Transcranial Doppler as a screening test to exclude intracranial hypertension in brain-injured patients: the IMPRESSIT-2 prospective multicenter international study.

BACKGROUND: Alternative noninvasive methods capable of excluding intracranial hypertension through use of transcranial Doppler (ICPtcd) in situations where invasive methods cannot be used or are not available would be useful during the management of acutely brain-injured patients. The objective of this study was to determine whether ICPtcd can be considered a reliable screening test compared to the reference standard method, invasive ICP monitoring (ICPi), in excluding the presence of intracranial hypertension. METHODS: This was a prospective, international, multicenter, unblinded, diagnostic accuracy study comparing the index test (ICPtcd) with a reference standard (ICPi), defined as the best available method for establishing the presence or absence of the condition of interest (i.e., intracranial hypertension). Acute brain-injured patients pertaining to one of four categories: traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), intracerebral hemorrhage (ICH) or ischemic stroke (IS) requiring ICPi monitoring, were enrolled in 16 international intensive care units. ICPi measurements (reference test) were compared to simultaneous ICPtcd measurements (index test) at three different timepoints: before, immediately after and 2 to 3 h following ICPi catheter insertion. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated at three different ICPi thresholds (> 20, > 22 and > 25 mmHg) to assess ICPtcd as a bedside real-practice screening method. A receiver operating characteristic (ROC) curve analysis with the area under the curve (AUC) was used to evaluate the discriminative accuracy and predictive capability of ICPtcd. RESULTS: Two hundred and sixty-two patients were recruited for final analysis. Intracranial hypertension (> 22 mmHg) occurred in 87 patients (33.2%). The total number of paired comparisons between ICPtcd and ICPi was 687. The NPV was elevated (ICP > 20 mmHg = 91.3%, > 22 mmHg = 95.6%, > 25 mmHg = 98.6%), indicating high discriminant accuracy of ICPtcd in excluding intracranial hypertension. Concordance correlation between ICPtcd and ICPi was 33.3% (95% CI 25.6-40.5%), and Bland-Altman showed a mean bias of -3.3 mmHg. The optimal ICPtcd threshold for ruling out intracranial hypertension was 20.5 mmHg, corresponding to a sensitivity of 70% (95% CI 40.7-92.6%) and a specificity of 72% (95% CI 51.9-94.0%) with an AUC of 76% (95% CI 65.6-85.5%). CONCLUSIONS AND RELEVANCE: ICPtcd has a high NPV in ruling out intracranial hypertension and may be useful to clinicians in situations where invasive methods cannot be used or not available. TRIAL REGISTRATION: NCT02322970 .

Noninvasive Intracranial Pressure Estimation With Transcranial Doppler: A Prospective Observational Study.

BACKGROUND: Transcranial Doppler (TCD) ultrasonography has been described for the noninvasive assessment of intracranial pressure (ICP). This study investigates the relationship between standard, invasive intracranial pressure monitoring (ICPi) and noninvasive ICP assessment using a simple formula based on TCD-derived flow velocity (FV) and mean arterial blood pressure values (ICPTCD). MATERIAL AND METHODS: We performed a prospective observational study on 100 consecutive traumatic brain injury patients requiring invasive ICP monitoring, admitted to the Neurosciences and Trauma Critical Care Unit of Addenbrooke's Hospital, Cambridge, UK. ICPi was compared with ICPTCD using a method based on the "diastolic velocity-derived estimator" (FVd), which was initially described for the noninvasive estimation of cerebral perfusion pressure but subsequently utilized for ICP assessment. RESULTS: Median ICPi was 13 mm Hg (interquartile range: 10, 17.25 mm Hg). There was no correlation between ICPi and ICPTCD (R=-0.17; 95% confidence interval [CI]: -0.35, 0.03; P=0.097). Bland-Altman analysis demonstrated wide 95% limits of agreement between ICPi and ICPTCD (-27.58, 30.10; SD, 14.42). ICPTCD was not able to detect intracranial hypertension (ICPi >20 mm Hg); the area under the receiver operating characteristic curve for prediction was 34.5% (95% CI, 23.1%-45.9%) with 0% sensitivity and 74.4% specificity for ICPTCD to detect ICPi>20 mm Hg. CONCLUSIONS: Using a formula based on diastolic FV, TCD is an insufficiently accurate method for the noninvasive assessment of ICP. Further studies are warranted to confirm these results in a broader patient cohort.

A Modified Translaryngeal Tracheostomy Technique in the Neurointensive Care Unit. Rationale and Single-center Experience on 199 Acute Brain-damaged Patients.

BACKGROUND: Brain-injured patients frequently require tracheostomy, but no technique has been shown to be the gold standard for these patients. We developed and introduced into standard clinical practice an innovative bedside translaryngeal tracheostomy (TLT) technique aided by suspension laryngoscopy (modified TLT). During this procedure, the endotracheal tube is left in place until the airway is secured with the new tracheostomy. This study assessed the clinical impact of this technique in brain-injured patients. MATERIALS AND METHODS: This is a retrospective analysis of prospectively collected data from adult brain-injured patients who had undergone modified TLT during the period spanning from January 2010 to December 2016 at the Neurointensive care unit, San Gerardo Hospital (Monza, Italy). The incidence of intraprocedural complications, including episodes of intracranial hypertension (intracranial pressure [ICP] >20 mm Hg), was documented. Neurological, ventilatory, and hemodynamic parameters were retrieved before, during, and after the procedure. Risk factors for complications and intracranial hypertension were assessed by univariate logistic analysis. Data are presented as n (%) and median (interquartile range) for categorical and continuous variables, respectively. RESULTS: A total of 199 consecutive brain-injured patients receiving modified TLT were included. An overall 52% male individuals who were 66 (54 to 74) years old and who had an admission Glasgow Coma Scale of 7 (6 to 10) were included in the cohort. Intracerebral hemorrhage (30%) was the most frequent diagnosis. Neurointensivists performed 130 (65%) of the procedures. Patients underwent tracheostomy 10 (7 to 13) days after intensive care unit admission. Short (ie, <2 min) and clinically uneventful increases in ICP>20 mm Hg were observed in 11 cases. Overall, the procedure was associated with an increase in ICP from 7 (4 to 10) to 12 (7 to 18) mm Hg (P<0.001). Compared with baseline, cerebral perfusion pressure (CPP), respiratory variables, and hemodynamics were unchanged during the procedure (P-value, not significant). Higher baseline ICP and core temperature were associated with an increased risk of complications and intracranial hypertension. Complication rates were low: 1 procedure had to be converted to a surgical tracheostomy, and 1 (0.5%) episode of minor bleeding and 5 (2.5%) of minor non-neurological complications were recorded. Procedures performed by intensivists did not have a higher risk of complications compared with those performed by ear, nose, and throat specialists. CONCLUSIONS: A modified TLT (by means of suspension laryngoscopy) performed by neurointensivists is feasible in brain-injured patients and does not adversely impact ICP and CPP.