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Dive into the research topics where Markus K. Müller is active.

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Featured researches published by Markus K. Müller.


The Lancet | 2003

Obesity in general elective surgery

Daniel Dindo; Markus K. Müller; Markus Weber; Pierre-Alain Clavien

Summary Background Obese patients are generally believed to be at a higher risk for surgery than those who are not obese, although convincing data are lacking. Methods We prospectively investigated a cohort of 6336 patients undergoing general elective surgery at our institution to assess whether obesity affects the outcome of surgery. Exclusion criteria were emergency, vascular, thoracic, and bariatric operations; transplantation procedures; patients under immunosuppression; and operations done under local anaesthesia. Postoperative morbidity was analysed for non-obese and obese patients (body-mass index 2 vs 3=30 kg/m 2 ). Obesity was further stratified into mild obesity (30·0–34·9 kg/m 2 ) and severe obesity (⩾35kg/m 2 ). Risk factors were analysed with univariate and multivariate models. Findings The cohort consisted of 6336 patients, of whom 808 (13%) were obese, 569 (9%) were mildly obese, and 239 (4%) had severe obesity. The morbidity rates in patients who were obese compared with those who were not were much the same (122 [15·1%] of 808 vs 901 [16·3%] of 5528; p=0·26), with the exception of an increased incidence of wound infections after open surgery in patients who were obese (17 [4%] of 431 vs 92 [3%] of 3555, p=0·03). Incidence of complications did not differ between patients who were mildly obese (91 [16·0%] of 569), severely obese (36 [15·1%] of 239), and non-obese (901 [16·3%] of 5528; p=0·19). In multivariate regression analyses, obesity was not a risk factor for development of postoperative complications. Of note, the additional medical resource use as estimated by a new classification of complications showed no differences between patients who were and were not obese. Interpretation Obesity alone is not a risk factor for postoperative complications. The regressive attitude towards general surgery in obese patients is no longer justified.


Annals of Surgery | 2004

Laparoscopic gastric bypass is superior to laparoscopic gastric banding for treatment of morbid obesity.

Markus Weber; Markus K. Müller; Tanja Bucher; Stefan Wildi; Daniel Dindo; Fritz Horber; Rennward Hauser; Pierre-Alain Clavien

Objective:To define whether laparoscopic gastric banding or laparoscopic Roux-en-Y gastric bypass represents the better approach to treat patients with morbid obesity. Summary Background Data:Two techniques, laparoscopic gastric bypass or gastric banding, are currently widely used to treat morbid obesity. Since both procedures offer certain advantages, a strong controversy exists as to which operation should be proposed to these patients. Therefore, data are urgently needed to identify the best therapy. Methods:Since randomized trials are most likely not feasible because of the highly different invasiveness and irreversibility of these procedures, a matched-pair design of a large prospectively collected database appears to be the best method. Therefore, we used our prospective database including 678 bariatric procedures performed at our institution since 1995. A total of 103 consecutive patients with laparoscopic gastric bypass were randomly matched to 103 patients with laparoscopic gastric banding according to age, body mass index, and gender. Results:Both groups were comparable regarding age, gender, body mass index, excessive weight, fat mass, and comorbidites such as diabetes, heart disease, and hypertension. Feasibility and safety: All gastric banding procedures were performed laparoscopically, and one gastric bypass operation had to be converted to an open procedure. Mean operating time was 145 minutes for gastric banding and 190 minutes for gastric bypass (P < 0.001). Hospital stay was 3.3 days for gastric banding and 8.4 days for gastric bypass. The incidence of early postoperative complications was not significantly different, but late complications were significantly more frequent in the gastric banding group (pouch dilatation). There was no mortality in both groups. Efficiency: Body mass index decreased from 48.0 to 36.8 kg/m2 in the gastric banding group and from 47.8 to 31.9 kg/m2 in the gastric bypass group within 2 years of surgery. These differences became significant from the first postoperative month until the end of the follow-up (24 months). The gastric bypass procedure achieved a significantly better reduction of comorbidities. Conclusions:Laparoscopic gastric banding and laparoscopic gastric bypass are feasible and safe. Pouch dilatations after gastric banding are responsible for more late complications compared with the gastric bypass. Laparoscopic gastric bypass offers a significant advantage regarding weight loss and reduction of comorbidities after surgery. Therefore, in our hands, laparoscopic Roux-en-Y gastric bypass appears to be the therapy of choice.


Annals of Surgery | 2003

Laparoscopic Roux-en-Y gastric bypass, but not rebanding, should be proposed as rescue procedure for patients with failed laparoscopic gastric banding.

Markus Weber; Markus K. Müller; Jean-Marie Michel; Rahim Belal; Fritz Horber; Renward Hauser; Pierre-Alain Clavien

Objective: To define whether laparoscopic rebanding or Roux-en-Y gastric bypass represents the best approach for failed laparoscopic gastric banding in patients with morbid obesity. Summary Background Data: Countless laparoscopic gastric bandings have been implanted during the recent years worldwide. Despite excellent short-term results, long-term failures and complications have been reported in more than 20% of patients. Which rescue procedures should be used remains controversial. Therefore, we analyzed our experience with the use of laparoscopic rebanding versus laparoscopic Roux-en-Y gastric bypass after failed gastric banding. Methods: Using a prospectively collected database, we analyzed the feasibility, safety, and effectiveness of laparoscopic rebanding versus laparoscopic conversion to Roux-en-Y gastric bypass after failed laparoscopic gastric banding. Results: A total of 62 consecutive patients were treated in our institution between May 1995 and December 2002 for failed primary laparoscopic gastric banding, including 30 laparoscopic rebandings and 32 laparoscopic conversions to Roux-en-Y gastric bypass. Rebandings were preferably done during the initial period of the study and Roux-en-Y gastric bypass in the last period. Both groups were comparable before the initial banding procedures. At the time of redo surgery, patients receiving a gastric bypass had more esophageal dysmotility (47% vs. 7%, P = 0.002) and higher body mass index (BMI) than those elected for rebanding procedures (BMI 42.0 vs. 38.4 kg/m2, P = 0.015). Feasibility and safety: Each procedure was performed laparoscopically. Mean operating time was 215 minutes for gastric bypass and 173 minutes for rebanding (P = 0.03). Early complications occurred in one case in the rebanding group and in 2 cases in the bypass group; all underwent a laparoscopic reexploration without the need for open surgery. There was no mortality in this series. Effectiveness: BMI in the gastric bypass group decreased from 42.0 to 31.8 kg/m2 (P = 0.02) within 1 year of surgery, while it remained unchanged in the rebanding group. Conclusions: Laparoscopic conversion to a gastric bypass as well as laparoscopic rebanding are feasible and safe. Conversion to gastric bypass offers a significant advantage in terms of further weight loss after surgery. Therefore, this procedure should be considered as the rescue therapy of choice after a failed laparoscopic gastric banding.


Annals of Surgery | 2011

The Impact of Complications on Costs of Major Surgical Procedures: A Cost Analysis of 1200 Patients

René Vonlanthen; Ksenija Slankamenac; Stefan Breitenstein; Milo A. Puhan; Markus K. Müller; Dieter Hahnloser; Dimitri Hauri; Rolf Graf; Pierre-Alain Clavien

Objective:To assess the impact of postoperative complications on full in-hospital costs per case. Background:Rising expenses for complex medical procedures combined with constrained resources represent a major challenge. The severity of postoperative complications reflects surgical outcomes. The magnitude of the cost created by negative outcomes is unclear. Patients and MethodsMorbidity of 1200 consecutive patients undergoing major surgery from 2005 to 2008 in a tertiary, high-volume center was assessed by a validated, complication score system. Full in-hospital costs were collected for each patient. Statistical analysis was performed using a multivariate linear regression model adjusted for potential confounders. Results:This study population included 393 complex liver/bile duct surgeries, 110 major pancreas operations, 389 colon resections, and 308 Roux-en-Y gastric bypasses. The overall 30-day mortality rate was 1.8%, whereas morbidity was 53.8%. Patients with an uneventful course had mean costs per case of US


Surgery | 2009

The correlation of nutrition risk index, nutrition risk score, and bioimpedance analysis with postoperative complications in patients undergoing gastrointestinal surgery.

Marc Schiesser; Philipp Kirchhoff; Markus K. Müller; Markus Schäfer; Pierre-Alain Clavien

27,946 (SD US


Transplantation | 2010

Donor-specific antibody levels and three generations of crossmatches to predict antibody-mediated rejection in kidney transplantation.

Sebastian Riethmüller; Sylvie Ferrari-Lacraz; Markus K. Müller; Dimitri A. Raptis; Karine Hadaya; Barbara Rüsi; Guido F. Laube; Gregory Schneiter; Thomas Fehr; Jean Villard

15,106). Costs increased dramatically with the severity of postoperative complications and reached the mean costs of US


Obesity Surgery | 2005

Laparoscopic Pouch Resizing and Redo of Gastro-jejunal Anastomosis for Pouch Dilatation following Gastric Bypass

Markus K. Müller; Stefan Wildi; Thomas Scholz; Pierre-Alain Clavien; Markus Weber

159,345 (SD US


Surgical Endoscopy and Other Interventional Techniques | 2008

High secondary failure rate of rebanding after failed gastric banding

Markus K. Müller; N. Attigah; S. Wildi; Dieter Hahnloser; R. Hauser; Pierre-Alain Clavien; M. Weber

151,191) for grade IV complications. This increase in costs, up to 5 times the cost of a similar operation without complications, was observed for all types of investigated procedures, although the magnitude of the increase varied, with the highest costs in patients undergoing pancreas surgery. Conclusion:This study demonstrates the dramatic impact of postoperative complications on full in-hospital costs per case and that complications are the strongest indicator of costs. Furthermore, the study highlights a relevant savings capacity for major surgical procedures, and supports all efforts to lower negative events in the postoperative course.


British Journal of Surgery | 2008

Long-term follow-up of proximal versus distal laparoscopic gastric bypass for morbid obesity.

Markus K. Müller; S. Räder; Stefan Wildi; R. Hauser; Pierre-Alain Clavien; Markus Weber

BACKGROUND Malnutrition in gastrointestinal (GI) surgery is associated with increased morbidity. Therefore, careful screening remains crucial to identify patients at risk for malnutrition and consequently postoperative complications. The aim of this study was to evaluate the ability of 3 established score systems to identify patients at risk of developing postoperative complications in GI surgery and to assess the correlation among the score systems. METHODS We evaluated prospectively 200 patients admitted for elective GI surgery using (1) nutrition risk index, (2) nutrition risk score, and (3) bioelectrical impedance analysis. Complications were assessed using a standardized complication classification. The findings of the score systems were correlated with the incidence and severity of complications. Parametric and nonparametric correlation analysis was performed among the different score systems. RESULTS All 3 score systems correlated significantly with the incidence and severity of postoperative complications and the duration of hospital stay. Using multiple regression analysis, only nutrition risk score and malignancy remained prognostic factors for the development of complications with odds ratios of 4.2 (P = .024) and 5.6 (P < .001), respectively. The correlation between nutrition risk score and nutrition risk index was only moderate (Pearson coefficient = 0.54). Bioelectrical impedance analysis displayed only weak to trivial correlation to the nutrition risk index (0.32) and nutrition risk score (0.19), respectively. CONCLUSION The nutrition risk score, nutrition risk index, and bioimpedance analysis correlate with the incidence and severity of perioperative complications in GI surgery. The nutrition risk score was the best score in predicting patients who will develop complications in this study population. The correlation between the individual scores was only moderate, and therefore, they do not necessarily identify the same patients.


Blood Coagulation & Fibrinolysis | 2009

Kinetics of D-dimer after general surgery

Daniel Dindo; Stefan Breitenstein; Dieter Hahnloser; Burkhardt Seifert; Sidika Yakarisik; Lars M. Asmis; Markus K. Müller; Pierre-Alain Clavien

Background. This study evaluated the prognostic impact of pretransplant donor-specific anti-human leukocyte antigen antibodies (DSA) detected by single-antigen beads and compared the three generations of crossmatch (XM) tests in kidney transplantation. Methods. Thirty-seven T-cell complement-dependent cytotoxicity crossmatch (CXM) negative living donor kidney recipients with a retrospectively positive antihuman leukocyte antigen antibody screening assay were included. A single-antigen bead test, a flow cytometry XM, and a Luminex XM (LXM) were retrospectively performed, and the results were correlated with the occurrence of antibody-mediated rejections (AMRs) and graft function. Results. We found that (1) pretransplant DSA against class I (DSA-I), but not against class II, are predictive for AMR, resulting in a sensitivity of 75% and a specificity of 90% at a level of 900 mean fluorescence intensity (MFI); (2) with increasing strength of DSA-I, the sensitivity for AMR is decreasing to 50% and the specificity is increasing to 100% at 5200 MFI; (3) the LXM for class I, but not for class II, provides a higher accuracy than the flow cytometry XM and the B-cell CXM. The specificity of all XMs is increased greatly in combination with DSA-I values more than or equal to 900 MFI. Conclusions. In sensitized recipients, the best prediction of AMR and consecutively reduced graft function is delivered by DSA-I alone at high strength or by DSA-I at low strength in combination with the LXM or CXM.

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