Evaluation of cerebral hemodynamics by transcranial Doppler ultrasonography and its correlation with intracranial pressure in an animal model of intracranial hypertension

Abstract

Background: Transcranial Doppler has been tested in the evaluation of cerebral hemodynamics as a non-invasive assessment of intracranial pressure (ICP), but there is controversy in the literature about its actual benefit and usefulness in this situation. Objective: To investigate cerebral blood flow assessed by Doppler technique and correlate with the variations of the ICP in the acute phase of intracranial hypertension in an animal model. Methods: An experimental animal model of intracranial hypertension was used. The experiment consisted of two groups of animals in which intracranial balloons were implanted and inflated with 4 mL (A) and 7 mL (B) for controlled simulation of different volumes of hematoma. The values of ICP and Doppler parameters (systolic [FVs], diastolic [FVd], and mean [FVm] cerebral blood flow velocities and pulsatility index [PI]) were collected during the entire procedure (before and during hematoma simulations and venous hypertonic saline infusion intervention). Comparisons between Doppler parameters and ICP monitoring were performed. Results: Twenty pigs were studied, 10 in group A and 10 in group B. A significant correlation between PI and ICP was obtained, especially shortly after abrupt elevation of ICP. There was no correlation between ICP and FVs, FVd or FVm separately. There was also no significant change in ICP after intravenous infusion of hypertonic saline solution. Conclusions: These results demonstrate the potential of PI as a parameter for the evaluation of patients with suspected ICP elevation.

Assessing ultrasonographic optic nerve sheath diameter in animal model with anesthesia regimens

“…ONSUS was performed in two opportunities with an average of 10 minutes of interval. The first measure at sedation induction with xylazine and ketamine, the second immediately after endotracheal intubation and administration of propofol or thiopental in concentrations adjusted for animals' weight in order to produce deep sedation 4 .…”

“…These devices are invasive and can cause complications, including infections and bleeding. However, estimation and monitoring of ICP is feasible by means of noninvasive techniques [1][2][3][4] .…”

Noninvasive methods to monitor intracranial pressure

“…Several parameters of transcranial Doppler (TCD) ultrasound, such as cerebral blood flow velocity (CBV), pulsatility index, and the ability to measure the diameter of the optic nerve sheath (discussed in a later section), have been studied as noninvasive biomarkers of ICP [84][85][86]. Although several early studies and a few recent studies have shown a strong correlation between TCD and ICP [87], a number of studies have shown varying correlations between TCD-determined ICP and invasively obtained ICP or have failed to show a correlation [84,[88][89][90][91].…”

Animal models for the study of intracranial hematomas (Review)

“…Regarding the animals used for modeling ICH, the following different species were used: Mice or rats (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33), pigs (34)(35)(36)(37)(38)(39)(40), dogs (41)(42)(43), monkeys (44), sheep (45), cats (46) and rabbits (47,48). The majority of studies (63%) utilized rats, whereas the model most used is autologous blood intracranial injection (51%).…”

“…Studies for ultrasound assessment of the optic nerve sheath diameter ( 34 , 94 ) and transcranial Doppler pulsatility index ( 35 ) have taken advantage of this method because of sudden IHT development. Thus, the balloon model appears to be sufficient for generating oscillations in intracranial pressure measurements as well as for causing an impact on cerebral hemodynamic conditions and valuable for studying the effects of mechanical damage to the brain tissue ( 43 ).…”