Dopexamine Reverses the Vasopressin-Associated Impairment in Tissue Oxygen Supply but Decreases Systemic Blood Pressure in Ovine Endotoxemia

Therapeutic regimens of endotoxaemia in sheep

Endotoxaemia is an inflammatory condition which happens due to the presence of outer cell wall layer of Gram-negative bacteria in blood circulation, containing lipopolysaccharide commonly known as endotoxin. This condition causes high mortality in affected animals and sheep are highly susceptible in this regard. Several researchers have emphasised the therapeutic regimens of endotoxaemia and its sequels in sheep. Furthermore, sheep are among the most commonly used animal species in experimental studies on endotoxaemia, and for the past five decades, ovine models have been employed to evaluate different aspects of endotoxaemia. Currently, there are several studies on experimentally induced endotoxaemia in sheep, and information regarding novel therapeutic protocols in this species contributes to better understanding and treating the condition. This review aims to specifically introduce various treatment methods of endotoxaemia in sheep.

The value of assessment tests in patients with acute exacerbation of chronic obstructive pulmonary disease

The aim of our study was to investigate the chronic obstructive pulmonary disease (COPD) assessment test (CAT), serum copeptin, procalcitonin and C-reactive protein (CRP) levels as potential predictive factors for recurrence of acute exacerbation and all-cause mortality in 6 months of COPD inpatients. One hundred fifty-nine patients who met the inclusion criteria were enrolled and followed up for 6 months. The CAT scores, serum copeptin, procalcitonin and CRP levels were measured on admission and 14 days and 3 months later in all patients. The primary endpoint was recurrence of acute exacerbation in 6 months. The secondary endpoint was all-cause mortality after 6 months. The CAT scores, serum copeptin, procalcitonin and CRP levels were significantly elevated on admission and stabilized at 14 days (P < 0.01). In a univariate logistic regression analysis, CAT scores (odds ratio [OR] = 1.10), forced expiratory volume in 1 second % (OR = 1.01), serum copeptin (OR = 1.32) and CRP levels (OR = 1.01) were significantly related to recurrence of acute exacerbation in 6 months (P < 0.05). In a multivariate logistic regression model, increasing CAT scores (OR = 1.10) and serum copeptin levels (OR = 1.29) were still associated with an increased odds of exacerbation (P < 0.05). In a univariate logistic regression analysis, increasing CAT scores (OR = 1.19), forced expiratory volume in 1 second % (OR = 1.05), serum copeptin levels (OR = 1.44) and hospitalization in the previous years (OR = 1.24) were significant determinants of death over a follow-up period of 6 months (P < 0.05). But only serum copeptin (OR = 1.53) and CAT scores (OR = 1.37) were associated with mortality in multivariate logistic regression analysis. Hence, high CAT scores and serum copeptin levels link with recurrence of acute exacerbation and all-cause mortality during 6 months in patients with acute exacerbation of COPD.

Selective V(1a) agonism attenuates vascular dysfunction and fluid accumulation in ovine severe sepsis

Vasopressin analogs are used as a supplement to norepinephrine in septic shock. The isolated effects of vasopressin agonists on sepsis-induced vascular dysfunction, however, remain controversial. Because V(2)-receptor stimulation induces vasodilation and procoagulant effects, a higher V(1a)- versus V(2)-receptor selectivity might be advantageous. We therefore hypothesized that a sole, titrated infusion of the selective V(1a)-agonist Phe(2)-Orn(8)-Vasotocin (POV) is more effective than the mixed V(1a)-/V(2)-agonist AVP for the treatment of vascular and cardiopulmonary dysfunction in methicillin resistant staphylococcus aureus pneumonia-induced, ovine sepsis. After the onset of hemodynamic instability, awake, chronically instrumented, mechanically ventilated, and fluid resuscitated sheep were randomly assigned to receive continuous infusions of either POV, AVP, or saline solution (control; each n = 6). AVP and POV were titrated to maintain mean arterial pressure above baseline - 10 mmHg. When compared with that of control animals, AVP and POV reduced neutrophil migration (myeloperoxidase activity, alveolar neutrophils) and plasma levels of nitric oxide, resulting in higher mean arterial pressures and a reduced vascular leakage (net fluid balance, chest and abdominal fluid, pulmonary bloodless wet-to-dry-weight ratio, alveolar and septal edema). Notably, POV stabilized hemodynamics at lower doses than AVP. In addition, POV, but not AVP, reduced myocardial and pulmonary tissue concentrations of 3-nitrotyrosine, VEGF, and angiopoietin-2, thereby leading to an abolishment of cumulative fluid accumulation (POV, 9 ± 15 ml/kg vs. AVP, 110 ± 13 ml/kg vs. control, 213 ± 16 ml/kg; P < 0.001 each) and an attenuated cardiopulmonary dysfunction (left ventricular stroke work index, PaO(2)-to-FiO(2) ratio) versus control animals. Highly selective V(1a)-agonism appears to be superior to unselective vasopressin analogs for the treatment of sepsis-induced vascular dysfunction.

Copeptin in the assessment of acute lung injury and cardiogenic pulmonary edema

BACKGROUNDS

Copeptin has been studied as an excellent predictor of outcome in a variety of diseases, its value is even superior to that of B-type natriuretic peptide (BNP) in heart failure, but little is known about its characteristics in acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). We sought to assess the diagnostic and prognostic value of copeptin together with N-terminal pro-BNP (NT-proBNP) in patients with ARDS/ALI or cardiogenic pulmonary edema (CPE).

METHODS

Measurement of copeptin and NT-proBNP levels in plasma from 121 consecutive patients with either ARDS/ALI or CPE enrolled in a prospective single center study.

RESULTS

In a derivation cohort of 87 patients with ARDS/ALI and 34 patients with CPE, a copeptin threshold of >40.11 pmol/L provided a specificity of 88.2% and a sensitivity of 60.9% for the diagnosis of ARDS/ALI, a NT-proBNP cut point of <2813 pg/ml had a specificity of 79.4% and sensitivity of 65.5% for it. Multivariate Cox regression analysis showed that copeptin was the strongest predictor for mortality in patients with ARDS/ALI [hazard ratio (HR) = 4.72, P < 0.001] and CPE (HR = 3.52, P = 0.019), the association between increasing copeptin and death was statistically significant in patients with ARDS/ALI (HR = 2.64, P = 0.035) and patients with CPE (HR = 1.62, P = 0.029).

CONCLUSION

Copeptin of >40.11 pmol/L had a high specificity for the diagnosis of ARDS/ALI in patients presenting with ARDS/ALI or CPE. Compared to NT-proBNP, copeptin was a stronger prognostic marker for short-term mortality.

Effects of two different dosing regimens of terlipressin on organ functions in ovine endotoxemia

OBJECTIVE AND DESIGN

To test the hypothesis that a continuous infusion of the vasopressin analog terlipressin is associated with less organ dysfunction as compared to intermittent bolus infusion in an ovine sepsis model.

SUBJECTS

Twenty-seven adult female sheep.

TREATMENT

All sheep were subjected to a Salmonella typhosa endotoxin infusion (10 ng/kg/min). After 16 h of endotoxemia, the surviving animals (n = 24) were randomized to (1) an untreated control group, (2) a continuous terlipressin group (2 mg/24 h), or (3) a terlipressin bolus group (1 mg/6 h).

METHODS

Hemodynamic variables were measured and blood was withdrawn at specific time points for the assessment of organ functions.

RESULTS

Continuous terlipressin infusion was associated with improved surrogate parameters of myocardial, renal, and hepatic function as compared with terlipressin bolus infusion. Reduced vascular hyperpermeability was evidenced by an attenuated decrease in plasma protein concentrations in sheep treated with continuous terlipressin infusion as compared to bolus injection or no treatment.

CONCLUSIONS

Continuous infusion of low-dose terlipressin preserved several surrogate parameters of organ function better than intermittent bolus injections in sheep with systemic inflammation.

Copeptin and risk stratification in patients with acute dyspnea

Introduction

The identification of patients at highest risk for adverse outcome who are presenting with acute dyspnea to the emergency department remains a challenge. This study investigates the prognostic value of Copeptin, the C-terminal part of the vasopressin prohormone alone and combined to N-terminal pro B-type natriuretic peptide (NT-proBNP) in patients with acute dyspnea.

Methods

We conducted a prospective, observational cohort study in the emergency department of a university hospital and enrolled 287 patients with acute dyspnea.

Results

Copeptin levels were elevated in non-survivors (n = 29) compared to survivors at 30 days (108 pmol/l, interquartile range (IQR) 37 to 197 pmol/l) vs. 18 pmol/l, IQR 7 to 43 pmol/l; P < 0.0001). The areas under the receiver operating characteristic curve (AUC) to predict 30-day mortality were 0.83 (95% confidence interval (CI) 0.76 to 0.90), 0.76 (95% CI 0.67 to 0.84) and 0.63 (95% CI 0.53 to 0.74) for Copeptin, NT-proBNP and BNP, respectively (Copeptin vs. NTproBNP P = 0.21; Copeptin vs. BNP P = 0.002). When adjusted for common cardiovascular risk factors and NT-proBNP, Copeptin was the strongest independent predictor for short-term mortality in all patients (HR 3.88 (1.94 to 7.77); P < 0.001) and especially in patients with acute decompensated heart failure (ADHF) (HR 5.99 (2.55 to 14.07); P < 0.0001). With the inclusion of Copeptin to the adjusted model including NTproBNP, the net reclassification improvement (NRI) was 0.37 (P < 0.001). An additional 30% of those who experienced events were reclassified as high risk, and an additional 26% without events were reclassified as low risk.

Conclusions

Copeptin is a new promising prognostic marker for short-term mortality independently and additive to natriuretic peptide levels in patients with acute dyspnea.

C-reactive protein and copeptin: prognostic predictors in chronic obstructive pulmonary disease exacerbations

PURPOSE OF REVIEW

Acute exacerbation of chronic obstructive pulmonary disease (COPD) is a natural event in the course of COPD and remains a major cause of morbidity and mortality associated with this disease. Clinical criteria that define an acute exacerbation are subjective and open for debate. Identifying biomarkers that would be easily measured and followed in patients with acute exacerbation of COPD seems to be highly attractive. The aim of this review is to assess the role of biomarkers, C-reactive protein (CRP) and copeptin, as prognostic predictors in COPD exacerbations.

RECENT FINDINGS

Many pulmonary biomarkers have been extensively studied in the recent years. CRP and copeptin have gained particular interest. Recent data suggest that CRP is elevated during an acute exacerbation of COPD but CRP alone is neither sensitive nor specific in predicting clinical severity or outcome. Copeptin increases during acute exacerbation of COPD and may correlate with disease severity.

SUMMARY

Further studies are needed to determine the role of CRP and copeptin as biomarkers that aid in diagnosis and clinical outcome in acute exacerbation of COPD.

Neuronal nitric oxide synthase inhibition attenuates cardiopulmonary dysfunctions after combined burn and smoke inhalation injury in sheep

OBJECTIVE

We hypothesized that nitric oxide derived from the neuronal nitric oxide synthase (NOS) is responsible for much of the injury resulting from skin burn and smoke inhalation. Therefore, we aimed to examine the effects of selective neuronal NOS inhibition on cardiopulmonary functions and cellular injury in sheep with acute respiratory distress syndrome secondary to combined burn and smoke inhalation injury.

DESIGN

Prospective, randomized, controlled laboratory experiment.

SETTING

Investigational intensive care unit.

SUBJECTS

A total of 22 chronically instrumented adult ewes.

INTERVENTIONS

Sheep were randomly assigned to either healthy controls (sham), injured controls (40% third-degree flame burn; 48 breaths of cotton smoke), or an injury group treated with the specific neuronal NOS inhibitor 7-nitroindazole (1 mg x kg(-1) x hr(-1)) from 1 hr postinjury to the end of the 48-hr study period. Hypoxic pulmonary vasoconstriction was assessed as decrease in left pulmonary blood flow in response to single-lung hypoxic challenges (100% nitrogen) at baseline, 24 hrs, and 48 hrs.

MEASUREMENTS AND MAIN RESULTS

The combination injury contributed to a approximately 90% loss of hypoxic pulmonary vasoconstriction and was associated with significant pulmonary shunting and death of one animal. The increase in nitrate/nitrite plasma levels in injured controls (12 hrs: 17 +/- 2 vs. 6 +/- 1 microM in sham animals; p < .001) was linked to increases in inducible NOS messenger RNA and 3-nitrotyrosine formation in lung tissue (48 hrs: 22 +/- 1 vs. 0.8 +/- 0.3 nM in sham animals; p < .001). 7-Nitroindazole treatment prevented the injury-associated changes in inducible NOS messenger RNA, nitrate/nitrite, and 3-nitrotyrosine, thereby attenuating the loss of hypoxic pulmonary vasoconstriction and improving gas exchange. In addition, 7-nitroindazole decreased lung tissue concentrations of hemoxygenase-1 and ameliorated myocardial depression, airway obstruction, pulmonary edema, ventilatory pressures, and histopathologic changes seen in injured controls.

CONCLUSIONS

The present study provides evidence that neuronal NOS-derived nitric oxide plays a pivotal role in the pathogenesis of acute respiratory distress syndrome resulting from combined burn and smoke inhalation injury.

Employing dobutamine as a useful agent to reverse the terlipressin-linked impairments in cardiopulmonary hemodynamics and global oxygen transport in healthy and endotoxemic sheep

Although arginine vasopressin and terlipressin have been identified as useful nonadrenergic agents to increase systemic blood pressure in catchecholamine-resistant septic shock, the impairments in cardiac index (CI) and global oxygen transport may limit their clinical applicability. The present study was designed as a prospective controlled laboratory experiment to investigate the effects of dobutamine as an adjunct to terlipressin infusion on cardiopulmonary hemodynamics and global oxygen transport in healthy and endotoxemic sheep. Nine adult ewes were instrumented for chronic study using an established protocol. After a baseline measurement in the healthy state had been performed, 1 mg terlipressin was given as bolus infusion. Thirty minutes later, dobutamine was continuously infused at incremental doses (2 and 5 microg x kg(1) x min(1), each for 1 h). After 24 h of recovery, a hypotensive-hyperdynamic circulation was induced and maintained by a continuous infusion of Salmonella typhosa endotoxin (10 ng x kg(1) x min(1)). After 16 h of endotoxemia, the six surviving sheep received terlipressin and dobutamine according to the same protocol that was used in healthy sheep. Compared with baseline, terlipressin infusion was associated with a significant increase in MAP that, however, occurred at the expense of a compromised CI, oxygen delivery index (DO(2)I), and mixed venous oxygen saturation (SvO(2), each P < 0.05). Dobutamine infusion was followed by a dose-dependent increase in CI, DO(2)I, and SvO(2) in both health and endotoxemia (each P < 0.05). Although the higher dosage of dobutamine exerted favorable effects, such as a decrease in pulmonary vascular resistance index (P < 0.05), the associated onset of tachycardia (P < 0.05) and arterial hypotension (P < 0.05) may limit its therapeutic use under septic conditions. This study provides evidence that dobutamine in a dosage of 2 microg x kg(1) x min(1) is useful to reverse the terlipressin-linked depressions in CI, DO(2)I and SvO(2) in ovine endotoxemia without obvious side effects.

Effects of short-term simultaneous infusion of dobutamine and terlipressin in patients with septic shock: the DOBUPRESS study

BACKGROUND

Terlipressin bolus infusion may reduce cardiac output and global oxygen supply. The present study was designed to determine whether dobutamine may counterbalance the terlipressin-induced depression in mixed-venous oxygen saturation (Svo) in patients with catecholamine-dependent septic shock.

METHODS

Prospective, randomized, controlled study performed in a university hospital intensive care unit. Septic shock patients requiring a continuous infusion of norepinephrine (0.9 microg kg(-1) min(-1)) to maintain mean arterial pressure (MAP) at 70 (sd 5) mm Hg were randomly allocated to be treated either with (i) sole norepinephrine infusion (control, n=20), (ii) a single dose of terlipressin 1 mg (n=19), or (iii) a single dose of terlipressin 1 mg followed by dobutamine infusion titrated to reverse the anticipated reduction in Svo2 (n=20). Systemic, pulmonary, and regional haemodynamic variables were obtained at baseline and after 2 and 4 h. Laboratory surrogate markers of organ (dys)function were tested at baseline and after 12 and 24 h.

RESULTS

Terlipressin (with and without dobutamine) infusion preserved MAP at 70 (5) mm Hg, while allowing to reduce norepinephrine requirements to 0.17 (0.2) and 0.2 (0.2) microg kg(-1) min(-1), respectively [vs1.4 (0.3) microg kg(-1) min(-1) in controls at 4 h; each P<0.001]. The terlipressin-linked decrease in Svo2 was reversed by dobutamine at a mean dose of 20 (8) microg kg(-1) min(-1) [Svo2 at 4 h: 59 (11)% vs 69 (12)%, P=0.028].

CONCLUSIONS

In human catecholamine-dependent septic shock, terlipressin (with and without concomitant dobutamine infusion) increases MAP and markedly reduces norepinephrine requirements. Although no adverse events were noticed in the present study, potential benefits of increasing Svo2 after terlipressin bolus infusion need to be weighted against the risk of cardiovascular complications resulting from high-dose dobutamine.

Continuous versus bolus infusion of terlipressin in ovine endotoxemia

In patients with sepsis, hemodynamic support is often complicated by a tachyphylaxis against conventional vasopressor agents. Bolus infusion of terlipressin, a vasopressin analog, has been reported to increase mean arterial pressure in patients with catecholamine-resistant septic shock. However, bolus infusion of terlipressin may be associated with severe side effects, including pulmonary vasoconstriction and impairment of oxygen delivery. We hypothesized that continuous low-dose infusion of terlipressin may reverse sepsis-related systemic arterial hypotension with reduced side effects as compared with the traditional concept of bolus administration. Twenty-seven adult sheep were instrumented for chronic study. After a baseline measurement, Salmonella typhosa endotoxin (10 ng.kg-1.min-1) was continuously administered for the next 40 h. After 16 h of endotoxemia, the surviving sheep (n = 24) were randomly assigned to be treated with either a continuous infusion of terlipressin (2 mg for 24 h), bolus injections of terlipressin (1 mg every 6 h), or placebo (normal saline; each n = 8). Continuous infusion of terlipressin permanently reversed endotoxin-induced systemic arterial hypotension (P < 0.001) and improved left ventricular stroke work index in all sheep (P < 0.05). Intermittent bolus injections of terlipressin were linked to decreases in heart rate and cardiac index and increases in pulmonary vascular resistance index (each, P < 0.001). These unwanted side effects were prevented by continuous low-dose infusion of the drug. In conclusion, continuous infusion of terlipressin stabilized hemodynamics and improved myocardial performance in endotoxemic ewes without obvious side effects. Continuous low-dose terlipressin infusion may represent a useful alternative treatment of arterial hypotension related to sepsis and systemic inflammatory response syndrome.

Hemodynamic effects of titrated norepinephrine in healthy versus endotoxemic sheep

In patients with sepsis and systemic inflammatory response syndrome, hemodynamic support is often complicated by a vascular hyporesponsiveness to exogenously administered norepinephrine. Although norepinephrine tachyphylaxis represents a significant clinical problem, the relationship between norepinephrine dosages and mean arterial pressure (MAP) in the presence of systemic inflammation is still not fully understood. This study was, therefore, designed as a prospective, controlled laboratory trial to elucidate the hemodynamic response to incremental norepinephrine doses in healthy and endotoxemic sheep. ANOVA demonstrated that a significantly higher mean infusion rate of norepinephrine was needed to increase MAP by 20 mmHg in endotoxemic versus healthy control sheep (P = 0.007). Whereas the goal-MAP was reached in 100% of healthy controls, it was achieved in only 80% during endotoxemia. Cardiac index increased significantly in healthy, but not in endotoxemic, sheep. Our findings confirm the presence of vascular hyporesponsiveness to norepinephrine in endotoxemia. In addition, this study demonstrates that the presence of systemic inflammation leads to an early hyporesponsiveness against norepinephrine which was caused by a drug-independent mechanism rather than a tachyphylaxis due to long-term administration of norepinephrine.

Continuously infused glipizide reverses the hyperdynamic circulation in ovine endotoxemia

In advanced sepsis, hemodynamic support is often complicated by a tachyphylaxis against exogenous catecholamines. Although activation of adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels plays a pivotal role in the pathogenesis of hyperdynamic vasodilatory shock, previous studies demonstrated only a transient increase in mean arterial pressure (MAP) after bolus administration of K(ATP) channel inhibitors. We hypothesized that a continuous infusion of the sulfonylurea glipizide, a K(ATP) channel inhibitor, may reverse cardiovascular dysfunctions in sepsis permanently. Eighteen adult sheep were instrumented for chronic study. After a baseline measurement in healthy ewes, endotoxin (Salmonella typhosa, 10 ng kg(-1) min(-1)) was continuously infused for 19 h. After 16 h of endotoxemia, the surviving sheep (n = 14) were randomly assigned to be treated with either glipizide (5 mg/kg, followed by a continuous infusion of 8 mg kg(-1) h(-1)) or placebo (normal saline; each n = 7). Measurements of cardiopulmonary hemodynamics, global oxygen transport, acid-base status, and urine output were performed in the healthy state, after 16 h of endotoxemia, and during 3 h of glipizide infusion. Continuous infusion of glipizide reversed the endotoxin-induced hyperdynamic circulation, as indicated by significant increases in MAP and systemic vascular resistance index, as well as decreases in cardiac index and heart rate (P < 0.001 each). In addition, glipizide increased urine output as compared with untreated controls (P < 0.001). The anticipated decrease in glucose plasma levels was prevented by infusion of glucose 5%. From these results, we conclude that continuous glipizide infusion may represent a useful therapeutic option in the treatment of arterial hypotension related to sepsis and systemic inflammatory response syndrome.

Methylprednisolone reverses vasopressin hyporesponsiveness in ovine endotoxemia

Tachyphylaxis against catecholamines often complicates hemodynamic support in patients with septic shock. Recent experimental and clinical research suggests that the hemodynamic response to exogenous arginine vasopressin (AVP) infusion may also be blunted. The purpose of the present study was therefore to clarify whether the efficacy of a continuous AVP infusion (0.04 U x min(-1)) decreases over time in ovine endotoxemia. An additional objective was to determine whether the anticipated hyporesponsiveness can be counteracted by corticosteroids. Fourteen adult ewes (37 +/- 1 kg) were instrumented for chronic hemodynamic monitoring. All ewes received a continuous endotoxin infusion that contributed to a hypotensive-hyperdynamic circulation. After 16 h of endotoxemia, the sheep were randomized to receive either AVP (0.04 U x min(-1)) or the vehicle (normal saline; n = 7 each). After 6 h of AVP or placebo infusion, respectively, methylprednisolone (30 mg x kg(-1)) was injected. Arginine vasopressin infusion increased mean arterial pressure and systemic vascular resistance index at the expense of a reduced cardiac index (P < 0.05 each). Supraphysiologic AVP plasma levels in the treatment group (298 +/- 15 pg x mL(-1)) were associated with increased surrogate parameters of liver, mesenterial, and myocardial dysfunction. After 6 h of continuous AVP infusion, the vasopressor effect was significantly reduced. Interestingly, a bolus infusion of methylprednisolone (30 mg x kg(-1)) reestablished mean arterial pressure by increasing both cardiac index and systemic vascular resistance index. The present study demonstrates that in endotoxemia, (a) the vasopressor effect of AVP infusion may be reduced, (b) corticosteroids may potentially be useful to increase the efficacy of AVP infusion, and (c) even moderate AVP doses may potentially impair myocardial and hepatic function.

Copeptin, C-Reactive Protein, and Procalcitonin as Prognostic Biomarkers in Acute Exacerbation of COPD

BACKGROUND

A novel approach to estimate the severity of COPD exacerbation and predict its outcome is the use of biomarkers. We assessed circulating levels of copeptin, the precursor of vasopressin, C-reactive protein (CRP), and procalcitonin as potential prognostic parameters for in-hospital and long-term outcomes in patients with acute exacerbation of COPD (AECOPD) requiring hospitalization.

METHODS

Data of 167 patients (mean age, 70 years; mean FEV(1), 39.9 +/- 16.9 of predicted [+/- SD]) presenting to the emergency department due to AECOPD were analyzed. Patients were evaluated based on clinical, laboratory, and lung function parameters on hospital admission, at 14 days, and at 6 months.

RESULTS

Plasma levels of all three biomarkers were elevated during the acute exacerbation (p < 0.001), but levels at 14 days and 6 months were similar (p = not significant). CRP was significantly higher in patients presenting with Anthonisen type I exacerbation (p = 0.003). In contrast to CRP and procalcitonin, copeptin on hospital admission was associated with a prolonged hospital stay (p = 0.002) and long-term clinical failure (p < 0.0001). Only copeptin was predictive for long-term clinical failure independent of age, comorbidity, hypoxemia, and lung functional impairment in multivariate analysis (p = 0.005). The combination of copeptin and previous hospitalization for COPD increased the risk of poor outcome (p < 0.0001). Long-term clinical failure was observed in 11% of cases with copeptin < 40 pmol/L and no history of hospitalization, as compared to 73% of patients with copeptin >/= 40 pmol/L and a history of hospitalization (p < 0.0001).

CONCLUSIONS

We suggest copeptin as a prognostic marker for short-term and long-term prognoses in patients with AECOPD requiring hospitalization.

Dobutamine reverses the vasopressin-associated impairment in cardiac index and systemic oxygen supply in ovine endotoxemia

Introduction

Arginine vasopressin (AVP) is increasingly used to treat sepsis-related vasodilation and to decrease catecholamine requirements. However, AVP infusion may be associated with a marked decrease in systemic blood flow and oxygen transport. The purpose of the present study was to evaluate whether dobutamine may be titrated to reverse the AVP-related decrease in cardiac index (CI) and systemic oxygen delivery index (DO₂I) in an established model of ovine endotoxemia.

Methods

Twenty-four adult ewes were chronically instrumented to determine cardiopulmonary hemodynamics and global oxygen transport. All ewes received a continuous endotoxin infusion that contributed to a hypotensive-hyperdynamic circulation and death of five sheep. After 16 hours of endotoxemia, the surviving ewes (n = 19; weight 35.6 ± 1.5 kg (mean ± SEM)) were randomized to receive either AVP (0.04 Umin^-1) and dobutamine (n = 8) or the vehicle (normal saline; n = 6) and compared with a third group treated with AVP infusion alone (n = 5). Dobutamine infusion was started at an initial rate of 2 μg kg^-1min^-1 and was increased to 5 and 10 μg kg^-1 min^-1 after 30 and 60 minutes, respectively.

Results

AVP infusion increased mean arterial pressure (MAP) and systemic vascular resistance index at the expense of a markedly decreased CI (4.1 ± 0.5 versus 8.2 ± 0.3 l min^-1 m^-2), DO₂I (577 ± 68 versus 1,150 ± 50 ml min^-1 m^-2) and mixed-venous oxygen saturation (S_vO₂; 54.5 ± 1.8% versus 69.4 ± 1.0%; all p < 0.001 versus control). Dobutamine dose-dependently reversed the decrease in CI (8.8 ± 0.7 l min^-1 m^-2 versus 4.4 ± 0.5 l min^-1 m^-2), DO₂I (1323 ± 102 versus 633 ± 61 ml min^-1 m^-2) and S_vO₂ (72.2 ± 1.7% versus 56.5 ± 2.0%, all p < 0.001 at dobutamine 10 μg kg^-1 min^-1 versus AVP group) and further increased MAP.

Conclusion

This study provides evidence that dobutamine is a useful agent for reversing the AVP-associated impairment in systemic blood flow and global oxygen transport.

Short-term effects of glipizide (an adenosine triphosphate-sensitive potassium channel inhibitor) on cardiopulmonary hemodynamics and global oxygen transport in healthy and endotoxemic sheep

In severe sepsis and septic shock, hemodynamic support is often complicated by a tachyphylaxis against exogenous catecholamines. Because activation of adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels plays a pivotal role in the pathogenesis of hyperdynamic vasodilatory shock, we hypothesized that it may be beneficial to administer a specific K(ATP) channel inhibitor to prevent, or at least attenuate, hemodynamic dysfunction in sepsis. The present study was designed as a prospective and controlled laboratory experiment to elucidate the short-term effects of glipizide, a specific K(ATP) channel inhibitor, on cardiopulmonary hemodynamics and global oxygen transport in healthy sheep and sheep with endotoxemia. Ten adult ewes were anesthetized and operatively instrumented with a pulmonary artery, a femoral artery, and a foley catheter. After 24 h of recovery, healthy sheep received glipizide as a bolus infusion (4 mg/kg over 15 min). After 24 h of recovery, a continuous infusion of endotoxin (Salmonella typhosa, 10 ng.kg.(-1)min) was started in the same sheep and administered for the next 17 h. After 16 h of endotoxemia, glipizide was given as described above. Administration of glipizide was followed by a transient, but significant, increase in mean arterial pressure in both healthy controls (95 +/- 3 mmHg vs. 101 +/- 2 mmHg, P < 0.05) and sheep with endotoxemia (86 +/- 3 mmHg vs. 93 +/- 3 mmHg, P < 0.05). However, the increase in mean arterial pressure was longer lasting in ewes with endotoxemia. Cardiac index, oxygen delivery index, arterial lactate concentrations, and arterial pH were not significantly affected by glipizide. Therefore, administration of glipizide may represent a beneficial therapeutic option to treat arterial hypotension resulting from sepsis and systemic inflammatory response syndrome. Additional studies are required to determine the effects of continuous infusion of glipizide in the presence of systemic inflammation.