Re-thinking resuscitation: leaving blood pressure cosmetics behind and moving forward to permissive hypotension and a tissue perfusion-based approach

Damage Control Resuscitation in polytrauma patient

Haemorrhagic shock is one of the main causes of mortality in severe polytrauma patients. To increase the survival rates, a combined strategy of treatment known as Damage Control has been developed. The aims of this article are to analyse the actual concept of Damage Control Resuscitation and its three treatment levels, describe the best transfusion strategy, and approach the acute coagulopathy of the traumatic patient as an entity. The potential changes of this therapeutic strategy over the coming years are also described.

Assessment of Regional Perfusion and Organ Function: Less and Non-invasive Techniques

Sufficient organ perfusion essentially depends on preserved macro- and micro-circulation. The last two decades brought substantial progress in the development of less and non-invasive monitoring of macro-hemodynamics. However, several recent studies suggest a frequent incoherence of macro- and micro-circulation. Therefore, this review reports on interactions of macro- and micro-circulation as well as on specific regional and micro-circulation. Regarding global micro-circulation the last two decades brought advances in a more systematic approach of clinical examination including capillary refill time, a graded assessment of mottling of the skin and accurate measurement of body surface temperatures. As a kind of link between macro- and microcirculation, a number of biochemical markers can easily be obtained. Among those are central-venous oxygen saturation (S_cvO₂), plasma lactate and the difference between central-venous and arterial CO₂ (cv-a-pCO₂-gap). These inexpensive markers have become part of clinical routine and guideline recommendations. While their potential to replace parameters of macro-circulation such as cardiac output (CO) is limited, they facilitate the interpretation of the adequacy of CO and other macro-circulatory markers. Furthermore, they give additional hints on micro-circulatory impairment. In addition, a number of more sophisticated technical approaches to quantify and visualize micro-circulation including video-microscopy, laser flowmetry, near-infrared spectroscopy (NIRS), and partial oxygen pressure measurement have been introduced within the last 20 years. These technologies have been extensively used for scientific purposes. Moreover, they have been successfully used for educational purposes and to visualize micro-circulatory disturbances during sepsis and other causes of shock. Despite several studies demonstrating the association of these techniques and parameters with outcome, their practical application still is limited. However, future improvements in automated and “online” diagnosis will help to make these technologies more applicable in clinical routine. This approach is promising with regard to several studies which demonstrated the potential to guide therapy in different types of shock. Finally several organs have specific patterns of circulation related to their special anatomy (liver) or their auto-regulatory capacities (brain, kidney). Therefore, this review also discusses specific issues of monitoring liver, brain, and kidney circulation and function.

Hemodynamic response to β-blockers in severe sepsis and septic shock: A review of current literature

The administration of β-blockers in patients with sepsis is a trending topic in intensive care medicine since the landmark study by Morelli and colleagues, showing a striking decrease in 28-day mortality compared to standard care. While the available evidence suggests that the use of β-blockers in septic shock is safe, the effects on hemodynamics are controversial. In this paper, we review the effect of β-blockade in septic shock on hemodynamics from animal models to critically ill patients.

[Prognostic value of difference between peripheral venous and arterial partial pressure of carbon dioxide in patients with septic shock: a pilot study]

OBJECTIVE

To evaluate the prognostic value of the difference between peripheral venous and arterial partial pressure of carbon dioxide in patients with septic shock following early resuscitation.

METHODS

This prospective study was conducted among the patients with septic shock treated in our department during the period from May, 2017 to May, 2018. Peripheral venous, peripheral arterial and central venous blood samples were collected simultaneously and analyzed immediately at bedside after 6-h bundle treatment. Arterial blood lactate concentration (Lac) and the arterial (PaCO2), peripheral venous (PpvCO2) and central venous partial pressure of carbon dioxide (PcvCO2) were recorded. The differences between PpvCO2 and PaCO2 (Ppv-aCO2) and between PcvCO2 and PaCO2 (Pcv-aCO2) were calculated. Pearson correlation analysis was used to test the agreement between Pcv-aCO2 and Ppv-aCO2. Multivariable logistic regression analysis was performed to analyze the possible risk factors for 28-day mortality, and the receiver-operating characteristic curve (ROC) was plotted to assess the prognostic values of these factors for 28-day mortality.

RESULTS

A total of 62 patients were enrolled in this study, among who 35 survived and 27 died during the 28-day period. Compared with the survivor group, the patients died within 28 days showed significantly higher Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score (24.2±6.0 vs 20.5±4.9, P=0.011), sequential organ failure assessment (SOFA) score (14.9±4.7 vs 12.2±4.5, P=0.027), PcvaCO2 (5.5±1.6 vs 7.1±1.7, P < 0.001), PpvaCO2 (7.1±1.8 vs 10.0±2.7, P < 0.001), and arterial lactate level (3.3±1.2 vs 4.2±1.3, P=0.003) after 6-h bundle treatment. Pearson correlation analysis showed that Ppv-aCO2 was significantly correlated with Pcv-aCO2 (r=0.897, R2= 0.805, P < 0.001). Multiple logistic regression analysis identified Ppv-aCO2 (β=0.625, P=0.001, OR=1.869, 95% CI: 1.311-2.664) and lactate level (β=0.584, P=0.041, OR=1.794, 95%CI: 1.024-3.415) as the independent risk factors for 28-day mortality. The maximum area under the ROC (AUC) of Ppv-aCO2 was 0.814 (95%CI: 0.696- 0.931, P < 0.001), and at the best cut- off value of 9.05 mmHg, Ppv-aCO2 had a sensitivity of 70.4% and a specificity of 88.6% for predicting 28-day mortality. The AUC of lactate level was 0.732 (95%CI: 0.607-0.858, P=0.002), and its sensitivity for predicting 28-day mortality was 70.4% and the specificity was 74.3% at the best cut-off value of 3.45 mmol/L; The AUC of Pcv-aCO2 was 0.766 (95%CI: 0.642-0.891, P < 0.001), and its sensitivity was 66.7% and the specificity was 80.0% at the best cut-off value of 7.05 mmHg.

CONCLUSIONS

A high Ppv-aCO2 after early resuscitation of septic shock is associated with poor outcomes. Ppv-aCO2 is well correlated with Pcv-aCO2 and can be used as an independent indicator for predicting 28-day mortality in patients with septic shock.

Pre-operative haemodynamic monitoring and resuscitation in hip fracture patients: Protocol for a prospective observational study

BACKGROUND

In a frail patient group often suffering from dehydration, hip fracture is potentially fatal partly because of the blood loss and thus deteriorated circulation. An important goal for haemodynamic monitoring and resuscitation is early detection of insufficient tissue perfusion. "The peripheral perfusion index" reflects changes in peripheral perfusion and blood volume. We hypothesize that hip fracture patients are hypovolaemic with poor peripheral perfusion and accordingly respond to controlled fluid resuscitation. The peripheral perfusion index might reflect restricted tissue perfusion in spite of stable central haemodynamic variables.

METHODS

This prospective observational study assess to what extend hip fracture patients suffer from hypovolaemia and respond to a stroke volume-guided fluid challenge. The secondary objectives are to evaluate correlation between the non-invasive peripheral perfusion index and minimally invasive measures of stroke volume, changes in blood volume and near-infrared spectroscopy determined tissue- and cerebral oxygenation and to compare results to prevalence of post-operative complications including mortality. We will include 50 patients (>65 years) presenting a hip fracture and treated in a multimodal fast-track regimen when written informed consent is available.

DISCUSSION

This is likely the first study to address pre-operative haemodynamic monitoring and resuscitation in hip fracture patients where adequate resuscitation is easily missed. We aim to evaluate feasibility of pre-operative stroke volume-guided haemodynamic optimization in the context of minimally- and non-invasive monitoring of peripheral perfusion and measure of blood volume.

Oxygen-Flow-Pressure Targets for Resuscitation in Critical Hemodynamic Therapy

Far from traditional "vital signs," the field of hemodynamic monitoring (HM) is rapidly developing. However, it is also easy to misunderstand hemodynamic therapy as merely HM and some concrete bundles or guidelines for circulation support. Here, we describe the concept of "critical hemodynamic therapy" and clarify the concepts of the "therapeutic target" and "therapeutic endpoint" in clinical practice. Three main targets (oxygen delivery, blood flow, perfusion pressure) for resuscitation are reviewed in critically ill patients according to the sepsis guidelines and hemodynamic consensus. ScvO2 at least 70% has not been recommended as a directed target for initial resuscitation, and the directed target of mean arterial pressure (MAP) still is 65 mmHg. Moreover, the individual MAP target is underlined, and using flow-dependent monitoring to guide fluid infusion is recommended. The flow-directed target for fluid infusion might be a priority, but it remains controversial in resuscitation. The interpretation of these targets is necessary for adequate resuscitation and the correction of tissue hypoxia. The incoherence phenomenon of resuscitation (macrocirculation and microcirculation, tissue perfusion, and cellular oxygen utilization) is gaining increased attention, and early identification of these incoherences might be helpful to reduce the risk of over-resuscitation.

Septic shock resuscitation in the first hour

PURPOSE OF REVIEW

We reviewed the recent advances in the initial approach to resuscitation of sepsis and septic shock patients.

RECENT FINDINGS

Sepsis and septic shock are life-threatening emergencies. Two key interventions in the first hour include timely antibiotic therapy and resuscitation. Before any laboratory results, the need for resuscitation is considered if a patient with suspected infection has low blood pressure (BP) or impaired peripheral circulation found at clinical examination. Until now, this early resuscitation in sepsis and septic shock was supported by improvements in outcome seen with goal-directed therapy. However, three recent, goal-directed therapy trials failed to replicate the originally reported mortality reductions, prompting a debate on how this early resuscitation should be performed. As resuscitation is often focussed on macrociculatory goals such as optimizing central venous pressure, the discordance between microcirculatory and macrocirculatory optimization during resuscitation is a potential argument for the lack of outcome benefit in the newer trials. Vasoactive drug dose and large volume resuscitation-associated-positive fluid balance, are independently associated with worse clinical outcomes in critically ill sepsis and septic shock patients. As lower BP targets and restricted volume resuscitation are feasible and well tolerated, should we consider a lower BP target to reduce the adverse effects of catecholamine' and excess resuscitation fluids. Evidence guiding fluids, vasopressor, and inotrope selection remains limited.

SUMMARY

Though the early resuscitation of sepsis and septic shock is key to improving outcomes, ideal resuscitation targets are elusive. Distinction should be drawn between microcirculatory and macrocirculatory changes, and corresponding targets. Common components of resuscitation bundles such as large volume resuscitation and high-dose vasopressors may not be universally beneficial. Microcirculatory targets, individualized resuscitation goals, and reassessment of completed trials using the updated septic shock criteria should be focus areas for future research.

Lactate and microcirculation as suitable targets for hemodynamic optimization in resuscitation of circulatory shock

PURPOSE OF REVIEW

A discussion of recent research exploring the feasibility of perfusion-guided resuscitation of acute circulatory failure with a focus on lactate and microcirculation.

RECENT FINDINGS

Upon diagnosis of shock, hyperlactemia is associated with poor outcome and, under appropriate clinical circumstances, may reflect inadequate tissue perfusion. Persistent hyperlactemia despite resuscitation is even more strongly correlated with morbidity and mortality. Importantly, there is minimal coherence between lactate trends and static hemodynamic measures such as blood pressure, especially after the initial, hypovolemic phase of shock. During this early period, lactate guided-resuscitation is effective and possibly superior to hemodynamic-guided resuscitation. Similar to hyperlactemia, impaired microcirculation is ubiquitous in shock and is evident even in the setting of hemodynamic compensation (i.e., occult shock). Moreover, persistent microcirculatory derangement is associated with poor outcome and may reflect ongoing shock and/or long-lasting damage. Although the wait continues for a microcirculation-guided resuscitation trial, there is progress toward this goal.

SUMMARY

Although questions remain, a multimodal perfusion-based approach to resuscitation is emerging with lactate and microcirculation as core measures. In this model, hyperlactemia and microcirculatory derangement support the diagnosis of shock, may help guide resuscitation during the initial period, and may reflect resuscitation efficacy and iatrogenic harm (e.g., fluid overload).

Early goal-directed therapy using a physiological holistic view: the ANDROMEDA-SHOCK-a randomized controlled trial

Background

Septic shock is a highly lethal condition. Early recognition of tissue hypoperfusion and its reversion are key factors for limiting progression to multiple organ dysfunction and death. Lactate-targeted resuscitation is the gold-standard under current guidelines, although it has several pitfalls including that non-hypoxic sources of lactate might predominate in an unknown proportion of patients. Peripheral perfusion-targeted resuscitation might provide a real-time response to increases in flow that could lead to a more timely decision to stop resuscitation, thus avoiding fluid overload and the risks of over-resuscitation. This article reports the rationale, study design and analysis plan of the ANDROMEDA-SHOCK Study.

Methods

ANDROMEDA-SHOCK is a randomized controlled trial which aims to determine if a peripheral perfusion-targeted resuscitation is associated with lower 28-day mortality compared to a lactate-targeted resuscitation in patients with septic shock with less than 4 h of diagnosis. Both groups will be treated with the same sequential approach during the 8-hour study period pursuing normalization of capillary refill time versus normalization or a decrease of more than 20% of lactate every 2 h. The common protocol starts with fluid responsiveness assessment and fluid loading in responders, followed by a vasopressor and an inodilator test if necessary. The primary outcome is 28-day mortality, and the secondary outcomes are: free days of mechanical ventilation, renal replacement therapy and vasopressor support during the first 28 days after randomization; multiple organ dysfunction during the first 72 h after randomization; intensive care unit and hospital lengths of stay; and all-cause mortality at 90-day. A sample size of 422 patients was calculated to detect a 15% absolute reduction in mortality in the peripheral perfusion group with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle.

Conclusions

If peripheral perfusion-targeted resuscitation improves 28-day mortality, this could lead to simplified algorithms, assessing almost in real-time the reperfusion process, and pursuing more physiologically sound objectives. At the end, it might prevent the risk of over-resuscitation and lead to a better utilization of intensive care unit resources.

Trial registration ClinicalTrials.gov Identifier: NCT03078712 (registered retrospectively March 13th, 2017)

Comparative Evaluation of Crystalloid Resuscitation Rate in a Human Model of Compensated Haemorrhagic Shock

Introduction:

The most effective rate of fluid resuscitation in haemorrhagic shock is unknown.

Methods:

We performed a randomized crossover pilot study in a healthy volunteer model of compensated haemorrhagic shock. Following venesection of 15 mL/kg of blood, participants were randomized to 20 mL/kg of crystalloid over 10 min (FAST treatment) or 30 min (SLOW treatment). The primary end point was oxygen delivery (DO₂). Secondary end points included pressure and flow-based haemodynamic variables, blood volume expansion, and clinical biochemistry.

Results:

Nine normotensive healthy adult volunteers participated. No significant differences were observed in DO₂ and biochemical variables between the SLOW and FAST groups. Blood volume was reduced by 16% following venesection, with a corresponding 5% reduction in cardiac index (CI) (P < 0.001). Immediately following resuscitation the increase in blood volume corresponded to 54% of the infused volume under FAST treatment and 69% of the infused volume under SLOW treatment (P = 0.03). This blood volume expansion attenuated with time to 24% and 25% of the infused volume 30 min postinfusion. During fluid resuscitation, blood pressure was higher under FAST treatment. However, CI paradoxically decreased in most participants during the resuscitation phase; a finding not observed under SLOW treatment.

Conclusion:

FAST or SLOW fluid resuscitation had no significant impact on DO₂ between treatment groups. In both groups, changes in CI and blood pressure did not reflect the magnitude of intravascular blood volume deficit. Crystalloid resuscitation expanded intravascular blood volume by approximately 25%.

Enhanced Recovery after Vascular Surgery

The beginnings of the enhanced recovery after surgery (ERAS) program were first developed for patients in colorectal surgery, and after it was established as the standard of care in this surgical field, it began to be applied in many others surgical areas. This is multimodal, evidence-based approach program and includes simultaneous optimization of preoperative status of patients, adequate selection of surgical procedure and postoperative management. The aim of this program is to reduce complications, the length of hospital stay and to improve the patients outcome. Over the past decades, special attention was directed to the postoperative management in vascular surgery, especially after major vascular surgery because of the great risk of multiorgan failure, such as: respiratory failure, myocardial infarction, hemodynamic instability, coagulopathy, renal failure, neurological disorders, and intra-abdominal complications. Although a lot of effort was put into it, there is no unique acceptable program for ERAS in this surgical field, and there is still a need to point out the factors responsible for postoperative outcomes of these patients. So far, it is known that special attention should be paid to already existing diseases, type and the duration of the surgical intervention, hemodynamic and fluid management, nutrition, pain management, and early mobilization of patients.

Capillary refill time during fluid resuscitation in patients with sepsis-related hyperlactatemia at the emergency department is related to mortality

INTRODUCTION

Acute circulatory dysfunction in patients with sepsis can evolve rapidly into a progressive stage associated with high mortality. Early recognition and adequate resuscitation could improve outcome. However, since the spectrum of clinical presentation is quite variable, signs of hypoperfusion are frequently unrecognized in patients just admitted to the emergency department (ED). Hyperlactatemia is considered a key parameter to disclose tissue hypoxia but it is not universally available and getting timely results can be challenging in low resource settings. In addition, non-hypoxic sources can be involved in hyperlactatemia, and a misinterpretation could lead to over-resuscitation in an unknown number of cases. Capillary refill time (CRT) is a marker of peripheral perfusion that worsens during circulatory failure. An abnormal CRT in septic shock patients after ICU-based resuscitation has been associated with poor outcome. The aim of this study was to determine the prevalence of abnormal CRT in patients with sepsis-related hyperlactatemia in the early phase after ED admission, and its relationship with outcome.

METHODS

We performed a prospective observational study. Septic patients with hyperlactemia at ED admission subjected to an initial fluid resuscitation (FR) were included. CRT and other parameters were assessed before and after FR. CRT-normal or CRT-abnormal subgroups were defined according to the status of CRT following initial FR, and major outcomes were registered.

RESULTS

Ninety-five hyperlactatemic septic patients were included. Thirty-one percent had abnormal CRT at ED arrival. After FR, 87 patients exhibited normal CRT, and 8 an abnormal one. Patients with abnormal CRT had an increased risk of adverse outcomes (88% vs. 20% p<0.001; RR 4.4 [2.7-7.4]), and hospital mortality (63% vs. 9% p<0.001; RR 6.7 [2.9-16]) as compared to those with normal CRT after FR. Specifically, CRT-normal patients required less frequently mechanical ventilation, renal replacement therapy, and ICU admission, and exhibited a lower hospital mortality.

CONCLUSIONS

Hyperlactatemic sepsis patients with abnormal CRT after initial fluid resuscitation exhibit higher mortality and worse clinical outcomes than patients with normal CRT.

Damage Control Resuscitation for Catastrophic Bleeding

The timely recognition of shock secondary to hemorrhage from severe facial trauma or as a complication of complex oral and maxillofacial surgery presents formidable challenges. Specific hemostatic disorders are induced by hemorrhage and several extreme homeostatic imbalances may appear during or after resuscitation. Damage control resuscitation has evolved from massive transfusion to a more complex therapeutic paradigm that includes hemodynamic resuscitation, hemostatic resuscitation, and homeostatic resuscitation. Definitive control of bleeding is the principal objective of any comprehensive resuscitation scheme for hemorrhagic shock.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

The Role of Permissive and Induced Hypotension in Current Neuroanesthesia Practice

Background

Induced hypotension (IH) had been used for decades in neurosurgery to reduce the risk for intraoperative blood loss and decrease blood replacement. More recently, this method fell out of favor because of concerns for cerebral and other end-organ ischemia and worse treatment outcomes. Other contributing factors to the decline in its popularity include improvements in microsurgical technique, widespread use of endovascular procedures, and advances in blood conservation and transfusion protocols. Permissive hypotension (PH) is still being used occasionally in neurosurgery; however, its role in current anesthesia practice remains unclear. Our objective was to describe contemporary utilization of IH and PH (collectively called PH) in clinical practice among members of the Society for Neuroscience in Anesthesiology and Critical Care (SNACC).

Methods

A questionnaire was developed and distributed among SNACC members that addressed practice patterns related to the use of PH. The responses were analyzed based on the number of individuals who responded to each specific question.

Results

Of 72 respondents, 67.6% reported over 10 years of clinical experience, while 15.5% reported 5–10 years of post-training experience. The respondents admitted to providing anesthesia for 300 (median) neurosurgical cases per year. PH was applied most commonly during open interventions on cerebral aneurysms (50.8%) and arteriovenous malformations (46%). Seventy-three percent of respondents were not aware of any complications in their practice attributable to PH.

Conclusion

PH is still being used in neuroanesthesia practice by some providers. Further research is justified to clarify the risks and benefits of PH in modern neuroanesthesia practice.

Intravenous Fluids in AKI: A Mechanistically Guided Approach

Acute kidney injury (AKI) has been associated with an increased risk of death and morbidity in many clinical scenarios. The prevention and treatment of AKI therefore has been advocated as a high-priority research focus. However, nearly all strategies tested in this setting have failed to prevent or cure AKI and fluid loading remains a cornerstone of preventive and curative treatment of AKI. Concerns have been raised, however, regarding both the efficacy and safety of fluid loading to prevent or reverse AKI. In this review, we address the question of the best use of fluid loading based on current preclinical and clinical data in a mechanistically guided approach. Impacts of fluid resuscitation on renal hemodynamics, from macrocirculation to microcirculation, with physiological end points as well as renal consequences of different fluids available are discussed. Finally, the complex relationship between renal hemodynamics is discussed.

Microcirculatory monitoring in septic patients: Where do we stand?

Microcirculatory alterations play a pivotal role in sepsis-related morbidity and mortality. However, since the microcirculation has been a "black box", current hemodynamic management of septic patients is still guided by macrocirculatory parameters. In the last decades, the development of several technologies has shed some light on microcirculatory evaluation and monitoring, and the possibility of incorporating microcirculatory variables to clinical practice no longer seems to be beyond reach. The present review provides a brief summary of the current technologies for microcirculatory evaluation, and attempts to explore the potential role and benefits of their integration to the resuscitation process in critically ill septic patients.

Stroke volume optimization: the new hemodynamic algorithm

Critical care practices have evolved to rely more on physical assessments for monitoring cardiac output and evaluating fluid volume status because these assessments are less invasive and more convenient to use than is a pulmonary artery catheter. Despite this trend, level of consciousness, central venous pressure, urine output, heart rate, and blood pressure remain assessments that are slow to be changed, potentially misleading, and often manifested as late indications of decreased cardiac output. The hemodynamic optimization strategy called stroke volume optimization might provide a proactive guide for clinicians to optimize a patient's status before late indications of a worsening condition occur. The evidence supporting use of the stroke volume optimization algorithm to treat hypovolemia is increasing. Many of the cardiac output monitor technologies today measure stroke volume, as well as the parameters that comprise stroke volume: preload, afterload, and contractility.

Sepsis and Septic Shock: Lingering Questions

Sepsis and septic shock are major health conditions in the United States, with a high incidence and mortality. The Surviving Sepsis Campaign, which was formed in 2002, formulates guidelines for the management of severe sepsis and septic shock and has actually demonstrated a reduction in mortality with institution of "sepsis bundles." Despite this, some elements of the guidelines have been questioned, and recent data suggest that strict compliance with bundles and protocols may not be necessary. Still, prompt recognition and treatment of sepsis and septic shock remain of utmost importance.

Haemodynamic coherence in perioperative setting

Over the last decade, there has been an increased interest in the use of goal-directed therapy (GDT) in patients undergoing high-risk surgery, and various haemodynamic monitoring tools have been developed to guide perioperative care. Both the complexity of the patient and surgical procedure need to be considered when deciding whether GDT will be beneficial. Ensuring optimum tissue perfusion is paramount in the perioperative period and relies on the coherence between both macrovascular and microvascular circulations. Although global haemodynamic parameters may be optimised with the use of GDT, microvascular impairment can still persist. This review will provide an overview of both haemodynamic optimisation and microvascular assessment in the perioperative period.

Lactate levels and hemodynamic coherence in acute circulatory failure

In this review, the relationship between changes in macrohemodynamics during the development and treatment of acute circulatory failure is discussed in the context of coherence with microcirculation and changes in lactate. In models of circulatory failure, coherence between changes in macrocirculatory and microcirculatory perfusion and coherence with subsequent changes in lactate levels are more or less preserved. However, in patients, particularly those with septic shock, these relationships are much less clear. As many factors influence the effect of circulatory failure and infection on microcirculation and on lactate levels, this should not be surprising. Resuscitation should therefore aim at adequate tissue perfusion where systemic hemodynamics, microcirculatory perfusion parameters, and lactate levels should be used in their relevant context. This results in treating the individual patient as an n = 1 experiment.

[Management of cardiogenic shock: Results from a survey in France and Belgium]

PURPOSE

Physician survey on cardiogenic shock management; recommendations for the management of patients with cardiogenic shock are based mostly on experts' opinion.

METHODS

Overall 1585 emails were sent to "senior" intensive care physicians from France and Belgium from September 2014 to march 2015. Response rate was 10% (157 respondents). Agreement was assessed based on RAND/UCLA methodology.

RESULTS

Continuous monitoring of cardiac output, vascular filling, noninvasive ventilation were deemed appropriate. The use of systematic diuretics and dopamine seemed inappropriate. There was a strong agreement to use dobutamine as inotropic drug in first intention. The use of noradrenaline and adrenaline was considered appropriate. There was a strong agreement to use mechanical circulatory support, in particular extracorporeal life support, in refractory cardiogenic shock. Only 25% of responders felt that there are criteria of refractory cardiogenic shock. Concerning the objectives of systolic, diastolic and mean blood pressure, 95% of the responses were in the range between 70 to 100, 30 to 50, and 55 to 65mmHg, respectively. The target of SvO₂ was between 55% and 75%, and cardiac index between 1.5 and 3L/min/m² for 95% of responders. There was a strong agreement to maintain hemoglobin between 7 and 9.9g/dL.

CONCLUSION

Based on our physician survey, we found an agreement in vascular filling and early enteral nutrition. Dobutamine and noradrenaline should be the preferred drugs, but not dopamine. Mechanical circulatory support (preferably with extracorporeal support) should be restricted to refractory cardiogenic shock. Those responses differed slightly from experts' opinion, available in terms of recommendations.

Cerebral Blood Flow Autoregulation in Sepsis for the Intensivist: Why Its Monitoring May Be the Future of Individualized Care

Cerebral blood flow (CBF) autoregulation maintains consistent blood flow across a range of blood pressures (BPs). Sepsis is a common cause of systemic hypotension and cerebral dysfunction. Guidelines for BP management in sepsis are based on historical concepts of CBF autoregulation that have now evolved with the availability of more precise technology for its measurement. In this article, we provide a narrative review of methods of monitoring CBF autoregulation, the cerebral effects of sepsis, and the current knowledge of CBF autoregulation in sepsis. Current guidelines for BP management in sepsis are based on a goal of maintaining mean arterial pressure (MAP) above the lower limit of CBF autoregulation. Bedside tools are now available to monitor CBF autoregulation continuously. These data reveal that individual BP goals determined from CBF autoregulation monitoring are more variable than previously expected. In patients undergoing cardiac surgery with cardiopulmonary bypass, for example, the lower limit of autoregulation varied between a MAP of 40 to 90 mm Hg. Studies of CBF autoregulation in sepsis suggest patients frequently manifest impaired CBF autoregulation, possibly a result of BP below the lower limit of autoregulation, particularly in early sepsis or with sepsis-associated encephalopathy. This suggests that the present consensus guidelines for BP management in sepsis may expose some patients to both cerebral hypoperfusion and cerebral hyperperfusion, potentially resulting in damage to brain parenchyma. The future use of novel techniques to study and clinically monitor CBF autoregulation could provide insight into the cerebral pathophysiology of sepsis and offer more precise treatments that may improve functional and cognitive outcomes for survivors of sepsis.

The Physiology of Early Goal-Directed Therapy for Sepsis

In 2001, Rivers and colleagues published a randomized controlled trial of early goal-directed therapy (EGDT) for the treatment of sepsis. More than a decade later, it remains a landmark achievement. The study proved the benefits of early aggressive treatment of sepsis. However, many questions remain about specific aspects of the complex EGDT algorithm. Recently, 3 large trials attempted to replicate these results. None of the studies demonstrated a benefit of an EGDT protocol for sepsis. This review explores the physiologic basis of goal-directed therapy, including the hemodynamic targets and the therapeutic interventions. An understanding of the physiologic basis of EGDT helps reconcile the results of the clinical trials.

[Cardiac hemodynamics during shock : Management in daily clinical routine]

In caring for critically ill patients, a sophisticated approach to treating hemodynamic instability in acute circulatory failure is a major concern of modern critical care. Depending on the form of shock-distributive, cardiogenic, hypovolemic or obstructive, with the possibility of overlapping forms of shock-preload, afterload, cardiac output, and contractility are altered in various ways. Modern critical care uses hemodynamic monitoring and bedside echocardiography in addition to clinical evaluation to treat the underlying cause and sequelae of shock. Fluid therapy taking volume responsiveness and need for volume into account, vasopressor therapy taking microcirculatory derangement into account, and therapy using inotropes, sometimes in combination with vasodilators are the cornerstones of critical care treatment in this regard. Preload, afterload, cardiac output, and contractility must thereby be evaluated and treated in a patient- and situation-specific manner.

Postoperative management

Most patients undergoing major aortic surgery have multiple comorbidities and are at high risk of postoperative complications that affect multiple organ systems. Different aortic pathologies and surgical repair techniques have specific impact on the postoperative course. Ischemia-reperfusion injury is the common denominator in aortic surgery and influences the integrity of end-organ function. Common postoperative problems include hemodynamic instability due to the immediate inflammatory response, renal impairment, spinal cord ischemia, respiratory failure with prolonged mechanical ventilation, and gastrointestinal symptoms such as ileus or mesenteric ischemia. Focused care bundles to establish homeostasis and a team working toward an early functional recovery determine the success of effective rehabilitation and outcomes after aortic surgery.

[Hemodynamic monitoring of critically ill patients : Bedside integration of data]

BACKGROUND

Hemodynamic monitoring of critically ill patients is a key issue in intensive care medicine. Indication and application of invasive hemodynamic monitoring is a highly complex matter and requires thorough professional education and training.

MATERIALS AND METHODS

A literature review was performed.

RESULTS

A pragmatic approach can be divided into several steps such as medical history, physical examination, imaging, and laboratory results, which support the primary working diagnosis and allow further clarification of the underlying pathophysiology. Invasive arterial blood pressure and cardiac output measurement as well as components of the functional hemodynamic monitoring help to assess fluid responsiveness and to guide volume loading, diuretic therapy as well as administration of vasoactive or positive inotrope substances.

CONCLUSIONS

All information gathered through medical history, physical examination, imaging, and hemodynamic monitoring help to form an overall picture and should be reevaluated regularly and in individual cases very closely depending on the hemodynamic instability of the patient. Target values are strictly indicative and are not binding taking into account that each patient has its unique pathophysiological profile.

Changes in peripheral perfusion relate to visceral organ perfusion in early septic shock: A pilot study

PURPOSE

To correlate clinical indicators of peripheral perfusion with visceral organ vascular tone in 30 septic shock patients.

MATERIALS AND METHODS

In a prospective pilot study, capillary refill time, the Mottling score, and peripheral temperature were determined within 24, 48, and 72 hours after intensive care unit admission. Simultaneously, pulsatility indices in the liver, spleen, kidneys, and intestines were measured by Doppler ultrasonography. Correlation analyses were calculated, applying an adjusted significance level (P< .0125) to correct for multiple testing.

RESULTS

Significant relationships were observed between the pulsatility index of selected organs and the capillary refill time (intestines: r= 0.325, P= .007), and the Mottling score (kidneys: r= 0.396, P= .006), but not peripheral temperature (all r< 0.14, P> .05). An association over time was observed for the capillary refill time and pulsatility index of the liver (P= .04) and intestines (P= .03) as well as for the Mottling score and the kidneys' pulsatility index (P= .03), but not for peripheral temperature and any visceral organs' pulsatility index.

CONCLUSIONS

Capillary refill time and skin mottling may be correlated with the pulsatility index, a sonographic surrogate of vascular tone, of visceral organs in early septic shock.

Hemodynamic coherence and the rationale for monitoring the microcirculation

This article presents a personal viewpoint of the shortcoming of conventional hemodynamic resuscitation procedures in achieving organ perfusion and tissue oxygenation following conditions of shock and cardiovascular compromise, and why it is important to monitor the microcirculation in such conditions. The article emphasizes that if resuscitation procedures are based on the correction of systemic variables, there must be coherence between the macrocirculation and microcirculation if systemic hemodynamic-driven resuscitation procedures are to be effective in correcting organ perfusion and oxygenation. However, in conditions of inflammation and infection, which often accompany states of shock, vascular regulation and compensatory mechanisms needed to sustain hemodynamic coherence are lost, and the regional circulation and microcirculation remain in shock. We identify four types of microcirculatory alterations underlying the loss of hemodynamic coherence: type 1, heterogeneous microcirculatory flow; type 2, reduced capillary density induced by hemodilution and anemia; type 3, microcirculatory flow reduction caused by vasoconstriction or tamponade; and type 4, tissue edema. These microcirculatory alterations can be observed at the bedside using direct visualization of the sublingual microcirculation with hand-held vital microscopes. Each of these alterations results in oxygen delivery limitation to the tissue cells despite the presence of normalized systemic hemodynamic variables. Based on these concepts, we propose how to optimize the volume of fluid to maximize the oxygen-carrying capacity of the microcirculation to transport oxygen to the tissues.

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

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

Patient survival, predictive factors and disease course of severe sepsis in Czech intensive care units: A multicentre, retrospective, observational study

BACKGROUND

Severe sepsis/septic shock is associated with high mortality. In Central Europe, there is a dearth of information on the prevalence and treatment of severe sepsis. The EPOSS (Data-based Evaluation and Prediction of Outcome in Severe Sepsis) project launched in 2011 was aimed at collecting data on patients with severe sepsis/septic shock.

METHODS

The EPOSS study processes data from the EPOSS project database, and is a retrospective, multicentre, observational study. This included all consecutive patients aged 18 and over who were admitted to participating ICUs from 1 January 2011 to 5 November 2013 and met the inclusion criteria of severe sepsis/septic shock. The primary endpoint was to analyse the relationship between in-hospital mortality (either in ICU or after discharge from ICU) and the type and number of fulfilled diagnostic and treatment interventions during the first 6 h after the diagnosis of severe sepsis/septic shock.

RESULTS

The collected dataset involved 1082 patients meeting the criteria of severe sepsis/septic shock. Following data validation, a final dataset of 897 patients was obtained. The average age of the patient group was 64.7 years; mortality at discharge from EPOSS ICUs was 35.5% and from hospital 40.7%. Of the 10 evaluated diagnostic and treatment interventions within the initial 6 hours of identifying severe sepsis/septic shock (i.e. fulfilment of SSC bundles), four or five diagnostic and treatment interventions were administered to 58.4% patients. Combined diagnostic and treatment interventions associated with the lowest in-hospital mortality were: CVP of ≥8-12 mm Hg & MAP of ≥65 mm Hg & Urine output at ≥0.5 mL/kg/h & Lactate of ≤4.0 mmol/L & Initial lactate measured & Antibiotics in the first hour. Lactate at <4 mmol/L and MAP of ≥65 mm Hg remained statistically significant even after adjustment for patient age and APACHE II score. Statistically significantly increased in-hospital mortality was found in patients admitted from general departments (45.7%) or from other ICUs (41.6%), compared to a lower in-hospital mortality of patients transferred from outpatient clinics (26.5%) or Emergency (38.0%). Severe sepsis/septic shock patients transferred from the department of internal medicine were associated with a higher in-hospital mortality (45.1%) than surgical patients (35.5%).

CONCLUSIONS

The most effective measures associated with the lowest in-hospital mortality in septic shock patients were CVP of ≥8-12 mm Hg, MAP of ≥65 mm Hg, urine output at ≥0.5 mL/kg/h, initial lactate level of ≤4.0 mmol/L and administration of antibiotics within the first hour.

Preferential effects of low volume versus high volume replacement with crystalloid fluid in a hemorrhagic shock model in pigs

Background

Fluid resuscitation is a core stone of hemorrhagic shock therapy, and crystalloid fluids seem to be associated with lower mortality compared to colloids. However, as redistribution starts within minutes, it has been suggested to replace blood loss with a minimum of a three-fold amount of crystalloids. The hypothesis was that in comparison to high volume (HV), a lower crystalloid volume (LV) achieves a favorable coagulation profile and exerts sufficient haemodynamics in the acute phase of resuscitation.

Methods

In 24 anaesthetized pigs, controlled arterial blood loss of 50 % of the estimated blood volume was either (n = 12) replaced with a LV (one-fold) or a HV (three-fold) volume of a balanced, acetated crystalloid solution at room temperature. Hemodynamic parameters, dilution effects and coagulation profile by standard coagulation tests and thromboelastometry at baseline and after resuscitation were determined in both groups.

Results

LV resuscitation increased MAP significantly less compared to the HV, 61 ± 7 vs. 82 ± 14 mmHg (p < 0.001) respectively, with no difference between lactate and base excess between groups. Haematocrit after fluid replacement was 0.20 vs. 0.16 (LV vs. HV, p < 0.001), suggesting a grade of blood dilution of 32 vs. 42 % (p < 0.001) compared to baseline values. Compared to LV, HV resulted in decreased core temperature (37.5 ± 0.2 vs. 36.0 ± 0.6 °C, p < 0.001), lower platelet count (318 ± 77 vs. 231 ± 53 K/μL, p < 0.01) and lower plasma fibrinogen levels (205 ± 19 vs. 168 ± 24 mg/dL, p < 0.001). Thromboelastometric measurements showed a significant impairment on viscoelastic clot properties following HV group. While prothrombin time index decreased significantly more in the HV group, activated partial thromboplastin time did not differ between both groups. HV did not result in hyperchloraemic acidosis.

Discussion

Coagulation parameters represented by plasma fibrinogen and ROTEM parameters were also less impaired with LV. With regrad to hematocrit, 60 % of LV remained intracascular , while in HV only 30 % remained in circulation within the first hour of administration. In the acute setting of 50 % controlled blood loss, a one fold LV crystalloid replacement strategy is sufficient to adequately raise blood pressure up to a mean arterial pressure >50 mm Hg. The concept of damage control resuscitation (DCR) with permissive hypotension may be better met by using LV as compared to a three fold HV resuscitation strategy.

Conclusion

High volume administration of an acetated balanced crystalloid does not lead to hyperchloraemic acidosis, but may negatively influence clinical parameters, such as higher blood pressure, lower body temperature and impaired coagulation parameters, which could potentially increase bleeding after trauma. Replacement of acute blood loss with just an equal amount of an acetated balanced crystalloid appears to be the preferential treatment strategy in the acute phase after controlled bleeding.