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Biomedical subjects

T Schricker

Publications and source records attributed to T Schricker.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Clonidine compared to midazolam for intravenous premedication for ambulatory procedures. A controlled double blind study in ASA 1 patients].

OBJECTIVE: Midazolam is frequently used for premedication in day-case surgical patients whereas clonidine is rarely administered for this indication. However, clonidine has several useful effects that make the drug an interesting alternative to conventional premedicants. Thus, in this randomised, double-blind, and controlled study the anxiolytic effect of midazolam was compared to that of clonidine. Furthermore, effects on postoperative complaints and minor complications, and readiness for discharge were investigated. METHODS: 100 ASA-1 patients undergoing wisdom teeth extraction on a day-case basis were included into the analysis. A further 50 patients who received no premedication served as a control group. General anaesthesia was standardised (propofol-fentanyl-isoflurane in N2O/O2). The anxiolytic effect of the premedication was assessed using the Erlanger anxiety- and tension scale (EAS). The test was applied before and after intravenous premedication with 1.5 micrograms/kg clonidine or 50 micrograms/kg midazolam and repeated once postoperatively. During recovery the incidence and severity of pain, nausea and vomiting, and shivering were recorded. The readiness for discharge was assessed using standardised discharge criteria. The recording of data was completed by a telephone interview on the day after surgery. RESULTS: The demographic data of the groups did not differ. In the two treatment groups there was a time-dependent decrease of anxiety and tension. However, postoperatively there was no difference between the levels of anxiety and inner tension between the premedicated patients and the untreated control group. Furthermore there was no difference in the incidence and severity of any postoperative complications. Time until the patients were ready for discharge did not differ between the three groups. CONCLUSION: The effects of an intravenous premedication with 1.5 micrograms/kg clonidine or 50 micrograms/kg midazolam, respectively in young ASA-1 patients undergoing minor surgical procedures on a day-case basis are restricted to decrease of anxiety and inner tension before surgery. No beneficial effects were found during the postoperative period compared with untreated control patients.

Adjuvants, Anesthesia↗
PubMed2000

Propofol/sufentanil anesthesia suppresses the metabolic and endocrine response during, not after, lower abdominal surgery.

UNLABELLED: We investigated the influence of propofol/sufentanil anesthesia on metabolic and endocrine responses during, and immediately after, lower abdominal surgery. Twenty otherwise healthy patients undergoing abdominal hysterectomy for benign myoma received either continuous infusions of propofol supplemented with sufentanil (0.01 microg. kg(-1). min(-1), n = 10) or enflurane anesthesia (enflurane, n = 10). Plasma concentrations of glucose, lactate, free fatty acids, triglycerides, insulin, glucagon, cortisol, epinephrine, and norepinephrine were measured before, during, and 2 h after surgery. Pre- and postoperative endogenous glucose production (R(a) glucose) was analyzed by an isotope dilution technique by using [6,6-(2)H(2)] glucose. Propofol/sufentanil anesthesia prevented the increase in plasma cortisol and catecholamine concentrations and attenuated the hyperglycemic response during surgery without showing any difference after the operation. Mediated through a higher glucagon/insulin quotient (propofol/sufentanil 15 +/- 7 versus enflurane 8 +/- 4 pg/microU, P < 0.05), the R(a) glucose postoperatively increased more in the propofol/sufentanil than in the enflurane group (propofol/sufentanil 15.6 +/- 2.0 versus enflurane 13.4 +/- 2.2 micromol. kg(-1). min(-1), P < 0.05). IMPLICATIONS: The concept of stress-free anesthesia using propofol combined with sufentanil is valid only during surgery. The metabolic endocrine stress response 2 h after the operation is more pronounced than after inhaled anesthesia.

Anesthesia, Intravenous↗
PubMed2000

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.

Adult↗
PubMed2000

Epidural blockade improves substrate utilization after surgery.

The purpose of this study was to test the hypothesis that epidural blockade with local anesthetic improves the anticatabolic effects of glucose after colorectal surgery. Sixteen patients were randomly assigned to undergo a 6-h stable isotope infusion study (3 h fasted, 3 h glucose infusion at 4 mg. kg(-1). min(-1)) on the second postoperative day with or without perioperative epidural blockade. Protein synthesis, breakdown and oxidation, and glucose production and clearance were assessed by L-[1-(13)C]leucine and [6, 6-(2)H(2)]glucose. Epidural blockade did not affect protein and glucose metabolism in the fasted state. Glucose infusion increased glucose clearance (P < 0.05), accompanied by an increase in the respiratory quotient (P < 0.05) and a decrease in leucine oxidation (P < 0.05) only in the presence of epidural blockade. An inverse correlation (r = -0.74, P < 0.05) between changes in glucose clearance and leucine oxidation was observed. In conclusion, epidural blockade facilitates whole body glucose uptake and inhibits endogenous protein oxidation after abdominal surgery, indicating a shift from a protein to a more glucose-dominated substrate utilization.

Aged↗
PubMed1999

Time of peritoneal cavity exposure influences postoperative glucose production.

PURPOSE: To examine the effect of the duration of peritoneal cavity exposure on glucose metabolism after abdominal surgery. METHODS: In eight otherwise healthy patients (ASA 1) with uterine myoma, endogenous glucose production (Ra glucose) was measured immediately before and two hours after abdominal hysterectomy by a stable isotope dilution technique using primed continuous infusions of [6,6-2H2]-glucose. Plasma concentrations of glucose, lactate, insulin, glucagon, cortisol, epinephrine and norepinephrine were determined before, during (5 and 60 min after peritoneal incision, skin closure) and two hours after surgery. Pre- and postoperative glucose clearance was calculated as Ra glucose divided by plasma glucose concentration. RESULTS: Ra glucose increased from 11.8 +/- 1.2 to 16.8 +/- 3.2 micromol x kg(-1) x min(-1) two hours after hysterectomy (P < 0.05) with a correlation between the degree of increase and the time of peritoneal cavity exposure (r = 0.859, P = 0.006). Plasma glucose concentration increased after surgery from 4.7 +/- 0.8 to 8.3 +/- 1.9 mmol x l(-1) (P < 0.05), while glucose clearance decreased from 2.6 +/- 0.4 to 2.1 +/- 0.4 ml x kg(-1) x min(-1) (P < 0.05). Plasma concentrations of cortisol and catecholamines increased after hysterectomy (cortisol from 6 +/- 2 to 31 +/- 7 microg x dl(-1), epinephrine from 25 +/- 14 to 205 +/- 132 pg x ml(-1), norepinephrine from 182 +/- 82 to 377 +/- 132 pg x ml(-1), P < 0.05), whereas plasma lactate, insulin and glucagon concentrations remained unchanged. CONCLUSION: The magnitude of increase of glucose production after abdominal hysterectomy is associated with the duration of peritoneal cavity exposure.

Adult↗
PubMed1999

The independent effect of propofol anesthesia on whole body protein metabolism in humans.

BACKGROUND: The purpose of this study was to examine the effect of general anesthesia with propofol in the absence of surgical stimulation on whole body protein metabolism. METHODS: Six unpremedicated patients were studied. General anesthesia included propofol (120 microg x kg(-1) x min(-1)), vecuronium bromide, and oxygen-enriched air. Changes in protein breakdown, protein oxidation, and synthesis were measured by an isotope dilution technique using a constant infusion of the stable isotope tracer L-[1-13C]leucine (0.008 mg x kg(-1) x min(-1)) before and during 100 min of propofol anesthesia. The plasma concentrations of glucose, lactate, non-esterified fatty acids, and cortisol were measured before and during anesthesia. RESULTS: An isotopic steady state of plasma [1-13C]alpha-ketoisocaproate (taken to represent the intracellular leucine precursor pool enrichment for protein synthesis) and expired 13C-carbon dioxide were obtained before and during propofol infusion. Whole body protein breakdown decreased during propofol anesthesia by 6% (P < 0.05), whereas protein synthesis and oxidation did not change significantly. Plasma concentration of cortisol decreased after 90 min of propofol anesthesia (P < 0.05). No significant changes of plasma concentrations of glucose, lactate, and non-esterified fatty acids occurred during propofol administration. CONCLUSIONS: Propofol anesthesia did not significantly affect whole body protein synthesis and oxidation but caused a small, although significant, decrease in whole body protein breakdown, possibly mediated through the suppression of plasma cortisol concentration.

Adult↗
PubMed1997

[Liver urea and glucose production in patients with alcohol-induced cirrhosis].

OBJECTIVE: To use stable isotopes for the analysis of hepatic metabolic pathways (urea synthesis, glucose production), comparing them in alcoholic and normal liver, in order to obtain specific and quantitative information on metabolic functions of the liver. PATIENTS AND METHODS: Urea and glucose production as well as alanine metabolism in the liver were studied by means of stable isotopes in 7 males with alcoholic liver cirrhosis (mean age 46 +/- 4 years; height 173 +/- 5 cm; weight 73 +/- 3 kg) and 7 healthy male volunteers as controls (age 26 +/- 3 years; height 180 +/- 5 cm; weight 75 +/- 6 kg). The plasma concentrations of adrenaline, noradrenaline, insulin, glucagon and amino-acids were also measured. RESULTS: Urea synthesis was lower in the cirrhosis patients than in the controls (3.3 +/- 2.2 mumol/kg.min vs 4.8 +/- 0.9 mumol/kg.min, P < 0.05). But there were no differences in glucose production, alanine metabolism and adrenaline concentrations. The concentrations of glutamine, phenylalanine, tyrosine, insulin, glucagon and noradrenaline were significantly raised in the cirrhotic patients, those of valine and leucine significantly lower. CONCLUSIONS: Contrary to hepatic glucose production, which was within normal limits, urea synthesis was reduced by 30% in the cirrhotic patients. The use of stable isotopes provided detailed information on specific metabolic processes in cirrhotic livers.

Adult↗
PubMed1997

[Parenteral nutrition therapy. Energy and non-energy actions of carbohydrates and fats].

The object of this review is to demonstrate the non-nutritional importance of carbohydrates and fat as they represent the classic energy carriers in parenteral nutrition. Concerning the pathophysiological changes of organ metabolism and intermediary metabolism as well as the pharmacological function of this nutritive substrates it is necessary to adjust parenteral nutrition strategy to various clinical pictures. The major goals of parenteral applicated carbohydrates are to avoid hyperglycemia, to return the increased hepatic glucose production during trauma and sepsis back to normal, and to reduce protein catabolism. Realizing this goals the dosage of glucose infusion underlies close metabolic borders depending on the present disease. Because of favourable effects of hepatic glucose and protein metabolism, xylitol, a non-glucose polyol, represents an useful alternative energy source to glucose. The non-energetic nutrition therapy with fat consists of application of the essential fatty acids linoleic and alpha-linolenic acid and considers the immunmodulatory effects of various fatty acids as precursors in the eicosanoid metabolism. As demonstrated at the organ systems of liver and lung this pharmacological effects of any lipid infusion might influence specific organ functions.

Animals↗
PubMed1997

Assessment of perioperative glycerol metabolism by stable isotope tracer technique.

The aim of this study was to investigate metabolic changes during and after abdominal hysterectomy with specific regard to glycerol metabolism. Seven otherwise healthy patients with benign uterine myoma were enrolled in this study. Glycerol turnover and hepatic glucose production were measured before and after the operation by using stable-isotope technique ([1,1,2,3,3-2H5]-glycerol, [6,6-2H2]-glucose). Metabolic substrates (glycerol, nonesterified fatty acids, beta-hydroxybutyrate, glucose, lactate) and hormones (insulin, glucagon, cortisol, catecholamines) were determined pre-, intra- and postoperatively. Hysterectomy was associated with an increase of postoperative glycerol turnover from 3.56 +/- 1.28 to 6.46 +/- 2.44 mumol.kg-1.min-1 (P < 0.05). This increment was inversely related to the age of the patients (r = 0.872, P < 0.05). Glycerol concentration tended to increase perioperatively. These changes, however, were not of statistical significance. Hepatic glucose production and glucose plasma levels increased postoperatively from 9.75 +/- 1.61 to 12.79 +/- 1.45 mumol.kg-1.min-1 (P < 0.05) and 4.6 +/- 0.9 to 6.2 +/- 0.9 mmol/L (P < 0.05), respectively. Cortisol and catecholamine levels rose during and after surgery, while insulin and glucagon remained unchanged. The enhanced rate of lipolysis after hysterectomy was not detectable from plasma glycerol levels alone. The results of this study showed that using stable isotope technique allowed a more differentiated look at metabolic pathways than static plasma substrate concentrations, especially under perioperative conditions.

Adult↗
PubMed1996

Effects of epinephrine on glucose metabolism in patients with alcoholic cirrhosis.

The cirrhotic liver has been shown to be resistant to the actions of various glucoregulatory hormones. The objective of this study was to investigate the effects of epinephrine on hepatic glucose metabolism in cirrhotic patients. Thirteen cirrhotic and eight healthy subjects were studied. Hepatic glucose production and turnover of alanine and glycerol were measured using stable isotope technique before and during 70 and 150 minutes of epinephrine infusion (0.1 microgram/kg/min). beta-Adrenoreceptor binding sites and affinity in mononuclear leukocyte membranes also were determined. Hepatic glucose production and alanine turnover in normals significantly increased during epinephrine infusion, but did not change in cirrhotics. Glycerol turnover increased after 70 minutes of epinephrine infusion in both groups. Epinephrine induced a significant rise of high-affinity beta-adrenoreceptor binding sites in normals, yielding a significant correlation between hepatic glucose production and receptor density (r = .94, P < .0001). In cirrhotic patients, similar changes in the number of high-affinity beta-adrenoreceptors were observed, but no correlation with hepatic glucose production was detected. The cirrhotic liver did not respond normally to the stimulatory effect of epinephrine on hepatic glucose production. Because this blunted response was not related to changes of beta-adrenoreceptors, our findings suggest that epinephrine resistance in cirrhosis was caused by a postreceptor defect.

Adult↗
PubMed1996

[Changes in various metabolic parameters following bloodletting].

OBJECTIVE: We investigated hypovolaemia induced by bloodletting, accompanied by statistically significant, but clinically irrelevant increase of heart rate together with unchanged blood pressure, with regard to hepatic glucose production as well as alanine and glycerol turnover rates. METHODS: Healthy male volunteers (n = 18) were bled 15 ml/kg body weight over 20 min and remained hypovolaemic for 60 minutes. Heart rate was recorded by ECG and blood pressure by an oscillometric device. Before and after bloodletting hepatic glucose production as well as alanine and glycerol turnover rates were determined using the stable isotopes 6.6-D2-glucose, 15N-alanine and D5-glycerol as tracers. Simultaneously, the blood concentrations of adrenaline, noradrenaline, free fatty acids and glycerol were measured. RESULTS: Bleeding did not change the mean arterial blood pressure, but increased the heart rate significantly from 61 +/- 9 to 70 +/- 13 1/ min. Noradrenaline levels increased significantly from 1.16 +/- 0.41 to 2.15 +/- 0.69 nmol/l. Hepatic glucose production (HGP) as well as alanine (AlaTO) and glycerol turnover (GlyTO) decreased significantly during hypovolaemia. HGP fell from 2.72 +/- 0.29 to 2.56 +/- 0.28 mg/kg/min, AlaTO from 0.71 +/- 0.27 to 0.53 +/- 0.25 mg/kg/min and GlyTO from 4.9 +/- 2.1 to 3.8 +/- 1.4 mumol/kg/min, respectively. The blood levels of adrenaline, free fatty acids and glycerol did not change during the study. DISCUSSION: In respect of clinical signs, the cardiovascular status of the volunteers was stable after bleeding. In contrast, the decrease of HGP as well as the drop in alanine and glycerol turnover rates might be interpreted as a sign of an altered functional status of single organs, induced by changes of regional perfusion.

Adult↗
PubMed1996

Influence of vaginal versus abdominal hysterectomy on perioperative glucose metabolism.

The aim of this study was to investigate the metabolic effects of abdominal versus vaginal hysterectomy with specific regard to perioperative glucose metabolism. Fourteen patients received either abdominal (AH, n = 7) or vaginal hysterectomy (VH, n = 7). Hepatic glucose production was measured before and 2.5 h after the operation by stable isotope technique ([6,6-2H2]-glucose). Metabolic substrates (glucose, lactate, nonesterified fatty acids [NEFA], beta-hydroxybutyrate) and hormones (insulin, glucagon, cortisol, catecholamines) were determined pre-, intra-, and postoperatively. VH induced a higher postoperative glucose concentration than the abdominal approach (VH, 148 +/- 25 mg/dL; AH, 111 +/- 16 mg/dL; P < 0.05). Since postoperative enhancement of hepatic glucose production was comparable in both groups, glucose clearance was lower after the vaginal procedure (VH, 1.7 +/- 0.3 mL.kg-1.min-1; AH, 2.1 +/- 0.3 mL.kg-1.min-1; P < 0.05). NEFA, beta-hydroxybutyrate, and catecholamines similarily increased after surgery. Cortisol levels were more increased after VH (VH, 80 +/- 26 micrograms/dL; AH, 37 +/- 14 micrograms/dL; P < 0.001). Lactate, glucagon, and insulin concentrations did not change perioperatively. The more pronounced hyperglycemic response to VH was due to lower peripheral glucose use caused by higher postoperative cortisol values. The mechanisms responsible for this marked cortisol enhancement after the vaginal operation as well as the clinical significance for patients with preexisting impaired carbohydrate tolerance, however, remained unclear and warrant further investigation.

3-Hydroxybutyric Acid↗
PubMed1996

Effects of selective phosphodiesterase 3 inhibition in the perfused liver of the rat after endotoxin treatment.

1. This study was designed to investigate the role of rat phosphodiesterase 3 (RPDE3) in regulation of liver metabolism in sepsis. We studied the effects of the phosphodiesterase 3 inhibitor (PDI), enoximone, alone and in combination with regulating factors of hepatic carbohydrate metabolism and bile secretion in the perfused liver of rats treated 4 h earlier with endotoxin. In addition, cyclic AMP and cyclic GMP levels were determined in the effluate and bile by radio immunoassay methods. 2. After endotoxin treatment, infusion of enoximone at three concentrations (1 microM, 10 microM) resulted in an increased glucose output from -1.4 +/- 0.9 to 7.8 +/- 2.5 mumol l-1 20 min-1. Bile acid-independent bile flow increased also, in a dose-dependent manner. 3. In untreated livers, cyclic AMP release increased in the effluate from 1000 +/- 73 fmol g-1 min-1 to 1710 +/- 143 fmol g-1 min-1 when enoximone (10 microM) was administered. In bile from untreated livers, the level of cyclic AMP was also significantly increased by enoximone. After endotoxin treatment, the enoximone (10 microM) effect on cyclic AMP levels in effluate and bile was greatly reduced. Levels of cyclic GMP in the effluate and bile appeared unchanged in the presence of enoximone. 4. During co-infusion of glucagon (1 nM) and enoximone (10 microM), cyclic nucleotide levels in the effluate and bile of livers after endotoxin treatment were determined. In the effluate, cyclic AMP release increased from 827 +/- 144 fmol g-1 min-1 to 17802 +/- 2821 fmol g-1 min-1 when glucagon was administered. The presence of enoximone enhanced cyclic AMP further to 41696 +/- 920 fmol g-1 min-1. The same changes in cyclic AMP release were found in bile. Levels of cyclic GMP in the effluate and bile were not significantly affected by the administration of glucagon and the PDI. 5. Glucose release was determined during glucagon, sympathetic nerves stimulation and phenylephrine administration in the presence and absence of enoximone. The addition of enoximone to glucagon increased glucose release by 8.2 +/- 2.8 mumol g-1 20 min-1, without alteration of lactate balance. The PDI enhanced the glycogenolytic effects of nerve stimulation and of phenylephrine, accompanied by a reduction in lactate production. 6. Enoximone significantly enhanced the bile acid independent bile flow after glucagon, nerves stimulation and after administration of phenylephrine. Bile acid secretion was unaffected by the PDI. The vasoconstrictor effect of nerve stimulation was reduced by the PDI. 7. We conclude that endotoxin treatment reduces the ability of the PDI, enoximone, to increase cyclic AMP release in the perfused liver. The significant increase in cyclic AMP release after stimulation with glucagon and enoximone favours the view that RPDE3 is involved in the degradation of cyclic AMP in the liver after exposure to endotoxin. Additionally, the inhibition of the RPDE3 results in glucose release, vasodilatation and choleresis in endotoxin pretreated livers.

Animals↗
PubMed1995

Enhancement of hepatic glucose release and bile flow by the phosphodiesterase-III-inhibitor enoximone in the perfused rat liver.

The use of phosphodiesterase-III-inhibitors (PDI) as inotropic substances in the treatment of cardiac failure can be associated with hyperglycaemia. This phenomenon could be caused by hepatic events induced by PDI. The purpose of our study was to investigate the effects of the PDI enoximone on hepatic carbohydrate metabolism and bile flow. In the rat liver perfusion model, hepatic glucose and lactate production, portal flow and bile flow were determined. Administration of enoximone (1, 10, 100 microM) increased hepatic glucose output and bile acid-independent bile flow in a dose-dependent manner. The PDI enhanced the glycogenolytic effects of glucagon (from 15.7 to 38.6 mumol glucose/g/20 min), of epinephrine (from 7.1 to 38.7 mumol glucose/g/20 min), of norepinephrine (from 9.8 to 32 mumol/g/20 min) and of phenylephrine (from 25.5 to 40.8 mumol glucose/g/20 min). Furthermore, lactate production was significantly reduced by enoximone. The effect of epinephrine and phenylephrine on portal flow was blocked or diminished by enoximone administration. In summary, it was shown that the PDI enoximone is able to enhance hepatic glucose production. Bile acid-independent bile flow was increased by the inhibition of phosphodiesterase-III. The effects of enoximone and glycogenolytic hormones on glucose release were synergistic. The vasoconstrictive action of catecholamines was reduced or completely prevented by enoximone. In conclusion, enoximone has glycogenolytic, vasodilatory and choleretic properties in the liver.

Animals↗
PubMed1995

Glycerol metabolism in patients with alcohol-induced liver cirrhosis.

The clearance rate of glycerol has been found to be impaired in alcoholic liver disease. However it remains unclear, if this can be ascribed to a defect of hepatic gluconeogenesis. Thus, the purpose of this work was to investigate glycerol clearance and hepatic glucose production in patients with liver cirrhosis. 13 patients with alcohol-induced Child B cirrhosis and 8 healthy volunteers were studied. Rates of appearance (R(a)) of glycerol, glucose and alanine were determined using stable isotope techniques. In addition indocyanine green clearance (ICGC) and plasma substrate concentrations were measured. Clearance rates were calculated as R(a) divided by the corresponding substrate concentration. R(a) of glycerol in patients was not different from controls, but glycerol clearance was significantly reduced (29 +/- 3 vs. 41 +/- 4 ml/kg/min). No differences in R(a) of glucose and alanine and corresponding plasma concentrations were observed. ICGC in patients was about 35% lower than reference values. Diminished glycerol clearance in patients with liver cirrhosis was not due to impaired hepatic gluconeogenesis. Since glycerol is almost completely extracted by the liver decreased glycerol clearance possibly simply reflected compromised liver perfusion as seen by reduced ICGC.

Journal Article↗
PubMed1995

Effects of PEEP ventilation on liver metabolism.

OBJECTIVE: To study the influence of positive endexpiratory pressure (PEEP) ventilation on metabolic parameters with specific regard to liver metabolism. DESIGN: Prospective experimental study on the effects of PEEP ventilation on hemodynamic and gas exchange as well as metabolic parameters, i.e. hepatic glucose production, arterial, hepatic and portal venous insulin, glucagon, free fatty acid (FFA), glycerol, beta-hydroxybutyrate and lactate concentrations. SETTING: Experimental Laboratory Unit of the University Hospital. ANIMALS: 10 Labrador Beagle dogs (18-22 kg) were studied. INTERVENTIONS: Animals were ventilated with PEEP of 0, 7.5, 15, and 0 mm Hg, each level lasting 2 h. RESULTS: PEEP 15 significantly increased heart rate from 110(70) to 220(55) beats/min and decreased cardiac output from 2.5 (2.0) to 1.5 (0.8) l/min. This was associated with significant increases in mean pulmonary artery pressure, pulmonary artery occlusion pressure, portal and hepatic venous pressure, whereas mean systemic pressure did not change. While whole-body oxygen consumption and respiratory quotient remained constant, whole-body oxygen delivery significantly decreased from 456(266) to 294(168) ml/min during PEEP 15 concomitant to augmented whole-body oxygen extraction (from 27(34) to 51(33)%). Oxygen extraction from the splanchnic organs increased from 41(31) to 81(30)%. Hepatic venous oxygen tension (PhvO2) and hemoglobin oxygen saturation (ShvO2) during PEEP 15 decreased from 41(18) to 28(47) mm Hg and from 60(31) to 18(66)%, respectively. Hepatic glucose production was significantly stimulated from 3.44(1.44) to 3.92(1.83) mg/kg/min at PEEP 15. Arterial and portalvenous glucagon/insulin ratios did not change. FFA and glycerol concentrations depending on PEEP levels were significantly higher in the hepatic artery and portal vein than in the hepatic vein. Compared to portal venous and arterial hepatic concentrations, hepatic venous beta-hydroxybutyrate significantly increased with rising PEEP levels. CONCLUSIONS: Low values of PhvO2 and ShvO2 during PEEP 15 gave evidence for hypoxia of the liver. This was associated with a stimulated hepatic glucose production rate accompanied by enhanced hepatic uptake and utilization of FFA serving as fuel substrates. As the rate of gluconeogenesis is a major determinant of hepatic oxygen consumption these metabolic effects of PEEP ventilation have to be considered during states of critical illness.

Animals↗
PubMed1994

[Perioperative endothelin, ACTH and cortisol plasma concentrations in coronary bypass patients].

STUDY OBJECTIVE: To follow up endothelin (ET), adrenocorticotropic hormone (ACTH), and cortisol levels in patients undergoing aortocoronary bypass grafting (CABG) and to determine whether these are extracted from plasma by the pulmonary circulation. DESIGN: Convenience sample trial. SETTING: University hospital. PATIENTS: Eight male routine CABG patients without appreciable concomitant disease. INTERVENTIONS: Patients were given anaesthesia in a strictly standardised manner using etomidate, flunitrazepam, fentanyl, and pancuronium. Nitroglycerin was administered prior to cardiopulmonary bypass (CPB) at 2 mg/h and dopamine as the only catecholamine starting from CPB weaning until the end of sampling at 3.5-5 micrograms/kg.min. Samples were drawn in rapid sequence from cannulated radial and a distal pulmonary arteries (Swan-Ganz catheter) at eight sampling times starting after induction of anaesthesia and catheter placement and finishing 22 h after the end of operation. MEASUREMENTS AND RESULTS: ET levels were determined by an ET-1, 2, 3-sensitive radioimmunoassay (RIA), ACTH and cortisol by commercially available RIA kits. There was significant (P = 0.032, linear regression analysis) correlation between ET and cortisol from pulmonary arterial samples. ET was significantly (P = 0.042, two-tailed Wilcoxon test) extracted by the pulmonary circulation after induction of anaesthesia. This pulmonary-systemic arterial difference nearly disappeared intraoperatively, but tended to be restored 22 h after the end of operation at an approximately twofold increased level. CONCLUSIONS: No interrelation between ET and the hypothalamic-pituitary-adrenal axis could be established by the ET, ACTH, and cortisol plasma levels. However, the significant correlation between perioperative ET and cortisol lends further support to the hypothesis of ET release by cortisol from vascular smooth-muscle cells. There is a net pulmonary clearance of ET in patients prior to CABG that is lost intra- and early postoperatively, but tends to be restored on the 1st day thereafter at an increased level.

Adrenocorticotropic Hormone↗