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At least 469 records · Page 26Linked to original sources

PubMed1997

Sonography of acute cholecystitis: comparison of color and power Doppler sonography in detecting a hypervascularized gallbladder wall.

OBJECTIVE: We evaluated the sensitivity and specificity of power Doppler sonography compared with conventional color Doppler sonography and gray-scale sonography in diagnosing patients with acute cholecystitis. SUBJECTS AND METHODS: Seventy-six patients with right upper quadrant pain and 72 healthy volunteers underwent gray-scale sonography, conventional color Doppler sonography, and power Doppler sonography of the gallbladder. The vascularity of the gallbladder wall was scored on a scale of 0 to +3. Histology revealed acute cholecystitis in 55 patients. Histologic specimens and clinical workups showed that the remaining 21 patients suffered from other diseases. RESULTS: Sensitive sonographic features such as the positive Murphy's sign (in 96% of patients with acute cholecystitis), calculi (95%), and a thickened gallbladder wall (73%) lacked specificity (71%, 38%, 67%, respectively) for diagnosing acute cholecystitis. In our study, the sensitivity of power Doppler sonography was 95% compared with 33% for color Doppler sonography in revealing a hypervascularized gallbladder wall. Power Doppler sonography revealed hyperemia within a nonthickened gallbladder wall in four patients with surgically proven acute cholecystitis. Specificity of power Doppler sonography was 86% compared with 95% for conventional color Doppler sonography. False-positive results with power Doppler sonography were caused by pancreatitis, duodenal ulcer, and gallbladder carcinoma. Interobserver variability seemed to play no significant role. No intramural hypervascularity was detected in the volunteer group. In four (4%) of 89 symptomatic patients we could not use power Doppler sonography because of the patients noncompliance. Mean values of the resistive index assessed within intramural vessels of the gallbladder showed no significant differences (p < .001) between patients with acute cholecystitis (0.73) and patients with other diseases (0.71). CONCLUSIONS: Although the sensitivity of power Doppler sonography in diagnosing acute cholecystitis was similar to that of gray-scale sonography, the specificity of power Doppler sonography was significantly higher, which may substantially improve diagnostic confidence. However, the high susceptibility of power Doppler sonography to motion artifacts makes appropriate adjustment of technical parameters much more relevant than with other sonographic imaging. The resistive index within intramural vessels has no clinical use in the diagnosis of acute cholecystitis.

Acute Disease↗

PubMed2001

Effects of changes in power setting of an ultrasonic aspirator on amount of damage to the cerebral cortex of healthy dogs.

OBJECTIVE: To determine the minimal ultrasonic aspirator pressure necessary to damage the cerebral cortex of healthy dogs. ANIMALS: 9 mixed-breed dogs. PROCEDURE: The study comprised 2 parts. In part A, 6 dogs were euthanatized immediately prior to the experiment. In part B, 3 dogs were anesthetized for recording of physiologic variables. In both parts, craniectomy and durotomy were performed to bilaterally expose the lateral aspect of the cerebral cortex. An ultrasonic aspirator was placed in contact with various areas of the cerebral cortex, and aspirator power was altered (10, 20, 30, and 40%). Duration of contact at each power was 5 and 10 seconds. Subsequently, gross morphologic and histologic damage was assessed in the cortex. RESULTS: Gross observations for all dogs were similar. At 10% power, visible or histologic damage was not evident in the cortex. At 20% power, the cortex was slightly indented from contact with the hand piece; however, cortical disruption was not evident. Cortical disruption was initially detectable at 30% power in some dogs and was consistently evident at 40% power in both sets of dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonic aspirator power of < 20% created minimal acute morphologic damage to the cortex. Power settings between 20 and 30% may superficially damage the cerebral cortex in healthy dogs, whereas 40% power consistently damages the cerebral cortex. Knowledge of the degree of damage to cerebral cortex caused by various amounts of power for ultrasonic aspirators will allow surgeons to avoid damaging normal brain tissues during surgery.

Animals↗

PubMedDate not supplied

Potential for power deposition conformability using reflected-scanned planar ultrasound.

Specialized heating devices for the simultaneous delivery of hyperthermia and ionizing radiation are being developed by several investigators in an effort to increase thermal radiosensitization in clinical treatment. One particular device is the SURLAS (Scanning Ultrasound Refléctor-Linear Array System), which was designed specifically to operate concomitantly with medical linear accelerators. The technical feasibility of the SURLAS has been demonstrated, and a design optimization study has been performed. The main objective of this paper is to demonstrate the potential for power deposition conformability of the SURLAS. This has been done using a thermographic technique which provides qualitative, high spatial-resolution measurements of power deposition distributions. The technique consists of normally insonating one surface of a 1 cm layer of a Polyurethane phantom while the temperature field on the opposite air-exposed surface is recorded using an infrared camera during the first few minutes after power insult. The thermal fields measured in this way are good qualitative estimates of relative power deposition. To demonstrate conformability, a region of 10 cm (the length of the array) by 12 cm (the scanning distance) on the air-exposed phantom surface was divided into 24 sectors (24 subregions with independent power control). Each sector was 2.5 x 2 cm across and long the scanning direction respectively. Several sector insonation patterns were synthesized in an open-loop fashion by properly adjusting power levels to each of the elements of an array as a function of reflector position as the reflector was scanned continuously in a reciprocating fashion at a constant speed. The array was made of a single piezoelectric crystal with resonant frequency of 2.2 MHz and electrically segmented into four 2.5 x 2.5 cm elements. The reflector was made of a 0.5 mm thick Brass plate. Sufficient power was supplied to the array to induce peak temperature elevations of about 10 degrees C in 60s at a scanning speed of 2.4 cm/s. The results show that measured relative power deposition patterns agreed well with programmed insonation patterns demonstrating that the SURLAS possesses great potential for power conformability, and thus, for temperature feedback power deposition control.

Humans↗

PubMedDate not supplied

A new method of calculating intraocular lens power after photorefractive keratectomy.

PURPOSE: To find a method of calculating intraocular lens (IOL) power that may be independent of preoperative data, in eyes that have developed a cataract after refractive surgery. METHODS: Prior to and 1 month after PRK, the SRK/T formula was used to calculate IOL power in 88 eyes of 65 patients with a preoperative spherical equivalent refraction between -16.25 to +0.25 D (mean -5.39 +/- 3.19 D). IOL power was calculated by utilizing the spherical equivalent refraction as target both before and after PRK. Utilizing the postoperative corneal radius measurement (R2), an underestimation of the IOL power was found. For this reason, the mean postoperative corneal radius (R3) that gave the same IOL power found before surgery was calculated for each patient. The R3/R2 ratios were plotted against the axial eye length and a linear regression formula was used to calculate R2 correcting factors that gave the new corneal radius (R4). Patients were divided into classes according to axial eye length, and the mean R3/R2 ratios for each class were calculated and used to recalculate the new mean radius (R5). IOL power for emmetropia was calculated in all patients by utilization of R3, R4, R5, the historical method, and the "true corneal power" method. RESULTS: Within +/-0.50 D from the IOL power calculated with R3, R4 gave 35 (39.3%) IOLs, while R5 gave 40 (45.5%) IOLs; the clinical history method gave 24 (27.3%) IOLs and "true corneal power" gave 23 (26.1%) IOLs, with a statistically significant difference P<.001). CONCLUSIONS: Our theoretical method, based on correlation between axial eye length and corneal radius correcting factors, may represent an effective method of calculating IOL power after PRK, especially if the history of the patient is unknown.

Adult↗

PubMedDate not supplied

New formula to calculate corneal power after refractive surgery.

PURPOSE: To assess the validity of intraocular lens (IOL) power calculations utilizing a theoretical variable refractive index correlated to axial length after myopic photorefractive keratectomy (PRK) in a clinical simulation and in patients who underwent cataract surgery after PRK for myopia. METHODS: Our study included 374 eyes of 300 patients who had PRK for myopia (-2.00 to -12.00 D, mean -4.83 +/- 2.57 D), divided into three groups: Group I had 44 eyes with small ablation zones of 5 to 5.5 mm; Group II had 49 eyes with large ablation zones of 6 to 7 mm; Group III was the control group of 281 eyes (201 patients; 87 males and 114 females) with small and large ablation zones. PRK was performed using the Aesculap-Meditec MEL 60/94 and MEL 70 lasers, and the corneal power was acquired by corneal topography (EyeSys 2000) and a Nidek KM-800 keratometer. RESULTS: There was a higher correlation between corneal power and both the change in refraction and axial length when calculated using keratometric measurements. IOL power calculated using keratometric postoperative PRK power was underestimated. The difference between the mean calculated and actual IOL power for emmetropia was 4.30 +/- 2.34 D. A theoretical variable refractive index (obtained from eyes treated with large PRK ablation zones) that correlated with axial length provided the correct keratometric postoperative PRK power: difference between mean calculated and mean actual IOL power was 0.42 +/- 1.23 D. CONCLUSIONS: We propose a theoretical variable refractive index that is correlated to axial length. Utilizing this keratometric correct power, we calculated IOL power similar to that for emmetropia.

Adult↗

PubMed2004

Contrast-enhanced power Doppler sonography in breast lesions: effect on differential diagnosis after mammography and gray scale sonography.

OBJECTIVE: To evaluate the efficacy of contrast-enhanced power Doppler sonography in the differential diagnosis of breast lesions after a mammography-gray scale sonography combination. METHODS: Sixty-eight patients with 69 breast masses underwent power Doppler sonography before and after intravenous injection of a contrast agent. The lesions were diagnosed as "highly suggestive of malignancy" (category 5; n = 32), "suspicious" (category 4; n = 21), and "probably benign" (category 3; n = 16) by mammography and gray scale sonography, modeled on the American College of Radiology Breast Imaging Reporting and Data System classification. Power Doppler findings did not affect patient treatment. The authors subjectively evaluated the estimated area of vascularity, degree of enhancement following contrast agent administration, morphologic features, and distribution of vessels within the lesions. RESULTS: The final diagnoses were malignant in 28 lesions and benign in 41. Significant enhancement after contrast agent injection was detected in both the malignant and benign groups. Only 2 criteria, estimated area of vascularity and degree of enhancement following contrast agent administration, proved to be significant diagnostic determinants for contrast-enhanced power Doppler sonography (P < .001; interobserver agreements, 74.4 and 77.8, respectively). Contrast-enhanced power Doppler sonography provided a higher specificity, positive predictive value, and negative predictive value than power Doppler sonography but a lower sensitivity and negative predictive value than mammography-gray scale sonography. Only in the category 4 lesions could the combination of mammography-gray scale sonography and contrast-enhanced power Doppler sonography accomplish a higher specificity (71%) and positive predictive value (70%) than mammography-gray scale sonography (39% and 53%, respectively). CONCLUSIONS: Power Doppler and contrast-enhanced power Doppler sonography cannot be recommended as confirmatory tests in Breast Imaging Reporting and Data System category 3 and category 5 lesions. Although contrast-enhanced power Doppler sonography may help reduce unnecessary biopsies in Breast Imaging Reporting and Data System category 4 lesions, recommendation of its use has many drawbacks, such as imperfectly established criteria, lack of absolute certainty, and high cost.

Adult↗

PubMed2001

The load that maximizes the average mechanical power output during explosive bench press throws in highly trained athletes.

The power output generated with different barbell loads and which resistance generated the maximum mechanical power output (Pmax) during explosive bench press-type throws (BT) in a smith machine device were investigated in power-trained athletes. Thirty-one rugby league players were tested for 1 repetition maximum (1RM) free-weight bench press strength (1RM BP). Maximal power output was assessed by the Plyometric Power System during BT using resistances of 40, 50, 60, 70, and 80 kg (BT P40, BT P50, BT P60, BT P70, and BT P80). It was found that BT Pmax occurred with resistance of 70.1 +/- 7.9 kg, representing 55 +/- 5.3% of 1RM BP of 129.7 +/- 14.3 kg. The power output with all loads except the BT P70 were different from the BT Pmax. The BT P70 and BT P80 were not different from each other. Furthermore, the BT P60 and BT P80 were not different from each other. This suggests that although resistances of 55% 1RM BP may maximize power output during explosive BT, loads in the range of 46-62% also allow for high power outputs. Resistances of 31-45% of 1RM BP resulted in significantly lower power outputs. Compared with previous research of BT in strength-trained athletes, the results of this investigation suggest that power-trained athletes may generate their Pmax at higher percentages of 1RM.

Adult↗

PubMed2001

[Parameters of power spectral analysis of heart rate variability for use in clinical evaluation of various stages of diabetic cardiovascular autonomic neuropathy].

UNLABELLED: The aim of the study was to select parameters of power spectral analysis appropriate for clinical evaluation of various degrees of diabetic cardiovascular autonomic neuropathy. The diagnosis of autonomic neuropathy was based on Ewing's battery of cardiovascular autonomic function tests and on short-term power spectral analysis of heart rate variability during a modified orthostatic load (in positions supine-standing-supine). 52 diabetic patients and 24 age-matched controls were included. Diabetic patients were divided into two groups according to the total Ewing score. Groups of 14 subjects with early autonomic neuropathy and 38 subjects with severe AN were comparable in age and diabetes duration. RESULTS: Cumulative spectral power of the total frequency band in all three positions (Total Power LFHF 1 + 2 + 3) proved to be the most selective and discriminating parameter of power spectral analysis between the control group and diabetic patients with severe autonomic neuropathy in stepwise discriminant analysis. Spectral power of low-frequency band in positions 1 + 2 + 3 (Power LF 1 + 2 + 3) proved to be the most selective and discriminating parameter between diabetic groups with early and severe autonomic neuropathy. CONCLUSION: The most discriminating parameters of power spectral analysis of heart rate variability for the determination of autonomic function seem to be Total Power LFHF 1 + 2 + 3 and Power LF 1 + 2 + 3.

Adult↗

PubMed2002

Anaerobic power performance of incumbent female firefighters.

Prior studies have indicated that anaerobic power tests correlate highly with firefighting performance tasks. This investigation measured peak power and mean power of 10 incumbent female firefighters (age, 29.8 +/- 2.1 years; height, 169.7 +/- 7.9 cm; weight, 66.8 +/- 9.9 kg) who underwent a 30-second Wingate anaerobic power test. Peak power and mean power were recorded as 451.6 +/- 69.6 W and 314.1 +/- 32.7 W, respectively, compared with a control group. Results revealed that incumbent female firefighters did not score significantly greater than the control group in either peak power or mean power. Although the level of anaerobic power needed to perform firefighting tasks is unknown at this time, it does not appear that incumbent female firefighters are reliant on anaerobic power as operationalized in this study.

Adult↗

PubMed2002

The relative effectiveness of six powered toothbrushes for dental plaque removal.

During the past three years, a number of new powered toothbrushes have been marketed in the United States. The objective of this study was to compare the single-use plaque removal efficacy of six powered toothbrushes: a new prototype (Crest SpinBrush Pro), Crest SpinBrush, Oral-B Battery, Colgate Motion, Oral-B 3-D Excel, and a Crest experimental toothbrush design. This study was a randomized, controlled, examiner-blind, six-period crossover design, which examined plaque removal with six powered toothbrushes following a single use in 26 subjects. Plaque was scored before and after brushing for one minute using the Turesky, et al. Modification of the Quigley-Hein Index. For statistical comparison, the plaque scores were averaged on a per-subject basis. Each subject had a single whole-mouth average score for baseline and for the exam following a one-minute brushing with their assigned toothbrush. The difference (baseline minus post-brushing) in average scores was calculated and analyzed using an analysis of covariance for a crossover design, with baseline whole-mouth average score as the covariate, and terms in the model for subjects, periods, and treatments. Mean baseline plaque scores ranged from 1.770-1.897 for the six toothbrush treatment groups and were not statistically significantly different. Using the analysis of covariance, with respect to all surfaces examined, the new prototype powered toothbrush (Crest SpinBrush Pro) delivered an adjusted mean difference between baseline and post-brushing plaque scores of 0.544, while the five remaining powered toothbrushes delivered an adjusted mean difference of 0.470-0.497. These results represent 10-16% greater plaque removal for the new prototype powered toothbrush. Overall, the six toothbrushes were not statistically significantly different (p = 0.199). However, results of unadjusted pair-wise comparisons conducted per the study protocol found that the new prototype powered toothbrush removed greater levels of plaque than the Oral-B 3-D Excel, Colgate Motion, and Crest experimental toothbrush (p = 0.028, p = 0.038, and p = 0.028, respectively). With respect to buccal and lingual surfaces, the new prototype powered toothbrush (Crest SpinBrush Pro) delivered very similar results relative to the control toothbrushes. Collectively, the results suggest that the new prototype powered toothbrush may offer enhanced plaque removal efficiency relative to the five other toothbrushes, and be at least as good as the five tested powered toothbrushes.

Adolescent↗

PubMed2002

The relative cleaning effectiveness of manual and powered toothbrushes.

Recently, a number of new low-cost powered toothbrushes have been marketed globally. Assessment of their cleaning capability in vitro is now becoming manageable with novel configurations of new brushing machines, which allow for the conventional brushing action and added device action. In this study, the in vitro stain removal efficiency of two marketed powered toothbrushes (Crest SpinBrush and Dr. Best Battery), a new prototype (Crest SpinBrush Pro) and two manual toothbrushes (Oral-B Indicator Soft and Oral-B CrossAction) was evaluated using a different brushing technique as a modification of the laboratory testing method developed by Stookey and associates at Indiana University Oral Health Research Institute. This was a randomized, parallel-group design study that examined stain removal with a novel toothbrushing configuration adapted for powered and manual toothbrushes. Stain was scored before and after brushing for two consecutive one-minute periods using digital image analysis. The mean change in L* was statistically compared among toothbrushes with analysis of covariance. The mean baseline stain scores ranged from 36.3-40.2 for the five toothbrush treatment groups. There was statistically significant evidence of imbalance with respect to baseline mean L* (p = 0.006), ranging from 36.3 for the CrossAction brush to 40.2 for the Crest SpinBrush Pro. Baseline stain imbalance was addressed with the ANCOVA statistical model which adjusts for baseline L*, effectively comparing all treatments at the same baseline stain level. Baseline L* was not statistically significant (p > 0.1) in the ANCOVA model at one or two minutes. With respect to all surfaces examined, the new prototype powered toothbrush (Crest SpinBrush Pro) delivered an adjusted (via analysis of covariance) mean L* reduction of 14.4 and 22.0 at the end of the first and second brushing periods, respectively, while the four remaining toothbrushes delivered adjusted mean L* reductions ranging from 5.6-8.6 and 9.4-13.3 at the end of the first and second brushing periods, respectively. These results represent 67-157% for the first brushing period, and 65-134% for the second brushing period greater stain removal for the new prototype powered toothbrush. Overall, the new prototype powered toothbrush had statistically significantly greater stain removal (p < 0.001) than all other toothbrushes tested. The results, using this powered toothbrush-compatible brushing machine configuration, show that the new prototype powered toothbrush (Crest SpinBrush Pro) produced statistically significantly enhanced stain removal efficiency relative to the four other toothbrushes, including Crest SpinBrush and Dr. Best powered toothbrushes. The newly configured brushing machine delivered a robust method for separating statistically significant in vitro differences for the complex cleaning action of powered toothbrushes.

Analysis of Variance↗

PubMed2003

[Urodynamic fundamentals, flow curve and urethral echo-Doppler. (Calculation of the urination strength and spectral power].

OBJECTIVES: We present the calculation of two parameters of practical interest for the urologists, which help to understand bladder phenomena. They are the real (total) power developed during micturition, and the spectral power of the flow curve, considered this as a finite time discrete signal. METHODS: We use Doppler ultrasound to calculate the propelling power of the urine towards the exterior. The calculation of the spectral power is included among the auxiliary calculus methods employed for the calculation of the contractile power in those cases in which the flow curve has several humps; we could only calculate the real power in one of them because the Doppler only measured the speed in one curl. RESULTS: We report one case with several curls in the flow curve, in which we could only test speed in one of the curls. The calculation of the spectral power allows us to compare curls and to calculate the total power just by addition. CONCLUSIONS: These two power measures are the expression of the same phenomenon, but they are different, showing one the micturition process from the flow curve and the other one from bladder contraction. We believe it is interesting to know them as a useful work tool. In the same way, the usefulness of Doppler ultrasound to obtain the values of urine speed through the urethra is demonstrated, a necessary data for the calculation of the bladder contractile power.

Algorithms↗

PubMed2003

Three-dimensional power Doppler ultrasonography for demonstrating associated arteries of hepatocellular carcinoma.

BACKGROUND AND PURPOSE: Although 2-dimensional (2D) ultrasonography (US) with conventional color and power Doppler US has been applied widely in the differential diagnosis of hepatic tumors and in the follow-up of treatment of hepatocellular carcinomas (HCCs), it has limited capabilities for demonstrating associated arteries of HCCs. Three-dimensional (3D) US can provide more accurate depiction of stereotypic vascular patterns than 2D US. This study investigated the efficacy of 3D power Doppler US versus angiography for demonstrating associated arteries of HCCs. METHODS: A total of 24 HCCs with surrounding or intratumoral arteries detected by 2D power Doppler US were studied using a US machine equipped with power Doppler software and a built-in stereo image processing workstation. Serial 2D images were reconstructed into 3D images to analyze the distribution and routes of arteries associated with HCCs. These results were compared with angiographic findings. RESULTS: Three-dimensional US imaging of vasculature associated with HCCs in the 24 patients was categorized into 3 patterns: peripheral arteries around the tumor (pattern I, n = 9); no more than 4 intratumoral arteries with or without originating peripheral arteries (pattern II, n = 9); and prominent (more than 4) intratumoral arteries (pattern III, n = 6). Most feeding arteries shown in angiograms that could be demonstrated by 3D power Doppler US were in HCCs with pattern I and II vasculature. In HCCs with pattern III, the basket vascular pattern shown on angiograms could also be demonstrated on 3D power Doppler US. The vascular proficiency, including major feeding arteries and branches of feeding arteries,could be shown to significantly increase from pattern I to III on 3D power Doppler, but this method had a lower detection rate of smaller branches and neovascularization than angiographic study. CONCLUSION: Three-dimensional power Doppler US can effectively depict the associated arteries of HCCs, especially the major feeding arteries. Three vascularization patterns of HCCs were categorized in 3D images. There is a good correlation of the findings of 3D power Doppler US with angiographic study. These findings demonstrate the usefulness of 3D power Doppler as a non-invasive alternative to angiographic examination.

Adult↗

PubMed2002

Different estimates of cardiac power: relationship to altered loading conditions.

Peak instantaneous power is a prognostic index of LV function but is difficult to measure. It is relatively load independent when corrected by preload (EDV2). Easier to acquire power estimates have been proposed--including mean and simplified power. These require only echo Doppler flow and cuff pressures, but their relationship to invasively derived results has not been studied. Using a well-validated numerical model of the cardiovascular system, different estimates of power were compared for varying preload, afterload, and contractility. All power results were divided by EDV2. Estimates of power correlate with peak power over a wide range of physiology. Corrected power estimates were independent of preload and afterload, but predictably increased with contractility. Different estimates of preload corrected power can be derived from non-invasively obtained variables and correlate with corrected peak instantaneous power.

Algorithms↗

PubMed1990

[Effect on electroacupuncture on experimental epilepsy--power spectrum analysis of EEG].

The present study was undertaken to investigate the effect of electroacupuncture (EA) on electroconvulsive shock (ECS) and penicillin-induced convulsions in rats, using power spectrum analysis technique. Under quiet state, delta and theta bands were found to be predominant in the power spectrum of spontaneous EEG's with the peak of the main power in the delta band. During ECS and penicillin-induced convulsions, the power percentage of the delta band decreased, while those of alpha and beta bands increased. The bands with the peak of the main power shifted to the right, and the total power was distinctly enhanced. No marked change in background EEG activity was observed during EA stimulation. In the case of EA plus ECS or penicillin-induced convulsions, the power percentage of the delta band increased, while those of alpha and beta bands decreased. The peak of the main power returned to the delta band with a decreased total power. The compressed power spectrum array showed distinct suppression of convulsions by EA audio-visually. These results suggest that EA enables the EEG to synchronize and enhances the inhibitory process of the brain, thereby plays its anticonvulsant role.

Animals↗

PubMed1994

13CO2 isotopic laser used through the operating channel of laser laparoscopes: a comparative study of power and energy density losses.

OBJECTIVE: To evaluate the power transmission, spot size, power density, and energy density of a new isotopic carbon dioxide (13CO2) laser compared with a conventional CO2 laser. METHODS: Experiments were performed in a laboratory using a conventional CO2 laser and an isotopic 13CO2 laser. Two laparoscopes with 5-mm and 7.5-mm operating channels were connected to a standard coupler and to each of the lasers. Standardized measurements were made of power transmission and spot size using both nitrogen purge gas and CO2 purge gas at rates of 1-20 L/minute. Power density and energy density were calculated for continuous mode and ultrapulse mode transmission, respectively. RESULTS: The isotopic 13CO2 laser power transmission was higher and proportional to input power, while spot size was smaller compared with the conventional laser and was insensitive to power level or purge rate. Power density and energy density were markedly higher with the isotopic 13CO2 laser, reaching the threshold for complete ablation, and were much more predictable. The 7.5-mm operating channel generally had superior operating results compared with the 5-mm channel because of the smaller spot size and higher power transmission. CONCLUSIONS: The isotopic 13CO2 laser is associated with much higher power density and energy density capabilities than are conventional CO2 lasers. At surgery, we have noted less thermal injury, faster ablation, more precise and predictable tissue effects, and greater control of tissue effect with the isotopic 13CO2 laser than with other CO2 lasers. These results are attributed to the improved beam propagation through CO2 insufflation gas measured in the laboratory. Thermal injury can be varied according to the required surgical situation and can be kept to an absolute minimum at high-pulse energy.

Carbon Dioxide↗

PubMed1993

Perception of power among dietitians.

Power is a new concept in the field of nutrition that has increasing relevance for the survival of the profession in the 1990s. This study reports on dietitians' perception of power. A survey questionnaire was mailed to all members of the New Jersey State Dietetic Association (1,969 members). Usable responses were obtained from 521 dietitians (a response rate of 27%). The majority of respondents were female, married, and younger than 40 years of age; 37% were in clinical positions and 62% had completed internship and master's degree programs. Respondents rated power as very important (30%) or important (44%), and the terms accomplishments, control, intelligence, and connections were key descriptors of power. Power was felt to be acquired through knowledge, education, and position/title. The positions of department head, chief clinical dietitian, and nutrition support dietitian ranked in the middle of a power hierarchy. The top positions were chief executive officer and physician, and the bottom position was tray-line worker. Responses to "power" scenarios showed greater professional concern (60%) than personal concern (35%) over a clinical scenario (loss of control of the nutrition formulary) than a managerial scenario (threatened layoffs) (38% and 32%, respectively). Dietitians need to focus on and understand the concept and realistic use of power in the workplace. Initially, basic concepts and skills related to power must be incorporated into dietetics and continuing education using a gender-focused teaching approach.

Dietetics↗

PubMed2006

Ethics, a neglected dimension of power relationships of physician leaders.

OBJECTIVE: Physician leaders in obstetrics and gynecology find themselves in complex power relationships with administrative subordinates, administrative peers, and administrative superiors. The ethical dimensions of these power relationships have not been examined previously. STUDY DESIGN: The authors draw on the work of 3 major historic figures (John Gregory, Thomas Hobbes, and Friedrich Hoffmann) to identify for the first time 3 major types of power relationships and organizational cultures. Gregorian power relationships and organizational cultures are characterized by shared fiduciary responsibility that advances the core mission of a health care organization. Hobbesian power relationships and organizational cultures are characterized by relentless self-interest in a zero-sum game. Hoffmannian power relationships and organizational cultures are characterized by enlightened self-interest in a win-win game. RESULTS: The authors analyze the ethical dimensions of power relationships of physician leaders with subordinates, peers, and superiors and of organizational cultures. CONCLUSION: The authors support transformational leadership toward Gregorian power relationships and organizational cultures, using, when necessary, Hoffmannian power relationships and organizational cultures as a way station.

Administrative Personnel↗