Management of postoperative ileus: focus on alvimopan

Postoperative ileus (POI) is a transient loss of coordinated peristalsis precipitated by surgery and exacerbated by opioid pain medication. Ileus causes a variety of symptoms including bloating, pain, nausea, and vomiting, but particularly delays tolerance of oral diet and liquids. Thus POI is a primary determinant of hospital stay after surgery. ‘Fast-track’ recovery protocols, opioid sparing analgesia, and laparoscopic surgery reduce but do not eliminate postoperative ileus. Alvimopan is a mu opioid receptor antagonist that blocks the effects of opioids on the intestine, while not interfering with their centrally mediated analgesic effect. Several large randomized clinical trials have demonstrated that alvimopan accelerates the return of gastrointestinal function after surgery and subsequent hospital discharge by approximately 20 hours after elective open segmental colectomy. However, it has not been tested in patients undergoing laparoscopic surgery and is less effective in patients receiving nonsteroidal anti-inflammatory agents in a narcotic sparing postoperative pain control regimen. Safety concerns seen with chronic low dose administration of alvimopan for opioid bowel dysfunction have not been noted with its acute use for POI

Single Incision Laparoscopic Colectomy: Technical Aspects, Feasibility, and Expected Benefits

Background. This paper studied technical aspects and feasibility of single incision laparoscopic colectomy (SILC). Methods. Bibliographic search was carried out up to October 2009 including original articles, case reports, and technical notes. Assessed criteria were techniques, operative time, scar length, conversion, complications, and hospitalization duration. Results. The review analyzed seventeen SILCs by seven surgical teams. A single port system was used by four teams. No team used the same laparoscope. Two teams used two laparoscopes. All teams used curved instruments. SILC time was 116 ± 34 minutes. Final scar was longer than port incision (31 ± 7 versus 24 ± 8 mm; P = .036). No conversion was reported. The only complication was a bacteremia. Hospitalization was 5 ± 2 days. Conclusion. SILC is feasible. A single incision around the umbilical scar represents cosmetic progress. Comparative studies are needed to assess potential abdominal wall and recovery benefits to justify the increased cost of SILC

Approximate Bayesian Computation for Studying Selective Sweep Signatures in Local Coalescence Trees

Understanding the process of rapid molecular adaptation is important for many key challenges humanity faces today, such as the evolution of pesticide and drug resistance. Our standard population genetic model for describing rapid molecular adaption is the selective sweep, in which a previously rare or absent allele is quickly driven to fixation by positive selection. Selective sweeps can be distinguished into hard sweeps, where a single adaptive mutation arises in the population and then goes to fixation, and soft sweeps, where several adaptive mutations at the same locus rise in the population simultaneously. These soft sweeps can occur either because the adaptive alleles were already present as standing genetic variation (SGV) at the onset of positive selection, or because they arose independently from recurrent de novo mutation (RDN). In this thesis, I develop an Approximate Bayesian Computation (ABC) approach to study whether we can distinguish these different sweep types and infer their evolutionary parameters from the shape of the local coalescence tree at the sweep locus. I demonstrate that my method can reliably infer the selection coefficient and softness of a sweep under various parameter settings. I further show how my method can be used with Bayes factors for differentiating between soft sweeps from SGV and those from RDN, as well as from neutral selection. These findings demonstrate that the local coalescence tree at a sweep locus contains valuable information on the parameters of the sweep and motivates further studies that aim to infer such trees from real population genomic data through reconstruction of ancestral recombination graphs