Cation Exchange Resins and colonic perforation. What surgeons need to know.

INTRODUCTION: Since 1961 the use of Cation Exchange Resins has been the mainstream treatment for chronic hyperkalemia. For the past 25 years different kind of complications derived from its clinical use have been recognized, being the colonic necrosis the most feared and lethal of all. PRESENTATION OF CASE: We report a case of a 72-year-old patient with chronic kidney disease, treated with calcium polystyrene sulfonate for hyperkalemia treatment who presented in the emergency department with constipation treated with hypertonic cathartics. With clinical deterioration 48h later progressed with colonic necrosis requiring urgent laparotomy, sigmoidectomy and open abdomen management with subsequent rectal stump perforation and dead. The histopathology finding: calcium polystyrene sulfonate embedded in the mucosa, consistent with the cause of perforation. DISCUSSION: Lillemoe reported the first case series of five uremic patients with colonic perforation associated with the use of SPS in sorbitol in 1987 and in 2009 the FDA removed from the market the SPS containing 70% of sorbitol. The pathophysiologic change of CER goes from mucosal edema, ulcers, pseudomembranes, and the most severe case transmural necrosis. Up to present day, some authors have questioned the use of CER in the setting of lowering serum potassium. Despite its worldwide use in hyperkalemia settings, multiple studies have not demonstrated a significant potassium excretion by CER. CONCLUSION: Despite the low incidence of colonic complication and lethal colonic necrosis associated with the CER clinical use, the general surgeon needs a high index of suspicion when dealing with patients treated with CER and abdominal pain.

Total Mesorectal Excision, an erroneous anatomical term for the gold standard in rectal cancer treatment.

In 1986 Professor R J Heald published in The Lancet his new technique which he called Total Mesorectal Excision; today this is the gold standard for the surgical management of rectal cancer. In Total Mesorectal Excision (TME), the mesorectum is the term used to describe all the peri-rectal connective tissue including the posterior sheath of the endopelvic fascia containing the peri-rectal neurovascular structures. However, the mesenterium is a defined structure composed of a double layer of peritoneum which does not include the endopelvic fascia and the lateral rectal stalks, so these should not be included in the term 'mesorectum'. In our globalized medical culture it is important to use anatomic terms approved by the International Federation of Associations of Anatomists, as contained in the Terminologia Anatomica produced by the Federative International Programme for Anatomical Terminology (FIPAT). The term mesorectum is not listed in the Terminologia Anatomica.

Improved chemical control of Chagas disease vectors in the dry Chaco region.

The effectiveness of two doses of suspension concentrate (SC) pyrethroid insecticides in suppressing peridomestic populations of Triatoma infestans (Klug) was evaluated in 28 rural communities located in Santiago del Estero province, northwestern Argentina, including 388 houses and 1,516 identified sites. Four treatments were randomly assigned to peridomiciles within each community: 5% SC beta-cypermethrin at standard (S, 50 mg active ingredient [AI]/m2) and double dose (2S), and 2.5% SC deltamethrin at standard (D, 25 mg [AI]/m2) and double dose (2D). Simultaneously, we assessed the effects of both pyrethroids applied at standard doses against domestic infestations. Bug infestation at the site level was assessed by timed manual collections with a dislodging agent at baseline, 13 and 21 mo postspraying (MPS). In domiciles, D and S nearly suppressed all T. infestans infestations up to 21 MPS. In peridomestic sites infested before interventions, multiple logistic regression analysis showed that site-level reinfestation at 13 MPS was significantly lower for treatment 2D (1%) than for other treatments, whereas 2S (6%), D (5%), and S (14%) did not differ significantly between them. The risk of reinfestation after spraying was significantly greater in goat or pig corrals than in other peridomestic ecotopes (in which treatments did not differ significantly), and in sites infested before interventions than in uninfested sites. The application of SC deltamethrin at double dose in goat or pig corrals may suppress T. infestans foci and achieve more sustained effects in the dry Chaco.

Comparative trial of effectiveness of pyrethroid insecticides against peridomestic populations of Triatoma infestans in northwestern Argentina.

The effects of different pyrethroid insecticides, formulations, and doses on peridomestic populations of Triatoma infestans (Klug) were evaluated in 128 houses with 148 identified infested peridomestic sites in northwestern Argentina between October 2003 and March 2005. Four treatments were randomly assigned within each community: two doses of 5% suspension concentrate beta-cypermethrin in water applied with manual compression sprayers, the standard dose (S) at 50 mg and a double dose (2S) at 100 mg active ingredient (AI)/m2; and two emulsifiable concentrates diluted in diesel fuel and applied with power sprayers, 25% cypermethrin (100 mg [AI] /m2) (CF) and 10% permethrin (170 mg [AI]/m2) (DF). Infestation was assessed by timed manual collections with a dislodging agent at baseline, 5, 12, and 17 mo postspraying, and the sites found to be reinfested at 5 mo postspraying were selectively resprayed. Only 2S eliminated T. infestans from all peridomestic sites up to 12 mo postspraying, and it was significantly more effective than all other treatments. At 5 mo postspraying, more sites treated with CF or DF rather than S had bug colonies that probably represented residual foci, which they also failed in eliminating after a second spray. At 17 mo postspraying, the prevalence of reinfested peridomestic sites was 5% for 2S, 29% for S, 43% for CF, and 54% for DF. The application of suspension concentrate pyrethroids in dose twice as large as that currently in use in the attack phase produces a greater initial impact and may eliminate peridomestic populations of T. infestans.