Trauma pneumonectomy revisited: the role of simultaneously stapled pneumonectomy.

OBJECTIVE: The aim of this study was to compare simultaneously stapled pneumonectomy (SSP) with individual ligation (IND) as a method for performing urgent pneumonectomy (Py) for trauma. METHODS: Twelve patients who required Py were reviewed. SSP was performed in nine cases and IND in three cases. The two groups had statistically similar injury severity scores, presenting systolic blood pressures, and Trauma and Injury Severity Score derived probabilities of survival. An animal model of Py was developed, in which seven animals underwent SSP and seven underwent IND methods. Burst pressures of the pulmonary artery and bronchus were calculated after 14 days. RESULTS: There were no differences noted in survival rates between SSP (5 (56%)) and IND (1 (33%)), nor in incidence of bronchopleural fistula. The SSP group had a significantly shorter operative time compared with that of IND (88.9 +/- 14.3 minutes vs 213 +/- 57.8 minutes, respectively, p - 0.01). The animal study revealed no difference in burst pressures of the bronchus (SSP = 662.9 +/- 169.9 mm Hg vs. IND = 591.4 +/- 193.2 mm Hg, p = 0.752) or of the pulmonary artery (SSP = 554.3 +/- 195.1 mm Hg vs. IND = 477.7 +/- 247.5 mm Hg, p = 0.529). CONCLUSION: Survival after pulmonary injuries that require Py depends upon the rapidity of hilar control and of the procedures itself. Simultaneously stapled pneumonectomy is an effective and rapid method of dealing with such rare injuries.

Exposure-induced high-pass filtering of a volume by means of an absorption hologram recording technique.

High-pass filtering effects have long been noted during recording of Fourier-type holograms on a saturable medium [Collier et al., Optical Holography (Academic, New York, 1971), p. 405]. The origin of the filtering effect lies in recording an absorption hologram such that the diffraction efficiency of strong spatial frequencies is significantly reduced by the saturable nature of the film. A simple optical configuration is used to take advantage of this effect in order to reduce the depth-of-focus noise associated with particle holography. The origin of the noise is clutter produced by a field of out-of-focus particles in which the particle under scrutiny exists [Reynolds et al., The New Physical Optics Notebook: Tutorials in Fourier Optics(Society of Photo-Optical Instrumentation Engineers, Belling-ham, Washington, 1989), p. 2054. A theoretical basis for the filtering is presented. Experimental results are shown.

Variable-cavity-length mode-locked Nd:YAG laser for noncontact generation and spectral control of narrow-band ultrasound.

A passively mode-locked, flash-lamp-pumped long-cavity Nd:YAG laser was developed with a cavity length that was variable in discrete increments from approximately 11 to 60 m, permitting adjustment of the mode-locked pulse repetition frequency over a range from 13 to 2.5 MHz. Multiple-pulse acoustic signals were generated with this laser in an aluminum sample and remotely detected by a path-stabilized Michelson interferometer. The energy in the multiple-pulse acoustic signal was confined to a considerably reduced spectral range compared with that in a single pulse. Successful laser generation of spectrally selective narrow-band ultrasound presents new opportunities to integrate advanced signal-processing strategies with interferometric detection to enhance the sensitivity of laser ultrasonics for industrial applications.

The Social Security Administration's 10-percent sample file of OASDI beneficiaries.

This is another in a series of technical articles describing Social Security Administration sample files and statistical systems. The focus of this article is the 10-percent sample file that provides program and demographic information on Social Security beneficiaries under the Old-Age, Survivors, and Disability Insurance program. The article explains the contents and availability of the 10-percent sample and presents several statistical tabulations as examples of the wide variety of data that can be developed from the file.

Full-field vibrometry using a Fabry-Perot étalon interferometer.

A solid lithium niobate Fabry-Perot étalon interferometer has been investigated with regard to its potential to perform full-field vibrometry. Predictions of theoretical system sensitivity were made based on signal-to-noise calculations. Optimized equations governing the étalon behavior were developed and examined in light of experimental results. The ability of the étalon system to accomplish multiple- (two-)-point simultaneous detection and full-field scanned vibrometry was demonstrated experimentally as well. The possibility of future work to obtain a snapshot image of an ultrasonic wave front is discussed.

System for high-speed time-resolved holography of transient events.

A configuration for sequential holographic recording based on a new system for obtaining a train of spatially separated light pulses at frequencies ranging from 6 to 35 MHz has been developed. The multipulse system uses a high-energy Q-switched Nd:YAG laser as a light source and incorporates a phase-front-preserving optical delay line and a specially graded beam splitter to produce as many as ten spatially separated light pulses of nearly equal energy. The temporal spacing between successive output pulses may be varied discretely in increments of 28.3 ns from 28.3 to 169.8 ns. The system is currently used for high-speed time-resolved holography of dynamic events with lifetimes between 100 ns and 1.5 micros. Other applications include using the system either as a single point or sequential-array source for laser generation of ultrasound.

Dual-beam interferometer for the accurate determination of surface-wave velocity.

A novel dual-beam interferometer has been designed and constructed that enables two beams from a He-Ne laser to probe remotely the surface of a material. The separation of the two He-Ne beams is adjustable in the 15-to- 40-mm range with a spatial resolution of 2 microm. Surface-acoustic-wave measurements have been performed with two different probe separations so that the travel time for the surface waves over a known distance can be determined accurately. With the aid of autocorrelation algorithms, the Rayleigh pulse velocity on 7075-T651 aluminum has been measured to be 2888 +/- 4 m/s. The current precision of the system is limited mainly by the 10-ns sampling rate of the digital oscilloscope used. Rayleigh pulse interactions with a surface-breaking slot, machined to a nominal depth of 0.5 mm, have also been examined and the depth estimated ultrasonically to be 0.49 +/- 0.02 mm. The system may also provide a technique for direct quantitative studies of surface-wave attenuation.

A preliminary durability study of two types of low-profile pericardial bioprosthetic valves through the use of accelerated fatigue testing and flow characterization.

Bioprosthetic heart valves are being used more often because of certain advantages they have over artificial valves. The bioprostheses are less thrombogenic, cause a lower incidence of hemolysis, and usually fail in a slow progressive manner. A combination of flow characterization and accelerated testing was used to assess the durability of two types of pericardial valves, the Ionescu-Shiley Low Profile Mitral and the Carpentier-Edwards Low Profile Aortic valve. The flow characterization work was done in an aortic chamber designed for in vivo simulation. The function of the valve was monitored between different stages of the accelerated testing using laser Doppler anemometry. Accelerated testing was performed at 1300 cardiac cycles per minute, and physiologic conditions both in closing pressures and the ambient temperature were maintained. Results indicated a change in flow characteristics owing to cyclic loading of the leaflet tissue. The flow orifice increased over time leading to a decrease in peak velocity. Future developments in Doppler ultrasound may facilitate non-invasive assessment of these peak velocity variations. Calcification of the tissue was not considered, since this was an in vitro study.

Absolute and random error analysis of the dynamic imaging microellipsometry technique.

A summary of the rapid high resolution full field ellipsometric imaging technique termed dynamic imaging microellipsometry is presented. The theoretical basis of a linear sensitivity coefficient approach to the coupling of individual error sources to ellipsometric absolute error is derived. Numerically computed sensitivity coefficient maps are presented with a discussion of their application to ellipsometric data calibration. An analysis of random error is presented and verified using comparisons between the theoretical estimations and system measurements.

Holographic velocimetry: an alternative approach for flow characterization of prosthetic heart valves.

In vitro techniques for evaluating circulation through prosthetic heart valves can yield important information concerning valve performance prior to implantation. Laser Doppler velocimetry is the most widely accepted noninvasive flow measurement technique, however, its use is somewhat limited for flow mapping applications. Holographic velocimetry is an alternative noninvasive in vitro approach for flow diagnostics. The advantage of this technique is the ability to do instantaneous full volume measurements for complete three-dimensional flow mapping at any instant in a flow cycle. Holographic velocimetry was used for the evaluation of circulation through a ball and cage valve. Results indicate that just beyond the apex of the cage very low velocity exists in the mean flow direction, while the other two components of velocity are rather large. Studies done further downstream from the valve begin to show the flow characteristics returning to the state of fully developed turbulent flow, as was previously seen upstream from the valve housing.

Absolute calibration of interferometric systems for detection and measurement of surface acoustic waves.

A calibration method for interferometric systems is shown to produce a minimum wave amplitude to which these systems may be calibrated in the measurement of harmonic surface acoustic waves. The calibration limit is ~3 orders of magnitude larger than the theoretical detection limit. The method proposed allows experimental determination of the detection limit of these systems. The calibration of a fiber-optic heterodyne interferometer is demonstrated, and the experimentally derived detection limit for the interferometer is shown to be 5.5 x 10(-15) m for unity detection bandwidth. This limit is obtained for a mirrored specimen with 0.14 mW of laser power incident on the optical detector.

Dynamic imaging microellipsometry: theory, system design, and feasibility demonstration.

Dynamic imaging microellipsometry (DIM) is a new rapid full-field imaging technique for high spatial resolution studies of thin films. The DIM concept is based on radiometric polarizer, compensator, specimen, and analyzer ellipsometry combined with video and image processing techniques. The theoretical basis for this approach is developed using the Jones vector and matrix formalisms. Basic systems design is presented with error model predictions of ellipsometric accuracies better than 0.1 degrees for full-field Delta and psi images captured in a few seconds with spatial resolution under 10 microm. Initial feasibility tests have demonstrated interframe discriminations of 0.36 degrees for Delta and 0.082 degrees for psi.

Generation of ultrasound by repetitively Q-switching a pulsed Nd:YAG laser.

Repetitively Q-switching a Nd:YAG laser during a single flashlamp pulse has been used successfully to generate a train of acoustic pulses with a repetition rate as high as 53 kHz. The spectral content of this multiple-pulse ultrasonic signal is significantly narrower in bandwidth than that of a single pulse. A corresponding reduction in the detection system bandwidth results in a marked improvement in detection sensitivity.

Signal-to-noise ratio analysis of one- and two-channel halfwave plate polarimeters.

The theoretical shot-noise-limited signal-to-noise ratio (SNR) is compared for one- and two-channel halfwave plate polarimeters, where rotation of the halfwave plate within the system causes a corresponding rotation in the incident linear polarization. This analysis estimates the smallest possible waveplate rotation that may be resolved by each polarimeter. It is shown that, at least theoretically, the differentially amplified two-channel polarimeter provides a superior SNR and thus correspondingly greater angular resolution. The degradation of the SNR as a result of polarization imperfections that might be introduced by less than ideal optical components is also considered.

Metabolism of coronary vasculature in euthyroid, hyperthyroid and recovering hyperthyroid rats: a histochemical study.

Coronary arteries and arterioles from normal rats, from rats made hyperthyroid by administration of desiccated thyroid for 10 weeks, and from hyperthyroid rats which were then fed normal control diets for 10 weeks, were examined histochemically to determine the activity of key metabolic pathways. The primary aims of this study were to determine if the alterations in particular enzyme and substrate activities that occur in thyrotoxic rat myocardium, arteries and arterioles were reversible and would return to normal levels following cessation of the hyperthyroid state. Our results suggest that hyperthyroid rats, even after 10 weeks on the normal diet, still show some compromise in arteriolar aerobic metabolism in favor of anaerobic pathways, while coronary arteries still demonstrate little glucose-6-phosphate dehydrogenase activity. Myocardial metabolic activity approximates that of normal control animals by the end of the 10th week on the normal diet.

A Histochemical study of the coronary vasculature in euthyroid and hyperthyroid rats.

Coronary arteries and arterioles in the left and right ventricles from normal and hyperthyroid rats were examined histochemically to determine and to compare their metabolic activities. The test animals were made hyperthyroid by administration of desiccated thyroid for 8-10 weeks. Using histochemical techniques, selected enzymes and components of key metabolic pathways were examined. These pathways included an evaluation of aerobic (oxidative phosphorylation, Kreb's cycle and respiratory chain) and anaerobic metabolic capacity, hexose-monophosphate shunt activity, amounts of deoxyribonucleic and ribonucleic acids present and activity of beta-oxidation of fatty acids. Our results indicate that normal coronary arteriolar metabolism is predominantly aerobic. The findings also suggest a reduction in aerobic metabolism with an accompanying increase in anaerobic potential in the hyperthyroid coronary arterioles. Thus, during thyrotoxicosis, the coronary arterioles may partially shift from aerobic to anaerobic metabolism. Moreover, in both the normal and thyrotoxic rat heart, the coronary microvasculature appears quite stable with little cell proliferation. In contrast, both the control and hyperthyroid rat coronary arteries appear to utilize primarily anaerobic pathways, while the control and hyperthyroid myocardium seem highly dependent upon aerobic metabolism. The tremendous reduction in glucose-6-phosphate dehydrogenase activity in hyperthyroid, when compared to normal coronary arteries and some larger arterioles, implies a reduced capacity for nucleic acid and protein synthesis in the test animals.