Performance of the transcranial doppler
SEVERE PREECLAMPSIA
Transcranial doppler assessment was performed between the time of documented severe preeclampsia and study medication administration as a baseline measurement and then it was repeated post-treatment at one and six hours after drug administration.All subjects were rest in left lateral position (15° left lateral recumbency) then after contact gel application, the 1–5 MHz ultrasound probe of Siemens Acuson X300 machine was placed between the ear and lateral orbital margin above the zygomatic bone on the temporal squama (the temporal window) to identify the middle cerebral artery (MCA). Measurements were performed bilaterally whenever possible, and the average value was calculated and recorded. If only one vessel is insonated, this value was used. All the measurements were taken by the same physician who is experienced in neurosonology and blinded to the study purpose.The middle cerebral artery TCD measurements were the mean velocity (MV), the mean end-diastolic velocity (DIAS), and the pulsatility index (PI). The cerebral perfusion pressure (CPP) was estimated using the equation described by Aaslid et al which was validated in pregnant females [Middle cerebral artery velocity (MCA velocity) which is the middle cerebral blood flow component of the CPP formula (mean velocity / (mean velocity – diastolic velocity) was extracted and recorded to examine the impact of cerebral blood flow versus peripheral blood pressure on CPP changes.