|LETTER TO EDITOR
|Year : 2020 | Volume
| Issue : 3 | Page : 224-226
Study of reversal of diastolic blood flow in the middle cerebral artery using doppler ultrasound in the prognostication in sick neonates
Iyer Harohallli Venkatesh1, HV Shubha2, Nagesh Karthik1, Swamy RaviShankar1
1 Consultant Neonatologist, Department of Neonatology, Manipal Hospital, Bengaluru, Karnataka, India
2 DNB Neonatology Trainee, Department of Neonatology, Manipal Hospital, Bengaluru, Karnataka, India
|Date of Submission||22-May-2020|
|Date of Acceptance||02-Jul-2020|
|Date of Web Publication||07-Aug-2020|
Dr. Iyer Harohallli Venkatesh
Manipal Hospital, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Venkatesh IH, Shubha H V, Karthik N, RaviShankar S. Study of reversal of diastolic blood flow in the middle cerebral artery using doppler ultrasound in the prognostication in sick neonates. J Clin Neonatol 2020;9:224-6
|How to cite this URL:|
Venkatesh IH, Shubha H V, Karthik N, RaviShankar S. Study of reversal of diastolic blood flow in the middle cerebral artery using doppler ultrasound in the prognostication in sick neonates. J Clin Neonatol [serial online] 2020 [cited 2020 Sep 27];9:224-6. Available from: http://www.jcnonweb.com/text.asp?2020/9/3/224/291652
Cerebral blood flow (CBF) autoregulation is of paramount importance in maintaining cerebral circulation in sick neonates. Once this is lost, there is an initial increase in the resistive index (RI) followed by a reversal of flow when the neuronal tissue begins to die. The pathogenesis of several neuropathological injuries in the neonatal period is related to CBF impairment, but most of the methods used to assess CBF are technically complex, invasive, or costly. Doppler ultrasonography has been used in several studies to determine CBF velocity in intracranial cerebral arteries of asphyxiated newborns. Cerebral vascular anatomy and disturbance of cerebral hemodynamics are key factors in the pathophysiology of brain injury. Therefore, there is renewed interest in noninvasive methods to evaluate CBF. One such method assessing one aspect of CBF is measuring RI in cerebral arteries using color Doppler imaging. The internal carotid artery, basilar artery, anterior cerebral artery, and lenticulostriate arteries can be easily visualized with color Doppler imaging. The RI has been used to detect intracranial abnormalities including asphyxia, cerebral edema, hydrocephalus, and brain death, and also, low RI is considered a possible sign of luxury perfusion in term birth asphyxia, but not much of the literature found to assess the mortality in sick neonates. Here, we tried to analyze the role of reversal of RI in sick neonates as a marker for impending mortality.
A prospective cohort study was conducted between March 2017 and May 2018 in a tertiary care center. We enrolled 22 sick neonates both term and preterm. Information regarding birth weight, gestational age, gender, mode of delivery, and resuscitation details was collected after obtaining informed written consent. Neonates with major congenital anomalies were excluded from the study.
Infants were examined with cranial ultrasound, including color Doppler imaging. Ultrasound was performed on Philips CX50 using an S 12-4 frequency footprint probe when there was deterioration in hemodynamics. Images were obtained in a transtemporal plane. The middle cerebral artery was visualized using color Doppler, and RI was manually assessed in the aforementioned artery using pulsed-wave Doppler. The RI was defined as (S-D)/S where S is the height of the systolic peak and D is the height of the end-diastolic peak. Normal resistive indices in neonates were taken as 0.6–0.9. Reversal of diastolic flow in a CNS was defined as antegrade flow into the CNS during systole and retrograde flow during diastole, which causes resultant loss of tissue perfusion. The RI was manually assessed in the middle cerebral artery using pulsed-wave Doppler. The mean RI was calculated from average peak systolic velocity and end-diastolic velocity of at least five sequential stable waveforms. Data were collected using MS Excel. Univariate and multivariate analyses were performed to identify prognostic factors for overall survival which was interpreted using Kaplan–Meier curve. Cox regression, log-rank test, hazard ratio (HR), and confidence interval (CI) were calculated, and P value (probability that the result is true) of <0.05 was considered as statistically significant after assuming all the rules of statistical tests. MS Excel using SPSS version 22 (IBM SPSS Statistics, Somers NY, USA) Statistical software was used to analyze the data.
Of the 22 neonates analyzed, 45% of the neonates were <28 weeks of gestation with a mean survival of 26.4 days, as compared to mean survival of 89.04 days in the gestation of more than 37 weeks. There was no statistical significance both in the gender distribution and between the small for gestational and appropriate gestational age neonates. Neonates who had a reversal of diastolic flow had a poor mean survival of 1.3 h when compared to those patients who did not have a reversal of flow of 133.8 days (HR –4.66; 95.0% CI: 1.250–16.96), which was statistically significant (P = 0.001). Furthermore, a birth weight of <1000 g had a mean survival of 29 days compared to more than 2500 g which had a mean survival of 104 days (HR –0.96; 95.0% CI: 0.460–2.032), which also was statistically significant (P < 0.001) [Table 1]. Based on the reversal of diastolic flow, 31.8% of neonates were <28 weeks and 36.3% were <1000 g [Table 2]. There was no statistical significance between gender, mode of delivery, or gestational age. The single most parameter which could signify mortality was a reversal of diastolic flow in the middle cerebral artery (HR –3.00; 95.0% CI: 1.191–7.551), which was statistically significant (P = 0.001) [Table 3].
The pathogenesis involved in neuronal death and injury in a neonate depends mostly on CBF and autoregulation. Autoregulation is a property of arteries to constrict in response to an increase in transmural pressure and to dilate in response to a decrease in pressure, with the effect of keeping blood flow more or less constant with a range of arterial blood pressures. This response has a limited capacity, and as a result, blood flow will decrease when blood pressure decreases below a lower threshold and increase when blood pressure increases above an upper threshold. However, methods used to assess CBF are technically complex, invasive, or costly. Hence, Doppler cranial ultrasound can be used to assess the cerebral autoregulation and this can be calculated using the RI in the cerebral artery. According to our study, the lesser the gestation, the lower was the mean survival. This could be attributed to the fact that our study also included extreme preterm and extremely low birth weight, admitted for comfort care. Higher RI had an adverse outcome which was similar to Argollo et al. Loss of anterograde flow in the middle cerebral artery was associated with the fatal outcome which was similar to a study by Glasier et al. The strength of this study was assessing the cerebral blood through ultrasound Doppler that can help to prognosticate illness in sick neonates. Furthermore, it is noninvasive, quick, and easy to assess. Limitations of the study were that a small cohort was analyzed and more such studies are required before it can be used as a single sign for impending death. Therefore, RI can be used as a surrogate marker for impending mortality and becomes an important parameter to assess in sick neonates.
In an era of the dilemma of diagnosis of fatal outcome in sick neonates, we conclude that reversal of diastolic flow in the cerebral artery can be used as a surrogate marker to assess impending mortality in sick neonates.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]