Uso da vitamina K como rastreador de eventos adversos hemorrágicos por varfarina: um estudo de caso / Use of vitamin K to track hemorrhagic adverse events caused by warfarin: a case study

The medical use of warfarin requires close monitoring because of its narrow therapeutic index. Thus, methods that enable effective monitoring to detect any adverse events (AEs) associated with this drug are necessary to improve the quality of health care. Many authors have proposed the use of triggers to search actively for possibleAEs. The aim of this study was to assess the possible use of vitamin K as a tracker of adverse bleeding events caused by warfarin in a public hospital specialized in cardiology in Rio de Janeiro. We applied the method of trigger tools (Institute for Healthcare Improvement, 2004; Rozichet al., 2003), which retrospectively analyzed the results of the use of vitamin K (phytomenadione), to screen for adverse bleeding events caused by warfarin, from October 2010 to March 2011. From an analysis of 46 medical records, 14 possible AEs were found. In 23 cases, internal bleeding was the cause of hospitalization. Despite difficulties, especially those related to poor access to data and quality of hospital records, the application of vitamin K as a trigger was found to be of great use in detecting hemorrhagic AEs associated with warfarin. This method has potential applications for monitoring the results of interventions, with a view to reducing the incidence of hemorrhagic adverse events...

O uso de varfarina requer monitoramento rigoroso devido a seu índice terapêutico estreito. Da mesma forma, a aplicação de métodos que permitam o monitoramento adequado de eventos adversos a este medicamento é necessária para que se possa contribuir com a qualidade do cuidado em saúde. O uso de marcadores para o processo de busca ativa de eventos adversos tem sido proposto por muitos autores. Neste trabalho, buscou-se avaliar o potencial de utilização do uso da vitamina K como rastreador de eventos adversos hemorrágicos causados por varfarina em um hospital público de alta complexidade em cardiologia do Rio de Janeiro. O método dos rastreadores ou trigger tools foi aplicado para análise retrospectiva da utilização da vitamina K (fitomenadiona) como rastreador de eventos adversos hemorrágicos causados por varfarina, no período de outubro de 2010 a março de 2011. Com base na análise de 46 prontuários, foram encontrados 14 possíveis eventos adversos. Em 23 casos, a hemorragia foi a causa da internação. Apesar das dificuldades, sobretudo relacionadas ao acesso às informações e à qualidade dos registros, a aplicação da vitamina K como rastreador se mostrou bastante útil na detecção de eventos adversos hemorrágicos por varfarina. A aplicação deste método como estratégia de monitoramento de eventos adversos, tem potencial para uso no acompanhamento dos resultados de intervenções visando à redução da incidência dos eventos adversos hemorrágicos...

Maternal-fetal transport of vitamin K1 and its effects on coagulation in premature infants.

We conducted a prospective study to determine (1) the maternal-fetal vitamin K1 transport in premature infants after vitamin K1 was given to the mothers antenatally and (2) the vitamin K1 effects on blood coagulation in the babies. Women in labor at less than or equal to 34 weeks of gestation were randomly selected to receive antenatal vitamin K1, 5 mg given intramuscularly (vitamin K1 group), or no vitamin K1 (control group). Eight infants, including one set of twins, were in the vitamin K1 group and six in the control group. Vitamin K1 concentrations were higher in the vitamin K1 group than in the control group (p = 0.06). Activated partial thromboplastin time was prolonged, and factor II coagulation activity and factor II antigen were proportionately decreased in cord plasma in both groups. The average ratio of factor II coagulation activity to antigen was not decreased in either group. Protein induced by vitamin K absence-II (PIVKA-II) was not detectable in any cord plasma sample in either group. These findings support previous reports that the decreased vitamin K-dependent coagulation activity in premature infants is the result of reduced synthesis of precursor proteins, rather than the result of vitamin K deficiency, and suggest that additional vitamin K1 is not likely to improve coagulation activity. Among those infants who underwent cranial ultrasonography, all four in the vitamin K1 group and one of five in the control group had mild intraventricular hemorrhage. Studies of a larger number of patients are necessary before it can be established that maternal antenatal administration of vitamin K1 results in improvement of coagulation and the prevention of intraventricular hemorrhage in premature infants.