A randomized, controlled trial of transcutaneous carbon dioxide monitoring during ERCP.

BACKGROUND: Pulse oximetry, used to monitor oxygen saturation during endoscopy, does not directly measure hypoventilation. Study goals were to determine whether transcutaneous carbon dioxide (PtcCO(2)) monitoring during endoscopic retrograde cholangiopancreatography (ERCP) prevents severe hypoventilation and to assess the accuracy of clinical observation and pulse oximetry in detecting hypoventilation. METHODS: All patients received intensive clinical and electronic monitoring including pulse oximetry. Supplemental oxygen was administered for pulse oximetry < 90%. Patients were randomized to a treatment arm (group 1) where PtcCO(2) monitoring guided sedation or a control arm (group 2) where PtcCO(2) was recorded but unavailable for guiding sedation. RESULTS: Group 1 had significantly fewer episodes of severe carbon dioxide retention (rise in PtcCO(2) >/=40 mm Hg above baseline) than group 2 (0 of 199 versus 5 of 196, respectively, p = 0.03), as well a shorter mean duration of procedure discomfort (8.3% of procedure duration rated as "uncomfortable" versus 11.5%, p = 0.04). Correlations between clinical observation and objective measures of ventilation were poor: level of sedation versus PtcCO(2) (R = 0.3) or pulse oximetry (R = 0.06); slowest respiratory rate versus PtcCO(2) (R = 0.4) or pulse oximetry (R = -0.4). PtcCO(2) rises of greater than 20 mm Hg occurred without oxygen desaturation in 10.7% of patients receiving supplemental oxygen. CONCLUSIONS: Carbon dioxide retention during ERCP is not reliably detected by clinical observation or by pulse oximetry in patients receiving supplemental oxygen. The addition of PtcCO(2) monitoring prevents severe carbon dioxide retention more effectively than intensive clinical monitoring and pulse oximetry alone. The clinical relevancy of this observation needs to be determined in an appropriately designed outcome study.

Comparison of covered versus uncovered wire mesh stents in the canine biliary tract.

Self-expanding wire mesh stents have been developed for endoscopic placement across malignant biliary strictures, but tumor ingrowth may limit the usefulness of open mesh stents. We reasoned that coating the wire mesh might prevent tumor ingrowth. Tissue response to covered and uncovered stents was compared in dogs. Stents were surgically placed in the bile ducts of 22 mongrel dogs through the sphincter of Oddi. Either a silicone-covered stent or an uncovered stent was inserted. Liver function test values remained normal throughout a 1- or 3-month study. Necropsy revealed that all ducts were unobstructed. Bile duct histologic examination revealed mild-to-moderate cellular infiltration in all animals. Mucosal hyperplasia was more marked in the animals with uncovered stents and the bare wires became deeply embedded in bile duct epithelium, whereas the wires of covered stents did not. We conclude that covered stents are well tolerated by the canine bile duct. These results suggest that such stents may be removable, making self-expanding metal stents an appropriate treatment for both benign and malignant biliary strictures.

Cystic duct anatomy: an endoscopic perspective.

Knowledge of the junction of the cystic and common hepatic duct is essential for endoscopic management of biliary tract disease. The cystic and common hepatic ducts were evaluated retrospectively in cholangiograms obtained for a variety of indications in 524 persons. The cysticohepatic junction was adequately visualized in 70%. Medial junctions were noted in 18% and a spiral configuration in 32%, both more common than reported. An 11% occurrence of parallel duct systems was less frequent than expected. In 10% of patients, the cystic duct entered the hepatic duct in the distal third of the extrahepatic biliary tree. The importance of understanding this anatomy is illustrated with selected cases of therapeutic biliary endoscopy and laparoscopic cholecystectomy complications. Suggestions are made for improving performance in this area.

Results of a multicenter trial using a mechanical lithotripter for the treatment of large bile duct stones.

A prospective, uncontrolled trial of the use of a prototype mechanical lithotripter was performed in 116 patients at nine centers. Standard endoscopic approaches had failed to remove all stones, primarily because of large size (80% of patients). For 92% of patients, common bile duct stones were successfully captured and fragmented following the use of this lithotripter. The frequency of pancreatitis and hemorrhage was no greater than with standard endoscopic retrograde sphincterotomy, and complications unique to lithotripter use were not noted. For endoscopists skilled in therapeutic duodenoscopy, this modality should be considered in management of common bile duct stones refractory to standard techniques.

Assigning appropriateness ratings for diagnostic upper gastrointestinal endoscopy using two different approaches.

Methods that combine information in the medical literature with expert clinical judgment are needed to determine the appropriateness of use of a procedure. The purpose of this study is to better understand the reliability and construct validity of this process by comparing ratings of appropriateness for diagnostic upper gastrointestinal endoscopy that were developed using different approaches by two independent groups. Both the RAND/UCLA Health Services Utilization Study (HSUS) and the American Society for Gastrointestinal Endoscopy (ASGE) combined scientific data with expert physician judgment to rate the appropriateness of specific clinical indications for the use of upper gastrointestinal endoscopy. This study applies the ratings developed by each group to a nationally representative sample of 1,585 endoscopies performed on people 65 years of age and older in 1981. HSUS developed indications that could be used to rate all 1,585 procedures; ASGE indications were less comprehensive and applied to 70% (n = 1,115) of procedures. Of those rated by both groups, appropriateness category ratings agreed for 94% of the procedures. However, the procedures not rated by ASGE were unevenly distributed across HSUS appropriateness ratings. Twelve percent of procedures rated as appropriate by HSUS were not rated by ASGE, but 80% of procedures rated as equivocal by HSUS and 73% rated as inappropriate by HSUS were not rated by ASGE, for those procedures rated by both approaches there was good agreement; however, a more explicit and comprehensive method may be required if equivocal and inappropriate use of a procedure is to be identified.

Bipolar electrosurgical sphincterotomy.

We tested a newly developed bipolar sphincterotome. Monopolar and bipolar sphincterotomes were employed to cut small bowel smoothly and hemostatically. The bipolar instrument required 17.1 watts while the monopolar required 29.2 watts; these values are significantly different at p = 0.005. Bipolar sphincterotomies were performed via open surgical access on eight dogs. The animals were allowed to recover and were followed for 6 weeks. There was no evidence of stenosis or common duct dilation at autopsy, and serum alkaline phosphatase and bilirubin were within normal limits. Both sphincterotomes were used to cut tissue in vitro and histological examination displayed no evidence of thermal injury at the return electrode site of the bipolar sphincterotome. The lower power levels required by the bipolar sphincterotome may decrease procedure complications.

The interaction between electrosurgical generators, endoscopic electrodes, and tissue.

Endoscopic monopolar and bipolar devices were compared during cutting and coagulation. It was observed on appropriate animal models that the initial resistance (impedance) values recorded correspond to the normal tissue impedance at the electrode. The subsequent impedance values increase 25 to 50 ohms for the coagulator which relates to tissue desiccation and for the cutting electrodes the impedance increases greater than 1000 ohms during the arcing process. At similar power settings, typical monopolar generators produce maximum power at 300 to 500 ohms while typical bipolar generators produce maximum power at 25 to 100 ohms. With impedances greater than 1000 ohms, monopolar generators are capable of higher power output than are bipolar generators. Since cutting is a high impedance process, bipolar cutting electrodes do not perform as intended with typical bipolar generators. Therefore, bipolar cutting electrodes should be employed with a monopolar generator or a generator designed specifically for their use.

Thermal ablation of the gallbladder.

Gallbladder ablation by means of injection of hot contrast medium was attempted in 13 dogs. Room temperature contrast medium was injected into the gallbladders of two additional dogs (controls). After midline laparotomy was performed to expose the gallbladder, temperature probes were placed in the liver adjacent to the gallbladder, and on the surface and in the lumen of the gallbladder. A 7-F catheter with multiple side holes was placed into the gallbladder. The cystic duct was clamped during the procedure. After injection of boiling contrast medium, the mean temperature in the gallbladder lumen was 80 degrees C; in the adjacent liver, 43.5 degrees C; and on the gallbladder surface, 45.8 degrees C. After the procedure, the cystic duct was unclamped, temperature probes and catheter were removed, and the laparotomy was closed in standard fashion. In the hot contrast medium group, one dog each was sacrificed at 2, 4, 8, and 12 weeks, and at 6 months. Six animals were sacrificed at 1 year. The gallbladder was completely ablated in 11 of 13 animals in the hot contrast medium group. One dog was sacrificed at 8 days because of bile leakage, and another was sacrificed at 17 days because of gallbladder rupture. The two control animals were sacrificed at 12 and 13 weeks, and their gallbladders were normal at that time.

Endoscopic sphincterotomy complications and their management: an attempt at consensus.

Despite its relative safety (in comparison with surgery), and undoubted role in many clinical circumstances, biliary sphincterotomy is the most dangerous procedure routinely performed by endoscopists. Complications occur in about 10% of patients; 2 to 3% have a prolonged hospital stay, with a risk of dying. This document is an attempt to provide guidelines for prevention and management of complications, based on a workshop of selected experts, and a comprehensive review of the literature. We emphasize particularly the importance of specialist training, disinfection, drainage, and collaboration with surgical colleagues.

Labile type-specific antigen of Moraxella catarrhalis.

By using hot acid extract and double-diffusion studies, an antigen isolated from clinical strains of Moraxella catarrhalis, designated the C antigen, was studied. The antigen is labile, relatively trypsin insensitive, and either polysaccharide or glycoconjugate in nature. At least two serologically distinct C antigens have been identified.

In vivo evaluation of monopolar versus bipolar electrosurgical polypectomy snares.

The energy required and tissue damage in bipolar and monopolar polypectomy snares were compared in a canine model. The bipolar snare required an average of 34 joules of energy, whereas the monopolar snare required 228 joules to cut the same diameter of gastric mucosa tended into a polypoid structure (p = 0.0005). The reduced energy delivered to the tissue from the bipolar procedure resulted in only 32% average depth of damage to the underlying gastric wall, whereas the monopolar procedure caused an average 69% (p = 0.001). Surgically created polyps required 247 joules and 69 joules for corresponding monopolar and bipolar polypectomy (p = 0.001). The decreased energy required and the correspondingly reduced damage caused to the underlying bowel wall by the bipolar snare should reduce the incidence of perforation and post-polypectomy syndrome. The bipolar snare completes a local circuit about the snare, eliminating the return electrode and, consequently, the possibility of any return electrode burns. The bipolar snare thus provides an added safety margin during polypectomy.

A new mechanical lithotripter for the treatment of large common bile duct stones.

A prospective uncontrolled multi-center trial of a prototype mechanical lithotripter was performed in 30 patients with common bile duct calculi. Standard endoscopic sphincterotomy had failed to remove all stones, primarily because of large size (26 patients). Stone size ranged from 13 to 35 mm. Forty-three of 45 stones (97%) were successfully captured, fragmented, and extracted with this newly designed mechanical lithotripter. The overall success rate of 93% using this simple and inexpensive modality compares favorably with other methods under investigation for the treatment of common bile duct stones not amenable to routine endoscopic measures.

Choledochal cyst: findings on cholangiopancreatography with emphasis on ectasia of the common channel.

Choledochal cyst is a congenital malformation of the biliary tree that is unusual but by no means rare. During a 13-year period, we encountered eight patients with choledochal cysts who were evaluated with cholangiopancreatography. All of our cases showed an anomalous union of the pancreatic duct and common bile duct, resulting in a long common channel. Review of cholangiopancreatograms also showed ectasia of the common channel in six of the eight patients. Mean length of the common channel, corrected for magnification, was 26 mm (normal, less than 15 mm). The mean corrected diameter of the common channel was 7 mm (normal, 3-5 mm). We conclude that ectasia of the common channel is an important additional radiographic observation in the diagnosis of choledochal cyst. This observation has not been emphasized before.

Effects of biliary obstruction on hepatic clearance of bacteria.

High surgical mortality in patients with obstructive jaundice and sepsis have been attributed to reticuloendothelial system (RES) depression. The purpose of this study was to clarify the effects of mechanical biliary obstruction on RES clearance of pathogenic bacteria by comparing the phagocytic index (K) with the directly measured hepatic uptake of indium 111-labeled bacteria injected into the portal vein of normal dogs and dogs with partial (PBO) or complete biliary obstruction (CBO). No significant difference was observed between the K in normal dogs (0.19 +/- 0.08; n = 6) and that in dogs with PBO (0.24 +/- 0.06; n = 5) or CBO (0.21 +/- 0.03; n = 4). There was no significant difference in uptake of radiolabel by the liver among the three groups of dogs. In our model, biliary obstruction had no effect on hepatic RES function and may not represent a significant determinant of mortality in patients with obstructive jaundice.