Jong Hee Hwang

The Efficacy of Clinical Strategies to Reduce Nosocomial Sepsis in Extremely Low Birth Weight Infants

The aim of this study was to evaluate the efficacy of clinical strategies to reduce nosocomial sepsis (NS) in extremely low birth weight infants (ELBWI) less than 1,000 g. Data from the period before (P1, 1995-2000) and after (P2, 2001-2002) implementation of the strategies were collected and analyzed. The intervention strategies included restriction of antibiotic therapy, less use of invasive procedures such as umbilical vessel catheterization and endotracheal intubation, establishment of guidelines for hand-washing, infant handling, and central intravascular line management. NS was defined as positive blood cultures in symptomatic patients after the third day of life with the use of antibiotics for more than 5 days. Although the gestational age (GA) and birth weight (BW) were significantly lower in P2 (GA 26.7±2.1 wk; BW 796±130 g) compared to P1 (GA 27.2±1.6 wk; BW 857±121 g), the incidence of NS decreased significantly from 70% (69/99) in P1 to 17% (24/71) in P2 with the implementation of the intervention strategies. The coagulase negative Staphylococcus infection was also significantly reduced from 34% in P1 to 11% in P2. The implementation of the clinical strategies was quite effective in reducing the incidence of NS in ELBWI.

Effects of Hypertonic (7%) Saline on Brain Injury in Experimental Escherichia coli Meningitis

We sought to know whether hypertonic (7%) saline (HTS) attenuates brain injury by improving cerebral perfusion pressure (CPP) and down-modulating acute inflammatory responses in experimental bacterial meningitis in the newborn piglet. Twenty-five newborn piglets were assorted into three groups: 6 in the control group (C), 10 in the meningitis group (M), and 9 in the meningitis with HTS infusion group (H). Meningitis was induced by intracisternal injection of 108 colony forming units of Escherichia coli in 100 µL of saline. 10 mL/kg of HTS was given intravenously as a bolus 6 hr after induction of meningitis, thereafter the infusion rate was adjusted to maintain the serum sodium level between 150 and 160 mEq/L. HTS significantly attenuated meningitis-induced brain cell membrane disintegration and dysfunction, as indicated by increased lipid peroxidation products and decreased Na+, K+-ATPase activity in the cerebral cortex in M. HTS significantly attenuated acute inflammatory markers such as increased intracranial pressure, elevated lactate level and pleocytosis in the cerebrospinal fluid observed in M. Reduced CPP observed in M was also significantly improved with HTS infusion. These findings implicate some attenuation of the meningitis-induced alterations in cerebral cortical cell membrane structure and function with HTS, possibly by improving CPP and attenuating acute inflammatory responses.

Decreasing Incidence of Chronic Lung Disease Despite the Gradual Reduction of Postnatal Dexamethasone Use in Very Low Birth Weight Infants

Dexamethasone has been widely used in very low birth weight infants (VLBWI) weighing less than 1,500 g at birth for the prevention or treatment of chronic lung disease (CLD). Recently, however the use of dexamethasone is being reduced, as its association with abnormal neurodevelopmental outcome is known. On the other hand, there have been persistent concerns about the increased risk of CLD according to the reduction of postnatal dexamethasone use. Hence, we did a retrospective cohort study to delineate the change in the incidence of CLD according to the reduction of dexamethasone use in VLBWI. The medical records of 559 VLBWI admitted to neonatal intensive care unit at Samsung Medical Center between November 1994 and December 2002 were reviewed with a focus on the use of postnatal dexamethasone and the incidence of CLD. The use of postnatal dexamethasone has significantly decreased over the study period. Especially, the use of high-dose regimen has markedly decreased. The day when postnatal dexamethasone therapy was begun has also been significantly delayed. The incidence of CLD has significantly decreased over the same period. In conclusion, the incidence of CLD has not increased despite the decreased use of postnatal dexamethasone.

Effects of α-Phenyl-N-tert-Butyl Nitrone (PBN) on Brain Cell Membrane Function and Energy Metabolism during Transient Global Cerebral Hypoxia-Ischemia and Reoxygenation-Reperfusion in Newborn Piglets

We sought to know whether a free radical spin trap agent, α-phenyl-N-tert-butyl nitrone (PBN) influences brain cell membrane function and energy metabolism during and after transient global hypoxia-ischemia (HI) in the newborn piglets. Cerebral HI was induced by temporary complete occlusion of bilateral common carotid arteries and simultaneous breathing with 8% oxygen for 30 min, followed by release of carotid occlusion and normoxic ventilation for 1 hr (reoxygenation-reperfusion, RR). PBN (100 mg/kg) or vehicle was administered intravenously just before the induction of HI or RR. Brain cortex was harvested for the biochemical analyses at the end of HI or RR. The level of conjugated dienes significantly increased and the activity of Na+, K+-ATPase significantly decreased during HI, and they did not recover during RR. The levels of ATP and phosphocreatine (PCr) significantly decreased during HI, and recovered during RR. PBN significantly decreased the level of conjugated dienes both during HI and RR, but did not influence the activity of Na+, K+-ATPase and the levels of ATP and PCr. We demonstrated that PBN effectively reduced brain cell membrane lipid peroxidation, but did not reverse ongoing brain cell membrane dysfunction nor did restore brain cellular energy depletion, in our piglet model of global hypoxic-ischemic brain injury.