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At least 271 records · Page 15Linked to original sources
PubMed1998

Assessment of bone density using ultrasonic backscatter.

The goal of this project was to investigate the utility of ultrasonic backscatter for the assessment of bone status. Ultrasound offers a low-cost, portable, nonionizing alternative or complement to common X-ray- or radioisotope (gamma ray)-based methods of bone densitometry. Ultrasonic backscatter may provide useful information not revealed by ultrasonic attenuation and sound-speed densitometers. Backscatter is sensitive to microstructural variations in acoustic impedance and should therefore provide information regarding architecture (which is related to fracture risk), as well as density. Ultrasonic backscatter at 2.25 MHz and CT bone densitometric data have been acquired from 10 healthy human volunteers. The degree of correlation between CT and ultrasonic backscatter is high (r = 0.87, p < 0.001). The envelope signal-to-noise ratio was 1.81 +/- 0.08 (mean +/- standard deviation). This suggests that the number of scatterers per resolution cell is large, the radiofrequency signal approximately obeys circular Gaussian statistics, and the envelope obeys Rayleigh statistics. These results indicate promise for ultrasonic backscatter as a substitute for or an adjunct to other ultrasonic measurements (attenuation and sound speed) and X-ray measurements for the assessment of bone status.

Adult↗
PubMed2003

Ultrasonication of chitosan and chitosan nanoparticles.

The objective of this study was to evaluate the effects of ultrasonication on chitosan molecules and nanoparticles. Molecular weight (M(v)) of chitosan HCl (M(v) 146 kDa and degree of deacetylation (DD) 96%) decreased linearly with increasing duration and amplitude of ultrasonication. DD and FTIR absorption were unaffected. X-ray diffraction (XRD) analysis suggested greater chain alignment in the ultrasonicated chitosan samples. Chitosan nanoparticles had mean diameter of 382 nm, polydispersity of 0.53 and zeta potential of 47 mV. Ultrasonication administered at increasing duration or amplitude decreased the mean diameter and polydispersity of the nanoparticles. Zeta potential and FTIR absorbance were unaffected, while XRD suggested a greater disarray of chain alignment in the nanoparticle matrix. Under the transmission electron microscope (TEM), freshly prepared nanoparticles were dense spherical structures which became fragmented after ultrasonication for 10 min at amplitude of 80. Untreated nanoparticle formulation turned turbid upon storage for 3 weeks at ambient conditions due to substantial swelling of the nanoparticles. Ultrasonicated nanoparticle formulation remained clear on storage. Although the particles had also swelled, they were no longer spherical, assuming instead an irregular shape with branching arms. In conclusion, high-intensity ultrasonication induced considerable damage on the chitosan nanoparticles which could affect their function as drug carriers.

Adjuvants, Pharmaceutic↗
PubMed1996

A comparison of bronchodilator responses to albuterol delivered by ultrasonic versus jet nebulization in moderate to severe asthma.

BACKGROUND: Nebulization of beta-agonists is preferred as a mode of treatment in moderate to severe asthma. Few studies, however, have compared its use in this population using an ultrasonic versus a jet nebulizer. OBJECTIVE: The purpose of the study was to compare bronchodilator responses to albuterol between an ultrasonic and a jet nebulizer in moderate to severe asthma. METHODS: Fifteen stable, moderately to severely asthmatic patients were randomized to receive the ultrasonic or jet nebulizer for 2 weeks. They were then crossed over for an additional 2 weeks. Albuterol was the agent used. The bronchodilator response was measured at baseline, and up to four hours after treatment with each nebulizer. Daily peak flows were then done for 2 weeks. RESULTS: The maximal percentage of increase in FEV1 at 30 minutes using the ultrasonic nebulizer was 39.9 +/- 8% (P < 0.001) versus 25.1 +/- 7.6% (P = .005) using the jet nebulizer. There were no other differences between the ultrasonic and the jet nebulizer in FEV1 or FVC during the 4-hour spirometry. During the home trial, the difference in evening PEFR between the jet nebulizer (69.05 +/- 14.9 L/min) and the ultrasonic nebulizer (90.11 +/- 18.7 L/min) was significant (P = .04). CONCLUSIONS: In summary, the ultrasonic and the jet nebulizer produced comparable bronchodilator responses to albuterol in stable moderately to severely asthmatic patients.

Adolescent↗
PubMed1997

Assessment of the strength of the proximal femur in vitro: relationship with ultrasonic measurements of the calcaneus.

Matched pairs of the right proximal femur and right calcaneus were obtained from 64 cadavers (28 female, 36 male). Ultrasonic velocity and broadband ultrasonic attenuation were measured in the calcaneus using a laboratory ultrasound system. Bone mineral density (BMD) was measured at the calcaneus and at the trochanteric and neck regions of the femur using dual-energy X-ray absorptiometry. Femoral strength was determined in a mechanical test simulating a fall onto the greater trochanter. Femoral BMD was more strongly correlated with femoral strength (r2 = 0.71, 0.88 for neck BMD and trochanteric BMD, respectively) than were any of the other predictive variables investigated (p < 0.05). Calcaneal ultrasonic measurements alone produced correlations with femoral strength of r2 = 0.40-0.47, with no significant differences observed in predictive ability between the various ultrasonic parameters. In multiple regression analysis, ultrasound was, in general, not a significant additional independent predictor of femoral strength when combined with either femoral or calcaneal BMD, and combining ultrasonic parameters did not improve the ability to predict femoral strength. Calcaneal width was found to be significantly correlated with both femoral strength and femoral BMD, and this explained the slightly better correlations with femoral strength found for those ultrasonic parameters which were not effectively normalized for calcaneal width. In summary, calcaneal ultrasound did not significantly enhance the prediction of femoral strength compared to femoral BMD measurements alone. Given the substantial differences between the in vitro and in vivo situations, this finding does not necessarily contradict emerging clinical data indicating that ultrasound and BMD have comparable and independent predictive ability for hip fracture risk. Reasons for the apparent discrepancy are discussed, including the enhanced accuracy of DXA in vitro. Nevertheless, it is suggested that further fundamental investigations into the efficacy of current ultrasonic techniques are warranted.

Biomechanical Phenomena↗
PubMedDate not supplied

Kinetics of ultrasonic disinfection of Escherichia coli in the presence of titanium dioxide particles.

The ultrasonic disinfection of Escherichia coli was carried out in the presence of anatase-type TiO2 particles, and the effectiveness of the combination of ultrasonic irradiation with TiO2 addition was verified. The rate constant was determined from the plot of the common logarithm of the survival cell ratio versus the ultrasonic irradiation time using first-order kinetics. In the absence of particles, the rate constant was proportional to the ultrasonic power. When ultrasonic disinfection was carried out in the presence of TiO2 particles, which have a radical generation ability, the rate of disinfection was remarkably faster than that in the absence of TiO2. In the presence of silica particles, which have no radical generation ability, the rate of disinfection was the same as that in the absence of TiO2. These results suggest that the radical generation ability of TiO2 appeared as a result of the ultrasonic irradiation. The effect of the amount of TiO2 on the rate of disinfection was also examined. The rate constant for disinfection in the presence of TiO2 was saturated to a certain value and was represented using the Langmuir-type equation. The proposed model well describes the effects of the ultrasonic power and the amount of TiO2 on the rate constant for disinfection.

Cell Survival↗
PubMed2003

Lung deposition in cystic fibrosis patients using an ultrasonic or a jet nebulizer.

This study was conducted to compare pulmonary deposition following inhalation with an ultrasonic and a jet nebulizer in CF patients under conditions relevant to practice. The marker substance used to estimate the relative lung bioavailability was sodium cromoglycate (SCG), which is poorly absorbed from the gastrointestinal tract, but is completely absorbed from the lungs. Ten CF patients (aged 9-21 years) used an ultrasonic nebulizer (Multisonic compact 2.4 MHz) and a jet nebulizer (Parimaster, LC Plus Turbo) in a crossover design to inhale a solution containing 20 mg of SCG and a beta(2)-agonist. Urine was collected in five fractions until 12 h p. a., and the excreted SCG was determined by means of HPLC. Prior to each inhalation, the patients' pulmonary function was measured employing a Pneumoscope. Using the ultrasonic nebulizer, the amount of SCG excreted in urine was significantly greater than that after inhalation with the jet nebulizer (1.43 +/- 0.47 mg vs. 1.04 +/- 0.47 mg; p = 0.002), despite the larger residual volume in the ultrasonic nebulizer. The absorption half-life for SCG following ultrasonic nebulization was significantly shorter when compared with jet nebulization (84 +/- 14 min vs. 101 +/- 19 min; p = 0.005), being suggestive of a more peripheral deposition. Furthermore, an inverse relationship was found between absorption half-life and FEV(1) (% pred.) (r = -0.655, p = 0.04) or MMEF(75/25) (% pred.) (r = -0.844, p = 0.031), but only with the ultrasonic nebulizer. In conclusion, the ultrasonic nebulizer tested when used for inhalation in CF patients was found to be at least equivalent to the jet nebulizer.

Adolescent↗
PubMed1994

Ultrasonic texture and volume of testicles in infertile men.

Ultrasound scanning of the testes and surgical biopsy were performed in 95 infertile men to evaluate the use of ultrasound in male infertility. Ultrasonic testicular volume was calculated using three measurements and the formula of an ellipsoid, and the ultrasonic texture was evaluated and given a score from 1 to 5, indicating increasing degrees of irregularity. The median score was 3 (range 1-5), which was higher than previously found in normal men (median score 2; range 1-5; P < 0.0001). The ultrasonic texture score was lower in testes with a uniform pattern of 100% spermatogenic tubules compared with the rest, both for the right (P < 0.001) and for the left (P < 0.0005) testis. Texture score was correlated with the number of obliterated tubules for both testes (P < 0.001). The mean ultrasonic testicular volume of the right testis was 10.30 ml, and that of the left 10.26 ml. Both were smaller compared with the findings in normal men (P < 0.0001). Ultrasonic testicular volume was negatively correlated with texture score (P < 0.001). A positive correlation between ultrasonic volume and sperm count was seen (P < 0.001). Sperm count was negatively correlated with texture score if calculated together with data from 119 men from the general population (P < 0.001). The study shows that ultrasonic volume and texture are valuable parameters in the evaluation of infertile men.

Adult↗
PubMed2001

Model-based estimation of ultrasonic echoes. Part II: Nondestructive evaluation applications.

Accurate estimation of the ultrasonic echo pattern leading to the physical property of the object is desirable for ultrasonic NDE (nondestructive evaluation) applications. In Part I of this study, we have presented a generalized parametric ultrasonic echo model, composed of a number of Gaussian echoes corrupted by noise, and algorithms for accurately estimating the parameters. In Part II of this study, we explore the merits of this model-based estimation method in ultrasonic applications. This method produces high resolution and accurate estimates for ultrasonic echo parameters, i.e., time of flight (TOF) amplitude, center frequency, bandwidth, and phase. Furthermore, it offers a solution to the deconvolution problem for restoration of the target response, i.e., ultrasonic reflection and transmission properties of materials, from the backscattered echoes. The model-based estimation method makes deconvolution possible in the presence of significant noise. It can also restore closely spaced overlapping echoes beyond the resolution of the measuring system. These properties of the estimation method are investigated in various ultrasonic applications such as transducer pulse-echo wavelet estimation, subsample time delay estimation, and thickness sizing of thin layers.

Journal Article↗
PubMed2005

Tomographic imaging of an ultrasonic field in a plane by use of a linear array: theory and experiment.

Quantitative ultrasonic characterization of in-homogeneous and anisotropic materials is often difficult due to undesired phenomena such as beam steering and phase aberration of the insonifying field. We introduce a method based on tomographic reconstruction techniques for the visualization of an ultrasonic field using a linear array rotated in a plane. Tomographic reconstruction of the ultrasonic field is made possible through the phase-sensitive nature of the tall, narrow piezoelectric elements of a linear array that act as parallel line integrators of the pressure field. We validate the proposed imaging method through numerical simulations of propagated ultrasonic fields based upon the angular spectrum decomposition technique. We then demonstrate the technique with experimental measurements of two textile composites and a reference water path. We reconstruct images of the real and imaginary parts of a transmitted 2 MHz ultrasonic field that are then combined to reconstruct images of the power and unwrapped phase. We also construct images of the attenuation and phase shift for several regions of the composites. Our results demonstrate that tomographic imaging of an ultrasonic field in a plane using a rotated linear array can potentially improve ultrasonic characterization of complex materials.

Computer Simulation↗
PubMed1967

Use of ultrasonic energy in assessing microbial contamination on surfaces.

Ultrasonic tanks were evaluated for their ability to remove viable microorganisms from various surfaces for subsequent enumeration. Test surfaces were polished stainless steel, smooth glass, frosted glass, and electronic components. The position of contaminated surfaces in relation to the ultrasonic energy source, distance of the ultrasonic source from the test surfaces, and temperature of the rinse fluid were some of the factors which influenced recovery. Experimental systems included both naturally occurring microbial contamination and artificial contamination with spores of Bacillus subtilis var. niger. The results showed that ultrasonic energy was more reliable and efficient than mechanical agitation for recovering surface contaminants. Conditions which increased the number and percentage of microorganisms recovered by ultrasonic energy were: using a cold rinse fluid, placing the sample bottle on the bottom of the ultrasonic tank, and facing the contaminated surfaces toward the energy source. It was also demonstrated that ultrasonic energy could be effectively used for eluting microorganisms from cotton swabs.

Journal Article↗
PubMed1998

Randomised crossover trial of salbutamol aerosol delivered by metered dose inhaler, jet nebuliser, and ultrasonic nebuliser in chronic lung disease.

AIMS: To compare the efficacy of salbutamol delivered by metered dose inhaler (MDI), jet nebuliser, and ultrasonic nebuliser in ventilated infants with chronic lung disease. METHODS: Twenty preterm ventilated infants with chronic lung disease were enrolled in two studies. In study 1 (n = 10), each infant was given 200 micrograms of salbutamol at 4 hour intervals and in random sequence from a metered dose inhaler-spacer device, a jet nebuliser, and an ultrasonic nebuliser with a small medication cup. The infants were monitored for heart rate, transcutaneous pO2, pCO2, and oxygen saturation, respiratory system resistance and compliance before and after each treatment. Infants in study 2 (n = 10) were similarly studied except for the use of a different jet nebuliser. RESULTS: The mean (SEM) maximum percentage decreases in respiratory system resistance, observed at 30 minutes after aerosol delivery were study 1: MDI: 44.3 (4.3)%; jet: 32.3 (3.4)%; ultrasonic: 56.1 (3.2)%; study 2: MDI: 28.6 (1.0)%; jet: 16.9 (1.4)%; ultrasonic: 42.1 (1.6)%. During the first hour after treatment, a significantly faster heart rate and higher transcutaneous pO2 were associated with the use of the ultrasonic nebuliser or MDI than with the jet nebulisers in both studies. The use of the ultrasonic nebuliser but not the other devices also resulted in a lower transcutaneous pCO2 and improved respiratory system compliance in study 2. CONCLUSIONS: These findings suggest that among the devices tested, the delivery of salbutamol aerosol to the lower respiratory tract was greatest using the ultrasonic nebuliser, and least with the jet nebulisers.

Administration, Intranasal↗
PubMed1995

Sensitive detection of abnormal aortic architecture in Marfan syndrome with high-frequency ultrasonic tissue characterization.

BACKGROUND: Aneurysmal dilation of the aorta with subsequent rupture or dissection occurs frequently in patients with Marfan syndrome and is the primary cause of morbidity. These complications are related to the altered composition and disorganized structure of the aortic media. Our goal was to use high-frequency ultrasonic tissue characterization to identify these structural changes in abnormal aorta from patients with Marfan syndrome. We measured integrated backscatter and anisotropy of backscatter of ultrasound from specimens of aorta from patients with Marfan syndrome undergoing aortic root replacement and compared these values with those from aortic specimens of patients without clinical aortic pathology. METHODS AND RESULTS: Aortic tissue was obtained at the time of surgery from 11 patients with Marfan syndrome undergoing repair of an aortic aneurysm or dissection. Normal tissue was obtained at the time of autopsy from 8 patients without evidence of aortic disease. Acoustic microscopy at 50 MHz was performed to measure integrated backscatter from each specimen. The magnitude of ultrasonic anisotropy of backscatter for each tissue type was determined as an index of the three-dimensional (3D) organization of the vessel matrix. The collagen content of each specimen was determined with a hydroxyproline assay. Marfan aortas exhibited less backscatter than did normal aortas (-40.9 +/- 2.9 versus -32.6 +/- 2.2 dB for patients with Marfan syndrome and healthy subjects, respectively, P < .0001). No significant difference in collagen concentrations was observed between normal and Marfan aorta (262.7 +/- 52.7 versus 282.4 +/- 41.8 mg/g tissue for normal and Marfan aortas, respectively, P = .42), despite the large difference in backscatter. Histological analysis revealed striking differences in both the amount and organization of the elastin in the aortic aneurysm segments from patients with Marfan syndrome compared with normal aorta. Normal aorta was characterized by well-formed elastin fibers arranged in a lamellar pattern. The media from aneurysms in Marfan aorta exhibited a profound decrease in elastin content that was associated with loss of the highly aligned and ordered lamellar arrangement. The directional dependence of scattering, or ultrasonic anisotropy, also differed dramatically between the two tissue types. Backscatter from normal aorta decreased substantially when the media was insonified parallel compared with perpendicular to the principal axis of the elastin fibers. Marfan aorta exhibited a much smaller directional dependence of scattering. Normal aortas manifested a 14-fold greater ultrasonic anisotropy than did Marfan aortas (24.1 +/- 3.7 versus 12.4 +/- 3.3 dB for normal and Marfan aortas, P < .0001), which is indicative of the profound extent of matrix disorganization in Marfan syndrome. CONCLUSIONS: These data show that high-frequency ultrasonic tissue characterization sensitively detects changes in vessel wall composition and organization that occur in the aorta of patients with Marfan syndrome. Aortic segments from these patients manifested a significant decrease in integrated backscatter compared with normal aorta (approximately 8 dB, or greater than a 6-fold decrease in scattering). A 15-fold reduction in the ultrasonic anisotropy of Marfan tissue was observed, which suggests a marked disorganization of the 3D architecture of these aortas. These data support the hypothesis that high-frequency ultrasonic tissue characterization may be useful for identifying abnormalities of vessel wall composition, architecture, and material properties.

Adult↗
PubMed1984

Abdominal ultrasonic scanning versus lymphangiography in testicular cancer.

Abdominal ultrasonic scanning was compared to lymphangiography and intravenous urography in 50 patients with testicular cancer. In 25 lymphangiographic stage I patients, the ultrasonic scanning was normal in all cases, too. In 5 out of 25 lymphangiographic stage II patients, the ultrasonic examination demonstrated a wider extension of the retroperitoneal metastases than combined lymphangiography and urography. The ultrasonically demonstrated masses were proven to contain malignant cells through an ultrasonically-guided fine-needle puncture in all 5 cases. Sufficient planning of the radiation ports would not have been possible in these patients without the additional ultrasonic scanning. In monitoring of the therapeutic response, ultrasonic scanning was found superior to lymphangiography.

Humans↗
PubMedDate not supplied

Ultrasonic indentation: a procedure for the noninvasive quantification of force-displacement properties of the lumbar spine.

BACKGROUND: Alterations in the normal force-displacement (FD) properties of spinal tissues have been associated with specific forms of pathology, such as degenerative disk disease. Unfortunately, few current procedures exist that assess spinal FD properties in an accurate, reliable, and noninvasive manner. Consequently, the clinical relevance of the relation between spinal disorders and spinal FD properties is not fully understood. OBJECTIVE: To investigate the accuracy and reliability of spinal FD measures obtained through use of a procedure in which real-time ultrasonic imaging (ultrasonic indentation) is used during load-controlled external indentation. SETTING: McCaig Centre for Joint Injuries and Arthritis Research, University of Calgary. METHODS: The bench-top accuracy and reliability of ultrasonic indentation were assessed by cyclic indentation of a spring-mounted platform. These data were compared with criterion data derived from a materials testing machine. A porcine preparation was then used to assess the accuracy of ultrasonic indentation-generated estimates of vertebral displacement in comparison with a criterion of optically tracked displacement. In addition, previously unreported parameters relating to indentation accuracy (frame deflection and off-axis loading) were characterized. RESULTS: Reliability of ultrasonic indentation ranged between 0.99 and 1.00 (intraclass correlation coefficient). Error values in force, displacement, and stiffness ranged from 0.81% to 13.62% over varying experimental conditions. CONCLUSIONS: Ultrasonic indentation is a unique procedure that is capable of assessing, noninvasively, FD properties of spinal tissues, including vertebral displacement in the indentation plane. The results of this study suggest that ultrasonic indentation is a potentially useful technique for quantifying spinal FD properties in vivo.

Animals↗
PubMed2001

[Precision and reliability of Orbscan and ultrasonic pachymetry].

PURPOSE: To compare the accuracy and reproducibility of the orbscan pachymetry and ultrasonic pachymetry in the normal eye and in the penetrating keratoplasty eye. METHODS: Pachymetric measurements were assessed in 50 eyes of 25 normal patients and 50 eyes of 48 patients who had undergone penetrating keratoplasty using both Orbscan II and ultrasonic pachymetry (Tomey SP-2000). For each eye, 2 successive measures were recorded with both instruments. For both devices, the default setting was used. Orbscan pachymetry maps were divided into 5 groups using a modification of Liu's classification. RESULTS: Orbscan pachymetry strongly correlated with ultrasonic pachymetry (rs = 0.91; p < 0.001). Ultrasonic pachymetry values and Orbscan pachymetry values showed no significant differences in the normal group (respectively, 557 microns +/- 36 and 555 microns +/- 34; p > 0.05). Ultrasonic pachymetry values and orbscan pachymetry values were significantly different in the penetrating keratoplasty group (respectively, 571 microns +/- 52 and 550 microns +/- 54; p < 0.001). The best value for the acoustic factor for Orbscan pachymetry in the penetrating keratoplasty group was 0.89. Ultrasonic pachymetry reproducibility and Orbscan pachymetry reproducibility were not significantly different (0.86% +/- 0.61 v. 0.67% +/- 0.63; p = 0.13 in the normal group; 1.22% +/- 0.81 v. 1.23% +/- 1.13; p = 0.92, in the penetrating keratoplasty group). Both pachymetry methods showed less reproducibility in the penetrating keratoplasty group than in the normal group (p < 0.02). Thinnest point localization was significantly different in both groups (p < 0.001). In 66% of the normal group, the thinnest point of the cornea was located in inferotemporal quadrant. This point was located at an average of 0.63 +/- 0.25 mm from the visual axis in the normal group and 1.60 +/- 0.81 mm in the penetrating keratoplasty group (p < 0.001). Whereas "Centered round" (40%) and "centered oval" (34%) were the most common patterns in the normal group, "decentered oval" (40%) and "irregular" (30%) were more frequent in the penetrating keratoplasty group (p < 0.001). CONCLUSION: Orbscan pachymetry strongly correlated with ultrasonic pachymetry. Reproducibility of both methods is excellent and not significantly different. Thinnest point localization and pachymetric map classification are significantly different in normal eyes and in penetrating keratoplasty eyes.

Child↗
PubMed1979

Localization of hormone-producing gastrointestinal tumours by ultrasonic scanning.

The value of ultrasonic scanning in the localization of hormone producing gastrointestinal tumours was assessed in 16 patients. Fifteen patients had Zollinger-Ellison syndrome and one patient had a VIP tumour. In four patients with Zollinger-Ellison syndrome ultrasonic scanning demonstrated a solid mass lesion of the head of the pancreas of 2.2.4 and 8 cm respectively. One of these diagnoses was verified by autopsy, one was also found by subsequent CT-scanning and angiography. In one patient ultrasonic scanning demonstrated a 3 cm tumour of the tail of the pancreas. At ultrasonically guided percutaneous fine needle biopsy tumour cells were aspirated. Biochemistry confirmed a VIP tumour. In 11 patients ultrasonic scanning was normal. By laparotomy in nine of these tumours of 1--3 cm were found in three patients 5.9 and 15 months after scanning and in two patients multiple 0.5 cm tumours within the duodenal wall were demonstrated one half and 9 months after ultrasound. In four patients tumours were not demonstrated by surgery. Two of the 11 patients were not operated upon, and the tumours have not been localized. The advantages of the complete atraumatic, rapid and relatively cheap ultrasound technique and the ability of an ultrasonically guided biopsy for the demonstration of malignancy justify ultrasonic scanning to be an initial method of investigation in the localization of hormone producing gastrointestinal tumours.

Evaluation Studies as Topic↗
PubMed1997

Clinical importance of measuring coronary graft flows in the revascularized heart. Ultrasonic or electromagnetic?

BACKGROUND: In the past, routine coronary graft flow measurement at the end of coronary artery bypass grafting (CABG) was not universally adopted by cardiac surgeons due to the lack of reliable flow measurement techniques. The purpose of this study was to investigate the efficacy of ultrasonic and electromagnetic techniques in coronary graft flow measurements and to determine the relationship, if any, between intraoperative ultrasonic or electromagnetic coronary graft flows and postoperative early clinical outcome. METHODS: We studied 66 consecutive patients who underwent elective CABG using internal thoracic artery (ITA) and reversed saphenous vein graft (SVG) conduits. All patients were males with the mean age of 65 +/- 1 yrs (range = 45 to 80 yrs). Coronary bypass graft flows (both ITA and SVG) were determined by the use of both ultrasonic and electromagnetic flowmeters. In addition, the flow waveform pattern was continuously recorded and analyzed with the ultrasonic technique. In this prospective non-randomized study, the following variables were considered in the forward stepwise multivariate regression analysis of the data: age, weight, body surface area, ejection fraction, perfusion and ischemia times, number of grafts, amount of allogenic banked blood, platelets, fresh frozen plasma transfusions, cardiac output/index, ultrasonic (USF) and electromagnetic flows (EMF), length of intensive care unit (ICU) and hospital stays, and early (30-day) mortality. RESULTS: Based on their location, 226 grafts were divided into four groups: (I) ITA to left anterior descending (LAD) (n = 66) 34 +/- 2.5 ml/min USF and 45 +/- 4.4 ml/min EMF; (II) SVG to circumflex (CX) (n = 62) 33 +/- 2.4 m/min USF and 58 +/- 4.9 ml/min EMF; (III) SVG to diagonal (DIAG) (n = 37); 30 +/- 3.5 ml/min USF and 50 +/- 6.0 ml/min EMF; (IV) SVG to right coronary artery (RCA) (n = 61); 36 +/- 3.1 ml/min USF and 56 +/- 5.3 ml/min EMF. Electromagnetic flow measurements were higher than USF values in all locations (p < 0.05). Difficulties in obtaining proper contact with the vessel wall and finding suitable size probes were major drawbacks in measurement of ITA graft flow by the use of electromagnetic technique. All flow measurements were done within 10 minutes or less. There was no demonstrable correlation between the length of stay (ICU and hospital), and coronary graft flows at the ITA to LAD, SVG to DIAG, or SVG to CX locations. However, ultrasonic coronary graft flows at the SVG to RCA location had a significant inverse correlation with the length of ICU and hospital stays (r = -0.45, p < 0.0005 for both). Early mortality was unaffected by the intraoperative coronary graft flow values (p = NS). CONCLUSIONS: The ultrasonic flowmeter is well-suited for intraoperative assessment of arterial and venous coronary graft flows at the completion of CABG. There is a real potential for using intraoperative graft flow values to predict early outcome after coronary bypass.

Aged↗
PubMed1987

Techniques of liver resection. Comparison of suction knife, ultrasonic dissector, and contact neodymium-YAG laser.

Liver resections were performed in 18 pigs with an inexpensive disposable plastic suction knife, an ultrasonic dissector, or a contact neodymium (Nd)-YAG laser. Technical aspects and intraoperative and postoperative data were compared. Intraoperative blood loss was less with the suction knife (112 +/- 28 mL) than with the ultrasonic dissector (149 +/- 45 mL) or Nd-YAG laser (174 +/- 25 mL). Operating time was similar in all groups. The number of ligatures used in the Nd-YAG laser group (12 +/- 1) was significantly less than in the ultrasonic dissector (27 +/- 2) or suction knife (32 +/- 2) groups. In the ultrasonic dissector group, there was an increase in postoperative white blood cell count and liver enzyme levels compared with the other two groups. Light microscopy revealed dilated bile ducts in the ultrasonic dissector resection group, which may reflect biliary stasis. There were no significant differences in mortality among the three experimental groups. Results indicated that the ultrasonic dissector and the contact laser method were not substantially better than an inexpensive, easily modified plastic suction catheter in performing a major nonanatomic liver resection in piglets.

Animals↗