Nutrition in acute pancreatitis: a critical review

Severe acute pancreatitis poses unique nutritional challenges. The optimal nutritional support in patients with severe acute pancreatitis has been a subject of debate for decades. This review provides a critical review of the available literature.

According to current literature, enteral nutrition is superior to parenteral nutrition, although several limitations should be taken into account. The optimal route of enteral nutrition remains unclear, but normal or nasogastric tube feeding seems safe when tolerated. In patients with predicted severe acute pancreatitis an on-demand feeding strategy is advised and when patients do not tolerate an oral diet after 72 hours, enteral nutrition can be started. The use of supplements, both parenteral as enteral, are not recommended. Optimal nutritional support in severe cases often requires a tailor-made approach with day-to-day evaluation of its effectiveness.     

The cholesteryl ester transfer protein I405V polymorphism is associated with increased high-density lipoprotein levels and decreased risk of myocardial infarction: the Rotterdam Study.

BACKGROUND AND DESIGN: The effect of the cholesteryl ester transfer protein (CETP) I405V polymorphism on lipid levels, atherosclerosis and myocardial infarction (MI) was examined in 6421 participants from the Rotterdam Study. METHODS: Quantitative outcomes were studied with linear models; Cox models were used to assess MI risk. RESULTS: High-density lipoprotein cholesterol (HDL) increased by 0.06 [95% confidence interval (CI): 0.03, 0.09] mmol/l in VV carriers. The V allele was further associated with decreased MI risk in men [hazard ratio (95% confidence interval)=0.57 (0.45, 0.73), VV versus II] (Ptrend=0.02). CONCLUSION: This study provides additional evidence for the association of CETP with HDL levels and suggests that CETP is an atherogenic protein increasing the risk of MI.     

Inflammatory mediators and cell adhesion molecules as indicators of severity of atherosclerosis: the Rotterdam Study

Inflammatory mediators and soluble cell adhesion molecules predict cardiovascular events. It is not clear whether they reflect the severity of underlying atherosclerotic disease. Within the Rotterdam Study, we investigated the associations of C-reactive protein (CRP), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 with noninvasive measures of atherosclerosis. Levels of CRP were assessed in a random sample of 1317 participants, and levels of IL-6 and soluble cell adhesion molecules were assessed in a subsample of 714 participants. In multivariate analyses, logarithmically transformed CRP (regression coefficient [beta]=-0.023, 95% CI -0.033 to -0.012) and IL-6 (beta=-0.025, 95% CI -0.049 to -0.001) were inversely associated with the ankle-arm index. Only CRP was associated with carotid intima-media thickness (beta=0.018, 95% CI 0.010 to 0.027). Compared with the lowest tertile, the odds ratio for moderate to severe carotid plaques associated with levels of CRP in the highest tertile was 2.0 (95% CI 1.3 to 3.0). Soluble intercellular adhesion molecule-1 levels were strongly associated with carotid plaques (odds ratio 2.5, 95% CI 1.5 to 4.4 [highest versus lowest tertile]). Soluble vascular cell adhesion molecule-1 was not significantly associated with any of the measures of atherosclerosis. This study indicates that CRP is associated with the severity of atherosclerosis measured at various sites. Associations of the other markers with atherosclerosis were less consistent.     

The effect of hormone replacement therapy on serum homocysteine levels in perimenopausal women: a randomized controlled trial

Serum homocysteine levels may be lowered by hormone replacement therapy, but randomized controlled trial data are scarce. We performed a single center randomized placebo-controlled trial to assess the 6 months effect of hormone replacement therapy compared with placebo on fasting serum homocysteine levels in 121 perimenopausal women free of cardiovascular disease, and recruited from the general population. The trial was double-blind with respect to a sequential combined regimen of oral 17 beta-estradiol and desogestrel (17 beta E(2)-D) and the placebo group and open with respect to a combination of conjugated equine estrogens and norgestrel (CEE-N). At baseline and after 6 months, fasting serum homocysteine levels were measured. Differences in 6 months serum homocysteine levels from baseline between treatment and placebo groups were calculated, and expressed as a percentage of the 6 months placebo level. After 6 months, the difference in serum homocysteine levels between women receiving 17 beta E(2)-D and placebo was -6.3% (95% CI, -12.4%; 0.0%, P=0.06). The difference between women receiving CEE-N and placebo was -10.1% (95% CI, -16.7%; -2.9%, P<0.01). The difference between the combined group of both types of hormone replacement therapy users and placebo was -7.8% (95% CI, -13.2%; -2.0%, P=0.01). No significant difference was observed between the two active regimens. Our results indicate that hormone replacement therapy decreases homocysteine levels in perimenopausal women.     

Villous tumors of the duodenum. Presentation of five cases.

Five cases of villous tumors of the duodenum are reported. These tumors have a predilection for the periampullary region and tend to present with jaundice or obstruction of the duodenal lumen. In four of these patients, malignant transformation was seen. Endoscopy and biopsy play a major r?le in attempting to obtain an accurate preoperative diagnosis. Unfortunately, the diagnosis of malignant degeneration is frequently missed, even when multiple biopsies are taken. For this reason villous tumors should always be resected, and the strategy of treatment must depend on pre-, intra- and postoperative histological evaluation, location in the duodenum and intra-operative findings.     

Ultra-protective tidal volume: how low should we go?

Applying tidal volumes of less than 6 mL/kg might improve lung protection in patients with acute respiratory distress syndrome. In a recent article, Retamal and colleagues showed that such a reduction is feasible with conventional mechanical ventilation and leads to less tidal recruitment and overdistension without causing carbon dioxide retention or auto-positive end-expiratory pressure. However, whether the compensatory increase in the respiratory rate blunts the lung protection remains unestablished.Further reducing tidal volumes beyond the standard 6 mL/kg is an appealing goal in patients with acute respiratory distress syndrome (ARDS) [1]. Such reduction could decrease the tidal stretch imposed on the lung, potentially attenuating further the ventilator-induced lung injury [2]. In fact, tidal volumes of less than 6.5 mL/kg and as low as 4 mL/kg were recently associated with increased survival in patients with ARDS [3]. One of the main obstacles to such a strategy is the potential for carbon dioxide (CO₂) retention and severe acidosis. To avoid this, specialized techniques, such as high-frequency oscillatory ventilation and extracorporeal CO₂ removal, have been previously tested with mixed results [4-6].In the previous issue of Critical Care, Retamal and colleagues proposed that lower tidal volumes could be used with conventional positive-pressure ventilation without leading to CO₂ retention [1]. A reduction in tidal volume from 6 to 4 mL/kg was feasible with a decrease in the instrumental dead space and an increase in the respiratory rate. In patients with ARDS, the dead space is a marker of disease severity [7]. Consequently, very low tidal volumes can be difficult to use in practice, especially in very sick patients, because the necessary increase in respiratory rate might cause significant auto-positive end-expiratory pressure (auto-PEEP). Luckily, patients with severe ARDS also tend to have low lung compliance [8], making their lungs inflate and deflate fast. Therefore, this restrictive ventilatory pattern allows the safe use of high respiratory rates without leading to significant auto-PEEP.Retamal and colleagues [1] should be congratulated for their careful design of the ventilator protocol in the 4 mL/kg phase, which allowed an effective CO₂ elimination. The bottom line is that if one decides to use very low tidal volumes with high respiratory rates, attention to the details is invaluable. First, the removal of any dispensable dead space, including substituting an external heated humidifier by the heat-moisture exchanger, is imperative. Second, the use of volume-controlled ventilation helps to keep short inspiratory times. Peak airway pressures may increase, but the preserved expiratory time guarantees low auto-PEEP and, consequently, low plateau pressures. For safety, plateau pressures and auto-PEEP should be measured periodically. Third, in selected cases with high recruitability, the alveolar dead space can be minimized through recruitment maneuvers and higher PEEP values. Finally, the use of a short end-inspiratory pause is encouraged to improve the CO₂ elimination [9]. These measures will improve the safety and optimize the CO₂ elimination of a strategy with very low tidal volumes, even with higher-than-normal respiratory rates.However, even successfully avoiding CO₂ retention, this strategy has yet to be proven effective in terms of further lung protection. We believe that two aspects should be taken into consideration. The first is whether the strategy attenuated the mechanisms of lung injury. The authors performed computed tomography scans in all patients at tidal volumes of both 4 and 6 mL/kg and showed that the amount of cyclic recruitment-derecruitment and hyperinflation decreased after reducing the tidal volume. Although the absolute reduction was small (less than 1% of the lung weight), this finding is suggestive of decreased injury per breath. The second aspect is that an increased respiratory rate can be injurious per se [10]. It would be important to know whether the compensatory increase of the respiratory rate blunted the protective effect per breath of the tidal volume reduction.This tradeoff was emphasized recently in a model of the energy delivered by the ventilator as a surrogate for the potential lung damage [11]. Decreases in tidal volume require disproportionate increases in respiratory rate to maintain alveolar ventilation, and so more energy can be delivered to the lungs even at reduced stress and strain per breath. Though purely theoretical, this hypothesis helps reconcile our expectation of a further protective effect of very low tidal volumes with the recent findings of harmful or null effect of oscillatory high-frequency ventilation [5,6]. In these trials, it is possible that the reduction in lung injury per breath was offset by the very high respiratory rates applied.Finally, Retamal and colleagues [1] followed their patients for 5 to 30 minutes only. Since lower tidal volumes tend to promote atelectasis, especially under insufficient PEEP [12], a longer observation time perhaps would have shown an increase in atelectasis and driving pressures, opposing the benefits initially achieved.In conclusion, we are convinced that a strategy with very low tidal volumes (4 mL/kg) is feasible with conventional positive-pressure ventilation. This strategy could be used in patients with high plateau pressures or high driving pressures with standard 6 mL/kg tidal volumes, but we need more data in terms of lung protection before we can recommend this strategy to every patient with ARDS.     

Blood usage in lung transplantation

BACKGROUND: Few published data are available regarding perioperative blood usage in lung transplantation. STUDY DESIGN AND METHODS: The medical records of all patients undergoing lung transplantation at a university medical center in 1994 and 1995 were reviewed. RESULTS: Ninety patients underwent lung transplantation during this period. Six patients were excluded: two received a living related-donor lung, three underwent retransplantation and one underwent concomitant repair of a tetralogy of Fallot. Of the 84 evaluable patients, 59 underwent single lung transplantation and 25 double lung transplantation. Double-lung recipients used more red cells (6.4 vs. 1.7 units, p = 0.0002) and were more likely to receive red cells, platelets, plasma, or any component (92 vs. 32%, p< or =0.0001) than were single-lung recipients. Double- lung recipients were more likely to require cardiopulmonary bypass (40 vs. 12%, p = 0.003), and cardiopulmonary bypass was associated with greater transfusion requirements (p< or =0.0001). However, among patients requiring cardiopulmonary bypass, blood use did not differ between those undergoing double lung transplantation and those undergoing single lung transplantation. In the subset of patients not requiring cardiopulmonary bypass, double-lung recipients received more red cells (4.5 vs. 0.7 units, p< or =0.0001) and more plasma (2.0 vs. 0.2 units, p = 0.006). CONCLUSION: Double-lung recipients require more perioperative transfusions than single-lung recipients. The greater transfusion requirement is due to the more frequent need for cardiopulmonary bypass as well as the greater complexity of the procedure. These data are useful for developing surgical blood ordering guidelines for lung transplantation.     

Variables of the insulin resistance syndrome are associated with reduced arterial distensibility in healthy non-diabetic middle-aged women

Aims/hypothesis. The insulin resistance syndrome is related to arterial stiffness in diabetic subjects. Whether the insulin resistance syndrome is also related to arterial stiffness in non-diabetic subjects is less clear. We studied the association between variables of the insulin resistance syndrome in relation to arterial distensibility in healthy middle-aged non-diabetic women. Methods. This study was done in 180 non-diabetic women, aged 43–55, selected from the general population. Arterial distensibility was assessed in the carotid artery. The associations were evaluated using linear regression analyses. Results. Strong associations were found between arterial distensibility and the variables of the insulin resistance syndrome: body mass index, waist-to-hip ratio, high-density-lipoprotein-cholesterol, triglycerides, glucose, insulin, apolipoprotein A1, plasminogen activator inhibitor-1-antigen and tissue-type plasminogen activator-antigen. After additional adjustment for mean arterial pressure, common carotid arterial distensibility remained associated with body mass index: β-coefficient (95 % confidence interval) per kg/m²: –0.24 (–0.42; –0.06); waist-to-hip ratio: –26.62 (–40.59; –12.65) per m/m; triglycerides: –1.42(–2.77; –0.08) per mmol/l; plasminogen activator inhibitor–1-antigen: –0.01 (–0.02; –0.00) per ng/ml and borderline significant associated with high-density-lipoprotein-cholesterol: 1.93 (–0.01; 3.87; p = 0.07) per mmol/l. Clustering of variables of the insulin resistance syndrome was strongly related to decreased arterial distensibility which remained after adjustment for mean arterial pressure. No association was found between arterial distensibility and variables that are not part of the insulin resistance syndrome: total cholesterol, LDL-cholesterol and apolipoprotein B. Conclusion/interpretation. The results of this study show that variables of the insulin resistance syndrome are associated with decreased arterial distensibility of the common carotid artery in healthy non-diabetic subjects. [Diabetologia (2000) 43: 665–672] Received: 17 November 1999 and in revised form: 24 January 2000     

Neonatal treatment with 192 IgG-saporin produces long-term forebrain cholinergic deficits and reduces dendritic branching and spine density of neocortical pyramidal neurons

The role of basal forebrain-derived cholinergic afferents in the development of neocortex was studied in postnatal rats. Newborn rat pups received intraventricular injections of 192 IgG-saporin. Following survival periods ranging from 2 days to 6 months, the brains were processed to document the cholinergic lesion and to examine morphological consequences. Immunocytochemistry for choline acetyltransferase (ChAT) and in situ hybridization for ChAT mRNA demonstrate a loss of approximately 75% of the cholinergic neurons in the medial septum and nucleus of the diagonal band of Broca in the basal forebrain. In situ hybridization for glutamic acid decarboxylase mRNA reveals no loss of basal forebrain GABAergic neurons. Acetylcholinesterase histochemistry demonstrates a marked reduction of the cholinergic axons in neocortex. Cholinergic axons are reduced throughout the cortical layers; this reduction is more marked in medial than in lateral cortical areas. The thickness of neocortex is reduced by approximately 10%. Retrograde labeling of layer V cortico-collicular pyramidal cells reveals a reduction in cell body size and also a reduction in numbers of branches of apical dendrites. Spine densities on apical dendrites are reduced by approximately 20-25% in 192 IgG- saporin-treated cases; no change was detected in number of spines on basal dendrites. These results indicate a developmental or maintenance role for cholinergic afferents to cerebral cortical neurons.