The effect of occlusive dressings on the energy metabolism of severely burned children.

Metabolic studies were performed on 23 burned children. They were studied sequentially until their burn wounds were healed. A metabolic study lasted 20 minutes, during which continuous measurements were made of O2 consumption and CO2 production rates, rectal temperature, average surface temperatures (dressings, skin and wound), body heat content, and rate of body weight loss using a bed scale. These measurements allowed solution of the heat balance equation for each study period. After 24 hours in a constant temperature room kept at 28 C and 40% relative humidity, metabolic studies were initiated when blood was drawn for catecholamine assay, followed by a metabolic analysis, after which dressings were removed and fresh silvadene applied to the wounds. No dressings were applied. Metabolic analyses were repeated after two and four hours of exposure, after which blood for catecholamine analysis was drawn and the study terminated. Without dressings in a thermally neutral environment, burn patients demonstrated an increased rate of heat loss of 27 watts/square meter body surface area (W/M2), compared with the predicted normal. The major portion of this increment is by evaporation, which increased 300%. The rate of heat production equals heat loss, and is increased 50% above the predicted normal. Occlusive dressings result in a 15 W/M2 decrease in the rate of heat loss, about evenly divided between evaporative and dry routes, with a corresponding 15 W/M2 decrease in the rate of heat production. Plasma catecholamine levels of bandaged burn patients are not significantly different from values for healed burn patients, and do not correlate with the rate of heat production. The increased heat production of burn patients is a response to an increased rate of heat loss, not vice versa. The use of occlusive dressings substantially reduces the energy requirements to manageable levels, even in patients with very large burns.     

The factor age and the recovery of severely burned children

Purpose

It is not known if the recovery of pediatric burn patients is age-dependent. The aim of this study was to investigate the effect of age on the recovery of body composition of severely burned children.

Procedures

Pediatric patients with massive burns, ≥40% of total body surface area, were followed over 2 years. Patients were divided into two age groups: 0–3.9 years old and 4–17.9 years old at the time of burn.Body composition was determined at hospital discharge, 6, 9, 12, 18, and 24 months after burn using dual-X-ray absorptiometry. Data analysis was performed using a two way ANOVA followed by Tukey's correction when appropriate. Significance was accepted at p < 0.05.

Findings

Twenty-four patients were enrolled (age 0–3.9: n = 9; age 4–17.9: n = 15). Percent changes in height and bone mineral content were significantly increased in the younger age group, p < 0.05. In contrast, percent changes in lean body mass were significantly lower in younger patients, p < 0.05. Percent changes in total body fat mass were not affected.

Conclusion

Patterns of recovery in pediatric burn patients are determined by age. This observation should be considered in the development of therapeutic approaches.     

异丙酚靶控输注对健康志愿者脑葡萄糖代谢的影响

目的 应用正电子发射断层扫描(PET)技术,比较健康志愿者在清醒和异丙酚靶控输注(FCI)致意识消失状态下大脑不同解剖结构间葡萄糖代谢的差异。方法 健康男性志愿者5名,分别在清醒和意识消失期作PET扫描。意识消失期以异丙酚效应室浓度(ECC)2.5μg/ml为初始浓度,以±0.2μg/ml浓度梯度调整志愿者意识状态至改良OAA/S1分,并维持此ECC至扫描结束。~(18)FDG10mci推注完毕开始计时,在0～4.5(T_1)、4.5～9.5(T_2)、9.5～29.5(T_3)、29.5～44.5(T_4)、44.5～59.5(T_5)、(59.5～74.5)min(T_6)6个时段进行扫描。数据重建后立体定向选取全脑、额叶、顶叶、颞叶、枕叶、尾状核、豆状核、丘脑、小脑等感兴趣区域(ROI),并将各ROI闪烁点计数转化为标准摄取值(SUV),比较意识消失期各ROI在各时段与清醒期SUV的差异及其降低百分比。结果 T_(1-6)时段随时间延长全脑和各ROI的SUV降低百分比逐渐增加。与全脑比较,枕叶T_6时段SUV降低百分比增加、豆状核T_(3-5)时段SUV降低百分比降低(P<0.05或0.01)。与丘脑比较,尾状核、豆状核T_(2～6)时段SUV降低百分比降低(P<0.05)。T_(3～6)时段意识消失期SUV明显低于清醒期(P<0.01)。两期主要皮质区、皮质下中枢及小脑SUV均随时间延长而增加,相同时段比较均无统计学意义。L_(4～6)时段,清     

Effects of delayed wound excision and grafting in severely burned children

HYPOTHESIS: Advances in burn treatment including early excision of the wound have increased survival in patients treated at specialized burn centers. We hypothesized that the patients with delayed wound excision and grafting would experience deleterious outcomes. METHODS: From 1995 to 1999, 157 children with acute burns covering 40% or more of total body surface area and having more than 10% of full-thickness burns were admitted to our institution within 2 weeks of injury. Among them, 86, 42, and 29 patients underwent first operation on days 0 to 2, days 3 to 6, and days 7 to 14 after burn, respectively. Outcomes observed were mortality, number of operative procedures, length of hospitalization, blood transfused, incidence of wound bacterial and fungal contamination, invasive wound infection, and sepsis. RESULTS: Demographic data for the groups showed no differences in sex or total body surface area burned. Mortality and number of operative procedures and blood transfusions were not different between groups. Hospitalizations were longer in the delayed groups, which was associated with a higher incidence of significant wound contamination (P =.008). Invasive wound infection also increased significantly with delay of excision (P<.001). An increased incidence of sepsis was seen in patients with delayed wound excision and grafting (P =.04). CONCLUSIONS: Delays in excision were associated with longer hospitalization and delayed wound closure, as well as increased rates of invasive wound infection and sepsis. Our data indicate that early excision within 48 hours is optimal for pediatric patients with massive burns.     

Determinations of glucose turnover and oxidation in normal volunteers and septic patients using stable and radio-isotopes: the response to glucose infusion and total parenteral feeding

Rates of glucose turnover and oxidation were isotopically determined in normal volunteers (n = 16) and in severely septic patients (n = 10). Glucose turnover was determined using primed constant infusions of either 6-3H- or 6,6-d-glucose and glucose oxidation with either U-14C-glucose or U-13C-glucose after appropriate priming of the bicarbonate pool. Basal rates of glucose turnover, oxidation, and plasma clearance were significantly higher in the septic patients than in the volunteers. During glucose infusion (4 mg/kg.min) endogenous glucose production was virtually abolished in the volunteers (94 +/- 4% suppression). There was significantly less suppression in the septic patients (39 +/- 7%); (P less than 0.01). In addition, the percentage of available glucose oxidized (i.e. the percentage of glucose uptake oxidized) was significantly less in the septic patients. When the patients were studied during total parenteral nutrition (at a similar rate of glucose infusion) there was no further suppression of endogenous glucose production compared with that seen during 2 h of glucose infusion. However, the percentage of available glucose oxidized increased significantly. From these studies it is concluded that septic patients continue to have ongoing consumption of host tissue despite receiving either glucose infusion or total parenteral nutrition, and septic patients are less able to oxidize glucose than normal volunteers when infused for only 2 h. However, adaptation occurs with the longer infusion time used in total parenteral nutrition (TPN).     

Increased liver weights in severely burned children: comparison of ultrasound and autopsy measurements

Hepatomegaly is a common finding at autopsy in severely burned children surviving less than 6 months. This study validates a reliable ultrasound method which can be used to identify changes in liver size in severely burned children during acute hospitalization. Thirty-eight children, age 0.5-17 years with burns covering over 40% of their total surface area were studied at autopsy. Liver weight was measured at autopsy and compared to predicted liver weight for age and height. Eighteen had liver size measured by ultrasound within 10 days of death while five had ultrasound liver measures after death just prior to autopsy. All burned children who survived 7 days or more (n = 33) had liver weights at autopsy that were greater than predicted for age and height while all 23 livers measured by ultrasound were greater than predicted. Autopsy weights correlated well with weights estimated by ultrasound, R = 0.824. At autopsy, those who survived 7 days or more had enlarged livers ranging from 142 to 406% of their predicted normal age and height. Common histologic findings include large and small-droplet fat deposits, and cholestasis. The degree of these histologic abnormalities correlated with the increase in liver weight, R = 0.652. Ultrasound is a valid, noninvasive method for measuring liver weight changes in severely burned children during acute hospitalization. Ninety-five percent of the severely burned children from this institute had significant hepatomegaly identified at autopsy.     

血液滤过治疗严重烧伤脓毒症伴发的高钠血症

目的探讨血液滤过对严重烧伤脓毒症合并高钠血症病人的疗效.方法应用持续静脉-静脉血液滤过方法治疗8例严重烧伤脓毒症合并高钠血症的病人.观察病情、外周血电解质、血流动力学、氧摄取率变化;检测血滤开始时、血滤结束时血浆内炎性介质(IL-1β、IL-6、IL-8和TNF-α)浓度变化以及滤液中上述炎性介质的含量,计算跨膜清除率.结果病人经血液滤过治疗后,临床症状好转,血流动力学趋于稳定,血钠浓度恢复至生理水平.动脉血氧饱和度、氧分压以及氧摄取率均明显升高,差异有显著意义(P＜0.01).血滤结束时血浆内IL-1β、IL 6、IL-8和TNF-α的浓度较血滤前明显下降,差异有显著意义(P＜0.01).超滤液中也检测到上述4种细胞因子.随血滤时间延长,IL-1β、IL-6跨膜清除率明显下降,差异有显著意义(P＜0.01),IL-8和TNF-α跨膜清除率无明显变化,差异无显著意义(P＞0.05).结论血液滤过能在较短的时间内平稳而有效降低病人外周血钠离子浓度,并能部分清除体内IL-1β、IL-6、IL-8和TNF-α等炎性介质,平衡机体炎性反应,稳定血流动力学、改善病情,对治疗烧伤脓毒症伴发的高钠血症,降低其高病死率有积极作用.     

Influence of glucose kinetics on plasma lactate concentration and energy expenditure in severely burned patients

BACKGROUND: In critically ill patients, elevation in the plasma lactate concentration has traditionally been interpreted as indicating a deficiency in oxygen availability and is often an impetus to increase oxygen delivery clinically. However, another possible basis for increased lactate concentrations may be simply a mass effect from increased pyruvate availability (i.e., accelerated glycolysis). METHODS: In six hypermetabolic burned patients, the rates of glucose production and oxidation were quantified using a tracer infusion of 6,6 d2 glucose combined with indirect calorimetry. Measurements were obtained after a 9-hour fast and after a 3-hour infusion of unlabeled glucose at 30 micromol/kg/min. No patient was overtly septic, hypoxic, or hypovolemic. RESULTS: The infusion of glucose significantly increased the arterial glucose concentration and rate of glucose oxidation, with a corresponding increase in the arterial plasma concentration of lactate and pyruvate. Resting energy expenditure and oxygen consumption were not affected by the infusion of glucose. CONCLUSIONS: These findings show that elevations in plasma lactate in severely injured patients may, in part, be related to increases in glucose flux and not entirely a reflection of any deficit in oxygen availability. Such findings highlight a potential pitfall for interpreting plasma lactate concentrations as an index of tissue oxygen availability in hypermetabolic patients.     

The effects of free fatty acid infusion on glucose metabolism in normal and streptozotocin-treated dogs.

By means of a novel technique for direct intravenous infusion of free fatty acids (FFA) into conscious dogs, it was found that the elevation of FFA levels in normal animals leads to a marked increase in insulin release and to a decrease in plasma glucose concentration. Dogs with streptozotocin-induced diabetes were used for FFA infusion in order to test whether peripheral glucose utilisation would be suppressed by FFA in the absence of the usual insulin response. Diabetic dogs receiving a constant infusion of intravenous glucose were given infusions of oleic acid after control periods of 2-3 hours. Constant intravenous infusion of U-14C-glucose into the diabetic dogs indicated that FFA infusion caused an average transient drop of 36,8% in glucose flux. After 1 1/2 hours of FFA infusion the flux returned to the former rates. Because no change in plasma glucose levels was found during FFA infusion our results can be explained only by a drop in hepatic glucose production concomitant with an equal drop in peripheral glucose utilisation.     

肠饲谷氨酰胺对严重烧伤小型香猪肠道葡萄糖代谢的影响

采用小型香猪３０％ＴＢＳＡ烧伤模型，动态观察了烧伤后肠道补充谷氨酰胺对肠道葡萄糖代谢的影响，结果显示：伤后第１天，不补充谷氨酰胺组肠道葡萄糖的消耗量明显减少，而补充谷氨酰胺组则出现少量的净释放，为０．１１μｍｏｌ·ｍｉｎ－１·ｋｇ－１。伤后第４天，两组均出现净释放，补充谷氨酰胺的动物明显高于不补充谷氨酰胺的动物；伤后７、１０天，两组仍维持葡萄糖的净释放。提示严重烧伤后肠道补充谷氨酰胺能明显减少肠道对葡萄糖的利用，增加肠道葡萄糖的生成能力。     

Effect of epidural blockade on protein, glucose, and lipid metabolism in the fasted state and during dextrose infusion in volunteers

BACKGROUND: To interpret correctly the results from studies performed during surgery and anesthesia it is necessary to dissect the separate effect of the anesthetic technique itself. The purpose of this study was to investigate the metabolic effects of epidural blockade (T7-S1) with bupivacaine 0.25% after 12 h fasting and during administration of 4 mg x kg(-1) x min(-1) dextrose in six healthy volunteers. METHODS: Each volunteer was assigned to randomly undergo a 6-h multiple stable isotope infusion study (3 h fasted, 3 h dextrose infusion) with or without epidural blockade. L-[1-13C]leucine, [6,6-2H2]glucose, and [1,1,2,3,3-2H5]glycerol were infused to measure protein synthesis, breakdown, and amino acid oxidation; glucose production and clearance; and lipolysis. Plasma concentrations of glucose, lactate, glycerol, free fatty acids, insulin, and glucagon were determined. RESULTS: Epidural blockade with bupivacaine had no influence on protein oxidation, breakdown and synthesis, glucose production, glucose clearance and lipolysis in the fasted state. Plasma concentrations of metabolic substrates and hormones also were not affected. Dextrose infusion significantly increased glucose clearance and plasma concentrations of glucose and insulin, while endogenous glucose production and lipolysis decreased to a similar degree in both groups. Protein synthesis, breakdown, and oxidation did not change during dextrose infusion. CONCLUSIONS: Epidural blockade with bupivacaine in the absence of surgery has no effect on fasting protein, glucose, and lipid metabolism. Epidural blockade does not modify the inhibitory influence of dextrose administration on endogenous glucose production and lipolysis.     

The influence of age and gender on resting energy expenditure in severely burned children

INTRODUCTION: Recent evidence suggests that female severely burned children have higher endogenous anabolic hormone levels and a shorter ICU stay compared with males. The purpose of this study was to analyze the influence of age and gender on resting energy expenditure (REE) in severely burned children from acute hospitalization through 12 months postburn. METHODS: A total of 100 pediatric patients with > 40% total body surface area (TBSA) burn were enrolled in a prospective study and followed by indirect calorimetry measurements. The REE was expressed as actual REE kcal/d, percent of predicted REE, and REE/ body mass index (BMI). Statistical analysis was performed by Student t test and one-way ANOVA for repeated measures. Significance was accepted at P < 0.05. RESULTS: The measured REE was significantly higher in males versus females at all time points (P < 0.05). The percent of predicted REE was significantly higher in males versus females during the acute hospitalization, at discharge, 6 and 9 months postburn (P < 0.05). The REE/BMI showed a significant difference between males and females at the acute and discharge time period (P < 0.05). In children 3 to 9.9 years of age, the measured REE and the percent of predicted REE were significantly higher in males versus females during the acute study, at discharge and 6 months postburn (P < 0.05). The measured REE at discharge, 9 and 12 months postburn for children >10 years of age was significantly higher in males compared with females (P < 0.05). CONCLUSION: Data show that female children exert a decreased hypermetabolic response compared with male children, which may improve burn outcomes in females.     

Early escharectomy in children: the indications and limits in the severely burned patient. A preliminary report]

A trial was carried out to assess the benefit of early eschar excision in order to improve the survival rate in severely burnt children. The study included two groups of patients treated using different methods. The mortality rate, amount of blood lost and length of hospital stay were evaluated for each group. Preliminary results seem to confirm the effectiveness of this technique provided that some conditions are met, namely the quantity of necrotic tissue removed and the amount of blood lost during the entire hospital stay.     

肠饲谷氨酰胺对严重烧伤小型香猪肠道葡萄糖代谢的影响

采用小型香猪30%TBSA 烧伤模型,动态观察了烧伤后肠道补充谷氨酰胺对肠道葡萄糖代谢的影响。结果显示:伤后第1天,不补充谷氨酰胺组肠道葡萄糖的消耗量明显减少,而补充谷氨酰胺组则出现少量的净释放。为0.11μmol·min~(-1)·kg~(-1)。伤后第4天,两组均出现净释放,补充谷氨酰胺的动物明显高于不补充谷氨酰胺的动物;伤后7、10天,两组仍维持葡萄糖的净释放。提示严重烧伤后肠道补充谷氨酰胺能明显减少肠道对葡萄糖的利用,增加肠道葡萄糖的生成能力。     

Disorders of bone metabolism in severely handicapped children and young adults

There is a high prevalence of vitamin D deficiency in the severely handicapped pediatric population. Because many of these patients have growth deficiencies, they may not demonstrate wide growth plates commonly seen with vitamin D deficiency. There is also a high prevalence of anticonvulsant use in these patients, and its exact impact is not clear because of the variety of its effects and presentations. Calcium, phosphate, and alkaline phosphatase are not useful as indicators of vitamin D deficiency, and vitamin D metabolites must be measured directly. Patients with low vitamin D levels respond to treatment, including nutritional support and added sunlight exposure. The overall nutritional status of this population may be reflected in their metabolic bone disease and small stature.