Effect of oxygen inhalation on cerebral blood flow velocity in premature neonates.
BACKGROUND
The study tested the hypothesis that hyperoxemia and hypoxemia differentially alter cerebral blood flow velocity (CBFV) in a gestational age-dependent manner.


METHODS
Cases comprised 98 neonates with mild respiratory distress, receiving oxygen for >24 h in first 48 h of life. Ninety-eight age- and-weight-matched healthy neonates served as controls. Infants with perinatal asphyxia, shock, sepsis, malformations, acidosis/alkalosis, and hypo/hypercarbia were excluded. Resistance index (RI), pulsatility index (PI), peak systolic flow velocity (PSV), and vascular diameter were measured in internal carotid, vertebral, and middle cerebral arteries by transcranial doppler ultrasonography between 24 and 48 h of life with immediate postdoppler arterial blood gas analysis. For subgroup analysis, neonates were divided by gestational age and PaO2.


RESULTS
An overall decrease in RI/PI and increase in PSV and vasodilation was observed in cases. Hyperoxemia (PaO2 >90 mm Hg) was more common in premature neonates. Neonates <32 wk showed an increase in CBFV (decreased RI/PI and increased PSV/diameter) in association with hyperoxemia. An opposite response was observed in neonates ≥ 32 wk, where CBFV increased in response to hypoxemia (PaO2 <50 mm Hg) and decreased in hyperoxemia. Increased CBFV showed high predictive accuracy for immediate mortality and intracranial hemorrhage.


CONCLUSIONS
Depending on gestational maturity, hyperoxemia or hypoxemia produce differential effects in CBFV.
Division of Neonatology, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Sriparna
S
Basu
Division of Neonatology, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Sandeep
S
Barman
Department of Radiodiagnosis, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Ramchandra
R
Shukla
Division of Neonatology, Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India.
Ashok
A
Kumar
D001783:Blood Flow Velocity; D001921:Brain / Q000098:blood supply*; D002343:Carotid Artery, Internal / Q000473:pathology; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D005260:Female; D005865:Gestational Age; D006801:Humans; D018496:Hyperoxia; D000860:Hypoxia; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D020768:Middle Cerebral Artery / Q000473:pathology; D010100:Oxygen / Q000008:administration & dosage*; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011379:Prognosis; D013997:Time Factors; D014711:Vertebral Artery / Q000473:pathology
D010100:Oxygen