24 As a result, the Dutch prophylactic dose was increased from 25 μg daily to 150 μg daily for 3 months after birth. 23 In a national surveillance study, the Netherlands described a rate of late-onset VKDB of 3.2 per 100 000 live births, based on an oral regimen of an initial dose of 1 mg of vitamin K followed by a daily dose of 25 μg. A 6-year follow-up surveillance study in Switzerland demonstrated a significantly lower rate of late VKDB of 0.87 per 100 000, with the main risk factors being parental refusal of any prophylaxis and undiagnosed cholestasis. 22 This schedule included 3 oral doses of 2 mg of vitamin K given at birth, day 4, and week 4 of life. In a Swiss study using 2 oral doses of 2 mg of vitamin K on day 1 and day 4, late-onset VKDB was rare but still occurred, with an incidence of 3.79 per 100 000, and a 3-dose schedule was subsequently recommended. 21 Failure to prevent late-onset VKDB continues to be an issue with oral prophylaxis, despite the use of multiple-dose oral schedules. The 2003 AAP statement cited multiple reports of late-occurring VKDB in countries that established policies of oral prophylaxis of infants, with a single oral dose of vitamin K after birth shown to be less effective than a parenteral dose. 17 Whereas oral vitamin K appears to be effective in preventing classic VKDB, 18– 20 there are concerns about its ability to prevent late-onset VKDB.
In 2003, the AAP reaffirmed the use of vitamin K to prevent VKDB and recommended that all newborn infants receive a single IM dose of 0.5 to 1.0 mg of vitamin K. Vitamin K Prophylaxis of the Newborn Infant 13– 16 The high incidence of mortality and morbidity, along with its virtual elimination with prophylactic vitamin K, has made it a focus of public health interventions around the world. All of these studies have shown significant reductions in late-onset VKDB in the population. There have been no randomized trials evaluating the efficacy of early postnatal intramuscular vitamin K in eliminating late VKDB 12 however, there are several large national surveillance studies that have examined rates of late VKDB since the introduction of vitamin K prophylaxis in Japan, Germany, Great Britain, and Thailand. Late-onset VKDB most commonly presents with evidence of intracranial bleeding in 30% to 60% of cases.
It may also be associated with liver dysfunction secondary to neonatal hepatitis, bile duct atresia, 11 or intestinal malabsorption.
10 Late-onset VKDB is usually associated with exclusively breastfed infants who did not receive vitamin K prophylaxis at birth. Late-onset VKDB occurs between 1 week and 6 months of age, with a peak incidence between 2 and 8 weeks.
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