Brain glucose and lactate levels during ventilator-induced hypo- and hypercapnia

OBJECTIVE: Levels of glucose and lactate were measured in the brain by means of microdialysis in order to evaluate the effects of ventilator-induced hypocapnia and hypercapnia on brain metabolism in healthy non-brain-traumatized animals. DESIGN AND SETTING: Prospective animal study in a university laboratory. SUBJECTS: Eight adult Landrace/Yorkshire pigs. INTERVENTIONS: The microdialysis probe was inserted in the brain along with a multiparameter sensor and intracranial pressure (ICP) probe. The animals were ventilated in a pressure-controlled mode according to the open lung concept with an inspired oxygen fraction of 0.4/1.0. Starting at normoventilation (PaCO(2) +/-40 mmHg) two steps of both hypercapnia (PCO(2) +/- 70 and 100 mmHg) and hypocapnia (PaCO(2) +/- 20 and 30 mmHg) were performed. Under these conditions, brain glucose and lactate levels as well as brain oxygen (PbrO(2)), brain carbon dioxide (PbrCO(2)), brain pH (brpH), brain temperature and ICP were measured. RESULTS: At hypercapnia (PaCO(2) = 102.7 mmHg) there were no significant changes in brain glucose and lactate but there was a significant increase in PbrCO(2), PbrO(2) and ICP. In contrast, at hypocapnia (PCO(2) = 19.8 mmHg) there was a significant increase in brain lactate and a significant decrease in both brain glucose and PbrCO(2). CONCLUSIONS: Hypocapnia decreases brain glucose and increases brain lactate concentration, indicating anaerobic metabolism, whereas hypercapnia has no influence on levels of brain glucose and brain lactate.     

Continuous on-line glucose measurement by microdialysis in a central vein. A pilot study

Introduction

Tight glucose control in the ICU has been proven difficult with an increased risk for hypoglycaemic episodes. Also the variability of glucose may have an impact on morbidity. An accurate and feasible on-line/continuous measurement is therefore desired. In this study a central vein catheter with a microdialysis membrane in combination with an on-line analyzer for continuous monitoring of circulating glucose and lactate by the central route was tested.

Methods

A total of 10 patients scheduled for major upper abdominal surgery were included in this observational prospective study at a university hospital. The patients received an extra central venous catheter with a microdialysis membrane placed in the right jugular vein. Continuous microdialysis measurement proceeded for 20 hours and on-line values were recorded every minute. Reference arterial plasma glucose and blood lactate samples were collected every hour.

Results

Mean microdialysis-glucose during measurements was 9.8 ± 2.4mmol/l.No statistical difference in the readings was seen using a single calibration compared to eighth hour calibration (P =0.09; t-test). There was a close agreement between the continuous reading and the reference plasma glucose values with an absolute difference of 0.6+0.8mmol, or 6.8+9.3% and measurements showed high correlation to plasma readings (r = 0.92). Thelimit of agreement was 23.0%(1.94 mmol/l) compared to arterial plasma values with a line of equality close to zero.However, in a Clarke-Error Grid 93.3% of the values are in the A-area,and the remaining part in the B-area.Mean microdialysis-lactate was 1.3 ± 1.1mmol/l. The measurements showed high correlation to the blood readings (r = 0.93).

Conclusion

Continuous on-line microdialysis glucose measurement in a central vein is a potential useful technique for continuous glucose monitoring in critically ill patients, but more improvements and testingare needed.     

Inhibition of paracrine angiotensin-converting enzyme in vivo: effects on interstitial glucose and lactate concentrations in human skeletal muscle

Microdialysis was used to selectively assess the effect of the paracrine renin–angiotensin system (RAS) on interstitial glucose and lactate concentration profiles in skeletal muscle of healthy volunteers ( n  = 8) during basal and insulin-stimulated conditions. Paracrine RAS was selectively inhibited by local retrodialysis with enalaprilate. Under basal conditions, local administration of enalaprilate (2 μg mL⁻¹) increased interstitial dialysate glucose concentration from 0.71 ± 0.14 mmol L⁻¹ to 0.84 ± 0.14 mmol L⁻¹ and decreased the serum interstitial gradient (SIG_glu) compared with baseline ( P  < 0.02). Under clamp conditions, enalaprilate, even at the lowest concentration (0.02 μg mL⁻¹), increased interstitial dialysate glucose concentration from 0.77 ± 0.11 mmol L⁻¹ to 1.02 ± 0.09 mmol L⁻¹ and decreased SIG_glu compared with baseline ( P  < 0.01). Interstitial lactate concentrations slightly increased during basal as well as during clamp conditions ( P  < 0.05 vs. baseline). Selective inhibition of paracrine muscle angiotensin-converting enzyme (ACE) increases interstitial glucose and lactate concentrations and decreases SIG_glu in muscle by facilitating transcapillary glucose transport. This effect is more pronounced during hyperinsulinaemia and may be of clinical relevance in diabetic patients treated with therapeutic doses of enalapril.     

Key metabolite kinetics in human skeletal muscle during ischaemia and reperfusion: measurement by microdialysis

Abstract. The tissue kinetics of key metabolites of ischaemic and postischaemic tissue damage were studied in the intercellular space of human skeletal muscle by microdialysis. In vivo microdialysis calibration experiments ( n = 5) yielded the basal intercellular concentration of glucose in human skeletal muscle (3.6±0.6mM; mean±SD). The corresponding mean plasma glucose concentration was 4.3 ± 0.2 mM which was significantly higher. The time vs. concentration profiles of intercellular glucose ( n = 7), lactate ( n = 5), TxB₂ ( n = 6) and urea ( n = 8) were characterized during a 20 min period of leg constriction. TxB₂ increased exclusively during reperfusion in comparison to baseline ( n = 6). Administration of 500 mg acetylsalicylic acid, 5–10min after onset of ischaemia blunted TxB₂-response to reperfusion ( n = 4). It is concluded that intercellular muscle glucose concentration is less than that in plasma. Glucose uptake in skeletal muscle is rapid even under ischaemic conditions. Synthesis and release of TxB₂ is not evident during ischaemia. TxB₂ mediated reperfusion injury might be reduced by acetylsalicylic acid, even if administered after onset of ischaemia.     

Application of cutaneous microdialysis to evaluate metronidazole and its main metabolite concentrations in the skin after a single oral dose

OBJECTIVE: To measure the concentration of metronidazole and its hydroxymetabolite in plasma and cutaneous microdialysates and to compare metronidazole penetration into cutaneous microdialysates against theoretical predicted penetration in a peripheral compartment. METHOD: A single oral dose of 2 g of the parent drug was administered to 10 healthy male volunteers. Microdialysis probes with 2 kDa molecular weight cut-off were inserted intradermally and were perfused with Ringer solution up to 8 h after drug ingestion. Drug and metabolite concentrations were measured by high performance liquid chromatography. RESULTS: Mean maximum concentration in plasma, cutaneous microdialysates and theoretical peripheral compartment were 214 +/- 49, 151 +/- 52 and 146 +/- 38 micromol/L, respectively, and were achieved after about 2.1 +/- 0.8, 2.8 +/- 1.0 and 6.0 +/- 2.9 h. The extent of penetration into cutaneous microdialysates and theoretical peripheral compartment relative to plasma were 0.672 +/- 0.196 and 0.675 +/-0.207, respectively, and did not differ significantly. Moreover, maximum concentration as well as area under concentration-time curve in these compartments also did not differ significantly. CONCLUSION: Use of cutaneous microdialysis technique permits the characterization of true systemic drug disposition, for optimizing drug treatment strategies.     

Penetration of ciprofloxacin and its desethylenemetabolite into skin in humans after a single oral dose of the parent drug assessed by cutaneous microdialysis

OBJECTIVE: To measure the concentration of ciprofloxacin and its desethylenemetabolite in plasma and cutaneous microdialysates and to compare ciprofloxacin penetration into cutaneous microdialysates against theoretically predicted penetration in a peripheral compartment. METHOD: A single oral dose of 0.5 g of the parent drug was administered to 10 healthy male volunteers. Microdialysis probes with 2 kDa molecular weight cut-off were inserted intradermally and were perfused with Ringer solution up to 8 h after drug ingestion. Drug and metabolite concentrations were measured by high performance liquid chromatography. RESULTS: Mean maximum concentrations of ciprofloxacin in plasma, cutaneous microdialysates and theoretical peripheral compartment were 7.01+/-1.69, 2.95+/-0.64 and 3.37+/-0.60 micromol/L, respectively, and were achieved after about 2.0+/-0.6, 2.4+/-0.9 and 4.8+/-0.9 h. The extent of penetration into cutaneous microdialysates and theoretical peripheral compartment relative to plasma were 0.550+/-0.150 and 0.788+/-0.131, respectively, and differed significantly. Similarly, time to maximum concentration as well as area under the concentration-time curve in these compartments also differed significantly unlike the maximum concentration. CONCLUSION: Microdialysis permits the evaluation of the penetration of drug and its metabolites into target tissues. Such evaluation is helpful to optimize treatment strategies. After a single 0.5 g oral dose, ciprofloxacin penetrated into skin and achieved concentrations above the minimum inhibitory concentrations for susceptible pathogens, recommended by the National Committee for Clinical Laboratory Standards (NCCLS).     

Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis

Increasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l^?1). Changes in muscle blood flow were made by addition of noradrenaline (5 μg ml^?1) to the perfusion medium at two perfusion velocities (0·6 and 0·4 μl min^?1). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose‐dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose‐dependent changes in the urea clearance as well as blood‐flow‐specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0·4 compared with the 0·6 μl min^?1 perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (>90%).     

严重创伤患者SIRS评分与葡萄糖、乳酸、CRP水平的相关性分析

目的探讨严重创伤患者全身炎症反应综合征（SIRS）评分与血糖、乳酸、C反应蛋白（CRP）的相关性。方法采用美国胸科医师学会（ACCP）和美国重症医学会（SCCM）制定的SIRS诊断标准对688例严重创伤患者进行SIRS评分,检测其血葡萄糖、乳酸及CRP水平,并对它们进行相关分析。结果随着SIRS评分增加,血葡萄糖、乳酸、CRP水平也显著增高,差异有统计学意义（P〈0.05）。葡萄糖、乳酸及CRP的受试者工作特征（ROC）曲线下面积（AUC）分别为0.842、0.682、0.863。688例严重创伤患者均发生SIRS,患者SIRS评分与葡萄糖、乳酸、CRP具有明显的相关性（r分别为0.555、0.402、0.652,P〈0.05）。结论 SIRS评分及血葡萄糖、乳酸、CRP监测有助于提高严重创伤患者的抢救治疗成功率。     

Clinical determination of glucose in human serum by a tomato skin biosensor

BACKGROUND: Glucose biosensors based on enzyme reaction of glucose oxidase were studied because the symptomatic therapy of diabetes mellitus requires reliable assessment of blood glucose level at frequent intervals. Tomato skin membranes have been successfully employed to entrap glucose oxidase for fabrication of glucose biosensor. METHODS: Glucose oxidase was immobilized onto the tomato skin and the enzyme membrane was then positioned on the surface of an oxygen electrode. The glucose concentration was quantified by the change of dissolved oxygen. All the serum samples were also simultaneously determined by a Hitachi 7060 chemistry analyzer. RESULTS: The response of the biosensor showed a linear relationship with a concentration range of 1.0-30.0 mmol/l glucose. The limit of detection was 0.20 mmol/l. Error Grid analysis demonstrated that 100% of the results fell within clinically acceptable zones A and B. The F- and t-tests showed no significant differences between the 2 methods. The recovery was 95.0-110.0% for 30 serum samples analysis. CONCLUSIONS: The tomato skin biosensor possesses the advantages of simple fabrication, fast response time, low cost and high sensitivity. The results of our method are more accurate than and match well with the current clinical instrument method.     

Surface microdialysis sampling: a new approach described in a liver ischaemia model

We recently have shown that samples from microdialysis (MD) probes placed on the surface of the heart reflect metabolic events in the myocardium. This new interesting observation challenges us to consider whether surface application of MD applies to other parenchymatous organs and their surfaces. In 13 anesthetized pigs, transient liver ischaemia was achieved by occlusion of arterial and venous inflow to the liver. Two probes on liver surface and two in parenchyma were perfused with a flow rate of 1 μl per min (n = 13). An identical set-up was used for probes with a flow rate of 2 μl per min (n = 9). Samples were collected for every 15-min period during 60 min of baseline, 45 min of ischaemia and 60 min of reperfusion. Lactate, glucose, pyruvate and glycerol were analysed in MD samples. We focused on relative changes in the present study. There was a strong agreement in relative lactate and glucose levels between probes placed on liver surface and those on parenchyma. No significant differences in relative changes in lactate and glucose levels were seen between samples from surface probes and probes in liver parenchyma during equilibration, baseline, ischaemia or reperfusion with a flow rate of 1 μl per min. MD sampling applied on the liver surface is a new application area for the MD technique and may be used to monitor liver metabolism during both physiological and pathophysiological conditions.     

脓毒症患者血糖、乳酸、乳酸清除率以及碱剩余的监测及其临床应用价值

目的探讨脓毒症患者血糖、乳酸、乳酸清除率以及碱剩余的变化及其对治疗效果及预后判断的应用价值。方法测定89例脓毒症患者入院时的乳酸、碱剩余和入院6h的乳酸并计算6h乳酸清除率;动态测定血糖并选取入院后24h内测定的最差值,另外选取81例患者作为对照组。依据APACHEⅡ分值将观察组分0<20分组、21-30分组和>30分组三组,对患者的观察值进行比较,采用pearson相关分析APACHEⅡ分值与各观察值之间的相关性,另外将存活组的各观察值与死亡组对比。结果观察组的血糖、血乳酸及碱剩余与对照组相比均有统计学意义,观察组组间各观察值比较亦具有统计学意义,且随APACHEⅡ分值的增大血糖、乳酸相应增高、6小时乳酸清除率、碱剩余浓度相应下降,pearson相关分析显示血糖、血乳酸与APACHEⅡ分值呈正相关(r分别为0.594,0.713),而6小时乳酸清除率、碱剩余浓度与APACHEⅡ分值呈负相关(r分别为-0.647,-0.615),死亡组与存活组相比较A-PACHEⅡ评分与血糖、血乳酸明显增高,而6小时乳酸清除率、碱剩余明显降低,差异具统计学意义。结论血糖、乳酸、6小时乳酸清除率联合碱剩余可以综合评估脓毒症患者治疗的疗效和判断预后。     

Influence of combined intravenous and oral glucose administration on splanchnic glucose uptake in man

Summary. The influence of intravenous plus oral glucose administration on splanchnic glucose handling was examined in healthy young individuals by combining the hepatic vein catheterization technique with the double glucose tracer method. After 1 h of steady state hyperglycaemia (11·7 Itim ) induced by intravenous glucose alone (hyperglycaemic clamp technique), subjects ingested 89 ± 1 g of glucose, and the hyper-glycaemic plateau was maintained for the subsequent 4 h by adjusting the exogenous glucose infusion rate. Over the 4-h absorptive period, only 51 ± 4 g of oral glucose (i.e. 58 ±4% of the ingested load) appeared in the systemic circulation, while 193 ± 15 g (1·072±0·083 mol) of glucose had to be infused exogenously to sustain the hyperglycaemia. Endogenous glucose production was suppressed by over 60%. Net splanchnic glucose balance switched from a positive value (i.e. net uptake) of 506 ± 2–56 uniol min^-1kg^-1with intravenous glucose alone (0·60 min) to a negative one (i.e. net output) of 12·50 ± 2·44 u. mol min^-1kg^-1during 4 h (60–300 min) of intravenous+oral glucose. The mean rate of splanchnic glucose uptake was estimated to be 6·39 ±4·67 ixmol min^-1kg^-1with intravenous glucose alone, and 8·83 ±4·28 u. mol min^-1kg^-1with intravenous+oral glucose. In either case, the large majority (80–90%) of the glucose appearing in the systemic circulation was disposed of by extrasplanchnic tissues. These results indicate that pre-existing hyperglycaemia and/or hyperinsulinaemia inhibit gastrointestinal glucose absorption, and that oral glucose administration does not result in a major redistribution of intravenous glucose between splanchnic and extrasplanchnic tissues.     

Amino acid concentration in the interstitium of human skeletal muscle: a microdialysis study

BACKGROUND: The microdialysis technique has been widely used for in vivo monitoring of the interstitial composition of several tissues. Remarkably high concentrations of taurine and glycerol were reported in a recent human study. As taurine and glycerol are predominantly present in the intracellular space, cellular trauma after probe insertion may have resulted in elevated interstitial concentrations. With the present study we wanted to investigate the impact of the initial trauma on the interstitial concentrations of amino acids and glycerol. METHODS: Microdialysis probes were inserted into the vastus lateralis muscle in eight subjects. Using a slow perfusion rate of 0.3 muL min-1, dialysate samples were collected in five 75-min periods. Simultaneously, plasma samples were taken from a peripheral vein for amino acid determination. RESULTS: During the first collection period, the dialysate concentration for 21 measured amino acids was on average 180% +/- 51% higher than the concentration in plasma water. This difference decreased to 52% +/- 15%, 32% +/- 8%, 37% +/- 8% and 31% +/- 7% during periods 2, 3, 4 and 5 respectively. Carnosine, which is not present in plasma, was detected in high concentrations in the interstitium during the first collection period and decreased subsequently. CONCLUSION: In the post-absorptive phase, the concentrations of most amino acids in muscle interstitium are slightly higher than in venous plasma water. The leakage of intracellular amino acids, because of probe insertion, will initially lead to an overestimation of the actual interstitial concentration of amino acids. Therefore, reliable baseline values of amino acids cannot be obtained until 120-150 min after probe insertion. The dialysate concentration of carnosine may be used as a marker of cellular leakage.     

Lactate balance in perfused rat liver: Effects of glucose concentration,flow and low pH on glucose to lactate flux

The effects of medium glucose concentration (0-20 mmol 1^?1), pH (7.4 and 6.8) and flow (100 to 33% normal) on lactate uptake and glycolytic flux from 6-³H glucose were studied in perfused livers from 48-h starved rats. At both pH values, the glycolytic flux increased proportionally with the medium glucose concentration. Maximum glycolytic flux at 20 mmol L¹ glucose in the medium was 0.5 umol mirT¹ g^?1 liver (C₆-units) at pH 7.4. At pH 7.4 and 20 mmol 1^?1 glucose the glycolytic flux decreased approximately proportional with flow. At pH 6.8 the glycolytic flux was extremely low and independent of flow. At flow 33% normal and pH 7.4 a net lactate production was accounted for by glycolysis from medium glucose concentration, indicating virtually no simultaneous lactate uptake. In contrast, at pH 6.8 net lactate production accounted for only half the glycolytic rate, indicating that lactate uptake occurred simultaneously with glycolysis. Thus, glucose-to-lactate flux in liver (as in muscle and brain) is subject to inhibition by low pH, and lactate uptake is enhanced by low pH.     

Changes in coronary haemodynamics and myocardial metabolism at rest and during exercise after a cardiotonic drug (prenalterol) in patients with coronary artery disease

Summary. To elucidiate the myocardial metabolic and haemodynamic effects of an inotropic drug in patients with coronary artery disease (CAD) without evident congestive heart failure (CHF), the acute effects of prenalterol were studied in nine patients. Patients with documented CAD by leftsided cardioangiography and end-diastolic pressure >15 mm Hg were included in the study. They were examined at rest and during supine exercise at a level just below their anginal threshold before and after prenalterol. At rest, rate pressure product (RPP) increased by 40% (P<0·01), cardiac index rose 20% (P<0·01), cardiac venous flow (CVF) increased by 18% (P<0·05), and myocardial oxygen consumption (MVO₂) increased by 20% (P<0·05) after prenalterol administration. Despite a decrease in mean pulmonary capillary venous pressure (PCV) of 40% (P<0·01), myocardial lactate extraction fell significantly (P<0·01) and lactate production was observed in three of nine patients compared to before prenalterol administration. During exercise, RPP increased by 20% (P<0·01), cardiac index remained unchanged, CVF increased by 25% (NS) and MV0₂ showed a tendency to an increase (NS) after prenalterol administration. Mean PCV pressure decreased by 30% (P<0·01). Myocardial lactate extraction was markedly reduced during exercise (P<0·01) and five of nine patients showed lactate production compared to that before prenalterol administration. Thus, despite a decrease in left ventricular filling pressure, increased myocardial oxygen demand occurred after acute administration of prenalterol. Prenalterol and probably similar inotropic drugs should be used cautiously in patients with CAD without clinical evidence of congestive heart failure.     

Effects of salbutamol and BRL 37344 on diastolic arterial blood pressure, plasma glucose and plasma lactate in rabbits

Summary— The aim of this study was to investigate in rabbits the diastolic arterial blood pressure, plasma glucose and plasma lactate responses to salbutamol (a selective beta-2 adrenoceptor agonist) and BRL 37344 (a selective beta-3 adrenoceptor agonist) in comparison with CGP 12177 (a potent beta-1 and beta-2 adrenoceptor antagonist which also acts as a partial beta-3 agonist), isoprenaline (a non-selective beta-1, beta-2 and beta-3 adrenoceptor agonist) and adrenaline (a non-selective beta and alpha adrenoceptor agonist). All drugs were iv infused at the same dose: 0.3 μg/kg/min (30 min). In sodium pentobarbitone (40 mg/kg)-anasthetized animals none of these compounds altered diastolic arterial blood pressure. BRL 37344 (0.1, 0.3, 1 μg/kg/min) did not modify this parameter either. In conscious 24-h fasted rabbits, only adrenaline was able to increase plasma glucose levels. By contrast, under the same experimental conditions, salbutamol, isoprenaline and adrenaline, but not BRL 37344 or CGP 12177, induced a significant increase in plasma lactate levels. Finally, the salbutamol-mediated plasma lactate response was inhibited in the presence of clonidine (2 μg/kg/min, an alpha-2 adrenoceptor agonist), a drug considered to have opposite effects (stimulatory and inhibitory) on the adenylate cyclase system. In conclusion, these data suggest that only beta-2 adrenoceptor stimulation is able to increase plasma lactate levels, a response which is inhibited by alpha-2 adrenoceptor stimulation.     

Depletion of myocardial glucose is observed during endotoxemic but not hemorrhagic shock in a porcine model

Introduction

Metabolic dysfunction is one of the hallmarks of sepsis yet little is known about local changes in key organs such as the heart. The aim of this study was to compare myocardial metabolic changes by direct measurements of substrates, such as glucose, lactate and pyruvate, using microdialysis (MD) in in-vivo porcine endotoxemic and hemorrhagic shock. To assess whether these changes were specific to the heart, we simultaneously investigated substrate levels in skeletal muscle.

Methods

Twenty-six female pigs were randomized to three groups: control (C) n = 8, endotoxemic shock (E) n = 9 and hemorrhagic shock (H) n = 9. Interstitial myocardial pyruvate, lactate and glucose were measured using MD. Skeletal muscle MD was also performed in all three groups.

Results

Marked decreases in myocardial glucose were observed in the E group but not in the H group compared to controls (mean difference (CI) in mmol/L: C versus E -1.5(-2.2 to -0.8), P <0.001; H versus E -1.1(-1.8 to -0.4), P = 0.004; C versus H -0.4(-1.1 to 0.3), P = 0.282). Up to four-fold increases in myocardial pyruvate and three-fold increases in lactate were seen in both shock groups with no differences between the two types of shock. There was no evidence of myocardial anaerobic metabolism, with normal lactate:pyruvate (L:P) ratios seen in all animals regardless of the type of shock.In skeletal muscle, decreases in glucose concentrations were observed in the E group only (mean difference: C versus E -0.8(-1.4 to -0.3), P = 0.007). Although skeletal muscle lactate increased in both shock groups, this was accompanied by increases in pyruvate in the E group only (mean difference: C versus E 121(46 to 195), P = 0.003; H versus E 77(7 to 147), P = 0.032; C versus H 43(-30 to 43), P = 0.229). The L:P ratio was increased in skeletal muscle in response to hemorrhagic, but not endotoxemic, shock.

Conclusions

Endotoxemia, but not hemorrhage, induces a rapid decrease of myocardial glucose levels. Despite the decrease in glucose, myocardial lactate and pyruvate concentrations were elevated and not different than in hemorrhagic shock. In skeletal muscle, substrate patterns during endotoxemic shock mimicked those seen in myocardium. During hemorrhagic shock the skeletal muscle response was characterized by a lack of increase in pyruvate and higher L:P ratios.Hence, metabolic patterns in the myocardium during endotoxemic shock are different than those seen during hemorrhagic shock. Skeletal muscle and myocardium displayed similar substrate patterns during endotoxemic shock but differed during hemorrhagic shock.     

Metabolic and hormonal changes after surgery: hyperinsulinaemia during glucose infusion

Abstract. Serial measurement of blood and urinary hormones and metabolites were made on eleven patients before and after abdominal surgery. A complete nitrogen balance on three patients showed that after the operation there was a net loss of nitrogen equivalent to about 50 g protein per day for 5–6 days.
This period coincided with elevated fasting plasma levels of glucagon and non-esterified fatty acids (NEFA), and elevated 24 h urinary excretion of free cortisol and 17OH-corticosteroids; total plasma amino acid levels were diminished but the concentrations of the branchedchain amino acids were increased. Fasting plasma concentrations of glucose, insulin and cortisol were increased only on day 1 after the operation. A 2 h glucose infusion (0.35 g kg^-1 h^-1) was carried out on each patient on day 1 and on 'recovery' (9–21 days). The mean glucose levels reached (12.1 mmol and 10.3 mmol/l, respectively) did not differ significantly; they were much higher than in young normal subjects (6.1 mmol/l). Glucose infusions, both on day 1 and on 'recovery' resulted in significant depression of glucagon and NEFA levels. Plasma insulin levels during glucose infusion were significantly higher on day 1 than on 'recovery', suggesting improving sensitivity to insulin. Possible explanations are discussed. Attention is drawn to the practical implications of the choice of nutrients in the parenteral nutrition of postoperative patients.     

重症颅脑外伤急性期联合检测空腹血糖和糖化血红蛋白及乳酸脱氢酶临床价值

目的探讨联合检测空腹血糖（fasting plasma glucose,FPG）、糖化血红蛋白（glycosylated hemoglobin A1C,HbA1c）及乳酸脱氢酶（1actate dehydrogenass,LDH）在重症颅脑外伤急性期患者病情评估及预后判断中的价值。方法52例重症颅脑损伤患者,分别依据人院时格拉斯哥昏迷评分（GlasgowComaScale,GCS）、FPG联合HbAtc检测情况及GCS预后评分进行分组,比较重度颅脑损伤组（GCS评分6～8分）与极重度颅脑损伤组（GCS评分3～5分）、糖尿病高血糖组（FPG〉6．1mmol／L且HbAlc〉6．2％）与应激性高血糖组（FPG〉6．1mmol／L且HbAlc〈6．2％）及不同预后患者LDH、FPG水平,并分析GCS评分与LDH、FPG的相关性。结果极重度颅脑损伤组FPG、LDH水平高于重度颅脑损伤组（P〈O．01）;糖尿病高血糖组与应激性高血糖组FPG、LDH水平及预后比较差异无统计学意义（P〉0．05）;恢复良好组、预后差组、死亡组LDH、FPG水平比较差异均有统计学意义（P〈0．01）;重症颅脑外伤患者人院时GCS评分与LDH、FPG水平呈负相关（r=-0．948,P=0．001;r=-0．941,P=0．001）。结论FPG、LDH可用于评估颅脑损伤严重程度,判断患者预后,HbA,c在鉴别诊断糖尿病性或应激性血糖增高中有重要价值。