Apparently breath analysis is becoming a hot research topic. By studying the contents of a person's breath, multiple medical maladies can be diagnosed. For instance, nitric oxide levels in the breath are elevated when the airways are inflamed thus signaling an asthma attack. Irritable bowel syndrome sufferers may show increased hydrogen levels due to bacterial overgrowth. The possibility of making meaningful diagnoses without expensive invasive procedures or painful blood draws certainly merits more research.
However we anesthesiologists are already experts at evaluating a patient simply from the odor of his breath. As masters of the airway, we are frequently up close and personal with a patient's exhalations. Thus after years of experience I can tell you what somebody's breath reveals about their health.
You tell me you haven't smoked in six months just so you can get that transplant? Then why is it that as soon as I open up your airway during direct laryngoscopy, I feel like an ashtray has been emptied into my nostrils? I may not be able to tell whether you've been lighting up with Marlboros or Winstons but I know you haven't quit smoking like you claimed to have done. Case cancelled.
How about your claim that you haven't used marijuana and are now living a clean and sober lifestyle. Again one peek down your airway and my face is assaulted by the atmosphere from a Grateful Dead concert. You just couldn't make it down for your surgery without a quick stop at the local "medical' marijuana shop? Don't tell me it's to alleviate postop nausea either.
Then there is the trauma patient brought emergently to the operating room after driving into a tree. What a freaking mess. I do a quick rapid sequence intubation to get the case going. As I do so, my nose is confronted by the uniquely rancid odor of blood, alcohol, and partially digested food emanating from the mouth. As soon as I drop down an orogastric tube into the stomach, I am proven right. Out comes hundreds of cc's of the patient's last pitcher of beer and what looks like a pureed mixture of nachos and pepperoni pizza.
Yup we anesthesiologists have developed quite an acute awareness of our patients and their breaths. We don't need any special sniffing equipment either to tell us what we already know from years of experience. And we even do it for free.