In vivoquantification of intraventricular hemorrhage in a neonatal piglet model using an EEG-layout based electrical impedance tomography array

Abstract

Intraventricular hemorrhage (IVH) is a common occurrence in the days immediately after premature birth. It has been correlated with outcomes such as periventricular leukomalacia (PVL), cerebral palsy and developmental delay. The causes and evolution of IVH are unclear; it has been associated with fluctuations in blood pressure, damage to the subventricular zone and seizures. At present, ultrasound is the most commonly used method for detection of IVH, but is used retrospectively. Without the presence of adequate therapies to avert IVH, the use of a continuous monitoring technique may be somewhat moot. While treatments to mitigate the damage caused by IVH are still under development, the principal benefit of a continuous monitoring technique will be in investigations into the etiology of IVH, and its associations with periventricular injury and blood pressure fluctuations. Electrical impedance tomography (EIT) is potentially of use in this context as accumulating blood displaces higher conductivity cerebrospinal fluid (CSF) in the ventricles. We devised an electrode array and EIT measurement strategy that performed well in detection of simulated ventricular blood in computer models and phantom studies. In this study we describe results of pilot in vivo experiments on neonatal piglets, and show that EIT has high sensitivity and specificity to small quantities of blood (<1 ml) introduced into the ventricle. EIT images were processed to an index representing the quantity of accumulated blood (the ‘quantity index’, QI). We found that QI values were linearly related to fluid quantity, and that the slope of the curve was consistent between measurements on different subjects. Linear discriminant analysis showed a false positive rate of 0%, and receiver operator characteristic analysis found area under curve values greater than 0.98 to administered volumes between 0.5, and 2.0 ml. We believe our study indicates that this method may be well suited to quantitative monitoring of IVH in newborns, simultaneously or interleaved with electroencephalograph assessments.

EIT Imaging of Intracranial Hemorrhage in Rabbit Models Is Influenced by the Intactness of Cranium

“…Besides the cranium and blood, the injection site may also result in the different impedance changes within brain. For instance, when the blood was injected into cerebral ventricle [19] or subarachnoid space [20], which is full of CSF, the corresponding impedance gain was observed on EIT images; the possible reason may lie in the lower impedance of CSF than blood. Thus in future study, it is necessary to be aware of the blood injection site and consider the interaction among blood, parenchyma, and CSF, as well as their effects on the relevant impedance changes of brain.…”

“…This finding was also observed by Dowrick et al [17] who injected autologous blood into rat brain with the closed cranium. On the other hand, Sadleir et al [18] and Tang et al [19] employed EIT to monitor ICH in the open/closed cranium pig model of intraventricular hemorrhage and found that brain impedance increased with the amount of blood injected. Dai et al [20] also reported an increase in brain impedance when autologous blood was injected into subarachnoid space in the closed cranium pig models.…”

Near‐field impedance accurately distinguishes among pericardial, intracavitary, and anterior mediastinal position

“…10 Bioimpedance is an increasingly used tool with multiple medical applications, including estimating volume status in patients with heart failure, detecting cancer, and monitoring patients for internal bleeding complications after percutaneous femoral access. [11][12][13][14] In these scenarios, bioimpedance has proved accurate in detecting small changes in tissue composition.…”

Opportunities in posthemorrhagic hydrocephalus research: outcomes of the Hydrocephalus Association Posthemorrhagic Hydrocephalus Workshop

“…There is a wide range of animal models used for research in PHH of prematurity and germinal matrix hemorrhage (reviewed in [ 233 , 234 ]), and no single animal model will be suitable for all biological questions. Most studies involve experimental induction of IVH in mice [ 67 , 191 , 235 ], rats [ 182 , 185 , 202 , 236 – 243 ], rabbits [ 244 – 250 ], cats [ 251 ], dogs [ 252 , 253 ], sheep [ 254 ], and pigs [ 255 – 258 ]. While the majority of these in vivo studies have employed intraventricular injection of whole blood or blood products, others have used alternative approaches [ 67 , 247 , 259 – 261 ].…”