Q&A with Paul Pepe, MD, MPH, MACP, FACEP, FCCM

   This month, we speak to acclaimed emergency physician Paul Pepe, MD, MPH, MACP, FACEP, FCCM, chair of emergency medicine at the University of Texas Southwestern Medical Center and the Parkland Health and Hospital System, and medical director for Dallas EMS and the Dallas metro-area BioTel EMS system. Dr. Pepe delivered three presentations at the 2010 EMS World EXPO, including, with colleague Jane Wigginton, the keynote address. Here we discuss some of the specifics of his presentations. 

   Your keynote, "Sex, Drugs and R&R (Reanimation & Resuscitation)," concerns the role of sex hormones in cardiac arrest outcomes. What is that role?

   With cardiac arrest, it can appear on the surface that men do better, because they present more often with ventricular fibrillation. But when you break it down by presenting ECG, women actually have better outcomes. Initially we didn't think hormones were the reason, because the average age of women who have cardiac arrest is around 68.

   So we conducted a prospective study in Dallas over 10 years to try to see if there were any differences between men and women, and particularly look at those under age 50 vs. older than 50. We found that the women had much better outcomes, especially in cases where they had more ischemic insult--particularly in cases of asystole and pulseless electrical activity, the women had much better outcomes relative to the men. And the cohort of women under 50 was actually accountable for most of the differences.

   So there's this observation that women of child-bearing age do better, and we started thinking that indeed it is hormones. However, this conclusion was inferential--we didn't actually measure the hormone levels, but it sure sounded compelling. It turns out, in fact, that in the experimental literature, there are literally dozens and dozens of studies in which estrogen--also progesterone, but particularly estrogen--has been shown to be an extremely protective substance. In various animal experiments, it's not only protective, but it's actually therapeutic as well, meaning you could give a dose of it to a male or a female after an injury, and they would have better outcomes. It doesn't matter if it was a stroke or a head injury or cardiac arrest or something else; it turns out estrogen provides a substantive advantage in outcomes.

   So now we're conducting clinical trials. Accordingly, we're going to talk about all that during the keynote session, but also give some background information and where we're going with it. It's really about how we stumbled upon something by a simple observation that anybody could have made, but we also pursued it with subsequent observation and research, and now it's leading to a whole new area of investigation and clinical care called resuscitative endocrinology.

   Don't be surprised if five years from now, administering sex hormones becomes the standard of care for critically ill and injured patients.

   You're also talking about "anachronistic catastrophes" and issues of disaster medicine. What's the gist of that?

   The simple answer is that the world has changed from 50 years ago, and what might have been a lesser disaster then can, in this day and age, become one of global importance.

   If a small seaside village in Thailand were hit by a tsunami 50 years ago, we may not even have heard about it. Today it's beamed into our living rooms, because it's no longer a seaside village of 5,000 inhabitants, but now a destination resort for a million people from 30 countries, not to mention all the hotels and chains and businesses wrapped into that.

   We've also become a larger target: Billions more live on the planet, many in high-risk locations. We're also living longer. Although technology gives us some advantages, it also presents us with bigger risk. We've become more dependent on others for food and energy sources, and thus more vulnerable. So the point is we're a bigger target, and there are more things to be afraid of. We used to think all disasters were local. Well, they're local, but they're also global now, and their impact is getting worse.

   Your final piece concerns the perils of rescue breathing. What perils do you mean?

   When you and I take a breath, our diaphragms are round, dome-shaped muscles that, when they contract, pull down, and that creates a suction. It sucks air into the chest, but it also sucks blood back into the heart, and that's important because, particularly when you're exercising, you have to pump more blood out. However, when we're giving a positive-pressure breath for somebody, we're actually pushing the lungs open and in turn transiently inhibiting blood flow back into the heart. So if you get somebody in a low-flow state, such as cardiac arrest or severe trauma with bleeding, then there's very little blood flow going in already, and overzealous positive-pressure ventilation could actually be lethal.

   So what this is all about is that ventilation should match perfusion. If you're in a very low-flow state, you don't need to ventilate much. That's particularly true in trauma, and I'll go into that in great detail, along with some other exciting new concepts.