Identifying barriers to the use of ultrasound in the perioperative period: a survey of southwestern Ontario anesthesiologists.

BACKGROUND: Ultrasound (US) can be used for many perioperative procedures, but evidence is lacking as to its frequency of use and barrier of application. The objectives of this survey were to determine i) how often US guidance was used perioperatively for vascular access placement, nerve blocks, and heart and lung assessment, and ii) to identify the barriers and the limitations of using US amongst anesthesiologists in southwestern Ontario. METHODS: We conducted a web-based survey in over 40 academic or community hospitals at southwestern Ontario. RESULTS: Of 266 surveys sent, 66 complete surveys were obtained (response rate of 25%). Most respondents (> 80%) reported that US was commonly used for central venous catheter (CVC) insertion, followed by regional blocks; the uses were less frequent for neuraxial blockade and cardiopulmonary assessment. Most respondents wanted to use US more frequently as part of their practice and felt that they already had adequate US training. However, most respondents (59%) reported limited access to US machines in their working institutes as being the major barrier to incorporating US in their daily practice. CONCLUSION: The most common uses of US in anesthesia practice in southwestern Ontario were for CVC insertion and regional blocks. Most anesthesiologists in southwestern Ontario are interested to incorporate US in their daily practice but most were limited by the lack of US resources. Apparently, only providing knowledge and skills teaching may not be sufficient to further improve the US utilization in our region; a matched administrative effort appears to be the next challenge.

The effect of hormone replacement therapy on cognitive function in post-menopausal women.

BACKGROUND: Despite interest in causes of dementia in older persons, particularly in post-menopausal women, it is unclear whether hormone replacement therapy (HRT) is a risk factor. AIM: To assess cognitive function in post-menopausal women with high educational status receiving HRT, compared to non-users. DESIGN: Cognitive functioning was assessed with in women aged 55-60 years with at least university-level education, using the Mindstreams system, a computerized cognitive battery with multiple domains. RESULTS: Of 165 women meeting the inclusion/exclusion criteria, 82 women (49.7%) declined participation. Of the remaining 83, 40 (48.2%) had never received HRT; the remainder was divided into women receiving 5-9 years HRT (n = 29)versus those with >or=10 years HRT (n = 11). There were no statistically significant differences between HRT users and non-users in global scores or sub-domains of cognitive functioning, and no difference between those women receiving HRT for 5-9 years vs. >or=10 years. DISCUSSIONS: Long-term HRT does not appear to impair cognitive functioning in highly-educated women. Recommendations regarding post-menopausal HRT should be made on an individual basis.

Standard vs atraumatic Whitacre needle for diagnostic lumbar puncture: a randomized trial.

In order to define the impact of needle type on post-lumbar puncture headache (PLPH), we performed a prospective, randomized trial comparing the incidence of PLPH in patients undergoing lumbar punctures (LPs) with traumatic vs atraumatic 22-gauge needles. Fifty-eight patients underwent 85 LPs. The incidence of PLPH was 36% in the traumatic vs 3% in the atraumatic group (p = 0.002).

Influence of visible light and ultraviolet irradiation on motility and fertility of mammalian and fish sperm.

OBJECTIVE: The effects of visible light irradiation on sperm motility, fertility, and reactive oxygen species (ROS) formation were investigated and compared in ram and fish (tilapia). BACKGROUND DATA: Low-energy visible light has previously been found to modulate various processes in different biological systems. In the literature, it is accepted that the first step following visible light irradiation is the formation of ROS by endogenous cellular photosensitizers. METHODS: Sperm of ram and tilapia were irradiated with various light sources (400-800 nm white light, 660 nm red light, 360 nm blue light, 294 nm UV), and their motility and fertility rates were measured. The amount of ROS generated by irradiation was estimated using electron paramagnetic resonance (EPR) technique. RESULTS: Sperm taken from tilapia showed higher motility and fertility following red and white light irradiation. In contrast, the motility and fertility of ram sperm were slightly increased only by red light. A negative effect on motility and fertility of sperm of both species was obtained following irradiation with UV and blue light. The amount of ROS produced in irradiated tilapia sperm was much higher than that of ram sperm. CONCLUSIONS: The results show that different wavelengths differentially affect tilapia and ram sperm motility and fertilization. The difference in response to the various light sources might be explained by the different amounts of ROS formation by ram and tilapia, which are in agreement with the physiology of fertilization appropriate to each of these species. Based on these results, it is suggested that in vitro fertilization in mammals should be performed in darkness or at least under red light.

Limited efficiency of a silver selenogallate optical parametric oscillator caused by two-photon absorption.

The nonresonant two-photon absorption (TPA) coefficient in silver selenogallate (AgGaSe(2)) crystals was measured for both ordinary and extraordinary polarizations in the 1300-1600-nm wavelength range. We found a cutoff wavelength for the TPA at between 1400 and 1500 nm, which corresponds to half of the bandgap energy of the AgGaSe(2) crystal. Below the cutoff wavelength we measured the TPA coefficient to be approximately 0.035 cm/MW for the extraordinary polarization and two to three times lower for the ordinary polarization. We compared the AgGaSe(2) samples from two manufacturers and observed a factor of 2 difference in the TPA coefficients. Because of the high TPA, the 1.32-mum pumped AgGaSe(2) optical parametric oscillator conversion efficiency was clipped at a low level.

Photodissociation followed by laser-induced fluorescence at atmospheric pressure and 24 degrees C: a unique scheme for remote detection of explosives.

A unique scheme has been applied for sensitive remote detection of 2,4,6-trinitrotoluene (TNT) vapor trace amounts at atmospheric pressure and 24 degrees C. The detection concept is based on a single laser beam inducing a tandem process: photodissociation of TNT vapor followed by highly selective detection of its photofragments vibrationally excited NO, utilizing laser-induced fluorescence with the A2Sigma+(v' = 0) <-- X2Pi(v'' = 2) transition. A detection sensitivity of at least 8 parts in 10(9) of TNT vapor with a signal-to-noise ratio of approximately 10 has been experimentally verified for an unfocused approximately 5-mJ laser beam, measured at a distance of approximately 15 cm from the TNT sample.

Thermally boosted pumping of neodymium lasers.

Pumping at 885 nm from thermally excited ground-state levels directly to the Nd:YAG upper lasing level is experimentally demonstrated by use of a Ti:sapphire pump laser. This approach utilizes thermal energy contained within the laser medium to provide part of the pump energy required to achieve population inversion. Slope efficiency increased by 12% compared with traditional pump band excitation (lambda(pump) = 808 nm) and by 7% compared with ground-state direct pumping (lambda(pump) = 869 nm). The combined transition from the first and second thermally excited Stark components of the ground state (4I(9/2)) to the upper lasing level (4F(3/2)) has characteristics that make thermally boosted pumping a suitable candidate for use with diode lasers: reasonable absorption (1.8 cm(-1)) and bandwidth (2.7 nm FWHM). A model suggests that, compared with traditional 808-nm pumping, heat could be reduced by 40% by use of thermally boosted pumping.

Does laparoscopic cholecystectomy influence peri-sinusoidal cell activity?

BACKGROUND/AIMS: To investigate the influence of laparoscopic procedures on perisinusoidal cell function. METHODOLOGY: In 31 patients who underwent laparoscopic cholecystectomy for symptomatic cholelithiasis, the serum levels of beta-N-acetyl hexosaminidase (beta-NAH) and hyaluronic acid (HA) were measured. Six female patients, who underwent other laparoscopic procedures, not involving the hepatobiliary system, served as controls. RESULTS: HA serum levels increased significantly in both study and control groups, while beta-NAH serum levels remained within normal values. Post-operative AST and ALT serum levels increased significantly only in the study group. No elevation of serum ALP was noted in any of our patients, and post-operative bilirubin levels did not increase in patients with normal pre-operative levels. CONCLUSIONS: Laparoscopic procedures caused detectable damage to Kupffer and endothelial cells as reflected by elevation of post-operative HA serum levels. The damage to the liver hepatocytes and perisinusoidal cells has no clinical significance and the laparoscopic procedure itself is the probable cause of the Kupffer and endothelial cells damage, while other mechanisms caused damage to the hepatocytes.

Efficient pumping scheme for neodymium-doped materials by direct excitation of the upper lasing level.

An efficient pumping scheme that involves direct excitation of the upper lasing level of the Nd(3+) ion is demonstrated experimentally. The results obtained for direct upper laser level pumping of Nd:YAG R2 (869 nm) and Nd:YVO(4) (880 nm) were compared with traditional approximately 808-nm pump band excitation. A tunable cw Ti:sapphire laser was used as the pump source. In Nd:YAG, the oscillator slope efficiency increased by 10% and the threshold decreased by 11%. In Nd:YVO(4), the slope efficiency increased by 5% and the threshold decreased by 11%. These results agree with theory. The increase in optical efficiency indicates that laser material thermal loading can be substantially reduced.

Highly efficient doubling of a high-repetition-rate diode-pumped laser with bulk periodically poled KTP.

An internal doubling efficiency of 64% at 2 MW/cm(2)was obtained in a single-pass configuration with an uncoated, 1-cm-long, bulk periodically poled KTP crystal placed outside the resonator of a pulsed, diode-pumped Nd:YAG laser. An average of 4.8W of green light was obtained from a 7.5-W pump beam inside the crystal. Doubling efficiency exceeded 50% at levels of 0.75 MW/cm(2). The measured thermal tolerance of the doubling process (FWHM) was 3.3( degrees )C cm, and the measured temperature tuning coefficient was 0.053 nm/( degrees )C .

Highly efficient low-threshold tunable all-solid-state intracavity optical parametric oscillator in the mid infrared.

An intracavity critically phase-matched optical parametric oscillator (OPO) was demonstrated with a LiNbO(3) crystal placed inside the resonator of a diode side-pumped Q-switched Nd:YAG laser. The OPO acted as a singly resonating cavity on the signal with a threshold below 10 MW/cm(2). Output energy as high as 640 microJ was observed at the idler wavelength of 3.7 microm, which corresponds to a conversion efficiency of 1.8% from diode light to idler light. Tunability over the wavelength range 3.3-4.15 microm was obtained by rotation of the LiNbO(3) crystal.

Narrow-linewidth optical parametric oscillator with an intracavity laser gain element.

A demonstration of an optical parametric oscillator and a high-gain laser element operating simultaneously in a common cavity is presented. In such a cavity the signal photons are amplified both in the gain medium and in the nonlinear crystal, whereas the idler photons are generated only in the crystal. The high gain in the laser element reduces the pump threshold for the parametric oscillations. This combined configuration is an efficient, compact design that permits the construction of a tunable source with low pump threshold and narrow linewidth, attained by a wavelength-selective element in the cavity.

Comparison of serum C-reactive protein concentrations for laparoscopic versus open cholecystectomy.

In an attempt to quantify the difference in tissue damage between open cholecystectomy (OC) and laparoscopic cholecystectomy (LC), we have compared in a prospective manner the pre- and post-operative concentrations of serum C-reactive protein (CRP) in 17 patients undergoing LC and 13 patients undergoing OC. In addition, we measured the pre- and postoperative white blood cell counts (WBC), the postoperative body temperature, and the postoperative duration of hospitalization. There were no differences in the preoperative serum CRP concentrations--5.9 +/- 2.62 mg/l (mean +/- SD) for the LC group and 6.12 +/- 2.38 mg/l for the OC group. Serum CRP rose markedly following OC compared to that of patients who underwent LC (128.6 +/- 45.1 mg/l vs 26.8 +/- 10.5 mg/l) (P < 0.001). There were also significant differences in the postoperative WBC count (14,000 +/- 2,900 cells for the OC group vs 10,600 +/- 3,000 cells for the LC group), the postoperative body temperature (37.5 +/- 0.3 degrees C vs 37.0 +/- 0.3 degrees C), and the postoperative hospital stay (5.5 +/- 1.5 days vs 1.9 +/- 0.9 days). There was no correlation between serum CRP concentrations and the other postoperative parameters. These results provide us with biochemical evidence supporting the clinical observation that LC is far less traumatic to the patient than OC.