791. ICU Provider Overestimation of Ventilator-Associated Pneumonia Diagnostic Probability: An Opportunity for Diagnostic Stewardship

Background

Overdiagnosis of ventilator-associated pneumonia (VAP) is common in intensive care units (ICUs). Because VAP is a clinical diagnosis without an easily accessible confirmatory diagnostic test, understanding how ICU physicians practice diagnostic reasoning in suspected VAP is vital to informing diagnostic stewardship efforts. We aimed to assess the accuracy of ICU practitioner estimates of VAP diagnostic probability.

Methods

We conducted a survey of physicians at Michigan Medicine ICUs. Providers were presented with clinical vignettes (Figure 1) in which mechanically ventilated patients developed clinical signs suggestive of VAP and then had radiographic/microbiologic tests performed. Providers were asked to estimate the probability of VAP before and after each presented clinical sign or test result, which were then used to impute provider-estimated likelihood ratios (pLRs) for each clinical sign and diagnostic test. Provider-estimated probabilities and LRs were compared to evidence-based VAP probabilities and LRs (eLRs) derived from systematic reviews and meta-analyses.

Survey Case Example.

Results

Of 102 survey respondents, 54% felt moderately to extremely confident in their ability to accurately diagnose VAP. Providers significantly overestimated the pre and post-test probability of VAP in all clinical scenarios (provider-estimated VAP diagnostic probabilities are visualized using density plots relative to evidence-based diagnostic probability in Figure 2). Median pLRs for nearly all VAP clinical signs and diagnostic tests were also significantly higher than eLRs (Figure 3), most notably for isolated purulent endotracheal secretions (pLR 1.54 vs eLR 0.76, p< 0.01), positive chest radiograph (pLR 6.0 vs eLR 3.55, p< 0.01), and positive bronchoalveolar lavage culture (pLR 5.7 vs eLR 1.37, p< 0.01).

Density Plots of Provider-Estimated vs Evidence-Based Diagnostic Probability of Ventilator-Associated Pneumonia.

Provider-Estimated vs Evidence-Based Diagnostic Likelihood Ratios for Clinical Signs and Test Results Related to Ventilator-Associated Pneumonia.

Conclusion

Physicians routinely overestimated the diagnostic probability of VAP and the positive LRs of possible VAP clinical signs, as well as VAP diagnostic radiographic and microbiologic tests. Educational initiatives addressing and calibrating ICU providers’ perceptions of VAP diagnostic probability warrant investigation as an antimicrobial stewardship tool.

Disclosures

Owen Albin, MD, Charles River Laboratory: Advisor/Consultant|Cipla Pharmaceuticals: Advisor/Consultant|Shionogi Inc: Advisor/Consultant.

Physician perceptions of a multidisciplinary endocarditis team

Infectious endocarditis is a highly morbid infection that requires coordination of care across medical and surgical specialties, often through the use of a multidisciplinary team model. Multiple studies have demonstrated that such conferences can improve clinical outcomes. However, little is known about physicians' impressions of these groups. We surveyed 126 (response rate of 30%) internal medicine, infectious diseases, cardiology, and cardiac surgery providers 1 year after the implementation of an endocarditis team at the University of Michigan. Ninety-eight percent of physicians felt that the endocarditis team improved communication between specialties. Additionally, over 85% of respondents agreed that the group influenced diagnostic evaluation, reduced management errors, increased access to surgery, and decreased in-hospital mortality for endocarditis patients. These results suggest that multidisciplinary endocarditis teams are valued by physicians as a tool to improve patient care and serve an important role in increasing communication between providers.

The effect of gender on operative autonomy in general surgery residents

BACKGROUND

Despite an increasing number of women in the field of surgery, bias regarding cognitive or technical ability may continue to affect the experience of female trainees differently than their male counterparts. This study examines the differences in the degree of operative autonomy given to female compared with male general surgery trainees.

METHODS

A smartphone app was used to collect evaluations of operative autonomy measured using the 4-point Zwisch scale, which describes defined steps in the progression from novice ("show and tell") to autonomous surgeon ("supervision only"). Differences in autonomy between male and female residents were compared using hierarchical logistic regression analysis.

RESULTS

A total of 412 residents and 524 faculty from 14 general surgery training programs evaluated 8,900 cases over a 9-month period. Female residents received less autonomy from faculty than did male residents overall (P < .001). Resident level of training and case complexity were the strongest predictors of autonomy. Even after controlling for potential confounding factors, including level of training, intrinsic procedural difficulty, patient-related case complexity, faculty sex, and training program environment, female residents still received less operative autonomy than their male counterparts. The greatest discrepancy was in the fourth year of training.

CONCLUSION

There is a sex-based difference in the autonomy granted to general surgery trainees. This gender gap may affect female residents' experience in training and possibly their preparation for practice. Strategies need to be developed to help faculty and residents work together to overcome this gender gap.

Invasive Genitourinary Aspergillosis in a Patient with Chronic Lymphocytic Leukemia Treated with Venetoclax: Case Report and Review of the Literature

Novel targeted pharmacotherapies have ushered in a new era in the management of chronic lymphocytic leukemia (CLL). Postmarketing surveillance indicates that some of these agents are associated with unexpected increases in opportunistic infections. In this report, we present a case of primary genitourinary invasive aspergillosis in a patient with CLL treated with venetoclax. We briefly review both genitourinary aspergillosis and infection risks associated with venetoclax treatment for CLL.

The 2018 ISDE achalasia guidelines

Achalasia is a relatively rare primary motor esophageal disorder, characterized by absence of relaxations of the lower esophageal sphincter and of peristalsis along the esophageal body. As a result, patients typically present with dysphagia, regurgitation and occasionally chest pain, pulmonary complication and malnutrition. New diagnostic methodologies and therapeutic techniques have been recently added to the armamentarium for treating achalasia. With the aim to offer clinicians and patients an up-to-date framework for making informed decisions on the management of this disease, the International Society for Diseases of the Esophagus Guidelines proposed and endorsed the Esophageal Achalasia Guidelines (I-GOAL). The guidelines were prepared according the Appraisal of Guidelines for Research and Evaluation (AGREE-REX) tool, accredited for guideline production by NICE UK. A systematic literature search was performed and the quality of evidence and the strength of recommendations were graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Given the relative rarity of this disease and the paucity of high-level evidence in the literature, this process was integrated with a three-step process of anonymous voting on each statement (DELPHI). Only statements with an approval rate >80% were accepted in the guidelines. Fifty-one experts from 11 countries and 3 representatives from patient support associations participated to the preparations of the guidelines. These guidelines deal specifically with the following achalasia issues: Diagnostic workup, Definition of the disease, Severity of presentation, Medical treatment, Botulinum Toxin injection, Pneumatic dilatation, POEM, Other endoscopic treatments, Laparoscopic myotomy, Definition of recurrence, Follow up and risk of cancer, Management of end stage achalasia, Treatment options for failure, Achalasia in children, Achalasia secondary to Chagas' disease.

What factors influence attending surgeon decisions about resident autonomy in the operating room?

BACKGROUND

Educating residents in the operating room requires balancing patient safety, operating room efficiency demands, and resident learning needs. This study explores 4 factors that influence the amount of autonomy supervising surgeons afford to residents.

METHODS

We evaluated 7,297 operations performed by 487 general surgery residents and evaluated by 424 supervising surgeons from 14 training programs. The primary outcome measure was supervising surgeon autonomy granted to the resident during the operative procedure. Predictor variables included resident performance on that case, supervising surgeon history with granting autonomy, resident training level, and case difficulty.

RESULTS

Resident performance was the strongest predictor of autonomy granted. Typical autonomy by supervising surgeon was the second most important predictor. Each additional factor led to a smaller but still significant improvement in ability to predict the supervising surgeon's autonomy decision. The 4 factors together accounted for 54% of decision variance (r = 0.74).

CONCLUSION

Residents' operative performance in each case was the strongest predictor of how much autonomy was allowed in that case. Typical autonomy granted by the supervising surgeon, the second most important predictor, is unrelated to resident proficiency and warrants efforts to ensure that residents perform each procedure with many different supervisors.

Development of quality measures for the care of patients with gastroesophageal reflux disease

BACKGROUND & AIMS

Gastroesophageal reflux disease (GERD) is a common and costly disorder. Symptoms attributed to GERD have a wide spectrum of presentations and complications that have led to complex diagnostic and management algorithms. As such, there is considerable variation in clinical approaches to GERD. In contrast to multiple published guidelines for the management of GERD, there are few validated GERD quality measures. The objective of this study was to use a well-described, formal methodology to develop valid, physician-led quality measures for all aspects of care for patients with GERD.

METHODS

Quality measures were identified from the literature, consensus guidelines, and GERD experts. Eight clinical experts ranked potential measures for validity on the basis of the RAND/University of California, Los Angeles Appropriateness Methodology.

RESULTS

Of the 52 proposed quality measures, 24 were rated as valid, and 1 new measure was developed. These valid measures were related to initial diagnosis and management (9), monitoring (3), further diagnostic testing (4), proton pump inhibitor refractory symptoms (2), symptoms of chest pain (1), erosive esophagitis (3), esophageal stricture or ring (1), and surgical therapy (2). Fifteen of these measures were ranked with the highest validity. Twenty-seven measures were determined to be equivocal; 89% of these were extracted from guidelines that were based on low or moderate level evidence.

CONCLUSIONS

We used RAND/University of California, Los Angeles Appropriateness Methodology to develop quality measures for GERD care. By examining performance on these valid, formally developed quality measures, clinical practices and individual providers can assess their adherence with them and direct quality improvement efforts accordingly.

Single-incision laparoscopic cholecystectomy is associated with improved cosmesis scoring at the cost of significantly higher hernia rates: 1-year results of a prospective randomized, multicenter, single-blinded trial of traditional multiport laparoscopic cholecystectomy vs single-incision laparoscopic cholecystectomy

BACKGROUND

Minimally invasive techniques have become an integral part of general surgery with recent investigation into single-incision laparoscopic cholecystectomy (SILC). This study presents the final 1-year results of a prospective, randomized, multicenter, single-blinded trial of SILC vs multiport cholecystectomy (4PLC).

STUDY DESIGN

Patients with biliary colic and documented gallstones or polyps or with biliary dyskinesia were randomized to SILC vs 4PLC. Data measures included operative details, adverse events, and conversion to 4PLC or laparotomy. Patients were followed for 12 months.

RESULTS

Two hundred patients underwent randomization to SILC (n = 119) or 4PLC (n = 81). Enrollment ranged from 1 to 50 patients with 4 sites enrolling >25 patients. Total adverse events were not significantly different between groups (36% 4PLC vs 45% SILC; p = 0.24), as were severe adverse events (4% 4PLC vs 10% SILC; p = 0.11). Incision-related adverse events were higher after SILC (11.7% vs 4.9%; p = 0.13), but all of these were listed as mild or moderate. Total hernia rates were 1.2% (1 of 81) in 4PLC patients vs 8.4% (10 of 119) in SILC patients (p = 0.03). At 1-year follow-up, cosmesis scores continued to favor SILC (p < 0.0001).

CONCLUSIONS

Results of this trial show SILC to be a safe and feasible procedure when compared with 4PLC, with similar total adverse events but with an identified significant increase in hernia formation. Cosmesis scoring and patient preference at 12 months continue to favor SILC, and more than half of the patients were willing to pay more for a single-site surgery over a standard laparoscopic procedure. Additional longer-term population-based studies are needed to clarify if this increased rate of hernia formation as compared with 4PLC will continue to hold true.

Training and simulation for patient safety

BACKGROUND

Simulation-based medical education enables knowledge, skills and attitudes to be acquired for all healthcare professionals in a safe, educationally orientated and efficient manner. Procedure-based skills, communication, leadership and team working can be learnt, be measured and have the potential to be used as a mode of certification to become an independent practitioner.

RESULTS

Simulation-based training initially began with life-like manikins and now encompasses an entire range of systems, from synthetic models through to high fidelity simulation suites. These models can also be used for training in new technologies, for the application of existing technologies to new environments and in prototype testing. The level of simulation must be appropriate to the learners' needs and can range from focused tuition to mass trauma scenarios. The development of simulation centres is a global phenomenon which should be encouraged, although the facilities should be used within appropriate curricula that are methodologically sound and cost-effective.

DISCUSSION

A review of current techniques reveals that simulation can successfully promote the competencies of medical expert, communicator and collaborator. Further work is required to develop the exact role of simulation as a training mechanism for scholarly skills, professionalism, management and health advocacy.

Effects of large hiatal hernias on esophageal peristalsis

HYPOTHESIS

Anatomic changes induced by large hiatal hernia may alter esophageal pressure topography measurements made during high-resolution manometry.

DESIGN

Retrospective study.

SETTING

Single-institution tertiary hospital.

PATIENTS

Ninety patients with large (>5 cm) hiatal hernias on endoscopy were compared with a control group of 46 patients without hernia selected from the same database of 2000 consecutive clinical high-resolution manometry studies.

INTERVENTION

High-resolution manometry with at least 7 evaluable swallows for analysis.

MAIN OUTCOMES MEASURES

Esophageal pressure topography was analyzed for lower esophageal sphincter pressure, distal contractile integral, contraction amplitude, contractile front velocity, and distal latency time. Esophageal length was measured on esophageal pressure topography from the distal border of the upper esophageal sphincter to the proximal border of the lower esophageal sphincter. Esophageal pressure topography diagnosis was based on the Chicago Classification.

RESULTS

The manometry catheter was coiled in the hernia and did not traverse the diaphragm in 44 patients (49%) with large hernia. Patients with large hernias had lower average lower esophageal sphincter pressures, a lower distal contractile integral, slower contractile front velocity, and shorter distal latency time than patients without hernia. They also exhibited a shorter mean esophageal length. However, the distribution of peristaltic abnormalities was not different in patients with and without large hernia.

CONCLUSIONS

Patients with large hernias had an alteration of esophageal pressure topography measurements and a shortened esophagus. However, the distribution of peristaltic disorders was unaffected by the presence of hernia.

Intermediate results of a prospective randomized controlled trial of traditional four-port laparoscopic cholecystectomy versus single-incision laparoscopic cholecystectomy

BACKGROUND

Minimally invasive techniques have become an integral part of general surgery, with recent investigation into single-incision laparoscopic cholecystectomy (SILC). This study presents a prospective, randomized, multicenter, single-blind trial of SILC compared with four-port cholecystectomy (4PLC) with the goal of assessing safety, feasibility, and factors predicting outcomes.

METHODS

Patients with biliary colic and documented gallstones or polyps or with biliary dyskinesia were randomized to SILC or 4PLC. Data measures included operative details, adverse events, and conversion to 4PLC or laparotomy. Pain, cosmesis, and quality-of-life scores were documented. Patients were followed for 12 months.

RESULTS

Two hundred patients were randomized to SILC (n = 117) or 4PLC (n = 80) (3 patients chose not to participate after randomization). Patients were similar except for body mass index (BMI), which was lower in the SILC patients (28.9 vs. 31.0, p = 0.011). One SILC patient required conversion to 4PLC. Operative time was longer for SILC (57 vs. 45 min, p < 0.0001), but outcomes, including total adverse events, were similar (34% vs. 38%, p = 0.55). Cosmesis scores favored SILC (p < 0.002), but pain scores were lower for 4PLC (1 point difference in 10-point scale, p < 0.028) despite equal analgesia use. Wound complications were greater after SILC (10% vs. 3%, p = 0.047), but hernia recurrence was equivalent for both procedures (1.3% vs. 3.4%, p = 0.65). Univariate analysis showed female gender, SILC, and younger age to be predictors for increased pain scores, while SILC was associated with improved cosmesis scores.

CONCLUSIONS

In this multicenter randomized controlled trial of SILC versus 4PLC, SILC appears to be safe with a similar biliary complication profile. Pain scores and wound complication rates are higher for SILC; however, cosmesis scores favored SILC. For patients preferring a better cosmetic outcome and willing to accept possible increased postoperative pain, SILC offers a safe alternative to the standard 4PLC. Further follow-up is needed to detail the long-term risk of wound morbidities, including hernia recurrence.

Prospective randomized controlled trial of traditional laparoscopic cholecystectomy versus single-incision laparoscopic cholecystectomy: report of preliminary data

BACKGROUND

This study presents preliminary data from a prospective randomized multicenter, single-blinded trial of single-incision laparoscopic cholecystectomy (SILC) versus standard laparoscopic cholecystectomy (4PLC).

METHODS

Patients with symptomatic gallstones, polyps, or biliary dyskinesia (ejection fraction <30%) were randomized to SILC or 4PLC. Data included operative time, estimated blood loss, length of skin and fascial incisions, complications, pain, satisfaction and cosmetic scoring, and conversion.

RESULTS

Operating room time was longer with SILC (n = 50) versus 4PLC (n = 33). No differences were seen in blood loss, complications, or pain scores. Body image scores and cosmetic scores at 1, 2, 4, and 12 weeks were significantly higher for SILC. Satisfaction scores, however, were similar.

CONCLUSIONS

Preliminary results from this prospective trial showed SILC to be safe compared with 4PLC although operative times were longer. Cosmetic scores were higher for SILS compared with 4PLC. Satisfaction scores were similar although both groups reported a significantly higher preference towards SILC.

Multicenter analysis of diaphragm pacing in tetraplegics with cardiac pacemakers: positive implications for ventilator weaning in intensive care units

BACKGROUND

Diaphragm pacing (DP) can replace mechanical ventilation in tetraplegics and in trials has assisted respiration in amyotrophic lateral sclerosis patients. This report describes results of DP in patients with cardiac pacemakers.

METHODS

Prospective, single-center and multicenter, nonrandomized, controlled, interventional protocols under U.S. Food and Drug Administration and/or institutional review board approval were evaluated. Patients underwent laparoscopic diaphragm motor point mapping to identify optimal electrode site for implantation. With diaphragm conditioning, patients were weaned from their ventilator. Perioperative and long-term assessments between the cardiac pacemakers and DP were analyzed for any device-to-device interactions.

RESULTS

Over 300 subjects were implanted from 2000 to 2010. Twenty tetraplegics with cardiac pacemakers and DP were analyzed from 6 sites. Subjects ranged from 19 to 61 years old with DP implantation 6 months to 24 years postinjury. There were no immediate or long-term device to device interactions. All patients achieved diaphragm-paced tidal volumes exceeding their basal requirements and, after conditioning, all patients could go >4 hours without mechanical ventilators; 71% could go 24 hours continuously.

CONCLUSION

DP can be safely implanted in tetraplegics having cardiac pacemakers. Applications for temporary use of DP to maintain diaphragm type 1 muscle fiber and improve posterior lobe ventilation may benefit complex critical care patients.

Biologic prosthesis reduces recurrence after laparoscopic paraesophageal hernia repair: a multicenter, prospective, randomized trial

OBJECTIVE

Laparoscopic paraesophageal hernia repair (LPEHR) is associated with a high recurrence rate. Repair with synthetic mesh lowers recurrence but can cause dysphagia and visceral erosions. This trial was designed to study the value of a biologic prosthesis, small intestinal submucosa (SIS), in LPEHR.

METHODS

Patients undergoing LPEHR (n = 108) at 4 institutions were randomized to primary repair -1 degrees (n = 57) or primary repair buttressed with SIS (n = 51) using a standardized technique. The primary outcome measure was evidence of recurrent hernia (> or =2 cm) on UGI, read by a study radiologist blinded to the randomization status, 6 months after operation.

RESULTS

At 6 months, 99 (93%) patients completed clinical symptomatic follow-up and 95 (90%) patients had an UGI. The groups had similar clinical presentations (symptom profile, quality of life, type and size of hernia, esophageal length, and BMI). Operative times (SIS 202 minutes vs. 1 degrees 183 minutes, P = 0.15) and perioperative complications did not differ. There were no operations for recurrent hernia nor mesh-related complications. At 6 months, 4 patients (9%) developed a recurrent hernia >2 cm in the SIS group and 12 patients (24%) in the 1 degrees group (P = 0.04). Both groups experienced a significant reduction in all measured symptoms (heartburn, regurgitation, dysphagia, chest pain, early satiety, and postprandial pain) and improved QOL (SF-36) after operation. There was no difference between groups in either pre or postoperative symptom severity. Patients with a recurrent hernia had more chest pain (2.7 vs. 1.0, P = 0.03) and early satiety (2.8 vs. 1.3, P = 0.02) and worse physical functioning (63 vs. 72, P = 0.03 per SF-36).

CONCLUSIONS

Adding a biologic prosthesis during LPEHR reduces the likelihood of recurrence at 6 months, without mesh-related complications or side effects.

Endoscopic management of bile duct leaks after attempted laparoscopic cholecystectomy

Fourteen patients with symptomatic bile duct leaks following laparoscopic cholecystectomy were treated using endotherapeutic techniques. Patients presented with abdominal pain, liver test abnormalities, jaundice, leukocytosis, and fever. Twelve leaks originated from cystic duct stumps and two from right posterior hepatic ducts. Distal biliary obstruction, which may have promoted leakage, was present in five patients. Treatment methods included stent insertion with endoscopic sphincterotomy (ES), stent insertion without ES, and nasobiliary tube (NBT) placement without ES. Eleven of 14 patients had prompt resolution of their bile leaks following initial endotherapy. Three patients with continued leakage underwent successful repeat endoscopic retrograde cholangiopancreatography 4-5 days after the initial examination. Cholangiographic evidence of leak closure was documented in all patients, and all remained asymptomatic during an average follow-up period of 18.5 months. Endoscopic therapy is safe and effective treatment for clinically significant bile leaks following laparoscopic cholecystectomy. In our small group of patients, NBT alone did not appear to be as effective as endoprostheses with or without ES. The ideal endoscopic treatment method has not yet been established but will likely vary depending on the site and specific nature of the injury and any concomitant biliary ductal pathology.

Intestinal permeability in the ileal pouch

BACKGROUND

Villous atrophy, mucin changes ('colonic metaplasia'), and chronic inflammation occur to varying degrees in all patients with ileal pouchanal anastomosis whereas acute inflammation (pouchitis) affects a subgroup of patients with prior ulcerative colitis.

AIM

To measure epithelial barrier function looking for possible functional adaptation in ileal 'pouch' mucosa.

PATIENTS

Patients with an ileal pouch prior to ileostomy closure (n = 12), functioning pouch (n = 14), pouchitis (n = 8), and ulcerative colitis (n = 12) were assessed.

METHODS

51Cr-EDTA was administered into the 'pouch' or rectum and urinary recovery over 24 hours was taken as an indication of permeability (barrier function). Histological analysis of 'pouch' biopsy specimens was undertaken.

RESULTS

Mucosal permeability is decreased from median 9.4% (range 5.4% to 39.1%) to 1.4% (range 0.38% to 2.2%) after ileostomy closure (p < 0.002) with levels being negatively correlated with two histological parameters of colonic metaplasia-mucin changes (p = 0.03) and villous atrophy (p = 0.05). Pouchitis was associated with increased permeability 5.9% (1.9% to 19.5%) compared with healthy 'pouch' 1.4% (0.35 to 2.2%) (p < 0.006).

CONCLUSION

Despite the presence of chronic inflammation in the mature 'pouch' functional adaptation with reduced permeability occurs in conjunction with colonic metaplasia.

Potassium loss from skeletal muscle during exercise in man: a radioisotope study

Muscle potassium (K+) content decreases during exercise. Previous studies, in humans, have used measurements of arteriovenous plasma potassium concentration differences (AV delta[K+]) and/or muscle biopsy to measure the loss of muscle K+ during exercise. In the current study a non-invasive method was developed to measure skeletal muscle K+ before and after exercise, using an isotope of K+, potassium-43 (43K+). Twelve subjects performed single-leg extension exercise for 2 h at 50% of their maximum predicted heart rate. The level of radioactivity from the quadriceps femoris was determined before exercise and during two periods post-exercise. After correction for counts arising outside the exercised muscle, we estimate a decrease in muscle K+ content of 3.2 +/- 1.55% (mean +/- S.E.M.) following exercise. The muscle K+ was not restored following 75 min of recovery. The decrease in muscle K+ following exercise in our study is considerably less than that suggested by previous studies using AV delta[K+] measurements but not so dissimilar from results obtained using muscle biopsy. We conclude that a small but significant loss of K+ occurs following prolonged dynamic exercise, and that complete recovery of muscle K+ is slow.

Laparoscopic anterior resection of the rectum using a triple stapled intracorporeal anastomosis in the pig

Laparoscopic anterior resection of the rectum was performed in the porcine model. Colorectal anastomosis was accomplished with a closed triple staple technique using a circular stapler. The anvil and shaft were passed beyond the level of resection and retrieved through the proximal transverse linear cutter staple line. The stapler post was passed through the distal rectal staple line transanally. The resulting stapled anastomosis contained portions of three staple lines. There were no anastomotic leaks or strictures at one month follow-up autopsy. The triple-stapled anastomosis via a laparoscopic approach after an anterior resection of the rectum in a pig is a safe, reliable technique.

Anesthesia for laparoscopic cholecystectomy. Is nitrous oxide contraindicated?

Since it has been suggested that the use of nitrous oxide (N2O) may contribute to bowel distention, we evaluated the effects of N2O on operating conditions during laparoscopic cholecystectomy in 50 healthy patients using a double-blind protocol design. All patients received the same preanesthetic medication (midazolam, 2 mg intravenously) and induction of anesthesia consisted of intravenously administered fentanyl 1.5 micrograms.kg-1, thiopental 4-6 mg.kg-1, and a nondepolarizing muscle relaxant. For maintenance of anesthesia, patients were randomly assigned to one of two treatment groups: group 1 (n = 26) received isoflurane with 70% N2O in oxygen (O2), whereas group 2 (n = 24) received isoflurane in an air/O2 mixture. The surgeon (blinded to the anesthetic technique) estimated the degree of technical difficulty before beginning the operation using a five-point scale. At 15-min intervals throughout the operation, the surgeon was asked to evaluate both "overall operating conditions" and degree of "bowel distension" using independent five-point scales. At the end of the operation, the surgeon was asked whether or not N2O had been used as part of the anesthetic technique. There were no significant intraoperative differences between the two groups with respect to operating conditions or bowel distension. More importantly, there was no time-related change in either variable during the course of the operation. Finally, the incidence of postoperative nausea and vomiting was similar in both treatment groups. The surgeon was able to correctly determine that N2O had been administered only 44% of the time. Thus, N2O had no clinically apparent deleterious effects during laparoscopic cholecystectomy.

Association of atrophy of the medial temporal lobe with reduced blood flow in the posterior parietotemporal cortex in patients with a clinical and pathological diagnosis of Alzheimer's disease

A combination of medial temporal lobe atrophy, shown by computed tomography, and reduced blood flow in the parietotemporal cortex, shown by single photon emission tomography, was found in 86% (44/51) of patients with a clinical diagnosis of senile dementia of the Alzheimer type (SDAT). The same combination of changes was found in four out of 10 patients with other clinical types of dementia and in two out of 18 with no evidence of cognitive deficit. Of the 12 patients who died, 10 fulfilled histopathological criteria for Alzheimer's disease, nine of them having a clinical diagnosis of SDAT, and one a clinical diagnosis of multi-infarct dementia. All 10 patients with histopathologically diagnosed Alzheimer's disease had shown a combination of hippocampal atrophy and reduced parietotemporal blood flow in life. In 10 patients (nine with SDAT) out of 12 in whom the hippocampal atrophy was more noticeable on one side of the brain than on the other the parietotemporal perfusion deficit was also asymmetrical, being greater on the side showing more hippocampal atrophy. These results suggest that the combination of atrophy of the hippocampal formation and reduced blood flow in the parietotemporal region is a feature of dementia of the Alzheimer type and that the functional change in the parietotemporal region might be related to the loss of the projection neurons in the parahippocampal gyrus that innervate this region of the neocortex.

Effects of the faecal stream and stasis on the ileal pouch mucosa

This study aimed to investigate the effects of the faecal stream and stasis on the mucosa of ileal pouches. Nine patients were followed up. Two pouch biopsy specimens were obtained from each at the time of pouch formation, ileostomy closure, and three, six, and 12 months after operation. None developed pouchitis. Two pouch biopsy specimens each were also obtained from 20 patients (six with pouchitis), whose pouches had been functioning for at least a year and in whom pouch evacuation was assessed by radioisotope labelled artificial stool. Biopsy specimens were assessed for the degree of acute and chronic inflammation, mucin type (high iron diamine-alcian blue stain), a morphometric index of villous atrophy (villous height:total mucosal thickness), and crypt cell proliferation (using the monoclonal antibody Ki67). Mean values from the two biopsy specimens were obtained for each parameter. After three months of pouch function, the scores for acute and chronic inflammation, the degree of sulphomucin, and crypt cell proliferation were significantly higher, and the index of villous atrophy was significantly lower (indicating a greater degree of villous atrophy), than at pouch formation or at ileostomy closure. The values at pouch formation and ileostomy closure were similar. For all parameters, the changes seen at six and 12 months were not significantly different from those at three months. There was no significant correlation between the efficiency of pouch evacuation and any of the mucosal changes. It is concluded that exposure to the faecal stream is necessary for changes to take place in the pouch mucosa, although the amount of stasis, as measured by radioisotopic evacuation studies, seems to be irrelevant. The mucosal changes occur soon after ileostomy closure and then remain stable for at least one year.

Clinical and functional outcome after restorative proctocolectomy

Restorative proctocolectomy and ileal pouch-anal anastomosis (IPAA) has been carried out on 88 patients since 1982. Three different pouch designs (J, S and W) were used. Ten pouches had to be removed. Detailed analysis was performed on 61 patients (J = 23, S = 15, W = 23) whose pouches had been functioning for at least 6 months. There was no significant difference in surgical complications before or after ileostomy closure between pouch designs but the hospital stay was greater after construction of an S pouch (P less than 0.05). There were no significant differences in stool frequency, degree of continence or urgency between the three types. Twelve patients with J pouches required antidiarrhoeal medication compared with only one with S and five with W pouches. Only seven patients with S pouches could defaecate spontaneously compared with 22 with W pouches and all patients with J pouches (P less than 0.001). Twenty-five of 29 patients who had preservation of the anal transition zone had perfect continence compared with 23 of 32 with a mucosal proctectomy (P = n.s.). Pouchitis occurred in 13 patients, all of whom had ulcerative colitis. In a subgroup of 23 patients, pouch evacuation was assessed scintigraphically. There was no difference in pouch capacity or total volume evacuated, but spontaneous evacuation was better in J and W pouches compared with S pouches.

Effect of central cholinergic stimulation on regional cerebral blood flow in Alzheimer disease

Patients with Alzheimer disease (AD) had reduced regional cerebral blood flow (rCBF) in the posterior parietotemporal region compared with controls, as determined with technetium-99m hexamethyl propyleneamine oxime and single photon emission tomography. Central cholinergic stimulation with physostigmine produced a focal increase in rCBF in the posterior parietotemporal region in the patients with AD but not in controls.

Single-photon emission computerised tomography (SPECT) in schizophrenia

SPECT studies were carried out on three occasions in a woman with schizophrenia. Marked 'hypofrontality' was demonstrated during an acute phase of illness. A study during remission was within normal limits, but some return of the original defect was noted in a subsequent relapse. These findings parallel those found in PET studies of schizophrenia.

Iodine-131 meta-iodobenzylguanidine (131I-MIBG) for the localization of suspected phaeochromocytoma

Forty-five 131I-MIBG scintigrams were performed in 42 patients with suspected phaeochromocytoma. Two patients were infants and the remainder were adults. A sensitivity of 81.8% and a specificity of 88.2% were achieved, leading to an accuracy of 86.7%. The positive predictive value was 69.2% and the negative predictive value was 93.7%.

Five patients with Rasmussen's syndrome investigated by single-photon-emission computed tomography

Five patients with Rasmussen's syndrome (sometimes known as smouldering encephalitis), are presented. This rare form of childhood epilepsy is characterized by intractable partial seizures with progressive neurological and mental impairment. Diagnostic brain biopsy shows the histological changes of active encephalitis, consistent with a viral infection. Although the raised cerebrospinal fluid (CSF) complement and interferon levels seen in some patients support this hypothesis, no infective agent has yet been isolated. All five patients were investigated by transmission computed tomography (CT) of the head, electroencephalography (EEG) and cerebral single-photon-emission computed tomography (SPECT) using 99Tcm-hexamethylpropylenamine oxime (HMPAO) and in addition 123I-amphetamine (IMP) in Patient 1. 99Tcm-HMPAO is now regarded as reflecting cerebral perfusion, whereas the uptake of 123I-amphetamine is more dependent on cell function. In all patients SPECT imaging demonstrated an area of hypoperfusion/hypometabolism which corresponded to the anatomical localization of the epiletogenic foci found by clinical assessment, EEG and CT. In all cases the SPECT study also demonstrated a more extensive area of abnormality than CT, and in the two patients who had sequential studies, alteration in the size of the defect was found which correlated with the patients' changing clinical condition. SPECT imaging in Rasmussen's syndrome may facilitate anatomical localization of the area of pathology, and may demonstrate a changing pattern in cerebral hypoperfusion/hypometabolism. It could also serve as a guide to accurate brain biopsy.