Daniel Katz, MD, an Assistant Professor of Anesthesiology who does Obstetric Anesthesiology talks about the risk of blood loss during child birth and how doctors are using new technology to save lives.
Interview conducted by Ivanhoe Broadcast News in April 2018.
I wanted to ask you just briefly to run through some of the complications and some of the risk factors that could cause a woman to lose blood during childbirth?
Dr. Katz: Sure. It will depend on the type of delivery that they’re coming for, either coming for a normal labor and delivery or for caesarian section. In general, as medical co-morbidities and age increase, the risk of having a hemorrhage will also increase. Anything that will distend the uterus above and beyond what is a normal pregnancy will also increase the risk of bleeding. For example, patients who have large amounts of amniotic fluid, patients who have multiple gestations like twins or triplets. And obviously if anyone has had a prior history of hemorrhage that is also a risk factor.
How common is it?
Dr. Katz: About three percent of mothers are going to experience some type of obstetric hemorrhage around the time of labor and delivery. And while three percent may seem like a small number, considering for example that we do eight thousand deliveries at Mt. Sinai alone, it winds up being quite a number of mothers. And obstetric hemorrhage is one of the leading causes of maternal mortality in the United States. Depending on how you slice the numbers it’s one, two or three when you talk about worldwide versus New York State versus other population distributions.
So right now how is it monitored in the OR?
Dr. Katz: The traditional way of monitoring blood loss is done by visual inspection. Meaning that we essentially look at the saturated pads, we look at the operative field and we make an estimation with our best guess what the blood loss is.
Usually with a lot of experience I would imagine that’s pretty accurate?
Dr. Katz: It’s really not the greatest. I can say beyond personal experience there’s actually been lots of literature examining how good we are at estimating blood loss and we’re really not as good as we would like to think. Our eyes are excellent at doing lots of things like contrasting colors, detecting motion, but estimating volume is really challenging. We tend to overestimate small volumes and under estimate large volumes. That is often the critical piece when you’re dealing with a maternal hemorrhage.
So with that in mind, what could be the concern?
Dr. Katz: The concern is that you either act too aggressively when you don’t necessarily need to. Like performing unnecessary procedures or giving unnecessary medications or blood transfusions. The more dangerous one is that you don’t realize that you’ve lost a lot more blood than you have and then you under treat a severe or very severe hemorrhage.
Can you talk to me a little bit about the current technology that is designed to help doctors monitor how much blood loss there is?
Dr. Katz: Sure. It’s essentially another set of eyes or I guess it’s a digital eye. What it will do is actually quantify how much blood is being lost. And it does it through a couple of different ways. The first way is through photometric analysis, so essentially it will take pictures of surgical sponges and canisters and actually measure how much hemoglobin is on them. Knowing the hematocrit of the patient or the hemoglobin concentration of the patient can actually tell us the volume of blood on that sponge. Something like that is really critical in labor and delivery because our volumes are contaminated with things like amniotic fluid and surgical irrigation fluid. For example, you can have a suction canister that has three liters of fluid in it and has a little bit of red in it and you really don’t have any idea how much of that canister is actually blood. And the same thing goes with surgical sponges they all get saturated and this tells you exactly how much blood is on that surgical sponge.
How quick and how easy is it to use?
Dr. Katz: It’s very easy, the canister scans themselves are done via QR code for calibration and a quick picture that takes one or two seconds.. The surgical sponges are done in real time. So they’ll take the sponge off the field and the scrub tech or the nurse will then unfold the sponge, put it in front of the camera, it takes a picture and within a second or two you have how much blood is on that sponge. And then the system coordinates those two values [sponge and canister]together to give you a cumulative tally as bleeding goes on.
Could you walk through what the process would be to be to get that amount?
Dr. Katz: What would happen is the obstetrician who is performing the surgery or the delivery would pass off a sponge to the scrub tech who would then pass it off the table to make sure the count is correct. Then they’ll unfurl the sponge so it’s almost like a perfect square or rectangle. You then hold it up to the 3-D camera in front of the machine. The machine takes a picture, makes a noise to let you know that it’s captured. Then it runs an algorithm that is on the machine itselfand that gives you an amount of hemoglobin, an amount of blood.
At what point do doctors or the nurses know that there may be a problem? Is there a threshold?
Dr. Katz: There are thresholds that are quoted in the literature for what actually constitutes a maternal hemorrhage. Currently it’s around 600 ml’s of blood loss for a vaginal delivery and around 1,000 ml’s of blood loss for caesarean section. But every institution uses its own guidelines. And the great thing about this technology is we can gain a level of specificity and sensitivity that we never really could. It would be impossible for us to determine with our eyes the difference between twelve hundred and fourteen hundred ml’s of blood loss but this machine can do that.
Is Mt Sinai currently using it or is it still in trial?
Dr. Katz: We’re currently usingit. In fact, we were the first institution in the entire country that is using quantitative blood loss with this technology for all deliveries; both vaginal and cesarean.
Can you speak about how well this is working, are there cases where there’s more blood loss than doctors anticipated?
Dr. Katz: There are. There’s always cases where we are surprised by the numbers that we’re getting back from the system and we’ve sort of changed our management. There’s always a lead in period when we introduce new technology. People first have to get familiar with it, then they have to believe in it, and then they have to change their practice around using the technology. And that’s sort of where we are, where people are realizing how useful the information is and actually starting to change their practice. So for example, we’ve noticed that people are using this number to guide their transfusion strategies in the operating room as well as to dictate how quickly they escalate things like advanced uterotonic management and other aspects of managing a hemorrhage in a more aggressive manner.
If you get that instantaneous read out and a patient has lost too much blood what is the next step?
Dr. Katz: Continuing to manage the bleeding is of course a first concern. We’ll often do a mini huddle once we’ve reached a certain threshold to say to everyone in the room, okay we’ve now reached a stage two of hemorrhage, we’ve done X, Y, and Z thus far what do we have left to do or what else can we do to help manage the patient.
And where does this technology go from there?
Dr. Katz: Well the application of the technology goes actually outside of the operating room and the delivery suite. We are also doing accumulative assessments of quantitative blood loss during the first twenty four hours for our patients, especially if they have experienced a hemorrhage. So for example, we’ll get a number of how much blood was lost during the time of delivery and then subsequently every time they either have a soaked pad or experience a bleeding outside the operating room that number gets quantified and then gets tallied with what was lost in the delivery. Such that by the time we’ve reached the time for discharge we can actually tell the patients with very high certainty whether or not they’ve experienced a hemorrhage. And that way they can know for their own history the next time they come back that they were at risk because they’ve had it before once.
Is there anything I didn’t ask you that you want to make sure that people know about the technology?
Dr. Katz: One of the most critical parts about this technology is not necessarily the number that you get though quantification should be all about the numbers. But it’s about the system that you put around it. What’s really given us a lot of success with this technology is that we’ve built a system of algorithms and decision making tools to really implement the information that we’re getting from the system. If you don’t use the information to change the way you’re going to practice then the utility of the system isn’t going to be that high.
END OF INTERVIEW
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