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PubMed2005

Wireless sensors powered by microbial fuel cells.

Monitoring parameters characterizing water quality, such as temperature, pH, and concentrations of heavy metals in natural waters, is often followed by transmitting the data to remote receivers using telemetry systems. Such systems are commonly powered by batteries, which can be inconvenient at times because batteries have a limited lifetime and must be recharged or replaced periodically to ensure that sufficient energy is available to power the electronics. To avoid these inconveniences, a microbial fuel cell was designed to power electrochemical sensors and small telemetry systems to transmit the data acquired by the sensors to remote receivers. The microbial fuel cell was combined with low-power, high-efficiency electronic circuitry providing a stable power source for wireless data transmission. To generate enough power for the telemetry system, energy produced by the microbial fuel cell was stored in a capacitor and used in short bursts when needed. Since commercial electronic circuits require a minimum 3.3 V input and our cell was able to deliver a maximum of 2.1 V, a DC-DC converter was used to boost the potential. The DC-DC converter powered a transmitter, which gathered the data from the sensor and transmitted it wirelessly to a remote receiver. To demonstrate the utility of the system, temporal variations in temperature were measured, and the data were wirelessly transmitted to a remote receiver.

Bioelectric Energy Sources↗

PubMed2006

High power density from a miniature microbial fuel cell using Shewanella oneidensis DSP10.

A miniature microbial fuel cell (mini-MFC) is described that demonstrates high output power per device cross-section (2.0 cm2) and volume (1.2 cm3). Shewanella oneidensis DSP10 in growth medium with lactate and buffered ferricyanide solutions were used as the anolyte and catholyte, respectively. Maximum power densities of 24 and 10 mW/m2 were measured using the true surface areas of reticulated vitreous carbon (RVC) and graphite felt (GF) electrodes without the addition of exogenous mediators in the anolyte. Current densities at maximum power were measured as 44 and 20 mA/m2 for RVC and GF, while short circuit current densities reached 32 mA/m2 for GF anodes and 100 mA/m2 for RVC. When the power density for GF was calculated using the cross sectional area of the device or the volume of the anode chamber, we found values (3 W/m2, 500 W/m3) similar to the maxima reported in the literature. The addition of electron mediators resulted in current and power increases of 30-100%. These power densities were surprisingly high considering a pure S. oneidensis culture was used. We found that the short diffusion lengths and high surface-area-to-chamber volume ratio utilized in the mini-MFC enhanced power density when compared to output from similar macroscopic MFCs.

Anthraquinones↗

PubMed1997

A randomized comparison of fixed power and temperature monitoring during slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia.

Temperature monitoring may be helpful for ablation of accessory pathways, however its role in ablation of atrioventricular nodal reentrant tachycardia (AVNRT) using the slow pathway approach is unclear. Therefore, the purpose of this study was to prospectively compare slow pathway ablation for AVNRT using fixed power or temperature monitoring. The study included 120 patients undergoing ablation for AVNRT. Patients were randomly assigned to receive either fixed power at 32 watts, or to temperature monitoring with a target temperature of 60 degrees C. The primary success rate was 72% in the fixed power group and 95% in the temperature monitoring group (p = 0.001). The ablation procedure duration (35 +/- 29 min vs 35 +/- 30 min; p = 0.9), fluoroscopic time (32 +/- 17 vs 35 +/- 19 min; p = 0.4), mean number of applications (10.2 +/- 8.1 vs 8.4 +/- 7.9; p = 0.2), and coagulum formation per application (0.2% vs 0.5%; p = 0.6) were statistically similar in the fixed power and temperature monitoring groups, respectively. The mean temperature (47.3 +/- 4.8 degrees C vs 48.6 +/- 3.8 degrees C; p < 0.01), and the temperature associated with junctional ectopy (48.2 +/- 3.8 degrees C vs 49.3 +/- 3.6 degrees C, p < 0.01) were less for the fixed power than the temperature monitoring group. In the temperature monitoring group, only 31% of applications achieved an electrode temperature of 60 degrees C. During follow up of 6.6 +/- 3.6 months there were two recurrences in the fixed power group and one in the temperature monitoring group (p = 1.0). In summary, power titration directed by temperature monitoring was associated with an improved primary procedural success rate. Applications of energy were associated with a temperature of approximately 50 degrees C with both techniques, suggesting that there is a low efficiency of heating in the posterior septum.

Adult↗

PubMed1998

A comparison of power to detect a QTL in sib-pair data using multivariate phenotypes, mean phenotypes, and factor scores.

The power to detect a quantitative trait locus (QTL) in sib-pair data is investigated. We assume that we have at our disposal 3 or 4 related phenotypic measures in a sample of sib-pairs. Individual differences in these phenotypes are due to a common QTL and specific (i.e., unique to each phenotype) nonshared environmental and specific polygenic additive effects. In addition, models are considered that include common nonshared environmental effects and/or common polygenic additive effects. We calculate the power to detect the QTL in a genetic covariance structure analysis of the multivariate data, of the mean phenotypic data, and of factor scores. The use of factor scores is shown to be universally more powerful than the use of multivariate or mean phenotypic data. We also investigate the effect of using a single sample of sib-pairs to both calculate the factor score regression matrix and to carry out the QTL analysis. The use of a single sample to both these ends results in a loss of power compared to the theoretical, expected power. The gain in power attributable to the use of factor scores, however, outweighs this observed loss in power. The advantages of using factor scores in selecting sib-pairs are discussed.

Chi-Square Distribution↗

PubMed1998

The functional significance of absolute power with respect to event-related desynchronization.

The question is examined whether the extent of changes in relative band power as measured by event-related desynchronization (ERD) depends on absolute band power. The results for target stimuli of a simple oddball task indicate that the prestimulus (reference) level of absolute band power has indeed a strong influence on ERD. Whereas for the alpha band large band power in the reference interval is related to a strong degree of alpha suppression as measured by ERD, the opposite holds true for the theta band. Here, a low level of band power during the reference interval is related to a pronounced increase in band power during the processing of the target stimulus. In contrast to alpha and theta, ERD in the delta band is not influenced by the magnitude of band power in the reference interval.

Adolescent↗

PubMed1990

Statistical power of psychological research: what have we gained in 20 years?

Power was calculated for 6,155 statistical tests in 221 journal articles published in the 1982 volumes of the Journal of Abnormal Psychology, Journal of Consulting and Clinical Psychology, and Journal of Personality and Social Psychology. Power to detect small, medium, and large effects was .17, .57, and .83, respectively. 20 years after Cohen (1962) conducted the first power survey, the power of psychological research is still low. The implications of these results concerning the proliferation of Type I errors in the published literature, the failure of replication studies, and the interpretation of null (negative) results are emphasized. An example is given of the use of power analysis to help interpret null results by setting probable upper bounds on the magnitudes of effects. Limitations of statistical power analyses, suggestions for future research, sources of computational information, and recommendations for improving power are discussed.

Humans↗

PubMed2004

Validation of Orbscan II posterior corneal curvature measurement for intraocular lens power calculation.

AIMS: To validate the use of Orbscan II slit-scanning topography for measuring posterior corneal curvature, by comparing corneal power calculations using this value with the standard keratometric method of corneal power calculation. METHOD: Corneal measurements were taken from both eyes of 15 normal subjects using the Javal-Schiotz keratometer and the Orbscan II topographer. Corneal power was calculated using standard keratometric indices of 1.337.5 or 1.331.5 and Javal-Schiotz keratometry. Corneal power was then recalculated using the thick-lens formula, with anterior corneal curvature from the Javal-Schiotz or Orbscan II and posterior measurements from the Orbscan II; in addition, the 3.0 mm 'Mean Power' value from the Orbscan II software was noted. Six comparisons were then made using mean-difference plots. RESULTS: The smallest difference and therefore the most predictable agreement was between Javal-Schiotz keratometry using a refractive index of 1.331.5 and the thick-lens formula using Javal-Schiotz anterior curvature and Orbscan II posterior curvature. The mean difference was 0.27 D with a confidence interval of 0.02-0.52 D. CONCLUSIONS: In normal eyes, data on posterior corneal curvature from the Orbscan II can be used to calculate corneal power in close agreement with the standard keratometric method. This suggests the use of the Orbscan II in eyes that have previously undergone refractive surgery, for calculation of intraocular lens power prior to cataract surgery.

Biometry↗

PubMed1992

Leg extensor power and functional performance in very old men and women.

1. Residents of a chronic care hospital (13 men of mean age 88.5 +/- 6 SD years and 13 women of mean age 86.5 +/- 6 SD years) who had multiple pathologies were assessed for leg extensor capability in several ways. 2. A custom-built rig was used to assess leg extensor power, that is, maximal power output over less than 1 s in a single extension of one leg. Performance measures were obtained by timing chair rises (from a standard chair 0.43 m high), stair climbing (four risers, total height 0.635 m) and a walk (6.1 m). For each measurement the best of several trials were recorded as definitive. 3. Leg extensor power was significantly correlated with all performance measures, but the performance measures were not related to each other except for chair rising and walking speed. 4. Women had significantly less extensor power than men, but their power explained more of the variance in performance, e.g. power accounted for 86% of the variance in walking speed. 5. There was no relation within the group between age and any of the variables measured. 6. Measurement of leg extensor power in frail elderly people may prove useful in focusing effective rehabilitation programmes.

Aged↗

PubMed2003

Increasing power versus duration for radiofrequency ablation with a high superfusate flow: implications for pulmonary vein ablation?

Radiofrequency (RF) ablation of pulmonary veins (PVs) is a new treatment for atrial fibrillation. Low energy ablation is usually used for this procedure. The effect of superfusate flow on lesion formation in this setting has not been studied previously. We examined lesion dimensions and intramural temperatures with varying powers and duration of RF application in this high flow environment. Ablation of fresh bovine hearts was performed with a 4-mm tip RF catheter in temperature control mode, target temperature 50 degrees C. At power levels of 20 W, 30 W, 40 W, and 50 W, effects of PV flow (no flow or 1 L/min) and 60- and 120-second durations were tested. Tissue temperatures were recorded at depths of 1, 4, 7, and 10 mm. Without flow, no lesions were created. The lowest power setting for lesion creation was 30 W at 60 seconds and 20 W at 120 seconds. Increasing power from 30 W to 50 W for 60 seconds increased lesion depth 0.7 mm (SE 0.3), P = 0.03 and 2.5 mm (SE 0.6), P = 0.003, at 120 seconds. Increasing RF application duration from 60 to 120 seconds increased depth for 30 W by 0.9 mm (SE 0.5), P = NS, 40 W 1.7 mm (SE 0.4), P = 0.002, and 50 W 2.6 mm (SE 0.5), P < 0.001. Power of 50 W for 60 seconds and >30 W for 120 seconds created lesions deeper than the wall thickness of a PV. Flow is necessary for creation of lesions with low power, low tip temperature RF ablation. When a resistant site to ablation is encountered, increasing duration of ablation is best for increasing lesion depth. Higher power has the potential to create lesions deeper than the PV wall and may increase the risk of complications.

Animals↗

PubMed2002

An algorithm including results of gray-scale and power Doppler ultrasound examination to predict endometrial malignancy in women with postmenopausal bleeding.

OBJECTIVE: To determine if power Doppler ultrasound examination of the endometrium can contribute to a correct diagnosis of endometrial malignancy in women with postmenopausal bleeding and endometrium > or = 5 mm. METHODS: Eighty-three women with postmenopausal bleeding and endometrium > or = 5 mm underwent gray-scale and power Doppler ultrasound examination using predetermined, standardized settings. Suspicion of endometrial malignancy at gray-scale ultrasound examination (endometrial morphology) was noted, and the color content of the endometrium at power Doppler examination was estimated subjectively (endometrial color score). Computer analysis of the most vascularized area of the endometrium was done off-line in a standardized manner. Stepwise multivariate logistic regression analysis was carried out to determine which subjective and objective ultrasound and power Doppler variables satisfied the criteria to be included in a model to calculate the probability of endometrial malignancy. RESULTS: Endometrial thickness, vascularity index (vascularized area/endometrial area), and use of hormone replacement therapy (HRT) satisfied the criteria to be included in the model used to calculate the 'objective probability of endometrial malignancy'. Endometrial morphology, endometrial color score and HRT use satisfied the criteria to be included in the model to calculate the 'subjective probability of malignancy'. Endometrial thickness > or = 10.5 mm had a sensitivity with regard to endometrial cancer of 0.88 and a specificity of 0.61. At a fixed sensitivity of 0.88, the specificity of the 'objective probability of malignancy' (0.81) was superior to all other ultrasound and power Doppler variables (P = 0.001-0.02). The 'objective probability of malignancy' detected more malignancies at endometrium 5-15 mm than endometrial morphology (5/7 vs. 1/7, i.e. 0.71 vs. 0.14; P = 0.125) with a similar specificity (49/57 vs. 51/57, i.e. 0.86 vs. 0.89). CONCLUSION: Power Doppler ultrasound can contribute to a correct diagnosis of endometrial malignancy, especially if the endometrium measures 5-15 mm. The use of regression models including power Doppler results to estimate the risk of endometrial cancer deserves further development.

Aged↗

PubMed2002

Age-related differences in lower extremity power after support surface perturbations.

OBJECTIVES: The purpose of this study was to examine a comprehensive measure relating to the ability to generate, absorb, and transfer mechanical energy introduced by a perturbation. It was hypothesized that this measure would reveal age-related differences leading to different balance recovery responses (i.e., feet-in-place and compensatory step). DESIGN: Cross-sectional, descriptive study. SETTING: The Motor Control Laboratory at the University of Oregon. PARTICIPANTS: Eighteen younger (aged 18-35) and 21 older (aged 65-85) women received forward and backward support surface translations of varying amplitudes and velocities. MEASUREMENTS: Lower extremity peak positive joint power and peak negative muscle power were examined at the largest perturbation in which a feet-in-place response was used and the subsequent perturbation where a step occurred. Peak positive joint power depicts the maximum rate of passive transfer of energy into a segment and is indicative of the maximum destabilization of that segment. Peak negative muscle power is the maximum rate of energy absorption by muscle, which reduces the effect of the perturbation on the segment. RESULTS: After a backward perturbation, there was a significant main effect of age for muscle power and a significant main effect of response type for joint power. For the forward condition, there was a significant main effect of response type for muscle power only. CONCLUSIONS: The mechanical reason for the emergence of the compensatory step after support-surface perturbations is clear; the feet-in-place response is energetically more demanding than the compensatory step. The energy analysis suggests a mechanical basis as one reason for older adults' reliance on the compensatory step: older adult muscles absorb less energy. The results of this study also highlight the importance of the proximal knee and hip musculature versus the distal ankle musculature.

Adolescent↗

PubMed2001

Peak exercise cardiac power output; a direct indicator of cardiac function strongly predictive of prognosis in chronic heart failure.

OBJECTIVES: This study assessed the prognostic value of peak cardiac power output, measured non-invasively during maximal cardiopulmonary exercise testing, against other exercise-derived haemodynamic variables in patients with chronic congestive heart failure. METHOD AND RESULTS: Two hundred and nineteen unselected, consecutive patients with congestive heart failure (166 men, mean (+/-SD) age of 56+/-13 years) who underwent maximal symptom limited cardiopulmonary treadmill exercise testing with non-invasive estimation of cardiac output using carbon dioxide re-breathing techniques, were followed-up for a mean period of 4.64 (4.47--4.82, 95% CI) years. Cardiac power output was calculated from the product of cardiac output and mean arterial blood pressure. All cause mortality was 12.3% (27 deaths). Peak and resting cardiac power output, peak mean arterial blood pressure, peak and resting cardiac output and peak VO(2)were all predictive of outcome on univariate analyses. Peak cardiac power output, either entered continuously or categorically with a cut-off value of 1.96 watts, was the only independent predictor of mortality (P=0.0004 for values < or >1.96 watts and P=0.001 for continuous values) using multivariate analysis. A relative risk ratio of 5.08 (1.94-13.3, 95% CI) was obtained for a cardiac power output <1.96 watts. CONCLUSION: Peak cardiac power output is an independent predictor of mortality that can be measured non-invasively using cardiopulmonary exercise testing. It can give further prognostic power to a peak VO(2)in the assessment of patients with congestive heart failure.

Adult↗

PubMed1999

Measurement of maximal power output in isokinetic and non-isokinetic cycling. A comparison of two methods.

The main goal of the study was to compare maximal power output and power output at different pedalling frequencies obtained during isokinetic all-out tests with maximal power output obtained during a single all-out sprint (against the same braking force for every subject). Sixty healthy male subjects participated in the study. The ergometer system used in this study has three operating modes: the isokinetic mode (maintaining pedal crank velocity constant at a present level), a revolution dependent mode and a revolution independent mode. In all three operating modes the effective forces are monitored by means of strain gauge. All subjects performed a single all-out sprint against a braking force of 20 Newton and an all-out isokinetic cycling test consisting of ten 10 s bouts of maximal cycling at speeds ranging from 50 rpm to 140 rpm. In both tests, irrespective of which test mode was used, the mean power for a complete crank revolution showed parabolic relationships to crank velocity. For the isokinetic test, the subjects showed a peak power (IsoWpeak) of 15.3+/-1.7 W/kg corresponding to an optimal velocity of 115+/-8.6 rpm. For the force-velocity test NonisoWpeak (the highest power obtained at any time during the test) was 14.4+/-1.9 W/kg and was achieved at a pedalling rate of 127+/-14 rpm. IsoWpeak was significantly higher than NonisoWpeak (p<0.001) but there were no significant differences between NonisoWpeak and IsoWmax (maximal mean power for each full crank revolution) for the revolutions from 90 rpm to 140 rpm. Though, NonisoWpeak and IsoWpeak are significantly different, there was a strong relationship between NonisoWpeak and IsoWpeak (r = 0.7158, p<0.001). There was also a strong relationship between NonisoWpeak and IsoWmax for the revolutions from 50 rpm to 120 rpm (p<0.001) and at 130 rpm (p<0.01).

Adult↗

PubMed2000

Time course of learning to produce maximum cycling power.

The purpose of this investigation was to determine the time course and magnitude of learning effects associated with repeated maximum cycling power tests and to determine if cycle-trained men exhibit different learning effects than active men who are not cycle-trained. Cycle-trained (N = 13) and active men (N = 35) performed short maximal cycling bouts 4 times per day for 4 consecutive days. Inertial load cycle ergometry was used to measure maximum power and pedaling rate at maximum power. Maximum power of the cycle-trained men did not differ across days or bouts. Maximum power of the active men increased 7 % within the first day and 7 % from the mean of day one to day three. Pedaling rate at maximum power did not differ across days or bouts in either the cycle-trained or active men. These results demonstrate that valid and reliable results for maximum cycling power can be obtained from cycle-trained men in a single day, whereas active men require at least 2 days of practice in order to produce valid and reliable values.

Adult↗

PubMed1998

The critical power function is dependent on the duration of the predictive exercise tests chosen.

The linear relationship between work accomplished (W(lim)) and time to exhaustion (t(lim)) can be described by the equation: W(lim) = a + CP x t(lim). Critical power (CP) is the slope of this line and is thought to represent a maximum rate of ATP synthesis without exhaustion, presumably an inherent characteristic of the aerobic energy system. The present investigation determined whether the choice of predictive tests would elicit significant differences in the estimated CP. Ten female physical education students completed, in random order and on consecutive days, five all-out predictive tests at preselected constant-power outputs. Predictive tests were performed on an electrically-braked cycle ergometer and power loadings were individually chosen so as to induce fatigue within approximately 1-10 mins. CP was derived by fitting the linear W(lim)-t(lim) regression and calculated three ways: 1) using the first, third and fifth W(lim)-t(lim) coordinates (I135), 2) using coordinates from the three highest power outputs (I123; mean t(lim) = 68-193 s) and 3) using coordinates from the lowest power outputs (I345; mean t(lim) = 193-485 s). Repeated measures ANOVA revealed that CPI123 (201.0+/-37.9W) > CPI135 (176.1+/-27.6W) > CPI345 (164.0+/-22.8W) (P<0.05). When the three sets of data were used to fit the hyperbolic Power-t(lim) regression, statistically significant differences between each CP were also found (P<0.05). The shorter the predictive trials, the greater the slope of the W(lim)-t(lim) regression; possibly because of the greater influence of 'aerobic inertia' on these trials. This may explain why CP has failed to represent a maximal, sustainable work rate. The present findings suggest that if CP is to represent the highest power output that an individual can maintain "for a very long time without fatigue" then CP should be calculated over a range of predictive tests in which the influence of aerobic inertia is minimised.

Adenosine Triphosphate↗

PubMed1996

Sport-seasonal changes in body composition, growth, power and strength of adolescent wrestlers.

Changes in body composition, somatic growth, power and strength of high school wrestlers (W, n = 8, 15.9 +/- 0.3 yrs) and controls (C, n = 6, 16.1 +/- 0.2 yrs) were studied early, mid-, late-, and 3.5-months post-season. Elbow flexion peak power (FPP), peak torque (FPT), extension peak power (EPP), and peak torque (EPT) were measured on an isokinetic dynamometer. C demonstrated normal rates of somatic growth and gains in strength and power. However, for W, significant (p < 0.05) decreases were found in: weight (WT, 61.6 +/- 2.8 to 59.2 +/- 2.8 kg), relative fat (%BF) (7.8 +/- 0.7 to 6.1 +/- 0.7 %), FPT (33.3 +/- 2.3 to 29.9 +/- 2.7 Nm), FPP (125.8 +/- 0.3 to 107.8 +/- 8.4 W), EPT (37.5 +/- 2.5 to 36.2 +/- 3.8 Nm), and EPP (132.7 +/- 8.4 to 126.7 +/- 12.3 W), between early-season and late-season and significant increases in WT (5.4 +/- 0.4 kg), fat-free mass (FFM, 4.4 +/- 0.7 kg), FPT (9.4 +/- 1.7 Nm), FPP (38.8 +/- 8.8 W), EPT (6.5 +/- 1.0 Nm), and EPP (24.4 +/- 4.7 W), between late-season and post-season. Compared to C, W had significantly (p < 0.05) smaller increases in mid-arm girth and flexed mid-arm cross-sectional muscle area (X-SECT) during the wrestling season and larger increases in shoulder girth, abdominal girth, and mid-arm girth, X-SECT, and biacromial, biilium, and anterior-posterior chest breadths during the post-season. Power and strength measures were significantly correlated with FFM, lean upper limb volume (ULV), and X-SECT (r = 0.74 to 0.93, p <0.0001). When covaried for FFM, ULV or X-SECT seasonal declines in strength and power were no longer significant while post-seasonal increases remained. In conclusion, pre- to late- season W demonstrated a lack of lean tissue accretion and reductions in strength. At post-season these variables returned to, or were above, pre-season levels. Results of analysis of covariance indicated that lean tissue changes were associated with the changes in strength and power.

Adolescent↗

PubMed1985

Specificity of aerobic and anaerobic work capacities and powers.

Thirty-three untrained subjects of both sexes, 18-31 years of age, performed several tests on cycle ergometers. Maximal aerobic power (MAP) was obtained in a progressive work test. Maximal aerobic capacity (MAC) was measured in a 90-min maximal test and was computed as the total work output during that period. Two all-out cycle ergometer work tests lasting 10 s and 90 s were used to estimate the anaerobic alactic capacity (AAC) and lactic capacity (ALC). Anaerobic alactic power (AAP) was computed as the highest output in 1 s in the AAC test and anaerobic lactic power (ALP) was obtained as the mean output during the last 5 s in an all-out test of 30 s. Correlation coefficients were computed between all measurements of capacity and power expressed per kg of body weight as well as with scores adjusted for sex differences. Common variances (r2 X 100) between measurements of power were either low (MAP-AAP, 40%) or moderate (MAP-ALP, 61%; AAP-ALP, 62%) while common variances between measurements of capacity were sometimes low (MAC-AAC, 49%) or higher (MAC-ALC, 76%; AAC-ALC, 77%). The common variances between tests of power and capacity reached high values when calculated with metabolic criteria of the same class (MAP-MAC, 81%; AAP-AAC, 92%). These results provide quantitative evidence to support the notion of specificity between the aerobic and the anaerobic work performances and support the distinction between capacity and power of the three energy systems.

Adenosine Triphosphate↗

PubMed2002

Accuracy of a narrow-diameter battery-powered endoscope in sedated and unsedated patients.

BACKGROUND: Esophagoscopy with a portable battery-powered endoscope could provide a safe, inexpensive, and minimally invasive way to screen for Barrett's esophagus or esophageal varices. The use of such an instrument in an unsedated fashion has not been previously evaluated. METHODS: Patients referred for an EGD were recruited to undergo an additional examination with the battery-powered endoscope before EGD. In phase 1, (n = 42) patients received conscious sedation before the battery-powered endoscopic examination. In phase 2, (n = 56) patients were not sedated and were given the option of a peroral (n = 43) or transnasal (n = 13) endoscopy. Examiners were blinded to patient history and procedure indications. Esophageal findings, ease of intubation, optical quality, and patient comfort for the battery-powered endoscope and standard EGD were recorded by the endoscopist. RESULTS: Ninety-eight patients (60 men, 38 women, mean age 53 years) were recruited. The sensitivity for detecting Barrett's esophagus, esophageal tumors, and esophageal varices was 54.5%, 66.7%, and 80%, respectively. Ease of intubation and patient comfort as perceived by the endoscopist were not significantly different between the battery-powered endoscope and EGD. Optical quality was ranked as less than 4 (on a 5-point scale with 5 = standard EGD and 1 = poor) in 42% of battery-powered endoscopic examinations. There were no complications. CONCLUSION: The accuracy of esophageal examination with a 3.1-mm endoscope is substantially inferior to standard EGD. Thus, the battery-powered endoscope would not be useful for screening patients for Barrett's esophagus or varices unless improvements in optical quality and visualization are made.

Adult↗