Current opinion in general surgery最新文献

Rates of adipose tissue lipolysis are increased in critically ill patients, thus increasing the systemic supply of free fatty acids. This increase in the availability of free fatty acids is probably mediated by various factors including increases in counterregulatory hormones and tumor necrosis factor alpha. The cytokines tumor necrosis factor and interleukin-1 also promote de novo lipogenesis in the liver and may be responsible for impaired triglyceride removal in peripheral tissues; these effects together contribute to the hypertriglyceridemia often seen in septic states. This hypertriglyceridemia may have a teleologic basis, because triglyceride-rich lipoproteins have been shown to bind and inactivate endotoxin. When present in excess, free fatty acids may be responsible for tissue injury in the cold-stored liver allograft, in ischemic-reperfusion cardiac injury, and in ischemic brain injury. Hypoketonemia commonly occurs in septic states and may be due to the combination of a defect in hepatic ketogenesis and accelerated ketone body uptake by peripheral tissues. Both tumor necrosis factor and interleukin-1 have a hypoketonemic effect in animals. Whether ketone bodies have significant protein-sparing properties remains controversial.

That the gastrointestinal tract performs important immunologic, metabolic, and barrier functions, in addition to nutrient digestion and absorption, has recently become clear, as have the potential deleterious consequences of loss of mucosal barrier function. Because of the potentially important relationship between nutrition and gut barrier function, this area has received increasing clinical and experimental attention over the past several years. Consequently, this review focuses on how nutrition can modulate the integrity of the gut mucosal barrier. Special attention will be given to the biology of normal intestinal barrier function, as well as to studies investigating the role of nutritionally related variables on the gut mucosal barrier.

Several new developments promise to improve the lot of the morbidly obese. Perhaps the most important of these is the gradual recognition that morbid obesity is a serious illness that is not the result of immorality or gluttony but is, in most cases, a disabling genetically determined handicap. The second advance was the agreement at the National Institutes of Health Consensus Conference, March 25-27, 1991 that medical therapies generally fail to control severe obesity and that surgery should be considered for those individuals who have a body mass index over 40 and, if the comorbidities of obesity, such as diabetes or sleep apnea, are present, to consider surgical intervention when the body mass index is greater than 35. The third development has been the improvement of bariatric surgery, ie, the surgery for morbid obesity, with better operations, better quality controls, and rigorous follow-up. This article reviews the newer concepts of morbid obesity as a disease, delineates the indications for surgery, describes the currently recommended operations, and presents the risks and benefits of these procedures.

During the past year, several important advances have occurred in the diagnosis and treatment of orthopedic trauma. The increased use of magnetic resonance imaging in the diagnosis of acute cervical spine injuries has enhanced the ability to treat these patients. The development of better fixation systems for the lumbar spine, particularly pedicle screw systems, has increased our ability to stabilize and decompress fractures and fracture-dislocations in this region. New techniques for pelvic stabilization have proved useful in the treatment of these complex injuries. In extremity trauma, the association of compartment syndrome with intramedullary nailing has gained more attention and more aggressive treatment is advocated for fractures secondary to penetrating trauma.

The diagnosis of primary hyperparathyroidism (HPT) relies principally on repeated measurements of total serum calcium and determination of intact parathyroid hormone. A careful patient history and routine blood chemistry will generally verify symptoms in the common patient with HPT, who should be a candidate for surgery. The operative treatment in primary HPT is efficient, with reported high success rate, minimal complications and frequent alleviation of symptoms. Nonoperative medical surveillance should preferentially be considered in elderly patients with borderline increases in serum calcium of around 2.7 mmol/L or less, who in fact constitute a major proportion of hypercalcemic individuals detected at population screening. The patients in whom an operation is deferred should lack any symptoms or complications associated with primary HPT known to benefit from surgery, and this includes the commonly encountered neurobehavioral disability. Surveillance may also occasionally be chosen for really old individuals, when expected improvement fails to justify operative risks. In keeping with the generally liberal indications for parathyroid surgery, surveillance may be time limited if the patients develop disability or display a rise in serum calcium during follow-up.

Hepatic malignancy accounts for a large number of cancer-related deaths worldwide. Radiologic evaluation of the liver is critically important in the selection of patients for surgical treatment and newer modalities including computed tomographic arterial portography and intraoperative sonography show promise in the detection of small lesions. Advances in our understanding of the segmental anatomy of the liver, studies of intraoperative hepatic ischemia, and improved care of patients following major hepatic resections have extended the limits of surgical treatment of liver lesions, especially in cirrhotic patients with limited functional reserve. Along with hepatitis B, new data suggest that hepatitis C is also important as an agent causing hepatocellular carcinoma. In addition, the tumor suppressor gene p53 is frequently mutated in aflatoxin-induced hepatoma. In endemic regions, mass screening for early hepatocellular carcinoma appears to increase the surgical cure rate. Resectional surgery remains the best treatment for primary liver cancer and, in selected cases, liver transplantation is worthwhile. Liver resection for some patients with metastases of colorectal origin is now considered standard therapy and studies of regional chemotherapy for liver cancer are beginning to show promise. It remains to be seen whether adjuvant chemotherapy after liver resection will increase cure rates.

Breast carcinoma remains the most common malignancy and the second leading cause of cancer deaths among adult women in the United States. The benefits of early detection by screening mammography continue to be demonstrated. Fine-needle aspiration biopsy has become established as a highly accurate and cost-effective diagnostic tool that may supplant open surgical biopsy of even nonpalpable breast lesions. The safety and efficacy of breast conservation treatment for early invasive carcinoma continue to be affirmed. Analysis of several issues in management indicate no proven benefit for any different or less aggressive locoregional treatment of early "minimal" or "microinvasive" disease than that applied to later more established forms of invasive breast carcinoma. These frontiers in our understanding of the biology, diagnosis, and treatment of breast carcinoma can best be advanced through scientific investigation of this disease.