Interaction Between Fluids and Vasoactive Agents on Mortality in Septic Shock: A Multicenter, Observational Study*

Comparison of Early and Late Norepinephrine Administration in Patients with Septic Shock: A Systematic Review and Meta-analysis

BACKGROUND

Vasopressor administration at an appropriate time is crucial, but the optimal timing remains controversial.

RESEARCH QUESTION

Does early vs late norepinephrine administration impact the prognosis of septic shock?

STUDY DESIGN AND METHODS

Searches were conducted on PubMed, EMBASE, the Cochrane Library, and KMBASE. We included studies of adults with sepsis and categorized patients into an early and late norepinephrine group according to specific time points or differences in norepinephrine use protocols. The primary outcome was overall mortality. The secondary outcomes included length of stay in the ICU, days free from ventilator use, days free from renal replacement therapy, days free from vasopressor use, adverse events, and total fluid volume.

RESULTS

Twelve studies (four randomized controlled trials [RCTs] and eight observational studies) comprising 7,281 patients were analyzed. For overall mortality, no significant difference was found between the early norepinephrine group and late norepinephrine group in RCTs (OR, 0.70; 95% CI, 0.41-1.19) or observational studies (OR, 0.83; 95% CI, 0.54-1.29). In the two RCTs without a restrictive fluid strategy that prioritized vasopressors and lower IV fluid volumes, the early norepinephrine group showed significantly lower mortality than the late norepinephrine group (OR, 0.49; 95%, CI, 0.25-0.96). The early norepinephrine group demonstrated more mechanical ventilator-free days in observational studies (mean difference, 4.06; 95% CI, 2.82-5.30). The incidence of pulmonary edema was lower in the early norepinephrine group in the three RCTs that reported this outcome (OR, 0.43; 95% CI, 0.25-0.74). No differences were found in the other secondary outcomes.

INTERPRETATION

Overall mortality did not differ significantly between early and late norepinephrine administration for septic shock. However, early norepinephrine administration seemed to reduce pulmonary edema incidence, and mortality improvement was observed in studies without fluid restriction interventions, favoring early norepinephrine use.

Value function assessment to different RL algorithms for heparin treatment policy of patients with sepsis in ICU

Heparin is a critical aspect of managing sepsis after abdominal surgery, which can improve microcirculation, protect organ function, and reduce mortality. However, there is no clinical evidence to support decision-making for heparin dosage. This paper proposes a model called SOFA-MDP, which utilizes SOFA scores as states of MDP, to investigate clinic policies. Different algorithms provide different value functions, making it challenging to determine which value function is more reliable. Due to ethical restrictions, we cannot test all policies on patients. To address this issue, we proposed two value function assessment methods: action similarity rate and relative gain. We experimented with heparin treatment policies for sepsis patients after abdominal surgery using MIMIC-IV. In the experiments, TD(0) shows the most reliable performance. Using the action similarity rate and relative gain to assess AI policy from TD(0), the agreement rates between AI policy and "good" physician's actual treatment are 64.6% and 73.2%, while the agreement rates between AI policy and "bad" physician's actual treatment are 44.1% and 35.8%, the gaps are 20.5% and 37.4%, respectively. External validation using action similarity rate and relative gain based on eICU resulted in agreement rates of 61.5% and 69.1% with the "good" physician's treatment, and 45.2% and 38.3% with the "bad" physician's treatment, with gaps of 16.3% and 30.8%, respectively. In conclusion, the model provides instructive support for clinical decisions, and the evaluation methods accurately distinguish reliable and unreasonable outcomes.

Early sepsis in Australia and New Zealand: A point-prevalence study of haemodynamic resuscitation practices

OBJECTIVE

Optimal resuscitation of sepsis-induced hypotension is uncertain, particularly the role of restrictive fluid strategies, leading to variability in usual practice. The objective of this study is to understand resuscitation practices in patients presenting to ED with early sepsis.

METHODS

Design, participants and setting: Prospective, observational, multicentre, single-day, point-prevalence study enrolling adult patients present in 51 Australian and New Zealand ICUs at 10.00 hours, 8 June 2021.

MAIN OUTCOME MEASURES

Site-level data on sepsis policies and patient-level demographic data, presence of sepsis and fluid and vasopressor administration in the first 24 h post-ED presentation.

RESULTS

A total of 722 patients were enrolled. ED was the ICU admission source for 222 of 722 patients (31.2%) and 78 of 222 patients (35%) met the criteria for sepsis within 24 h of ED presentation. Median age of the sepsis cohort was 61 (48-72) years, 58% were male and respiratory infection was the commonest cause (53.8%). The sepsis cohort had a higher severity of illness than the non-sepsis cohort (144/222 patients) and chronic immunocompromise was more common. Of 78 sepsis patients, 55 (71%) received ≥1 fluid boluses with 500 and 1000 mL boluses equally common (both 49%). In the first 24 h, 2335 (1409-3125) mL (25.3 [13.2-42.9] mL/kg) was administered. Vasopressors were administered in 53 of 78 patients (68%) and for 25 patients (47%) administration was peripheral.

CONCLUSIONS

ICU patients presenting to the ED with sepsis receive less fluids than current international recommendations and peripheral vasopressor administration is common. This finding supports the conduct of clinical trials evaluating optimal fluid dose and vasopressor timing for early sepsis-induced hypotension.

The Effect of Fluid Resuscitation Timing in Early Sepsis Resuscitation

PURPOSE

The dose and timing of early fluid resuscitation in sepsis remains a debated topic. The objective of this study is to evaluate the effect of fluid timing in early sepsis management on mortality and other clinical outcomes.

METHODS

Single-center, retrospective cohort study of emergency-department-treated adults (>18 years, n = 1032) presenting with severe sepsis or septic shock. Logistic regression evaluating the impact of 30 mL/kg crystalloids timing and mortality-versus-time plot controlling for mortality in emergency department sepsis score, lactate, antibiotic timing, obesity, sex, systemic inflammatory response syndrome criteria, hypotension, and heart and renal failures. This study is a subanalysis of a previously published investigation.

RESULTS

Mortality was 17.1% (n = 176) overall and 20.4% (n = 133 of 653) among those in septic shock. 30 mL/kg was given to 16.9%, 32.2%, 16.2%, 14.5%, and 20.3% of patients within ≤1, 1 ≤ 3, 3 ≤ 6, 6 ≤ 24, and not reached within 24 h, respectively. A 24-h plot of adjusted mortality versus time did not reach significance, but within the first 12 h, the linear function showed a per-hour mortality increase (odds ratio [OR] 1.29, 95% confidence interval [CI] 1.02-1.67) which peaks around 5h, although the quadratic function does not reach significance (P = .09). When compared to patients receiving 30 mL/kg within 1 h, increased mortality was observed when not reached within 24 h (OR 2.69, 95% CI 1.37-5.37) but no difference when receiving this volume between 1 and 3 (OR 1.11, 95% CI 0.62-2.01), 3 and 6 (OR 1.83, 95% CI 0.97-3.52), or 6 and 24 h (OR 1.51, 95% CI 0.75-3.06). Receiving 30 mL/kg between 1 and 3 versus <1 h increased the incidence of delayed hypotension (OR 1.83, 95% CI 1.23-2.72) but did not impact need for intubation, intensive care unit admission, or vasopressors.

CONCLUSIONS

We observed weak evidence that supports that earlier is better for survival when reaching fluid goals of 30 mL/kg, but benefits may wane at later time points. These findings should be viewed as hypothesis generating.

INITIATION TIMING OF VASOPRESSOR IN PATIENTS WITH SEPTIC SHOCK: A SYSTEMATIC REVIEW AND META-ANALYSIS

ABSTRACT

Background: Vasopressor plays a crucial role in septic shock. However, the time for vasopressor initiation remains controversial. We conducted a systematic review and meta-analysis to explore its initiation timing for septic shock patients. Methods: PubMed, Cochrane Library, Embase, and Web of Sciences were searched from inception to July 12, 2023, for relevant studies. Primary outcome was short-term mortality. Meta-analysis was performed using Stata 15.0. Results: Twenty-three studies were assessed, including 2 randomized controlled trials and 21 cohort studies. The early group resulted in lower short-term mortality than the late group (OR [95% CI] = 0.775 [0.673 to 0.893], P = 0.000, I2 = 67.8%). The significance existed in the norepinephrine and vasopressin in subgroup analysis. No significant difference was considered in the association between each hour's vasopressor delay and mortality (OR [95% CI] = 1.02 [0.99 to 1.051], P = 0.195, I2 = 57.5%). The early group had an earlier achievement of target MAP ( P < 0.001), shorter vasopressor use duration ( P < 0.001), lower serum lactate level at 24 h ( P = 0.003), lower incidence of kidney injury ( P = 0.001), renal replacement therapy use ( P = 0.022), and longer ventilation-free days to 28 days ( P < 0.001). Conclusions: Early initiation of vasopressor (1-6 h within septic shock onset) would be more beneficial to septic shock patients. The conclusion needs to be further validated by more well-designed randomized controlled trials.

Evolving Management Practices for Early Sepsis-induced Hypoperfusion: A Narrative Review

Sepsis causes significant morbidity and mortality worldwide. Resuscitation is a cornerstone of management. This review covers five areas of evolving practice in the management of early sepsis-induced hypoperfusion: fluid resuscitation volume, timing of vasopressor initiation, resuscitation targets, route of vasopressor administration, and use of invasive blood pressure monitoring. For each topic, we review the seminal evidence, discuss the evolution of practice over time, and highlight questions for additional research. Intravenous fluids are a core component of early sepsis resuscitation. However, with growing concerns about the harms of fluid, practice is evolving toward smaller-volume resuscitation, which is often paired with earlier vasopressor initiation. Large trials of fluid-restrictive, vasopressor-early strategies are providing more information about the safety and potential benefit of these approaches. Lowering blood pressure targets is a means to prevent fluid overload and reduce exposure to vasopressors; mean arterial pressure targets of 60-65 mm Hg appear to be safe, at least in older patients. With the trend toward earlier vasopressor initiation, the need for central administration of vasopressors has been questioned, and peripheral vasopressor use is increasing, although it is not universally accepted. Similarly, although guidelines suggest the use of invasive blood pressure monitoring with arterial catheters in patients receiving vasopressors, blood pressure cuffs are less invasive and often sufficient. Overall, the management of early sepsis-induced hypoperfusion is evolving toward fluid-sparing and less-invasive strategies. However, many questions remain, and additional data are needed to further optimize our approach to resuscitation.

A dosing strategy model of deep deterministic policy gradient algorithm for sepsis patients

BACKGROUND

A growing body of research suggests that the use of computerized decision support systems can better guide disease treatment and reduce the use of social and medical resources. Artificial intelligence (AI) technology is increasingly being used in medical decision-making systems to obtain optimal dosing combinations and improve the survival rate of sepsis patients. To meet the real-world requirements of medical applications and make the training model more robust, we replaced the core algorithm applied in an AI-based medical decision support system developed by research teams at the Massachusetts Institute of Technology (MIT) and IMPERIAL College London (ICL) with the deep deterministic policy gradient (DDPG) algorithm. The main objective of this study was to develop an AI-based medical decision-making system that makes decisions closer to those of professional human clinicians and effectively reduces the mortality rate of sepsis patients.

METHODS

We used the same public intensive care unit (ICU) dataset applied by the research teams at MIT and ICL, i.e., the Multiparameter Intelligent Monitoring in Intensive Care III (MIMIC-III) dataset, which contains information on the hospitalizations of 38,600 adult sepsis patients over the age of 15. We applied the DDPG algorithm as a strategy-based reinforcement learning approach to construct an AI-based medical decision-making system and analyzed the model results within a two-dimensional space to obtain the optimal dosing combination decision for sepsis patients.

RESULTS

The results show that when the clinician administered the exact same dose as that recommended by the AI model, the mortality of the patients reached the lowest rate at 11.59%. At the same time, according to the database, the baseline mortality rate of the patients was calculated as 15.7%. This indicates that the patient mortality rate when difference between the doses administered by clinicians and those determined by the AI model was zero was approximately 4.2% lower than the baseline patient mortality rate found in the dataset. The results also illustrate that when a clinician administered a different dose than that recommended by the AI model, the patient mortality rate increased, and the greater the difference in dose, the higher the patient mortality rate. Furthermore, compared with the medical decision-making system based on the Deep-Q Learning Network (DQN) algorithm developed by the research teams at MIT and ICL, the optimal dosing combination recommended by our model is closer to that given by professional clinicians. Specifically, the number of patient samples administered by clinicians with the exact same dose recommended by our AI model increased by 142.3% compared with the model based on the DQN algorithm, with a reduction in the patient mortality rate of 2.58%.

CONCLUSIONS

The treatment plan generated by our medical decision-making system based on the DDPG algorithm is closer to that of a professional human clinician with a lower mortality rate in hospitalized sepsis patients, which can better help human clinicians deal with complex conditional changes in sepsis patients in an ICU. Our proposed AI-based medical decision-making system has the potential to provide the best reference dosing combinations for additional drugs.

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.

[Fluid Management in Intensive Care Patients - New Strategies and optimal target?]

Adequate therapy with intravenous fluids is crucial in the initial treatment of critically ill patients. Both hypovolemia and hypervolemia are associated with organ dysfunction and adverse outcomes. A recent international randomized trial investigated a restrictive volume management in comparison with a standard volume regimen. 90-day-mortality was not significantly reduced in the group with restrictive fluid administration. Instead of using a fixed fluid strategy - either restrictive or liberal - fluid therapy should be individualised: Adequate fluid application optimizes cardiac preload and tissue perfusion and avoids the harms of abundant volume therapy. Early use of vasopressors may facilitate the achievement of mean arterial pressure targets and minimize the risk of volume overload. Appropriate volume management requires evaluation of fluid status, knowledge of hemodynamic parameters and accurate testing of fluid responsiveness. Regarding the absence of evidence-based criterias and treatment goals for volume management in shock patients, an individualised approach resorting to diverse monitoring tools should be considered. UItrasound-based assessment of IVC diameter and echocardiography are excellent non-invasive tools to evaluate volume status. Passive leg raising (PLR) test represents a valid method for the assessment of volume responsiveness.

Influence of time from admission to norepinephrine administration and volume of fluids received on outcomes of patients meeting sepsis-3 criteria: a retrospective study using the MIMIC-IV database

Objectives

Vasopressors are a cornerstone in the management of sepsis, marked by distributive shock often unresponsive to fluid resuscitation. Prior research and clinician surveys have suggested that earlier usage of vasopressors corresponds to improved outcomes.

Methods

A retrospective cohort was constructed using patient data contained within the Medical Information Mart for Intensive Care-IV database. Analytic cohort included a total of 2079 patients meeting sepsis-3 criteria with a ≥2-point rise in Sequential Organ Failure Assessment score and administered norepinephrine (NE) as first-line vasopressor within 24 hours of admission to the intensive care unit (ICU). Patients receiving other vasopressors or missing documented fluid resuscitation information were excluded. Primary end points included mortality, use of invasive mechanical ventilation and length of stay which were analyzed in a multivariate logistic regression model for the primary effect of time from ICU admission to NE administration using covariates.

Results

Time to NE use was defined as either early, using <6 hours from time of ICU admission or late using >6 hours to ≤24 hours. Patients who received early NE had significantly lower adjusted odds of mortality (0.75, 95% CI 0.57 to 0.97, p=0.026), higher adjusted odds of invasive mechanical ventilation (1.48, 95% CI 1.01 to 2.16, p=0.045), no significant difference in hospital length of stay (difference in days 0.6 (95% CI -3.24 to 2.04)) and lower ICU length of stay (difference in days -0.9 (95% CI -1.74 to -0.01)), as compared with the late NE group.

Conclusion

Among patients admitted to the ICU for sepsis, early use of NE was associated with significantly lower odds of mortality but higher odds of mechanical ventilation, and no significant difference in length of hospital stay but less time in the ICU. Furthermore, the volume of fluids received prior to NE use may have a significant impact on optimal NE timing.

Level of evidence

Level IV-therapeutic care/management.

Feasibility of intelligent drug control in the maintenance phase of general anesthesia based on convolutional neural network

Background

The growth and aging process of the human population has accelerated the increase in surgical procedures. Yet, the demand for increasing operations can be hardly met since the training of anesthesiologists is usually a long-term process. Closed-loop artificial intelligence (AI) model provides the possibility to solve intelligent decision-making for anesthesia auxiliary control and, as such, has allowed breakthroughs in closed-loop control of clinical practices in intensive care units (ICUs). However, applying an open-loop artificial intelligence algorithm to build up personalized medication for anesthesia still needs to be further explored. Currently, anesthesiologists have selected doses of intravenously pumped anesthetic drugs mainly based on the blood pressure and bispectral index (BIS), which can express the depth of anesthesia. Unfortunately, BIS cannot be monitored at some medical centers or operational procedures and only be regulated by blood pressure. As a result, here we aim to inaugurally explore the feasibility of a basic intelligent control system applied to drug delivery in the maintenance phase of general anesthesia, based on a convolutional neural network model with open-loop design, according to AI learning of existing anesthesia protocols.

Methods

A convolutional neural network, combined with both sliding window sampling method and residual learning module, was utilized to establish an "AI anesthesiologist" model for intraoperative dosing of personalized anesthetic drugs (propofol and remifentanil). The fitting degree and difference in pumping dose decision, between the AI anesthesiologist and the clinical anesthesiologist, for these personalized anesthetic drugs were examined during the maintenance phase of anesthesia.

Results

The medication level established by the "AI anesthesiologist" was comparable to that obtained by the clinical anesthesiologist during the maintenance phase of anesthesia.

Conclusion

The application of an open-loop decision-making plan by convolutional neural network showed that intelligent anesthesia control is consistent with the actual anesthesia control, thus providing possibility for further evolution and optimization of auxiliary intelligent control of depth of anesthesia.

Fluid Resuscitation in Patients Presenting with Sepsis: Current Insights

Intravenous (IV) fluid resuscitation is a key component of the initial resuscitation of septic shock, with international consensus guidelines suggesting the administration of at least 30mL/kg of isotonic crystalloid fluid. The rationale is to restore circulating fluid volume and optimise stroke volume. It is acknowledged that there is a paucity of high-level evidence to support this strategy, with most studies being observational or retrospective in design. In the past decade, evidence has emerged that a large positive fluid balance is associated with worse outcomes among patients with septic shock in intensive care who have already received initial resuscitation. Randomised trials undertaken in low-income countries have found increased mortality among patients with sepsis and hypoperfusion administered a larger fluid volume as part of initial resuscitation, however, translating these findings to other settings is not possible. This uncertainty has led to variation in practice with some advocating a more conservative fluid strategy coupled with the earlier introduction of vasopressors for haemodynamic support. This question is the subject of several ongoing clinical trials. This article summarises the current state of the evidence for IV fluid resuscitation in septic shock and provides guidance for practitioners in the face of our evolving understanding of this important area.

An interpretable RL framework for pre-deployment modeling in ICU hypotension management

Computational methods from reinforcement learning have shown promise in inferring treatment strategies for hypotension management and other clinical decision-making challenges. Unfortunately, the resulting models are often difficult for clinicians to interpret, making clinical inspection and validation of these computationally derived strategies challenging in advance of deployment. In this work, we develop a general framework for identifying succinct sets of clinical contexts in which clinicians make very different treatment choices, tracing the effects of those choices, and inferring a set of recommendations for those specific contexts. By focusing on these few key decision points, our framework produces succinct, interpretable treatment strategies that can each be easily visualized and verified by clinical experts. This interrogation process allows clinicians to leverage the model’s use of historical data in tandem with their own expertise to determine which recommendations are worth investigating further e.g. at the bedside. We demonstrate the value of this approach via application to hypotension management in the ICU, an area with critical implications for patient outcomes that lacks data-driven individualized treatment strategies; that said, our framework has broad implications on how to use computational methods to assist with decision-making challenges on a wide range of clinical domains.

The effect of continuous intravenous norepinephrine infusion on systemic hemodynamics in a telemetrically-monitored mouse model of sepsis

Sepsis, a life-threatening organ dysfunction, results from dysregulated host responses to infection and still has a high incidence and mortality. Although administration of vasopressors to treat septic shock is standard of care, the benefits are not well established. We evaluated the effect of continuous intravenous norepinephrine infusion in a septic cecal ligation and puncture (CLP) mouse model, evaluating systemic hemodynamics and body temperature post-hoc. CLP surgery significantly decreased mean arterial blood pressure (MAP), heart rate, and body temperature within six hours. Continuous norepinephrine infusion (NE+, n = 12) started at the time of CLP surgery significantly increased MAP at 24 and 30 hours and heart rate at 6, 18, 24, and 30 hours after CLP vs CLP alone (NE-, n = 12). However, addition of norepinephrine did not improve survival rate (NE+ n = 34, NE- n = 31). Early (6 hours or earlier, when the animal became visibly sick) MAP did not predict 7-day mortality. However, heart rates at 3 and at 6 hours after CLP/norepinephrine (NE+) were highly predictive of mortality, as also been found in one clinical study. We conclude that limited hemodynamic support can be provided in a mouse sepsis model. We propose that heart rate can be used to stratify severity of illness in rodent preclinical studies of sepsis therapeutics.

[Vasoactive drugs in the treatment of septic shock]

Septic shock is a high mortality complication frequently associated with sepsis. Early initiation of vasopressor treatment, even before completion of initial fluid resuscitation, is a determining factor in prognosis. In this sense, norepinephrine continues to be the drug of first choice, although there is increasing evidence of benefit combining it with other non-adrenergic drugs, such as vasopressin, instead of escalating norepinephrine doses. The pathophysiology of septic shock is multifactorial, and sometimes is associated with a situation of myocardial dysfunction that contributes to hemodynamic instability. It is essential to identify this situation since it worsens the prognosis and may benefit from combined treatment with inotropic drugs. There are novel vasoactive agents under study, more selective than the classic ones that in a next future could help to design more individualized and precise treatments. In the present work, the current knowledge about vasoactive drugs and their use in the management of septic shock is summarized according to the most recent scientific evidence.

Influence of Timing and Catecholamine Requirements on Vasopressin Responsiveness in Critically ill Patients with Septic Shock

Introduction: Despite its widespread use, there is a paucity of data to guide the optimal use of arginine vasopressin (AVP) in critically ill patients with septic shock. Methods: This multicenter retrospective cohort study conducted in critically ill adults sought to evaluate the role of catecholamine requirements and timing on responsiveness to AVP. Responsiveness was defined as both a decrease in ≥ 50% of catecholamine requirements and no decrease in mean arterial pressure (MAP) at 4 hours post-AVP initiation. Primary outcomes of interest included the proportion of patients who started AVP within 4 hours after starting catecholamine therapy, as well as baseline norepinephrine (NE) equivalents (< 15, 15-39, or ≥ 40 mcg/min). Multivariate analyses and logistic regression were performed to identify other factors associated with AVP responsiveness. Results: There were 300 patients included in this study, with 74 patients being responders and 226 being non-responders. There was no significant difference in the number of patients who received AVP within 4 hours from catecholamine initiation between responders and non-responders (35% vs. 42%, P = 0.29). There were more patients in the non-responder group requiring ≥ 40 mcg/min of NE equivalents at AVP initiation (30% vs. 16%, P = 0.023). Stress dose steroid use was less common in responders (35% vs. 52%, P = 0.011), which was consistent with logistic regression analysis (OR 0.56, 95% 0.32-0.98, P = 0.044). Clinical outcomes between responders and non-responders were similar, apart from ICU (5.4% vs. 19.5%) and hospital (5.4% vs. 20.4%) mortality being lower in responders (P = 0.0032 and P = 0.0002, respectively). Conclusion: Shorter times to AVP initiation was not associated with responsiveness at 4 hours post-catecholamine initiation, although non-responders tended to require higher doses of NE equivalents at time of AVP initiation. Concomitant corticosteroids were associated with a lower likelihood of AVP responsiveness.

[Fluid management in shock patients : New targets in the initial phase of shock]

BACKGROUND

Early i.v. fluid administration is a cornerstone in modern therapy of shock, especially in septic shock. However, there is much uncertainty concerning the amount and rate of fluid and which goals and measures could guide fluid management. Administering the optimal fluid volume is important because fluid overload can lead to severe negative consequences like organ failure and worsening of patient's outcome.

AIM

This review aims to describe the importance of fluid therapy and discuss possible strategies in fluid management as well as possible measurements and goals to guide such therapy.

RECENT FINDINGS

There is no single measurement to guide fluid management alone. It is important to assess fluid responsiveness, which together with multiple other parameters can be used to repeatedly assess optimal fluid management. However, it has also not been shown that assessing fluid responsiveness can improve outcome.

CONCLUSIONS

After the initial resuscitation, further fluid administration should be determined by individual patient factors and measures of fluid responsiveness. A more restrictive fluid management with early vasopressor administration seems to be increasingly used in modern fluid management. However many questions regarding optimal fluid management remain to be solved.

Evaluation of Evidence, Pharmacology, and Interplay of Fluid Resuscitation and Vasoactive Therapy in Sepsis and Septic Shock

ABSTRACT

We sought to review the pharmacology of vasoactive therapy and fluid administration in sepsis and septic shock, with specific insight into the physiologic interplay of these agents. A PubMed/MEDLINE search was conducted using the following terms (vasopressor OR vasoactive OR inotrope) AND (crystalloid OR colloid OR fluid) AND (sepsis) AND (shock OR septic shock) from 1965 to October 2020. A total of 1,022 citations were reviewed with only relevant clinical data extracted. While physiologic rationale provides a hypothetical foundation for interaction between fluid and vasopressor administration, few studies have sought to evaluate the clinical impact of this synergy. Current guidelines are not in alignment with the data available, which suggests a potential benefit from low-dose fluid administration and early vasopressor exposure. Future data must account for the impact of both of these pharmacotherapies when assessing clinical outcomes and should assess personalization of therapy based on the possible interaction.

WSES/GAIS/SIS-E/WSIS/AAST global clinical pathways for patients with intra-abdominal infections

Intra-abdominal infections (IAIs) are common surgical emergencies and have been reported as major contributors to non-trauma deaths in hospitals worldwide. The cornerstones of effective treatment of IAIs include early recognition, adequate source control, appropriate antimicrobial therapy, and prompt physiologic stabilization using a critical care environment, combined with an optimal surgical approach. Together, the World Society of Emergency Surgery (WSES), the Global Alliance for Infections in Surgery (GAIS), the Surgical Infection Society-Europe (SIS-E), the World Surgical Infection Society (WSIS), and the American Association for the Surgery of Trauma (AAST) have jointly completed an international multi-society document in order to facilitate clinical management of patients with IAIs worldwide building evidence-based clinical pathways for the most common IAIs. An extensive non-systematic review was conducted using the PubMed and MEDLINE databases, limited to the English language. The resulting information was shared by an international task force from 46 countries with different clinical backgrounds. The aim of the document is to promote global standards of care in IAIs providing guidance to clinicians by describing reasonable approaches to the management of IAIs.

Should Vasopressors Be Started Early in Septic Shock?

Sepsis can influence blood volume, its distribution, vascular tone, and cardiac function. Persistent hypotension or the need for vasopressors after volume resuscitation is part of the definition of septic shock. Since increased positive fluid balance has been associated with increased morbidity and mortality in sepsis, timing of vasopressors in the treatment of septic shock seems crucial. However, conclusive evidence on timing and sequence of interventions with the goal to restore tissue perfusion is lacking. The aim of this narrative review is to depict the pathophysiology of hypotension in sepsis, evaluate how common interventions to treat hypotension interfere with physiology, and to give a resume of the results from clinical studies focusing on targets and timing of vasopressor in sepsis. The majority of studies comparing early versus late administration of vasopressors in septic shock are rather small, single-center, and retrospective. The range of "early" is between 1 and 12 hours. The available studies suggest a mean arterial pressure of 60 to 65 mm Hg as a threshold for increased risk of morbidity and mortality, whereas higher blood pressure targets do not seem to add further benefits. The data, albeit mostly from observational studies, speak for combining vasopressors with fluids rather "early" in the treatment of septic shock (within a 0-3-hour window). Nevertheless, the optimal resuscitation strategy should take into account the source of infection, the pathophysiology, the time and clinical course preceding the diagnosis of sepsis, and also comorbidities and sepsis-induced organ dysfunction.

Early compared to later commencement of vasopressors in the management of Emergency Department patients with sepsis and hypotension, a multi-centre observational study

AIM

To describe and compare early with late vasopressor commencement in emergency department (ED) patients with sepsis and hypotension.

METHODS

This is a sub-study of the ARISE FLUIDS observational study conducted in 70 EDs in Australia and New Zealand. Adults with suspected sepsis and hypotension who received a vasopressor infusion in the first 24 h after ED presentation were included. 'Early' was defined as vasopressor commenced within 2 h from a) sepsis recognition, or b) triage.

RESULTS

177 patients (mean age 68 years) received vasopressors and had a lactate of 3.0 (IQR 2.0-4.9) mmol/L and APACHE II score of 17.8 (SD 6.3). 110 (62%) received a single agent vasopressor with noradrenaline being the most common (n = 74) and 67 (38%) received multiple vasopressors, most commonly metaraminol then noradrenaline (20.3%, n = 36). One-third (34.7%, n = 62) had vasopressors started via a peripheral line. Vasopressors were started within 2 h of sepsis recognition in 74 patients and within 2 h of triage in 24 patients. Both early groups had a higher lactate (3.5 vs. 2.9mmol/L and 5.0 vs. 2.9mmol/L, both p <0.05) and received lower fluid volumes prior to vasopressor commencement (2.0 vs. 2.85 L and 1.55 vs. 2.4 L, both p <0.001), compared to patients receiving vasopressors later. No differences in duration of vasopressor infusion, need for organ support or in-hospital mortality were found.

CONCLUSION

Early vasopressor commencement was associated with the administration of lower intravenous fluid volumes but not with duration of vasopressor use, organ support or mortality. Large prospective studies addressing this question are required.

Individualized resuscitation strategy for septic shock formalized by finite mixture modeling and dynamic treatment regimen

BACKGROUND

Septic shock comprises a heterogeneous population, and individualized resuscitation strategy is of vital importance. The study aimed to identify subclasses of septic shock with non-supervised learning algorithms, so as to tailor resuscitation strategy for each class.

METHODS

Patients with septic shock in 25 tertiary care teaching hospitals in China from January 2016 to December 2017 were enrolled in the study. Clinical and laboratory variables were collected on days 0, 1, 2, 3 and 7 after ICU admission. Subclasses of septic shock were identified by both finite mixture modeling and K-means clustering. Individualized fluid volume and norepinephrine dose were estimated using dynamic treatment regime (DTR) model to optimize the final mortality outcome. DTR models were validated in the eICU Collaborative Research Database (eICU-CRD) dataset.

RESULTS

A total of 1437 patients with a mortality rate of 29% were included for analysis. The finite mixture modeling and K-means clustering robustly identified five classes of septic shock. Class 1 (baseline class) accounted for the majority of patients over all days; class 2 (critical class) had the highest severity of illness; class 3 (renal dysfunction) was characterized by renal dysfunction; class 4 (respiratory failure class) was characterized by respiratory failure; and class 5 (mild class) was characterized by the lowest mortality rate (21%). The optimal fluid infusion followed the resuscitation/de-resuscitation phases with initial large volume infusion and late restricted volume infusion. While class 1 transitioned to de-resuscitation phase on day 3, class 3 transitioned on day 1. Classes 1 and 3 might benefit from early use of norepinephrine, and class 2 can benefit from delayed use of norepinephrine while waiting for adequate fluid infusion.

CONCLUSIONS

Septic shock comprises a heterogeneous population that can be robustly classified into five phenotypes. These classes can be easily identified with routine clinical variables and can help to tailor resuscitation strategy in the context of precise medicine.

Evaluation of Vasopressor Exposure and Mortality in Patients With Septic Shock

OBJECTIVES

The objectives of this study were to: 1) determine the association between vasopressor dosing intensity during the first 6 hours and first 24 hours after the onset of septic shock and 30-day in-hospital mortality; 2) determine whether the effect of vasopressor dosing intensity varies by fluid resuscitation volume; and 3) determine whether the effect of vasopressor dosing intensity varies by dosing titration pattern.

DESIGN

Multicenter prospective cohort study between September 2017 and February 2018. Vasopressor dosing intensity was defined as the total vasopressor dose infused across all vasopressors in norepinephrine equivalents.

SETTING

Thirty-three hospital sites in the United States (n = 32) and Jordan (n = 1).

PATIENTS

Consecutive adults requiring admission to the ICU with septic shock treated with greater than or equal to 1 vasopressor within 24 hours of shock onset.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Out of 1,639 patients screened, 616 were included. Norepinephrine (93%) was the most common vasopressor. Patients received a median of 3,400 mL (interquartile range, 1,851-5,338 mL) during the 24 hours after shock diagnosis. The median vasopressor dosing intensity during the first 24 hours of shock onset was 8.5 μg/min norepinephrine equivalents (3.4-18.1 μg/min norepinephrine equivalents). In the first 6 hours, increasing vasopressor dosing intensity was associated with increased odds ratio of 30-day in-hospital mortality, with the strength of association dependent on concomitant fluid administration. Over the entire 24 hour period, every 10 μg/min increase in vasopressor dosing intensity was associated with an increased risk of 30-day mortality (adjusted odds ratio, 1.33; 95% CI, 1.16-1.53), and this association did not vary with the amount of fluid administration. Compared to an early high/late low vasopressor dosing strategy, an early low/late high or sustained high vasopressor dosing strategy was associated with higher mortality.

CONCLUSIONS

Increasing vasopressor dosing intensity during the first 24 hours after septic shock was associated with increased mortality. This association varied with the amount of early fluid administration and the timing of vasopressor titration.

Safety-driven design of machine learning for sepsis treatment

Machine learning (ML) has the potential to bring significant clinical benefits. However, there are patient safety challenges in introducing ML in complex healthcare settings and in assuring the technology to the satisfaction of the different regulators. The work presented in this paper tackles the urgent problem of proactively assuring ML in its clinical context as a step towards enabling the safe introduction of ML into clinical practice. In particular, the paper considers the use of deep Reinforcement Learning, a type of ML, for sepsis treatment. The methodology starts with the modelling of a clinical workflow that integrates the ML model for sepsis treatment recommendations. Then safety analysis is carried out based on the clinical workflow, identifying hazards and safety requirements for the ML model. In this paper the design of the ML model is enhanced to satisfy the safety requirements for mitigating a major clinical hazard: sudden change of vasopressor dose. A rigorous evaluation is conducted to show how these requirements are met. A safety case is presented, providing a basis for regulators to make a judgement on the acceptability of introducing the ML model into sepsis treatment in a healthcare setting. The overall argument is broad in considering the wider patient safety considerations, but the detailed rationale and supporting evidence presented relate to this specific hazard. Whilst there are no agreed regulatory approaches to introducing ML into healthcare, the work presented in this paper has shown a possible direction for overcoming this barrier and exploit the benefits of ML without compromising safety.

Transatlantic transferability of a new reinforcement learning model for optimizing haemodynamic treatment for critically ill patients with sepsis

INTRODUCTION

In recent years, reinforcement learning (RL) has gained traction in the healthcare domain. In particular, RL methods have been explored for haemodynamic optimization of septic patients in the Intensive Care Unit. Most hospitals however, lack the data and expertise for model development, necessitating transfer of models developed using external datasets. This approach assumes model generalizability across different patient populations, the validity of which has not previously been tested. In addition, there is limited knowledge on safety and reliability. These challenges need to be addressed to further facilitate implementation of RL models in clinical practice.

METHOD

We developed and validated a new reinforcement learning model for hemodynamic optimization in sepsis on the MIMIC intensive care database from the USA using a dueling double deep Q network. We then transferred this model to the European AmsterdamUMCdb intensive care database. T-Distributed Stochastic Neighbor Embedding and Sequential Organ Failure Assessment scores were used to explore the differences between the patient populations. We apply off-policy policy evaluation methods to quantify model performance. In addition, we introduce and apply a novel deep policy inspection to analyse how the optimal policy relates to the different phases of sepsis and sepsis treatment to provide interpretable insight in order to assess model safety and reliability.

RESULTS

The off-policy evaluation revealed that the optimal policy outperformed the physician policy on both datasets despite marked differences between the two patient populations and physician's policies. Our novel deep policy inspection method showed insightful results and unveiled that the model could initiate therapy adequately and adjust therapy intensity to illness severity and disease progression which indicated safe and reliable model behaviour. Compared to current physician behavior, the developed policy prefers a more liberal use of vasopressors with a more restrained use of fluid therapy in line with previous work.

CONCLUSION

We created a reinforcement learning model for optimal bedside hemodynamic management and demonstrated model transferability between populations from the USA and Europe for the first time. We proposed new methods for deep policy inspection integrating expert domain knowledge. This is expected to facilitate progression to bedside clinical decision support for the treatment of critically ill patients.

Effect of norepinephrine combined with sodium phosphocreatine on cardiac function and prognosis of patients with septic shock

Septic shock (SS) leads to a high mortality rate for sepsis patients. Norepinephrine (NE) is a preferred vasoactive agent in SS treatment. This study aimed to assess the effects of NE at different administration time and NE combined with SP treatment on the cardiac function and prognosis of SS.

SS patients received NE treatment at different administration time and NE combined with SP treatment were enrolled in this study. The serum levels of cardiac troponin I (cTnI) and B-type natriuretic peptide (BNP), ejection fraction (EF), and pressure-adjusted heart rate (PAR) value were analyzed to evaluate cardiac function. The 28-day survival information was collected and assessed using the Kaplan-Meier method and log-rank test.

The cardiac function of SS patients was improved significantly by NE treatment, especially in the patients received NE at 2 h after fluid infusion, which evidenced by the increased BNP and cTnI levels and EF% and the decreased RAP. In the NE-2 h group, SS patients had a better 28-day survival rate compared with those patients in NE-1 h and -3 h groups. Furthermore, the significantly improved cardiac function and survival outcomes were found in patients received NE combined SP treatment.

Taken together, this study results show that NE administration at 2 h after fluid infusion may be the optimal time point for the treatment of SS and NE combined with SP treatment can improve early cardiac dysfunction and 28-day survival outcomes in patients with SS.

Dosing Fluids in Early Septic Shock

Early IV fluid administration remains one of the modern pillars of sepsis treatment; however, questions regarding amount, type, rate, mechanism of action, and even the benefits of fluid remain unanswered. Administering the optimal fluid volume is important, because overzealous fluid resuscitation can precipitate multiorgan failure, prolong mechanical ventilation, and worsen patient outcomes. After the initial resuscitation, further fluid administration should be determined by individual patient factors and measures of fluid responsiveness. This review describes various static and dynamic measures that are used to assess fluid responsiveness and summarizes the evidence addressing these metrics. Subsequently, we outline a practical approach to the evaluation of fluid responsiveness in early septic shock and explore further areas crucial to ongoing research examining this topic.

Incidence, Patient Characteristics, Mode of Drug Delivery, and Outcomes of Septic Shock Patients Treated With Vasopressors in the Arise Trial

INTRODUCTION

To describe the utilization of vasopressors (VP) in patients enrolled in the Australasian Resuscitation In Sepsis Evaluation (ARISE) trial, and to explore the association between time to VP and 90-day mortality.

METHODS

The primary exposure variable was VP use after arrival in the emergency department (ED). Vasoactive agents considered as VP included: norepinephrine, epinephrine, metaraminol, or vasopressin. Time-to-event analysis, multivariable logistic regression, and propensity-matched treatment effects modeling were used to assess the association between time to VP and 90-day mortality.

RESULTS

In total 1,102 of 1,588 patients (69%) in ARISE received VP at any point. The median [interquartile range (IQR)] time from ED presentation to commencing VP was 4.4 [2.7, 7.1] h, and 38% did so prior to central venous access. The median [IQR] volume of intravenous (i.v.) fluid administered prior to commencing VP was 3.1 [2.3, 4.3] L. Increasing age and volume of i.v. fluid therapy were associated with a lower likelihood of commencing VP early (within 4 h of ED presentation), while greater illness severity was associated with a higher likelihood, P < 0.001, respectively. In those who subsequently died within 90 days, the sub-hazard ratio (95% confidence interval) for commencing VP was 1.4 (1.20, 1.68), P < 0.001, adjusted for age, acute physiology and chronic health evaluation II score, study group, inclusion criteria, plasma lactate, i.v. fluid prior to VP, study institution, and site of infection.

DISCUSSION

50% of the ARISE cohort commenced VP within 4.4 h of ED presentation, and many did so prior to central venous access. Earlier initiation of VP was associated with greater crude and adjusted 90-day mortality.

Vasopressors in septic shock: which, when, and how much?

In addition to fluid resuscitation, the vasopressor therapy is a fundamental treatment of septic shock-induced hypotension as it aims at correcting the vascular tone depression and then at improving organ perfusion pressure. Experts’ recommendations currently position norepinephrine (NE) as the first-line vasopressor in septic shock. Vasopressin and its analogues are only second-line vasopressors as strong recent evidence suggests no benefit of their early administration in spite of promising preliminary data. Early administration of NE may allow achieving the initial mean arterial pressure (MAP) target faster and reducing the risk of fluid overload. The diastolic arterial pressure (DAP) as a marker of vascular tone, helps identifying the patients who need NE urgently. Available data suggest a MAP of 65 mmHg as the initial target but a more individualized approach is often required depending on several factors such as history of chronic hypertension or value of central venous pressure (CVP). In cases of refractory hypotension, increasing NE up to doses ≥1 µg/kg/min could be an option. However, current experts’ guidelines suggest to combine NE with other vasopressors such as vasopressin, with the intent to rising the MAP to target or to decrease the NE dosage.

Time to vasopressor initiation and organ failure progression in early septic shock

OBJECTIVE

Research evaluating the relationship between vasopressor initiation timing and clinical outcomes is limited and conflicting. We investigated the association between time to vasopressors, worsening organ failure, and mortality in patients with septic shock.

METHODS

This was a retrospective study of patients with septic shock (2013-2016) within 24 hours of emergency department (ED) presentation. The primary outcome was worsening organ failure, defined as an increase in Sequential Organ Failure Assessment (SOFA) score ≥2 at 48 hours compared to baseline, or death within 48 hours. The secondary outcome was 28-day mortality. Time to vasopressor initiation was categorized into 6, 4-hour intervals from time of ED triage. Multiple logistic regression was used to identify predictors of worsening organ failure.

RESULTS

We analyzed data from 428 patients with septic shock. There were 152 patients with the composite primary outcome (SOFA increase ≥2 or death at 48 hours). Of these, 77 patients died in the first 48 hours and 75 patients had a SOFA increase ≥2. Compared to the patients who received vasopressors in the first 4 hours, those with the longest time to vasopressors (20-24 hours) had increased odds of developing worsening organ failure (odds ratios [OR] = 4.34, 95% confidence intervals [CI] = 1.47-12.79, P = 0.008). For all others, the association between vasopressor timing and worsening organ failure was non-significant. There was no association between time to vasopressor initiation and 28-day mortality.

CONCLUSIONS

Increased time to vasopressor initiation is an independent predictor of worsening organ failure for patients with vasopressor initiation delays >20 hours.

Characteristics of resuscitation, and association between use of dynamic tests of fluid responsiveness and outcomes in septic patients: results of a multicenter prospective cohort study in Argentina

BACKGROUND

Resuscitation of septic patients regarding goals, monitoring aspects and therapy is highly variable. Our aim was to characterize cardiovascular and fluid management of sepsis in Argentina, a low and middle-income country (LMIC). Furthermore, we sought to test whether the utilization of dynamic tests of fluid responsiveness, as a guide for fluid therapy after initial resuscitation in patients with persistent or recurrent hypoperfusion, was associated with decreased mortality.

METHODS

Secondary analysis of a national, multicenter prospective cohort study (n = 787) fulfilling Sepsis-3 definitions. Epidemiological characteristics, hemodynamic management data, type of fluids and vasopressors administered, physiological variables denoting hypoperfusion, use of tests of fluid responsiveness, and outcomes, were registered. Independent predictors of mortality were identified with logistic regression analysis.

RESULTS

Initially, 584 of 787 patients (74%) had mean arterial pressure (MAP) < 65 mm Hg and/or signs of hypoperfusion and received 30 mL/kg of fluids, mostly normal saline (53%) and Ringer lactate (35%). Vasopressors and/or inotropes were administered in 514 (65%) patients, mainly norepinephrine (100%) and dobutamine (9%); in 22%, vasopressors were administered before ending the fluid load. After this, 413 patients (53%) presented persisting or recurrent hypotension and/or hypoperfusion, which prompted administration of additional fluid, based on: lactate levels (66%), urine output (62%), heart rate (54%), central venous O₂ saturation (39%), central venous-arterial PCO₂ difference (38%), MAP (31%), dynamic tests of fluid responsiveness (30%), capillary-refill time (28%), mottling (26%), central venous pressure (24%), cardiac index (13%) and/or pulmonary wedge pressure (3%). Independent predictors of mortality were SOFA and Charlson scores, lactate, requirement of mechanical ventilation, and utilization of dynamic tests of fluid responsiveness.

CONCLUSIONS

In this prospective observational study assessing the characteristics of resuscitation of septic patients in Argentina, a LMIC, the prevalent use of initial fluid bolus with normal saline and Ringer lactate and the use of norepinephrine as the most frequent vasopressor, reflect current worldwide practices. After initial resuscitation with 30 mL/kg of fluids and vasopressors, 413 patients developed persistent or recurrent hypoperfusion, which required further volume expansion. In this setting, the assessment of fluid responsiveness with dynamic tests to guide fluid resuscitation was independently associated with decreased mortality.

Establishing the Therapeutic Index of Fluid Resuscitation in the Septic Patient: A Narrative Review and Meta-Analysis

This comprehensive review comparatively evaluates the safety and benefits of parenteral fluids used in resuscitation with a focus on sepsis. It also provides a random-effects meta-analysis of studies comparing restrictive resuscitation and usual care in sepsis with the primary outcome of mortality. In the septic patient, fluid therapy remains a complex interplay between fluid compartments in the body, the integrity of the endothelial barrier, and the inflammatory tone of the patient. Recent data have emerged describing the pharmacokinetics of fluid resuscitation that can be affected by the factors just listed, as well as mean arterial pressure, rate of infusion, volume of fluid infusate, nature of the fluid, and drug interactions. Fluid overload in sepsis has been associated with vasodilation, kidney injury, and increased mortality. Restrictive resuscitation after the initial septic insult is an emerging practice. Our search strategy of Medline databases revealed six randomized studies with 706 patients that examined restrictive resuscitation in sepsis. Results of this meta-analysis demonstrated no differences in mortality with restrictive resuscitation compared with usual care (30.6% vs 37.8%; risk ratio 0.83, 95% confidence interval 0.66-1.05, respectively) but was limited by the small number of studies and larger quantities of pre-randomization fluids. Another approach to address fluid overload is active (diuresis) de-resuscitation strategies that may shorten the need for mechanical ventilation and intensive care unit length of stay. Data suggest that colloids may confer mortality benefit over saline in the most severely ill septic patients. Compared with isotonic saline, balanced resuscitation fluids are associated with a lower incidence of acute kidney injury and mortality. The benefits of balanced resuscitation fluids are most evident when higher volumes of fluids are used for sepsis. Clinicians should consider these pharmacotherapeutic factors when selecting a fluid, its quantity, and rate of infusion.

From a pressure-guided to a perfusion-centered resuscitation strategy in septic shock: Critical literature review and illustrative case

PURPOSE

To support a paradigm shift in the management of septic shock from pressure-guided to perfusion-centered, expected to improve outcome while reducing adverse effects from vasopressor therapy and aggressive fluid resuscitation.

MATERIAL AND METHODS

Critical review of the literature cited in support of vasopressor use to achieve a predefined mean arterial pressure (MAP) of 65 mmHg and review of pertinent clinical trials and studies enabling deeper understanding of the hemodynamic pathophysiology supportive of a perfusion-centered approach, accompanied by an illustrative case.

RESULTS

Review of the literature cited by the Surviving Sepsis Campaign revealed lack of controlled clinical trials supporting outcome benefits from vasopressors. Additional literature review revealed adverse effects associated with vasopressors and worsened outcome in some studies. Vasopressors increase MAP primarily by peripheral vasoconstriction and in occasions by a modest increase in cardiac output when using norepinephrine. Thus, achieving the recommended MAP of 65 mmHg using vasopressors should not be presumed indicative that organ perfusion has been restored. It may instead create a false sense of hemodynamic stability hampering shock resolution.

CONCLUSIONS

We propose focusing the hemodynamic management of septic shock on reversing organ hypoperfusion instead of attaining a predefined MAP target as the key strategy for improving outcome.

Delayed vasopressor initiation is associated with increased mortality in patients with septic shock

PURPOSE

Mortality rate for septic shock, despite advancements in knowledge and treatment, remains high. Treatment includes administration of broad-spectrum antibiotics and stabilization of the mean arterial pressure (MAP) with intravenous fluid resuscitation. Fluid-refractory shock warrants vasopressor initiation. There is a paucity of evidence regarding the timing of vasopressor initiation and its effect on patient outcomes.

MATERIALS AND METHODS

This retrospective, single-centered, cohort study included patients with septic shock from January 2017 to July 2017. Time from initial hypotension to vasopressor initiation was measured for each patient. The primary outcome was 30-day mortality.

RESULTS

Of 530 patients screened,119 patients were included. There were no differences in baseline patient characteristics. Thirty-day mortality was higher in patients who received vasopressors after 6 h (51.1% vs 25%, p < .01). Patients who received vasopressors within the first 6 h had more vasopressor-free hours at 72 h (34.5 h vs 13.1, p = .03) and shorter time to MAP of 65 mmHg (1.5 h vs 3.0, p < .01).

CONCLUSION

Vasopressor initiation after 6 h from shock recognition is associated with a significant increase in 30-day mortality. Vasopressor administration within 6 h was associated with shorter time to achievement of MAP goals and higher vasopressor-free hours within the first 72 h.

Norepinephrine and Vasopressin Compared With Norepinephrine and Epinephrine in Adults With Septic Shock

Background: The optimal adjuvant vasopressor to norepinephrine in septic shock remains controversial. Objective: To compare durations of shock-free survival between adjuvant vasopressin and epinephrine. Methods: A retrospective, single-center, matched cohort study of adults with septic shock refractory to norepinephrine was conducted. Patients receiving norepinephrine not at target mean arterial pressure (MAP; 65 mm Hg) were initiated on vasopressin or epinephrine to raise MAP to target. Vasopressin-exposed patients were matched to epinephrine-exposed patients using propensity scores. Mortality outcomes were examined using multivariable Poisson regression with robust variance estimation. Results: Of 166 patients, 96 (entire cohort) were included in the propensity score-matched cohort. Shock-free survival durations in the first 7 days were similar between epinephrine- and vasopressin-exposed patients in the matched cohort (median = 13.2 hours, interquartile range [IQR] = 0-121.0, vs median = 41.3 hours, IQR = 0-125.9; P = 0.51). Seven- and 28-day mortality rates were similar in the matched cohort (7-day: 47.9% vs 39.6%, P = 0.35; 28-day: 56.3% vs 58.3%, P = 0.84). Mortality rates were similar between epinephrine- and vasopressin-exposed patients in propensity score-matched regression models with and without adjustments at 7 (relative risk [RR] = 1.28, 95% CI = 0.92-1.79; RR = 1.21, 95% CI = 0.81-1.81) and 28 days (RR = 1.04, 95% CI = 0.81-1.34; RR = 0.96, 95% CI = 0.69-1.34). Conclusion and Relevance: Shock-free survival durations were similar in matched epinephrine- and vasopressin-exposed groups. Adjuvant epinephrine or vasopressin alongside norepinephrine to raise MAP to target requires further investigation.

Current use of vasopressors in septic shock

Background

Vasopressors are commonly applied to restore and maintain blood pressure in patients with sepsis. We aimed to evaluate the current practice and therapeutic goals regarding vasopressor use in septic shock as a basis for future studies and to provide some recommendations on their use.

Methods

From November 2016 to April 2017, an anonymous web-based survey on the use of vasoactive drugs was accessible to members of the European Society of Intensive Care Medicine (ESICM). A total of 17 questions focused on the profile of respondents, triggering factors, first choice agent, dosing, timing, targets, additional treatments, and effects of vasopressors. We investigated whether the answers complied with current guidelines. In addition, a group of 34 international ESICM experts was asked to formulate recommendations for the use of vasopressors based on 6 questions with sub-questions (total 14).

Results

A total of 839 physicians from 82 countries (65% main specialty/activity intensive care) responded. The main trigger for vasopressor use was an insufficient mean arterial pressure (MAP) response to initial fluid resuscitation (83%). The first-line vasopressor was norepinephrine (97%), targeting predominantly a MAP > 60–65 mmHg (70%), with higher targets in patients with chronic arterial hypertension (79%). The experts agreed on 10 recommendations, 9 of which were based on unanimous or strong (≥ 80%) agreement. They recommended not to delay vasopressor treatment until fluid resuscitation is completed but rather to start with norepinephrine early to achieve a target MAP of ≥ 65 mmHg.

Conclusion

Reported vasopressor use in septic shock is compliant with contemporary guidelines. Future studies should focus on individualized treatment targets including earlier use of vasopressors.

Pulse Pressure and Mortality Risk in Critically Ill Patients

BACKGROUND

Pulse pressure is a hemodynamic variable easily measured in the intensive care unit.

OBJECTIVE

To investigate whether pulse pressure is an independent risk factor for mortality in intensive care unit patients.

METHODS

A retrospective cohort study was carried out in Brazil. Data were collected from medical records of patients admitted to intensive care units from September to December 2012. Pulse pressure was calculated from systolic and diastolic blood pressures recorded during the first 24 hours of stay.

RESULTS

Records of 529 patients (mean [standard deviation] age 55.0 [17.3] years; 54.4% male, 45.6% female) were analyzed. Risk factors for mortality were age, use of vasoactive drugs, nursing workload, and length of stay in the intensive care unit. Analysis indicated that higher minimum pulse pressures were associated with lower mortality risk.

CONCLUSION

Pulse pressure was not found to be an independent risk factor for mortality in patients who are critically ill.

Mean arterial pressure and mortality in patients with distributive shock: a retrospective analysis of the MIMIC-III database

BACKGROUND

Maintenance of mean arterial pressure (MAP) at levels sufficient to avoid tissue hypoperfusion is a key tenet in the management of distributive shock. We hypothesized that patients with distributive shock sometimes have a MAP below that typically recommended and that such hypotension is associated with increased mortality.

METHODS

In this retrospective analysis of the Medical Information Mart for Intensive Care (MIMIC-III) database from Beth Israel Deaconess Medical Center, Boston, USA, we included all intensive care unit (ICU) admissions between 2001 and 2012 with distributive shock, defined as continuous vasopressor support for ≥ 6 h and no evidence of low cardiac output shock. Hypotension was evaluated using five MAP thresholds: 80, 75, 65, 60 and 55 mmHg. We evaluated the longest continuous episode below each threshold during vasopressor therapy. The primary outcome was ICU mortality.

RESULTS

Of 5347 patients with distributive shock, 95.7%, 91.0%, 62.0%, 36.0% and 17.2%, respectively, had MAP < 80, < 75, < 65, < 60 and < 55 mmHg for more than two consecutive hours. On average, ICU mortality increased by 1.3, 1.8, 5.1, 7.9 and 14.4 percentage points for each additional 2 h with MAP < 80, < 75, < 65, < 60 and < 55 mmHg, respectively. Multivariable logistic modeling showed that, compared to patients in whom MAP was never < 65 mmHg, ICU mortality increased as duration of hypotension < 65 mmHg increased [for > 0 to < 2 h, odds ratio (OR) 1.76, p = 0.005; ≥ 6 to < 8 h, OR 2.90, p < 0.0001; ≥ 20 h, OR 7.10, p < 0.0001]. When hypotension was defined as MAP < 60 or < 55 mmHg, the associations between duration and mortality were generally stronger than when hypotension was defined as MAP < 65 mmHg. There was no association between hypotension and mortality when hypotension was defined as MAP < 80 mmHg.

CONCLUSIONS

Within the limitations due to the nature of the study, most patients with distributive shock experienced at least one episode with MAP < 65 mmHg lasting > 2 h. Episodes of prolonged hypotension were associated with higher mortality.

The Artificial Intelligence Clinician learns optimal treatment strategies for sepsis in intensive care

Sepsis is the third leading cause of death worldwide and the main cause of mortality in hospitals^1-3, but the best treatment strategy remains uncertain. In particular, evidence suggests that current practices in the administration of intravenous fluids and vasopressors are suboptimal and likely induce harm in a proportion of patients^1,4-6. To tackle this sequential decision-making problem, we developed a reinforcement learning agent, the Artificial Intelligence (AI) Clinician, which extracted implicit knowledge from an amount of patient data that exceeds by many-fold the life-time experience of human clinicians and learned optimal treatment by analyzing a myriad of (mostly suboptimal) treatment decisions. We demonstrate that the value of the AI Clinician's selected treatment is on average reliably higher than human clinicians. In a large validation cohort independent of the training data, mortality was lowest in patients for whom clinicians' actual doses matched the AI decisions. Our model provides individualized and clinically interpretable treatment decisions for sepsis that could improve patient outcomes.

Review article: Sepsis in the emergency department - Part 3: Treatment

Although comprehensive guidelines for treatment of sepsis exist, current research continues to refine and revise several aspects of management. Imperatives for rapid administration of broad-spectrum antibiotics for all patients with sepsis may not be supported by contemporary data. Many patients may be better served by a more judicious approach allowing consideration of investigation results and evidence-based guidelines. Conventional fluid therapy has been challenged with early evidence supporting balanced, restricted fluid and early vasopressor use. Albumin, vasopressin and hydrocortisone have each been shown to support blood pressure and reduce catecholamine requirements but without effect on mortality, and as such should be considered for ED patients with septic shock on a case-by-case basis. Measurement of quality care in sepsis should incorporate quality of blood cultures and guideline-appropriateness of antibiotics, as well as timeliness of therapy. Local audit is an essential and effective means to improve practice. Multicentre consolidation of data through agreed minimum sepsis data sets would provide baseline quality data, required for the design and evaluation of interventions.

Neuroendocrine Derangements in Early Septic Shock: Pharmacotherapy for Relative Adrenal and Vasopressin Insufficiency

Septic shock is a leading cause of mortality in intensive care units throughout the world. While this disease state represents a highly complex pathophysiology involving numerous organ systems, the early approach to care includes adequate hemodynamic support traditionally achieved via infusions of vasoactive medications after adequate fluid resuscitation. Relative adrenal and vasopressin deficiencies are a common feature of septic shock that contribute to impaired hemodynamics. Hydrocortisone and vasopressin are endocrine system hormone analogues that target the acute neuroendocrine imbalance associated with septic shock. This clinically focused annotated review describes the pathophysiological mechanisms behind their use and explores the potential clinical roles of early administration and synergy when combined.

Postoperative hemodynamic instability and monitoring

PURPOSE OF REVIEW

The purpose of the review is to identify the recently validated minimally invasive or noninvasive monitoring devices used to both monitor and guide resuscitation in the critically ill patients.

RECENT FINDINGS

Recent advances in noninvasive measures of blood pressure, blood flow, and vascular tone have been validated and complement existing minimally invasive and invasive monitoring techniques. These monitoring approaches should be used within the context of a focused physical examination and static vital sign analysis. When available, measurement of urinary output is often included. All studies show that minimally invasive and noninvasive measure of arterial pressure and cardiac output are possible and often remain as accurate as invasive measures. The noninvasive techniques degrade in severe circulatory failure and the use of vasopressor therapy. Importantly, these output parameters form the treatment goals for many goal-directed therapies protocols.

SUMMARY

When coupled with a focused physical examination and functional hemodynamic monitoring analyses, these measures become even more specific at defining volume responsiveness and vasomotor tone and can be used to drive resuscitation strategies.