Stephan Lehr

Methylene blue improves the hepatopulmonary syndrome.

The hepatopulmonary syndrome is the triad of liver disease, pulmonary gas exchange abnormalities leading to arterial hypoxemia, and widespread pulmonary vascular dilation (1, 2). Both acute and chronic liver diseases have been associated with the hepatopulmonary syndrome. Most commonly, the syndrome presents in patients with chronic liver diseases resulting in cirrhosis. Portal hypertension seems to be the predominant factor related to this syndrome. The hallmark of pulmonary vascular changes in the syndrome are dilated vessels at the precapillary and capillary levels and direct arteriovenous communications (1). This causes right-to-left shunting of blood flow, mismatch between ventilation and perfusion, and diffusion limitation (2). Measuring Pao 2 alone may underestimate the true degree of oxygenation abnormality because of hyperventilation, which is common in patients with cirrhosis. The alveolararterial difference for the partial pressure of oxygen (PAO2 Pao 2) is more accurate because it includes the determination of Paco 2 (which is low as a result of hyperventilation) (2). The prevailing clinical interest in the hepatopulmonary syndrome is based on its relatively high prevalence (it affects 5% to 29% of patients with end-stage liver disease [3]), high mortality rate (41% over an approximate 3-year period, despite clinically stable hepatic dysfunction [1]), and the failure of numerous medical therapies. The mechanism underlying this widespread pulmonary vasodilation is unknown. Over the past few years, increased attention has been focused on nitric oxide (NO), a powerful local vasodilator that contributes to the normally low pulmonary vascular tone. Increased endogenous NO production has been proposed as an important determinant of the hyperdynamic circulation in cirrhosis (4). The free radical NO activates the soluble guanylate cyclase in the vascular smooth muscle, increasing the level of the second messenger cyclic guanosine monophosphate, thereby causing vasorelaxation. In a case report, Pao 2 improved in a patient with the hepatopulmonary syndrome after administration of methylene blue (5), an oxidizing agent that blocks the stimulation of soluble guanylate cyclase by NO. We hypothesized that inhibition of NO-induced vasodilation by methylene blue would improve gas exchange and hemodynamic abnormalities in patients with severe hepatopulmonary syndrome. Methods Patients Our research protocol was approved by the institutional ethics committee of the University of Vienna. Written informed consent was obtained from each patient. We studied seven patients with severe hepatopulmonary syndrome (5 men, 2 women; mean age, 52 years [range, 33 to 64 years]), as defined by a Pao 2 of 60 mm Hg or less. The following strict criteria, recommended by Rodriguez-Roisin and colleagues [2], were used for diagnosis of the hepatopulmonary syndrome: 1) presence of chronic liver disease; 2) absence of intrinsic cardiopulmonary disease; 3) pulmonary gas exchange abnormalities, expressed as an increased PAO2 Pao 2; and 4) a positive contrast-enhanced echocardiogram suggesting intrapulmonary vascular dilation. Measurements and Medication Contrast-enhanced echocardiography was performed by using agitated saline, which creates a stream of microbubbles after intravenous injection (1). Under normal circumstances, these microbubbles, 60 to 90 m in diameter, opacify only the right-heart chambers because they are filtered in the pulmonary capillary bed and do not appear in the left side of the heart. In an intrapulmonary shunt, the microbubbles appear in the left-heart chambers 4 to 6 heart beats after their initial visualization in the right side of the heart. For hemodynamic measurements, a SwanGanz balloon-tipped pulmonary artery catheter (Thermodilution Venous Infusion Port Catheter, 7.5 French, Baxter Healthcare Corp., Irvine, California) was inserted through a central vein (jugular or subclavian). Hemodynamic measurements were performed by using standard techniques while the patient was in the supine position and in the resting state. Cardiac output was recorded in triplicate by thermodilution technique using iced saline, and the average was used for further statistical analysis. An arterial indwelling catheter (Arrow, Reading, Pennsylvania) was inserted in a radial artery for online measurement of arterial blood pressure and repeated blood gas analysis. All measurements were performed in the intensive care unit. Arterial and mixed venous blood gas analysis and hemodynamic measurements were recorded after 30 minutes of rest at baseline and again at 30 minutes and 1, 2, 3, 4, and 5 hours after intravenous administration of methylene blue, 3 mg/kg of body weight injected over a period of 15 minutes. In addition to these scheduled recordings, five patients who remained in the intensive care unit overnight had measurements recorded 10 hours after methylene blue injection. The primary outcome measure was Pao 2 and the secondary outcome variables were Paco 2, PAO2 Pao 2, heart rate, mean systemic arterial pressure, mean pulmonary artery pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac output, systemic vascular resistance, pulmonary vascular resistance, and shunt fraction. Systemic vascular resistance and pulmonary vascular resistance were calculated according to standard formulas. Shunt fraction (VS/VT) was calculated using a standard equation: where CO2, CaO2, and CmvO2 represent the O2 content of ideal, arterial, and mixed venous blood, respectively. The O2 saturation of ideal blood was obtained from the calculated alveolar Po 2 and Pco 2 by using the Kelman subroutine (6). Baseline variables were calculated on the basis of three repeated measurements taken 10 minutes apart. Statistical Analysis A repeated-measures analysis of variance was performed by using proc glm of SAS (SAS Institute, Inc., Cary, North Carolina) to compare the differences between baseline and each of the time points (30 minutes and 1, 2, 3, 4, and 5 hours after intervention). To model the difference over time to baseline, the baseline minus the mean of baseline was included as a covariable. If no significant time effect was found, the average of the repeated differences over time was analyzed by testing the intercept of the model against zero. Because the covariable baseline minus average baseline is used in the model, this test refers to the average difference determined at the mean baseline value (where the covariable is zero). Because of missing data for two patients at 10 hours, a paired t-test to baseline was performed. A P value less than 0.05 was considered statistically significant. Results All patients presented with orthodeoxia (hypoxia worsens upon rising from the supine position to upright posture because of gravitational effects, which leads to increased blood flow to the lower-lung fields) and exertional dyspnea. The participants were nonsmokers who had normal lung function and clear chest radiographs. All patients had advanced cirrhosis (five with ChildPugh class C and two with class B) as established by clinical, biochemical, and histologic findings. The causes of cirrhosis were alcohol related in five patients, hemochromatosis in one patient, and cryptogenic in one patient. At the time of our investigation, no participant had detectable ascites, as assessed by sonography. Various degrees of esophageal varices were present in all patients, including a history of bleeding in three patients. All patients had clubbing of the digits and cutaneous spider nevi, and four patients had more than 50 nevi. All patients had elevated levels of total bilirubin (mean SD, 175 186 mol/L [10.2 10.9 mg/dL]) as well as a prolonged prothrombin time (mean, 36 10 seconds). The mean hemoglobin value was 94 18 g/L, the mean platelet count was 122 61 109 cells/L, and the mean serum creatinine concentration was 108 67 mol/L (1.2 0.76 mg/dL). At baseline, arterial blood gas analysis showed hypoxemia in all patients, with Pao 2 values between 53 and 60 mm Hg and an increased PAO2 Pao 2 (Table). The Paco 2 value was reduced in all patients because of hyperventilation (mean, 34 2.7 mm Hg [range, 29 to 37 mm Hg]). Shunt fraction was greatly elevated (41% 3.1%). At baseline, all patients showed hyperdynamic circulation with diminished pulmonary vascular resistance (58 23 dyne/sec cm 5) and systemic vascular resistance (527 144 dyne/sec cm 5), and elevated cardiac output (10.6 2.2 L/min). The effect of methylene blue administration on gas exchange and hemodynamic variables is shown in the Table. The one variable with a significant time effect was Paco 2. No other significant time effects were observed; for these variables, the P value refers to the test of the average repeated differences against zero. After methylene blue infusion, Pao 2 showed a significant average increase over time compared with baseline (P=0.006), from 58 2.5 mm Hg at baseline to 74 11.5 mm Hg 5 hours after methylene blue administration. Consistent with the increase in Pao 2, PAO2 Pao 2 decreased significantly from 49 3.3 mm Hg at baseline to 30 10.4 mm Hg at the 5-hour measurement (P=0.003). The Paco 2 value increased slightly (from 34 2.7 mm Hg at baseline to 37 4.5 mm Hg after 5 hours; P=0.007 for the time effect). Shunt fraction decreased significantly (P <0.001); the lowest mean value occurred at the 5-hour measurement (25% 4.5%). Table. Gas Exchange and Hemodynamic Responses to Short-Term Infusion of Methylene Blue In addition, mean pulmonary artery pressure increased significantly (from 20 5.2 mm Hg to 23 3.6 mm Hg; P=0.028), as did pulmonary vascular resistance (from 58 23 dyne/sec cm 5 to 115 56 dyne/sec cm 5; P=0.012). Mean systemic arterial pressure increased, but the difference was not statistically significant. Central venous pressure and pulmonary capillary wedge pressure did not change. Cardiac output decreased (from 10.6 2.2 L/min at baseline to 8.6 2.7 L/min

Contribution of nicotine to acute endothelial dysfunction in long-term smokers

OBJECTIVES The aim of this study was to determine whether nicotine, a constituent of cigarette smoke, contributes to acute endothelial dysfunction after smoking one cigarette. BACKGROUND Animal studies suggest that nicotine might cause an impairment of endothelium-dependent vasodilation via an increase in oxidative stress. METHODS Sixteen healthy smokers were entered into a randomized, observer-blinded crossover study comparing the effects of nicotine nasal spray (1-mg nicotine) and cigarette smoke (1-mg nicotine, 12 mg tar) on vascular reactivity in the brachial artery. Using high-resolution ultrasound, flow-mediated dilation (FMD) and endothelium-independent, nitroglycerin-induced dilation were assessed at baseline and 20 min after the administration of nicotine (spray or cigarette). RESULTS In response to similar increases in nicotine serum levels, FMD values declined from 10.2 +/- 4.4% to 6.7 +/- 4.0% after the spray (mean difference: -3.6 +/- 2.0%, 95% confidence interval: -4.6; -2.5, p < 0.0001) and from 9.4 +/- 3.8% to 4.3 +/- 2.8% after the cigarette (-5.1 +/- 2.6%, -6.5; -3.7, p < 0.0001). Nitroglycerin-induced dilation remained similar within both periods. Performing a period effect analysis of variance, a significant influence on FMD was found for the mode of administration (p = 0.017) and the baseline value (p = 0.021). The effect on FMD was more pronounced after the cigarette than after the spray (estimated average effect difference: 1.9% FMD). Oxidation parameters did not increase significantly after nicotine spray or tobacco exposure. CONCLUSIONS These results demonstrate that nicotine alone causes acute endothelial dysfunction, although to a lesser extent than smoking a cigarette of the same nicotine yield. However, the precise mechanisms by which nicotine leads to this altered vascular reactivity remain unclear.

Effects of vitamin E on chronic and acute endothelial dysfunction in smokers

OBJECTIVES The aims of this study were to determine whether chronic or acute impairment of flow mediated vasodilation (FMD) in the brachial artery of smokers can be restored or preserved by the antioxidant vitamin E. BACKGROUND Transient impairment of endothelial function after heavy cigarette smoking and chronic endothelial dysfunction in smokers result at least in part from increased oxidative stress. METHODS We studied 22 healthy male smokers (mean +/- SD, 23 +/- 9 cigarettes per day) randomly assigned to receive either 600 IU vitamin E per day (n = 11, age 28 +/- 6 years) or placebo (n = 11, age 27 +/- 6 years) for four weeks and 11 age-matched healthy male nonsmokers. Flow mediated vasodilation and endothelium-independent, nitroglycerin-induced dilation were assessed in the brachial artery using high resolution ultrasound (7.5 MHz) at baseline and after therapy. Subjects stopped smoking 2 h before the ultrasound examinations. At the end of the treatment period, a third scan was obtained 20 min after smoking a cigarette (0.6 mg nicotine, 7 mg tar) to estimate transient impairment of FMD. RESULTS Flow mediated vasodilation at baseline was abnormal in the vitamin E (5.3 +/- 3.8, p < 0.01) and in the placebo group (6.4 +/- 3.5, p < 0.05) compared with nonsmoking controls (11.6 +/- 4.7). Using a two-way repeated measures analysis of variance (ANOVA) to examine the effects of vitamin E on FMD, we found no effect for the grouping factor (p = 0.5834) in the ANOVA over time but a highly significant difference with respect to time (p = 0.0065). The interaction of the time factor and the grouping factor also proved to be significant (p = 0.0318). Flow mediated vasodilation values remained similar after treatment for four weeks in both groups but declined faster after smoking a cigarette in subjects taking placebo compared with those receiving vitamin E (p values from successive differences for the time/group factor: 0.0001/0.0017). The transient attenuation of FMD (calculated as the percent change in FMD) was related to the improvement of the antioxidant status, estimated as percent changes in thiobarbituric acid-reactive substances (r = -0.67, p = 0.0024). Nitroglycerin-induced dilation did not differ between study groups at baseline or after therapy. CONCLUSIONS These results demonstrate that oral supplementation of vitamin E can attenuate transient impairment of endothelial function after heavy smoking due to an improvement of the oxidative status but cannot restore chronic endothelial dysfunction within four weeks in healthy male smokers.

The sunburn pain model: the stability of primary and secondary hyperalgesia over 10 hours in a crossover setting.

It was our aim to study the within-day stability and between-day repeatability of ultraviolet B (UVB) light-induced primary and secondary hyperalgesia over 10 h. Twenty hours after UVB irradiation of a skin spot (r = 2.5 cm) on the upper leg of 8 healthy volunteers the areas of secondary hyperalgesia to pinprick and pain tolerance thresholds to heat (HPTT) and electrical stimuli (5 and 250 Hz, electrical pain tolerance thresholds [EPTT]) were assessed. Measurements were repeated for 10 h at 2-h intervals and in 2 different sessions. Large areas of secondary hyperalgesia to pin prick were observed (5995 mm2; sd, 1645). Primary hyperalgesia was evidenced by significant decreases of HPTT (mean difference, 6.5°C; 95% confidence interval, 6.1–6.8; P < 0.001) and EPTT at 250 Hz (mean difference, 0.45 mA; 95% confidence interval, 0.13–0.78; P < 0.05) compared to normal skin. There was no trend within one session of either primary (P = 0.14 for HPTT) or secondary hyperalgesia (P = 0.95) and no difference between the two sessions (primary hyperalgesia, P = 0.28; secondary hyperalgesia, P = 0.07). The sunburn pain model provides a long time course of stable hyperalgesia with a high within-day stability and between-day repeatability for primary and secondary hyperalgesia

A Lack of Antinociceptive or Antiinflammatory Effect of Botulinum Toxin A in an Inflammatory Human Pain Model

Several in vitro and in vivo investigations have shown that botulinum toxin A (BoNT/A) can inhibit the release of substance P and excitatory amino acids. Recently, a marked antinociceptive effect of BoNT/A and inhibition of glutamate release was observed in an animal pain model with inflammatory sensitization. In the present study, we tested the antiinflammatory and antihyperalgetic effect of BoNT/A in a well-characterized human inflammatory pain model. Using a randomized, double-blind, paired study design, we compared the effects of 100 mouse units of BoNT/A versus pure saline. Thermal and mechanical pain testings and superficial skin blood flow measurements were performed at baseline, at 48 h (in normal skin), and at 72 h (in inflamed skin) thereafter. Ultraviolet B irradiation resulted in a local inflammation with significant primary and secondary hyperalgesia. However, despite the evidence of efficacy on sudomotor function, BoNT/A had no effect on pain measures in either normal or inflamed skin. Signs of inflammation and primary and secondary hyperalgesia were found to be unaffected by BoNT. We have confirmed that BoNT/A has no direct effect on acute, noninflammatory pain. Furthermore, despite highly promising data from animal research, we have not observed antiinflammatory or antinociceptive effects of BoNT/A in human inflammatory pain.

The formation of platelet–leukocyte aggregates varies during the menstrual cycle

Platelet–leukocyte aggregates are considered to play a significant role in blood coagulation and inflammatory processes. We hypothesized that hormonal changes during the menstrual cycle affect the formation of heterotypic aggregates and therefore may constitute cycle-dependent variations of the susceptibility for thromboembolic events and inflammatory disease. We therefore measured platelet–leukocyte interaction by the determination of platelet–leukocyte aggregates (PLA), platelet P-Selectin expression, and platelet fibrinogen receptor activation by PAC-1 binding in 20 healthy women during their menstrual cycle by flow cytometry. The number of platelet–granulocyte aggregates (PGA) and platelet–monocyte aggregates (PMA) was higher at ovulation compared to any other time-point of the menstrual cycle (p = 0.005, p = 0.022, respectively). Likewise, P-Selectin expression peaked on day 14 (p = 0.040). The course of PLA formation during the menstrual cycle followed the course of estrogen levels, strongly suggesting direct effects of estrogen on platelet–leukocyte interaction. The susceptibility to form platelet–leukocyte aggregates that are inducible in vitro by a suboptimal concentration of thrombin receptor activating peptide-6 decreased slightly during the transition from day 1 to 14 (p = 0.040). These data indicate that platelet function varies during particular phases of the normal menstrual cycle.

Do monthly or seasonal variations exist in suicides in a high-risk setting?

An unequal distribution of suicides over months and seasons has been a consistent finding in epidemiological surveys on suicide. Jails and prisons are a high-risk setting for suicide all over the world. The high prevalence of both outward and self-directed violence in prison populations indicates dysfunctional central serotonin (5-HT) neurotransmission and, therefore, could account for an unequal distribution of suicides over months and seasons due to underlying bioclimatic factors. Within a total survey of suicides in the Austrian penitentiary system, the weekly, monthly and seasonal distribution of custodial suicides between 1947 and 1999 was studied. After an explorative comparison of suicide distribution over weekdays, months and seasons of the year by chi2-tests, a harmonic Poisson regression model was performed to detect seasonality of suicides. No unequal distribution of suicides was evident over the 53-year period. A limitation of this study was its sample size of 412, a low number compared with population-based samples, where a spring suicide peak was consistently found. An explanation for lacking seasonality could be that bioclimatic factors are less relevant in urban, industrialized areas, where jails and prisons usually are located. One of the core characteristics of penal institutions is the limited possibility for communication and social interaction. This social isolation is independent of seasonal changes. If the individuals possibilities for social interactions are limited, the influence of seasonal changes in social activities may be less relevant. This could explain the absence of seasonal changes in custodial suicide incidence.

Intravenous magnesium sulfate for bronchial hyperreactivity: A randomized, controlled, double‐blind study

Magnesium has been shown to be helpful in the treatment of acute exacerbations of asthma. Conflicting data exist concerning the effect of magnesium on bronchial hyperreactivity.

The FcγRIIa polymorphism R/H131, autoantibodies against the platelet receptors GPIbα and FcγRIIa and a risk for thromboembolism in lupus anticoagulant patients

There is a clear propensity of individuals with lupus anticoagulant (LA) for thromboembolic disease (TE). Yet, it is not clear how individuals at risk for TE can be differentiated from those who are not.The FcγRIIa receptor is the only Fc receptor expressed by platelets.As platelets can be activated via this receptor, we have compared gene frequencies of the FcγRIIa polymorphism R/H131 in 46 and 27 patients with (LA/TE+) and without TE (LA/TE-), respectively, in an exploratory study. Furthermore, we investigated the presence of autoantibodies against FcγRIIa and/or GPIbα , which is in close proximity to the FcγRIIa and interacts with it functionally, and a possible linkage of antibody formation to HLA class II alleles.The FcγRIIa-R/R131 genotype was significantly less frequent in patients with LA compared to controls (p

The adaptive immune system and long-term outcome in patients with stable coronary disease Predictive value of routine laboratory measurements

Components of the adaptive immune system, in particular lymphocytes and immunoglobulin, play a major role in advanced atherosclerotic lesions. We sought to determine whether routine, measurements of the relative number of circulating lymphocytes (%L) and gamma-globulin (%G) reflecting immunoglobulin are related to event-free survival in patients with stable coronary artery disease (CAD). We prospectively studied the combined endpoint all-cause mortality, myocardial infarction and coronary revascularization procedures in 141 patients after successful percutaneous coronary intervention during a median follow-up time of 13.2 years. Using Cox regression, we found a significant influence of %L on event-free survival (P=0.007) with a relative risk of 2.21 comparing third to first tertile. Subjects with higher %G values likewise had a shorter event-free survival (P=0.008) with a relative risk of 1.67 comparing third to first tertile. The predictive value of %L and %G remained significant after adjustment for demographic data, cardiovascular risk factors, extent of CAD and other inflammatory markers. We conclude that the fraction of gamma-globulin and in particular the relative lymphocyte cell count may serve as readily available and reliable prognostic tools for the long-term outcome in patients with stable CAD.