Transcranial doppler assessment of cerebral perfusion in critically ill septic patients: a pilot study

Alterations in Regional Brain Microcirculation in Patients with Sepsis: A Prospective Study Using Contrast-Enhanced Brain Ultrasound

BACKGROUND

Alterations in regional brain microcirculation have not been well studied in patients with sepsis. Regional brain microcirculation can be studied using contrast-enhanced brain ultrasound (CEUS) with microbubble administration.

METHODS

CEUS was used to assess alterations in regional brain microcirculation on 3 consecutive days in 58 patients with sepsis and within 24 h of intensive care unit admission in 10 aged-matched nonseptic postoperative patients. Time-intensity perfusion curve variables (time-to-peak and peak intensity) were measured in different regions of interest of the brain parenchyma. The mean arterial pressure, cardiac index (using transthoracic echocardiography), global cerebral blood flow (using echo-color Doppler of the carotid and vertebral arteries), mean flow velocities of the middle cerebral arteries, and brain autoregulation (using transcranial echo-color Doppler) were measured simultaneously. The presence of structural brain injury in patients with sepsis was confirmed on computed tomography imaging, and encephalopathy, including coma and delirium, was evaluated using the Glasgow Coma Scale and the Confusion Assessment Method in the Intensive Care Unit.

RESULTS

Of the 58 patients with sepsis, 42 (72%) developed acute encephalopathy and 11 (19%) had some form of structural brain injury. Brain autoregulation was impaired in 23 (40%) of the patients with sepsis. Brain microcirculation alterations were observed in the left lentiform nucleus and left white matter of the temporoparietal region of the middle cerebral artery in the sepsis nonsurvivors but not in the survivors or postoperative patients. The alterations were characterized by prolonged time-to-peak (p < 0.01) and decreased peak intensity (p < 0.01) on the time-intensity perfusion curve. Prolonged time-to-peak but not decreased peak intensity was independently associated with worse outcome (p = 0.03) but not with the development of encephalopathy (p = 0.77).

CONCLUSIONS

Alterations in regional brain microcirculation are present in critically ill patients with sepsis and are associated with poor outcome. Trial registration Registered retrospectively on December 19, 2019.

Optimizing the prediction of sepsis-associated encephalopathy with cerebral circulation time utilizing a nomogram: a pilot study in the intensive care unit

Background

Sepsis-associated encephalopathy (SAE) is prevalent in intensive care unit (ICU) environments but lacks established treatment protocols, necessitating prompt diagnostic methods for early intervention. Traditional symptom-based diagnostics are non-specific and confounded by sedatives, while emerging biomarkers like neuron-specific enolase (NSE) and S100 calcium-binding protein B (S100B) have limited specificity. Transcranial Doppler (TCD) indicators, although is particularly relevant for SAE, requires high operator expertise, limiting its clinical utility.

Objective

This pilot study aims to utilize cerebral circulation time (CCT) assessed via contrast-enhanced ultrasound (CEUS) as an innovative approach to investigate the accuracy of SAE prediction. Further, these CCT measurements are integrated into a nomogram to optimize the predictive performance.

Methods

This study employed a prospective, observational design, enrolling 67 ICU patients diagnosed with sepsis within the initial 24 h. Receiver operating characteristic (ROC) curve analyses were conducted to assess the predictive accuracy of potential markers including NSE, S100B, TCD parameters, and CCT for SAE. A nomogram was constructed via multivariate Logistic Regression to further explore the combined predictive potential of these variables. The model's predictive performance was evaluated through discrimination, calibration, and decision curve analysis (DCA).

Results

SAE manifested at a median of 2 days post-admission in 32 of 67 patients (47.8%), with the remaining 35 sepsis patients constituting the non-SAE group. ROC curves revealed substantial predictive utility for CCT, pulsatility index (PI), and S100B, with CCT emerging as the most efficacious predictor, evidenced by an area under the curve (AUC) of 0.846. Multivariate Logistic Regression identified these markers as independent predictors for SAE, leading to the construction of a nomogram with excellent discrimination, substantiated by an AUC of 0.924 through bootstrap resampling. The model exhibited satisfactory concordance between observed and predicted probabilities, and DCA confirmed its clinical utility for the prompt identification of SAE.

Conclusion

This study highlighted the enhanced predictive value of CCT in SAE detection within ICU settings. A novel nomogram incorporating CCT, PI, and S100B demonstrated robust discrimination, calibration, and clinical utility, solidifying it as a valuable tool for early SAE intervention.

Relationship Between Cerebral Hemodynamics, Tissue Oxygen Saturation, and Delirium in Patients With Septic Shock: A Pilot Observational Cohort Study

Background: Septic shock patients have tendencies toward impairment in cerebral autoregulation and imbalanced cerebral oxygen metabolism. Tissue Oxygen Saturation (StO₂) and Transcranial Doppler (TCD) monitoring were undertaken to observe the variations of cerebral hemodynamic indices and cerebral/peripheral StO₂ to find risk factors that increase the sepsis-associated delirium (SAD). Materials and Methods: The research cohort was chosen from septic shock patients received in the Department of Critical Care Medicine, Xiangya Hospital, Central South University between May 2018 and March 2019. These patients were separated into two groups, SAD and non-SAD as assessed by using the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Comparisons were made between the two groups in terms of peripheral StO₂, fluctuations in regional cerebral oxygen saturation (rSO₂), cerebral vascular automatic regulation function [Transient Hyperemic Response Ratio (THRR) index], cerebral hemodynamic index, organ function indicators, blood gas analysis indices, and patient characteristics. Results: About 39% of the patients (20/51) suffered from SAD. Nearly 43% of the patients died within 28 days of admission (22/51). Individuals in the SAD cohort needed a longer period of mechanical ventilation [5 (95% CI 2, 6) vs. 1 days (95% CI 1, 4), p = 0.015] and more time in ICU [9 (95% CI 5, 20) vs. 5 days (95% CI 3, 9), p = 0.042]; they also experienced more deaths over the 28-day period (65 vs. 29%, p = 0.011). The multivariate regression analysis indicated that independent variables associated with SAD were THRR index [odds ratio (OR) = 5.770, 95% CI: 1.222-27.255; p = 0.027] and the mean value for rSO₂ was < 55% (OR = 3.864, 95% CI: 1.026-14.550; p = 0.046). Conclusion: Independent risk factors for SAD were mean cerebral oxygen saturation below 55% and cerebrovascular dysregulation (THRR < 1.09).

Dose Escalation and Safety of Capsaicin for Cerebral Perfusion Augmentation: A Pilot Study

[Figure: see text].

Transcranial Doppler Can Predict Development and Outcome of Sepsis-Associated Encephalopathy in Pediatrics With Severe Sepsis or Septic Shock

Background and Aim: Sepsis is a common cause of pediatric intensive care unit (ICU) admission. Sepsis-associated encephalopathy (SAE) may occur owing to brain dysfunction in those patients and may be related to impaired cerebral microcirculation. Transcranial Doppler (TCD) can be used to detect this impairment. In this study, we aimed to assess the role of TCD in prediction of SAE and mortality in patients with severe sepsis or septic shock admitted to PICU. Patients and Methods: This prospective study included 75 children admitted to PICU owing to severe sepsis or septic shock. Upon admission, all patients were subjected to careful history taking, thorough clinical examination, and standard laboratory workup. Severity of clinical illness was assessed using the Pediatric Risk of Mortality (PRISM) III score. TCD was performed on the first day of admission after the normalization of systolic blood pressure with or without vasopressors. The primary study outcome was differences in the measurement of TCD in SAE, and the secondary outcome was discharge from ICU or mortality. Results: The study comprised 45 children with SAE and 30 age- and sex-matched children without SAE. In this study, SAE patients had significantly higher pulsatility index [PI; median interquartile range (IQR): 1.15 (0.98-1.48) vs. 1.0 (0.95-1.06), p = 0.002] and resistive index [RI; median (IQR): 0.68 (0.61-0.77) vs. 0.62 (0.59-0.64), p = 0.001] than had non-SAE patients. PI and RI showed good performance as predictors of subsequent SAE development [area under the curve (AUC): 0.72 and 0.73, respectively]. Non-survivors in SAE patients had significantly higher PRISM III. Receiver operating characteristic (ROC) curve analysis showed good performance of PI and RI as predictors of mortality at the end of follow-up. Conclusions: In children with SAE, cerebrovascular resistance is high and is associated with increased mortality.

Experimental sepsis-associated encephalopathy is accompanied by altered cerebral blood perfusion and water diffusion and related to changes in cyclooxygenase-2 expression and glial cell morphology but not to blood-brain barrier breakdown

Sepsis-associated encephalopathy (SAE) refers to brain dysfunction, including delirium, occurs during severe infection and is associated with development of post-traumatic stress disorder. SAE has been proposed to be related to reduced cerebral blood flow (CBF), blood-brain barrier breakdown (BBB), white matter edema and disruption and glia cell activation, but their exact relationships remain to be determined. In the present work, we set out to study CBF using Arterial Spin Labeling (ASL) and grey and white matter structure with T2- and diffusion magnetic resonance imaging (dMRI) in rats with cecal ligation and puncture (CLP)-induced encephalopathy. Using immunohistochemistry, the distribution of the vasoactive prostaglandin-synthesizing enzyme cyclooxygenase-2 (COX-2), perivascular immunoglobulins G (IgG), aquaporin-4 (AQP4) and the morphology of glial cell were subsequently assessed in brains of the same animals. CLP induced deficits in the righting reflex and resulted in higher T2-weighted contrast intensities in the cortex, striatum and at the base of the brain, decreased blood perfusion distribution to the cortex and increased water diffusion parallel to the fibers of the corpus callosum compared to sham surgery. In addition, CLP reduced staining for microglia- and astrocytic-specific proteins in the corpus callosum, decreased neuronal COX-2 and AQP4 expression in the cortex while inducing perivascular COX-2 expression, but did not induce widespread perivascular IgG diffusion. In conclusion, our findings indicate that experimental SAE can occur in the absence of BBB breakdown and is accompanied by increased water diffusion anisotropy and altered glia cell morphology in brain white matter.

Transcranial Doppler waveform changes due to increased cerebrovascular resistance and raised intracranial pressure in a patient with cirrhosis: A difference in shapes, not in numbers

We report and discuss a case that illustrate the clinical utility of transcranial Doppler (TCD) ultrasound in a patient with cirrhosis. A 43-year-old female presented with acute decompensation of cirrhosis with hepatic encephalopathy, requiring mechanical ventilation. TCD showed low diastolic flow velocities and high pulsatility index (PI) consistent with increased cerebrovascular resistance (CVR). The flow velocities and PI normalized over a period of few days and correlated well with neurological improvement after treatment. Subsequently, the patient developed a large intracerebral hemorrhage with mass effect. The TCD measurements in intracranial hypertension were similar to those with cirrhosis and hepatic encephalopathy. However, the windkessel notch in the systolic phase of TCD waveform, related to the distensibility of arterial wall, was absent during raised intracranial pressure (ICP). The absence of a windkessel notch may help to differentiate a high downstream resistance due to raised ICP from increased CVR.

Transcranial Doppler ultrasound in posterior reversible encephalopathy syndrome: A case report

I describe a case and brief discussion to illustrate the clinical utility of transcranial Doppler ultrasound in suspected posterior reversible encephalopathy syndrome. A 26-year-old female presented with headache, visual disturbance, dyspnoea and hypertension. Past medical history included heart transplantation and hypertension. Cytomegalovirus pneumonia with acute respiratory distress syndrome was diagnosed requiring mechanical ventilation and extracorporeal membrane oxygenation. A brain computed tomographic scan showed changes suggestive of posterior reversible encephalopathy syndrome. Transcranial Doppler showed increased velocities with low pulsatility index consistent with cerebral hyperaemia. After antihypertensive treatment flow velocities and computed tomography normalised with complete clinical recovery.

Variation of Cognitive Function During a Short Stay at Hypobaric Hypoxia Chamber (Altitude: 3842 M)

Objective

To observe the effects of a fast-acute ascent to high altitude on brain cognitive function and transcranial doppler parameters in order to understand the physiological countermeasures of hypoxia.

Methods

17 high-altitude-naïve male subjects (mean age was 26.3 ± 8.1 years) participated in the study. We measured Critical Flicker Fusion Frequency (CFFF), blood oxygen saturation, Psychology Experiment Building (PEBL) including three tests (Modified Math Processing Task, Perceptual Vigilance Task, and Time Estimation Task), as well as Cerebral Blood Flow index (CBFi), mean cerebral artery Systolic and diastolic velocities, Cerebral Pulsatility index (CPi), and heart Rate. All were measured at sea level, at least 1 h after arrival at the hypobaric hypoxia equivalent of 3842 m and 1 h after return to sea level.

Results

Under acute exposure to hypobaric hypoxic conditions, significant decrease in CFFF [42.1 ± 1 vs. 43.5 ± 1.7 Hz at sea level (asl), p < 0.01], CBFi (611 ± 51 vs. 665 ± 71 asl, p < 0.01) and blood oxygen saturation (83 ± 4% vs. 98 ± 1% asl, p < 0.001) as compared to pre-ascent values were observed. Physiological countermeasures to hypoxia could be involved as there was no significant change in neuropsychometric tests, Systolic and Diastolic velocities and CPi. A significant increase in Heart Rate (81 ± 15 bpm vs. 66 ± 15 bpm asl, p < 0.001) was observed. All parameters returned to their basal values 1 h after regaining sea level.

Conclusion

Hypoxia results in a decrease in CFFF, CBFi and oxygen saturation and in an increase in heart rate. As it decreased, Cerebral Blood Flow index does not seem to be the physiological measurement of choice to hypoxia explaining the maintenance of cognitive performance after acute exposure to hypobaric hypoxia and requires further investigation. Cerebral oxygen delivery and extraction could be one of the underlying mechanisms.

Septic Encephalopathy

PURPOSE OF THE REVIEW

To discuss the diagnostic approach to patients with septic encephalopathy as well as the need for specific neuro-monitoring and the perspectives on future therapeutic approaches in this setting.

RECENT FINDINGS

Most of data-concern experimental studies evaluating the pathophysiology of septic encephalopathy. A combination of neurodegenerative pathways with neurovascular injury is the cornerstone for the development of such complication and the long-term neurological sequelae among survivors. Septic encephalopathy is a common complication in septic patients. Clinical presentation may range from mild confusion and disorientation to convulsions and deep coma. The diagnosis of septic encephalopathy is made difficult by the lack of any specific clinical and non-clinical feature, in particular among sedated patients in whom neurological examination is unreliable. In spite of the high mortality rate associated with this condition, there is no prophylactic or targeted therapy to reduce or minimize brain damage in septic patients and clinical management is limited to the treatment of the underlying infection.

Impact of fluid challenge increase in cardiac output on the relationship between systemic and cerebral hemodynamics in severe sepsis compared to brain injury and controls

Background

Cognitive dysfunction and delirium after ICU are frequent and may partially result from brain ischemia episodes. We hypothesized that systemic inflammation (severe sepsis or septic shock) modifies the control of brain circulation and the relation between systemic and cerebral hemodynamic after a positive response to fluid challenge (FC).

Methods

Three groups of patients were studied if they increased stroke volume (SV) > 10% after 250 or 500 ml of crystalloids: control group: patients free of comorbidity anesthetized for orthopedic surgery; sepsis group: patients with severe sepsis or septic shock (classic definition); brain injury (BI) group: trauma brain jury or hemorrhagic stroke with no detectable systemic inflammation. The measurements before and after FC were mean arterial blood pressure (MAP) (radial catheter); SV and cardiac output (CO; transesophageal Doppler); bilateral middle cerebral artery (MCAv) velocity with peak systolic (PSV) and end diastolic (EDV) values (transcranial Doppler); end-tidal CO₂. The role of MAP increase was investigated by an arbitrarily threshold increase of 5%, called responder in CO and MAP (RR). The remaining patients were call responders in CO and non-responders in MAP (RnR). Nonparametric tests were used for statistical analysis.

Results

Among the 86 screened patients, 66 have completed the protocol: 17 in control group; 38 in sepsis group; and 11 in BI group. All patients increased SV > 10% after FC. Only the sepsis group increased MAP [+ 12 (2–25%), p < 0.05] with a significant increase in PSV and EDV [(17 (3–30)% and 17 (12–42)%, respectively (p < 0.05)], which did not change in the two other groups. The septic RR or RnR had similar variations in MCAv after FC. The baseline MAP < or > baseline median MAP had similar MCAv.

Conclusions

After a FC-induced increase in SV, MCAv (PSV and EDV) increased only in septic group, mostly independently from MAP increase and from baseline MAP level. Cerebral perfusion becomes passively dependent on systemic blood flow, suggesting a modification of the control of cerebrovascular tone in sepsis-induced systemic inflammation. This information has been considered in the clinical management of septic patients.

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0419-1) contains supplementary material, which is available to authorized users.

Fluid Resuscitation in Septic Patients Improves Systolic but not Diastolic Middle Cerebral Artery Flow Velocity

To investigate the effects of fluid resuscitation on cerebral hemodynamics in sepsis, the following set of transcranial Doppler (TCD) parameters was used: maximal change in flow velocity (FV) during stroke onset (acc), maximal FV during first (sys1) or second (sys2) phase of systole and mean diastolic FV (dias@560). We aim to evaluate changes in cerebral hemodynamics that result from (i) sepsis and (ii) adequate fluid resuscitation in critically ill septic patients. In the majority of 16 septic patients sys2 was initially absent but reappeared during the period of fluid resuscitation; whereas sys2 absence was never seen in healthy controls. Second, adequate fluid resuscitation resulted in a significant increase of the systolic FV components (acc, sys1, sys2 and systolic blood pressure); whereas the diastolic components (dias@560 and diastolic blood pressure) remained unchanged. Sys2 absence and reappearance in sepsis suggests that TCD could become a non-invasive alternative for hemodynamic monitoring.

Transcranial Doppler: a stethoscope for the brain-neurocritical care use

Transcranial Doppler (TCD) ultrasonography is a noninvasive bedside monitoring technique that can evaluate cerebral blood flow hemodynamics in the intracranial arterial vasculature. TCD allows assessment of linear cerebral blood flow velocity, with a high temporal resolution and is inexpensive, reproducible, and portable. The aim of this review is to provide an overview of the most commonly used TCD derived signals and measurements used commonly in neurocritical care. We describe both basic (flow velocity, pulsatility index) and advanced concepts, including critical closing pressure, wall tension, autoregulation, noninvasive intracranial pressure, brain compliance, and cerebrovascular time constant; we also describe the clinical applications of TCD to highlight their utility in the diagnosis and monitoring of cerebrovascular diseases as the "stethoscope for the brain."

Assessment of cerebral circulation in a porcine model of intravenously given E. coli induced fulminant sepsis

BACKGROUND

The aim of the present work was to assess cerebral hemodynamic changes in a porcine model of E.coli induced fulminant sepsis.

METHODS

Nineteen healthy female Hungahib pigs, 10-12 weeks old, randomly assigned into two groups: Control (n = 9) or Septic Group (n = 10). In the Sepsis group Escherichia coli culture suspended in physiological saline was intravenously administrated in a continuously increasing manner according to the following protocol: 2 ml of bacterial culture suspended in physiological saline was injected in the first 30 min, then 4 ml of bacterial culture was administered within 30 min, followed by infusion of 32 ml bacterial culture for 2 h. Control animals received identical amount of saline infusion. Systemic hemodynamic parameters were assessed by PiCCo monitoring, and cerebral hemodynamics by transcranial Doppler sonography (transorbital approach) in both groups.

RESULTS

In control animals, systemic hemodynamic variables and cerebral blood flow velocities and pulsatility indices were relatively stable during the entire procedure. In septic animals shock developed in 165 (IQR: 60-255) minutes after starting the injection of E.coli solution. Blood pressure values gradully decreased, whereas pulse rate increased. A decrease in cardiac index, an increased systemic vascular resistance, and an increased stroke volume variation were observed. Mean cerebral blood flow velocity in the middle cerebral artery did not change during the procedure, but pulsatility index significantly increased.

CONCLUSIONS

There is vasoconstriction at the level of the cerebral arterioles in the early phase of experimental sepsis that overwhelmes autoregulatory response. These results may serve as additional pathophysiological information on the cerebral hemodynamic changes occurring during the septic process and may contribute to a better understanding of the pathomechanism of septic encephalopathy.

Cerebral perfusion alterations and cognitive decline in critically ill sepsis survivors

INTRODUCTION

We investigated the association between cerebral perfusion perturbations in sepsis with possible cognitive decline (CD) after patients' discharge from the intensive care unit (ICU).

METHODS

We studied 28 patients with sepsis and Lawton's Instrumental Activities of Daily Living scale (IADL) scores ≥5 who were discharged from a university ICU institution. We evaluated cerebral circulatory parameters (pulsatility index (PI) and cerebral blood flow index (CBFi) was calculated based on the measured velocity of the middle cerebral artery. Use of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) test was performed daily, and either the Mini Mental State Examination test (MMSE) or Clock Drawing test was performed at ICU discharge. CD was categorized as persistent coma, positive CAM-ICU test at discharge, MMSE <24, or an abnormal Clock test.

RESULTS

Patients had a median pre-ICU IADL score of 6.3 (95% CI 5.9-6.7). Fourteen patients (50%) had CD at discharge. Two were in persistent coma despite sepsis resolution. Information recall was the most affected mental function of the other 12 patients. Only on the first day, patients with CD had higher PI and lower CBFi compared to those without CD (2.2 ± 0.7 vs. 1.4 ± 0.5, p = 0.02; 363 ± 170 vs. 499 ± 133, p = 0.03, respectively). Multivariable analysis revealed delirium, but not PI, as an independent prognostic factor for CD (OR: 29.62, 95%CI 1.91-458.01, p = 0.01).

CONCLUSION

Delirium, but not cerebral perfusion alterations, is an independent risk factor for cognitive impairment in septic patients who were discharged from the ICU.

Cerebral hemodynamics in sepsis assessed by transcranial Doppler: a systematic review and meta-analysis

Cerebral microcirculation is gradually compromised during sepsis, with significant reductions in the function of capillaries and blood perfusion in small vessels. Transcranial Doppler ultrasound (TCD) has been used to assess cerebral circulation in a typical clinical setting. This study was to systematically review TCD studies, assess their methodological quality, and identify trends that can be associated with the temporal evolution of sepsis and its clinical outcome. A meta-analysis of systematic reviews was conducted according to the PRISMA statement. Articles were searched from 1982 until the conclusion of this review in December 2015. Twelve prospective and observational studies were selected. Evaluations of cerebral blood flow, cerebral autoregulation, and carbon dioxide (CO₂) vasoreactivity were summarized. A temporal pattern of the evolution of the illness was found. In early sepsis, the median blood flow velocity (Vm) and pulsatility index (PI) increased, and the cerebral autoregulation (CA) remained unchanged. In contrast, Vm normalization, PI reduction and CA impairment were found in later sepsis (patients with severe sepsis or septic shock). Cerebral haemodynamic is impaired in sepsis. Modifications in cerebral blood flow may be consequence to the endothelial dysfunction of the microvasculature induced by the release of inflammatory mediators. A better understanding of cerebral hemodynamics may improve the clinical management of patients with sepsis and, consequently, improve clinical outcomes.

Increased pulsatility of the intracranial blood flow spectral waveform on transcranial Doppler does not point to peripheral arterial disease in stroke patients

BACKGROUND

Peripheral arterial disease (PAD) is common in patients with acute cerebral ischemia. Indexes of resistance derived from the systolic and diastolic velocities are routinely used in diagnostic transcranial Doppler (TCD) to detect intracranial arterial disease. We sought to explore whether these indexes can predict the presence of PAD in acute cerebral ischemia.

METHODS

We prospectively evaluated consecutive patients with acute cerebral ischemia. On TCD, peak-systolic and end-diastolic velocities in both middle cerebral and basilar arteries were manually measured to calculate pulsatility index (PI) and resistance index (RI). Increased resistance was defined as PI equal to 1.2 or more and RI equal to .75 or more. Ankle-brachial index (ABI) measurements were performed and an ABI equal to .9 or more was considered predictive of definite PAD.

RESULTS

We included 95 patients (45 male, 50 female) aged 66 ± 9 years with a median National Institutes Health Stroke Scale score of 3 (interquartile range, 8) points. The ABI was abnormal and consistent with definite PAD in 24 of 95 (25.3%; 95% confidence interval [CI], 16.4-34.2) patients. Increased PI did not differ among patients with and without PAD (20.8% vs. 28.2%, P = .60). Only 1 patient with PAD had increased RI as opposed to 4 patients without PAD (4.2% vs. 5.6%, P = 1.0). Increased PI was not found to be an independent predictor of PAD (odds ratio [OR], .68; 95% CI, .22-2.12; P = .51). Increases in both PI and RI independently predicted arterial hypertension (OR, 1.62; 95% CI, 1.19-2.21; P = .002 and OR, 3.20; 95% CI, 1.51-6.77; P = .002, respectively).

CONCLUSIONS

Our findings indicate that PAD cannot be inferred from intracranial flow parameters predictive of arterial disease and risk factors such as hypertension among patients with acute cerebral ischemia.

Transcranial Doppler to assess sepsis-associated encephalopathy in critically ill patients

Background

Transcranial Doppler can detect cerebral perfusion alteration in septic patients. We correlate static Transcranial Doppler findings with clinical signs of sepsis-associated encephalopathy.

Methods

Forty septic patients were examined with Transcranial Doppler on the first and third day of sepsis diagnosis. The pulsatility index (PI) and cerebral blood flow index (CBFi) were calculated by blood velocity in the middle cerebral artery (cm/sec). Patients underwent a daily cognitive assessment with the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) test.

Results

Twenty-one patients (55%) were found to present confusion. The majority of the patients presented a PI > 1.1 (76%). PI on the first day (but not the third day) could predict a positive CAM-ICU test in septic patients (PI cut-off: 1.3, AUC: 0.905, p < 0.01, sensitivity: 95%, specificity: 88%, AUC: 0.618, p = 0.24). Multivariable analysis showed that PI on the first day is related to a positive CAM-ICU test independent of age and APACHE II score (OR: 5.6, 95% CI: 1.1-29, p = 0.03). A decrease of the PI on the third day was observed in the group that presented initially high PI (>1.3) (2.2 ± 0.71 vs. 1.81 ± 0.64; p = 0.02). On the other hand, an increase in PI was observed in the other patients (1.01 ± 0.15 vs. 1.58 ± 0.57; p < 0.01). On only the first day, the mean blood velocity in the middle cerebral artery and CBFi were found to be lower in those patients with a high initial PI (36 ± 21 vs. 62 ± 28 cm/sec; p < 0.01, 328 ± 101 vs. 581 ± 108; p < 0.01, respectively).

Conclusions

Cerebral perfusion disturbance observed with Transcranial Doppler could explain clinical symptoms of sepsis-associated encephalopathy.