Management of vasodilatory shock: defining the role of arginine vasopressin

Factors associated with vasoplegic shock in the postoperative period of cardiac surgery and influence on morbidity and mortality of the use of arginine vasopressin as rescue therapy

OBJECTIVES

Analyzing associated factors with vasoplegic shock in the postoperative period of Cardiac Surgery. Analyzing the influence of vasopressin as rescue therapy to first-line treatment with norepinephrine.

DESIGN

Cohort, prospective and observational study.

SETTING

Main hospital Postoperative Cardiac ICU.

PATIENTS

Patients undergoing cardiac surgery with subsequent ICU admission from January 2021 to December 2022.

INTERVENTIONS

Record of presurgical, perioperative and ICU discharge clinical variables.

MAIN VARIABLES OF INTEREST

chronic treatment, presence of vasoplegic shock, need for vasopressin, cardiopulmonary bypass time, mortality.

RESULTS

773 patients met the inclusion criteria. The average age was 67.3, with predominance of males (65.7%). Post-CPB vasoplegia was documented in 94 patients (12.2%). In multivariate analysis, vasoplegia was associated with age, female sex, presurgical creatinine levels, cardiopulmonary bypass time, lactate level upon admission to the ICU, and need for prothrombin complex transfusion. Of the patients who developed vasoplegia, 18 (19%) required rescue vasopressin, associated with pre-surgical intake of ACEIs/ARBs, worse Euroscore score and longer cardiopulmonary bypass time. Refractory vasoplegia with vasopressin requirement was associated with increased morbidity and mortality.

CONCLUSIONS

Postcardiopulmonary bypass vasoplegia is associated with increased mortality and morbidity. Shortening cardiopulmonary bypass times and minimizing products blood transfusion could reduce its development. Removing ACEIs and ARBs prior to surgery could reduce the incidence of refractory vasoplegia requiring rescue with vasopressin. The first-line treatment is norepinephrine and rescue treatment with VSP is a good choice in refractory situations. The first-line treatment of this syndrome is norepinephrine, although rescue with vasopressin is a good complement in refractory situations.

A Clinical Review of Vasopressors in Emergency Medicine

BACKGROUND

Vasopressor medications raise blood pressure through vasoconstriction and are essential in reversing the hypotension seen in many critically ill patients. Previously, vasopressor administration was largely limited to continuous infusions through central venous access.

OBJECTIVES OF THE REVIEW

This review addresses the clinical use of vasopressors in various shock states, including practical considerations and innovations in vasopressor administration. The focus is on the clinical administration of vasopressors across a range of shock states, including hypovolemic, distributive, cardiogenic, and obstructive shock.

DISCUSSION

Criteria for starting vasopressors are not clearly defined, though early use may be beneficial. A number of physiologic factors affect the body's response to vasopressors, such as acidosis and adrenal insufficiency. Peripheral and push-dose administration of vasopressors are becoming more common. Distributive shock is characterized by inappropriate vasodilation and vasopressors play a crucial role in maintaining adequate blood pressure. The use of vasopressors is more controversial in hypovolemic shock, as the preferred treatment is correction of the volume deficit. Evidence for vasopressors is limited in cardiogenic shock. For obstructive shock, vasopressors can temporize a patient's blood pressure until definitive therapy can reverse the underlying cause.

CONCLUSION

Across the categories of shock states, norepinephrine has wide applicability and is a reasonable first-line agent for shock of uncertain etiology. Keeping a broad differential when hypotension is refractory to vasopressors may help to identify adjunctive treatments in physiologic states that impair vasopressor effectiveness. Peripheral administration of vasopressors is safe and facilitates early administration, which may help to improve outcomes in some shock states.

Photoswitchable Probes of Oxytocin and Vasopressin

Oxytocin (OT) and vasopressin (VP) are related neuropeptides that regulate many biological processes. In humans, OT and VP act via four G protein-coupled receptors, OTR, V1aR, V1bR, and V2R (VPRs), which are associated with several disorders. To investigate the therapeutic potential of these receptors, particularly in the receptor-dense areas of the brain, molecular probes with a high temporal and spatial resolution are required. Such a spatiotemporal resolution can be achieved by incorporating photochromic moieties into OT and VP. Here, we report the design, synthesis, and (photo)pharmacological characterization of 12 OT- and VP-derived photoprobes using different modification strategies. Despite OT's and VP's sensitivity toward structural changes, we identified two photoprobes with good potency and photoswitch window for investigating the OTR and V1bR. These photoprobes should be of high value for producing cutting-edge photocontrollable peptide probes for the study of dynamic and kinetic receptor activation processes in specific regions of the brain.

Association of Arterial pH With Hemodynamic Response to Vasopressin in Patients With Septic Shock: An Observational Cohort Study

OBJECTIVES

Vasopressin is reported to retain vasoconstrictive activity in the setting of acidemia, but preclinical models are inconsistent and studies have not evaluated the clinical effectiveness of vasopressin based on arterial pH. This study sought to determine the association between arterial pH and blood pressure after vasopressin initiation in septic shock.

DESIGN

This retrospective, multicenter, observational cohort study evaluated the association of arterial pH at the time of vasopressin initiation with hemodynamic response to vasopressin and change in catecholamine dose after vasopressin initiation. Hemodynamic response was defined as a catecholamine dose decrease with mean arterial pressure greater than or equal to 65 mm Hg at 6 hours after vasopressin initiation.

SETTING

Patients from eight hospitals in a health system were evaluated.

PATIENTS

Patients with septic shock initiated on vasopressin as a catecholamine adjunct between January 2012 and November 2017 were screened for inclusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 1,350 patients were included. At the time of vasopressin initiation patients were severely ill with arterial pH 7.28 ± 0.13, Sequential Organ Failure Assessment 14.1 ± 3.5, lactate 5.6 ± 4.6 mmol/L, and norepinephrine-equivalent catecholamine dose 32.3 ± 25.4 µg/min. After adjusting for lactate and Sequential Organ Failure Assessment with multivariable logistic regression, lower arterial pH was independently associated with lower odds of hemodynamic response to vasopressin (for each 0.1 unit arterial pH was below 7.40, response odds ratio 0.79; 95% CI, 0.72-0.87). For each 0.1 unit the pH was below 7.40 at vasopressin initiation, the norepinephrine-equivalent catecholamine dose increased by 1.5 µg/min (95% CI, 0.5-2.5 µg/min) at 1 hour, and increased by 2.5 µg/min (95% CI, 1.4-3.5 µg/min) at 6 hours after vasopressin initiation.

CONCLUSIONS

Compared with higher arterial pH, patients with septic shock and low arterial pH had lower odds of vasopressin response and higher catecholamine doses after vasopressin initiation. Similar to other vasopressors, the clinical effectiveness of vasopressin appears to be impaired in the setting of acidemia.

Prognostic performance of copeptin among patients with acute decompensated heart failure

BACKGROUND

In heart failure (HF), various biomarkers have been established for prognosis. However, little is known about the relevance of copeptin measurements to HF. This study aimed to explore the prognostic value of copeptin for predicting cardiovascular (CV) death or HF-related re-hospitalisation in patients with acute decompensated HF.

MATERIALS AND METHODS

We prospectively enrolled 155 consecutive patients with acute signs and symptoms of HF. Plasma copeptin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were measured at admission. Patients were monitored for 90 days regarding the composite endpoint of CV death or acute HF-related re-hospitalisation.

RESULTS

Of the 155 patients enrolled, 40 reached the endpoint, and 115 were in a stable condition during follow-up. Patients who reached an adverse endpoint showed higher NT-proBNP and copeptin levels compared to patients in stable condition. Receiver operating characteristic curve analysis revealed that the area under curve of copeptin 0.844 (95% CI, 0.753-0.935) was superior to that of NT-proBNP 0.809 (95% CI, 0.729-0.890) for the prediction of adverse events within 90 days. Meanwhile, compared to the group with lower copeptin levels (<34 pmol/L), patients with higher copeptin levels (≥34 pmol/L) were at a 10.672-times higher risk of CV death or acute HF-related re-hospitalisation. Multivariate Cox proportional hazards regression analysis revealed that increased copeptin level was a significantly independent predictor of adverse events (risk ratio, 1.051; 95% CI, 1.020-1.083; p < 0.001).

CONCLUSION

Copeptin was found to be a strong, novel marker for predicting CV death or HF-related re-hospitalisation in patients with acute decompensated HF.

Low vasopressin and progression of neonatal sepsis to septic shock: a prospective cohort study

The study objective was to analyze the association between low plasma vasopressin and progression of sepsis to septic shock in neonates < 34 weeks gestation. Septic neonates of < 34 weeks gestation were consecutively enrolled; moribund neonates and those with major malformations were excluded. Subjects were monitored for progression of sepsis to septic shock over the first 7 days from enrolment. Plasma vasopressin levels and inducible nitric oxide synthase levels were measured at the onset of sepsis (T0), severe sepsis (T1), and septic shock (T2). Primary outcome was plasma vasopressin levels at the point of sepsis in those who progressed to septic shock in comparison with matched nested controls in the non-progression group. Forty-nine (47%) enrolled subjects developed severe sepsis or septic shock. Plasma vasopressin levels (pg/ml) at the onset of sepsis were significantly low in those who progressed to septic shock (median (IQR), 31 (2.5-80) versus 100 (12-156); p = 0.02). After adjusting for confounders, vasopressin levels were independently associated with progression to septic shock (adjusted OR (95% CI), 0.97 (0.96, 0.99); p = 0.01).Conclusion: Preterm septic neonates who progressed to septic shock had suppressed vasopressin levels before the onset of shock. Low vasopressin levels were independently associated with progression to septic shock.What is known:• In animal sepsis models and adult septic patients, exuberant production of nitric oxide metabolites and low vasopressin levels have been reportedly associated with progression to septic shock.• Vasopressin levels have been variably reported as low as well as elevated in children with septic shock.What is New:• Preterm neonates who progressed from sepsis to septic shock had significantly lower levels of vasopressin before the onset of shock in comparison with those who did not progress.• Low vasopressin levels independently predicted the progression from sepsis to septic shock in this population.

Association between Serum Copeptin and Stroke in Rural Areas of Northern China: A Matched Case-Control Study

Background

Copeptin has been implicated as an effective prognostic biomarker of stroke outcome; however, few studies have investigated whether copeptin could be used as an etiological factor for stroke or not. The aim of our study was to evaluate the association of serum copeptin with stroke.

Methods

In total, 238 participants including 119 cases (87 ischemic stroke and 32 hemorrhagic stroke) and 119 controls were included in this 1 : 1 matched case-control study. Conditional multivariate logistic regression was conducted to assess the Odds Ratios (ORs) and 95% confidence intervals (CI); restricted cubic spline in logistic regression model was used to evaluate the dose-response association between serum copeptin and total stroke, ischemic stroke, and hemorrhagic stroke.

Results

The median serum copeptin was 20.90 pmol/L, 20.90 pmol/L, 6.53 pmol/L, and 8.42 pmol/L for total stroke, ischemic stroke, hemorrhagic stroke, and healthy subjects, respectively. The corresponding ORs (95% CIs) for the highest compared with the lowest quartile were 1.23 (0.62–2.44) for total stroke, 4.01 (1.47–10.96) for ischemic stroke, and 0.13 (0.22–0.69) for hemorrhagic stroke. No nonlinear dose-response relationship was found between serum copeptin and total stroke (P_nonlinear = 0.278), ischemic stroke (P_nonlinear = 0.362), and hemorrhagic stroke (P_nonlinear = 0.314). Compared with the reference copeptin level, a significantly increasing trend was found between serum copeptin and ischemic stroke (P_overall = 0.002), and a decreasing trend was found between serum copeptin and hemorrhagic stroke (P_overall = 0.007).

Conclusions

Elevated serum copeptin levels were positively associated with ischemic stroke and adversely associated with hemorrhagic stroke. Additional prospective studies with larger sample size are needed to confirm the present findings.

Plasma copeptin levels in the patients with gastrointestinal bleeding

INTRODUCTION

Gastrointestinal bleeding is a significant cause of morbidity and mortality worldwide. In addition, it constitutes an important part of health expenditures. In this study, we aimed to determine whether there is a relationship between plasma copeptin levels and the etiology, location and severity of gastrointestinal bleeding.

MATERIALS AND METHODS

This study was performed prospectively in 104 consecutive patients who were admitted to an emergency department with complaints of bloody vomiting or bloody or black stool. To evaluate the level of biochemical parameters such as Full Blood Count (FBC), serum biochemistry, bleeding parameters and copeptin, blood samples were obtained at admission. For the copeptin levels, 2 more blood samples were obtained at the 12th and 24th hours after admission. The values obtained were compared using statistical methods.

RESULTS

In terms of the etiology of bleeding, the copeptin levels in the patients with peptic ulcer were higher than the levels in patients with other gastrointestinal bleeding. However, the difference was not statistically significant. There were no significant differences among all groups' 0th, 12th and 24th hour levels of copeptin.

DISCUSSION

We conclude that copeptin cannot be effectively used as a biochemical parameter in an emergency department to determine the etiology and location of gastrointestinal bleeding. It can, however, be used to make decisions on endoscopy and the hospitalization of patients with suspected gastrointestinal bleeding.

Prognostic role of copeptin with all-cause mortality after heart failure: a systematic review and meta-analysis

BACKGROUND

As the C-terminal section of vasopressin precursor, copeptin has been recently suggested as a new prognostic biomarker after heart failure (HF). Thus, the aim of this study was to evaluate the prognostic value of plasma copeptin level with all-cause mortality in patients with HF.

METHODS

Comprehensive strategies were used to search relevant studies from electronic databases. Pooled hazard ratios (HRs) and standardized mean differences (SMDs) together with their 95% confidence intervals (CIs) were calculated. Subgroup analysis and sensitivity analysis were performed to find the potential sources of heterogeneity.

RESULTS

A total of 5,989 participants from 17 prospective studies were included in this meta-analysis. A significant association was observed between circulating copeptin levels and risk of all-cause mortality in patients with HF (categorical copeptin: HR =1.69, 95% CI =1.42-2.01; per unit copeptin: HR =1.03, 95% CI =1.00-1.07; log unit copeptin: HR =3.26, 95% CI =0.95-11.25). Pooled SMD showed that copeptin levels were significantly higher in patients with HF who died during the follow-up period than in survivors (SMD =1.19, 95% CI =0.81-1.57). Subgroup analyses also confirmed this significant association, while sensitivity analyses indicated that the overall results were stable.

CONCLUSION

This study demonstrated that circulating copeptin seemed to be a novel biomarker to provide better prediction of all-cause mortality in patients with HF.

Identification of patients at risk for preeclampsia with the use of uterine artery Doppler velocimetry and copeptin

PURPOSE

To investigate the relationship between maternal copeptin levels and uterine artery Doppler examination and progress of preeclampsia.

MATERIALS AND METHODS

A cross-sectional study was designed with women those were screened at 20 + 0 - 24+  6 weeks' gestation between May 2014 and August 2014. The obstetric records of all normotensive women were examined. Uterine artery Doppler velocimetry results and serum copeptin levels were measured. The patients were divided into two groups according to normal (n = 67) and abnormal uterine artery Doppler (n = 21) findings.

RESULTS

Maternal age was significantly lower in group 1 (n = 21, 23.9%) than in group 2 (n= 67, 76.1%) (p < 0.05). We found no differences in maternal characteristics, birth weight, gestational age at delivery and copeptin levels between the two groups. Maternal serum copeptin levels were higher in women who subsequently developed preeclampsia. There was also a significant correlation between copeptin levels and the presence of preeclampsia. (p = 0.002).

CONCLUSIONS

Copeptin levels are significantly higher in patients who develop preeclampsia.

Thromboembolic Events During Continuous Vasopressin Infusions: A Retrospective Evaluation

Background:

Published guidelines suggest that vasopressin has a role in shock treatment, although its safety has not been adequately evaluated in a clinical setting. Vasopressin causes platelet aggregation and has been associated with the release of factor VIII coagulant and von Willebrand factor.

Objective:

To compare the incidence of venous thromboembolism (VTE) in patients with a diagnosis of shock who received vasopressin with those who did not receive vasopressin for hemodynamic support.

Methods:

A retrospective, single-center, cohort study was conducted at an academic, tertiary care center with 350 patients with a diagnosis of shock. Patients from the intensive care unit were randomly selected and separated into 2 groups for comparison of those receiving only catecholamines with those receiving vasopressin with or without catecholamines for hypotension. Patients with diabetes insipidus or variceal hemorrhage and those with any documented history of VTE were excluded. The primary outcome, VTE occurrence, was defined as a positive Doppler ultrasound, spiral computed tomography, or documented diagnosis in the discharge records. Frequency and type of risk factors for VTE were compared between the 2 study arms. A risk factor modeling approach was performed, using logistic regression to identify potential confounders and effect modifiers in the relationship between vasopressin and VTE.

Results:

There were 175 patients in each arm of the study. The crude incidence of VTE was 7.4% and 8% in the vasopressin and catecholamine groups, respectively (p = 0.84). No significant difference in the incidence of deep venous thrombosis (vasopressin 5.1%, control 7.4%; p = 0.51) or pulmonary embolism (vasopressin 2.3%, control 0.6%; p = 0.37) was found between groups. After adjusting for covariates, there was no statistically significant difference in the incidence of VTE between the 2 arms (p = 0.72).

Conclusions:

This investigation provides initial evidence that vasopressin infusions do not increase the risk of VTE in patients with shock.

Vasopressin in Pediatric Critical Care

Vasopressin is a unique hormone with complex receptor physiology and numerous physiologic functions beyond its well-known vascular actions and osmoregulation. While vasopressin has in the past been primarily used in the management of diabetes insipidus and acute gastrointestinal bleeding, an increased understanding of the physiology of refractory shock, and the role of vasopressin in maintaining cardiovascular homeostasis prompted a renewed interest in the therapeutic roles for this hormone in the critical care setting. Identifying vasopressin-deficient individuals for the purposes of assessing responsiveness to exogenous hormone and prognosticating outcome has expanded research into the evaluation of vasopressin and its precursor, copeptin as useful biomarkers. This review summarizes the current evidence for vasopressin in critically ill children, with a specific focus on its use in the management of shock. We outline important considerations and current guidelines, when considering the use of vasopressin or its analogues in the pediatric critical care setting.

Impairment of the Vascular KATP Channel Imposes Fatal Susceptibility to Experimental Diabetes Due to Multi-Organ Injuries

The vascular isoform of ATP-sensitive K(+) (KATP ) channels regulates blood flow to all organs. The KATP channel is strongly inhibited by reactive oxygen and carbonyl species produced in diabetic tissue inflammation. To address how such channel inhibition impacts vascular regulation as well as tissue viability, we performed studies in experimental diabetic mice. Strikingly, we found that knockout of the Kcnj8 encoding Kir6.1 subunit (Kcnj8-KO) caused mice to be fatally susceptible to diabetes. Organ perfusion studies suggested that the lack of this vascular K(+) channel handicapped activity-dependent vasodilation, leading to hypoperfusion, tissue hypoxia, and multi-organ failure. Morphologically, Kcnj8-KO mice showed greater inflammatory cell infiltration, higher levels of expression of inflammation indicator proteins, more severe cell apoptosis, and worse tissue disruptions. These were observed in the kidney, liver, and heart under diabetic condition in parallel comparison to tissues from WT mice. Patch clamping and molecular studies showed that the KATP channel was S-glutathionylated in experimental diabetes contributing to the inhibition of channel activity as well as the reduced arterial responses to vasodilators. These results suggest that the vascular KATP channel is organ protective in diabetic condition, and since the channel is suppressed by diabetic oxidative stress, therapeutical interventions to the maintenance of functional KATP channels may help to lower or prevent diabetic organ dysfunction.

Copeptin: Limited Usefulness in Early Stroke Differentiation?

Background. Stroke can be a challenging diagnosis in an emergency-setting. We sought to determine whether copeptin may be a useful biomarker to differentiate between ischemic stroke (IS), transient ischemic attack (TIA), and stroke-mimics. Methods. In patients with suspected stroke arriving within 4.5 hours of symptom-onset, copeptin-levels were measured in initial blood-samples. The final diagnosis was adjudicated by vascular neurologists blinded to copeptin-values. Results. Of all 36 patients with available copeptin-values (median age 71 years, IQR: 54–76; 44% female), 20 patients (56%) were diagnosed with IS, no patient was diagnosed with hemorrhagic stroke, nine patients (25%) were diagnosed with TIA, and seven patients (19%) were stroke-mimics. Copeptin-levels (in pmol/L) tended to be higher in patients with IS [19.1 (11.2–48.5)] compared to TIA [9.4 (5.4–13.8)]. In stroke-mimics the range of values was extremely broad [33.3 (7.57–255.7)]. The diagnostic accuracy of copeptin for IS was 63% with a sensitivity of 80% and a positive predictive value of 64%. Conclusion. In this cohort of patients copeptin-levels within 4.5 hours of symptom onset were higher in patients with IS compared to TIA but the broad range of values in stroke-mimics limits diagnostic accuracy. This trial is registered with UTN: U1111-1119-7602.

Prediction of all-cause mortality with copeptin in cardio-cerebrovascular patients: A meta-analysis of prospective studies

BACKGROUND

Measurement of the biomarker copeptin may help identify disease severity and risk of mortality for a various diseases. This study sought to determine the relationship between copeptin and all-cause mortality of patients with cardio-cerebrovascular disease.

METHODS

Database of Medline and Web of Science were searched for studies with data involving the baseline copeptin levels and subsequent all-cause mortality outcomes. The pooled HRs of all-cause mortality were calculated and presented with 95%CIs. Subgroup analysis and sensitivity analysis were conducted to explore the possible sources of heterogeneity.

RESULTS

Data from 14,395 participants were derived from 28 prospective studies. Higher copeptin significantly increased the risk of all-cause mortality (per unit copeptin: HR=1.020, 95%CI=1.004-1.036; log unit copeptin: HR=2.884, 95%CI=1.844-4.512; categorical copeptin: HR=3.371, 95%CI=2.077-5.472). Subgroup analysis indicated that the risk of all-cause death was higher in cerebrovascular patients (per unit copeptin: HR=2.537, 95%CI=0.956-6.731; log unit copeptin: HR=3.419, 95%CI=2.391-4.888) than cardiovascular patients (per unit copeptin: HR=1.011, 95%CI=1.002-1.020; log unit copeptin: HR=2.009, 95%CI=1.119-3.608).

CONCLUSION

Copeptin is associated with all-cause mortality of patients with cardiovascular and cerebrovascular disease. Our study suggests that copeptin seems to be a promising novel biomarker for prediction of mortality in cardio-cerebrovascular patients, especially for cerebrovascular patients.

Vasopressin in hemorrhagic shock: a systematic review and meta-analysis of randomized animal trials

Objective. The latest European guidelines for the management of hemorrhagic shock suggest the use of vasopressors (norepinephrine) in order to restore an adequate mean arterial pressure when fluid resuscitation therapy fails to restore blood pressure. The administration of arginine vasopressin (AVP), or its analogue terlipressin, has been proposed as an alternative treatment in the early stages of hypovolemic shock. Design. A meta-analysis of randomized controlled animal trials. Participants. A total of 433 animals from 15 studies were included. Interventions. The ability of AVP and terlipressin to reduce mortality when compared with fluid resuscitation therapy, other vasopressors (norepinephrine or epinephrine), or placebo was investigated. Measurements and Main Results. Pooled estimates showed that AVP and terlipressin consistently and significantly improve survival in hemorrhagic shock (mortality: 26/174 (15%) in the AVP group versus 164/259 (63%) in the control arms; OR = 0.09; 95% CI 0.05 to 0.15; P for effect < 0.001; P for heterogeneity = 0.30; I₂ = 14%). Conclusions. Results suggest that AVP and terlipressin improve survival in the early phases of animal models of hemorrhagic shock. Vasopressin seems to be more effective than all other treatments, including other vasopressor drugs. These results need to be confirmed by human clinical trials.

Copeptin is not a useful biomarker for small-for-gestational-age: a case control study

OBJECTIVE

To investigate copeptin as a biomarker for small-for-gestational-age.

METHODS

We conducted a nested case-control study on maternal copeptin levels measured in gestational week 12 and 19 and risk of small-for-gestational age. Cases were defined as pregnant women who delivered a small-for-gestational-age infant. Small-for-gestational age was defined as a birth weight - 22% or less than expected according to gestational age (n = 39). Controls were pregnant women who delivered a normal-weight infant (n = 119). The copeptin ultrasensitive Kryptor kit (BRAHMS) was used to determine copeptin in maternal serum. We established reference ranges for copeptin by 95% prediction intervals with 90% confidence intervals. Paired and unpaired t-tests were performed to test the null-hypothesis of no difference in copeptin levels within and between the groups.

RESULTS

The reference intervals for copeptin in normal pregnancies were 1.24-5.51 pmol/L (90% confidence intervals on upper and lower limit were 1.13-1.37 and 5.00-6.08 pmol/L) at gestational week 12, and 1.30-5.09 pmol/L (90% confidence intervals were 1.19-1.42 and 4.65-5.57 pmol/L) at gestational week 19. Copeptin levels decreased from week 12-19 in cases (p = 0.02), whereas no change was observed in controls (p = 0.61). We found no difference in copeptin levels in cases compared to controls in gestational week 12 (p = 0.10) and week 19 (p = 0.81).

CONCLUSION

The present study could not demonstrate copeptin as a novel biomarker for small-for-gestational-age.

The Bellamy challenge: it's about time

In 1984, Col. Ronald Bellamy launched a worldwide challenge to develop a new resuscitation fluid to aid survival after catastrophic blood loss on the battlefield. In 1996, after careful compromise among need, cube weight and efficacy, the US military and later coalition forces adopted 6% hetastarch (HES) fluids for early resuscitation. In the intervening years, evidence has amassed indicating that the HES fluids may not be safe, and in June 2013 the US Food and Drug Administration issued a warning that HES solutions should not be used to treat patients with hypovolaemia or the critically ill. We review the unique challenges of early battlefield resuscitation, why the 'Bellamy challenge' remains open and discuss a number of forward-looking strategies that may help to solve the problem. The first two pillars of resuscitation that we believe have not been adequately addressed are rescuing and stabilising the heart (and brain) and the vascular system. The 'ideal' resuscitation fluid needs to nurture the heart and body slowly back to health, and not 'shock' it a second time with unnatural colloids or large volumes of unphysiological saline-based solutions.

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.

Vasopressin and Terlipressin in the Treatment of Vasodilatory Septic Shock: A Systematic Review

Background:

Vasodilatory septic shock unresponsive to fluid resuscitation requires the addition of vasopressors. Catecholamines remain the first line vasopressor therapy, but treatment failure is a potential problem. Vasopressin and its analogue, terlipressin, have been used for this indication.

Objective:

This systematic review aims to evaluate the effects of vasopressin and terlipressin on mortality and morbidity outcomes in patients with vasodilatory shock. Secondary outcomes include the effects of vasopressin and terlipressin on haemodynamic stability and organ function.

Method:

A computerised search of MEDLINE from January 1966 till June 2010 and screening of references of relevant articles were conducted. Only prospective, randomised controlled trials comparing vasopressin or terlipressin versus standard vasopressors or placebo were included.

Results:

Seven studies using vasopressin, three using terlipressin and one using both were identified. Four vasopressin trials assessing mortality and morbidity outcomes showed a trend towards benefit for mortality in adults but possibly adverse outcomes in a small paediatric study. No data was available on the long-term mortality and morbidity outcomes of terlipressin. Vasopressin and terlipressin were similar to standard vasopressors in maintaining haemodynamic parameters, while allowing a beneficial catecholamine-sparing effect. These agents also had a neutral to positive effect on organ function.

Conclusion:

Vasopressin and terlipressin was comparable to conventional agents in the maintenance of haemodynamic stability and organ function in vasodilatory shock. Since morbidity and mortality data do not differentiate vasopressin and terlipressin from catecholamines, their role remains unclear. More large studies evaluating the long-term outcomes in this group of patients are required.

Co-peptin: Role as a novel biomarker in clinical practice

BACKGROUND

Arginine vasopressin (AVP) is a key regulator of water balance, but its instability makes reliable measurement difficult and precludes its routine use. Co-peptin is the C-terminal part of the AVP precursor which plays an important role in the correct structural formation of the AVP precursor and its efficient proteolytic maturation. Because of its stoichiometric generation, co-peptin mirrors the release of AVP and measurement of more stable co-peptin may be an indicator of AVP levels.

METHOD

A comprehensive literature search was conducted from the websites of the National Library of Medicine (http://www.ncbl.nlm.nih.gov) and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature (http://www.pubmedcentral.nih.gov/). The data was assessed from books and journals that published relevant articles in this field.

RESULT

Recent and ongoing research indicates the diagnostic and prognostic roles of co-peptin in various clinical settings especially in critically ill patients.

CONCLUSION

Co-peptin levels are altered in various physiological and pathological conditions indicating its possible role as a biomarker. However, further research using co-peptin in various clinical settings will prove its cost-effectiveness and clinical usefulness.

Preventing cardiac arrest during hemorrhagic shock with vasopressin

The optimal strategy of stabilizing hemodynamic function in uncontrolled traumatic hemorrhagic shock states is unclear. Although fluid replacement is established in controlled hemorrhagic shock, its use in uncontrolled hemorrhagic shock is controversial, because it may worsen bleeding. In the refractory phase of severe hemorrhagic shock, arginine vasopressin has been shown to be beneficial in selected cases due to an increase in arterial blood pressure, shift of blood away from a subdiaphragmatic bleeding site toward the heart and brain, and decrease in fluid-resuscitation requirements. Especially in patients with severe traumatic brain injury, rapid stabilization of cardiocirculatory function is essential to ensure adequate brain perfusion, thus, to prevent neurologic damage and to improve outcome. In addition, despite wide distribution of highly developed and professional emergency medical systems in western industrialized countries, survival chances of patients with uncontrolled traumatic hemorrhagic shock in the preclinical setting are still poor.

Low-dose vasopressin infusion therapy for refractory hypotension in ELBW infants

BACKGROUND

Severe hypotension in infants, especially in preterm infants, is associated with poor neurological outcome and high mortality. In adults, low-dose vasopressin (arginine vasopressin: AVP) infusion therapy has been effective for treating hypotension that is refractory to vasopressors and inotropes.

METHODS

The effects of AVP infusion therapy for refractory hypotension were retrospectively evaluated in extremely low-birthweight infants. Between January 2002 and November 2005, 22 infants with refractory hypotension treated with low-dose AVP infusion were reviewed. The average birthweight was 658 g (+/-142 g), and the average gestational age was 24.9 weeks (+/-1.4). The changes in blood pressure, urinary output, and other parameters in response to AVP therapy were analyzed in all the infants.

RESULTS

After AVP infusion, systolic blood pressure increased from 30 mmHg to 43 mmHg (P < 0.0001), and the diastolic pressure increased from 15 mmHg to 24 mmHg (P < 0.0001). The urine output dramatically increased from 1.5 mL/kg per h to 4.0 mL/kg per h (P < 0.0001). AVP infusion, however, was not effective in four of the 22 patients (18%). The sodium concentration in the serum decreased mildly after administration. In six patients the serum sodium concentration decreased below 130 mEq/L. Severe mitral regurgitation was observed in two patients. Three infants showed a transient decrease in the platelet count during AVP infusion.

CONCLUSIONS

Low-dose AVP therapy should be considered as rescue therapy when high-dose catecholamine therapy and/or steroid administration do not produce sufficient increase in the blood pressure. Further investigations are required to prove the efficacy and safety of AVP infusion therapy in preterm infants.

Perioperative infusion of low- dose of vasopressin for prevention and management of vasodilatory vasoplegic syndrome in patients undergoing coronary artery bypass grafting-A double-blind randomized study

Preoperative medication by inhibitors of angiotensin-converting enzyme (ACE) in coronary artery patients predisposes to vasoplegic shock early after coronary artery bypass grafting. Although in the majority of the cases this shock is mild, in some of them it appears as a situation, "intractable" to high-catecholamine dose medication. In this study we examined the possible role of prophylactic infusion of low-dose vasopressin, during and for the four hours post-bypass after cardiopulmonary bypass, in an effort to prevent this syndrome. In addition, we studied the influence of infused vasopressin on the hemodynamics of the patients, as well as on the postoperative urine-output and blood-loss. In our study 50 patients undergoing coronary artery bypass grafting were included in a blind-randomized basis. Two main criteria were used for the eligibility of patients for coronary artery bypass grafting: ejection fraction between 30-40%, and patients receiving ACE inhibitors, at least for four weeks preoperatively. The patients were randomly divided in two groups, the group A who were infused with 0.03 IU/min vasopressin and the group B who were infused with normal saline intraoperativelly and for the 4 postoperative hours. Measurements of mean artery pressure (MAP), central venous pressure (CVP), systemic vascular resistance (SVR), ejection fracture (EF), heart rate (HR), mean pulmonary artery pressure (MPAP), cardiac index (CI) and pulmonary vascular resistance (PVR) were performed before, during, and after the operation. The requirements of catecholamine support, the urine-output, the blood-loss, and the requirements in blood, plasma and platelets for the first 24 hours were included in the data collected. The incidence of vasodilatory shock was significantly lower (8% vs 20%) in group A and B respectively (p = 0,042). Generally, the mortality was 12%, exclusively deriving from group B. Postoperatively, significant higher values of MAP, CVP, SVR and EF were recorded in the patients of group A, compared to those of group B. In group A norepinephrine was necessary in fewer patients (p = 0.002) and with a lower mean dose (p = 0.0001), additive infusion of epinephrine was needed in fewer patients (p = 0.001), while both were infused for a significant shorter infusion-period (p = 0.0001). Vasopressin administration (for group A) was associated with a higher 24 hour diuresis) (0.0001).

In conclusion, low-dose of infused vasopressin during cardiopulmonary bypass and for the next 4 hours is beneficial for its postoperative hemodynamic profile, reduces the doses of requirements of catecholamines and contributes to prevention of the postcardiotomy vasoplegic shock in the patient with low ejection fraction who is receiving ACE preoperatively.

Vasoplegic syndrome during liver transplantation

A 56-yr-old woman with chronic hepatitis B and decompensated hepatic cirrhosis was treated with liver transplantation. At the beginning of the neohepatic phase, her arterial blood pressure remained at 60/40 mm Hg for approximately 40 min and did not respond to vasoconstrictive drugs. Her other clinical and laboratory values remained normal, apart from a high cardiac output and low systemic vascular resistance. This patient was diagnosed with vasoplegic syndrome and was treated with i.v. infusion of methylene blue (0.5 mg/kg) and norepinephrine. This report has potential significance to treatment in patients who undergo orthotopic liver transplantation.

Naloxone combined with epinephrine decreases cerebral injury in cardiopulmonary resuscitation

BACKGROUND

Cardiopulmonary arrest is a serious disease that claims many lives every day; 30% of the patients suffer irreversible central nervous system injury after restoration of systemic circulation (ROSC).

OBJECTIVES

Naloxone combined with epinephrine was tested in a cardiac arrest rat model in which asphyxia was induced to determine if this drug combination could increase the resuscitation rate (survival) and decrease the cerebral damage.

METHODS

Twenty-four male Wistar rats were randomly assigned to one of three groups: the group treated with 1 mL saline (SA group; n = 8), the group treated with only epinephrine 5 microg/100 g (EP group; n = 8), or the group treated with epinephrine 5 microg/100 g combined with naloxone 1 mg/kg (NA group; n = 8). Eight minutes after arrest, cardiopulmonary resuscitation was initiated and the different drugs were administered to the rats in their respective groups at the same time. Mean arterial pressure (MAP), heart rate (HR), and neurodeficit score (NDS) were measured.

RESULTS

The HR in the NA group (414 +/- 45 beats/min) was faster than in the EP group (343 +/- 29 beats/min) at the 5-min time point (P < 0.01). The HR in the NA group was 392 +/- 44 beats/min and 416 +/- 19 beats/min at the 60-min and 180-min time points, respectively. There were no statistically significant differences in MAP before or after ROSC. The rates of ROSC were 2 of 8, 6 of 8, and 7 of 8 animals in the SA group, EP group, and NA group, respectively. Three days later, the rates decreased to 1, 3, and 5 in the SA group, EP group, and NA group, respectively. The average resuscitation time in the NA group was significantly shorter than in the other two groups. The NDS in the NA group was 57 +/- 13, higher than in the EP group (45 +/- 13) and SA group (38).

CONCLUSION

Naloxone combined with epinephrine significantly increased the resuscitation rate in a rat model. Furthermore, the combination of naloxone and epinephrine increased the NDS after cardiopulmonary resuscitation.

Gender and renal function influence plasma levels of copeptin in healthy individuals

The present study sought to identify confounding factors for the interpretation of copeptin levels in healthy individuals. The natriuretic peptides are recognized as diagnostic and prognostic tools in HF (heart failure). Interpretation of BNP (brain natriuretic peptide) and NTproBNP (N-terminal pro-BNP) levels is multifaceted as their secretion is influenced by many variables. A newly identified glycopeptide called copeptin is comparable with the natriuretic peptides in the diagnosis and prognosis of HF and as a prognostic biomarker after AMI (acute myocardial infarction). Copeptin, derived from the C-terminal portion of the precursor to AVP (arginine vasopressin), is secreted stoichiometrically with vasopressin, hence it can be used as a surrogate marker of the AVP system. In the present study, 706 healthy volunteers were recruited from a local HF screening study. Participants with a history of cardiovascular disease and those with echocardiographic abnormalities were excluded from the study. Copeptin and NTproBNP levels were assayed using in-house immunoluminometric assays. Median copeptin levels were significantly higher in the male volunteers compared with the females [median (range): 4.3 (0.4-44.3) compared with 3.2 (1.0-14.8) pmol/l; P<0.001]. In males, copeptin was correlated with eGFR (estimated glomerular filtration rate; r(s)=-0.186, P<0.001). In females, the correlation of copeptin with eGFR was weak (r(s)=-0.097, P=0.095). DT (deceleration time) and left atrial size correlated with higher copeptin levels (r(s)=0.085, P=0.029 and r(s)=0.206, P<0.001 respectively). Only gender (P<0.001), eGFR (P<0.001), left atrial size (P=0.04) and DT (P=0.02) remained independently predictive of plasma copeptin. The present study suggests that gender and renal function specific partition values should be used to interpret copeptin values in future studies of this biomarker in HF or ischaemic heart disease.

Vasopressin as adjunct vasopressor for vasodilatory shock due to non-occlusive mesenteric ischemia

We present the case of an 83-year-old patient who underwent cardiac surgery and developed postoperative non-occlusive mesenteric ischemia (NOMI), which was treated with a local intra-arterial papaverine and prostaglandin E1 infusion. After successful mesenteric reperfusion, a multiple organ dysfunction syndrome with severe cardiovascular failure developed. High norepinephrine dosages (1.09 microg/kg body weight/min) and catecholamine-related complications (tachycardiac atrial fibrillation) required initiation of supplementary argininevasopressin (AVP) infusion (4 U/h). AVP stabilized vasodilatory shock, ensured adequate gut perfusion pressure and had no adverse clinical or angiographic effects on restitution of gut integrity. In conclusion, after reperfusion of NOMI in this patient, adjunct AVP therapy combined with local vasodilator infusion was beneficial as a potentially life-saving vasopressor.

Vasopressin in the pediatric cardiac intensive care unit: Myth or reality

Pediatric cardiac surgery is undergoing a metamorphosis, with more and more critical patients being operated in our country today. Although the principles of physiology have not changed, it is imperative that care providers continue to stay abreast with developments and newer drugs that may help modify the outcome. The team dynamics have also become more complex, which necessitates the need for all care providers (surgeons, cardiologists, anesthesiologists, and intensivists) to better understand the interactions and benefits of newer drugs. Vasopressin has been used in our adult patients for more than a decade and recently has found its rightful place in the pediatric armoury. The objective of this article is to review the physiology of vasopressin and the rationale of its use in critically ill children with shock, in context of the available published data.

[Microcirculation of intensive care patients. From the physiology to the bedside]

The microcirculation is unique in its anatomy and physiology and is a self-contained organ system within the human body. It is the site where gas exchange and nutrient supply takes place, but it is also the site which experiences pathological alterations during various shock states and therefore compromises the oxygen supply to tissues and organs. Systemic inflammation for example leads amongst others to increased heterogeneous blood flow, formation of interstitial edema, altered viscosity, leukocyte activation, disturbances in the coagulation system, and to a breakdown of the endothelial barrier function. These alterations inevitably lead to limitations of the oxygen supply to tissues. Without interruption of these pathomechanisms, the dysfunction of the microcirculation will consequently result in organ dysfunction. In this review article a short description of the microcirculatory physiology, the interaction between the macrocirculation and the microcirculation, as well as microcirculatory alterations generated by a systemic inflammatory response will be given. Finally, various therapy options will be described, which, experimentally, can lead to an improvement in microcirculatory dysfunction.

The use of vasopressin in the setting of recalcitrant hypotension due to calcium channel blocker overdose

Treatment of hypotension caused by calcium channel blocker overdose (CCB) remains a challenge. We describe the successful use of vasopressin in two patients with massive CCB overdoses in whom hypotension was unresponsive to calcium, glucagon, insulin, and conventional vasopressor therapies. While various modes of treatments have been used to treat the hypotension of CCB overdose, this is the first report to our knowledge of the successful use of vasopressin in this clinical setting.

Developing alternative strategies for the treatment of traumatic haemorrhagic shock

PURPOSE OF REVIEW

The optimal strategy of stabilizing haemodynamic function in uncontrolled traumatic haemorrhagic shock states is unclear. Although fluid replacement is established in controlled haemorrhagic shock, its use in uncontrolled haemorrhagic shock is controversial, because it may worsen bleeding.

RECENT FINDINGS

In the refractory phase of severe haemorrhagic shock, arginine vasopressin has been shown to be beneficial in selected cases due to an increase in arterial blood pressure, shift of blood away from a subdiaphragmatic bleeding site towards the heart and brain, and decrease in fluid resuscitation requirements. Especially in patients with severe traumatic brain injury, rapid stabilization of cardiocirculatory function is essential to ensure adequate brain perfusion and thus to prevent neurological damage and to improve outcome. In addition, despite wide distribution of highly developed and professional emergency medical systems in western industrialized countries, survival chances of patients with uncontrolled traumatic haemorrhagic shock in the prehospital setting are still poor.

SUMMARY

A multicenter, randomized, controlled, international clinical trial is being initiated to assess the effects of arginine vasopressin (10 IU) vs. saline placebo in prehospital traumatic haemorrhagic shock patients, not responding to standard shock treatment, being managed by helicopter emergency medical services [vasopressin in traumatic haemorrhagic shock (VITRIS.at) study].

Vasopressin in pediatric shock and cardiac arrest

OBJECTIVE

To review the physiology and the published literature on the role of vasopressin in shock in children.

DATA SOURCE

We searched MEDLINE (1966-2007), EMBASE (1980-2007), and the Cochrane Library, using the terms vasopressin, terlipressin, and shock and synonyms or related terms for relevant studies in pediatrics. We searched the online ISRCTN-Current Controlled Trials registry for ongoing trials. We reviewed the reference lists of all identified studies and reviews as well as personal files to identify other published studies.

RESULTS

Beneficial effects have been reported in vasodilatory shock and asystolic cardiac arrest in adults. Solid evidence for vasopressin use in children is scant. Observational studies have reported an improvement in blood pressure and rapid weaning off catecholamines during administration of low-dose vasopressin. Dosing in children is extrapolated from adult studies.

CONCLUSIONS

Vasopressin offers promise in shock and cardiac arrest in children. However, in view of the limited experience with vasopressin, it should be used with caution. Results of a double-blind, randomized controlled trial in children with vasodilatory shock will be available soon.

Medication-related complications in the trauma patient

Trauma patients are twice as likely to have adverse reactions to medication as nontrauma patients. The need for medication in trauma patients is high. Surgery is often necessary, and immunosuppression and hypercoagulability may be present. Adverse drug events can be caused in part by altered pharmacokinetics, drug interactions, and polypharmacy. Medications may also have serious long-term adverse effects, which must be considered. It is not the purpose of this review article to discuss all adverse effects of all medications. This article will discuss the more common adverse effects of medications for trauma patients in the acute care setting, in the following categories: pain control, sedation, antibiotics, seizure prophylaxis in head trauma, atrial fibrillation, deep vein thrombosis and pulmonary embolism prophylaxis, hemodynamic support, adrenal insufficiency, factor VIIa.

Copeptin: clinical use of a new biomarker

Arginine vasopressin (AVP) is a key hormone in the human body. Despite the clinical relevance of AVP in maintaining fluid balance and vascular tone, measurement of mature AVP is difficult and subject to preanalytical errors. Recently, copeptin, a 39-amino acid glycopeptide that comprises the C-terminal part of the AVP precursor (CT-proAVP), was found to be a stable and sensitive surrogate marker for AVP release, analogous to C-peptide for insulin. Copeptin measurement has been shown to be useful in various clinical indications, including the diagnosis of diabetes insipidus and the monitoring of sepsis and cardiovascular diseases. Here we review recent findings regarding the relationship between AVP and copeptin, and affirm the value of AVP as a surrogate marker for AVP.

[Vasopressin as a rescue vasopressor agent. Treatment of selected cardiogenic shock states]

Vasodilatory shock is the most common form of shock in the critically ill patient. As a consequence of overwhelming and prolonged mediator production, vasodilatory shock can be the common final pathway of primary non-vasodilatory shock (e.g. cardiogenic or hypovolemic shock). A supplementary infusion of arginine vasopressin (AVP) showed beneficial effects on hemodynamics and potentially on the outcome in patients with vasodilatory shock due to sepsis or after major surgery. In this case series, successful administration of AVP in three surgical patients with primary cardiogenic shock forms is reported. The hemodynamic effects of AVP were comparable to those AVP-induced alterations described in septic shock and seem to be predominantly mediated by potent vasoconstriction and the facilitated reduction of higher, potentially toxic catecholamine doses. Thus, an AVP-induced decrease in heart rate and pulmonary arterial pressures may be particularly beneficial in patients with impaired cardiac function.

Copeptin, a stable peptide of the arginine vasopressin precursor, is elevated in hemorrhagic and septic shock

Arginine vasopressin (AVP) levels are increased in hemorrhagic and septic shock. Measurement of AVP levels has limitations due to its short half-life and cumbersome detection method. Copeptin is a more stable peptide derived from the same precursor molecule. We evaluated the plasma copeptin concentration in two independent studies: first, in an experimental baboon model of hemorrhagic shock, and second, in a prospective observational study of 101 consecutive critically ill patients at a university hospital. Copeptin was measured with a newly developed sandwich immunoassay using two polyclonal antibodies to the C-terminal region (amino acid sequence 132-164) of pre-pro-AVP. Copeptin concentrations in hemorrhagic shock increased markedly from median (range) of 7.5 [2.7-13) to 269 pM (241-456 pM). After reperfusion, copeptin levels dropped within hours to a plateau of 27 pM (15-78 pM). In the critically ill patient cohort, copeptin values increased significantly with the severity of the disease and were in patients without sepsis [27.6 pM [2.3-297 pM]), in sepsis [50.0 pM [8.5-268 pM]), in severe sepsis [73.6 pM [15.3-317 pM]), and in septic shock [171.5 pM (35.1-504 pM] compared with 4.1 pM (1.0-13.8 pM) in healthy controls (P for all vs. controls <0.001). On admission, circulating copeptin levels were higher in nonsurvivors (171.5 pM, 46.5-504.0 pM) as compared with survivors (86.8 pM, 8.5-386.0 pM; P = 0.01). Copeptin levels correlated with basal cortisol levels (r = 0.42; P < 0.001) and osmolality (r = 0.42; P < 0.001). In a logistic regression model including other covariates besides copeptin (e.g., determinants of fluid status) on survival, serum copeptin levels were the only independent significant predictor of outcome (P = 0.03). Copeptin concentrations are elevated in hemorrhagic and septic shock. Copeptin was higher on admission in nonsurvivors as compared with survivors, suggesting copeptin as a prognostic marker in sepsis. The availability of a reliable assay for the measurement of AVP release can also prove useful for the assessment of fluid and osmosis status in various diseases.

Arginine vasopressin as a supplementary vasopressor in refractory hypertensive, hypervolemic, hemodilutional therapy in subarachnoid hemorrhage

INTRODUCTION

Hypertensive, hypervolemic, and hemodilutional (HHH) therapy for vasospasm in subarachnoid hemorrhage (SAH) refractory to phenylephrine requires high doses of catecholamines, leading to adverse adrenergic effects. Arginine vasopressin (AVP) has been shown to stabilize advanced shock states while facilitating reduction of catecholamine doses, but its use has never been reported in SAH. In this retrospective study, we investigated the hemodynamic effects and feasibility of supplementary AVP in refractory HHH therapy in SAH.

METHODS

Hemodynamic response (mean arterial pressure [MAP], heart rate, central venous pressure, cardiac index, systemic vascular resistance index, and end diastolic volume index) to a supplementary AVP infusion (0.01-0.04 IU/minute) was recorded within the first 24 hours in 22 patients. Secondary endpoints (serum sodium concentration, incidence of vasospasm, and intracranial pressure [ICP]) were compared to controls on HHH therapy with phenylephrine alone.

RESULTS

After initiation of AVP, MAP increased significantly compared to baseline. Phenylephrine doses decreased significantly, whereas other hemodynamic parameters remained stable. Serum sodium concentrations decreased similarly in both groups (-5 +/- 7 mmol/L versus -6 +/- 4 mmol/L; p = 0.25). No detrimental effects on vasospasm incidence or ICP and cerebral perfusion pressure were noted.

CONCLUSION

AVP may be considered as an alternative supplementary vasopressor in refractory HHH therapy with phenylephrine in SAH. Although we did not observe any deleterious effect of AVP on cerebral circulation, close observation for development of cerebral vasospasm should be undertaken, until it is clearly demonstrated that AVP has no adverse effects on regional cerebral blood flow and symptomatic cerebral vasospasm. Our limited data suggest that low-dose AVP does not cause brain edema, but further study is merited.

Microcirculatory function monitoring at the bedside--a view from the intensive care

Microcirculatory dysfunction plays a key role in the pathophysiology of various disease states and may consequently impact patient outcome. Until recently, the evaluation of the microcirculation using different measurement techniques has been mostly limited to animal and human research. With technical advances, microcirculatory monitoring nowadays becomes more and more available for application in clinical praxis. Unfortunately, measurements within the microcirculation are mostly limited to easily accessible surfaces, such as skin, muscle and tongue. Due to major differences in the physiologic regulation of microcirculatory blood flow and in metabolism between organs and even within different tissues in one organ, the clinical importance of regional microcirculatory measurements remains to be determined. In addition, technical methods available demonstrate large differences in the measured parameters and sampling volume, making interpretation of data even more difficult. Nonetheless, the monitoring of the microcirculation may, ahead of time, alert physicians that tissue oxygen supply becomes compromised and it may lead to a better understanding of basic pathophysiological aspects of disease. In the present review, we describe available non-invasive microcirculatory measurement techniques which can be applied clinically at the bedside. After a short discussion of physiologic and pathophysiologic basics related to microcirculatory monitoring, the measuring principles, applications, strengths and limitations of different monitoring systems are discussed.

VASOPRESSIN MEDIATES THE PRESSOR EFFECT OF HYPERTONIC SALINE SOLUTION IN ENDOTOXIC SHOCK

The administration of lipopolysaccharide (LPS) to experimental animals results in a septic shock-like syndrome characterized by hypotension, and the hemodynamic management includes the restoration of adequate tissue perfusion by administration of resuscitation fluids to achieve an effective circulating volume. In the present study, we sought to investigate the effects of hypertonic saline solution administration on vasopressin secretion and mean arterial pressure in endotoxic shock. The pressor response to isotonic saline solution (0.9% sodium chloride) or hypertonic saline (7.5% sodium chloride, 4 mL/kg i.v.) was evaluated 4 h after LPS (1.5 mg/kg) administration. At this moment, plasma vasopressin did not differ from control; however, the blood pressure was lower in the LPS-treated group. The hypertonic saline administration was followed by an immediate recovery of blood pressure and also by an increase in plasma vasopressin levels compared with isotonic saline solution. The vasopressin V1 receptor antagonist (10 microg/kg, i.v., 5 min before infusion) blocked the pressor response to hypertonic saline solution. These data suggest that the recovery of blood pressure after hypertonic saline solution administration during endotoxic shock is mediated by vasopressin secretion.

Effect of arginine vasopressin on vascular reactivity and calcium sensitivity after hemorrhagic shock in rats and its relationship to Rho-kinase

BACKGROUND

Our previous study showed that vascular smooth muscle was desensitized to calcium after hemorrhagic shock, which is associated with the development of vascular hyporeactivity. Arginine vasopressin (AVP) can constrict blood vessels by the activation of Rho-kinase and had a beneficial effect on endotoxic and hemorrhagic shock. The present study investigated the effects of AVP on vascular reactivity and calcium sensitivity after hemorrhagic shock in rats and its relations with Rho-kinase.

METHODS

Experiments were conducted in vivo and in vitro. In vivo, anesthetized Wistar rats were hemorrhaged to and maintained at a mean arterial pressure (MAP) of 30 mm Hg for 2 hours. The effect of AVP (0.1 and 0.4 U/kg) on the pressor effect of norepinephrine (NE, 3 microg/kg) and contractile response of the superior mesenteric artery (SMA) to NE were observed. In vitro, SMA from hemorrhaged rats was used to evaluate the effects of AVP on vascular reactivity and calcium sensitivity and its relationship with Rho-kinase. Vascular reactivity was determined by observing the contractile response of the SMA to NE and calcium sensitivity was determined by observing the contractile response of the SMA to Ca2+ under depolarizing conditions (120 mmol/L K+).

RESULTS

In vivo NE-induced pressor response and contraction of the SMA after hemorrhagic shock were significantly decreased. AVP (0.4 U/kg) significantly increased the pressor response of NE and the contractile response of the SMA to NE. In vitro, the contractile response of SMA to NE and Ca after hemorrhagic shock was significantly decreased as compared with the control group. AVP pretreatment significantly increased the contractile response of SMA to NE and Ca2+ and made the cumulative dose-response curve of NE and Ca2+ shift to the left. HA-1077, the Rho-kinase antagonist, prevented AVP-induced leftward shift of the dose-response curve of NE and Ca2+.

CONCLUSIONS

AVP can increase the vascular reactivity and calcium sensitivity of SMA in hemorrhagic shock rats. Action of AVP appears to be regulated through a Rho-kinase signaling pathway.

Pharmacologic Support of the Failing Heart

Cardiovascular failure in critically ill patients carries a high mortality. Identification and treatment of the underlying etiology simultaneously with prompt therapy are indicated to avoid the consequences of prolonged shock. Physicians should assess patients using all available clinical, radiologic, and laboratory data to avoid the pitfalls associated with use of single measures of regional or global perfusion. Continued evidence of inadequate perfusion despite fluid resuscitation warrants consideration of placement of a pulmonary artery catheter or pharmacologic support of the cardiovascular system. Finally, the dynamic nature of physiology in critically ill patients requires constant patient reassessment and flexibility in treatment to tailor therapy individually as the pathologic state evolves.