Prospective Study on Noninvasive Assessment of Intracranial Pressure in Traumatic Brain-Injured Patients: Comparison of Four Methods

Abstract

Elevation of intracranial pressure (ICP) may occur in many diseases, and therefore the ability to measure it noninvasively would be useful. Flow velocity signals from transcranial Doppler (TCD) have been used to estimate ICP; however, the relative accuracy of these methods is unclear. This study aimed to compare four previously described TCD-based methods with directly measured ICP in a prospective cohort of traumatic brain-injured patients. Noninvasive ICP (nICP) was obtained using the following methods: 1) a mathematical ''black-box'' model based on interaction between TCD and arterial blood pressure (nICP_BB); 2) based on diastolic flow velocity (nICP_FVd); 3) based on critical closing pressure (nICP_CrCP); and 4) based on TCD-derived pulsatility index (nICP_PI). In time domain, for recordings including spontaneous changes in ICP greater than 7 mm Hg, nICP_PI showed the best correlation with measured ICP (R = 0.61). Considering every TCD recording as an independent event, nICP_BB generally showed to be the best estimator of measured ICP (R = 0.39; p < 0.05; 95% confidence interval [CI] = 9.94 mm Hg; area under the curve [AUC] = 0.66; p < 0.05). For nICP_FVd, although it presented similar correlation coefficient to nICP_BB and marginally better AUC (0.70; p < 0.05), it demonstrated a greater 95% CI for prediction of ICP (14.62 mm Hg). nICP_CrCP presented a moderate correlation coefficient (R = 0.35; p < 0.05) and similar 95% CI to nICP_BB (9.19 mm Hg), but failed to distinguish between normal and raised ICP (AUC = 0.64; p > 0.05). nICP_PI was not related to measured ICP using any of the above statistical indicators. We also introduced a new estimator (nICP_Av) based on the average of three methods (nICP_BB, nICP_FVd, and nICP_CrCP), which overall presented improved statistical indicators (R = 0.47; p < 0.05; 95% CI = 9.17 mm Hg; AUC = 0.73; p < 0.05). nICP_PI appeared to reflect changes in ICP in time most accurately. nICP_BB was the best estimator for ICP ''as a number.'' nICP_Av demonstrated to improve the accuracy of measured ICP estimation.

Can intracranial pressure be measured non-invasively bedside using a two-depth Doppler-technique?

“…In two recent studies, Cardim et al compared four methods used for non invasive ICP estimation using both arterial blood pressure and flow velocity as inputs. In a cohort of traumatic brain-injured patients [25] and in a group of patients investigated with infusion tests [26], limits of agreements were larger than ±9 mmHg in all four methods.…”

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

“…The method had a high positive predictive power (94%) for detecting low CPP (< 60 mmHg). The same method was applied in clinical and experimental studies (Robba et al, ; Cardim et al, ; Rasulo et al, ) with promising results.…”

Avaliação da hemodinâmica cerebral através da técnica de ultrassonografia Doppler e suas correlações com as variações da pressão intracraniana em um modelo animal de hipertensão intracraniana

“…Em (Bellner et al, 2004;Cardim et al, 2017). Já outros trabalhos encontraram uma fraca correlação entre PIC e IP, concluindo ser este um método limitado para tal fim (Behrens et al, 2010;Cardim et al, 2016c;Morgalla e Magunia et al, 2016;Zweifel et al, 2012;).…”

“…Por isso, nos últimos anos, há um grande número de estudos que visam a desenvolver diversas técnicas não invasivas para estimação da PIC (Bellner et al, 2004;Cardim et al, 2016c;Robba et al, 2017;Roh e Park 2016).…”

“…Dentre estas técnicas se destaca o estudo do DTC, com ênfase no IP como parâmetro de estimação não invasiva da PIC (Bellner et al, 2004;Bouzat et al, 2016;Cardim et al, 2016aCardim et al, e 2016b Outros trabalhos também obtiveram resultados positivos referentes à correlação da PIC com o IP em pacientes com lesões cerebrais (Czosnyka et al, 1998;Voulgaris et al, 2005;Melo et al, 2011;de Riva et al, 2012;Wang et al, 2014;Wakerley et al, 2014;O'Brien et al, 2015 (Hanlo et al, 1995;Zweifel et al, 2012;Cardim et al, 2016c;Morgalla e Magunia, 2016;Robba et al, 2017).…”