Decreases in cerebral saturation in patients with septic shock are associated with increased risk of death: a prospective observational single center study

In-Hospital Neurologic Complications, Neuromonitoring, and Long-Term Neurologic Outcomes in Patients With Sepsis: A Systematic Review and Meta-Analysis

OBJECTIVES

Although delirium is well described in patients with sepsis, there are limited data on other neurologic complications. We aimed to systematically review the prevalence, neuromonitoring tools, and neurocognitive outcomes in sepsis patients with neurologic complications.

DATA SOURCES

MEDLINE and six other databases (Embase, Web of Science, Cochrane CENTRAL, and ClinicalTrials.gov ) were searched through January 2023.

STUDY SELECTION

Studies of adult patients with sepsis reported neurologic complications, use of neuromonitoring tools, neuropathology, and cognitive outcomes.

DATA EXTRACTION

Two independent reviewers extracted the data. Random-effect meta-analyses were used to pool data.

DATA SYNTHESIS

Seventy-four studies ( n = 146,855) were included. Neurologic complications were reported in 38 studies ( n = 142,193) including septic encephalopathy (36%, 95% CI, 27-46%; I 2 = 99%), ischemic stroke (5%, 95% CI, 2.1-11.5; I 2 = 99%), intracranial hemorrhage (2%, 95% CI, 1.0-4.4%; I 2 = 96%), seizures (1%, 95% CI, 0.2-7%; I 2 = 96%), posterior reversible encephalopathy syndrome (9%), and hypoxic-ischemic brain injury (7%). In the meta-regression analysis, pulmonary infection, sepsis induced by a gram-positive organism, higher sequential organ failure assessment score, acute physiology and chronic health evaluation II score at admission, and longer ICU length of stay were associated with higher risk of developing septic encephalopathy. Three studies ( n = 159) reported postmortem neuropathological findings, acute brain injury was noted in 47% of patients. Twenty-six studies ( n = 1,358) reported the use of neuromonitoring tools, electroencephalogram was the most used tool for seizure detection. Transcranial Doppler and near infrared spectroscopy were used for monitoring cerebral hemodynamic changes to detect early ischemia. Six studies reported cognitive outcomes ( n = 415) up to 12 months postdischarge and cognitive impairment (≥ one domain) was reported in 30%.

CONCLUSIONS

In-hospital neurologic complications are common in patients with sepsis. However, the mechanism and timing of those sepsis-associated complications are poorly understood and there are limited data on standardized neuromonitoring in this population.

The Incidence and Magnitude of Cerebral Desaturation in Traumatic Brain Injury: An Observational Cohort Study

BACKGROUND

Cerebral ischemia in patients with traumatic brain injury (TBI) may propagate secondary neurological injury. Episodes of cerebral ischemia can be revealed through the use of cerebral oximetry monitoring. The objective of this study was to determine the incidence and severity of regional cerebral oxygen (rSO2) desaturation (rSO2<65%) in patients with severe TBI. Secondary outcomes included changes in other monitoring parameters associated with cerebral desaturation.

MATERIALS AND METHODS

In this single-center prospective observational cohort study, cerebral oximetry data were collected continuously for up to 72 hours in 18 adult patients with a diagnosis of severe nonpenetrating TBI who were being mechanically ventilated and undergoing intracranial pressure (ICP) monitoring an in intensive care unit in Canada. Mean arterial pressure (MAP), ICP, and cerebral perfusion pressure were collected at 5-minute intervals during the study period.

RESULTS

Twelve of 18 (67%) patients experienced an episode of cerebral desaturation. The median (interquartile range) nadir rSO2 was 57% (51% to 62%). The duration of desaturation was 265 (57 to 1277) minutes or 8.1% (2.6% to 26.0%) of recording time. In all patients, a linear regression analysis of the area under threshold of 65% for rSO2 was moderately correlated with the area above an ICP threshold of 20 mm Hg (R2=0.52; P<0.01). Similarly, there was a modest correlation between rSO2 and MAP (R2=0.41; P<0.01). These relationships also held true for those patients who experienced cerebral desaturation. Patients having episodes of ICP >20 mm Hg were 6 times more likely to have a cerebral desaturation (relative risk: 6.0; 95% confidence interval: 1.3-34.7).

CONCLUSIONS

Cerebral desaturations occur frequently in patients with severe TBI, and their duration can be protracted. Episodes of desaturation were moderately correlated with increased ICP and decreased MAP.

The role of non-invasive brain oximetry in adult critically ill patients without primary brain injury

A primary objective in intensive care and perioperative settings is to promote an adequate supply and delivery of oxygen to tissues and organs, particularly to the brain. Cerebral near infrared spectroscopy (NIRS) is a non-invasive, continuous monitoring technique, that can be used to assess cerebral oxygenation. Using NIRS to monitor cerebral oximetry is not new, and has been in widespread use in neonates and cardiac surgery for decades. In addition, it has become common to see NIRS being used in adult and pediatric cardiac surgery, acute neurological diseases, neurosurgical procedures, vascular surgery, severe trauma and other acute medical diseases. Furthermore, recent evidence suggests a role for NIRS in the perioperative settings; detecting and preventing episodes of cerebral desaturation aiming to reduce the development of post-operative delirium. NIRS is not without its limitations; these include the risk of extra-cranial contamination, spatial limitations and skin blood flow/volume changes, as well being a measure of localized blood oxygenation underneath the sensor. However, NIRS is a non-invasive technique and can, therefore, be used in those patients without indications or justification for invasive brain monitoring; non-neurosurgical procedures such as liver transplantation, major orthopedic surgery and critically illness where the brain is at risk. The aim of this manuscript was to discuss the physical principles of NIRS and to report the current evidence regarding its use in critically ill patients without primary non-anoxic brain injury.

The Use of Near-Infrared Spectroscopy and/or Transcranial Doppler as Non-Invasive Markers of Cerebral Perfusion in Adult Sepsis Patients With Delirium: A Systematic Review

Background:

Several studies have previously reported the presence of altered cerebral perfusion during sepsis. However, the role of non-invasive neuromonitoring, and the impact of altered cerebral perfusion, in sepsis patients with delirium remains unclear.

Methods:

We performed a systematic review of studies that used near-infrared spectroscopy (NIRS) and/or transcranial Doppler (TCD) to assess adults (≥18 years) with sepsis and delirium. From study inception to July 28, 2020, we searched the following databases: Ovid MedLine, Embase, Cochrane Library, and Web of Science.

Results:

Of 1546 articles identified, 10 met our inclusion criteria. Although NIRS-derived regional cerebral oxygenation was consistently lower, this difference was only statistically significant in one study. TCD-derived cerebral blood flow velocity was inconsistent across studies. Importantly, both impaired cerebral autoregulation during sepsis and increased cerebrovascular resistance were associated with delirium during sepsis. However, the heterogeneity in NIRS and TCD devices, duration of recording (from 10 seconds to 72 hours), and delirium assessment methods (e.g., electronic medical records, confusion assessment method for the intensive care unit), precluded meta-analysis.

Conclusion:

The available literature demonstrates that cerebral perfusion disturbances may be associated with delirium in sepsis. However, future investigations will require consistent definitions of delirium, delirium assessment training, harmonized NIRS and TCD assessments (e.g., consistent measurement site and length of recording), as well as the quantification of secondary and tertiary variables (i.e., Cox, Mxa, MAP_OPT), in order to fully assess the relationship between cerebral perfusion and delirium in patients with sepsis.

Pathomechanisms of Non-Traumatic Acute Brain Injury in Critically Ill Patients

Delirium, an acute alteration in mental status characterized by confusion, inattention and a fluctuating level of arousal, is a common problem in critically ill patients. Delirium prolongs hospital stay and is associated with higher mortality. The pathophysiology of delirium has not been fully elucidated. Neuroinflammation and neurotransmitter imbalance seem to be the most important factors for delirium development. In this review, we present the most important pathomechanisms of delirium in critically ill patients, such as neuroinflammation, neurotransmitter imbalance, hypoxia and hyperoxia, tryptophan pathway disorders, and gut microbiota imbalance. A thorough understanding of delirium pathomechanisms is essential for effective prevention and treatment of this underestimated pathology in critically ill patients.

Prognostic Value of Tissue Oxygen Monitoring and Regional Cerebral Oxygen Saturation Monitoring and Their Correlation in Neurological Patients with Sepsis: A Preliminary, Prospective, Observational Study

BACKGROUND

There is paucity of literature on the prognostic value of tissue oxygen saturation (StO2) and regional cerebral oxygen saturation (rSO2) in neurological patients with sepsis. In this preliminary study, we investigated the prognostic value of StO2 and rSO2 in a group of neurological patients and correlated StO2 and rSO2 with hemodynamic and metabolic parameters.

MATERIALS AND METHODS

This preliminary, prospective observational study was conducted in 45 adult neurological patients admitted to intensive care unit. Once a diagnosis of sepsis or septic shock was established, parameters of oxygenation (StO2, rSO2, central venous oxygen saturation [ScvO2]), serum lactate, illness severity scores (Acute Physiology and Chronic Health Evaluation score, Sequential Organ Failure Assessment score, Glasgow Coma Scale) were recorded at 0, 6, 12, 24, 36, and 48 hours, and once daily thereafter. Outcomes were in-hospital mortality attributable to sepsis and the Glasgow outcome score at hospital discharge.

RESULTS

There was a moderately positive correlation between StO2 and rSO2 at baseline (r=0.599; P=0.001). StO2, illness severity scores and serum lactate, but not rSO2, were significantly different between survivors (n=29) and nonsurvivors (n=16) at baseline and during the first 48 hours. An rSO2 of 62.5% had a sensitivity of 83% and specificity of 67% to differentiate survivors and nonsurvivors of septic shock at 48 hours. StO2 had a higher correlation with ScvO2 and serum lactate than rSO2.

CONCLUSIONS

StO2 prognosticates survival and favorable/unfavorable outcomes in neurological patients with sepsis. The role of rSO2 in predicting survival in milder form of sepsis is doubtful.

A neonatal sequential organ failure assessment score predicts mortality to late-onset sepsis in preterm very low birth weight infants

BACKGROUND

An operational definition of organ dysfunction applicable to neonates that predicts mortality in the setting of infection is lacking. We determined the utility of an objective, electronic health record (EHR)-automated, neonatal sequential organ failure assessment (nSOFA) score to predict mortality from late-onset sepsis (LOS) in premature, very low birth weight (VLBW) infants.

METHODS

Retrospective, single-center study of bacteremic preterm VLBW newborns admitted between 2012 and 2016. nSOFA scores were derived for patients with LOS at multiple time points surrounding the sepsis evaluation.

RESULTS

nSOFA scores at evaluation and at all points measured after evaluation were different between survivors and non-survivors. Among patients with an nSOFA score of >4, mortality was higher at evaluation (13% vs 67%, p < 0.001), +6 h (15% vs 64%, p = 0.002), and +12 h (7% vs 71%, p < 0.001) as compared to patients with a score of ≤4. Receiver operating characteristics area under the curve was 0.77 at evaluation (95% CI 0.62-0.92; p = 0.001), 0.78 at +6 h (0.66-0.92; p < 0.001), and 0.93 at +12 h (0.86-0.997; p < 0.001).

CONCLUSIONS

The nSOFA scoring system predicted mortality in VLBW infants with LOS and this automated system was integrated into our EHR. Prediction of LOS mortality is a critical step toward improvements in neonatal sepsis outcomes.

Vasopressor Therapy and the Brain: Dark Side of the Moon

Sepsis, a leading cause of morbidity and mortality, is caused by a deregulated host response to pathogens, and subsequent life-threatening organ dysfunctions. All major systems, including the cardiovascular, respiratory, renal, hepatic, hematological, and the neurological system may be affected by sepsis. Sepsis associated neurological dysfunction is triggered by multiple factors including neuro-inflammation, excitotoxicity, and ischemia. Ischemia results from reduced cerebral blood flow, caused by extreme variations of blood pressure, occlusion of cerebral vessels, or more subtle defects of the microcirculation. International guidelines comprehensively describe the initial hemodynamic management of sepsis, revolving around the normalization of systemic hemodynamics and of arterial lactate. By contrast, the management of sepsis patients suffering from brain dysfunction is poorly detailed, the only salient point being mentioned is that sedation and analgesia should be optimized. However, sepsis and the hemodynamic consequences thereof as well as vasopressors may have severe untoward neurological consequences. The current review describes the general neurological complications, as well as the consequences of vasopressor therapy on the brain and its circulation and addresses methods for cerebral monitoring during sepsis.

Use of cerebral oxygen saturation and hemoglobin concentration to predict acute kidney injury after cardiac surgery

Objective

Acute kidney injury (AKI) is a common complication after cardiac surgery and is associated with significant morbidity and mortality. Near infrared spectroscopy (NIRS) is a noninvasive technique for real-time measurement of cerebral tissue oxygenation. The purpose of the present study was to evaluate the correlation of AKI with hemoglobin and regional cerebral oxygen saturation (rScO₂) measured intraoperatively and postoperatively in patients undergoing cardiac surgery.

Methods

We retrospectively analyzed the prospectively collected data of 45 adult patients with normal renal function who underwent isolated coronary artery bypass grafting (CABG) from January 2014 to May 2014. Kidney injury was assessed according to the Acute Kidney Injury Network criteria. rScO₂ and hemoglobin were measured every hour intraoperatively and for the first 24 hours postoperatively.

Results

The hemoglobin concentration and rScO₂ were significantly lower in patients with than without AKI, and no linear trends were observed. No exact cut-off values were obtained.

Conclusion

This retrospective study shows that a lower rScO₂ and hemoglobin concentration are correlated with AKI after CABG in patients with no peripheral vascular disease or recent myocardial infarction. We suggest that cerebral oximetry alone may predict postoperative AKI well.