Characteristics of patients receiving vasopressors

Comparative Predictive Accuracies of the Simplified Mortality Score for the Intensive Care Unit, Sepsis Severity Score, and Standard Severity Scores for 90-day Mortality in Sepsis Patients

Background

The standard severity scores were used for predicting hospital mortality of intensive care unit (ICU) patients. Recently, the new predictive score, Simplified Mortality Score for the ICU (SMS-ICU), was developed for predicting 90-day mortality.

Objective

To validate the ability of the SMS-ICU and compare with sepsis severity score (SSS) and original severity scores for predicting 90-day mortality in sepsis patients.

Method

An analysis of retrospective data was conducted in the ICU of a university teaching hospital. Also, 90-day mortality was used for the primary outcome.

Results

A total of 1,161 patients with sepsis were included. The 90-day mortality was 42.4%. The SMS-ICU presented the area under the receiver operating characteristic curve (AUROC) of 0.71, whereas the SSS had significantly higher AUROC than that of the SMS-ICU (AUROC 0.876, p < 0.001). The acute physiology and chronic health evaluation (APACHE) II and IV, and the simplified acute physiology scores (SAPS) II demonstrated good discrimination, with an AUROC above 0.90. The SMS-ICU provides poor calibration for 90-day mortality prediction, similar to the SSS and other standard severity scores. Furthermore, 90-day mortality was underestimated by the SMS-ICU, which had a standardized mortality ratio (SMR) of 1.36. The overall performance by Brier score demonstrated that the SMS-ICU was inferior to the SSS (0.222 and 0.169, respectively). Also, SAPS II presented the best overall performance with a Brier score of 0.092.

Conclusion

The SMS-ICU indicated lower performance compared to the SSS, standard severity scores. Consequently, modifications are required to enhance the performance of the SMS-ICU.

How to cite this article

Sathaporn N, Khwannimit B. Comparative Predictive Accuracies of the Simplified Mortality Score for the Intensive Care Unit, Sepsis Severity Score, and Standard Severity Scores for 90-day Mortality in Sepsis Patients. Indian J Crit Care Med 2024;28(4):343-348.

Protocol Compliance Guiding Angiotensin II Use in Post Cardiovascular Surgery Vasoplegia

Catecholamines and vasopressin are commonly used in patients with post cardiovascular surgery vasoplegia (PCSV). Multimodal therapy, including methylene blue (MB), hydroxocobalamin, and angiotensin II (Ang II), may improve outcomes in patients who remain hypotensive despite catecholamine and vasopressin therapy. However, a standardized approach has not been established. We created a protocol at Emory Healthcare (Emory Protocol), which provides guidance on norepinephrine equivalent dose (NED) and the use of noncatecholamines in the setting of PCSV and sought to determine the clinical significance of adherence to the protocol.

Intensive care patients receiving vasoactive medications: A retrospective cohort study

BACKGROUND

Vasoactive medications are high-risk drugs commonly used in intensive care units (ICUs), which have wide variations in clinical management.

OBJECTIVES

The aim of this study was to describe the patient population, treatment, and clinical characteristics of patients who did and did not receive vasoactive medications while in the ICU and to develop a predictive tool to identify patients needing vasoactive medications.

METHODS

A retrospective cohort study of patients admitted to a level three tertiary referral ICU over a 12-month period from October 2018 to September 2019 was undertaken. Data from electronic medical records were analysed to describe patient characteristics in an adult ICU. Chi square and Mann-Whitney U tests were used to analyse data relating to patients who did and did not receive vasoactive medications. Univariate analysis and Pearson's r² were used to determine inclusion in multivariable logistic regression.

RESULTS

Of 1276 patients in the cohort, 40% (512/1276) received a vasoactive medication for haemodynamic support, with 84% (428/512) receiving noradrenaline. Older patients (odds ratio [OR] = 1.02; 95% confidence interval [CI] = 1.01-1.02; p < 0.001) with higher Acute Physiology and Chronic Health Evaluation (APACHE) III scores (OR = 1.04; 95% CI = 1.03-1.04; p < 0.001) were more likely to receive vasoactive medications than those not treated with vasoactive medications during an intensive care admission. A model developed using multivariable analysis predicted that patients admitted with sepsis (OR = 2.43; 95% CI = 1.43-4.12; p = 0.001) or shock (OR = 4.05; 95% CI = 2.68-6.10; p < 0.001) and managed on mechanical ventilation (OR = 3.76; 95% CI = 2.81-5.02; p < 0.001) were more likely to receive vasoactive medications.

CONCLUSIONS

Mechanically ventilated patients admitted to intensive care for sepsis and shock with higher APACHE III scores were more likely to receive vasoactive medications. Predictors identified in the multivariable model can be used to direct resources to patients most at risk of receiving vasoactive medications.

Interpretability of time-series deep learning models: A study in cardiovascular patients admitted to Intensive care unit

Interpretability is fundamental in healthcare problems and the lack of it in deep learning models is currently the major barrier in the usage of such powerful algorithms in the field. The study describes the implementation of an attention layer for Long Short-Term Memory (LSTM) neural network that provides a useful picture on the influence of the several input variables included in the model. A cohort of 10,616 patients with cardiovascular diseases is selected from the MIMIC III dataset, an openly available database of electronic health records (EHRs) including all patients admitted to an ICU at Boston's Medical Centre. For each patient, we consider a 10-length sequence of 1-hour windows in which 48 clinical parameters are extracted to predict the occurrence of death in the next 7 days. Inspired from the recent developments in the field of attention mechanisms for sequential data, we implement a recurrent neural network with LSTM cells incorporating an attention mechanism to identify features driving model's decisions over time. The performance of the LSTM model, measured in terms of AUC, is 0.790 (SD = 0.015). Regard our primary objective, i.e. model interpretability, we investigate the role of attention weights. We find good correspondence with driving predictors of a transparent model (r = 0.611, 95% CI [0.395, 0.763]). Moreover, most influential features identified at the cohort-level emerge as known risk factors in the clinical context. Despite the limitations of study dataset, this work brings further evidence of the potential of attention mechanisms in making deep learning model more interpretable and suggests the application of this strategy for the sequential analysis of EHRs.

Associations between peripheral perfusion disorders, mean arterial pressure and dose of norepinephrine administrated in the early phase of septic shock

The aim of the study was to explore the correlations between peripheral perfusion, mean arterial pressure and the dose-rate of norepinephrine (NE) infused for the treatment of septic shock. The study is retrospective analysis of data acquired prospectively on 57 patients during the first 24 hours after the occurrence of the shock. Clinical and haemodynamic characteristics, skin perfusion parameters (capillary refill time [CRT], mottling score and temperature gradients) and the dose rate of NE infusion were collected. Negative correlations between mean arterial pressure (MAP) and temperature gradients (core-to-toe: P = .03, core-to-index: P = .04) were found and abnormal CRT was associated with lower MAP (P = .02). The dose rate of NE was negatively correlated with temperature gradients (core-to-toe: P = .02, core-to-index: P = .01, forearm-to-index: P = .008) in the overall population. In patients receiving NE for at least 12 hours, the NE dose rate positively was correlated with the mottling score (P = .006), temperature gradients (core-to-toe: P = .04, forearm-to-index: P = .02, core-to-index: P = .005) and CRT (P = .001). The dose of NE administrated was associated with 14-days mortality (odds ration [OR] = 1.21 [1.06-1.38], P = .006) and with 28-days mortality (OR = 1.17 [1.01-1.36], P = 0.04). In conclusion, the study described the presence of correlations between peripheral perfusion and MAP and between peripheral perfusion and the dose rate of NE infusion.

Hitting the Vasopressor Ceiling: Finding Norepinephrine Associated Mortality in the Critically Ill

BACKGROUND

There is no consensus on what dose of norepinephrine corresponds with futility. The purpose of this study was to investigate the maximum infusion and cumulative doses of norepinephrine associated with survival for patients in medical and surgical intensive care units (MICU and SICU).

MATERIALS AND METHODS

A retrospective review was conducted of 661 critically ill patients admitted to a large academic medical center who received norepinephrine. Univariate, multivariate, and area under the curve analyses with optimal cut offs for maximum infusion rate and cumulative dosage were determined by Youden Index.

RESULTS

The population was 54.9% male, 75.8% white, and 58.7 ± 16.1 y old with 384 (69.8%) admitted to the MICU and 166 (30.2%) admitted to the SICU, including 38 trauma patients. Inflection points in mortality were seen at 18 mcg/min and 17.6 mg. The inflection point was higher in MICU patients at 21 mcg/min and lower in SICU patients at 11 mcg/min. MICU patients also had a higher maximum cumulative dosage of 30.7 mg, compared to 2.7 mg in SICU patients. In trauma patients, norepinephrine infusions up to 5 mcg/min were associated with a 41.7% mortality rate.

CONCLUSION

A maximum rate of 18 mcg/min and cumulative dose of 17.6 mg were the inflection points for mortality risk in ICU patients, with SICU patients tolerating lower doses. In trauma patients, even low doses of norepinephrine were associated with higher mortality. These data suggest that MICU, SICU, and trauma patients differ in need for, response to, and outcome from escalating norepinephrine doses.

A time-sensitive analysis of the prognostic utility of vasopressor dose in septic shock

It is unclear whether the association between vasopressor dose and mortality is affected by duration of administration. We examined whether prognostication in septic shock is feasible through the use of daily median vasopressor doses. We undertook a single-centre retrospective cohort study. We included patients with a diagnosis of septic shock admitted to the intensive care unit at Queen Elizabeth Hospital, Birmingham, UK, between April 2016 and July 2019. The primary outcome measure was 90-day mortality. We defined vasopressor dose as the median norepinephrine equivalent dose (equivalent infusion rates of all vasopressors and inotropes) recorded for each day, for the first four days of septic shock. We divided patients into groups by vasopressor dose quintiles and calculated their 90-day mortality rate. We examined area under the receiver operator characteristic curves for prognostic ability. In total, 844 patients were admitted with septic shock and had a 90-day mortality of 43% (n = 358). Over the first four days, median vasopressor dose decreased in 93% of survivors and increased in 56% of non-survivors. The mortality rate associated with a given vasopressor dose quintile increased on sequential days of septic shock. The area under the receiver operator characteristic curves of daily median vasopressor dose against mortality increased from day 1 to day 4 (0.67 vs. 0.86, p < 0.0001). By day 4, a median daily vasopressor dose > 0.05 μg.kg^-1 .min^-1 had an 80% sensitivity and specificity for mortality. The prognostic utility of vasopressor dose improved considerably with shock duration. Prolonged administration of small vasopressor doses was associated with a high attributable mortality.

High-Dose Vasopressor Therapy for Pediatric Septic Shock: When Is Too Much?

It is unknown if the requirement for high dose of vasopressor (HDV) represents a poor outcome in pediatric septic shock. This is a retrospective observational analysis with data obtained from a single center. We evaluated the association between the use of HDV and survival in these patients. A total of 62 children (38 survivors and 24 nonsurvivors) were assessed. The dose of vasopressor (hazard ratio 2.06) and oliguria (hazard ratio 3.17) was independently associated with mortality. The peak of vasopressor was the best prognostic predictor. A cutoff of 1.3 μg/kg/min was associated with mortality with a sensitivity of 75% and specificity of 89%. Vasopressor administration higher than 1.3 μg/kg/min was associated with increased mortality in children with septic shock.

Effect of Very Low-Dose Hydrocortisone on Shock Reversal in Patients With Septic Shock

Supplemental Digital Content is available in the text.

In patients with septic shock, hydrocortisone 200–400 mg/d has been shown to reverse shock compared with placebo. Lower doses of hydrocortisone have not previously been studied, and there are no previous studies comparing two different doses of hydrocortisone. At our institution, some clinicians routinely prescribe doses less than 200 mg/d. This study aims to compare the effect of lower doses of hydrocortisone to standard doses on shock reversal and adverse events in septic shock.

Pharmacologic Agents for the Treatment of Vasodilatory Shock

Vasodilatory shock is a life-threatening syndrome in critically ill patients and is characterized by severe hypotension and resultant tissue hypoperfusion. This shock state requires the use of vasopressor agents to restore adequate vascular tone. Norepinephrine is still recommended as first-line vasopressor in the management of critically ill patients suffering from severe vasodilation. In the recent time, catecholaminergic vasopressor drugs have been associated with possible side effects at higher dosages. This so-called catecholamine toxicity has focused on alternative noncatecholaminergic vasopressors or the use of moderate doses of multiple vasopressors with complementary mechanisms of action. Besides vasopressin and terlipressin, angiotensin II may be a promising drug for the management of vasodilatory shock. In addition, adjunctive drugs, such as hydrocortisone, methylene blue or ascorbic acid can be added to conventional vasopressor therapy. The objective of this review is to give an overview of the current available vasopressor agents used in vasodilatory shock. A thorough search of PubMed was conducted in order to identify the majority of studies related to the subject. Data on the outcome of several drugs and future perspective of possible management strategies for the therapy of vasodilatory shock are discussed.

Modulation of Peroxynitrite Reduces Norepinephrine Requirements in Ovine MRSA Septic Shock

Vascular hypo-responsiveness to vasopressors during septic shock is a challenging problem. This study is to test the hypothesis that reactive nitrogen species (RNS), such as peroxynitrite, are major contributing factors to vascular hypo-responsiveness in septic shock. We hypothesized that adjunct therapy with peroxynitrite decomposition catalyst (PDC) would reduce norepinephrine requirements in sepsis resuscitation. Fourteen female Merino sheep were subjected to a "two-hit" injury (smoke inhalation and endobronchial instillation of live methicillin-resistant Staphylococcus aureus [1.6-2.5 × 10 CFUs]). The animals were randomly allocated to control: injured, fluid resuscitated, and titrated norepinephrine, n = 7; or PDC: injured, fluid resuscitated, titrated norepinephrine, and treated with PDC, n = 7. One-hour postinjury, an intravenous injection of PDC (0.1 mg/kg) was followed by a continuous infusion (0.04 mg/kg/h). Titration of norepinephrine started at 0.05 mcg/kg/min based on their mean arterial pressure. All animals were mechanically ventilated and monitored in the conscious state for 24 h. The mean arterial pressure was well maintained in the PDC with significantly less norepinephrine requirement from 7 to 23 h after injury compared with control. Total norepinephrine dose, the highest norepinephrine rate, and time on norepinephrine support were also significantly lower in PDC. Modified sheep organ failure assessment scores at 6 to 18 h postinjury were significantly lower in PDC compared with control. PDC improved survival rate at 24 h (71.4% vs. 28.6%). PDC treatment had no adverse effects. In conclusion, the modulation of RNS may be considered an effective adjunct therapy for septic shock, in the case of hypo-responsiveness to norepinephrine.

Factors associated with outcomes of septic shock patients receiving high dose noradrenaline according to three primary infection sites

OBJECTIVE

To identify factors associated with outcome of septic shock patients receiving high dose noradrenaline according to three primary infection sites.

METHODS

This retrospective study was based on data from a publicly available ICU database (Medical Information Mart for Intensive Care [MIMIC] III. Septic shock patients receiving high dose (≥1 μg/kg per min) noradrenaline and ≥18 years were identified and their characteristics and outcomes were compared according to three primary infection sites (abdominal, respiratory and urinary tract).

RESULTS

154 septic shock patients who received high doses of noradrenaline were identified; (89 [58%] had a respiratory infection, 41 [27%] an abdominal infection and 24 [16%] a urinary infection). There were no differences among the three infection groups in duration/maximum dosage of noradrenaline, length of stay in the ICU/hospital, do not resuscitate (DNR) rates, hypertension and adequate antimicrobial therapy. Patients with urinary infections had a lower risk of death at 28-days compared with those with abdominal or respiratory infections.

CONCLUSIONS

The prognosis for septic shock patients receiving high dose noradrenaline is poor. Patients with abdominal or respiratory infections are at higher risk of death compared with those with urinary infections.

Peroxynitrite decomposition catalyst reduces vasopressin requirement in ovine MRSA sepsis

Background

Sepsis is one of the most frequent causes of death in the intensive care unit. Host vascular hypo-responsiveness to vasopressors during septic shock is one of the challenging problems. This study tested the hypothesis that adjunct therapy with peroxynitrite decomposition catalyst (WW-85) would reduce arginine vasopressin (AVP) requirements during sepsis resuscitation, using ovine sepsis model.

Methods

Thirteen adult female Merino sheep, previously instrumented with multiple vascular catheters, were subjected to “two-hit” (cotton smoke inhalation and intrapulmonary instillation of live methicillin-resistant Staphylococcus aureus; 3.5 × 10¹¹ colony-forming units) injury. Post injury, animals were awakened and randomly allocated to the following groups: (1) AVP: injured, fluid resuscitated, and titrated with AVP, n = 6 or (2) WW-85 + AVP: injured, fluid resuscitated, treated with WW-85, and titrated with AVP, n = 7. One-hour post injury, a bolus intravenous injection of WW-85 (0.1 mg/kg) was followed by a 23-h continuous infusion (0.02 mg/kg/h). Titration of AVP started at a dose of 0.01 unit/min, when mean arterial pressure (MAP) decreased by 10 mmHg from baseline, despite aggressive fluid resuscitation, and the rate was further adjusted to maintain MAP. After the injury, all animals were placed on a mechanical ventilator and monitored in the conscious state for 24 h.

Results

The injury induced severe hypotension refractory to aggressive fluid resuscitation. High doses of AVP were required to partially attenuate the sepsis-induced hypotension. However, the cumulative AVP requirement was significantly reduced by adjunct treatment with WW-85 at 17–24 h after the injury (p < 0.05). Total AVP dose and the highest AVP rate were significantly lower in the WW-85 + AVP group compared to the AVP group (p = 0.02 and 0.04, respectively). Treatment with WW-85 had no adverse effects. In addition, the in vitro effects of AVP on isolated artery diameter changes were abolished with peroxynitrite co-incubation.

Conclusions

The modulation of reactive nitrogen species, such as peroxynitrite, may be considered as a novel adjunct treatment option for septic shock associated with vascular hypo-responsiveness to vasopressors.

Infections with Carbapenem-Resistant Gram-Negative Bacteria are a Serious Problem Among Critically Ill Children: A Single-Centre Retrospective Study

Children in paediatric intensive care units (PICUs) are vulnerable to infections because invasive devices are frequently used during their admission. We aimed to determine the prevalence, associated factors, and prognosis of infections in our PICU. This retrospective study evaluated culture results from 477 paediatric patients who were treated in the PICU between January 2014 and March 2019. Ninety patients (18.9%) had bacterial infections, with gram-negative bacteria being the predominant infectious agents. Culture-positive patients were younger than culture-negative patients, and age was related to mortality and various clinical factors. Culture-positive bacterial infections in the PICU were associated with increased use of invasive mechanical ventilation (odds ratio(OR); 2.254), red blood cell (RBC) transfusions (OR:2.624), and inotropic drugs (OR:2.262). Carbapenem resistance was found in approximately one-third of gram-negative bacteria, and was most common in tracheal aspirate specimens and cases involving Klebsiella spp. Total parenteral nutrition was a significant risk factor (OR:5.870). Positive blood culture results were associated with poorer patient survival than other culture results. These findings indicate that infections, especially those involving carbapenem-resistant bacteria, are an important issue when treating critically ill children.

Angiotensin II in Vasodilatory Shock

The Angiotensin II for the Treatment of Vasodilatory Shock (ATHOS-3) trial demonstrated the vasopressor effects and catecholamine-sparing properties of angiotensin II. As a result, the Food and Drug Administration has approved angiotensin II for the treatment of vasodilatory shock. This review details the goals of treatment of vasodilatory shock in addition to the history, current use, and recent research regarding the use of angiotensin II. An illustrative case of the use of angiotensin II is also incorporated for understanding the clinical utility of the drug.

Regional differences in the treatment of refractory vasodilatory shock using Angiotensin II in High Output Shock (ATHOS-3) data

INTRODUCTION

Despite international guidelines, regional differences in treatment of vasodilatory shock remain. We characterized these differences using data from Angiotensin II in High Output Shock (ATHOS-3) trial.

METHODS

The 321 patients treated in the ATHOS-3 trial were included. Baseline and hour-48 data were analyzed for differences in demographics, clinical characteristics, and treatment patterns, and grouped into four geographical areas: United States, Canada, Europe, and Australasia. Differences were analyzed by Kruskal-Wallis tests for continuous, and chi-square tests for categorical data. Temporal analysis compared changes in the treatment of shock during the treatment period.

RESULTS

Differences in baseline characteristics across geographic areas were noted in BMI, albumin, CVP, MELD score, APACHE II score, and total SOFA score. Baseline norepinephrine and norepinephrine equivalent doses (NED) were higher (p < .0001 and p = .0494, respectively), and vasopressin use was lower (p < .0001) in Europe. Baseline steroids were utilized more in the US and Canada (p = .0011).

CONCLUSIONS

Management of vasodilatory shock differs globally with respect to utilization of steroids and vasopressors. This practice heterogeneity may influence shock trials interpretation and patient outcomes, though more definitive evidence would require larger prospective intervention data.

Angiotensin II: a new therapeutic option for vasodilatory shock

Angiotensin II (Ang II), part of the renin-angiotensin-aldosterone system (RAS), is a potent vasoconstrictor and has been recently approved for use by the US Food and Drug Administration in high-output shock. Though not a new drug, the recently published Angiotensin II for the Treatment of High Output Shock (ATHOS-3) trial, as well as a number of retrospective analyses have sparked renewed interest in the use of Ang II, which may have a role in treating refractory shock. We describe refractory shock, the unique mechanism of action of Ang II, RAS dysregulation in shock, and the evidence supporting the use of Ang II to restore blood pressure. Evidence suggests that Ang II may preferentially be of benefit in acute kidney injury and acute respiratory distress syndrome, where the RAS is known to be disrupted. Additionally, there may be a role for Ang II in cardiogenic shock, angiotensin converting enzyme inhibitor overdose, cardiac arrest, liver failure, and in settings of extracorporeal circulation.

Acute Kidney Injury After Subarachnoid Hemorrhage

BACKGROUND

Acute kidney injury (AKI) is common in critically ill patients and may contribute to poor outcome. Few data are available on the incidence and impact of AKI in patients suffering from nontraumatic subarachnoid hemorrhage (SAH).

METHODS

We reviewed all patients admitted to our Department of Intensive Care with SAH over a 3-year period. Exclusion criteria were time from SAH symptoms to intensive care unit (ICU) admission >96 hours and ICU stay <48 hours. AKI was defined as sustained oligoanuria (urine output <0.5 mL/kg/h for 24 h) or an increase in plasma creatinine (≥0.3 mg/dL or a 1.5-fold increase from baseline level within 48 h). Neurological status was assessed at day 28 using the Glasgow Outcome Scale (GOS) (from 1=death to 5=good recovery; favorable outcome=GOS 4 to 5).

RESULTS

Of 243 patients admitted for SAH during the study period, 202 met the inclusion/exclusion criteria (median age 56 y, 78 male). Twenty-five patients (12%) developed AKI, a median of 8 (4 to 10) days after admission. Independent predictors of AKI were development of clinical vasospasm, and treatment with vancomycin. AKI was more frequent in ICU nonsurvivors than in survivors (11/50 vs. 14/152, P=0.03), and in patients with an unfavorable neurological outcome than in other patients (17/93 vs. 8/109, P=0.03). Nevertheless, in multivariable regression analysis, AKI was not an independent predictor of outcome.

CONCLUSIONS

AKI occurred in >10% of patients after SAH. These patients had more severe neurological impairment and needed more aggressive ICU therapy; AKI did not significantly influence outcome.

Outcome of patients with septic shock and high-dose vasopressor therapy

Background

Despite the dissemination of international guidelines, mortality from septic shock remains high. Norepinephrine is recommended as first-line vasopressor therapy with a target mean arterial pressure of 65 mmHg. High-dose vasopressor (HDV) may also be required. This study aimed to assess survival in patients with septic shock requiring HDV. We conducted a retrospective study of patients admitted between January 2008 and December 2013 to a 13-bed ICU for septic shock and receiving high-dose vasopressor therapy (defined by a dose >1 µg/kg/min). Primary outcome was 28-day mortality (D28). Secondary outcomes were 90-day mortality (D90), organ failure score (SOFA), duration of organ failure, duration and dosage of vasopressor agent and ischemic complications.

Results

In our cohort of 106 patients, mortality reached 60.4% at D28 and 66.3% at D90. One in two patients died before D10. The weight-based mean dose of vasopressor (WMD) represented the best prognostic factor. Using a cutoff of 0.75 µg/kg/min, WMD was associated with mortality with a sensitivity of 73% and specificity of 74%. The mortality rate reached 86.4% when WMD was above the cutoff value and associated with a SOFA score >10. Digital or limb necrosis was documented in 6 patients (5.7%).

Conclusions

In total, 40% of septic shock patients receiving high-dose vasopressor therapy survived at day 28 after admission. A WMD cutoff value of 0.75 µg/kg/min, associated with a >10 SOFA score, was a strong predictor of death. These results provide insights into outcome of refractory septic shock, showing that administration of high-dose vasopressor may indeed be useful in these patients.

Misdirected Sympathy: The Role of Sympatholysis in Sepsis and Septic Shock

The spectrum of sepsis and septic shock remains a highly prevalent disease state, carrying a high risk of morbidity and mortality. The sympathetic nervous system (SNS) plays an important role in this initial cascade, enabling the host to respond to invading pathogens; however, prolonged activation can become pathological. The potential for unregulated sympathetic tone to become of detriment in patients with sepsis has fueled interest in the role and impact of sympatholysis, the selective inhibition of sympathetic tone. The cornerstone of septic shock therapy for decades has been the supplementation of catecholamines and thus potential further perpetuation of this sympathetic dysregulation. Although the theory of sympatholysis circulates around cardiovascular effects and stroke volume optimization, the impact of augmenting the SNS may extend well beyond this, including the impacts on the immune system, inflammatory cascade, and even gene transcription. Presently, the most robust clinical evidence involves the use of the cardioselective β-blocker esmolol in patients with septic shock with persistent tachycardia secondary to catecholamine use. Evidence is isolated only to animal models with α-agonists. Future evidence stands to elucidate the balance of sympathetic and autonomic tone as well as the potential role of redirecting and maximizing sympathetic activity.

Efficacy and Outcomes After Vasopressin Guideline Implementation in Septic Shock

BACKGROUND

In septic shock, the dose of norepinephrine (NE) at which vasopressin (AVP) should be added is unknown. Following an increase in AVP price, our medical intensive care unit (MICU) revised its vasopressor guidelines to reserve AVP for patients requiring greater than 50 µg/min of NE.

OBJECTIVE

The purpose of this study is to compare efficacy and safety outcomes for patients admitted before the guideline revision with those for patients admitted after the revision.

METHODS

This was a single-center, retrospective cohort study of patients admitted to Vanderbilt University Medical Center from November 1, 2014, to November 30, 2015. Before June 1, 2015, the vasopressor guidelines recommended initiation of AVP for patients requiring 10 µg/min of NE or greater. After June 1, 2015, the guidelines recommended initiation of AVP at a NE dose of 50 µg/min or greater.

RESULTS

Time to achieve goal mean arterial pressure (MAP) was shorter in the postintervention group (2.0 vs 1.3 hours; P = 0.03) in univariate analysis but not after adjusting for prespecified confounders. Incidence of new arrhythmias was similar between the 2 groups (14.9% vs 10.9%; P = 0.567). In multivariable analysis accounting for baseline severity of illness, admission after the revision was associated with decreased 28-day mortality (odds ratio = 0.34; 95% CI = 0.16-0.71; P = 0.004).

CONCLUSIONS

Use of a vasopressor guideline restricting AVP initiation in septic patients to those on at least 50 µg/min of NE appeared to be safe and did not affect the time to reach goal MAP.

Should the norepinephrine maximal dosage rate be greatly increased in late shock?

Any advanced shock eventually degenerates into vasoplegia, which responds weakly to vasopressors. The highest reported norepinephrine flow rate is 3 μg/kg/min. We present the case of a young explosion victim, who was transferred in late haemorrhagic shock. Apart from usual treatment (hydration, mass transfusion protocol), single-agent norepinephrine was used to maintain a mean arterial pressure (MAP) of >60-65 mm Hg. For several hours, norepinephrine flow was 7-10 times the aforementioned (highest reported) in order to achieve our goal; during which, further hydration or transfusion would not contribute to MAP elevation. Sequential Organ Failure Assessment (SOFA) severity score was 18 (expected mortality >99%). The patient survived without underperfusion-related damage. We conclude that norepinephrine dosages could potentially be greatly increased in late shock. We must resist giving up flow escalation based on its numerical value.

Catecholamine use is associated with enterocyte damage in critically ill patients

Small bowel damage is frequent but underdiagnosed among critically ill patients with shock. High catecholamine doses may have a deleterious effect on mesenteric blood flow. Plasma intestinal fatty acid-binding protein (I-FABP) concentration is a marker of enterocyte damage, whereas plasma citrulline concentration is a marker of functional enterocyte mass. We hypothesized that high doses of catecholamines in critically ill patients may be associated with enterocyte damage. This study aimed to determine the link between catecholamine use and dose with enterocyte damage. This is a prospective observational study performed in a large regional university teaching hospital. Critically ill patients requiring epinephrine and/or norepinephrine at admission to a medical intensive care unit (ICU) were included, as well as controls not receiving catecholamines. We evaluated at admission plasma I-FABP and citrulline concentrations, abdominal perfusion pressure (APP), and variables relating to prognosis and treatment. Patients were categorized according to the quartiles of catecholamine dose at ICU admission. Sixty critically ill patients receiving catecholamines and 27 not receiving catecholamines were included. Plasma I-FABP was higher among patients receiving catecholamine than in controls. Among patients receiving catecholamines, a dose of 0.48 γ kg min or more at ICU admission was associated with a higher I-FABP concentration. A Sepsis-related Organ Failure Assessment score higher than 11 and plasma I-FABP more than 524 pg mL at ICU admission were independently associated with 28-day mortality (odds ratio, 4.0 [1.24-12.95] and odds ratio, 4.90 [1.44-16.6], respectively). Catecholamine use is associated with I-FABP elevation in critically ill patients. Critically ill patients receiving more than 0.48 γ kg min of epinephrine and/or norepinephrine at ICU admission have high I-FABP concentrations. This suggests that enterocyte damage reflects the severity of shock, and an adverse effect of catecholamines per se is possible.

Prognosis of patients with shock receiving vasopressors

BACKGROUND

Consensus guidelines suggested that both dopamine and norepinephrine may be used, but specific doses are not recommended. The aim of this study is to determine the predictive role of vasopressors in patients with shock in intensive care unit.

METHODS

One hundred and twenty-two patients, who had received vasopressors for 1 hour or more in intensive care unit (ICU) between October 2008 and October 2011, were included. There were 85 men and 37 women, with a median age of 65 years (55-73 years). Their clinical data were retrospectively collected and analyzed.

RESULTS

The median simplified acute physiological score 3 (SAPS 3) was 50 (42-55). Multivariate analysis showed that septic shock (P=0.018, relative risk: 4.094; 95% confidential interval: 1.274-13.156), SAPS 3 score at ICU admission (P=0.028, relative risk: 1.079; 95% confidential interval: 1.008-1.155), and norepinephrine administration (P<0.001, relative risk: 9.353; 95% confidential interval: 2.667-32.807) were independent predictors of ICU death. Receiver operating characteristic curve analysis demonstrated that administration of norepinephrine ≥0.7 μg/kg per minute resulted in a sensitivity of 75.9% and a specificity of 90.3% for the likelihood of ICU death. In patients who received norepinephrine ≥0.7 μg/kg per minute there was more ICU death (71.4% vs. 44.8%) and in-hospital death (76.2% vs. 48.3%) than in those who received norepinephrine <0.7 μg/kg per minute. These patients had also a decreased 510-day survival rate compared with those who received norepinephrine <0.7 μg/kg per minute (19.2% vs. 64.2%).

CONCLUSION

Septic shock, SAPS 3 score at ICU admission, and norepinephrine administration were independent predictors of ICU death for patients with shock. Patients who received norepinephrine ≥0.7 μg/kg per minute had an increased ICU mortality, an increased in-hospital mortality, and a decreased 510-day survival rate.

Therapeutic strategies for high-dose vasopressor-dependent shock

There is no consensual definition of refractory shock. The use of more than 0.5 mcg/kg/min of norepinephrine or epinephrine to maintain target blood pressure is often used in clinical trials as a threshold. Nearly 6% of critically ill patients will develop refractory shock, which accounts for 18% of deaths in intensive care unit. Mortality rates are usually greater than 50%. The assessment of fluid responsiveness and cardiac function can help to guide therapy, and inotropes may be used if hypoperfusion signs persist after initial resuscitation. Arginine vasopressin is frequently used in refractory shock, although definite evidence to support this practice is still missing. Its associations with corticosteroids improved outcome in observational studies and are therefore promising alternatives. Other rescue therapies such as terlipressin, methylene blue, and high-volume isovolemic hemofiltration await more evidence before use in routine practice.

Survival after shock requiring high-dose vasopressor therapy

BACKGROUND

Some patients with hypotensive shock do not respond to usual doses of vasopressor therapy. Very little is known about outcomes after high-dose vasopressor therapy (HDV). We sought to characterize survival among patients with shock requiring HDV. We also evaluated the possible utility of stress-dose corticosteroid therapy in these patients.

METHODS

We conducted a retrospective study of patients with shock requiring HDV in the ICUs of five hospitals from 2005 through 2010. We defined HDV as receipt at any point of ≥ 1 μg/kg/min of norepinephrine equivalent (calculated by summing norepinephrine-equivalent infusion rates of all vasopressors). We report survival 90 days after hospital admission. We evaluated receipt of stress-dose corticosteroids, cause of shock, receipt of CPR, and withdrawal or withholding of life support therapy.

RESULTS

We identified 443 patients meeting inclusion criteria. Seventy-six (17%) survived. Survival was similar (20%) among the 241 patients with septic shock. Among the 367 nonsurvivors, 254 (69%) experienced withholding/withdrawal of care, and 115 (31%) underwent CPR. Stress-dose corticosteroid therapy was associated with increased survival (P = .01).

CONCLUSIONS

One in six patients with shock survived to 90 days after HDV. The majority of nonsurvivors died after withdrawal or withholding of life support therapy. A minority of patients underwent CPR. Additionally, stress-dose corticosteroid therapy appears reasonable in patients with shock requiring HDV.

High-dose norepinephrine treatment: determinants of mortality and futility in critically ill patients

BACKGROUND

Critically ill patients with circulatory shock sometimes need rescue treatment with high doses of norepinephrine, a treatment that may be associated with a poor outcome because of excessive vasoconstriction.

OBJECTIVE

To evaluate the outcome of treatment and its determinants in patients with circulatory shock who received high doses of norepinephrine in the intensive care unit and to identify indicators of futility for the treatment.

METHODS

A retrospective study was done on 113 consecutive patients with circulatory shock who received 0.9 μg/kg per minute or greater of norepinephrine during at least 1 hour at any time in the intensive care unit. Data were extracted from the electronic patient data management system according to a predefined checklist.

RESULTS

A total of 39 patients survived for 28 days after admission to the intensive care unit. The variables independently associated with 28-day mortality in multivariable models included low urine flow, high lactate levels, high organ failure score, high prothrombin time, and need for epinephrine cotreatment. The reason, dose, and duration of norepinephrine administration did not have prognostic significance. Scores greater than 40 on the Acute Physiology and Chronic Health Evaluation II, bicarbonate levels less than 9.0 mEq/L, or receipt of an epinephrine dose of 0.25 μg/kg per minute or greater were associated with 100% mortality.

CONCLUSIONS

Although the cause of shock and treatment with norepinephrine were not predictive of death when high doses of the drug were deemed necessary, rescue treatment with high-dose norepinephrine is futile in patients with severe disease and metabolic acidemia.