Lygia Stewart

Causes and Prevention of Laparoscopic Bile Duct Injuries: Analysis of 252 Cases from a Human Factors and Cognitive Psychology Perspective

ObjectiveTo apply human performance concepts in an attempt to understand the causes of and prevent laparoscopic bile duct injury. Summary Background DataPowerful conceptual advances have been made in understanding the nature and limits of human performance. Applying these findings in high-risk activities, such as commercial aviation, has allowed the work environment to be restructured to substantially reduce human error. MethodsThe authors analyzed 252 laparoscopic bile duct injuries according to the principles of the cognitive science of visual perception, judgment, and human error. The injury distribution was class I, 7%; class II, 22%; class III, 61%; and class IV, 10%. The data included operative radiographs, clinical records, and 22 videotapes of original operations. ResultsThe primary cause of error in 97% of cases was a visual perceptual illusion. Faults in technical skill were present in only 3% of injuries. Knowledge and judgment errors were contributory but not primary. Sixty-four injuries (25%) were recognized at the index operation; the surgeon identified the problem early enough to limit the injury in only 15 (6%). In class III injuries the common duct, erroneously believed to be the cystic duct, was deliberately cut. This stemmed from an illusion of object form due to a specific uncommon configuration of the structures and the heuristic nature (unconscious assumptions) of human visual perception. The videotapes showed the persuasiveness of the illusion, and many operative reports described the operation as routine. Class II injuries resulted from a dissection too close to the common hepatic duct. Fundamentally an illusion, it was contributed to in some instances by working too deep in the triangle of Calot. ConclusionsThese data show that errors leading to laparoscopic bile duct injuries stem principally from misperception, not errors of skill, knowledge, or judgment. The misperception was so compelling that in most cases the surgeon did not recognize a problem. Even when irregularities were identified, corrective feedback did not occur, which is characteristic of human thinking under firmly held assumptions. These findings illustrate the complexity of human error in surgery while simultaneously providing insights. They demonstrate that automatically attributing technical complications to behavioral factors that rely on the assumption of control is likely to be wrong. Finally, this study shows that there are only a few points within laparoscopic cholecystectomy where the complication-causing errors occur, which suggests that focused training to heighten vigilance might be able to decrease the incidence of bile duct injury.

Right hepatic artery injury associated with laparoscopic bile duct injury: incidence, mechanism, and consequences.

Because most bile duct injuries involve the common hepatic duct, the right hepatic artery, which is nearby, can also be injured. Reports on the frequency and significance of right hepatic artery injury (RHAI) associated with bile duct injury are sparse but suggest that RHAI increases mortality and decreases the success of the biliary repair. We studied the incidence, mechanism, and consequences of RHAI accompanying major bile duct injury. A total of 261 laparoscopic bile duct injuries were analyzed. Distribution was as follows: class I, 6%; class II, 22%; class III, 61%; and class IV, 11%. RHAI was present in 84 cases (32%): class I, 6%; class II, 17%; class III, 35% (P < 0.04 vs. class I/II); and class IV, 64% (P < 0.007 vs. class I/II/III). RHAI was more commonly associated with abscess, bleeding, hemobilia, right hepatic lobe ischemia, and subsequent hepatectomy (54% with RHAI vs. 11% without RHAI; P < 0.0001). RHAI had no infiuence on the success of the bile duct injury repair or on the mortality rate. Complications occurred more often with RHAI among cases repaired by the primary surgeon (41% RHAIvs.2%no RHAI; P < 0.0001) but not among repairs by a biliary surgeon (3%RHAIvs.2%no RHAI, P = NS; P < 0.0001 primary vs. biliary surgeon). RHAI increased morbidity, and occurred more often with class III and IV injuries refiecting the mechanisms of these injuries. RHAI did not increase the mortality rate or alter the success of biliary repair. Among biliary injuries repaired by the primary surgeon, RHAI was associated with a higher incidence of postoperative abscess, bleeding, hemobilia, hepatic ischemia, and the need for hepatic resection. A similar increase in the complication rate was not seen in patients treated by a biliary specialist.

Pigment gallstones form as a composite of bacterial microcolonies and pigment solids

Although previous studies have suggested that bacteria may contribute to pigment gallstone formation, the current experiments provide evidence that bacteria have a central role in this process. The studies included scanning electron microscopy (SEM) of gallstones, measurements of bacterial adherence to gallstones in vitro, and determination of glycocalyx elaboration by biliary bacteria. Gallstones from 85 patients were studied under SEM. Twenty-five (78%) of 32 pigment stones had evidence of bacterial microcolonies throughout the interior of the stones. Bacteria were absent from the interior of all 35 cholesterol stones studied. Composite stones (stones with separate pigment and cholesterol portions) showed evidence of bacteria within the pigment portions in 14 (78%) of 18 cases. Biliary bacteria adhered to the surface of pigment gallstones in vitro in 35 (90%) of 39 cases, compared with three (8%) of 39 cholesterol stones. Glycocalyx was elaborated by bacteria isolated from nine (82%) of 11 patients with either pigment or composite gallstones. One (33%) of three bacterial species from patients with cholesterol gallstone disease produced glycocalyx. These studies indicate that most pigment gallstones obtained from patients in Western cultures form as a composite of bacteria, bacterial glycocalyx, and pigment solids. Bacteria were found in the majority of black as well as brown pigment stones. These findings serve as the basis of a new theory of pigment stone formation in which bacteria and glycocalyx are postulated to be responsible for the precipitation and subsequent agglomeration of bilirubin pigment. These results also suggest that sepsis is more common in pigment gallstone disease because the stones can serve as a sanctuary for bacteria.

Laparoscopic Repair of Paraesophageal Hiatal Hernias

BACKGROUND Regardless of symptoms, paraesophageal hiatal hernias should be repaired in order to prevent complications. This study reports the University of California San Francisco experience with laparoscopic repair of paraesophageal hiatal hernias, emphasizing the technical steps essential for good results. PATIENTS AND METHODS From May 1993 to September 1997, 55 patients, 27 women and 28 men, with a mean age of 67 years (range, 35-102 years) underwent laparoscopic repair of paraesophageal hernias at the University of California San Francisco. Symptoms, which had been present an average of 85 months before surgery, consisted mainly of pain (55%), heartburn (52%), dysphagia (45%), and regurgitation (41%). Of the four patients who presented with acute illness, two had gastric obstruction, one had severe dyspnea, and one had gastric bleeding. Endoscopy demonstrated esophagitis in 25 (69%) of 36 patients, and 24-hour pH-monitoring demonstrated acid reflux in 22 (67%) of 33 patients. Manometry detected severely impaired distal esophageal peristalsis in 17 (52%) of 33 patients. The preferred operation consisted of reduction of the hernia, excision of the sack and the gastric fat pad, closure of the enlarged hiatus without mesh, and construction of a fundoplication anchored by sutures within the abdomen. RESULTS Of the 55 patients, the operations of 49 were completed laparoscopically using the following reconstructions: Guarner (270-degree) fundoplication (30 patients); Nissen fundoplication (10 patients); and gastropexy (9 patients). Five (9%) operations were converted to laparotomies. The average operating time was 219 minutes; the average blood loss was less than 25 mL; resumption of an unrestricted diet, 27 hours; and mean hospital stay, 58 hours. Intraoperative technical complications occurred in five (9%) patients. One patient died during surgery from a sudden pulmonary embolus. Two (4%) patients required a second operation for recurrent paraesophageal hernias. CONCLUSIONS Laparoscopic repair of paraesophageal hiatal hernias is safe and effective, but the operation is difficult and good results hinge on details of the operative technique and the surgeons experience. In this series, the crus could always be closed securely without using mesh. We realized early that a fundoplication should be a routine step, because it corrects reflux and is the best method to secure the gastroesophageal junction in the abdomen.

Tumors of the Ampulla of Vater: Histopathologic Classification and Predictors of Survival

BACKGROUND The histology and clinical behavior of ampullary tumors vary substantially. We speculated that this might reflect the presence of two kinds of ampullary adenocarcinoma: pancreaticobiliary and intestinal. STUDY DESIGN We analyzed patient demographics, presentation, survival (mean followup 44 months), and tumor histology for 157 consecutive ampullary tumors resected from 1989 to 2006. Histologic features were reviewed by a pathologist blinded to clinical outcomes. Survival was compared using Kaplan-Meier/Cox proportional hazards analysis. RESULTS There were 33 benign (32 adenomas and 1 paraganglioma) and 124 malignant (118 adenocarcinomas and 6 neuroendocrine) tumors. One hundred fifteen (73%) patients underwent a Whipple procedure, 32 (20%) a local resection, and 10 (7%) a palliative operation. For adenocarcinomas, survival in univariate models was affected by jaundice, histologic grade, lymphovascular, or perineural invasion, T stage, nodal metastasis, and pancreaticobiliary subtype (p < 0.05). Size of tumor did not predict survival, nor did cribriform/papillary features, dirty necrosis, apical mucin, or nuclear atypia. In multivariate models, lymphovascular invasion, perineural invasion, stage, and pancreaticobiliary subtype predicted survival (p < 0.05). Patients with pancreaticobiliary ampullary adenocarcinomas presented with jaundice more often than those with the intestinal kind (p = 0.01) and had worse survival. CONCLUSIONS In addition to other factors, tumor type (intestinal versus pancreaticobiliary) had a major effect on survival in patients with ampullary adenocarcinoma. The current concept of ampullary adenocarcinoma as a unique entity, distinct from duodenal and pancreatic adenocarcinoma, might be wrong. Intestinal ampullary adenocarcinomas behaved like their duodenal counterparts, but pancreaticobiliary ones were more aggressive and behaved like pancreatic adenocarcinomas.

The efficacy of medical team training: improved team performance and decreased operating room delays: a detailed analysis of 4863 cases.

Objectives:Medical team training (MTT) has been touted as a way to improve teamwork and patient safety in the operating room (OR). Methods:OR personal completed a 1-day intensive MTT training. A standardized briefing/debriefing/perioperative routine was developed, including documentation of OR miscues, delays, and a case score (1–5) assigned by the OR team. A multidisciplinary MTT committee reviewed and rectified any systems problems identified. Debriefing items were analyzed comparing baseline data with 12 and 24-month follow-up. A safety attitudes questionnaire was administered at baseline and 1 year. Results:A total of 4863 MTT debriefings were analyzed. One year following MTT, case delays decreased (23% to 10%, P < 0.0001), mean case score increased (4.07–4.87, P < 0.0005), and both changes were sustained at 24 months. One-year and 24-month follow-up data demonstrated decreased frequency of preoperative delays (16%–7%, P = 0.004), hand-off issues (5.4%–0.3%, P < 0.0001), equipment issues/delays (24%–7%, P < 0.0001), cases with low (<3) case scores (23%–3%, P < 0.0005), and adherence to timing guidelines for prophylactic antibiotic administration improved (85%–97%, P < 0.0001). Surveys documented perception of improved teamwork and patient safety. A major systems issue regarding perioperative medication orders was identified and corrected. Conclusions:MTT produced sustained improvement in OR team function, including decreased delays and improved case scores. When combined with a high-level debriefing/problem-solving process, MTT can be a foundation for improving OR performance. This is the largest case analysis of MTT and one of the few to document an impact of MTT on objective measures of operating room function and patient safety.

Yield and Performance Characteristics of Endoscopic Ultrasound-Guided Fine Needle Aspiration for Diagnosing Upper GI Tract Stromal Tumors

Background and AimsEUS-FNA is a means of sampling suspected GI stromal tumors (GIST). However, there are limited published data on factors influencing the sampling yield, and on the performance characteristics of this technique in comparison with resection pathology. We analyzed the yield of EUS-FNA for submucosal lesions of the upper GI tract, and determined the performance characteristics of EUS-FNA for diagnosing GISTs.MethodsWe retrospectively reviewed procedural and pathology data from consecutive patients undergoing EUS-FNA of submucosal lesions from two medical centers over a 4-year period. We analyzed the yield of EUS-FNA, and calculated performance characteristics of EUS-FNA for GIST based on resection pathology.ResultsA total of 65 patients underwent EUS-FNA of 66 submucosal lesions during the study period. EUS-FNA was either diagnostic (68%) or suspicious (12%) in a total of 80%. EUS-FNA yielded the following diagnoses: GIST based on cytology and immunohistochemistry (56%), suspected GIST (12%), leiomyoma (9%), other neoplasm (3%), and non-diagnostic (20%). Larger lesion size, gastric location, and presence of on-site cytopathology were associated with higher yield in univariate analysis. Larger needle size and number of FNA passes were not associated with improved yield. Based on resection pathology from 28 specimens, the EUS-FNA performance characteristics for diagnosing GISTs included a sensitivity of 82%, a specificity of 100%, and an overall accuracy of 86%.ConclusionsEUS-FNA provides a high yield for sampling submucosal lesions and is highly accurate for diagnosing GISTs. EUS-FNA has an important role in the evaluation of suspected GISTs.

Intestinal Calcium Absorption Decreases Dramatically After Gastric Bypass Surgery Despite Optimization of Vitamin D Status

Roux‐en‐Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2D‐mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m2). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6‐month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24‐hour urinary Ca decreased, PTH increased, and 1,25(OH)2D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = −0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long‐term skeletal consequences should be investigated.

Laparoscopic bile duct injuries: timing of surgical repair does not influence success rate. A multivariate analysis of factors influencing surgical outcomes

BACKGROUND Many factors contribute to the success of biliary reconstructions following laparoscopic bile duct injury. We previously reported that control of intra-abdominal infection, complete preoperative cholangiography, surgical technique and surgical experience affected the results. There is no consensus, however, on whether the timing of the operation is important. METHODS We examined factors influencing the success of the first repair of 307 major bile duct injuries following laparoscopic cholecystectomy. Factors were assessed for cases initially repaired either by the primary surgeon or a biliary specialist. Bivariate and multivariate analyses were used to determine the significance of comparisons. RESULTS A total of 137 injuries were initially repaired by a biliary surgeon and 163 injuries were initially repaired by the primary surgeon; seven were managed non-surgically. Repairs by primary surgeons were performed earlier than those by biliary surgeons (11 vs. 59 days; P < 0.0001). Bivariate analysis of the entire cohort suggested that later repairs might have been more successful than earlier ones (17 vs. 50 days; P = 0.003). Multivariate analysis, however, showed that the timing of the repair was unimportant (P = 0.572). Instead, success correlated with: eradication of intra-abdominal infection (P = 0.0001); complete preoperative cholangiography (P = 0.002); use of correct surgical technique (P = 0.0001), and repair by a biliary surgeon (P = 0.0001). Separate multivariate analyses of outcomes for primary and biliary surgeons revealed that timing was unrelated to success in either case. CONCLUSIONS The success of biliary reconstruction for iatrogenic bile duct injuries depended on complete eradication of abdominal infection, complete cholangiography, use of correct surgical technique, and repair by an experienced biliary surgeon. If these objectives were achieved, the repair could be performed at any point with the expectation of an excellent outcome. We see no reason to delay the repair for some arbitrary period.

Pathogenesis of pigment gallstones in Western societies: the central role of bacteria.

Bacteria are traditionally accorded a greater role in pigment gallstone formation in Eastern populations. Stone color is thought to predict the presence of bacteria; that is, black stones (Western predominant) are supposedly sterile and brown stones (Eastern predominant) contain bacteria. We previously reported that, regardless of appearance, most pigment gallstones contain bacteria. This study examined, in a large Western population (370 patients), the incidence, appearance, and chemical composition of pigment stones, and the characteristics of gallstone bacteria. One hundred eighty-six pigment stones were obtained aseptically. Bacteria were detected by means of scanning electron microscopy and gallstone culture. Chemical composition was determined by infrared spectroscopy. Bacteria were tested for slime and β-glucuronidase production. Seventy-three percent of pigment stones contained bacteria. Choledocholithiasis was associated with gallstone bacteria. Ca-bilirubinate was present in all pigment stones. Capalmitate was characteristic of infected stones, and more than 75% Ca-carbonate was characteristic of sterile stones. Neither chemical composition nor stone appearance predicted the presence of bacteria. Ninety-five percent and 67% of infected pigment stones contained bacteria that produced slime and β-glucuronidase, respectively. Most pigment stones contained bacteria that produced β-glucuronidase, slime, and phospholipase, factors that facilitate stone formation. Thus bacteria have a major role in Western pigment gallstone formation. Furthermore, gallstone color did not predict composition or bacterial presence.