Detection of cerebral hypoperfusion with a dynamic hyperoxia test using brain oxygenation pressure monitoring.

INTRODUCTION: Brain multimodal monitoring including intracranial pressure (ICP) and brain tissue oxygen pressure (PbtO2) is more accurate than ICP alone in detecting cerebral hypoperfusion after traumatic brain injury (TBI). No data are available for the predictive role of a dynamic hyperoxia test in brain-injured patients from diverse etiology. AIM: To examine the accuracy of ICP, PbtO2 and the oxygen ratio (OxR) in detecting regional cerebral hypoperfusion, assessed using perfusion cerebral computed tomography (CTP) in patients with acute brain injury. METHODS: Single-center study including patients with TBI, subarachnoid hemorrhage (SAH) and intracranial hemorrhage (ICH) undergoing cerebral blood flow (CBF) measurements using CTP, concomitantly to ICP and PbtO2 monitoring. Before CTP, FiO2 was increased directly from baseline to 100% for a period of 20 min under stable conditions to test the PbtO2 catheter, as a standard of care. Cerebral monitoring data were recorded and samples were taken, allowing the measurement of arterial oxygen pressure (PaO2) and PbtO2 at FiO2 100% as well as calculation of OxR (= ΔPbtO2/ΔPaO2). Regional CBF (rCBF) was measured using CTP in the tissue area around intracranial monitoring by an independent radiologist, who was blind to the PbtO2 values. The accuracy of different monitoring tools to predict cerebral hypoperfusion (i.e., CBF < 35 mL/100 g × min) was assessed using area under the receiver-operating characteristic curves (AUCs). RESULTS: Eighty-seven CTPs were performed in 53 patients (median age 52 [41-63] years-TBI, n = 17; SAH, n = 29; ICH, n = 7). Cerebral hypoperfusion was observed in 56 (64%) CTPs: ICP, PbtO2 and OxR were significantly different between CTP with and without hypoperfusion. Also, rCBF was correlated with ICP (r = - 0.27; p = 0.01), PbtO2 (r = 0.36; p < 0.01) and OxR (r = 0.57; p < 0.01). Compared with ICP alone (AUC = 0.65 [95% CI, 0.53-0.76]), monitoring ICP + PbO2 (AUC = 0.78 [0.68-0.87]) or ICP + PbtO2 + OxR (AUC = 0.80 (0.70-0.91) was significantly more accurate in predicting cerebral hypoperfusion. The accuracy was not significantly different among different etiologies of brain injury. CONCLUSIONS: The combination of ICP and PbtO2 monitoring provides a better detection of cerebral hypoperfusion than ICP alone in patients with acute brain injury. The use of dynamic hyperoxia test could not significantly increase the diagnostic accuracy.

The Hyperdense Middle Cerebral Artery Sign in Drip-and-Ship Models of Acute Stroke Management.

BACKGROUND: Large vessel occlusion (LVO) leads to debilitating stroke and responds modestly to recombinant tissue plasminogen activator (rt-TPA). Early thrombectomy improves functional outcomes in selected patients with proximal occlusion but it is not available in all medical facilities. The best imaging modality for triage in an acute stroke setting in drip-and-ship models is still the subject of debate. OBJECTIVES: We aimed to assess the diagnostic value of millimeter-sliced noncontrast computed tomography (NCCT) hyperdense middle cerebral artery sign (HMCAS) in itself or associated with clinical data for early detection of LVO in drip-and-ship models of acute stroke management. METHODS: NCCT of patients admitted to the Erasme Hospital, ULB, Brussels, Belgium, for suspicion of acute ischemic stroke between January 1 and July 31, 2017, were collected. Patients with brain hemorrhages were excluded, leading to 122 cases. The presence of HMCAS on NCCT was determined via visual assessment by 6 raters blinded to all other data. An independent rater assessed the presence of LVO on digital subtraction angiography imaging or contrast-enhanced CT angiography (CTA). The sensitivity, false-positive rate (FPR), and accuracy of HMCAS and the dot sign to detect LVO were calculated. The interobserver agreement of HMCAS was assessed using Gwet's AC1 coefficient. Then, on a separate occasion, the first 2 observers rereviewed all NCCT provided with clinical clues. The sensitivity, FPR, and accuracy of HMCAS were recalculated. RESULTS: HMCAS was found in 21% of the cases and a dot sign was found in 9%. The mean HMCAS sensitivity was 62% (95% CI 45-79%) and its accuracy was 86% (95% CI 79-92%) for detecting LVO. The interobserver reliability coefficient was 80% for HMCAS. Combined with clinical information, HMCAS sensitivity increased to 81% (95% CI 68-94; p = 0.041) and accuracy increased to 91% (95% CI 86-96%). CONCLUSION: When clinical data are provided, detection of HMCAS on thinly sliced NCCT could be enough to decide on transfer for thrombectomy in drip-and-ship models of acute stroke management, especially in situations where CTA is less available and referral centers for thrombectomy fewer and further apart.

Reduction of the six-minute walk distance in children with sickle cell disease is correlated with silent infarct: results from a cross-sectional evaluation in a single center in Belgium.

BACKGROUND: The 6-minute walk test (6 MWT) is used in adults and children affected by a wide range of chronic diseases to evaluate their sub-maximal exercise capacity. It reflects the global response of various physiological systems in a situation simulating a daily life activity. METHODS: We analyzed factors affecting the 6 MWT in 46 Sickle Cell Disease children. Forty-two were treated with hydroxyurea (HU). Patients with normal test (>80% of the age-standardized predicted value) were compared to patients with abnormal test (≤ 80%). Baseline hematological values, clinical events, cerebrovascular disease, cardio-pulmonary parameters and disease-modifying treatment were compared according to the performance of the test. RESULTS: Among the 46 patients, 14 had an abnormal 6 MWT. In univariate analysis, both groups were similar for biological and clinical data. Six of the 14 patients with an abnormal 6 MWT had silent infarct (SI) compared to 6/32 with a normal test (P = 0.09). When excluding chronically transfused patients, 4 of the 11 patients with an abnormal 6 MWT had SI compared to 1/26 (P = 0.02). Baseline pulse oximetry was normal in both groups but slightly lower in patients with abnormal 6 MWT (P = 0.02). No patient presented exercise-induced desaturation. In multivariate analysis, the only factor associated with abnormal 6 MWT was the presence of SI (P = 0.045). CONCLUSIONS: In our cohort of 46 patients characterized by high exposure rate to HU and by the absence of severe cardiopulmonary disease, the sole factor independently associated with 6 MWT was the presence of SI. The lower exercise capacity of children with SI may reflect some subclinical neurological impairment as they do not differ by hemoglobin level or cardiopulmonary parameters.