A. Karagianni

Intravenous application of fluorescein for confocal laser scanning microscopy: evaluation of contrast dynamics and image quality with increasing injection-to-imaging time

BACKGROUND Confocal laser scanning microscopy (CLSM) is reported to be a promising tool for in vivo histopathology during an endoscopy. The most commonly used fluorophore is fluorescein sodium given intravenously. However, so far, there are no objective data on contrast dynamics and image quality over time after injection of the substance. OBJECTIVE We aimed to investigate the ideal time period for the best CLSM imaging when using fluorescein sodium. DESIGN The proximal stomachs of 4 anesthetized pigs were examined via standard endoscopes with a portable confocal miniprobe. After injection of 1% fluorescein intravenously (0.1 mL/kg body weight), consecutive sequences were recorded after 1, 2, 3, 5, 8, 20, 30, 40, 50, and 60 minutes. After the procedure, histograms, which represented signal intensity of 20 images (at respective time points), were analyzed from representative regions of interest (ROI). The mean (standard deviation [SD]) pixel value of the pixel values in the ROI were noted. A signal-to-noise ratio (SNR), defined as the ratio between the mean and the SD, was calculated. In addition, 5 images per time period were put into a random order and then blindly evaluated by 2 endoscopists. RESULTS A total of 560 histograms from selected ROIs were analyzed. The SNR decreased significantly after 8 minutes, with the lowest values being reached after 30 minutes. Subjective evaluation of still images also demonstrated a continuous decrease, with the lowest image quality after 30 minutes. A slight increase of image quality after 40 minutes occurred because of extramucosal leakage of fluorescein, with fluorophore deposits in the crypt orifices. CONCLUSIONS In the pig model, fluorescein-based CLSM of the GI tract delivered the best contrast and image quality within the first 8 minutes after injection of the fluorophore. These data might facilitate standardization of the procedure for research purposes but may also help when applying this new technology in a daily routine manner.

Auditory evoked potentials compared with bispectral index for monitoring of midazolam and propofol sedation during colonoscopy.

OBJECTIVES:The purpose of this study was to evaluate and compare Bispectral index (BIS) and A-line auditory evoked potential index (AAI) for monitoring depth of low-dose midazolam and propofol sedation during colonoscopy.METHODS:A total of 115 consecutive patients (ASA I–IV), receiving low-dose midazolam and propofol sedation for colonoscopy, were evaluated. BIS and AAI levels, Observers Assessment of Alertness/Sedation (OAA/S) scores, blood pressure, heart rate, oxygen saturation, as well as the presence or absence of eyelash reflex, patient reaction to an external noxious stimulus and to procedure-related pain were recorded every 1–3 min by a single trained observer.RESULTS:There was a positive correlation between BIS and OAA/S scores (correlation coefficient=0.77) and to a lesser extent AAI and OAA/S scores (correlation coefficient=0.47). BIS and AAI showed significant differences between subsequent levels of sedation (P<0.001). The clustered receiver operating characteristic curve estimate of BIS for the detection of deep sedation was significantly better than that of AAI (P<0.001). Regarding the presence or absence of eyelash reflex and patient reaction to an external noxious stimulus and to procedure-related pain, significant different levels were found for BIS as well as AAI, respectively. Only small changes were observed in hemodynamic variables and oxygen saturation. Overall, our data suggest target BIS levels of slightly above 73 for moderate sedation (defined as OAA/S scores 2 and 3).CONCLUSIONS:BIS and AAI correlated with the level of sedation. Hemodynamic variables were poor indicators of the hypnotic–anesthetic status of the patient. BIS discriminated best between moderate and deep sedation and could complement clinical observation for guidance of moderate sedation.

A novel and practicable ERCP training system with simulated fluoroscopy.

INTRODUCTION Simulators facilitate the acquisition of technical skills for endoscopy. Here, we describe the development, introduction, and first evaluation of a novel generation of mechanical endoscopic retrograde cholangiopancreatography (ERCP) simulation models with simulated fluoroscopy, the X-Vision ERCP Training System. METHODS A custom-made modular ERCP simulation system was built with the use of universally obtainable materials and tools. The trainee controls ERCP activities on two screens: the aspect of the papilla and duodenum is shown on the conventional endoscopy monitor, and the trainees actions in the equivalents of the pancreaticobiliary ducts are shown on the viewing screen of the model. Thereby, the latter screen serves as a substitute for fluoroscopy. Currently, four different models are available, allowing simulation of selective cannulation of the pancreatic or bile duct, intubation of differently arranged papillae, stent placement, and sphincterotomy of a biopapilla. The X-Vision ERCP Training System was first used during an ERCP course attended by 26 endoscopists. Trainees were supervised by an ERCP expert and an experienced ERCP nurse at each training model. The training system was evaluated by the participants and experts using a specific questionnaire. RESULTS During the course there were no technical problems related to the X-Vision ERCP Training System. After sphincterotomy the organic papillae could easily be exchanged within less than 15 seconds. Overall, the X-Vision ERCP Training System achieved favorable results in all categories assessed. CONCLUSION The new X-Vision ERCP Training System is simple and effective. A first evaluation in the context of an ERCP course showed impressive results.

Percutaneously assisted endoscopic surgery using a new PEG-minitrocar for advanced endoscopic submucosal dissection (with videos)

BACKGROUND For endoscopic submucosal dissection (ESD), adequate exposure and visualization of the submucosa for controlled dissection is of eminent importance. OBJECTIVE To determine the feasibility and safety of percutaneously assisted endoscopic surgery (PA-ES) with a new prototype PEG-minitrocar (PMT) for advanced ESD in a porcine model. INTERVENTIONS Placement of the PMT was done in all pigs by the use of a modified pull-through technique. After endoscopic incision of the mucosa, traction was provided for ESD by grasping the incisional margins of the mucosa with a rigid forceps introduced through the PMT, enabling stepwise dissection of the exposed submucosa under direct vision. MAIN OUTCOME MEASUREMENTS Feasibility and safety of the new PMT for PA-ES and en bloc resection of prespecified mucosal areas. RESULTS The study started with acute experiments in 8 animals, followed by a 10-day survival study in another 8 pigs. A total of 20 mucosal pieces were resected. The sizes of the resected pieces varied up to 7.5 x 4.0 cm ex vivo. All but one could be resected en bloc. Percutaneous assistance resulted in an excellent exposure of the submucosal space and enabled stepwise dissection of the submucosal connective tissue. Neither the PMT nor advanced ESD led to relevant complications. CONCLUSIONS We demonstrated the feasibility and safety of a new PMT for advanced ESD. With the use of PA-ES, mucosal pieces of various sizes can be resected en bloc in gastric locations that are difficult to access by flexible endoscopy alone.

Hämodynamik (H), inspiratorische Spitzendrücke (Pinsp) und intraabdomineller Druck (IAD) während Ösophagogastroduodenoskopie (ÖGD) im Schweinemodell

Hintergrund: Die OGD ist ein Standardverfahren zur Diagnostik und Therapie gastrointestinaler Erkrankungen. Es wurde untersucht, ob es uber eine Erhohung des IAD (in Folge der Luftinsufflation) zu hamodynamischen Anderungen kommt, die ursachlich fur (wenn auch seltene) kardiovaskulare Komplikationen sein konnten (ahnlich den Auswirkungen bei Anlage eines Pneumoperitoneums). Methoden: Die Untersuchungen wurden an Schweinen in Allgemeinanasthesie durchgefuhrt. Es wurden vor und wahrend Luftinsufflation zur OGD und nach Absaugen transpulmonale Thermodilutionsmessungen (alle 2 Minuten) zur Erfassung von Herzindex (HI), global enddiastolischen Volumenindex (GEDVI, entspricht Vorlast) und vaskularen Widerstandsindex (SVRI, entspricht Nachlast) durchgefuhrt. Parallel wurden Pinsp, Herzrate (HR), mittlerer arterieller Blutdruck (MAP) und Anderungen des Blasendruckes (zur Bestimmung des IAD) erfasst. Ergebnisse: Es wurden insgesamt 266 Messungen (jeweils zum Zeitpunkt der transpulmonalen Thermodilution) bei 14 Schweinen durchgefuhrt. Wir beobachteten einen hochsignifikanten (P=0,001), reversiblen Anstieg des IAD bei allen Tieren mit vereinzelten Spitzenwerten bis 22mmHg. 3,4% der gemessenen IAD lagen oberhalb 15mmHg (=allgemein akzeptiertes oberes Limit bei der Laparoskopie). IAD und Pinsp korrelierten hochsignifikant (r=0,666, P=0,000). Letztere erreichten Spitzen bis 45 mbar. Wir registrierten nur marginale Anderungen der HR und einen Anstieg des MAP nach initialem Abfall. Der GEDVI zeigte eine signifikante Zunahme. Hinsichtlich des mittleren HI wurden keine wesentlichen Anderungen beobachtet. Beim SVRI allerdings kam es zu einem signifikanten Anstieg, vor allem zum Ende der Luftinsufflation hin. Insgesamt traten weder hamodynamische Instabilitaten, noch ein Abfall der Sauerstoffsattigung auf. Schlussfolgerung: Luftinsufflation wahrend Gastroskopie fuhrt zu teilweise gravierender kardiorespiratorischer Beeintrachtigung. Sie sollte daher auf das notwendige Mas reduziert werden.