Effects of epinephrine, norepinephrine, and phenylephrine on microcirculatory blood flow in the gastrointestinal tract in sepsis*

Considerations for medical nutrition therapy management of the critically ill patient with hematological malignancies: A narrative review

Patients with hematological malignancies (HMs) are more frequently admitted now than in the past to the intensive care unit (ICU) due to more aggressive approaches in primary therapy of HMs and the need for critical care support. Pathophysiological alterations derived from HMs and the different hematological therapies, such as chemotherapy, negatively affect gastrointestinal (GI) function, metabolism, and nutrition status. Further, malnutrition strongly influences outcomes and tolerance of the different hematological therapies. In consequence, these critically ill patients frequently present with malnutrition and pathophysiological alterations that create challenges for the delivery of medical nutrition therapy (MNT) in the ICU. Frequent screening, gauging tolerance, and monitoring nutrition status are mandatory to provide individualized MNT and achieve nutrition objectives. The present review discusses how HM impact GI function and nutrition status, the importance of MNT in patients with HM, and specific considerations for guidance in providing adequate MNT to these patients when admitted to the ICU.

Risk factors for postoperative acute pancreatitis after thoracic aortic surgery

BACKGROUND

We aimed to investigate the incidence and risk factors of postoperative acute pancreatitis (PAP) following thoracic aortic surgery with circulatory arrest.

METHODS

One hundred fifty-two patients who underwent thoracic aortic surgery with circulatory arrest between February 2015 and March 2023 were retrospectively reviewed. Postoperative acute pancreatitis was defined as the presence of two or more of the following criteria: (1) abdominal pain, (2) postoperative amylase or lipase levels greater than three times the upper limit of normal, and (3) evidence of pancreatitis on postoperative computed tomography (CT) scan. Univariate and multivariate analyses were performed to find risk factors for PAP.

RESULTS

Nine patients (5.9%) developed PAP without mortality. All of the nine patients had elevated pancreatic enzymes and evidence of pancreatitis on CT. They improved with conservative therapy. In multivariate analysis, only cross-clamp time was found to be a significant risk factor for PAP (adjusted odds ratio, 1.04; 95% confidence interval, 1-1.08; p = 0.042).

CONCLUSION

The incidence of PAP after thoracic aortic surgery with circulatory arrest was 5.9%, and cross-clamp time is an independent risk factor for PAP.

Amiodarone Administration during Cardiopulmonary Resuscitation Is Not Associated with Changes in Short-Term Mortality or Neurological Outcomes in Cardiac Arrest Patients with Shockable Rhythms

Background: The search for the best therapeutic approach in cardiopulmonary resuscitations (CPR) remains open to question. In this study, we evaluated if Amiodarone administration during CPR was associated with short-term mortality or neurological development. Methods: A total of 232 patients with sudden cardiac arrest (CA) with shockable rhythms were included in our analysis. Propensity score matching based on age, gender, type of CA, and CPR duration was used to stratify between patients with and without Amiodarone during CPR. Primary endpoints were short-term mortality (30-day) and neurological outcomes assessed by the cerebral performance category. Secondary endpoints were plasma lactate, phosphate levels at hospital admission, and the peak Neuron-specific enolase. Results: Propensity score matching was successful with a caliper size used for matching of 0.089 and a sample size of n = 82 per group. The 30-day mortality rates were similar between both groups (p = 0.24). There were no significant differences in lactate levels at hospital admission and during the following five days between the groups. Patients receiving Amiodarone showed slightly higher phosphate levels at hospital admission, while the levels decreased to a similar value during the following days. Among CA survivors to hospital discharge, no differences between the proportion of good neurological outcomes were detected between the two groups (p = 0.58), despite slightly higher peak neuron-specific enolase levels in CA patients receiving Amiodarone (p = 0.03). Conclusions: Amiodarone administration is not associated with short-term mortality or neurological outcomes in CA patients with shockable rhythms receiving CPR.

When can we start early enteral nutrition safely in patients with shock on vasopressors?

Shock is a common critical illness characterized by microcirculatory disorders and insufficient tissue perfusion. Patients with shock and hemodynamic instability generally require vasopressors to maintain the target mean arterial pressure. Enteral nutrition (EN) is an important therapeutic intervention in critically ill patients and has unique benefits for intestinal recovery. However, the initiation of early EN in patients with shock receiving vasopressors remains controversial. Current guidelines make conservative and vague recommendations regarding early EN support in patients with shock. Increasing studies demonstrates that early EN delivery is safe and feasible in patients with shock receiving vasopressors; however, this evidence is based on observational studies. Changes in gastrointestinal blood flow vary by vasopressor and inotrope and are complex. The risk of gastrointestinal complications, especially the life-threatening complications of non-occlusive mesenteric ischemia and non-occlusive bowel necrosis, cannot be ignored in patients with shock during early EN support. It remains a therapeutic challenge in critical care nutrition therapy to determine the initiation time of EN in patients with shock receiving vasopressors and the safe threshold region for initiating EN with vasopressors. Therefore, the current review aimed to summarize the evidence on the optimal and safe timing of early EN initiation in patients with shock receiving vasopressors to improve clinical practice.

Raising Systemic Blood Pressure to Delay Irreversible Intestinal Ischemia in a Swine Model of Proximal Superior Mesenteric ArteryOcclusion

INTRODUCTION

Acute proximal superior mesenteric artery (SMA) occlusion is highly lethal, and adjuncts are needed to mitigate ischemic injury until definitive therapy. We hypothesized that raising mean arterial pressure (MAP) >90 mmHg with norepinephrine may delay irreversible bowel ischemia by increasing gastroduodenal artery (GDA) flow despite possible pressor-induced vasospasm.

METHODS

12 anesthetized swine underwent laparotomy, GDA flow probe placement, and proximal SMA exposure and clamping. Animals were randomized between conventional therapy (CT) versus targeted MAP >90 mmHg (MAP push; MP) where norepinephrine was titrated after 45 min of SMA occlusion. Animals were followed until bowel death or 4 h. Kaplan-Meier bowel survival, mean normalized GDA flow, and histology were compared.

RESULTS

12 swine (mean 57.8 ± 7.6 kgs) were included, six per group. Baseline weight, HR, MAP and GDA flows were not different. Within 5 min following SMA clamping, all 12 animals had an increase in MAP without other intervention from 81.7 to 105.5 mmHg (29.1%, P < 0.01) with a concomitant 74.9% increase in GDA flow as compared to baseline (P < 0.01). Beyond 45 min postclamp, MAP was greater in the MP group as intended, as were GDA flows. Median time to irreversibly ischemic bowel was 31% longer for MAP push animals (CT: 178 versus MP: 233 min, P = 0.006), Hazard Ratio of CT 8.85 (95% CI: 1.86-42.06); 3/6 MP animals versus 0/6 CT animals with bowel survived to predetermined end point.

CONCLUSIONS

In this swine model of acute complete proximal SMA occlusion, increasing MAP >90 mmHg with norepinephrine was associated with an increase in macrovascular blood flow through the GDA and bowel survival. Norepinephrine was not associated with worse bowel survival and a MAP push may increase the time window where ischemic bowel can be salvaged.

Intestinal Ischemia - Etiology and Foundational Concepts

Intestinal Ischemia: Etiology and Foundational ConceptsThe authors provide an overview of the intestinal anatomy and the pathophysiology and etiology of intestinal ischemia.

Effects of phenylephrine on systemic and cerebral circulations in humans: a systematic review with mechanistic explanations

We conducted a systematic review of the literature reporting phenylephrine-induced changes in blood pressure, cardiac output, cerebral blood flow and cerebral tissue oxygen saturation as measured by near-infrared spectroscopy in humans. We used the proportion change of the group mean values reported by the original studies in our analysis. Phenylephrine elevates blood pressure whilst concurrently inducing a reduction in cardiac output. Furthermore, despite increasing cerebral blood flow, it decreases cerebral tissue oxygen saturation. The extent of phenylephrine's influence on cardiac output (r = -0.54 and p = 0.09 in awake humans; r = -0.55 and p = 0.007 in anaesthetised humans), cerebral blood flow (r = 0.65 and p = 0.002 in awake humans; r = 0.80 and p = 0.003 in anaesthetised humans) and cerebral tissue oxygen saturation (r = -0.72 and p = 0.03 in awake humans; r = -0.24 and p = 0.48 in anaesthetised humans) appears closely linked to the magnitude of phenylephrine-induced blood pressure changes. When comparing the effects of phenylephrine in awake and anaesthetised humans, we found no evidence of a significant difference in cardiac output, cerebral blood flow or cerebral tissue oxygen saturation. There was also no evidence of a significant difference in effect on systemic and cerebral circulations whether phenylephrine was given by bolus or infusion. We explore the underlying mechanisms driving the phenylephrine-induced cardiac output reduction, cerebral blood flow increase and cerebral tissue oxygen saturation decrease. Individualised treatment approaches, close monitoring and consideration of potential risks and benefits remain vital to the safe and effective use of phenylephrine in acute care.

Giant Pancreatic Pseudocyst after Coronary Artery Bypass Graft in a Hemodialysis Patient: A Case Report

End-stage renal disease (ESRD) patients have a high prevalence of coronary artery disease, and coronary artery bypass graft (CABG) is one of the essential treatments. ESRD patients undergoing CABG surgery have an increased risk of postoperative complications, including acute pancreatitis. Here, we present the unique case of an exceptionally large pancreatic pseudocyst caused by pancreatitis in an ESRD patient after CABG surgery. A 45-year-old male with ESRD under maintenance hemodialysis received CABG surgery for significant coronary artery disease. Two weeks later, he experienced worsening abdominal pain and a palpable mass was noticed in the epigastric region. Computer tomography revealed an unusually large pseudocyst measuring 21 × 17 cm in the retroperitoneum due to necrotizing pancreatitis. The patient underwent percutaneous cystic drainage, and the symptoms were significantly improved without surgical intervention. Factors such as prolonged cardiopulmonary bypass time, postoperative hypotension, and intradialytic hypotension appeared to have contributed to the development of severe pancreatitis in this case. This report highlights the rarity of a giant pancreatic pseudocyst in an ESRD patient after CABG surgery and emphasizes the importance of vigilant postoperative care.

Immediate Norepinephrine in Endotoxic Shock: Effects on Regional and Microcirculatory Flow

OBJECTIVES

To investigate the effects of immediate start of norepinephrine versus initial fluid loading followed by norepinephrine on macro hemodynamics, regional splanchnic and intestinal microcirculatory flows in endotoxic shock.

DESIGN

Animal experimental study.

SETTING

University translational research laboratory.

SUBJECTS

Fifteen Landrace pigs.

INTERVENTIONS

Shock was induced by escalating dose of lipopolysaccharide. Animals were allocated to immediate start of norepinephrine (i-NE) ( n = 6) versus mandatory 1-hour fluid loading (30 mL/kg) followed by norepinephrine (i-FL) ( n = 6). Once mean arterial pressure greater than or equal to 75 mm Hg was, respectively, achieved, successive mini-fluid boluses of 4 mL/kg of Ringer Lactate were given whenever: a) arterial lactate greater than 2.0 mmol/L or decrease less than 10% per 30 min and b) fluid responsiveness was judged to be positive. Three additional animals were used as controls (Sham) ( n = 3). Time × group interactions were evaluated by repeated-measures analysis of variance.

MEASUREMENTS AND MAIN RESULTS

Hypotension was significantly shorter in i-NE group (7.5 min [5.5-22.0 min] vs 49.3 min [29.5-60.0 min]; p < 0.001). Regional mesenteric and microcirculatory flows at jejunal mucosa and serosa were significantly higher in i-NE group at 4 and 6 hours after initiation of therapy ( p = 0.011, p = 0.032, and p = 0.017, respectively). Misdistribution of intestinal microcirculatory blood flow at the onset of shock was significantly reversed in i-NE group ( p < 0.001), which agreed with dynamic changes in mesenteric-lactate levels ( p = 0.01) and venous-to-arterial carbon dioxide differences ( p = 0.001). Animals allocated to i-NE showed significantly higher global end-diastolic volumes ( p = 0.015) and required significantly less resuscitation fluids ( p < 0.001) and lower doses of norepinephrine ( p = 0.001) at the end of the experiment. Pulmonary vascular permeability and extravascular lung water indexes were significantly lower in i-NE group ( p = 0.021 and p = 0.004, respectively).

CONCLUSIONS

In endotoxemic shock, immediate start of norepinephrine significantly improved regional splanchnic and intestinal microcirculatory flows when compared with mandatory fixed-dose fluid loading preceding norepinephrine. Immediate norepinephrine strategy was related with less resuscitation fluids and lower vasopressor doses at the end of the experiment.

Running from a Bear: How We Teach Vasopressors, Adrenoreceptors, and Shock

Vasopressors are widely used in the management of shock among critically ill patients. The physiology of vasopressors and adrenoreceptors and their effects on end organs therefore represent important, high-yield topics for learners in the critical care environment. In this report, we describe our approach to teaching this core concept using the stereotypical human physiologic response when running from a bear, in the context of the relevant supporting literature. We use escaping from a threatening predator as a lens to describe the end-organ effects of activating adrenoreceptors together with the effects of endogenous and exogenous catecholamines and vasopressors. After reviewing this foundational physiology, we transition to the clinical environment, reviewing the pathophysiology of various shock states. We then consolidate our teaching by integrating the physiology of adrenoreceptors with the pathophysiology of shock to understand the appropriateness of each therapy to various shock phenotypes. We emphasize to learners the importance of generating a hypothesis about a patient's physiology, testing that hypothesis with an intervention, and then revising the hypothesis as needed, a critical component in the management of critically ill patients.

Management of Hemorrhagic Shock: Physiology Approach, Timing and Strategies

Hemorrhagic shock (HS) management is based on a timely, rapid, definitive source control of bleeding/s and on blood loss replacement. Stopping the hemorrhage from progressing from any named and visible vessel is the main stem fundamental praxis of efficacy and effectiveness and an essential, obligatory, life-saving step. Blood loss replacement serves the purpose of preventing ischemia/reperfusion toxemia and optimizing tissue oxygenation and microcirculation dynamics. The "physiological classification of HS" dictates the timely management and suits the 'titrated hypotensive resuscitation' tactics and the 'damage control surgery' strategy. In any hypotensive but not yet critical shock, the body's response to a fluid load test determines the cut-off point between compensation and progression between the time for adopting conservative treatment and preparing for surgery or rushing to the theater for rapid bleeding source control. Up to 20% of the total blood volume is given to refill the unstressed venous return volume. In any critical level of shock where, ab initio, the patient manifests signs indicating critical physiology and impending cardiac arrest or cardiovascular accident, the balance between the life-saving reflexes stretched to the maximum and the insufficient distal perfusion (blood, oxygen, and substrates) remains in a liable and delicate equilibrium, susceptible to any minimal change or interfering variable. In a cardiac arrest by exsanguination, the core of the physiological issue remains the rapid restoration of a sufficient venous return, allowing the heart to pump it back into systemic circulation either by open massage via sternotomy or anterolateral thoracotomy or spontaneously after aorta clamping in the chest or in the abdomen at the epigastrium under extracorporeal resuscitation and induced hypothermia. This is the only way to prevent ischemic damage to the brain and the heart. This is accomplishable rapidly and efficiently only by a direct approach, which is a crush laparotomy if the bleeding is coming from an abdominal +/- lower limb site or rapid sternotomy/anterolateral thoracotomy if the bleeding is coming from a chest +/- upper limbs site. Without first stopping the bleeding and refilling the heart, any further exercise is doomed to failure. Direct source control via laparotomy/thoracotomy, with the concomitant or soon following venous refilling, are the two essential, initial life-saving steps.

Updates in the Management of Perioperative Vasoplegic Syndrome

Vasoplegic syndrome occurs relatively frequently in cardiac surgery, liver transplant, major noncardiac surgery, in post-return of spontaneous circulation situations, and in pateints with sepsis. It is paramount for the anesthesiologist to understand both the pathophysiology of vasoplegia and the different treatment strategies available for rescuing a patient from life-threatening hypotension.

Severe gastrointestinal injury associated with SARS-CoV-2 infection: Thrombosis or Inflammation?: A retrospective case series study

OBJECTIVES

Acute gastrointestinal injury (AGI) associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has a low incidence of complications in patients admitted to the intensive care unit (ICU). Pathophysiological knowledge related to AGI is limited, as few studies have been published on this topic. Therefore, this study was carried out to identify the clinical and histopathological features of patients with SARS-CoV-2 infection and grade IV AGI.

METHODS

This is a retrospective case study of fifteen patients with SARS-CoV-2 infection and grade IV AGI who underwent emergency surgery.

RESULTS

This study revealed a mortality rate of 62.5%. The most frequent gastrointestinal symptoms were abdominal distension (100%) and increased gastric residual volume (93.3%). Distended bowel loops on plain abdominal radiography (90%) and intestinal pneumatosis on computed tomography (50%) were the most frequent imaging findings. Surgical exploration revealed intestinal ischemia (66.6%) and necrosis (46.6%), and histopathology showed ischemic and liquefactive necrosis with mixed inflammatory involvement and absence of thrombosis as the cause of AGI.

CONCLUSIONS

AGI associated with severe SARS-CoV-2 infection has a high mortality rate and poses a diagnostic challenge in the ICU. The complex pathophysiology and histopathological findings indicate an associated inflammatory phenomenon as the main alteration in the absence of thrombosis, as per the intestinal biopsies of the cases studied. Further clinical studies are required to gain a better understanding of this pathology.

Administration of enteral nutrition and gastrointestinal complications in Covid-19 critical patients in prone position

Background

The prone position (PP) used in the treatment of critically ill patients infected with SARS-CoV-2, may be a barrier to enteral nutrition (EN). This study aimed to analyze the effectiveness and complications of EN in the PP, as well as clinical outcomes.

Methods

Prospective cohort study with patients in EN and coronavirus disease 2019 (COVID-19), on mechanical ventilation (MV), which whom needed or not PP. Gastrointestinal intolerances (GII) related to PP were evaluated, and correlated with possible confounding factors. EN, days on MV, Intensive Care Unit (ICU) length of stay, hospital length of stay, ventilator-associated pneumonia (VAP) and mortality were analyzed. The data were evaluated daily and compared prone group (PG=57) and supine group (SG=69).

Results

The PP was associated with GII (P=0.000) and presented in 32 patients (26,44%) with no difference among groups. Association between epinephrine (P=0.003), vasopressin (P=0.018), and GII was observed. There was no difference between the total volume of enteral nutrition (TVEN) infused in the groups. However, the mean EN infused for the days when the patient was on PP was (70.0% ± 31.5) and for the days in supine position was (74.8% ± 27.3), P= 0.006. The PG had a longer time on MV (P=0.005) and ICU (P=0.003) and PP was associated with VAP (P=<0.001). The infused TVEN showed no association with VAP (P=0.09).

Conclusion

PP was a determining factor in GII and proved to be a risk factor for VAP, but the EN protocol seems to have ensured an adequate EN supply in PP and be a safe alternative.

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

Background and purpose

To date, sepsis remains the main cause of mortality in intensive care units (ICU). This study aimed analyze the risk factors of the prognosis in sepsis patients.

Methods

In this case-control study, patients with sepsis admitted to the intensive care unit of a Chinese hospital between January and November 2020 were analyzed. Ultrasound and clinical data were analyzed and compared between non-survivors and survivors. The ROC curve analysis was also performed to determine the best indicator for predicting mortality.

Results

A total of 72 patients with sepsis in ICU were included for analysis. The basic characteristics between the survivals and non-survivals were similar, except for acute physiology and chronic health evaluation (APACHE) Ⅱ score, sepsis-related organ failure assessment (SOFA) score, lactate level, ultrasound parameters from superior mesenteric artery (SMA) such as peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI). Univariate analysis revealed that the APACHE Ⅱ score, SOFA score, lactate, low PSV, EDV, and RI were potential risk factors for mortality in sepsis, while multivariate analysis suggested that low PSV was an independent risk factor for mortality, and the adjusted odds ratio was 0.295 (95% CI: 0.094–0.925). The ROC analysis showed that the PSV (AUC = 0.99; sensitivity and specificity were 0.99 and 0.96, respectively) had good predictive value for mortality in sepsis.

Conclusion

Low PSV as found to be an independent risk factor and good predictor for mortality in patients with sepsis. This study shows the promise of ultrasound in predicting mortality in patients with sepsis; however, further studies are needed to validate these results.

Alternatives to norepinephrine in septic shock: Which agents and when?

Vasopressors are the cornerstone of hemodynamic management in patients with septic shock. Norepinephrine is currently recommended as the first-line vasopressor in these patients. In addition to norepinephrine, there are many other potent vasopressors with specific properties and/or advantages that act on vessels through different pathways after activation of specific receptors; these could be of interest in patients with septic shock. Dopamine is no longer recommended in patients with septic shock because its use is associated with a higher rate of cardiac arrhythmias without any benefit in terms of mortality or organ dysfunction. Epinephrine is currently considered as a second-line vasopressor therapy, because of the higher rate of associated metabolic and cardiac adverse effects compared with norepinephrine; however, it may be considered in settings where norepinephrine is unavailable or in patients with refractory septic shock and myocardial dysfunction. Owing to its potential effects on mortality and renal function and its norepinephrine-sparing effect, vasopressin is recommended as second-line vasopressor therapy instead of norepinephrine dose escalation in patients with septic shock and persistent arterial hypotension. However, two synthetic analogs of vasopressin, namely, terlipressin and selepressin, have not yet been employed in the management of patients with septic shock, as their use is associated with a higher rate of digital ischemia. Finally, angiotensin Ⅱ also appears to be a promising vasopressor in patients with septic shock, especially in the most severe cases and/or in patients with acute kidney injury requiring renal replacement therapy. Nevertheless, due to limited evidence and concerns regarding safety (which remains unclear because of potential adverse effects related to its marked vasopressor activity), angiotensin Ⅱ is currently not recommended in patients with septic shock. Further studies are needed to better define the role of these vasopressors in the management of these patients.

Vasopressors and Risk of Acute Mesenteric Ischemia: A Worldwide Pharmacovigilance Analysis and Comprehensive Literature Review

Vasodilatory shock, such as septic shock, requires personalized management which include adequate fluid therapy and vasopressor treatments. While these potent drugs are numerous, they all aim to counterbalance the vasodilatory effects of a systemic inflammatory response syndrome. Their specific receptors include α- and β-adrenergic receptors, arginine-vasopressin receptors, angiotensin II receptors and dopamine receptors. Consequently, these may be associated with severe adverse effects, including acute mesenteric ischemia (AMI). As the risk of AMI depends on drug class, we aimed to review the evidence of plausible associations by performing a worldwide pharmacovigilance analysis based on the World Health Organization database, VigiBase®. Among 24 million reports, 104 AMI events were reported, and disproportionality analyses yielded significant association with all vasopressors, to the exception of selepressin. Furthermore, in a comprehensive literature review, we detailed mechanistic phenomena which may enhance vasopressor selection, in the course of treating vasodilatory shock.

Therapeutic regimens of endotoxaemia in sheep

Endotoxaemia is an inflammatory condition which happens due to the presence of outer cell wall layer of Gram-negative bacteria in blood circulation, containing lipopolysaccharide commonly known as endotoxin. This condition causes high mortality in affected animals and sheep are highly susceptible in this regard. Several researchers have emphasised the therapeutic regimens of endotoxaemia and its sequels in sheep. Furthermore, sheep are among the most commonly used animal species in experimental studies on endotoxaemia, and for the past five decades, ovine models have been employed to evaluate different aspects of endotoxaemia. Currently, there are several studies on experimentally induced endotoxaemia in sheep, and information regarding novel therapeutic protocols in this species contributes to better understanding and treating the condition. This review aims to specifically introduce various treatment methods of endotoxaemia in sheep.

A Randomized Porcine Study in Low Cardiac Output of Vasoactive and Inotropic Drug Effects on the Gastrointestinal Tract

BACKGROUND

Splanchnic vasodilation by inodilators is an argument for their use in critical cardiac dysfunction. To isolate peripheral vasoactivity from inotropy, such drugs were investigated, and contrasted to vasopressors, in a fixed low cardiac output (CO) model resembling acute cardiac dysfunction effects on the gastrointestinal tract. We hypothesized that inodilators would vasodilate and preserve the aerobic metabolism in the splanchnic circulation in low CO.

METHODS

In anesthetized pigs, CO was lowered to 60% of baseline by partial inferior caval vein balloon inflation. The animals were randomized to placebo (n = 8), levosimendan (24 μg kg-1 bolus, 0.2 μg kg-1 min-1, n = 7), milrinone (50 μg kg-1 bolus, 0.5 μg kg-1 min-1, n = 7), vasopressin (0.001, 0.002 and 0.006 U kg-1 min-1, 1 h each, n = 7) or norepinephrine (0.04, 0.12, and 0.36 μg kg-1 min-1, 1 h each, n = 7). Hemodynamic variables including mesenteric blood flow were collected. Systemic, mixed-venous, mesenteric-venous, and intraperitoneal metabolites were analyzed.

RESULTS

Cardiac output was stable at 60% in all groups, which resulted in systemic hypotension, low superior mesenteric artery blood flow, lactic acidosis, and increased intraperitoneal concentrations of lactate. Levosimendan and milrinone did not change any circulatory variables, but levosimendan increased blood lactate concentrations. Vasopressin and norepinephrine increased systemic and mesenteric vascular resistances at the highest dose. Vasopressin increased mesenteric resistance more than systemic, and the intraperitoneal lactate concentration and lactate/pyruvate ratio.

CONCLUSION

Splanchnic vasodilation by levosimendan and milrinone may be negligible in low CO, thus rejecting the hypothesis. High-dose vasopressors may have side effects in the splanchnic circulation.

Risk factors for acute kidney injury in critically ill patients with torso injury: A retrospective observational single-center study

Acute kidney injury (AKI) is common in trauma patients and associated with poor outcomes. Identifying AKI risk factors in trauma patients is important for risk stratification and provision of optimal intensive care unit (ICU) treatment. This study identified AKI risk factors in patients admitted to critical care after sustaining torso injuries.We performed a retrospective chart review involving 380 patients who sustained torso injuries from January 2016 to December 2019. Patients were included if they were aged >15 years, admitted to an ICU, survived for >48 hours, and had thoracic and/or abdominal injuries and no end-stage renal disease. AKI was defined according to the Kidney Disease Improving Global Outcomes definition and staging system. Clinical and laboratory variables were compared between the AKI and non-AKI groups (n = 72 and 308, respectively). AKI risk factors were assessed using multivariate logistic regression analysis.AKI occurred in 72 (18.9%) patients and was associated with higher mortality than non-AKI patients (26% vs 4%, P < .001). Multivariate logistic regression analysis identified bowel injury, cumulative fluid balance >2.5 L for 24 hours, lactate levels, and vasopressor use (adjusted odds ratio: 2.953, 2.058, 1.170, and 2.910; 95% confidence interval: 1.410-6.181, 1.017-4.164, 1.019-1.343, and 1.414-5.987; P = .004, .045, .026, and .004, respectively) as independent risk factors for AKI.AKI in patients admitted to the ICU with torso injury had a substantial mortality. Recognizing risk factors at an early stage could aid risk stratification and provision of optimal ICU care.

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality.  The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Vasoactive agents in acute mesenteric ischaemia in critical care. A systematic review

Background: Acute mesenteric ischaemia (AMI) is a surgical emergency which has an associated high mortality.  The mainstay of active treatment includes early surgical intervention, with resection of non-viable bowel, and revascularisation of the ischaemic bowel where possible. Due to the physiological insult of AMI however, perioperative care often involves critical care and the use of vasoactive agents to optimise end organ perfusion. A number of these vasoactive agents are currently available with varied mechanism of action and effects on splanchnic blood flow. However, specific guidance on which is the optimal vasoactive drug to use in these settings is limited. This systematic review aimed to evaluate the current evidence comparing vasoactive drugs in AMI. Methods: A systematic search of Ovid Medline, Ovid Embase, Cochrane CENTRAL and the Cochrane Database of Systematic Review was performed on the 5th of November 2020 to identify randomised clinical trials comparing different vasoactive agents in AMI on outcomes including mortality. The search was performed through the Royal College of Surgeons of England (RCSEng) search support library. Results were analysed using the Rayyan platform, and independently screened by four investigators. Results: 614 distinct papers were identified. After screening, there were no randomised clinical trials meeting the inclusion criteria. Conclusions: This review identifies a gap in literature, and therefore recommends an investigation into current practice and clinician preference in relation to vasoactive agents in AMI. Multicentre randomised controlled trials comparing these medications on clinical outcomes will therefore be required to address this question.

Influence of intraoperative vasopressor use on indocyanine green fluorescence angiography: first evaluation in an experimental model

Intraoperative indocyanine green (ICG) fluorescence angiography has gained popularity and acceptance in many surgical fields for the real-time assessment of tissue perfusion. Although vasopressors have the potential to preclude an accurate assessment of tissue perfusion, there is a lack of literature with regards to its effect on ICG fluorescence angiography. An experimental porcine model was used to expose the small bowel for quantitative tissue perfusion assessment. Three increasing doses of norepinephrine infusion (0.1, 0.5, and 1.0 µg/kg/min) were administered intravenously over a 25-min interval. Time-to-peak fluorescence intensity (TTP) was the primary outcome. Secondary outcomes included absolute fluorescence intensity and local capillary lactate (LCL) levels. Five large pigs (mean weight: 40.3 ± 4.24 kg) were included. There was no significant difference in mean TTP (in seconds) at baseline (4.23) as compared to the second (3.90), third (4.41), fourth (4.60), and fifth ICG assessment (5.99). As a result of ICG accumulation, the mean and the maximum absolute fluorescence intensity were significantly different as compared to the baseline assessment. There was no significant difference in LCL levels (in mmol/L) at baseline (0.74) as compared to the second (0.82), third (0.64), fourth (0.60), and fifth assessment (0.62). Increasing doses of norepinephrine infusion have no significant influence on bowel perfusion using ICG fluorescence angiography.

Cardiovascular Responses During Sepsis

Sepsis is the life-threatening organ dysfunction arising from a dysregulated host response to infection. Although the specific mechanisms leading to organ dysfunction are still debated, impaired tissue oxygenation appears to play a major role, and concomitant hemodynamic alterations are invariably present. The hemodynamic phenotype of affected individuals is highly variable for reasons that have been partially elucidated. Indeed, each patient's circulatory condition is shaped by the complex interplay between the medical history, the volemic status, the interval from disease onset, the pathogen, the site of infection, and the attempted resuscitation. Moreover, the same hemodynamic pattern can be generated by different combinations of various pathophysiological processes, so the presence of a given hemodynamic pattern cannot be directly related to a unique cluster of alterations. Research based on endotoxin administration to healthy volunteers and animal models compensate, to an extent, for the scarcity of clinical studies on the evolution of sepsis hemodynamics. Their results, however, cannot be directly extrapolated to the clinical setting, due to fundamental differences between the septic patient, the healthy volunteer, and the experimental model. Numerous microcirculatory derangements might exist in the septic host, even in the presence of a preserved macrocirculation. This dissociation between the macro- and the microcirculation might account for the limited success of therapeutic interventions targeting typical hemodynamic parameters, such as arterial and cardiac filling pressures, and cardiac output. Finally, physiological studies point to an early contribution of cardiac dysfunction to the septic phenotype, however, our defective diagnostic tools preclude its clinical recognition. © 2021 American Physiological Society. Compr Physiol 11:1605-1652, 2021.

Serious Gastrointestinal Complications After Cardiac Surgery and Associated Mortality

BACKGROUND

Severe gastrointestinal (GI) complications (GICs) after cardiac surgery are associated with poor outcomes. Herein, we characterize the severe forms of GICs and associated risk factors of mortality.

METHODS

We retrospectively analyzed the clinically significant postoperative GICs after cardiac surgical procedures performed at our institution from January 2010 to April 2017. Multivariable analysis was used to identify predictors for in-hospital mortality.

RESULTS

Of 29,909 cardiac surgical procedures, GICs occurred in 1037 patients (3.5% incidence), with overall in-hospital mortality of 14% compared with 1.6% in those without GICs. GICs were encountered in older patients with multiple comorbidities who underwent complex prolonged procedures. The most lethal GICs were mesenteric ischemia (n = 104), hepatopancreatobiliary (HPB) dysfunction (n = 139), and GI bleeding (n = 259), with mortality rates of 45%, 27%, and 17%, respectively. In the mesenteric ischemia subset, coronary artery disease (odds ratio [OR], 4.57; P = .002], coronary bypass grafting (OR, 6.50; P = .005), reoperation for bleeding/tamponade (OR, 12.07; P = .01), and vasopressin use (OR, 11.27; P < .001) were predictors of in-hospital mortality. In the HPB complications subset, hepatic complications occurred in 101 patients (73%), pancreatitis in 38 (27%), and biliary disease in 31 (22%). GI bleeding occurred in 20 patients (31%) with HPB dysfunction. In the GI bleeding subset, HPB disease (OR, 10.99; P < .001) and bivalirudin therapy (OR, 12.84; P = .01) were predictors for in-hospital mortality.

CONCLUSIONS

Although relatively uncommon, severe forms of GICs are associated with high mortality. Early recognition and aggressive treatment are mandatory to improve outcomes.

Systematic review and meta-analysis appraising efficacy and safety of adrenaline for adult cardiopulmonary resuscitation

BACKGROUND

There is a beneficial effect of adrenaline during adult cardiopulmonary resuscitation (CPR) from cardiac arrest but there is also uncertainty about its safety and effectiveness. The aim of this study was to evaluate the use of adrenaline versus non-adrenaline CPR.

METHODS

PubMed, ScienceDirect, Embase, CENTRAL (Cochrane Central Register of Controlled Trials) and Google Scholar databases were searched from their inception up to 1st July 2020. Two reviewers independently assessed eligibility and risk of bias, with conflicts resolved by a third reviewer. Risk ratio (RR) or mean difference of groups were calculated using fixed or random-effect models.

RESULTS

Nineteen trials were identified. The use of adrenaline during CPR was associated with a significantly higher percentage of return of spontaneous circulation (ROSC) compared to non-adrenaline treatment (20.9% vs. 5.9%; RR = 1.87; 95% confidence interval [CI] 1.37-2.55; p < 0.001). The use of adrenaline in CPR was associated with ROSC at 19.4% and for non-adrenaline treatment - 4.3% (RR = 3.23; 95% CI 1.89-5.53; p < 0.001). Survival to discharge (or 30-day survival) when using adrenaline was 6.8% compared to non-adrenaline treatment (5.5%; RR = 0.99; 95% CI 0.76-1.30; p = 0.97). However, the use of adrenaline was associated with a worse neurological outcome (1.6% vs. 2.2%; RR = 0.57; 95% CI 0.42-0.78; p < 0.001).

CONCLUSIONS

This review suggests that resuscitation with adrenaline is associated with the ROSC and survival to hospital discharge, but no higher effectiveness was observed at discharge with favorable neurological outcome. The analysis showed higher effectiveness of ROSC and survival to hospital discharge in non-shockable rhythms. But more multicenter randomized controlled trials are needed in the future.

Pathophysiology and protective approaches of gut injury in critical illness

The gut is a complex organ that has played an important role in digestion, absorption, endocrine functions, and immunity. The gut mucosal barriers consist of the immunologic barrier and nonimmunologic barrier. During critical illnesses, the gut is susceptible to injury due to the induction of intestinal hyperpermeability. Gut hyperpermeability and barrier dysfunction may lead to systemic inflammatory response syndrome. Additionally, gut microbiota are altered during critical illnesses. The etiology of such microbiome alterations in critical illnesses is multifactorial. The interaction or systemic host defense modulation between distant organs and the gut microbiome is increasingly studied in disease research. No treatment modality exists to significantly enhance the gut epithelial integrity, permeability, or mucus layer in critically ill patients. However, multiple helpful approaches including clinical and preclinical strategies exist. Enteral nutrition is associated with an increased mucosal barrier in animal and human studies. The trophic effects of enteral nutrition might help to maintain the intestinal physiology, prevent atrophy of gut villi, reduce intestinal permeability, and protect against ischemia-reperfusion injury. The microbiome approach such as the use of probiotics, fecal microbial transplantation, and selective decontamination of the digestive tract has been suggested. However, its evidence does not have a high quality. To promote rapid hypertrophy of the small bowel, various factors have been reported, including the epidermal growth factor, membrane permeant inhibitor of myosin light chain kinase, mucus surrogate, pharmacologic vagus nerve agonist, immune-enhancing diet, and glucagon-like peptide-2 as preclinical strategies. However, the evidence remains unclear.

Effects of Norepinephrine on the Intestinal Vascular System in Rabbits With Endotoxic Shock

ABSTRACT

We hypothesized that jejunal mucosal tissue blood flow would decrease following norepinephrine (NE) administration in endotoxic shock. We aimed of this study to evaluate changes in superior mesenteric venous (SMV) blood flow and jejunal mucosal tissue blood flow of the intestinal vascular system over time by administration of NE in rabbits with endotoxic shock. We created four groups (n = 8 each): control group, lipopolysaccharide (LPS; 1 mg/kg) group, NE (2 μg/kg/min) group, and LPS+NE group. As indicators of circulation, we measured mean arterial blood pressure (MAP), cardiac output, SMV blood flow, and jejunal mucosal tissue blood flow every 30 min from 0 to 240 min. The drop in MAP observed in the LPS group was suppressed by NE administration. SMV blood flow dropped temporarily with LPS administration, but then rose thereafter. Administration of NE to the LPS group suppressed the transient decline in SMV blood flow, which did not drop below that of the control group. In the LPS group, jejunal mucosal tissue blood flow transiently dropped and then rose, reflecting the pattern in SMV blood flow. In the LPS+NE group, however, although there was no drop in SMV blood flow, jejunal mucosal tissue blood flow remained low. An interaction between NE and LPS was observed regarding jejunal mucosal tissue blood flow from 90 to 180 min (P = 0.033). We showed that NE maintained MAP and SMV blood flow but decreased jejunal mucosal tissue blood flow. In a rabbit model of endotoxic shock, NE had a negative effect on jejunal mucosal tissue blood flow.

Safety and Tolerance of Enteral Nutrition in the Medical and Surgical Intensive Care Unit Patient Receiving Vasopressors

BACKGROUND

Multiple societal guidelines recommend enteral nutrition (EN) be initiated within 24 to 48 hours of admission to the intensive care unit (ICU) once a patient is hemodynamically stable. Gastrointestinal intolerance and occurrence of bowel ischemia have been a concern for patients receiving vasopressors while concurrently receiving luminal nutrients. The study objective was to determine whether patients receiving vasopressors while concomitantly receiving enteral nutrients had more incidences of bowel ischemia and intolerance than those receiving EN without vasopressor agents.

METHODS

This retrospective study included 319 medical and surgical ICU patients from a level 1 trauma center. The patients were either receiving vasopressors simultaneously with EN (n = 178) or EN alone (n = 141). Data regarding gastric residual volume (GRV), new abdominal pain, emesis, and bowel ischemia were collected.

RESULTS

There were more patients who had elevated GRV in the group that received vasopressors than patients who did not (20% vs 7%; P-value < .01). There were no differences between rates of bowel ischemia, emesis, or new abdominal pain between the 2 groups.

CONCLUSION

Based on our findings, EN is generally well tolerated and safe for those patients simultaneously receiving vasopressors.

Epinephrine treatment but not time to ROSC is associated with intestinal injury in patients with cardiac arrest

AIM

Current guidelines suggest the use of epinephrine in patients with cardiac arrest (CA). However, evidence for increased survival in good neurological condition is lacking. In experimental settings, epinephrine-induced impairment of microvascular flow was shown. The aim of our study was to analyze the association between epinephrine treatment and intestinal injury in patients after CA.

METHODS

We have included 52 patients with return of spontaneous circulation (ROSC) after CA admitted to our medical intensive care unit (ICU). Blood was taken on admission and levels of circulating intestinal fatty acid binding protein (iFABP) were analyzed.

RESULTS

Patients were 64 (49.8-73.8) years old and predominantly male (76.9%). After six months, 50% of patients died and 38.5% of patients had a cerebral performance category (CPC)-score of 1-2. iFABP levels were lower in survivors (234 IQR 90-399 pg/mL) as compared to non-survivors (283, IQR 86-11500 pg/mL; p < 0.05). Plasma levels of iFABP were not associated with time to ROSC but correlated with epinephrine-dose (R = 0.32; p < 0.05). 40% of patients receiving ≥3 mg of epinephrine as compared to 10.5% of patients treated with <3 mg (p < 0.05) developed iFABP plasma levels >1500 pg/mL, which was associated with dramatically increased mortality (HR4.87, 95%CI 1.95-12.1; p < 0.001). iFABP levels predicted mortality independent from time to ROSC and the disease severity score SAPS II. In contrast to mortality, iFABP plasma levels were not associated with neurological outcome.

CONCLUSIONS

In this small, single centre study, cumulative dose of epinephrine used in cardiac arrest patients was associated with an increase in biomarker indicative of intestinal injury and 6-month mortality.

Population Pharmacokinetic Model of Dexmedetomidine in a Heterogeneous Group of Patients

Dexmedetomidine is a hepatically eliminated drug with sedative, anxiolytic, sympatholytic, and analgesic properties that has been increasingly used for various indications in the form of a short or continuous intravenous infusion. This study aimed to propose a population pharmacokinetic (PK) model of dexmedetomidine in a heterogeneous group of intensive care unit patients, incorporating 29 covariates potentially linked with dexmedetomidine PK. Data were collected from 70 patients aged between 0.25 and 88 years and treated with dexmedetomidine infusion for various durations at 1 of 4 medical centers. Statistical analysis was performed using a nonlinear mixed-effect model. Categorical and continuous covariates including demographic data, hemodynamic parameters, biochemical markers, and 11 single-nucleotide polymorphisms were tested. A 2-compartment model was used to describe dexmedetomidine PK. An allometric/isometric scaling was used to account for body weight difference in PK parameters, and the Hill equation was used to describe the maturation of clearance. Typical values of the central and peripheral volume of distribution and the systemic and distribution clearance for a theoretical adult patient were central volume of distribution = 22.50 L, peripheral volume of distribution  = 86.1 L, systemic clearance =  34.7 L/h, and distribution clearance = 40.8 L/h. The CYP1A2 genetic polymorphism and noradrenaline administration were identified as significant covariates for clearance. A population PK model of dexmedetomidine was successfully developed. The proposed model is well calibrated to the observed data. The identified covariates account for <5% of interindividual variability and consequently are of low clinical significance for the purpose of dose adjustment.

Risk Factors for Acute Mesenteric Ischemia in Critically Ill Burns Patients-A Matched Case-Control Study

OBJECTIVE

Burn-induced shock can lead to tissue hypoperfusion, including the gut. We performed this study to describe burn patients at risk of acute mesenteric ischemia (AMI) with the aim to identify potential modifiable risk factors.

METHODS

Retrospective case-control study including adult severely burned patients between August 2012 and March 2017. Patients who developed AMI were matched to severely burned patients without AMI at a ratio of 1:3 (same year of admission, Abbreviated Burn Severity Index [ABSI], and Simplified Acute Physiology Score II [SAPSII]). Univariate and multiple regression analyses were performed.

RESULTS

Of 282 severely burned patients, 15 (5%) were diagnosed with AMI. In the AMI group, patients had a median (interquartile range) total body surface area (TBSA), SAPSII, and ABSI of 55 (25-63)%, 53 (39-70), and 11 (8-13), respectively. The AMI mechanism in all patients was nonocclusive. Decreased cardiac index within the first 24 h (H24 CI), higher sequential organ failure assessment score on day 1 (D1 SOFA), and hydroxocobalamin use were associated with AMI. Odds ratios were 0.18 (95% confidence interval [CI], 0.03-0.94), 1.6 (95% CI, 1.2-2.1), and 4.6 (95% CI, 1.3-15.9), respectively, after matching. Multiple regression analysis showed that only decreased H24 CI and higher D1 SOFA were independently associated with AMI. Ninety-day mortality was higher in the AMI group (93% vs. 46% [P = 0.001]).

CONCLUSIONS

Burns patients with initial low cardiac output and early multiple organ dysfunction are at high risk of nonocclusive AMI.

Vasopressors and Nutrition Therapy: Safe Dose for the Outset of Enteral Nutrition?

Background and Aims

Patients with hemodynamic instability need to receive intensive treatment as fluid replacement and vasoactive drugs. In the meantime, it is supposed to initiate nutritional therapy within 24 to 48 hours after admission to the intensive care unit (ICU), as an essential part of patient's intensive care and better outcomes. However, there are many controversies tangential to the prescription of enteral nutrition (EN) concomitant to the use of vasopressor and its doses. In this way, the present study aimed to identify what the literature presents of evidence to guide the clinical practice concerning the safe dose of vasopressors for the initiation of nutritional therapy in critically ill patients.

Methods

This review was carried out in PubMed, ProQuest, Web of Science, and Medline databases. The descriptors were used to perform the search strategy: Critical Care, Intensive Care Units, Vasoconstrictor Agents, and Enteral Nutrition. Inclusion criteria were patients of both genders, over 18 years of age, using vasoactive drugs, with the possibility of receiving EN therapy, and articles written in English, Portuguese, and Spanish. In addition, exclusion criteria were case reports, non-papers, and repeated papers.

Results

10 articles met our inclusion criteria.

Conclusion

It was observed that there are many controversies about the supply of EN in critically ill patients using vasopressor, especially about the safe dose, and it was not possible to identify a cutoff value for the beginning therapy. Despite the drug doses, clinical signs are still the most important parameters in the evaluation of EN tolerance.

Secondary Sclerosing Cholangitis in Critically Ill Patients: An Underdiagnosed Entity

Secondary sclerosing cholangitis in critically ill patients (SSC-CIP) is a recently identified cholestatic liver disease occurring in patients without prior history of hepatobiliary disease, after receiving treatment in the intensive care unit (ICU) in different settings, including cardiothoracic surgery, infection, trauma, and burns. It is a rare entity, being estimated to occur in 1/2,000 patients in an ICU; however, it is a dismal condition, with up to half of the patients dying during the ICU stay and with rapid progression to liver cirrhosis over weeks to months. SSC-CIP should be considered in the differential diagnosis of cholestasis in the ICU, particularly when cholestasis persists after recovery from the critical event. Diagnosis is established with magnetic resonance cholangiopancreatography or endoscopic retrograde cholangiopancreatography showing dilations and stenoses of the intrahepatic bile ducts as well as biliary casts. No available treatment has been shown to slow the rapid progression of the disease, and liver transplant referral should be considered early after the diagnosis of SSC-CIP. Increased awareness and timely diagnosis are crucial in order to improve the current appalling outcome.

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.

Norepinephrine-associated left ventricular outflow tract obstruction and systolic anterior movement

In the perioperative setting, norepinephrine is used to increase blood pressure, an effect mediated mostly via arterial and venous vasoconstriction. Thus, norepinephrine is, allegedly, less likely to cause or worsen left ventricular outflow tract obstruction (LVOTO) than other inotropes. We report a case of norepinephrine-associated dynamic LVOTO and systolic anterior movement in a predisposed patient. This report highlights that unrecognised dynamic LVOTO may worsen shock parameters in patients treated with norepinephrine who have underlying myocardial hypertrophy.

Evaluation and Management of Abdominal Compartment Syndrome in the Emergency Department

BACKGROUND

Abdominal compartment syndrome is a potentially deadly condition that can be missed in the emergency department setting.

OBJECTIVE

The purpose of this narrative review article is to provide a summary of the background, pathophysiology, diagnosis, and management of abdominal compartment syndrome with a focus on emergency clinicians.

DISCUSSION

Abdominal compartment syndrome is caused by excessive pressure within the abdominal compartment due to diminished abdominal wall compliance, increased intraluminal contents, increased abdominal contents, or capillary leak/fluid resuscitation. History and physical examination are insufficient in isolation, and the gold standard is intra-abdominal pressure measurement. Abdominal compartment syndrome is defined as an intra-abdominal pressure >20 mm Hg with evidence of end-organ injury. Management involves increasing abdominal wall compliance (e.g., analgesia, sedation, and neuromuscular blocking agents), evacuating gastrointestinal contents (e.g., nasogastric tubes, rectal tubes, and prokinetic agents), avoiding excessive fluid resuscitation, draining intraperitoneal contents (e.g., percutaneous drain), and decompressive laparotomy in select cases. Patients are critically ill and often require admission to a critical care unit.

CONCLUSIONS

Abdominal compartment syndrome is an increasingly recognized condition with the potential for significant morbidity and mortality. It is important for clinicians to be aware of the current evidence regarding the diagnosis, management, and disposition of these patients.

Microcirculation in Cardiovascular Diseases

Microcirculation is a system composed of interconnected microvessels, which is responsible for the distribution of oxygenated blood among and within organs according to regional metabolic demand. Critical medical conditions, e. g., sepsis, and heart failure are known triggers of microcirculatory disturbance, which usually develops early in such clinical pictures and represents an independent risk factor for mortality. Therefore, hemodynamic resuscitation aiming at restoring microcirculatory perfusion is of paramount importance. Until recently, however, resuscitation protocols were based on macrohemodynamic variables, which increases the risk of under or over resuscitation. The introduction of hand-held video-microscopy (HVM) into clinical practice has allowed real-time analysis of microcirculatory variables at the bedside and, hence, favored a more individualized approach. In the cardiac intensive care unit scenario, HVM provides essential information on patients' hemodynamic status, e. g., to classify the type of shock, to adequate the dosage of vasopressors or inotropes according to demand and define safer limits, to guide fluid therapy and red blood cell transfusion, to evaluate response to treatment, among others. Nevertheless, several drawbacks have to be addressed before HVM becomes a standard of care.

Gut rest strategy and trophic feeding in the acute phase of critical illness with acute gastrointestinal injury

Critically ill patients frequently suffer from gastrointestinal dysfunction as the intestine is a vulnerable organ. In critically ill patients who require nutritional support, the current guidelines recommend the use of enteral nutrition within 24-48 h and advancing towards optimal nutritional goals over the next 48-72 h; however, this may be contraindicated in patients with acute gastrointestinal injury because overuse of the gut in the acute phase of critical illness may have an adverse effect on the prognosis. We propose that trophic feeding after 72 h, as a partial gut rest strategy, should be provided to critically ill patients during the acute phase of illness as an organ-protective strategy, especially for those with acute gastrointestinal injury.

Vasoactive Agent Use in Septic Shock: Beyond First-Line Recommendations

Septic shock is a life-threatening disorder associated with high mortality rates requiring rapid identification and intervention. Vasoactive agents are often required to maintain goal hemodynamics and preserve tissue perfusion. However, guidance regarding the proper administration of adjunct agents for the management of septic shock is limited in patients who are refractory to norepinephrine. This review summarizes vasopressor agents and describes the nuanced application of these agents in patients with septic shock, specifically focusing on clinical scenarios with limited guidance including patients who are nonresponsive to first-line agents and individuals with mixed shock states, tachyarrhythmias, obesity, valvular abnormalities, or other comorbid conditions.

Norepinephrine Contributes to Enterocyte Damage in Septic Shock Patients: A Prospective Cohort Study

OBJECTIVES

In septic patients, both systemic inflammation and splanchnic hypoperfusion may cause enterocyte damage. Catecholamines may exert additional detrimental effects on mesenteric blood flow in these patients, and thereby contribute to this damage. Enterocyte damage itself results in impairment of gut barrier function and consequent translocation of bacteria/toxins. This may contribute to multiple organ failure and death by sustaining or amplifying the systemic inflammatory response. The aim of the study was 2-fold: to investigate which factors contribute to enterocyte damage in septic patients, and to assess whether enterocyte damage is associated with a sustained or amplified systemic inflammatory response.

METHODS

In this prospective observational cohort study in 129 patients with septic shock admitted to the ICU, we serially measured plasma levels of Intestinal Fatty Acid-Binding Protein (I-FABP, a marker for enterocyte damage) and of cytokines Tumor Necrosis Factor (TNF)-α, Interferon (IFN)-y, Interleukin (IL)-1β, IL-6, IL-8, IL-1 Receptor Antagonist (RA), and IL-10. Clinical data were collected from electronic patient files.

RESULTS

A total of 129 patients were included in the study. The median age of the patients was 67 years [56-74]. The median norepinephrine infusion rate was 0.2 μg/kg/min [0.1-0.5]. Overall, 28-day mortality was 31 (24%). Similar to previous work, I-FABP levels at admission were independently associated with mortality (odds ratio 3.101 [1.138-8.448]). Acute Physiology and Chronic Health Evaluation II score and an increase in norepinephrine infusion rate between days 1 and 3 were independently associated with area under curve I-FABP levels, whereas mean arterial pressure and creatinine levels were not. No correlations were found between any of the measured cytokines and plasma I-FABP levels. Furthermore, high I-FABP levels were not related with the subsequent course of cytokine levels.

CONCLUSIONS

In patients with septic shock, norepinephrine use is associated with more enterocyte damage. Although enterocyte damage is associated with increased 28-day mortality, it is not associated with a sustained or amplified systemic inflammatory response.

Changes in the sublingual microcirculation following aortic surgery under balanced or total intravenous anaesthesia: a prospective observational study

Background

In vascular surgery with aortic cross-clamping, ischemia/reperfusion injury induces systemic haemodynamic and microcirculatory disturbances. Different anaesthetic regimens may have a varying impact on tissue perfusion. The aim of this study was to explore changes in microvascular perfusion in patients undergoing elective open abdominal aortic aneurysm repair under balanced or total intravenous anaesthesia.

Methods

Prospective observational study. Patients undergoing elective open infrarenal abdominal aortic aneurysm repair received balanced (desflurane + remifentanil, n = 20) or total intravenous anaesthesia (TIVA, propofol + remifentanil using target-controlled infusion, n = 20) according to the clinician’s decision. A goal-directed haemodynamic management was applied in all patients. Measurements were obtained before anaesthesia induction (baseline) and at end-surgery and included haemodynamics, arterial/venous blood gases, sublingual microvascular flow and density (incident dark field illumination imaging), peripheral muscle tissue oxygenation and microcirculatory reactivity (thenar near infrared spectroscopy with a vascular occlusion test).

Results

The two groups did not differ for baseline characteristics, mean aortic-clamping time and requirement of vasoactive agents during surgery. Changes in mean arterial pressure, systemic vascular resistance index, haemoglobin and blood lactate levels were similar between the two groups, while the cardiac index increased at end-surgery in patients undergoing balanced anaesthesia. The sublingual microcirculation was globally unaltered in the TIVA group at end-surgery, while patients undergoing balanced anaesthesia showed an increase in the total and perfused small vessel densities (from 16.6 ± 4.2 to 19.1 ± 5.4 mm/mm², p < 0.05). Changes in microvascular density were negatively correlated with changes in the systemic vascular resistance index. The area of reactive hyperaemia during the VOT increased in the balanced anaesthesia group (from 14.8 ± 8.1 to 25.6 ± 14.8%*min, p < 0.05). At end-surgery, the tissue haemoglobin index in the TIVA group was lower than that in the balanced anaesthesia group.

Conclusions

In patients undergoing elective open abdominal aortic aneurysm repair with a goal-directed hemodynamic management, indices of sublingual or peripheral microvascular perfusion/oxygenation were globally preserved with both balanced anaesthesia and TIVA. Patients undergoing balanced anaesthesia showed microvascular recruitment at end-surgery.

Trial registration

NCT03510793, https://www.clinicaltrials.gov, date of registration April 27th 2018, retrospectively registered.

Sepsis-induced acute kidney injury: A disease of the microcirculation

AKI is a common complication of sepsis and is significantly associated with mortality. Sepsis accounts for more than 50% of the cases of AKI, with a mortality rate of up to 40%. The pathogenesis of septic AKI is complex, but there is emerging evidence that, at least in the first 48 hours, the defects may be functional rather than structural in nature. For example, septic AKI is associated with an absence of histopathological changes, but with microvascular abnormalities and tubular stress. In this context, renal medullary hypoxia due to redistribution of intra-renal perfusion is emerging as a critical mediator of septic AKI. Clinically, vasopressor drugs remain the cornerstone of therapy for maintenance of blood pressure and organ perfusion. However, in septic AKI, there is insensitivity to vasopressors such as norepinephrine, leading to persistent hypotension and organ failure. Vasopressin, angiotensin II, and, paradoxically, α₂ -adrenergic receptor agonists (clonidine and dexmedetomidine) may be feasible adjunct therapies for catecholamine-resistant vasodilatory shock. In this review, we outline the recent progress made in understanding how these drugs may influence the renal microcirculation, which represents a crucial step toward developing better approaches for the circulatory management of patients with septic AKI.