Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass at 5 years (YOMEGA): a prospective, open-label, non-inferiority, randomised extension study

BACKGROUND

The multicentre randomised trial YOMEGA (NCT02139813) comparing the one anastomosis gastric bypass (OAGB) with the Roux-en-Y gastric bypass (RYGB) confirmed the non-inferiority of OAGB on weight loss outcomes at 24 months. We aimed to report weight loss, metabolic, and safety outcomes at 5 years.

METHODS

YOMEGA is a prospective, open-label, non-inferiority, randomised trial conducted at nine centres in France. Inclusion criteria were BMI of 40 kg/m2 or more, or 35 kg/m2 or more with comorbidities. Key exclusion criteria were severe gastro-oesophageal reflux disease or Barrett's oesophagus and previous bariatric surgery. Patients were randomly assigned (1 :1) to OAGB (one gastrojejunal anastomosis with a 200 cm biliopancreatic limb) or RYGB (with a 150 cm alimentary limb and a 50 cm biliary limb), stratified by centre, with blocks of variable size. The primary endpoint of this extension study was percentage excess BMI loss and was analysed in the per-protocol population, including patients with data who were operated on with the technique randomly assigned to them and excluding patients with major deviations from the protocol during the follow-up (change of surgical technique, death, or withdrawal of consent). Non-inferiority was concluded for the primary endpoint if the upper bound of the CI was less than the non-inferiority limit (7 percentage points). YOMEGA is registered with ClinicalTrials.gov, NCT02139813, and the 5-year follow-up of YOMEGA is registered with ClinicalTrials.gov, NCT05549271.

FINDINGS

Between May 13, 2014, and March 2, 2016, 253 patients were randomly assigned to OAGB (n=129) or RYGB (n=124), and from these patients 114 in the OAGB group and 118 in the RYGB group were included in the per-protocol analysis. In the per-protocol population, at baseline, mean age was 43·0 years (SD 10·8), mean BMI was 44·0 kg/m2 (5·6), 54 (23%) patients were male and 178 (77%) were female; 55 (27%) of 207 patients had type 2 diabetes. After 5 years, mean percentage excess BMI loss was -75·6% (SD 28·1) in the OAGB group versus -71·4% (SD 29·8) in the RYGB group, confirming non-inferiority (mean difference -4·1% [90% CI -12·0 to 3·7], p=0·0099). Remission of type 2 diabetes was similar in both groups. Nutritional status did not differ; the most common adverse event was clinical gastro-oesophageal reflux disease, occurring in 27 (41%) of 66 patients in the OAGB group versus 14 (18%) of 76 patients in the RYGB group (p=0·0030). Among serious adverse events, ten (8%) of 127 patients converted from OAGB to RYGB. 171 (68%) of 253 patients were followed up.

INTERPRETATION

OAGB was not inferior to RYGB regarding percentage excess BMI loss at 5 years with similar metabolic outcomes. The high rate of clinical gastro-oesophageal reflux disease after OAGB raises questions about its long-term consequences, which need to be further investigated.

FUNDING

Medtronic.

Bariatric surgery short-term outcomes in patients with obstructive sleep apnoea: the Severe Obesity Outcome Network prospective cohort

BACKGROUND/OBJECTIVES

Although the benefits of bariatric surgery have been clearly established, it is not known whether they are as important in patients with obstructive sleep apnoea (OSA). Primary aim: to evaluate whether patients with moderate-to-severe OSA (apnoea-hypopnea index (AHI) ≥ 15 events/h) treated by continuous positive airway pressure/non-invasive ventilation (median [IQR] adherence 6.5 h/night [5; 7.9] at baseline) lose the same amount of body weight 1 year after bariatric surgery as patients with no or mild OSA. Secondary objectives: to compare the evolution of type 2 diabetes and hypertension after bariatric surgery, and surgical complication rates between groups.

METHODS/SUBJECTS

Analyses were performed in 371 patients included in a prospective cohort of bariatric surgery, the Severe Obesity Outcome Network cohort. Subjects having moderate-to-severe OSA (n = 210) at baseline were compared with other subjects (n = 161).

RESULTS

Excess weight loss (%EWL) at 1 year was lower in patients with moderate-to-severe OSA than in patients without (64.9%EWL [46.9; 79.5] vs. 73.8%EWL [56.6; 89.3], p < 0.01). Multivariable analysis showed that age, initial body mass index and type of surgery, but not OSA status, were associated with 1-year %EWL. Diabetes remitted in 25 (41%) patients with moderate-to-severe OSA and 16 (48%) patients with no or mild OSA (p = 0.48). Hypertension remitted in 28 (32.9%) patients with moderate-to-severe OSA and 9 (40.9%) with no or mild (p = 0.48). Complication rates were 28 (13.3%) in patients with moderate-to-severe OSA and 12 (7.5%) in patients with no or mild OSA (p = 0.07).

CONCLUSIONS

Patients with OSA lose less body weight after bariatric surgery. This was related to older age and a higher baseline body mass index. However, the improvements of diabetes and hypertension were similar to that of patients without OSA, and the risk of surgical complications was not higher.

Decision Tree for the Performance of Intraoperative Liver Biopsy During Bariatric Surgery

BACKGROUND AND AIMS

Bariatric surgery provides a useful opportunity to perform intraoperative liver biopsy to screen for non-alcoholic steatohepatitis (NASH). There is currently no consensus on whether intraoperative liver biopsy should be systematically performed. The aim of this study was to develop and validate a decision tree to guide that choice.

APPROACH AND RESULTS

This prospective study included 102 consecutive patients from the severe obesity outcome network (SOON) cohort in whom liver biopsy was systematically performed during bariatric surgery. A classification and regression tree (CART) was created to identify the nodes that best classified patients with and without NASH. External validation was performed. Seventy-one biopsies were of sufficient quality for analysis (median body mass index 43.3 [40.7; 48.0] kg/m²). NASH was diagnosed in 32.4% of cases. None of the patients with no steatosis on ultrasound had NASH. The only CART node that differentiated between a "high-risk" and a "low-risk" of NASH was alanine aminotransferase (ALT). ALT>53IU/L predicted NASH with a positive predictive value (PPV) of 68% and a negative predictive value (NPP) of 89%, a sensitivity of 77%, and a specificity of 84%. In the external cohort (n=258), PPV was 68%, NPV was 62%, sensitivity was 27%, and specificity was 90%.

CONCLUSIONS

The present work supports intraoperative liver biopsy to screen for NASH in patients with ALT>53IU/L; however, patients with no steatosis on ultrasound should not undergo biopsy. The CART failed to identify an algorithm with a good sensitivity to screen for NASH in patients with ultrasonography-proven steatosis and ALT≤53IU/L.

Effectiveness and Safety of Bariatric Surgery in Patients with End-Stage Chronic Kidney Disease or Kidney Transplant

OBJECTIVE

This study aimed to evaluate (1) the effectiveness, complications, and postoperative access to transplantation in end-stage chronic kidney disease (ECKD) and (2) the effectiveness and complications of bariatric surgery in patients who had already undergone kidney transplant.

METHODS

A systematic review and meta-analysis of mortality and complications rates were performed. Thirty studies were reviewed.

RESULTS

After bariatric surgery, patients with ECKD had similar postoperative weight loss to patients from the general population. Meta-analysis showed post-bariatric surgery rates of 2% (95% CI: 0%-3%) for mortality and 7% (95% CI: 2%-14%) for complications. Approximately one-fifth of the patients had access to a transplant. This rate may be underestimated because of the short duration of follow-up. The lack of control groups did not allow for a conclusion on the role of bariatric surgery in facilitating access to kidney transplantation. In patients who had received a kidney transplant, bariatric surgery seemed to improve renal function but increased graft-rejection risk, possibly because of changes in the bioavailability of immunosuppressant drugs.

CONCLUSIONS

Bariatric surgery yields significant weight loss in patients with ECKD that improves patients' chances of accessing a transplant but does not guarantee it; however, the risk for complications and death is higher than in other patients. After transplantation, bariatric surgery-induced weight loss appeared to positively impact the function of the grafted kidney, but careful monitoring of immunosuppressant medications is required.

Benefits and risks of bariatric surgery in patients with bipolar disorders

The prevalence of bipolar disorders in patients requesting bariatric surgery is estimated to be 1.5% to 3.4%. There are currently no specific recommendations regarding the way bariatric surgery should be managed in the context of bipolar disorder. The aim was to document the benefit-risk of bariatric surgery in patients with bipolar disorders. A systematic literature review was carried out. In addition, results were reported from a survey of current clinical practice in French referent centers for obesity care. Finally, 3 clinical cases from the "Severe Obesity Outcome Network" cohort are described. This systematic review shows there are few studies in the literature regarding the outcomes of bariatric surgery in patients with bipolar disorders and no randomized, controlled trials. Weight loss appeared similar in all patients, but psychiatric complications were sometimes reported in those with bipolar disorders. Almost all 11 referent centers for obesity care that responded had carried out bariatric surgery in patients with stable bipolar disorders. Postsurgical psychiatric destabilization occurred and included, at least, a need to reinforce treatment and follow-up. In the 3 case studies, postsurgical manic or hypomanic decompensation occurred. Thus, although effective in terms of weight loss, bariatric surgery could be a destabilizing factor for those with bipolar disorders. Current practice is to contraindicate surgery in patients with unstable disorders. There are insufficient data to conclude on the benefits and safety of bariatric surgery in patients with stable bipolar disease. Further studies are required to fully determine the benefits and risks.

Predicting the quality of surgical exposure using spatial and procedural features from laparoscopic videos

PURPOSE : Evaluating the quality of surgical procedures is a major concern in minimally invasive surgeries. We propose a bottom-up approach based on the study of Sleeve Gastrectomy procedures, for which we analyze what we assume to be an important indicator of the surgical expertise: the exposure of the surgical scene. We first aim at predicting this indicator with features extracted from the laparoscopic video feed, and second to analyze how the extracted features describing the surgical practice influence this indicator. METHOD : Twenty-nine patients underwent Sleeve Gastrectomy performed by two confirmed surgeons in a monocentric study. Features were extracted from spatial and procedural annotations of the videos, and an expert surgeon evaluated the quality of the surgical exposure at specific instants. The features were used as input of a classifier (linear discriminant analysis followed by a support vector machine) to predict the expertise indicator. Features selected in different configurations of the algorithm were compared to understand their relationships with the surgical exposure and the surgeon's practice. RESULTS : The optimized algorithm giving the best performance used spatial features as input ([Formula: see text]). It also predicted equally the two classes of the indicator, despite their strong imbalance. Analyzing the selection of input features in the algorithm allowed a comparison of different configurations of the algorithm and showed a link between the surgical exposure and the surgeon's practice. CONCLUSION : This preliminary study validates that a prediction of the surgical exposure from spatial features is possible. The analysis of the clusters of feature selected by the algorithm also shows encouraging results and potential clinical interpretations.

Assessment of haemorrhoidal artery network using Doppler-guided haemorrhoidal artery ligation for haemorrhoids and pathogenesis implications

BACKGROUND

Some authors, either with anatomical studies or Doppler laser flowmetric investigations have shown the blood flow to the posterior midline of the anus to be potentially deficient. This relative local ischaemia might explain pathogenesis of anal fissure, which is often located posteriorly. The aim of this study was to record the exact position of the distal branches of the superior rectal artery during Doppler-guided haemorrhoidal artery ligation-rectoanal repair (HAL-RAR) procedures with special reference to posterior distribution of the arteries.

METHODS

All consecutive patients with symptomatic haemorrhoids who were treated with the HAL-RAR procedure between February 2008 and February 2014 in a single institution were included in the study. Number and position of Doppler-guided ligations were prospectively collected. Pearson's chi-squared test was used to compare artery locations.

RESULTS

A total of 150 patients (75 women) with symptomatic haemorrhoids were included in the study. Median age was 53 years (range 23-83). A median of 10 ligations were placed per patient (range 3-18). A significantly lower number of cumulative arterial ligations was recorded in the posterior position (88 ligations overall, P = 0.025).

CONCLUSIONS

The number of distal branches of the superior rectal artery that have been localized by the Doppler-guided HAL-RAR technique is lower at the posterior midline than in the other segments of the lower rectum. This is another evidence of the vascular deficiency at the posterior pole of the anal canal that might explain the pathogenesis of the anal fissure.

Efficacy and safety of one anastomosis gastric bypass versus Roux-en-Y gastric bypass for obesity (YOMEGA): a multicentre, randomised, open-label, non-inferiority trial

BACKGROUND

One anastomosis gastric bypass (OAGB) is increasingly used in the treatment of morbid obesity. However, the efficacy and safety outcomes of this procedure remain debated. We report the results of a randomised trial (YOMEGA) comparing the outcomes of OAGB versus standard Roux-en-Y gastric bypass (RYGB).

METHODS

This prospective, multicentre, randomised non-inferiority trial, was held in nine obesity centres in France. Patients were eligible for inclusion if their body-mass index (BMI) was 40 kg/m² or higher, or 35 kg/m² or higher with the presence of at least one comorbidity (type 2 diabetes, high blood pressure, obstructive sleep apnoea, dyslipidaemia, or arthritis), and were aged 18-65 years. Key exclusion criteria were a history of oesophagitis, Barrett's oesophagus, severe gastro-oesophageal reflux disease resistant to proton-pump inhibitors, and previous bariatric surgery. Participants were randomly assigned (1:1) to OAGB or RYGB, stratified by centre with blocks of variable size; the study was open-label, with no masking required. RYGB consisted of a 150 cm alimentary limb and a 50 cm biliary limb and OAGB of a single gastrojejunal anastomosis with a 200 cm biliopancreatic limb. The primary endpoint was percentage excess BMI loss at 2 years. The primary endpoint was assessed in the per-protocol population and safety was assessed in all randomised participants. This study is registered with ClinicalTrials.gov, number NCT02139813, and is now completed.

FINDINGS

From May 13, 2014, to March 2, 2016, of 261 patients screened for eligibility, 253 (97%) were randomly assigned to OAGB (n=129) or RYGB (n=124). Five patients did not undergo their assigned surgery, and after undergoing their surgery 14 were excluded from the per-protocol analysis (seven due to pregnancy, two deaths, one withdrawal, and four revisions from OAGB to RYGB) In the per-protocol population (n=117 OAGB, n=117 RYGB), mean age was 43·5 years (SD 10·8), mean BMI was 43·9 kg/m² (SD 5·6), 176 (75%) of 234 participants were female, and 58 (27%) of 211 with available data had type 2 diabetes. After 2 years, mean percentage excess BMI loss was -87·9% (SD 23·6) in the OAGB group and -85·8% (SD 23·1) in the RYGB group, confirming non-inferiority of OAGB (mean difference -3·3%, 95% CI -9·1 to 2·6). 66 serious adverse events associated with surgery were reported (24 in the RYGB group vs 42 in the OAGB group; p=0·042), of which nine (21·4%) in the OAGB group were nutritional complications versus none in the RYGB group (p=0·0034).

INTERPRETATION

OAGB is not inferior to RYGB regarding weight loss and metabolic improvement at 2 years. Higher incidences of diarrhoea, steatorrhoea, and nutritional adverse events were observed with a 200 cm biliopancreatic limb OAGB, suggesting a malabsorptive effect.

FUNDING

French Ministry of Health.

Waist, neck circumferences, waist-to-hip ratio: Which is the best cardiometabolic risk marker in women with severe obesity? The SOON cohort

A centralized deposit of adiposity increases the risk of cardiometabolic diseases. Several anthropometric markers can be used to characterize fat distribution. In the case of severe obesity, several markers, such as hip and waist circumference, are prone to measurement error. Conversely, neck circumference is easy to obtain. The aim was to determine the best surrogate marker of obesity-related cardiometabolic diseases from: body mass index (BMI), waist, hip and neck circumferences and waist-to-hip ratio.

Prevalence and Factors Associated with Helicobacter Pylori in Patients Undergoing Bariatric Surgery: the SOON Cohort

PURPOSE

Helicobacter Pylori (HP) infection is systematically screened for before carrying out bariatric surgery. Criteria to determine "at risk" patients and avoid systematic screening are lacking. We evaluated the prevalence of HP infection and associated predictive factors in a population of patients with class II and III obesity volunteering for bariatric surgery.

MATERIALS AND METHODS

Observational, cross-sectional study of patients included in the severe obesity outcome network (SOON) cohort. All patients underwent HP screening. The relationship between plasma metabolic parameters and vitamin levels, medical history and socio-economic parameters, and HP infection was analyzed.

RESULTS

Data from 201 patients, median age 43 years [IQR 35; 52] (81% female) were analyzed. Forty-four patients (22%) were infected with HP and successfully treated, most with a single course of treatment, either combined antibiotics or Pylera®. HP infection was associated with social precariousness as defined by the French "Evaluation de la Précarité et des Inégalités de santé dans les Centres d'Examens de Santé" (EPICES) score (Evaluation of Poverty and Health Inequalities in Health-Assessment Centers) (OR, 1.027; 95% CI, 1.008-1.046; p < 0.004) and with higher levels of vitamin B₁₂ (OR, 1.004; 95% CI, 1.001-1.007; p < 0.007).

CONCLUSION

The prevalence of HP infection was 22% and was associated with social precariousness. Plasma glucose/insulin and lipid/lipoprotein profiles, liver enzymes or vitamin deficiencies were not associated with HP infection. The number of characteristics associated with HP infection was insufficient to define patients who do not require HP screening before bariatric surgery.

Early experience with ambulatory robotic ventral rectopexy

OBJECTIVE OF THE STUDY

Ventral rectopexy can be performed robotically with only limited trauma for the patient, making its performance in an ambulatory setting potentially interesting. The aim of this study is to report our preliminary experience with ambulatory robotic ventral rectopexy in consecutive patients.

PATIENTS AND METHODS

Ten consecutive patients underwent robotic ventral rectopexy for total rectal prolapse (n=8) or symptomatic enterocele (n=2) between February 2014 and April 2015. Patients were selected for outpatient treatment based on criteria of patient motivation, favorable social conditions, and satisfactory general condition. Patient characteristics, technical results and cost were reported.

RESULTS

The mean operating time was 94minutes (range: 78-150). The average operating room occupancy time was 254minutes (222-339). There were no operative complications, conversion to laparotomy, or postoperative complication. The average duration of hospital stay was 11 (8-32) hours. Two patients required hospitalization: one for persistent pain and the other for urinary retention. The average maximum pain score recorded on postoperative day 1 was 2/10 on a visual analog scale (range: 0-5/10). Estimated average cost (excluding amortization of the purchase of the robot) was €9088 per procedure.

CONCLUSIONS

Ambulatory management of robotic ventral rectopexy is feasible and safe.

Treatment Discontinuation Following Bariatric Surgery in Obstructive Sleep Apnea: a Controlled Cohort Study

BACKGROUND

Uncontrolled studies looking at the discontinuation of obstructive sleep apnea (OSA) treatment after bariatric surgery (BS) have suggested that surgery improves OSA. However, this discontinuation of OSA treatment by BS patients has never been compared to a matched population without BS. The objectives of this study are to evaluate whether BS increases OSA treatment discontinuation compared to that in matched patients without BS and to identify predictive factors of OSA treatment discontinuation in BS patients. The study took place in an ambulatory, tertiary hospital.

METHODS

We included 61 OSA patients who underwent BS in a retrospective controlled cohort study. The computerized matching procedure included age, sex, body mass index, year of starting OSA treatment, treatment type, and duration selected 59 controls matched to 28 patients with BS. The main outcome was OSA treatment discontinuation within 2 years after BS.

RESULTS

Patients with BS stopped OSA treatment more often than controls, usually between 6 months and 1 year after BS: hazards ratio (HR (95 %, CI)) 15.93 (3.29, 77.00). Before 6 months or beyond 1 year after BS, treatment discontinuation was not different between BS patients and controls. In univariate analyses, female gender, absence of co-morbidities, greater weight loss, and lower baseline OSA severity were associated with stopping OSA treatment after BS. No factor remained independently associated in multivariate analysis.

CONCLUSIONS

Apneic patients having BS stop OSA treatment more than matched controls. Treatment discontinuation may be attributed to recovery or to abandonment. The effect of BS on OSA may have been overestimated in uncontrolled BS studies that ignored basal OSA treatment discontinuation in routine clinical practice.

Malnutrition after bariatric surgery

BACKGROUND

Malnutrition is a rare but severe complication following obesity surgery. Our objective was to analyze these cases of malnutrition and their management at the Grenoble University Hospital.

METHODS

Retrospective data between 2006 to 2016 was analyzed from Department of Medical Information, Severe Obesity Outcome Network, and register of the Department of Artificial Nutrition. Data collected concerned age, sex, anthropometric data, surgical procedures and history of obesity surgery, initial surgical follow-up, delay from surgery, nutritional characteristics, nutritional and surgical management, follow-up and outcomes.

RESULTS

Six patients had protein malnutrition after obesity surgery. Five patients (N.=5/6 83%) were initially operated on in other establishments. Only 1 patient in the cohort of 484 patients operated at on our institution was suffering from malnutrition (N.=1/484, 0.2%). All patients showed an excess weight loss of over 100%. Albumin level averaged 24.8 g/L at time of diagnosis. Patients were mainly operated on for an omega bypass (N.=4/6, 66%). Delay of malnutrition was 17.25 months in this category of patients whereas it was 84 months in patients having been operated on by another intervention. 3 patients (i.e. 50%) had chronic kidney disease when their initial surgery was performed. Two patients presented acute idiopathic pancreatitis following obesity surgery.

CONCLUSIONS

Patients are at risk of malnutrition, especially after omega bypass and in patients with chronic kidney disease. Occurrence of acute pancreatitis is an alert to the risk of malnutrition.

Day case robotic ventral rectopexy compared with day case laparoscopic ventral rectopexy: a prospective study

BACKGROUND

Ventral rectopexy to the promontory has become one of the most strongly advocated surgical treatments for patients with full-thickness rectal prolapse and deep enterocele. Despite its challenges, laparoscopic ventral rectopexy with or without robotic assistance for selected patients can be performed with relatively minimal patient trauma thus creating the potential for same-day discharge. The aim of this prospective case-controlled study was to assess the feasibility, safety, and cost of day case robotic ventral rectopexy compared with routine day case laparoscopic ventral rectopexy.

METHODS

Between February 28, 2014 and March 3, 2015, 20 consecutive patients underwent day case laparoscopic ventral rectopexy for total rectal prolapse or deep enterocele at Michallon University Hospital, Grenoble. Patients were selected for day case surgery on the basis of motivation, favorable social circumstances, and general fitness. One out of every two patients underwent the robotic procedure (n = 10). Demographics, technical results, and costs were compared between both groups.

RESULTS

Patients from both groups were comparable in terms of demographics and technical results. Patients operated on with the robot had significantly less pain (p = 0.045). Robotic rectopexy was associated with longer median operative time (94 vs 52.5 min, p < 0.001) and higher costs (9088 vs 3729 euros per procedure, p < 0.001) than laparoscopic rectopexy.

CONCLUSIONS

Day case robotic ventral rectopexy is feasible and safe, but results in longer operative time and higher costs than classical laparoscopic ventral rectopexy for full-thickness rectal prolapse and enterocele.

Anterior rectopexy for full-thickness rectal prolapse: Technical and functional results

AIM: To assess effectiveness, complications, recurrence rate, and recent improvements of the anterior rectopexy procedure for treatment of total rectal prolapse.

METHODS: MEDLINE, PubMed, EMBASE, and other relevant database were searched to identify studies. Randomized controlled trials, non-randomized studies and original articles in English language, with more than 10 patients who underwent laparoscopic ventral rectopexy for full-thickness rectal prolapse, with a follow-up over 3 mo were considered for the review.

RESULTS: Twelve non-randomized case series studies with 574 patients were included in the review. No surgical mortality was described. Conversion was needed in 17 cases (2.9%), most often due to difficult adhesiolysis. Twenty eight patients (4.8%) presented with major complications. Seven (1.2%) mesh-related complications were reported. Most frequent complications were urinary tract infection and urinary retention. Mean recurrence rate was 4.7% with a median follow-up of 23 mo. Improvement of constipation ranged from 3%-72% of the patients and worsening or new onset occurred in 0%-20%. Incontinence improved in 31%-84% patients who presented fecal incontinence at various stages. Evaluation of functional score was disparate between studies.

CONCLUSION: Based on the low long-term recurrence rate and favorable outcome data in terms of low de novo constipation rate, improvement of anal incontinence, and low complications rate, laparoscopic anterior rectopexy seems to emerge as an efficient procedure for the treatment of patients with total rectal prolapse.

[Colo-rectal surgery, through laparoscopic approach. Considerations concerning a personal experience of 613 cases]

The start of colo-rectal laparoscopic surgery, after an initial period of enthusiasm tempered by predictable technical difficulties, was finally slowed down by the risk of port site metastases. However, this kind of surgery continued to be used for benign colonic pathology, allowing the achievement of surgical skill. Some well-trained teams reported comparable loco-regional relapse rate and 5-years survival in both laparoscopic and conventional trials. The some good results concern also mortality and morbidity in both kind of trials. Based on 613 personal cases, the authors reveal this surgery's peculiarities, justifying a predictable development.

[Critical analysis of the laparoscopic approach in colorectal surgery based on the personal experience of 613 interventions]

Initial experience of colo-rectal laparoscopic surgery, after a period of enthusiasm tempered by anticipated technical difficulties, was held back due to reservations made in the case of operations for cancer, following the publication warning surgeons concerning the danger of the development of port-site metastasis. Nevertheless, this type of surgery continued to be developed for benign diseases of the colon, enabling acquiring of the necessary surgical skill. This skill could then applied by experienced surgical teams for the treatment of cancer, that do not seem to show negative aspects, in connection with local recurrences or 5 years survival rates. These reports need to be confirmed by ongoing multi-center trials currently being undertaken in several countries. The advantages of laparoscopic surgery in terms of post-operative comfort having been widely demonstrated, it seems that as applied strictly to colo-rectal pathologies, morbidity and mortality of this surgical procedure are at least equal to those of conventional "open" surgery. These good results require, however, a relatively long period of training. Based on the experience of 613 patients operated by laparoscopic surgery, the authors highlight the special characteristics of this surgical technique whose future expansion can be expected and is justified.

Determination of aromatic amines formed from azo colorants in toy products

A study for the determination of the aromatic amines formed after reduction of the azo colorants mostly used in toys was conducted. Sodium dithionite was used in the reductive cleavage of the azo group for the dyes, and the released amines were subsequently analysed by high-performance liquid chromatography with UV detection. The influence of different variables related to the reduction process was investigated by the use of a full-level factorial design, where most significant parameters as well as order interactions were studied. Reduction profiles for each colorant were obtained by studying the changes in the amount of amine obtained with different dithionite/colorant ratios. The expected aromatic amines forming azo colorants were detected, and in the presence of a nitro group a further reduction was observed. The yield of the total reduction process was determined by using standard addition of different quantities of amines to the colorants.

Determination of N-nitrosamines in latex by sequential supercritical fluid extraction and derivatization

A new method to determine N-nitrosamines in latex products has been developed by combination of supercritical fluids and chemical derivatization. A new design for a liquid trap has been introduced. A factorial fractional design was used in order to evaluate the influence of the different factors affecting the process. Factors such as pressure, temperature, static and dynamic time, restrictor temperature and volume of an hydrobromic acid-acetic anhydride mixture (1:10, v/v) were included in the design. CO2 was used as the extraction fluid. Gas chromatography with nitrogen and phosphorus sensitive detection was employed to achieve good sensitivity attending to the molecular structure of these compounds (N-nitrosamines and their corresponding secondary amines). The obtained results have shown to be useful to increase selectivity and reduce sample handling.

Optimization of the extraction of azo colorants used in toy products

Azo dyes are widely used in formulations intended for children use. But their potential toxicity raised the need of an efficient and fast method of analysis. A study for the optimization of the extraction of some azo colorants used in toys was conducted. Several extraction methods for the selected analytes were evaluated and compared, i.e., supercritical fluid extraction (SFE), microwave-assisted extraction (MAE) and Soxhlet extraction. Poly(vinyl chloride) samples spiked with known quantities of the studied dyes were prepared. The influence of critical variables on analyte recoveries in SFE and MAE was investigated by using a full-level factorial design, where most significant parameters as well as order interactions were studied in each case. The analytes were subsequently detected by high-performance liquid chromatography with UV detection. The three extraction techniques were compared in terms of reproducibility, selectivity and analyte recoveries. MAE showed higher recoveries (above 98%), except for the diazo dye (nearly 60%). Reproducibilities were generally good for the three methods (relative standard deviation lower than 2.0%).

Optimization of parameters for the analysis of aromatic amines in finger-paints

A study for the optimisation of the supercritical fluid extraction (SFE) of some aromatic amines (4-chloro-o-toluidine, 2-naphthylamine, 4-aminobiphenyl and benzidine) in finger-paints was conducted. The influence of different variables related to the technique on recoveries was investigated. The analytes were subsequently analysed by gas chromatography after SFE. The study allowed the estimation of four main factors (temperature, pressure, static time and volume of modifier) on recoveries by the use of a two-level factor design, where most significant parameters as well as second- and third-order interactions were identified. Other factors, such as type and volume of modifier and time of contact between the spiker solution and the sample prior to extraction, were also studied. The influence of matrix on extraction recovery was also evaluated by applying the method to different finger-paints, and recoveries were similar or even higher in some cases. The drying process of samples was also studied, while classical drying in an oven and microwaves were compared, with similar efficiencies in both methods. The method was validated by extracting the aromatic amines from some commercial finger-paints.

Simultaneous supercritical fluid derivatization and extraction of formaldehyde by the Hantzsch reaction

A study where the Hantzsch reaction is used to produce the chemical derivatization of formaldehyde in a supercritical medium is presented in this paper. Pressure, temperature and other parameters such as static and dynamic extraction time must be optimized to increase the yield of this kinetically controlled reaction. A 2(5-1) (resolution V) factorial design was used to study the significant parameters affecting the supercritical process in terms of resolution and sensitivity. A subsequent central composite design was employed to find the conditions of maximum response. Ultraviolet-visible spectrophotometry was used as the detection technique. The optimum conditions were used for the determination of formaldehyde in real finger-paints by means of the previous addition of known quantities of this analyte to the paint. Results were compared with those obtained with supercritical fluid extraction and subsequent chemical derivatization and an improvement of sensitivity as well as a reduction of time of analysis, solvent waste and reagents consumption were observed.

Determination of some aromatic amines in finger-paints for children's use by supercritical fluid extraction combined with gas chromatography

A test method based on supercritical fluid extraction (SFE) and gas chromatography has been developed for some aromatic amines, such as 4-chloro-o-toluidine, beta-naphthylamine and 4-aminobiphenyl. A two-level factor design was used as the optimization procedure. Four main variables were considered: CO2 pressure, extraction temperature, static extraction time and volume of modifier (methanol). Results obtained for 4-chloro-o-toluidine, indicated that the volume of modifier was the variable with the most important influence on extraction, CO2 pressure had a negative effect and temperature and time were less significant. For the other amines, static time was the most important variable in both cases, followed by CO2 pressure and volume of modifier, with no influence of temperature. SFE was compared with Soxhlet extraction, and was found to give higher recoveries in all cases. Other commercial finger-paints were tested for the presence of aromatic amines.