[Localization of peripheral nerves. Success and safety with electrical nerve stimulation]

Optical signature of nerve tissue-Exploratory ex vivo study comparing optical, histological, and molecular characteristics of different adipose and nerve tissues

Background

During several anesthesiological procedures, needles are inserted through the skin of a patient to target nerves. In most cases, the needle traverses several tissues—skin, subcutaneous adipose tissue, muscles, nerves, and blood vessels—to reach the target nerve. A clear identification of the target nerve can improve the success of the nerve block and reduce the rate of complications. This may be accomplished with diffuse reflectance spectroscopy (DRS) which can provide a quantitative measure of the tissue composition. The goal of the current study was to further explore the morphological, biological, chemical, and optical characteristics of the tissues encountered during needle insertion to improve future DRS classification algorithms.

Methods

To compare characteristics of nerve tissue (sciatic nerve) and adipose tissues, the following techniques were used: histology, DRS, absorption spectrophotometry, high‐resolution magic‐angle spinning nuclear magnetic resonance (HR‐MAS NMR) spectroscopy, and solution 2D ¹³C‐¹H heteronuclear single‐quantum coherence spectroscopy. Tissues from five human freshly frozen cadavers were examined.

Results

Histology clearly highlights a higher density of cellular nuclei, collagen, and cytoplasm in fascicular nerve tissue (IFAS). IFAS showed lower absorption of light around 1200 nm and 1750 nm, higher absorption around 1500 nm and 2000 nm, and a shift in the peak observed around 1000 nm. DRS measurements showed a higher water percentage and collagen concentration in IFAS and a lower fat percentage compared to all other tissues. The scattering parameter (b) was highest in IFAS. The HR‐MAS NMR data showed three extra chemical peak shifts in IFAS tissue.

Conclusion

Collagen, water, and cellular nuclei concentration are clearly different between nerve fascicular tissue and other adipose tissue and explain some of the differences observed in the optical absorption, DRS, and HR‐NMR spectra of these tissues. Some differences observed between fascicular nerve tissue and adipose tissues cannot yet be explained but may be helpful in improving the discriminatory capabilities of DRS in anesthesiology procedures. Lasers Surg. Med. 50:948–960, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

[Anesthesia for medical students : A brief guide to practical anesthesia in adults with a web-based video illustration]

In Germany, Austria and Switzerland, anesthesiologists are the second largest group of physicians in hospitals, but this does not correspond to the amount of anesthesiology teaching that medical students receive in medical schools. Accordingly, the chances of medical students recognizing anesthesiology as a promising personal professional career are smaller than in other disciplines with large teaching components. Subsequent difficulties to recruit anesthesiology residents are likely, although many reasons support anesthesiology as a professional career.Traditional strategies to teach medical students in anesthesiology in medical school consist of airway management or cardiopulmonary resuscitation attempts in manikins. Anesthesiology is a complex interaction consisting of anatomy, physiology, pharmacology, clinical evaluation, experience, knowledge, and manual skills. While some medical schools offer teaching in high fidelity simulators, clinical teaching in the operating room is often limited. When medical students opt for a clinical rotation in anesthesiology, there is a chance to demonstrate the fascinating world of anesthesiology, but this chance has to be utilized carefully by anesthesiologists, as young talents have to be discovered, supported, and challenged.We have put together a short guide for medical students for a clinical rotation in anesthesiology in adults in order to generate basic knowledge and interest in anesthesiology as well as a sense of achievement. Basic knowledge about premedication, induction, maintenance and strategies for anesthesia is discussed. Further, the most important anesthesia drugs are discussed and manual skills, such as intravenous cannulation, mask ventilation, intubation, and regional anesthesia are featured with QR-code based video illustrations on a smartphone or personal computer. We did not discuss possible local mannerism and special patient groups (e. g., children, special medical history), local guidelines, or standard operating procedures.Medical students can be inspired by anesthesiology when not simply told about the tools of the trade and strategies, but instead by gaining knowledge and clinical skills that render a sense of achievement, likely during a clinical rotation into anesthesiology. A short theoretical instruction of anesthesiology enables rapid and targeted orientation even before a clinical rotation. Whether this subsequently results in a higher recruiting chance is currently unknown.