Should we target blood pressure in sepsis?:

Risk factors for the development of sepsis in patients with cirrhosis in intensive care units

Sepsis is a serious complication of liver cirrhosis. This study aimed to develop a risk prediction model for sepsis among patients with liver cirrhosis. A total of 3130 patients with liver cirrhosis were enrolled from the Medical Information Mart for Intensive Care IV database, and randomly assigned into training and validation cohorts in a 7:3 ratio. The least absolute shrinkage and selection operator (LASSO) regression was used to filter variables and select predictor variables. Multivariate logistic regression was used to establish the prediction model. Based on LASSO and multivariate logistic regression, gender, base excess, bicarbonate, white blood cells, potassium, fibrinogen, systolic blood pressure, mechanical ventilation, and vasopressor use were identified as independent risk variables, and then a nomogram was constructed and validated. The consistency index (C-index), receiver operating characteristic curve, calibration curve, and decision curve analysis (DCA) were used to measure the predictive performance of the nomogram. As a result of the nomogram, good discrimination was achieved, with C-indexes of 0.814 and 0.828 for the training and validation cohorts, respectively, and an area under the curve of 0.849 in the training cohort and 0.821 in the validation cohort. The calibration curves demonstrated good agreement between the predictions and observations. The DCA curves showed the nomogram had significant clinical value. We developed and validated a risk-prediction model for sepsis in patients with liver cirrhosis. This model can assist clinicians in the early detection and prevention of sepsis in patients with liver cirrhosis.

Fluids and vasopressors in septic shock: basic knowledge for a first approach in the emergency department

Much research, both pathophysiological and clinical, has been produced about septic shock during the last 20 years. Nevertheless, many aspects of treatment are still controversial, among these the approach to the administration of fluids and vasopressors. After the first clinical trial on Early goal-directed therapy (EGDT) was published, a liberal approach to the use of fluids and conservative use of vasopressors prevailed, but in recent years a more restrictive use of fluids and an earlier introduction of vasopressors seem to be preferred. Although both treatments are based on sound pathophysiological knowledge,  clinical evidence is still inadequate and somehow controversial.  In this non-systematic review, recent research on the hemodynamics of septic shock and its treatment with fluids and inotropes is discussed. As a conclusion, general indications are proposed for a practical approach to patients in septic shock.

Applicability of Vasopressor Trials in Adult Critical Care: A Prospective Multicentre Meta-Epidemiologic Cohort Study

Objective

To assess the applicability of evidence from landmark randomized controlled trials (RCTs) of vasopressor treatment in critically ill adults.

Study Design and Setting

This prospective, multi-center cohort study was conducted at five medical and surgical intensive care units at three tertiary care centers. Consecutive cases of newly initiated vasopressor treatment were included. The primary end point was the proportion of patients (≥18 years) who met the eligibility criteria of 25 RCTs of vasopressor therapy in critically ill adults included in the most recent Cochrane review. Multilevel Poisson regression was used to estimate the eligibility proportions with 95% confidence intervals for each trial. Secondary end points included the eligibility criteria that contributed most to trial ineligibility, and the relationship between eligibility proportions and (i) the Pragmatic-Explanatory Continuum Indicator Summary-2 (PRECIS-2) score, and (ii) the recruitment-to-screening ratio of each RCT. The PRECIS-2 score was used to assess the degree of pragmatism of each trial.

Results

Between January 1, 2017, and January 1, 2019, a total of 1189 cases of newly initiated vasopressor therapy were included. The median proportion of cases meeting eligibility criteria for all 25 RCTs ranged from 1.3% to 6.0%. The eligibility criteria contributing most to trial ineligibility were the exceedance of a specific norepinephrine dose, the presence of a particular shock type, and the drop below a particular blood pressure value. Eligibility proportions increased with the PRECIS-2 score but not with the recruitment-to-screening ratio of the trials.

Conclusion

The applicability of evidence from available trials on vasopressor treatment in critically ill adults to patients receiving vasopressors in daily practice is limited. Applicability increases with the degree of study pragmatism but is not reflected in a high recruitment-to-screening ratio. Our findings may help researchers design vasopressor trials and promote standardized assessment and reporting of the degree of pragmatism achieved.

Pulse pressure during the initial resuscitative period in patients with septic shock treated with a protocol-driven resuscitation bundle therapy

BACKGROUND/AIMS

Maintaining a mean arterial pressure (MAP) ≥ 65 mmHg during septic shock should be based on individual circumstances, but specific target is poorly understood. We investigated associations between time-weighted average (TWA) hemodynamic parameters during the initial resuscitative period and 28-day mortality.

METHODS

Prospectively collected data were obtained from a septic shock patient registry, according to the Sepsis-3 definition, between 2016 and 2018. The TWA systolic blood pressure, diastolic blood pressure, MAP, shock index, and pulse pressure (PP) during the first 6 hours after shock recognition were compared. Multivariable regression analysis was performed to assess associations between these parameters and 28-day mortality.

RESULTS

Of 340 patients with septic shock, 92 died. Only the median TWA PP differed between the survivors and non-survivors (39.2 mmHg vs. 43.0 mmHg, p = 0.020), whereas the other indexes did not. When PP was divided into quartiles (< 34, 34 to 40, 40 to 48, and > 48 mmHg), the mortality rate was higher in the highest quartile (41.2%). Multivariable logistic analysis revealed that PP (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.012 to 1.622; p = 0.039) and PP of > 48 mmHg (OR, 2.25; 95% CI, 1.272 to 3.981; p = 0.005) were independently associated with 28-day mortality.

CONCLUSION

PP was significantly associated with 28-day mortality in patients with septic shock and MAP maintained at > 65 mmHg during the first 6 hours. Further studies are warranted to optimize strategies for maintaining PP and MAP at > 65 mmHg during the early resuscitative period.

Automated Blood Pressure Control

Arterial pressure management is a crucial task in the operating room and intensive care unit. In high-risk surgical and in critically ill patients, sustained hypotension is managed with continuous infusion of vasopressor agents, which most commonly have direct α agonist activity like phenylephrine or norepinephrine. The current standard of care to guide vasopressor infusion is manual titration to an arterial pressure target range. This approach may be improved by using automated systems that titrate vasopressor infusions to maintain a target pressure. In this article, we review the evidence behind blood pressure management in the operating room and intensive care unit and discuss current and potential future applications of automated blood pressure control.

Central venous pressure value can assist in adjusting norepinephrine dosage after the initial resuscitation of septic shock

BACKGROUND

New definitions for sepsis and septic shock (Sepsis-3) were published, but the strategy to adjust vasopressors after the initial guidelines is still unclear. We conducted a retrospective observational study to explore dosing strategy of norepinephrine (NE).

METHODS

A retrospective observational study in the 15-bed mixed intensive care unit of a tertiary care university hospital. The study was performed on septic shock patients after 30 mL/kg fluid resuscitation and mean arterial pressure (MAP) levels reached >65 mmHg requiring NE. We divided patients into NE dosage increase and decrease groups, and collected hemodynamic and tissue perfusion parameters before (T1) and after (T2) adjusting NE dosage.

RESULTS

In both NE increase and decrease groups, central venous pressure (CVP) and pressure difference between usual MAP and MAP (dMAP) at the T1 time point were associated with lactate clearance. In groups LC HM (CVP <10 mmHg, dMAP > 0 mmHg) and HC HM (CVP ≥ 10 mmHg, dMAP > 0 mmHg), decrease in NE dosage decreased lactate level, while in group HC LM (CVP ≥ 10 mmHg, dMAP ≤ 0 mmHg), both increase and decrease in NE dosage led to increase lactate level.

CONCLUSIONS

After patients with septic shock (Sepsis-3) resuscitated to reach the initial recovery target goals, combination of CVP and MAP refer to usual levels can help doctors make the next decision to make the correct choice of increase NE dosage or decrease NE dosage.

Elevated Plasma Histone H4 Levels Are an Important Risk Factor in the Development of Septic Cardiomyopathy

Background:

Myocardial impairment is a major complication and an important prognostic predictor of sepsis. Therefore, early and accurate diagnosis as well as timely management of septic cardiomyopathy is critical to achieve favorable outcomes.

Aims:

To investigate the risk factors of septic cardiomyopathy.

Study Design:

Cross-sectional study.

Methods:

This study performed between May 2016 and June 2018 recruited 93 septic patients from the intensive care unit. All patients received standardized treatments. Septic patients were divided into two groups: non cardiomyopathy (n=45) and septic cardiomyopathy group (n=48). Blood samples were collected and transthoracic echocardiography was performed within 24 hours of intensive care unit admission. Septic patients with one ultrasound abnormality but no history of heart disease were diagnosed as having septic cardiomyopathy. Plasma histones, cardiac troponin I, and N-terminal pro-brain natriuretic peptide were measured using ELISA. Sequential Organ Failure Assessment scores, vasopressor use, and the outcomes of intensive care unit stay were analyzed. Spearman rank analysis was used to determine the correlation between plasma histone H4 and other parameters. Binary logistic regression and receiver operating characteristic curve analysis were used to determine the risk factors for septic cardiomyopathy.

Results:

Compared with the non-cardiomyopathy group, the septic cardiomyopathy group had significantly higher plasma H4 and cardiac troponin I levels, a higher Sequential Organ Failure Assessment score, more frequent vasopressor use, and a higher mortality rate (p<0.05). Plasma histone H4 levels positively correlated with cardiac troponin I (r=0.577, p<0.001), N-terminal pro-brain natriuretic peptide (r=0.349, p=0.001), and Sequential Organ Failure Assessment scores (r=0.469, p<0.001). Binary logistic regression and receiver operating characteristic curve analyses revealed that elevated plasma histone H4 levels and vasopressor use were important risk factors for septic cardiomyopathy (p<0.05).

Conclusion:

Elevated plasma histone H4 levels could be used to predict septic cardiomyopathy in patients with sepsis.

Closed-loop vasopressor control: in-silico study of robustness against pharmacodynamic variability

Initial feasibility of a novel closed-loop controller created by our group for closed-loop control of vasopressor infusions has been previously described. In clinical practice, vasopressor potency may be affected by a variety of factors including other pharmacologic agents, organ dysfunction, and vasoplegic states. The purpose of this study was therefore to evaluate the effectiveness of our controller in the face of large variations in drug potency, where 'effective' was defined as convergence on target pressure over time. We hypothesized that the controller would remain effective in the face up to a tenfold variability in drug response. To perform the robustness study, our physiologic simulator was used to create randomized simulated septic patients. 250 simulated patients were managed by the closed-loop in each of 7 norepinephrine responsiveness conditions: 0.1 ×, 0.2 ×, 0.5 ×, 1 ×, 2 ×, 5 ×, and 10 × expected population response to drug dose. Controller performance was evaluated for each level of norepinephrine response using Varvel's criteria as well as time-out-of-target. Median performance error and median absolute performance error were less than 5% in all response levels. Wobble was below 3% and divergence remained negative (i.e. the controller tended to converge towards the target over time) in all norepinephrine response levels, but at the highest response level of 10 × the value approached zero, suggesting the controller may be approaching instability. Response levels of 0.1 × and 0.2 × exhibited significantly higher time-out-of-target in the lower ranges (p < 0.001) compared to the 1 × response level as the controller was slower to correct the initial hypotension. In this simulation study, the closed-loop vasopressor controller remained effective in simulated patients exhibiting 0.1 to 10 × the expected population drug response.

Baroreflex Sensitivity and Blood Pressure Variability can Help in Understanding the Different Response to Therapy During Acute Phase of Septic Shock

BACKGROUND

Mean values of hemodynamic variables are poorly effective in evaluating an actual recovery of the short-term autonomic mechanisms for blood pressure (BP) and heart rate (HR) regulation. The aim of this work is to analyze the response to therapy in the early phase of septic shock to verify possible associations between BP recovery and BP autonomic control.

METHODS

This is an ancillary study from the multicenter prospective observational trial Shockomics (NCT02141607). A total of 21 septic shock patients were studied at two time points during the acute phase of shock and were classified according to changes in SOFA score. Time series of BP components and HR were analyzed in time and frequency domain. Baroreflex sensitivity (BRS) was assessed, and a mathematical model for the decomposition of diastolic arterial pressure (DAP) oscillations was used to understand the different contributions of BRS and HR on peripheral vascular resistance control.

RESULTS

Only those patients, who significantly improved organ function (responders, R), showed an increase of mean value and low frequency (LF) power in BP time series. Fluid accumulation was higher in the non-responders (NR). BRS increased in NR and the model of DAP variability showed that the contribution of HR was highly reduced in NR.

CONCLUSIONS

Although patients reached the mean BP target of 65 mmHg, our analyses highlighted important differences in terms of autonomic nervous system control. BP variability, HR variability and baroreflex trends can add information to individual vital sign measure such as mean BP, and can help in understanding the responsiveness to the combination of symphatomimetic drugs and fluid therapy.

A dual boundary classifier for predicting acute hypotensive episodes in critical care

An Acute Hypotensive Episode (AHE) is the sudden onset of a sustained period of low blood pressure and is one among the most critical conditions in Intensive Care Units (ICU). Without timely medical care, it can lead to an irreversible organ damage and death. By identifying patients at risk for AHE early, adequate medical intervention can save lives and improve patient outcomes. In this paper, we design a novel dual–boundary classification based approach for identifying patients at risk for AHE. Our algorithm uses only simple summary statistics of past Blood Pressure measurements and can be used in an online environment facilitating real–time updates and prediction. We perform extensive experiments with more than 4,500 patient records and demonstrate that our method outperforms the previous best approaches of AHE prediction. Our method can identify AHE patients two hours in advance of the onset, giving sufficient time for appropriate clinical intervention with nearly 80% sensitivity and at 95% specificity, thus having very few false positives.

Muscle membrane properties in A pig sepsis model: Effect of norepinephrine

INTRODUCTION

Sepsis-induced myopathy and critical illness myopathy are common causes of muscle weakness in intensive care patients. This study investigated the effect of different mean arterial blood pressure (MAP) levels on muscle membrane properties following experimental sepsis.

METHODS

Sepsis was induced with fecal peritonitis in 12 of 18 anesthetized and mechanically ventilated pigs. Seven were treated with a high (75-85 mmHg) and 5 were treated with a low (≥60 mmHg) MAP target for resuscitation. In septic animals, resuscitation was started 12 h after peritonitis induction, and muscle velocity recovery cycles were recorded 30 h later.

RESULTS

Muscles in the sepsis/high MAP group showed an increased relative refractory period and reduced early supernormality compared with the remaining septic animals and the control group, indicating membrane depolarization and/or sodium channel inactivation. The membrane abnormalities correlated positively with norepinephrine dose.

DISCUSSION

Norepinephrine may contribute to sepsis-induced abnormalities in muscle by impairing microcirculation. Muscle Nerve 57: 808-813, 2018.

Feasibility of automated titration of vasopressor infusions using a novel closed-loop controller

Blood pressure management is a central concern in critical care patients. For a variety of reasons, titration of vasopressor infusions may be an ideal use-case for computer assistance. Using our previous experience gained in the bench-to-bedside development of a computer-assisted fluid management system, we have developed a novel controller for this purpose. The aim of this preliminary study was to assess the feasibility of using this controller in simulated patients to maintain a target blood pressure in both stable and variable blood-pressure scenarios. We tested the controller in two sets of simulation scenarios: one with stable underlying blood pressure and a second with variable underlying blood pressure. In addition, in the variable phase of the study, we tested infusion-line delays of 8-60 s. The primary outcome for both testing conditions (stable and variable) was % case time in target range. We determined a priori that acceptable performance on the first phase of the protocol would require greater than 95% case-time in-target given the simple nature of the protocol, and for the second phase of the study 80% or greater given the erratic nature of the blood pressure changes taking place. 250 distinct cases for each simulation condition, both managed and unmanaged, were run over 4 days. In the stable hemodynamic conditions, the unmanaged group had an MAP of 57.5 ± 4.6 mmHg and spent only 5.6% of case time in-target. The managed group had an MAP of 70.3 ± 2.6 and spent a total of 99.5% of case time in-target (p < 0.00001 for both comparisons between groups). In the variable hemodynamic conditions, the unmanaged group had an MAP of 53.1 ± 5.0 mmHg and spent 0% of case time in-target. The managed group had an MAP of 70.5 ± 3.2 mmHg (p < 0.00001 compared to unmanaged group) and spent 88.6% of case time in-target (p < 0.00001 compared to unmanaged group), with 6.4% of case time over and 5.1% of case time under target. Increasing infusion lag increased coefficient of variation by about 10% per 15 s of lag (p = 0.001). This study demonstrated that this novel controller for vasopressor administration is able to main a target mean arterial pressure in a simulated physiologic model in the face of random disturbances and infusion-line lag.

Hypotension Risk Prediction via Sequential Contrast Patterns of ICU Blood Pressure

Acute hypotension is a significant risk factor for in-hospital mortality at intensive care units. Prolonged hypotension can cause tissue hypoperfusion, leading to cellular dysfunction and severe injuries to multiple organs. Prompt medical interventions are thus extremely important for dealing with acute hypotensive episodes (AHE). Population level prognostic scoring systems for risk stratification of patients are suboptimal in such scenarios. However, the design of an efficient risk prediction system can significantly help in the identification of critical care patients, who are at risk of developing an AHE within a future time span. Toward this objective, a pattern mining algorithm is employed to extract informative sequential contrast patterns from hemodynamic data, for the prediction of hypotensive episodes. The hypotensive and normotensive patient groups are extracted from the MIMIC-II critical care research database, following an appropriate clinical inclusion criteria. The proposed method consists of a data preprocessing step to convert the blood pressure time series into symbolic sequences, using a symbolic aggregate approximation algorithm. Then, distinguishing subsequences are identified using the sequential contrast mining algorithm. These subsequences are used to predict the occurrence of an AHE in a future time window separated by a user-defined gap interval. Results indicate that the method performs well in terms of the prediction performance as well as in the generation of sequential patterns of clinical significance. Hence, the novelty of sequential patterns is in their usefulness as potential physiological biomarkers for building optimal patient risk stratification systems and for further clinical investigation of interesting patterns in critical care patients.

Bioartificial Therapy of Sepsis: Changes of Norepinephrine-Dosage in Patients and Influence on Dynamic and Cell Based Liver Tests during Extracorporeal Treatments

Purpose. Granulocyte transfusions have been used to treat immune cell dysfunction in sepsis. A granulocyte bioreactor for the extracorporeal treatment of sepsis was tested in a prospective clinical study focusing on the dosage of norepinephrine in patients and influence on dynamic and cell based liver tests during extracorporeal therapies. Methods and Patients. Ten patients with severe sepsis were treated twice within 72 h with the system containing granulocytes from healthy donors. Survival, physiologic parameters, extended hemodynamic measurement, and the indocyanine green plasma disappearance rate (PDR) were monitored. Plasma of patients before and after extracorporeal treatments were tested with a cell based biosensor for analysis of hepatotoxicity. Results. The observed mortality rate was 50% during stay in hospital. During the treatments, the norepinephrine-dosage could be significantly reduced while mean arterial pressure was stable. In the cell based analysis of hepatotoxicity, the viability and function of sensor-cells increased significantly during extracorporeal treatment in all patients and the PDR-values increased significantly between day 1 and day 7 only in survivors. Conclusion. The extracorporeal treatment with donor granulocytes showed promising effects on dosage of norepinephrine in patients, liver cell function, and viability in a cell based biosensor. Further studies with this approach are encouraged.

The association between lactate, mean arterial pressure, central venous oxygen saturation and peripheral temperature and mortality in severe sepsis: a retrospective cohort analysis

Background

During resuscitation in severe sepsis and septic shock, several goals are set. However, usually not all goals are equally met. The aim of this study is to determine the relative importance of the different goals, such as mean arterial pressure (MAP), lactate, central venous oxygen saturation (ScvO₂) and central to forefoot temperature (delta-T), and how they relate to intensive care unit (ICU) and hospital mortality.

Methods

In a retrospective cohort study in a 20-bed mixed medical and surgical ICU of a teaching hospital we studied consecutive critically ill patients who were admitted for confirmed infection and severe sepsis or septic shock between 2008 and 2014. All validated MAP, lactate levels, ScvO₂ and delta-T for the first 24 hours of ICU treatment were extracted from a clinical database. Logistic regression analyses were performed on validated measurements in the first hour after admission and on mean values over 24 hours. Patients were categorized by MAP (24-hour mean below or above 65 mmHg) and lactate (24-hour mean below or above 2 mmol/l) for Cox regression analysis.

Results

From 837 patients, 821 were eligible for analysis. All had MAP and lactate measurements. The delta-T was available in 812 (99 %) and ScvO₂ was available for 193 out of these patients (23.5 %). Admission lactate (p < 0.001) and admission MAP (p < 0.001) were independent predictors of ICU and hospital mortality. The 24-hour mean values for lactate, MAP and delta-T were all independent predictors of ICU mortality. Hospital mortality was independently predicted by the 24-hour mean lactate (odds ratio (OR) 1.34, 95 % confidence interval (CI) 1.30–1.40, p = 0.001) mean MAP (OR 0.96, 95 % CI 0.95–0.97, p = 0.001) and mean delta-T (OR 1.09, 95 % CI 1.06–1.12, p = 0.001). Patients with a 24-hour mean lactate below 2 mmol/l and a 24-hour mean MAP above 65 mmHg had the best survival, followed by patients with a low lactate and a low MAP.

Conclusions

Admission MAP and lactate independently predicted ICU and hospital mortality. The 24-hour mean lactate, mean MAP and mean delta-T independently predicted hospital mortality. A Cox regression analysis showed that 24-hour mean lactate above 2 mmol/l is the strongest predictor for ICU mortality.

Vasopressors for hypotensive shock

BACKGROUND

Initial goal-directed resuscitation for hypotensive shock usually includes administration of intravenous fluids, followed by initiation of vasopressors. Despite obvious immediate effects of vasopressors on haemodynamics, their effect on patient-relevant outcomes remains controversial. This review was published originally in 2004 and was updated in 2011 and again in 2016.

OBJECTIVES

Our objective was to compare the effect of one vasopressor regimen (vasopressor alone, or in combination) versus another vasopressor regimen on mortality in critically ill participants with shock. We further aimed to investigate effects on other patient-relevant outcomes and to assess the influence of bias on the robustness of our effect estimates.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015 Issue 6), MEDLINE, EMBASE, PASCAL BioMed, CINAHL, BIOSIS and PsycINFO (from inception to June 2015). We performed the original search in November 2003. We also asked experts in the field and searched meta-registries to identify ongoing trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing various vasopressor regimens for hypotensive shock.

DATA COLLECTION AND ANALYSIS

Two review authors abstracted data independently. They discussed disagreements between them and resolved differences by consulting with a third review author. We used a random-effects model to combine quantitative data.

MAIN RESULTS

We identified 28 RCTs (3497 participants) with 1773 mortality outcomes. Six different vasopressors, given alone or in combination, were studied in 12 different comparisons.All 28 studies reported mortality outcomes; 12 studies reported length of stay. Investigators reported other morbidity outcomes in a variable and heterogeneous way. No data were available on quality of life nor on anxiety and depression outcomes. We classified 11 studies as having low risk of bias for the primary outcome of mortality; only four studies fulfilled all trial quality criteria.In summary, researchers reported no differences in total mortality in any comparisons of different vasopressors or combinations in any of the pre-defined analyses (evidence quality ranging from high to very low). More arrhythmias were observed in participants treated with dopamine than in those treated with norepinephrine (high-quality evidence). These findings were consistent among the few large studies and among studies with different levels of within-study bias risk.

AUTHORS' CONCLUSIONS

We found no evidence of substantial differences in total mortality between several vasopressors. Dopamine increases the risk of arrhythmia compared with norepinephrine and might increase mortality. Otherwise, evidence of any other differences between any of the six vasopressors examined is insufficient. We identified low risk of bias and high-quality evidence for the comparison of norepinephrine versus dopamine and moderate to very low-quality evidence for all other comparisons, mainly because single comparisons occasionally were based on only a few participants. Increasing evidence indicates that the treatment goals most often employed are of limited clinical value. Our findings suggest that major changes in clinical practice are not needed, but that selection of vasopressors could be better individualised and could be based on clinical variables reflecting hypoperfusion.

What happens to the fluid balance during and after recovering from septic shock?

Objective

We aimed to evaluate the cumulative fluid balance during the period of shock and determine what happens to fluid balance in the 7 days following recovery from shock.

Methods

A prospective and observational study in septic shock patients. Patients with a mean arterial pressure ≥ 65mmHg and lactate < 2.0mEq/L were included < 12 hours after weaning from vasopressor, and this day was considered day 1. The daily fluid balance was registered during and for seven days after recovery from shock. Patients were divided into two groups according to the full cohort’s median cumulative fluid balance during the period of shock: Group 1 ≤ 4.4L (n = 20) and Group 2 > 4.4L (n = 20).

Results

We enrolled 40 patients in the study. On study day 1, the cumulative fluid balance was 1.1 [0.6 - 3.4] L in Group 1 and 9.0 [6.7 - 13.8] L in Group 2. On study day 7, the cumulative fluid balance was 8.0 [4.5 - 12.4] L in Group 1 and 14.7 [12.7 - 20.6] L in Group 2 (p < 0.001 for both). Afterwards, recovery of shock fluid balance continued to increase in both groups. Group 2 had a more prolonged length of stay in the intensive care unit and hospital compared to Group 1.

Conclusion

In conclusion, positive fluid balances are frequently seen in patients with septic shock and may be related to worse outcomes. During the shock period, even though the fluid balance was previously positive, it becomes more positive. After recovery from shock, the fluid balance continues to increase. The group with a more positive fluid balance group spent more time in the intensive care unit and hospital.

The duration of hypotension determines the evolution of bacteremia-induced acute kidney injury in the intensive care unit

Background

Exploration of the impact of severe hypotension on the evolution of acute kidney injury in septic patients.

Methods and Results

We reviewed the hemodynamic parameters of 137 adults with septic shock and proven blood stream infection in the ICU. Severe hypotension was defined as a mean arterial blood pressure (MAP) ≤65 mmHg. The influence of the duration of severe hypotension on the evolution of acute kidney injury was evaluated according to the RIFLE classification, with day 0 defined as the day of a positive blood stream infection. After bloodstream infection, the probability for a patient to be in Failure was significantly higher than before blood stream infection (OR = 1.94, p = 0.0276). Patients have a significantly higher risk of evolving to Failure if the duration of severe hypotension is longer (OR = 1.02 for each 10 minutes increase in duration of a MAP <65 mmHg, p = 0.0472). A cut-off of at least 51 minutes of severe hypotension (<65 mmHg) or at least 5.5 periods of severe hypotension within 1 day identified patients with increased risk to evolve to Failure.

Conclusions

There is a significant influence of both the duration and the number of periods of severe hypotension on the evolution to Failure. Blood stream infection has a significantly negative effect on the relationship between severe hypotension and Failure.

An analytic tool for prediction of hemodynamic responses to vasopressors

This paper presents a new analytic tool for automated control of vasopressor infusion, which uses measured changes in blood pressure to infer changes in the underlying cardiovascular system and then estimate dose-response relationships for the underlying cardinal cardiovascular parameters, i.e., those related to cardiac output (CO) and total peripheral resistance (TPR). Ultimately, blood pressure as a function of vasopressor dose is predicted based on the estimated underlying cardiovascular state by extrapolating the dose-response relationship. As well, this tool adapts to individual subjects with a minimum of individualized training data. In this report, proof-of-principle is provided using experimental epinephrine dose-response data from four different sets of subjects. Given two observations from different infusion rates, the analytic tool was able to accurately predict the groups' blood pressure, heart rate, TPR, stroke volume, and CO as a function of vasopressor dose levels: the root-mean-squared prediction error for the mean arterial pressure (MAP) was consistently smaller than 5% of the underlying MAP; the r(2) values for the TPR, stroke volume, and CO were consistently higher than 0.96; and the limits of agreement between actual versus predicted blood pressure (BP), TPR, stroke volume, and CO were consistently smaller than 8% of the respective underlying values. The proposed analytic tool may provide a meaningful step towards automated control of vasopressor therapy.

Increasing mean arterial blood pressure in sepsis: effects on fluid balance, vasopressor load and renal function

Introduction

The objective of this study was to evaluate the effects of two different mean arterial blood pressure (MAP) targets on needs for resuscitation, organ dysfunction, mitochondrial respiration and inflammatory response in a long-term model of fecal peritonitis.

Methods

Twenty-four anesthetized and mechanically ventilated pigs were randomly assigned (n = 8/group) to a septic control group (septic-CG) without resuscitation until death or one of two groups with resuscitation performed after 12 hours of untreated sepsis for 48 hours, targeting MAP 50-60 mmHg (low-MAP) or 75-85 mmHg (high-MAP).

Results

MAP at the end of resuscitation was 56 ± 13 mmHg (mean ± SD) and 76 ± 17 mmHg respectively, for low-MAP and high-MAP groups. One animal each in high- and low-MAP groups, and all animals in septic-CG died (median survival time: 21.8 hours, inter-quartile range: 16.3-27.5 hours). Norepinephrine was administered to all animals of the high-MAP group (0.38 (0.21-0.56) mcg/kg/min), and to three animals of the low-MAP group (0.00 (0.00-0.25) mcg/kg/min; P = 0.009). The high-MAP group had a more positive fluid balance (3.3 ± 1.0 mL/kg/h vs. 2.3 ± 0.7 mL/kg/h; P = 0.001). Inflammatory markers, skeletal muscle ATP content and hemodynamics other than MAP did not differ between low- and high-MAP groups. The incidence of acute kidney injury (AKI) after 12 hours of untreated sepsis was, respectively for low- and high-MAP groups, 50% (4/8) and 38% (3/8), and in the end of the study 57% (4/7) and 0% (P = 0.026). In septic-CG, maximal isolated skeletal muscle mitochondrial Complex I, State 3 respiration increased from 1357 ± 149 pmol/s/mg to 1822 ± 385 pmol/s/mg, (P = 0.020). In high- and low-MAP groups, permeabilized skeletal muscle fibers Complex IV-state 3 respiration increased during resuscitation (P = 0.003).

Conclusions

The MAP targets during resuscitation did not alter the inflammatory response, nor affected skeletal muscle ATP content and mitochondrial respiration. While targeting a lower MAP was associated with increased incidence of AKI, targeting a higher MAP resulted in increased net positive fluid balance and vasopressor load during resuscitation. The long-term effects of different MAP targets need to be evaluated in further studies.

The cardiopulmonary effects of vasopressin compared with norepinephrine in septic shock

BACKGROUND

Vasopressin is known to be an effective vasopressor in the treatment of septic shock, but uncertainty remains about its effect on other hemodynamic parameters.

METHODS

We examined the cardiopulmonary effects of vasopressin compared with norepinephrine in 779 adult patients with septic shock recruited to the Vasopressin and Septic Shock Trial. More detailed cardiac output data were analyzed for a subset of 241 patients managed with a pulmonary artery catheter, and data were collected for the first 96 h after randomization. We compared the effects of vasopressin vs norepinephrine in all patients and according to severity of shock (< 15 or ≥ 15 μg/min of norepinephrine) and cardiac output at baseline.

RESULTS

Equal BPs were maintained in both treatment groups, with a significant reduction in norepinephrine requirements in the patients treated with vasopressin. The major hemodynamic difference between the two groups was a significant reduction in heart rate in the patients treated with vasopressin (P <.0001), and this was most pronounced in the less severe shock stratum (treatment × shock stratum interaction, P =.03). There were no other major cardiopulmonary differences between treatment groups, including no difference in cardiac index or stroke volume index between patients treated with vasopressin and those treated with norepinephrine. There was significantly greater use of inotropic drugs in the vasopressin group than in the norepinephrine group.

CONCLUSIONS

Vasopressin treatment in septic shock is associated with a significant reduction in heart rate but no change in cardiac output or other measures of perfusion.

TRIAL REGISTRY

ISRCTN Register; No.: ISRCTN94845869; URL: www.isrctn.org

Interrogating a clinical database to study treatment of hypotension in the critically ill

OBJECTIVE

In intensive care, it is imperative to resolve hypotensive episodes (HEs) in a timely manner to minimise end-organ damage. Clinical practice guidelines generally recommend initial treatment with fluid resuscitation followed by vasoactive agent administration if patients remain hypotensive. However, the impact of such interventions on patient outcomes has not been clearly established. Hence, the objective of this study was to investigate the relationship between fluid and vasoactive agent interventions and patient outcomes, while highlighting the utility of electronic medical records in clinical research.

DESIGN

Retrospective cohort study.

SETTING

Intensive care units (ICUs) at a large, academic, tertiary medical center.

PARTICIPANTS

Patients in Multi-parameter Intelligent Monitoring in Intensive Care II (a large electronic ICU database) who experienced a single HE during their ICU stay. 2332 patients had complete data.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome of interest was inhospital mortality. Secondary outcomes were ICU length of stay (LOS), HE duration, Hypotension Severity Index (defined as the mean arterial pressure curve area below 60 mm Hg during the HE) and rise in serum creatinine.

RESULTS

Fluid resuscitation was associated with significantly shorter ICU LOS among ICU survivors (p=0.007). Vasoactive agent administration significantly decreased HE duration (p<0.001) and Hypotension Severity Index (p=0.002) but was associated with increased inhospital mortality risk (p<0.001), prolonged ICU LOS among ICU survivors (p=0.04) and rise in serum creatinine (p=0.002) after adjustment for confounders. Propensity score analyses as well as sensitivity analyses in treatment-, diagnosis- and ICU service-specific subpopulations corroborated the relationship between vasoactive agents and increased inhospital mortality.

CONCLUSIONS

An adverse relationship between vasoactive agents and inhospital mortality was found in patients with hypotension. This study has implications for the care of critically ill patients with hypotension and illustrates the utility of electronic medical records in research when randomised controlled trials are difficult to conduct.

Intensive care of the patient with cirrhosis

Acute deterioration of patients with cirrhosis manifests as multiple organ failure requiring admission to an intensive care unit. Precipitating events may be viral hepatitis, typically in Asia, and drug or alcoholic hepatitis and variceal hemorrhage in the West. Patients with cirrhosis in the intensive care unit have a high mortality, and each admission is associated with a mean charge of US $116,200. Prognosis is determined by the number of organs failing (sequential organ failure assessment [SOFA] score), the presence of infection, and the degree of liver dysfunction (Child-Turcotte-Pugh or Model for End-Stage Liver Disease scores). The most common organ failing is the kidney; sepsis is associated with further deterioration in liver function by compromise of the microcirculation. Care of these critically ill patients with impending multiple organ failure requires a team approach with expertise in both hepatology and critical care. Treatment is aimed at preventing further deterioration in liver function, reversing precipitating factors, and supporting failing organs. Liver transplantation is required in selected patients to improve survival and quality of life. Treatment is futile in some patients, but it is difficult to identify these patients a priori. Artificial and bioartificial liver support systems have thus far not demonstrated significant survival benefit in these patients.