimulus rates, in 8 babies ranging in age from 2 to 6 months. We observed both a stable early positive peak, in the 10 to 15-ms region, and a rate-dependent, positive peak at about 50 ms in all 8 babies. The latter response was best observed at rates of 1-2.5 stimuli/s and seldom observed at rates above 4/s. This peak may represent a developmentally early version of the Pa peak of the adult middle-latency response.

Effect of sleep on the auditory steady state evoked potential

The effects of both natural and sedated sleep on the auditory steady state evoked potential (SSEP) were evaluated in nine normal-hearing subjects. Both absolute amplitude and phase variability measures were obtained by Fourier analysis of successive samples of the averaged SSEP waveform. Amplitude decreased significantly in the sleeping state but phase variability was not substantially altered. Because it does not seem to be affected by sleep, phase variability of the SSEP is suggested as a potentially useful technique for predicting threshold sensitivity.

Renal impairment and its reversibility following variable periods of complete ureteric obstruction

There is debate concerning the time course and degree of recovery possible after relief of complete unilateral ureteric obstruction. This study in dogs investigates these features. One ureter was occluded for varying periods, and then reimplanted into the bladder. Recovery was monitored by Tc-Sn-labelled diethylene triamine penta acetic acid (D.T.P.A.) scans and renograms together with creatinine clearance studies. The morphological changes were also studied. There was found to be a progressive loss of functional recovery with increasing periods of obstruction, though this was dramatically improved by contralateral nephrectomy once recovery had stabilized. Increased radial scarring developed in the kidney following increasing periods of obstruction.

Detection of deep venous thrombosis by scanning of 99mtechnetium-labelled red-cell venous pool

A comparative study of 32 patients with suspected deep venous thrombosis was carried out using blood-pool radionuclide scanning and conventional x-ray phlebography. Results of the two methods showed close agreement, the sensitivity (positive correlation) of the scan being 100% and its specificity 89%. We conclude that a patient's red cells labelled with 99mtechnetium (99mTc) provide an excellent medium for this type of scanning. The technique has particular advantages in visualising the whole venous system, giving a persisting image, and obviating the need to inject into a vein of the affected limb. In view of the inherent disadvantages of contrast phlebography, 99mTc-red-cell scanning is clearly an acceptable alternative.

Localization of a phaeochromocytoma situated in the pelvis by radionuclide scanning

Accurate localization of an extra-adrenal (pelvic) phaeochromocytoma was achieved by radionuclide scanning using 99 Tcm-Sn-DTPA. This facilitated the planning of the surgical approach and the subsequent removal of the tumour.