Real-time ultrasound guidance for any intervention relies on visualization of needle advancement towards a target. Unfortunately, correct identification of the needle tip is not straightforward, as artifacts always distort the image. The ultrasonic appearance of the needle is often degraded by reverberation, comet tail, side-lobe, beam-width, or bayonet artifacts, which can easily confuse an unprepared operator. Furthermore, the typical needle image, that is, a dot or a straight line (out-of-plane and in-plane approaches, respectively), is also a result of artifacts that hide the real dimensions of the needle. Knowledge and correct interpretation of these artifacts is important for safe practice and is paramount to success when precise needle manipulation is mandatory, for example, when the target is small. In this review, authors discuss the most important needle-related artifacts and provide a physical explanation focusing on implications for everyday practice. Recent advances that allow increased needle visualization and reduction of artifacts are also discussed.

Our data indicate a vasodilatory effect of sevoflurane at surgical level of anaesthesia on large cerebral vessels or a vasoconstriction of the resistance arterioles likely caused by decreased brain metabolism.

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BackgroundPeritoneal insufflation results in hemodynamic changes during laparoscopic cholecystectomy. The aim of the present work is to test whether non-invasive applanation tonometry is suitable for reflecting these hemodynamic alterations.Methods41 patients undergoing laparoscopic cholecystectomies were monitored using the SphygmoCor pulse wave analysing system. Peripheral blood pressures (PBP), central aortic blood pressures (CBP), augmentation index (ALX@HR75) and subendocardial viability ratio (SVR) were measured at rest (Phase 1), after anesthetic induction (Phase 2), after peritoneal inflation (Phase 3) and after peritoneal deflation (Phase 4).ResultsInduction of anesthesia resulted in a statistically significant reduction in both the peripheral blood pressure and central aortic pressures, accompanied by a decrease in augmentation pressure and augmentation index. Peripheral blood pressures did not change along with the peritoneal cavity insufflation, except for a moderate increase in systolic blood pressure. In contrast to this, an increase could be observed in central aortic pressure (106.77 ± 18.78 vs. 118.05 ± 19.85 mmHg, P < 0.01) which was accompanied by increased augementation pressure (18.97 ± 10.80 vs. 31.55 ± 12.01; P < 0.001) and augmentation index (7.31 ± 5.59 vs. 12.61 ± 7.56, P < 0.001), indicating a rise in peripheral arterial stiffness.ConclusionsThe Sphigmocor pulse wave analysis system can be reliably used for detecting and monitoring cardiovascular changes occurring during laparoscopic cholecystectomy.

BackgroundExposure of the OR staff to inhalational anesthetics has been proven by numerous investigators, but its potential adverse effect under the present technical circumstances is a debated issue. The aim of the present work was to test whether using a laminar flow air conditioning system exposure of the team to anesthetic gases is different if the anesthetist works in the sitting as compared to the standing position.MethodsSample collectors were placed at the side of the patient and were fixed at two different heights: at 100 cm (modelling sitting position) and 175 cm (modelling standing position), whereas the third collector was placed at the independent corner of the OR. Collected amount of sevoflurane was determined by an independent chemist using gas chromatography.ResultsAt the height of the sitting position the captured amount of sevoflurane was somewhat higher (median and IQR: 0.55; 0.29–1.73 ppm) than that at the height of standing (0.37; 0.15–0.79 ppm), but this difference did not reach the level of statistical significance. A significantly lower sevoflurane concentration was measured at the indifferent corner of the OR (0.14; 0.058–0.36 ppm, p < 0.001).ConclusionsOpen isolation along with the air flow due to the laminar system does not result in higher anesthetic exposure for the sitting anesthetist positioned to the side of the patient. Evaporated amount of sevoflurane is below the accepted threshold limits in both positions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-016-0284-0) contains supplementary material, which is available to authorized users.