The US Trials of Fetal Pulse Oximetry

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Dr. van der Slikke: "Here we are at the ISIS conference in Stockholm in June, 1999, and here's Dr. Gary Dildy. We met Gary in San Francisco last January, and now we want to talk to him more about fetal pulse oximetry. Gary, please tell me how the status of the randomized trial you told us about in January is at the moment."

Dr. Dildy: "The randomized trial, which was initiated 2 to 3 years ago in the United States, was concluded at the end of 1998 after enrolling approximately 1,000 women in the trial. Five hundred women received standard heart rate monitoring, and the other five hundred women received fetal heart rate monitoring plus pulse oximetry. The data has been put together into a large database, and was closed about one week ago. The data analysis was initiated earlier this week in California, and currently the data analysis is being continued because it's a rather complicated set of questions and statistical issues. We hope to have the data analysis completed in approximately one or two more weeks, so the results ought to be able to be interpreted, I would say, by July of 1999. At the present time, with the data being incomplete, it would be a little premature to try to give you an interpretation of the outcome of the trial."

Dr. van der Slikke: "That's a pity. So when do you intend to have the results there?"

Dr. Dildy: "We'll have the results together, again, next month, in July. The results will then be submitted to the U.S. Food & Drug Administration, and as I understand it, the FDA will meet in October of this year and review the research results. Pending the FDA's decision after the October meeting, we're going to know soon whether or not this device is accepted for use and distribution through the United States."

Dr. van der Slikke: "So, it's too early to give us any results, but could you tell us about the number of centers that participated, and the number of women involved?"

Dr. Dildy: "Yes, there were ultimately nine centers across the United States that were involved in this clinical trial. There were centers that were university, academic centers, and there were centers that were community referral hospitals. So we have a pretty good mix of patients that were involved and who volunteered to be subjects in the study. There were approximately 1,010 patients that were randomized, and we tried to get about 125 patients at each of the nine centers. So the numbers roughly come out to be 100-125 patients per center."

Dr. van der Slikke: "Do you think 500 patients on each side of the trial is enough to prove what you want to prove?"

Dr. Dildy: "Statistical power analyses was performed before the study was actually begun because we wanted to make sure that we had a realistic possibility of proving or determining answers to the questions that were being asked. So we do think that we have adequate power to answer those questions. There are some questions that are important which might not be able to be addressed by having a sample size of 1,000. Those are things that were considered prior to the initiation of the trial, but we feel confident we can address the majority of the questions with the number of patients that we enrolled in the study."

Dr. van der Slikke: "You told us in San Francisco, but could you repeat them? What are the major questions in this trial?"

Dr. Dildy: "The primary question or goal of the study was to determine if the addition of fetal pulse oximetry in the management of women during their labor was safe and efficacious, specifically with women who already have some abnormalities identified in their electronic fetal heart rate monitoring. Thus, the question is, can the addition of the pulse oximetry reduce the number of caesarian sections for fetal distress by a factor of 50% at the same time, while not compromising any of the outcome measures for either the mother or the baby?"

Dr. van der Slikke: "So, the answer on this question will be known within a few months. I thank you very much, Gary."

Dr. Dildy: "Thank you very much. I appreciate the chance to contribute to this program."