Mehdi Benkhadra

Comparison of fresh and Thiel’s embalmed cadavers according to the suitability for ultrasound-guided regional anesthesia of the cervical region

IntroductionUltrasound-guided punctures are a new technique in anesthesia. However, training in these techniques requires conditions resembling real life as far as possible for learning purposes. Several models are available, but none associates realistic anatomy and lifelike sensations of the passage of fascias. The aim of our study was to compare fresh and Thiel’s embalmed cadavers for ultrasound-guided punctures.MethodsEight fresh cadavers and eight Thiel’s embalmed cadavers were investigated. The cervical region was scanned with an ultrasound probe. Age, sex and body mass index (BMI) were recorded. Visibility of he structures, including sternocleidomastoid (SCM) muscle, anterior and middle scalene muscles, thyroid gland, nerve and the needle, was evaluated as 0 (not visible or bad visibility) or 1 (good visibility). The feeling (“pop”) of passing the fascias was noted as 0 (not felt) or 1 (felt). The possibility of nerve displacement with the needle, the difficulty of intraneural injection and the possibility of nerve penetration and nerve swelling were all recorded as 0 (not possible) or 1 (possible).ResultsThe two groups were comparable in terms of sex, age and BMI. Visibility of the SCM muscle and the needle was better in the Thiel group. Moreover, the “pop” feeling and nerve swelling were significantly more frequently present in the Thiel group. There was no significant difference in terms of the other results between the two groups.ConclusionsCadavers embalmed according to Thiel’s method should be recommended for ultrasound-guided punctures as a realistic and lifelike model.

Ultrasound guidance allows faster peripheral IV cannulation in children under 3 years of age with difficult venous access: a prospective randomized study

Objectives:  Ultrasound‐guided peripheral venous access (USG‐PIVA) presents many advantages over the reference ‘blind’ technique in both adults and children in emergency situations.

A comparison of two emergency cricothyroidotomy kits in human cadavers.

BACKGROUND:We compared two emergency cricothyroidotomy kits designed to avoid lesions during insertion, one based on the Seldinger technique (ST), the other based on the concept of a mechanical detection of the posterior wall of the larynx, with regard to insertion time, success rate, and complication rate. METHODS:Cricothyroidotomy was performed under fiberoptic control in 40 human cadavers embalmed according to Thiel’s technique. The set chosen for use was randomized: new technique (NT) or ST. Duration of the procedure, success rates, and incidence of laryngeal injuries were compared. Traumatic lesions observed with the fiberoptic bronchoscope were anatomically confirmed after dissection. RESULTS:The two groups had comparable epidemiological and anatomical records. Cricothyroidotomy was performed faster with the NT than with the ST (median 54 vs 71 s, P = 0.01). Failure rates were comparable between groups (4 vs 1, P = 0.34), and there were fewer major complications in the posterior tracheal wall with the ST (0 vs 8, P = 0.003). In the ST group, only minor punctiform lesions of the posterior trachea wall were observed in four cases. CONCLUSIONS:In this model, despite a shorter insertion time, the NT produced more lesions and more failures than the ST.

Flexibility of Thiel’s embalmed cadavers: the explanation is probably in the muscles

IntroductionThe flexibility of cadavers conserved using Thiel’s embalming method remains unexplained. We aimed to perform microscopic comparison of muscle and tendon fibres from fresh cadavers (FC), formaldehyde-preserved cadavers (FPC) and cadavers conserved by Thiel’s method (TC).MethodsMuscle and tendon biopsies performed on FC, FPC and TC were conditioned and stained by Masson’s trichrome, Sirius red and Ramon y Cajal, then studied under optical microscope. Alignment and integrity of the muscle and tendon fibres were studied.ResultsWe observed a modification of the muscle fibres in all specimens from TC, regardless of the type of staining used. The muscle fibres taken from FC and FPC were relatively well conserved, both in terms of alignment and integrity. We did not observe any modification of collagen in either muscle or tendon fibres.ConclusionsThe considerable fragmentation of the muscle proteins, probably caused by certain corrosive chemicals, (e.g. boric acid) present in Thiel’s embalming solution, could explain the suppleness of the TC. However, we cannot exclude the possibility of alterations in tendon or muscle collagen, since the experimental methods we used, did not allow for the study of collagen ultrastructure.

Comparison of two techniques for retrograde tracheal intubation in human fresh cadavers.

Background:During retrograde tracheal intubation, the short distance existing between the cricothyroid membrane and vocal cords may be responsible for accidental extubation. The insertion of a catheter into the trachea before the removal of the guide wire may help to cope with this problem. This work was conducted to study the impact of such a modification on the success rate and the duration of the procedure. Methods:Procedures of retrograde tracheal intubation following the classic and modified techniques were randomly performed in cadavers (n = 70). The duration of the procedure from the puncture of the cricothyroid membrane to the inflation of the balloon of the endotracheal tube was measured, and, at the end of the procedure, the position of the endotracheal tube was checked under laryngoscopy. The procedure was considered to have failed if it had taken more than 5 min or when the endotracheal tube was not positioned in the trachea. Results:The mean time to achieve tracheal intubation was similar in both groups (123 ± 51 vs. 127 ± 41 s; not significant), but intubation failed significantly more frequently with the classic technique (22 vs. 8 failures; P < 0.05). All failures were related to incorrect positioning of the endotracheal tube. In four cases, both techniques failed. Conclusions:This efficient, simple modification of the technique significantly increases the success rate of the procedure, without prolonging its duration. These data should be confirmed in clinical conditions but may encourage a larger use of the retrograde technique in cases of difficult intubation.

A new anatomical technique to investigate nerves by imagery

IntroductionWe describe a novel post mortem technique that makes it possible to visualise the nerve structure of the brachial plexus using imaging.Materials and methodsWe dissected in situ the brachial plexus of a cadaver preserved by formaldehyde. A preparation composed of a mixture of baryte powder, water and colorant, was applied to all sides of the brachial plexus and blood vessels of the region under study. A high resolution CT scan was performed. With the aid of Mimics (Materialise) software, segmentation of all the nerve and vascular structures on each of the 650 slices obtained was performed. The Mimics software then compiled all the slices to generate a 3-dimensional STL image.ResultsThe image obtained was printed with a stereolythography printer, to produce a plastic model representing part of the cervico-thoracic spinal cord, the ribs, sternum, scapula, humerus, and clavicle, with the left brachial plexus and the subclavian, axillary and brachial veins and arteries.ConclusionsThis technique has the potential for a wide range of uses: for teaching anatomy, to improve teaching of medical techniques, 3-dimensional modelisation of other nerve structures. The advantage is that the model obtained is a faithful and realistic reproduction.

Accuracy in obtaining 100 μg from 10 mg of morphine for spinal anesthesia

STUDY OBJECTIVE Dilution is often required to obtain appropriate concentrations of intrathecal morphine for analgesia. We compared techniques of diluting by measuring the quantity of morphine actually obtained in the final solution. DESIGN This is an experimental study by 3 experienced anesthesiologists. SETTING The setting is at a university teaching hospital. PATIENTS There are no patients. INTERVENTIONS There are no interventions. MEASUREMENTS Five techniques for obtaining 100 μg from 10 mg/mL were compared: technique 1 (T1) = extraction up to 0.1 graduation on a 1-mL syringe, followed by simple dilution (SD). Technique 2 (T2) = As for T1 but syringe was shaken to mix solution. Technique 3 (T3): SD with 10-mL syringe. Technique 4 (T4): Double dilution with 10-mL syringe. Technique 5 (T5): Extraction up to the 0.1 graduation of a 1-mL syringe, then SD, then shake solution by hand. Three tests using high-performance liquid chromatography with ultraviolet were performed on each syringe prepared 3 consecutive times, namely, at the first (beginning, B), fifth (middle, M) and last (end, E) milliliter or 0.1 mL (depending on syringe type). MAIN RESULTS Average overall concentrations were 208 ±19, 199 ±24, 120 ±13, 136 ±9, and 119 ±16 μg/0.1 mL, T1-T5, respectively. By Kruskal-Wallis test, we classified the techniques according to the magnitude of the difference between the observed concentration of morphine and the desired (theoretical) concentration of 100 μg/0.1 mL. In ascending order, techniques ranked as follows: T5 (smallest difference), T3, T4, T2, and T1 (greatest difference) (P = .0001). CONCLUSIONS There is significant variability in the concentration of morphine actually contained in final solutions after dilution. Morphine presented in different premixed concentrations increases the risk of error. We advocate technique 5 as described above, whereas technique 1 should be prohibited.

Contribution de l'artère auriculaire postérieure à la vascularisation du nerf facial dans l'espace préstylien : étude anatomique et conséquences chirurgicales

INTRODUCTION The aim of our study was to establish a systematization of collateral branches originating from posterior auricular artery to facial nerve in prestylian space. MATERIALS AND METHODS Thirty posterior auricular arteries were studied on 15 fresh cadavers after selective patent blue injection. We observed subsequent colouration of facial nerve. Number and topography of collateral branches were highlighted. RESULTS Posterior auricular artery supplied facial nerve in 67%. Collateral branches dedicated to facial nerve could be classified into three types: type 1 corresponded to one artery in prestylian space, type 2 to several branches in prestylian space; finally type 3 featured several branches originating from posterior auricular artery in prestylian space on the one hand, in superficial retroauricular area on the other hand. CONCLUSION Posterior auricular artery is the main blood supply to facial nerve in prestylian space. In most of the cases, branches to facial nerve originate deeply in parotid space. Nevertheless nervous branches may originate from superficial retroauricular segment of posterior auricular artery. Their damage during surgical procedures as bat ear surgery can cause definitive facial nerve palsy.

Modélisation de l’articulation de l’épaule et navigation

Les auteurs presentent leur experience sur la modelisation de l’articulation gleno-humerale. L’interet d’une telle demarche est de disposer d’un outil qui permette de d’aider au choix d’une prothese articulaire, le choix des meilleures conditions d’implantation, un guide pour l’intervention chirurgicale (navigation) et une aide au suivi de la prothese. Actuellement deux types de prothese existent sur le marche : les prothese dites anatomiques qui consistent en un resurfacage de l’articulation de l’epaule et les protheses dites inversees qui fonctionnent sans coiffe des rotateurs grâce a leur centre de rotation medialise. Dans cette etude nous avons realise des modeles mecaniques reels d’epaules prothesees et non prothesees de maniere a etudier le fonctionnement des implants prothetiques : modele d’epaule inversee et modele d’epaule anatomique. Ces modeles montrent les avantages et les inconvenients de differents morphotypes d’epaule et les criteres geometriques qui semblent les plus pertinents pour prevoir le fonctionnement d’une epaule prothesee. A partir de ces modeles reels nous avons numerise les pieces osseuses de maniere a ce qu’elles puissent etre parametrees en fonction des morphotypes ; il s’agit de formes simples ramenees a des ensembles polygonaux. Nous presentons ici les premiers resultats en particulier concernant les parametres d’encombrement de la prothese et les parametres de deplacement des pieces prothetiques. Les criteres les plus sensibles concernent le centre de rotation de l’epaule et le deplacement des pieces prothetiques par rapport a la presence ou non des muscles de la coiffe et par rapport a l’espace sous - acromial. Deux solutions se presente en cas de difficulte : soit fabriquer des modeles speciaux pour certains morphotypes, soit realiser un osteotomie de la scapula qui adapte ainsi le morphotype de l’epaule a l’implant. Si dans le genou c’est le valgus ou le varus l’element principal de l’equilibre mecanique d’une prothese qu’il faut parfois corriger lorsqu’il s’agit de mettre en place une prothese ; dans l’epaule c’est l’espace sous-acromial et la position de la glene scapulaire qui vont conditionner le fonctionnement mecanique de la prothese que ce soit un modele anatomique ou un modele inverse.

Non-dominant hand quicker to insert peripheral venous catheters under echographic guidance: A randomised trial

BACKGROUND Ultrasound guidance for venous catheter placement requires the use of both hands. An accurate and stable ultrasound image is fundamental for obtaining good quality images, consequently permitting accurate needle placement. We hypothesized that the dominant hand could be used to perform echography, leaving the non-dominant hand available for peripheral venous catheter (PVC) insertion. METHODS Prospective, open-label, randomized, crossover study. Group 1 inserted the PVC with the dominant hand, and held the probe with the non-dominant hand in a first series of 20 insertions, and vice versa in a second series of 20 insertions performed 11days later. Group 2 punctured with the non-dominant hand in Series 1 and vice versa in series 2. The study population comprised female student nurses (aged 20-30years) who had learned neither ultrasound techniques nor catheter insertion. The primary endpoint was time to successful puncture. We recorded age, sex, video game use, and the laterality of hands, feet and eyes. RESULTS One left-handed and nine right-handed nurses were randomized to each group. Puncture by the non-dominant hand was significantly quicker in both series (P<0.001). There was no difference between groups for time to successful puncture with the dominant hand; however a significant difference was found for the non-dominant hand (P<0.01). According to multivariate analysis, the time to successful puncture was significantly lower when the non-dominant hand was used to puncture (adjusted difference 5.6s, P<0.0001). CONCLUSION Using the dominant hand to hold the ultrasound probe and the non-dominant hand to puncture and insert the catheter achieves successful insertion in a significantly shorter time.