Early prediction of norepinephrine dependency and refractory septic shock with a multimodal approach of vascular failure

Exploration of a nomogram prediction model of 30-day survival in adult ECMO patients

Objective

To investigate the factors of 30-day survival in ECMO patients, establish a nomogram model, and evaluate the predictive value of the model.

Methods

A total of 105 patients with extracorporeal membrane oxygenation (ECMO) were admitted to the Department of Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, from January 2018 to March 2021. Cox regression analysis screened out the risk factors. Based on the results of multivariate analysis, the nomogram model was established by using R software, and the discrimination of the model was verified by bootstrap and calibration.

Results

The results showed that sex, acute physiology and chronic health evaluation (APACHE) II score, disseminated intravascular coagulation (DIC) score before ECMO initiation and average daily dose of norepinephrine were independent risk factors for prognosis. Verify that the nomogram model is verified by bootstrap internally, and the corrected C-index is C-index: 0.886, showing a good degree of discrimination. The calibration curve (calibration) showed that the nomogram model had good agreement. The decision curve analysis(DCA) curve shows good clinical validity above the two extreme curves. Kaplan-Meier curves were drawn for patients in the tertile and compared with the first and second groups. The third group predicted the worst 30-day prognosis for ECMO patients.

Conclusion

The nomogram prediction model constructed based on the sex, APACHE II and DIC score, average daily dose of norepinephrine can effectively screen out the factors affecting the prognosis and provide a reference for individualized treatment of ECMO patients.

Microvascular effects of oxygen and carbon dioxide measured by vascular occlusion test in healthy volunteers

BACKGROUND

Changes in near-infrared spectroscopy-derived regional tissue oxygen saturation (StO₂) during a vascular occlusion test (VOT; ischemic provocation of microcirculation by rapid inflation and deflation of a tourniquet) allow estimating peripheral tissue O₂ consumption (desaturation slope; DS), vascular reactivity (recovery slope; RS) and post-ischemic hyperperfusion (AUC-H). The effects of isolated alterations in the inspiratory fraction of O₂ (FiO₂) and changes in expiratory CO₂ remain to be elucidated. Therefore, in this secondary analysis we determined the effects of standardized isolated instances of hypoxia, hyperoxia, hypocapnia and hypercapnia on the VOT-induced StO₂ changes in healthy volunteers (n = 20) to establish reference values for future physiological studies.

METHODS

StO₂ was measured on the thenar muscle. Multiple VOTs were performed in a standardized manner: i.e. at room air (baseline), during hyperoxia (FiO₂ 1.0), mild hypoxia (FiO₂ ≈ 0.11), and after a second baseline, during hypocapnia (end-tidal CO₂ (etCO₂) 2.5-3.0 vol%) and hypercapnia (etCO₂ 7.0-7.5 vol%) at room air. Differences in DS, RS, and AUC-H were tested using repeated-measures ANOVA.

RESULTS

DS and RS remained constant during all applied conditions. AUC-H after hypoxia was smaller compared to hyperoxia (963 %*sec vs hyperoxia 1702 %*sec, P = 0.005), while there was no difference in AUC-H duration between hypoxia and baseline. The StO₂ peak (after tourniquet deflation) during hypoxia was lower compared to baseline and hyperoxia (92 % vs 94 % and 98 %, P < 0.001).

CONCLUSION

We conclude that in healthy volunteers at rest, common situations observed during anesthesia and intensive care such as exposure to hypoxia, hyperoxia, hypocapnia, or hypercapnia, did not affect peripheral tissue O₂ consumption and vascular reactivity as assessed by VOT-induced changes in StO₂. These observations may serve as reference values for future physiological studies.

TRIAL REGISTRATION

This study represents a secondary analysis of an original study which has been registered at ClinicalTrials.gov nr: NCT02561052.

Dexmedetomidine to reduce vasopressor resistance in refractory septic shock: Protocol for a double-blind randomized controlled pilot trial (ADRESS Pilot study)

Introduction

Refractory septic shock (RSS) is characterized by high vasopressor requirements, as a consequence of vasopressor resistance, which may be caused or enhanced by sympathetic hyperactivation. Experimental models and clinical trials show a reduction in vasopressor requirements and improved microcirculation compared to conventional sedation. Dexmedetomidine did not reduce mortality in clinical trials, but few septic shock patients were enrolled. This pilot trial aims to evaluate vasopressor re-sensitization with dexmedetomidine and assess the effect size, in order to design a larger trial.

Methods

This is an investigator-initiated, multicenter, randomized, double-blind, placebo-controlled trial, comparing dexmedetomidine versus placebo in RSS patients with norepinephrine dose ≥0.5μg/kg/min. The primary outcome is blood pressure response to phenylephrine challenge, 6 hours after completion of a first challenge, after study treatment initiation. Secondary outcomes include feasibility and safety outcomes (bradycardia), mortality, vasopressor requirements, heart rate variability, plasma and urine catecholamines levels. The sample size is estimated at 32 patients to show a 20% improvement in blood pressure response to phenylephrine. Randomization (1:1) will be stratified by center, sedation type and presence of liver cirrhosis. Blood pressure and ECG will be continuously recorded for the first 24 h, enabling high-quality data collection for the primary and secondary endpoints. The study was approved by the ethics committee “Sud-Est VI” (2019-000726-22) and patients will be included after informed consent.

Discussion

The present study will be the first randomized trial to specifically address the hemodynamic effects of dexmedetomidine in patients with septic shock. We implement a high-quality process for data acquisition and recording in the first 24 h, ensuring maximal quality for the evaluation of both efficacy and safety outcomes, as well as transparency of results. The results of the study will be used to elaborate a full-scale randomized controlled trial with mortality as primary outcome in RSS patients.

Trial registration

Registered with ClinicalTrials.gov (NCT03953677). Registered 16 May 2019, https://clinicaltrials.gov/ct2/show/NCT03953677.

Norepinephrine Dosage Is Associated With Lactate Clearance After Resuscitation in Patients With Septic Shock

Background: Some septic shock patients have persistent hyperlactacidemia despite a normal systemic hemodynamics after resuscitation. Central venous oxygen saturation (ScvO₂), mean arterial pressure (MAP), and central venous pressure (CVP) cannot be target in subsequent hemodynamic treatments. Vasoplegia is considered to be one of the main causes of oxygen metabolism abnormalities in septic shock patients, and norepinephrine (NE) is the first-line vasopressor in septic shock treatment; its dosage represents the severity of vasoplegia. This study was performed to determine whether vasoplegia, as assessed by NE dosage, can indicate patients' lactate clearance after the completion of resuscitation.

Methods: A retrospective study was performed, and 106 patients with septic shock in an intensive care unit were analyzed. Laboratory values and hemodynamic variables were obtained upon completion of resuscitation (H 0) and 6 h after (H 6). Lactate clearance was defined as the percent decrease in lactate from H 0 to H 6. Student's t-test, Mann-Whitney U-test, Chi-square or Fisher's exact tests, logistic regression analysis, and receiver operating characteristic (ROC) curve analysis were performed for statistical analysis.

Results: Patients with a mean age of 63.7 ± 13.8 years, baseline APACHE II score of 21.0 ± 5.1, and SOFA score of 12.7 ± 2.7 were enrolled. The study found that after 6-h of resuscitation, lactate clearance (LC) was <10% in 33 patients (31.1%). Patients with 6-h LC <10% compared with 6-h LC ≥ 10% had a higher NE dose (μg·kg⁻¹·min⁻¹) (0.55 [0.36–0.84] vs. 0.25 [0.18–0.41], p < 0.001). Multivariate logistic regression analysis of statistically significant univariate variables showed that NE dose had a significant inverse relationship with 6-h LC < 10%. The cutoff for NE was ≥ 0.32 μg·kg⁻¹·min⁻¹ for predicting 6-h lactate clearance after resuscitation, with a sensitivity of 75.76% and a specificity of 70.00%. Septic shock patients with an NE dose ≥ 0.32 μg·kg⁻¹·min⁻¹, relative to patients with an NE dose < 0.32 μg·kg⁻¹·min⁻¹, had a greater 30-day mortality rate (69.8% vs. 26.4% p < 0.001).

Conclusion: Some patients with septic shock had persistent oxygen metabolism disorders after hemodynamic resuscitation. NE dose may indicate vasoplegia and oxygen metabolism disorder. After resuscitation, septic shock patients with high-dose NE have lower lactate clearance and a greater 30-day mortality rate than those with low-dose NE.

Is the Sympathetic System Detrimental in the Setting of Septic Shock, with Antihypertensive Agents as a Counterintuitive Approach? A Clinical Proposition

Mortality in the setting of septic shock varies between 20% and 100%. Refractory septic shock leads to early circulatory failure and carries the worst prognosis. The pathophysiology is poorly understood despite studies of the microcirculatory defects and the immuno-paralysis. The acute circulatory distress is treated with volume expansion, administration of vasopressors (usually noradrenaline: NA), and inotropes. Ventilation and anti-infectious strategy shall not be discussed here. When circulation is considered, the literature is segregated between interventions directed to the systemic circulation vs. interventions directed to the micro-circulation. Our thesis is that, after stabilization of the acute cardioventilatory distress, the prolonged sympathetic hyperactivity is detrimental in the setting of septic shock. Our hypothesis is that the sympathetic hyperactivity observed in septic shock being normalized towards baseline activity will improve the microcirculation by recoupling the capillaries and the systemic circulation. Therefore, counterintuitively, antihypertensive agents such as beta-blockers or alpha-2 adrenergic agonists (clonidine, dexmedetomidine) are useful. They would reduce the noradrenaline requirements. Adjuncts (vitamins, steroids, NO donors/inhibitors, etc.) proposed to normalize the sepsis-evoked vasodilation are not reviewed. This itemized approach (systemic vs. microcirculation) requires physiological and epidemiological studies to look for reduced mortality.

Pralidoxime improves the hemodynamics and survival of rats with peritonitis-induced sepsis

Several studies have suggested that sympathetic overstimulation causes deleterious effects in septic shock. A previous study suggested that pralidoxime exerted a pressor effect through a mechanism unrelated to the sympathetic nervous system; this effect was buffered by the vasodepressor action of pralidoxime mediated through sympathoinhibition. In this study, we explored the effects of pralidoxime on hemodynamics and survival in rats with peritonitis-induced sepsis. This study consisted of two sub-studies: survival and hemodynamic studies. In the survival study, 66 rats, which survived for 10 hours after cecal ligation and puncture (CLP), randomly received saline placebo, pralidoxime, or norepinephrine treatment and were monitored for up to 24 hours. In the hemodynamic study, 44 rats were randomly assigned to sham, CLP-saline placebo, CLP-pralidoxime, or CLP-norepinephrine groups, and hemodynamic measurements were performed using a conductance catheter placed in the left ventricle. In the survival study, 6 (27.2%), 15 (68.1%), and 5 (22.7%) animals survived the entire 24-hour monitoring period in the saline, pralidoxime, and norepinephrine groups, respectively (log-rank test P = 0.006). In the hemodynamic study, pralidoxime but not norepinephrine increased end-diastolic volume (P <0.001), stroke volume (P = 0.002), cardiac output (P = 0.003), mean arterial pressure (P = 0.041), and stroke work (P <0.001). The pressor effect of norepinephrine was short-lived, such that by 60 minutes after the initiation of norepinephrine infusion, it no longer had any significant effect on mean arterial pressure. In addition, norepinephrine significantly increased heart rate (P <0.001) and the ratio of arterial elastance to ventricular end-systolic elastance (P = 0.010), but pralidoxime did not. In conclusion, pralidoxime improved the hemodynamics and 24-hour survival rate in rats with peritonitis-induced sepsis, but norepinephrine did not.

Effects of a single dose of vitamin D in septic children: a randomized, double-blinded, controlled trial

Objective

To assess the effects of a single dose of vitamin D on 25-hydroxyvitamin D (25OHD) levels and clinical outcomes in children with vitamin D deficiency (VDD) and sepsis.

Methods

In this randomized, controlled trial, eligible children with VDD and sepsis were assigned to receive one dose of 150,000 IU of cholecalciferol or placebo. Serum concentrations of 25OHD, angiotensin-II (Ang-II), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were assessed at baseline and 8 days after treatment. The cardiovascular Sequential Organ Failure Assessment (cv-SOFA) score, septic shock incidence, duration of ventilation, and mortality were also examined.

Results

One hundred nine participants fulfilled the study requirements. The two groups had comparable baseline characteristics. Ang-II, IL-6, and TNF-α concentrations were all reduced after vitamin D supplementation. Furthermore, the cv-SOFA score (1.76 ± 0.8 vs. 2.3 ± 1.1) and incidence of septic shock (7% vs. 20%) were lower in the treatment group than in the control group. The duration of ventilation and mortality rates did not differ between two groups.

Conclusions

A single dose of vitamin D improved 25OHD levels and the incidence of septic shock in children with VDD and sepsis.

Near-Infrared Spectroscopy in Adult Circulatory Shock: A Systematic Review

BACKGROUND

Circulatory shock affects every third patient in intensive care units and is associated with high mortality. Near-infrared spectroscopy (NIRS) could serve as a means for monitoring tissue perfusion in circulatory shock.

PURPOSE

To assess the evidence of NIRS monitoring in circulatory shock, we conducted a systematic review of the literature.

METHODS

The study protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO). We searched PubMed, Ovid MEDLINE, Scopus, and EBM Reviews databases. The reference lists of included articles, last volumes of key journals, and NIRS monitor manufacturers' webpages were searched manually. Two reviewers independently selected included studies. The quality of studies was assessed. The qualitative synthesis was guided by 3 questions: First, does NIRS monitoring improve patient-centered outcomes in adult circulatory shock patient? Second, do NIRS-derived parameters predict patient-centered outcomes, such as mortality and organ dysfunction, and third, does NIRS monitoring give additional information to guide treatment decisions?

MAIN RESULTS

Eighteen observational studies with 927 patients were included. Because of considerable clinical heterogeneity of the data, we were not able to perform a meta-analysis. Also, due to lack of randomized controlled trials, the first review question could not be answered. Based on the current review, baseline tissue oxygen saturation (StO2) however seems to predict mortality and identify patients with most severe forms of circulatory shock.

CONCLUSIONS

Near-infrared spectroscopy-derived StO2 can predict mortality in circulatory shock, but high-quality data on the impact of NIRS monitoring are lacking. Furthermore, the marked heterogeneity of the studies makes combining the results of individual studies difficult. Standardization of methodology and clinical randomized trials are needed before wider clinical use.

Vasopressor Cumulative Dose Requirement and Risk of Early Death During Septic Shock: An Analysis From The EPISS Cohort

Septic shock is the primary cause of death in intensive care units, with about 20% of patients dying in the first 3 days. To design future trials focused on early mortality, we require knowledge of early indicators that can detect patients at high risk of early death from refractory septic shock. The aim of this study was to assess whether the cumulative dose of vasopressors (CDV), calculated as the cumulative dose of epinephrine + norepinephrine, is a predictor of early death (within 72 h) attributable to refractory septic shock (EDASS). This substudy of the EPISS trial was based on 370 patients admitted to a French ICU for septic shock between 2009 and 2011. The area under the receiving operating characteristic curve was calculated for the CDV at 6, 12, 24, 36, and 48 h after vasopressor initiation, and a strategy to predict the risk of EDASS was built based on selected times and thresholds. Among the 370 patients included, 51 (14%) died within the first 72 h with 40 (11%) EDASS. A strategy in two steps (CDV ≥ 800 μg/kg at 6 h and/or CDV ≥ 2,600 μg/kg at 24 h) was able to predict EDASS with sensitivity of 45%, specificity 97%, positive predictive value 78% and negative predictive value 94%. Overall, our results confirm that early death directly attributable to septic shock could be effectively predicted by the CDV in the first hours of treatment. These results will help to select patients eligible for innovative therapies aimed at improving early mortality in septic shock.

Maximum Norepinephrine Dosage Within 24 Hours as an Indicator of Refractory Septic Shock: A Retrospective Study

BACKGROUND

The management of refractory septic shock remains a major challenge in critical care and its early indicators are not fully understood. We hypothesized that the maximum norepinephrine dosage within 24 hours of intensive care unit (ICU) admission may be a useful indicator of early mortality in patients with septic shock.

METHODS

In this retrospective single-center observational study, patients with septic shock admitted to the emergency ICU of an academic medical center between April 2011 and March 2017 were included. Individuals with cardiac arrest and those with do-not-resuscitate orders before admission were excluded. We analyzed if the maximum norepinephrine dosage within 24 hours of ICU admission (MD24) was associated with 7-day mortality.

RESULTS

Among 152 patients with septic shock, 20 (15%) did not survive by day 7. The receiver operating characteristic curve analysis for predicting 7-day mortality revealed a cutoff of MD24 of 0.6 μg/kg/min (sensitivity 47%, specificity 93%). In the multivariable regression analysis, a higher MD24 was significantly associated with 7-day mortality (odds ratio: 7.20; 95% confidence interval [CI]: 2.02-25.7; P = .002) but not with 30-day mortality. Using the inverse probability of treatment weighting method in a propensity scoring analysis, a higher MD24 was significantly associated with 7-day (hazard ratio [HR]: 8.9; 95% CI: 3.2-25.0; P < .001) and 30-day mortality (HR: 2.7; 95% CI: 1.2-5.8; P = .012).

CONCLUSIONS

An MD24 ≥0.6 μg/kg/min was significantly associated with 7-day mortality in patients with septic shock and may therefore be a useful indicator of refractory septic shock.

Timing of administration of epinephrine predicts the responsiveness to epinephrine in norepinephrine-refractory septic shock: a retrospective study

Background

Currently, the appropriate method of management of patients with refractory septic shock remains unclear. This study aimed to evaluate the factors associated with response to epinephrine in norepinephrine-refractory septic shock.

Methods

A retrospective single-center observational study was performed using data from adult patients (≥ 18 years old) admitted to our emergency and medical intensive care unit (ICU) from January 2014 to December 2017 who had received epinephrine to treat norepinephrine-refractory septic shock. The response was considered positive if there was increase in mean arterial pressure of 10 mmHg or decrease in arterial lactate level 3 h after epinephrine administration.

Results

Forty-one patients were included: 24 responders (59%) and 17 non-responders (41%). Responders showed higher rate of survival from shock (92% vs. 18%; P < 0.001), and 28-day survival (83% vs. 18%; P < 0.001). In multivariable analysis, time of epinephrine administration after ICU admission (odds ratio [OR] 0.48; 95% confidence interval [CI] 0.27–0.87; P = 0.011) and SOFA score (OR 0.19; 95% CI 0.04–0.88; P = 0.034) were associated with epinephrine response. Time of epinephrine administration was also significantly associated with survival from shock (OR 0.42; P = 0.005) and 28-day survival (OR 0.14; P = 0.006), while SOFA score did not. Using inverse probability of treatment weighing (IPTW) adjustment of propensity score, epinephrine administration later than 24 h after ICU admission was associated with poor response (OR 0.07; 95% CI 0.02–0.21; P < 0.001).

Conclusions

Early administration of epinephrine after ICU admission (i.e., within 24 h) is associated with better hemodynamic status in patients with refractory septic shock.

Electronic supplementary material

The online version of this article (10.1186/s40560-019-0377-1) contains supplementary material, which is available to authorized users.

Hypothesis: Fever control, a niche for alpha-2 agonists in the setting of septic shock and severe acute respiratory distress syndrome?

During severe septic shock and/or severe acute respiratory distress syndrome (ARDS) patients present with a limited cardio-ventilatory reserve (low cardiac output and blood pressure, low mixed venous saturation, increased lactate, low PaO2/FiO2 ratio, etc.), especially when elderly patients or co-morbidities are considered. Rescue therapies (low dose steroids, adding vasopressin to noradrenaline, proning, almitrine, NO, extracorporeal membrane oxygenation, etc.) are complex. Fever, above 38.5-39.5°C, increases both the ventilatory (high respiratory drive: large tidal volume, high respiratory rate) and the metabolic (increased O2 consumption) demands, further limiting the cardio-ventilatory reserve. Some data (case reports, uncontrolled trial, small randomized prospective trials) suggest that control of elevated body temperature ("fever control") leading to normothermia (35.5-37°C) will lower both the ventilatory and metabolic demands: fever control should simplify critical care management when limited cardio-ventilatory reserve is at stake. Usually fever control is generated by a combination of general anesthesia ("analgo-sedation", light total intravenous anesthesia), antipyretics and cooling. However general anesthesia suppresses spontaneous ventilation, making the management more complex. At variance, alpha-2 agonists (clonidine, dexmedetomidine) administered immediately following tracheal intubation and controlled mandatory ventilation, with prior optimization of volemia and atrio-ventricular conduction, will reduce metabolic demand and facilitate normothermia. Furthermore, after a rigorous control of systemic acidosis, alpha-2 agonists will allow for accelerated emergence without delirium, early spontaneous ventilation, improved cardiac output and micro-circulation, lowered vasopressor requirements and inflammation. Rigorous prospective randomized trials are needed in subsets of patients with a high fever and spiraling toward refractory septic shock and/or presenting with severe ARDS.

Current status of tissue monitoring in the management of shock

PURPOSE OF REVIEW

Tissue monitoring is one of the main strategies at the bedside to guide resuscitation of shock. Advances in tissue monitoring technologies have established noninvasive optical methods and transcutaneous oximetry as modalities of considerable value in the critical care setting for tissue monitoring in shock. The purpose of this article is to highlight the latest developments into the clinical applications of near-infrared spectroscopy, direct visualization of sublingual microcirculation, and transcutaneous oxygen measurements (PtcO2).

RECENT FINDINGS

Near-infrared spectroscopy has been successfully applied in patients with septic shock during vasopressor and blood transfusion therapy to identify patients at high risk for microcirculatory failure. A new generation incident dark field imaging-based handheld microscope has been introduced for quantification of microcirculatory alterations at bedside. Preliminary comparisons with previous versions have shown better quality and superiority of incident dark field in detecting more vessels. PtcO2 measurements have been applied mainly to detect a peripheral low-flow state in circulatory failure using the oxygen challenge test. Altered lung function might have an influence on PtcO2, and thus affect the oxygen challenge test.

SUMMARY

The latest developments of noninvasive optical monitoring and transcutaneous oximetry technologies have helped early identification of septic patients at high risk for microcirculatory failure and could allow more targeted interventions in shock.

Pressor Response to Noradrenaline in the Setting of Septic Shock: Anything New under the Sun-Dexmedetomidine, Clonidine? A Minireview

Progress over the last 50 years has led to a decline in mortality from ≈70% to ≈20% in the best series of patients with septic shock. Nevertheless, refractory septic shock still carries a mortality close to 100%. In the best series, the mortality appears related to multiple organ failure linked to comorbidities and/or an intense inflammatory response: shortening the period that the subject is exposed to circulatory instability may further lower mortality. Treatment aims at reestablishing circulation within a "central" compartment (i.e., brain, heart, and lung) but fails to reestablish a disorganized microcirculation or an adequate response to noradrenaline, the most widely used vasopressor. Indeed, steroids, nitric oxide synthase inhibitors, or donors have not achieved overwhelming acceptance in the setting of septic shock. Counterintuitively, α 2-adrenoceptor agonists were shown to reduce noradrenaline requirements in two cases of human septic shock. This has been replicated in rat and sheep models of sepsis. In addition, some data show that α 2-adrenoceptor agonists lead to an improvement in the microcirculation. Evidence-based documentation of the effects of alpha-2 agonists is needed in the setting of human septic shock.