How to choose the therapeutic goals to improve tissue perfusion in septic shock

Jehovah's Witness Needing Critical Care: A Narrative Review on the Expanding Arsenal

Present day Jehovah's Witness (JW) religion accounts for 8.5 million followers. A tenant feature of the JW faith is religious objection to transfusions of blood and blood products. Interpatient variability, as it pertains to blood and blood products may occur; hence, a confidential interview will determine which products individual may consent to (Marsh and Bevan, 2002). This belief and practice place great restrictions on treating medical professionals in scenarios of life-threatening anaemia and active haemorrhage. The review to follow explores the physiological and pathophysiological consequences of severe anaemia. Non-blood transfusion practices are explored, many of which are potentially lifesaving. Particular attention is drawn to the evolving science involving artificial oxygen carriers and their use in emergency situations. A greater safety profile ensures its future use amongst religious objectors to be greatly beneficial. Intravenous iron supplementation has enjoyed a lively debate within the critical care community. A review of recent systematic and meta-analysis supports its use in the ICU; however, more investigation is needed into the complementary use of hepcidin.

IMPACT OF HIGH-DOSE VASOPRESSOR DURING ENDOTOXIC SHOCK ON THE CEREBRAL, LINGUAL, HEPATIC, AND RENAL MICROCIRCULATION EVALUATED BY NEAR-INFRARED SPECTROSCOPY IN SWINE

ABSTRACT

Background: High-dose vasopressors maintain blood pressure during septic shock but may adversely reduce microcirculation in vital organs. We assessed the effect of high-dose norepinephrine and vasopressin on the microcirculation of the brain, tongue, liver, and kidney during endotoxic shock using near-infrared spectroscopy (NIRS). Methods: Thirteen pigs (24.5 ± 1.8 kg) were anesthetized, and an NIRS probe was attached directly to each organ. Approximately 0.2, 0.5, 1, and 2 μg/kg/min of norepinephrine were administered in a stepwise manner, followed by 0.5, 1, 2, and 5 μg/kg/min of sodium nitroprusside in normal condition. Moreover, 1 μg/kg/h of lipopolysaccharide was administered continuously after 100 μg bolus to create endotoxic shock and after 1,000 mL of crystalloid infusion and high-dose norepinephrine (2, 5, 10, and 20 μg/kg/min) and vasopressin (0.6, 1.5, 3, and 6 U/min) were administered in a stepwise manner. The relationship between the MAP and each tissue oxygenation index (TOI) during vasopressor infusion was evaluated. Results: Three pigs died after receiving lipopolysaccharides, and 10 were analyzed. An increase of >20% from the baseline MAP induced by high-dose norepinephrine during endotoxic shock reduced the TOI in all organs except the liver. The elevation of MAP to baseline with vasopressin alone increased the kidney and liver TOIs and decreased the tongue TOI. Conclusion: Forced blood pressure elevation with high-dose norepinephrine during endotoxic shock decreased the microcirculation of vital organs, especially the kidney. Cerebral TOI may be useful for identifying the upper limit of blood pressure, at which norepinephrine impairs microcirculation.

Effect of methylene blue on hemodynamic and metabolic response in septic shock patients

INTRODUCTION

Septic shock is a lethal disease responsible for a large proportion of deaths in the Intensive Care Unit (ICU), even with therapy centered on fluid resuscitation, use of vasopressors and empirical antibiotic therapy applied within the first hour of diagnosis. Considering the multifactorial pathophysiology of septic shock and the mechanism of action of vasopressors, some patients may not respond adequately, which can lead to the maintenance of vasodilatation, hypotension and increased morbidity, and mortality. This protocol aims to verify whether the use of methylene blue in septic patients with an early diagnosis can contribute to an earlier resolution of a shock compared to standard treatment.

METHODS AND ANALYSIS

This is a study protocol for a single-center randomized clinical trial design in an ICU of a tertiary university hospital. In this study, we intend to include 64 patients aged between 18 and 80 years with a diagnosis of septic shock, of any etiology, with up to 72 hours of evolution after volume restoration, using norepinephrine at a dose ≥0.2 μg/kg/min and vasopressin at a dose of 0.04 IU/min. After the initial approach, we will randomize patients into two groups, standard care, and standard care plus methylene blue. The sample size was calculated in order to show 30% differences in septic shock resolution between groups. The Research Ethics Committee approved the study, and all patients included will sign an informed consent form (Clinical registration: RBR-96584w4).

Gunanti Soeyono DV, Bardosono S, Jusman S, Siagian M, Lubis M. Resuscitation of hemorrhagic shock using normal saline does not damage the glycocalyx in the immediate resuscitation phase

OBJECTIVES:

The objectives were to study the effect of aggressive resuscitation using normal saline on hemodynamics, serum atrial natriuretic peptide (ANP), syndecan-1 (marker of endothelial glycocalyx shedding), and extravascular lung water index (ELWI) following hemorrhagic shock.

METHODS:

Eleven male piglets (Sus scrofa) underwent blood drawing to create 20% drop in mean arterial pressure (MAP). Two-phase resuscitation was performed: Phase 1 using normal saline of an equal volume of blood drawn to create shock and Phase 2 using 40 ml/kg BW of normal saline to simulate hypervolemia and hemodilution. Heart rate, MAP, cardiac index (CI), systemic vascular resistance index, oxygen delivery (DO₂), global end-diastolic volume index, ELWI, hemoglobin (Hb), lactate, ANP, and syndecan-1 at each phase and up to 60 min following Phase 2 resuscitation were recorded.

RESULTS:

Phase 2 resuscitation significantly decreased Hb concentration (P = 0.006), however, DO₂ was maintained (P = 1.000). CI increased from shock to Phase 1 (P = 0.029) and further increase in Phase 2 resuscitation (P = 0.001). Overall, there was a transient increase of ANP following Phase 1 resuscitation, from 85.20 ± 40.86 ng/L at baseline to 106.42 ± 33.71 ng/L (P = 0.260). Serum syndecan-1 and ELWI change at all phases were not significant.

CONCLUSIONS:

We demonstrate compensatory protective mechanism despite overzealous fluid resuscitation. Compensatory increased CI despite decreased Hb maintained DO₂. In the absence of inflammation, serum ANP did not increase significantly, no glycocalyx shedding occurred, subsequently no change in ELWI. We show that factors other than volume overload are more dominant in causing glycocalyx shedding.

Monitoring peripheral perfusion in sepsis associated acute kidney injury: Analysis of mortality

Microcirculatory disorders have been consistently linked to the pathophysiology of sepsis. One of the major organs affected is the kidneys, resulting in sepsis-associated acute kidney injury (SA-AKI) that correlates considerably with mortality. However, the potential role of clinical assessment of peripheral perfusion as a possible tool for SA-AKI management has not been established. To address this gap, the purpose of this study was to investigate the prevalence of peripheral hypoperfusion in SA-AKI, its association with mortality, and fluid balance. This observational cohort study enrolled consecutive septic patients in the Intensive Care Unit. After fluid resuscitation, peripheral perfusion was evaluated using the capillary filling time (CRT) and peripheral perfusion index (PI) techniques. The AKI was defined based on both serum creatinine and urine output criteria. One hundred and forty-one patients were included, 28 (19%) in the non-SA-AKI group, and 113 (81%) in the SA-AKI group. The study revealed higher peripheral hypoperfusion rates in the SA-AKI group using the CRT (OR 3.6; 95% CI 1.35-9.55; p < 0.05). However, this result lost significance after multivariate adjustment. Perfusion abnormalities in the SA-AKI group diagnosed by both CRT (RR 1.96; 95% CI 1.25-3.08) and PI (RR 1.98; 95% CI 1.37-2.86) methods were associated to higher rates of 28-day mortality (p < 0.01). The PI's temporal analysis showed a high predictive value for death over the first 72 h (p < 0.01). A weak correlation between PI values and the fluid balance was found over the first 24 h (r = - 0.20; p < 0.05). In conclusion, peripheral perfusion was not different intrinsically between patients with or without SA-AKI. The presence of peripheral hypoperfusion in the SA-AKI group has appeared to be a prognostic marker for mortality. This evaluation maintained its predictive value over the first 72 hours. The fluid balance possibly negatively influences peripheral perfusion in the SA-AKI.

Effect of Increasing Blood Pressure With Noradrenaline on the Microcirculation of Patients With Septic Shock and Previous Arterial Hypertension

OBJECTIVES

To assess whether an increase in mean arterial pressure in patients with septic shock and previous systemic arterial hypertension changes microcirculatory and systemic hemodynamic variables compared with patients without arterial hypertension (control).

DESIGN

Prospective, nonblinded, interventional study.

SETTING

Three ICUs in two teaching hospitals.

PATIENTS

After informed consent, we included patients older than 18 years with septic shock for at least 6 hours, sedated, and under mechanical ventilation. We paired patients with and without arterial hypertension by age.

INTERVENTIONS

After obtaining systemic and microcirculation baseline hemodynamic variables (time 0), we increased noradrenaline dose to elevate mean arterial pressure up to 85-90 mm Hg before collecting a new set of measurements (time 1).

MEASUREMENTS AND MAIN RESULTS

We included 40 patients (20 in each group). There was no significant difference in age between the groups. After the rise in mean arterial pressure, there was a significant increase in cardiac index and a slight but significant reduction in lactate in both groups. We observed a significant improvement in the proportion of perfused vessels (control: 57.2 ± 14% to 66 ± 14.8%; arterial hypertension: 61.4 ± 12.3% to 70.8 ± 7.1%; groups: p = 0.29; T0 and T1: p < 0.001; group and time interaction: p = 0.85); perfused vessels density (control: 15.6 ± 4 mm/mm to 18.6 ± 4.5 mm/mm; arterial hypertension: 16.4 ± 3.5 mm/mm to 19.1 ± 3 mm/mm; groups: p = 0.51; T0 and T1: p < 0.001; group and time interaction: p = 0.70), and microcirculatory flow index (control: 2.1 ± 0.6 to 2.4 ± 0.6; arterial hypertension: 2.1 ± 0.5 to 2.6 ± 0.2; groups: p = 0.71; T0 and T1: p = 0.002; group and time interaction: p = 0.45) in both groups.

CONCLUSIONS

Increasing mean arterial pressure with noradrenaline in septic shock patients improves density and flow in small vessels of sublingual microcirculation. However, this improvement occurs both in patients with previous arterial hypertension and in those without arterial hypertension.

[Association between peripheral perfusion, microcirculation and mortality in sepsis: a systematic review]

Although increasing evidence supports the monitoring of peripheral perfusion in septic patients, no systematic review has been undertaken to explore the strength of association between poor perfusion assessed in microcirculation of peripheral tissues and mortality. A search of the most important databases was carried out to find articles published until February 2018 that met the criteria of this study using different keywords: sepsis, mortality, prognosis, microcirculation and peripheral perfusion. The inclusion criteria were studies that assessed association between peripheral perfusion/microcirculation and mortality in sepsis. The exclusion criteria adopted were: review articles, animal/pre-clinical studies, meta-analyzes, abstracts, annals of congress, editorials, letters, case-reports, duplicate and articles that did not present abstracts and/or had no text. In the 26 articles were chosen in which 2465 patients with sepsis were evaluated using at least one recognized method for monitoring peripheral perfusion. The review demonstrated a heterogeneous critically ill group with a mortality-rate between 3% and 71% (median=37% [28%-43%]). The most commonly used methods for measurement were Near-Infrared Spectroscopy (NIRS) (7 articles) and Sidestream Dark-Field (SDF) imaging (5 articles). The vascular bed most studied was the sublingual/buccal microcirculation (8 articles), followed by fingertip (4 articles). The majority of the studies (23 articles) demonstrated a clear relationship between poor peripheral perfusion and mortality. In conclusion, the diagnosis of hypoperfusion/microcirculatory abnormalities in peripheral non-vital organs was associated with increased mortality. However, additional studies must be undertaken to verify if this association can be considered a marker of the gravity or a trigger factor for organ failure in sepsis.