Use of capnography with diabetic ketoacidosis
Drug name snafu
I now have the voice of President Josiah Bartlett loaded on my computer. When I sign onto the Internet, he greets me with "Welcome, My Fellow American." When I have correspondence, the cry is "Big News! You've Got Mail!" Hearing the President-I-Wish-We-Had reminds me of the import of your correspondence and how I've been remiss in not responding to some of the more interesting letters in this column. I'll use the need to write about real-time "current events" in recent weeks as an excuse, and hope you'll indulge my tardiness.
In reference to my "Emergency Services Fairy Tale," Steven Teale wrote to remind me that not all fire services perform EMS functions. In his area of Wisconsin, there are no fire-based EMS services. He notes that only a third of all fire services in his state provide EMS services, and even fewer do patient transport.
I appreciate the rejoinder. All our opinions are biased by where we grew up in EMS, and the involvement of fire services in EMS activities certainly varies throughout the land. However, I suspect one might be able to apply the same argument contained within the "Fairy Tale" to the interactions of pure fire services as well.
In Florida, virtually all fire services have assumed at least BLS first response capabilities. We can debate the reasons for this. I'd like to think it's all a result of a genuine desire to serve the community. I fear that some of it fulfills the political need for an overfunded fire service to show a degree of activity in an era of effective fire prevention. While I believe that the vast majority of public servants are indeed motivated to serve, I've unfortunately started to "read" the rationale behind public service and governmental statements the same way I advise families of patients with head injuries. We always hope for the best, but we expect the worst.
One amusing note on how my work has come back to find me. I've always thought that one of the beauties of this column was the ability to whine to an international audience without the political correctness required of a medical director. So I was surprised last weekend when a paramedic told me that I had made the local paper. Turns out that a local city official had gotten hold of my "Emergency Services Fairy Tale" article and objected to its content on the public record (the paper didn't actually print the column, so all I can think is that its readers were totally in the dark). This, of course, occurred the very night that the same group passed a resolution advocating participation in a closest-unit response system; and a few days later, the city manager proposed a regional fire service administration. Of course, there's no double standard there.
(By the way, I want to extend a public pat on the back to my editors at jems.com for a splendid job of "tightening up" the piece, even if they did take out the best jokes.)
Use of capnography with diabetic ketoacidosis
In addition to my weekly excursions on the World Wide Web, I also contribute to the Case of the Month column in the magazine version of JEMS. I recently authored a case description of a patient in ketoacidosis from gestational diabetes. This report prompted several readers to ask about the use of waveform or digital capnography in diabetic ketoacidosis.
There's not a lot of literature on the use of capnography in conditions characterized by a metabolic acidosis. My suspicion is that what capnography would show in a metabolic acidosis (uncontrolled gestational diabetes results in DKA, just as Type I DM does) depends on how early the illness is "caught." The buildup of acids (free hydrogen ions, actually) in the blood is mediated by the bicarbonate buffer system. As you may recall from school, in metabolic acidosis, bicarbonate takes acidic hydrogen ions out of circulation by binding them. The bicarbonate molecule then breaks down into CO2and water.
Hyperventilation is designed to blow off excess CO2. In the early stages of the metabolic acidosis, hyperventilation usually does it's job, and CO2 levels would be expected to be low. However, as the acidosis progresses, CO2 production increases, and the capnographer will then register an elevated value. There's one tiny catch to this. In theory, after all the bicarbonate in the system is "used up" trying to respond to free hydrogen ions (there may be no substrate left to produce more CO2), and end-tidal CO2 may fall just prior to the end. In real life, I don't think that would ever happen. If you've really got no bicarbonate left at all, you're pretty much gone, and you've most likely gone into shock and cardiac arrest. At that point, the paramedic has more to worry about than capnography, and your end-tidal CO2 is likely to be elevated due to a superimposed respiratory acidosis.
Two quick follow-ups from my effort on drug interactions in EMS. Norm Rynning writes to tell me of a patient who took a Claritin-D tablet in the morning and had three glasses of wine later that afternoon. By early evening, she was unconscious with a respiratory rate of 4, and was able to tolerate an oral airway. (As the all-powerful Seer of Prehospital Care, I know what you're thinking. These were normal size glasses, not the yard-long flutes used by patients who say they only had two beers and then produce an alcohol level of 378. And it really was red wine, not Everclear with a hint of food coloring or lipstick stains). The patient slowly regained conciousness over the next several hours, with no ill effects reported.
The active ingredients in Claritin-D are pseudoephedrine (a sympathomimetic) and loratadine (an antihistamine). Signs of sympathomimetic toxicity include tachycardia, tachypnea, palpitations, and hypertension, so this reaction would not seem to be related to the pseudoephedrine component of the drug. Antihistamines such as loratadine may also cause tachycardia, but often produce bradycardia in association with sedation. The sedation factor is why all antihistamines are labeled with a warning to use caution while driving or performing other tasks that require mental alertness. I suspect this case represents an exaggerated interaction between the antihistamine component of the Claritin and the patient's alcohol intake. The case is a valuable reminder that even everyday "benign" drugs can have significant effects when combined with alcohol.
Another correspondent asks if the practice of smoking marijuana "wet" (after soaking in formaldehyde) would cause disulfiram (Antabuse) reactions. He notes that symptoms seen in patients who've done this combination, such as combativeness, tachycardia and vomiting, are similar to what one would see with an Antabuse reaction. This is a great observation, and one would expect the inhalation of formaldehyde (first cousin to acetaldehyde, the breakdown product of ethanol that produces the Antabuse reaction) to provoke a similar clinical picture. Interestingly, I don't think that the inhalation of formaldehyde by a patient on Antabuse would provoke an exaggerated reaction, as the effect of disulfiram depends on the presence of ethanol as a substrate. If there's no alcohol on board, there's nothing for the Antabuse to work on. For the record, I had not yet heard of this form of drug use. Maybe I need to get out more. Thanks for the tip.
In regard to the article on my long-lost cousin Tred, Bryan Mayo (who may have a clinic named after him) asks about the rationale of obtaining orthostatic vital signs if the Trendelenburg position has no merit. He indicates (rightly so) that the utility of orthostatics as a measure of volume status implies that a change in body position can lead to a rise in blood pressure, validating the use of the head-down incline.
It's important to recognize that while the Trendelenburg position and the assessment of orthostatic vital signs both involve the placement of the body in space, the Trendelenburg position represents an extreme, unnatural posture. Assessment of orthostatics is simply a diagnostic maneuver that infers if the body exhibits an abnormal or exaggerated response to a change in position. The positions used include lying, sitting, and standing, and not supine in the 45-degree head down posture used in the Trendelenburg position. Of the three positions used in the determination of orthostatic vital signs, the most benign is lying supine, and indeed the classic orthostatic changes associated with volume depletion reveals the blood pressure to be higher in this posture than while sitting or standing.
Naturally, we can obtain this position (and maximize our own blood pressures) by simply lying down. However, we cannot naturally place ourselves in the Trendelenburg position (feel free to try). It's not how the body was designed to work, and the multiple side effects and adverse consequences associated with its use betray our evolutionay heritage. I do believe that a "happy medium" may be the use of the patient supine, legs elevated, head and body neutral position (taught in most first aid courses), which possibly promotes central venous return without invoking the problems of the "true" Trendelenburg alignment. I don't know if this procedure is particularly helpful, but it surely does no great harm (assuming spinal integrity is intact).
A few weeks ago, I ran an article on pain control in EMS. I was fortunate to receive a lot of positive feedback on that article. Since then, I've run across a few additional pieces of information that may be of interest. One comes from the latest edition of a small book titled Cope's Early Diagnosis of the Acute Abdomen. Rumor held that this book, which remains a masterwork of history-taking and physical examination, was largely responsible for the surgical doctrine opposing the use of pain medications before surgical evaluation. As I've now discovered, early editions of the text indeed advised against the use of pain medications before surgical evaluation, in the fear that the effect of narcotics would obscure the physical findings. (At the time, 30 mg of IM morphine was the pain therapy of choice. In a contemporary context, the concern seems well-founded.) I'm pleased to report that modern editions of this work note that this concern is likely erroneous, and that making patients wait for hours before getting pain relief is a "cruel practice to be condemned." Nonetheless, considerable opposition to the use of analgesia before surgical evaluation persists. A 1999 article by Graber and colleagues in the American Journal of Emergency Medicine noted that in a survey of general surgeons, 67% felt that the use of pain medication interfered with diagnostic accuracy, and 53% felt that narcotic use stopped a patient from signing a valid consent for operation. The overlap of these views meant that in their sample, only 7% of patients with acute abdominal pain received analgesia before being seen by a surgeon.
The most interesting item about the whole pain medication debate has been the fact that Cope's original argument against analgesia, which was limited to "hidden" causes of abdominal pain, has been extended in an extremely inconsistent fashion to more obvious causes of pain. Somehow we've been neglecting pain management in patients with grossly obvious fractures or significant soft tissue trauma, conditions where the diagnosis is rarely in doubt. I think it's in these patients that aggressive prehospital analgesia can exert its most beneficial effect.
(Editor's note: For an in-depth discussion of pain control, check out "Pain & Comfort," June 2003 JEMS.)
Drug name snafu
Many readers have written to remind me that I recently assigned the wrong trade name to the drug midazolam. Midazolam is known as Versed; Ativan is the trade name for lorazepam. I apologize for the oversight. (Although if I can parlay this error into a book deal like Jayson Blair, it might happen more often.)
A quick update on the malpractice crisis and its impact on EMS. As I write this, our trauma surgeons here in Daytona continue to play hardball in their threat to terminate trauma call on June 1. In addition, the radiologists intend to stop doing mammograms, citing high insurance premiums and medicolegal risks (they've worked out a deal to continue until August).
After quietly noting the impending crash of our Trauma Center, our Sunday paper trumpeted the claims of a malpractice attorney that the malpractice crisis is not the poor doctors' fault, but that of the insurance companies (translated as "Don't protect the doctors like a remora, I need them for my sustenance and someday a doctor might have to take care of me, and might remember who I am"). The barrister also thinks that a cap on non-economic damages might be unconstitutional, because if someone has no income, their recovery would be limited to the non-economic maximum of $250,000.
It seems to me that if it's unconstitutional to limit someone's damages due to their baseline financial status, then all other activities we base on financial status (such as the extension of credit) must be unconstitutional as well. Even from an abstract view, I don't see a problem. Society places values on life all the time (we don't admit it, but we do). The dollar value of life is manifested in the way our life and health insurance plans are made, in the premiums we pay and in the way that government allocates resources and makes cost/benefit policy decisions. The fact that physicians do, and will continue to, provide acute care for anyone regardless of financial status grants medicine an ethical "high road" not shared by the remainder of society. If you can't pay, you still get free care; and even if something should go terribly wrong, there's a potential for compensation despite that fact that you've contributed nothing toward the provision of that service. It's not too bad of a tradeoff.
Meanwhile, the paper notes that the local trauma surgeons are actually covered by the hospital's sovereign immunity (the extent of that coverage is debated by the surgical group), but the hospital spokesman says that sovereign immunity really only "slows down" an attorney. The paper also did the medical community the favor of listing the most expensive local medical malpractice judgments, complete with names of plaintiffs and defendants.
In Tallahassee, the Florida Legislature met again in special session, passed a budget behind all-but-closed doors, convinced the governor to kill the Everglades and got out of town. The malpractice issue remains in limbo. And last weekend, we got our first calls from Jacksonville, where the majority of surgeons are on strike, and no one was available to treat a patient with an abdominal abscess. By the time you read this, it will be early June, and Zero Hour will have come and gone. I'll let you know how it goes.Finally, I've been asked on occasion if I'm available to speak at conferences. I'm always happy to do so. For the record, I'll also do weddings and bar mitzvahs. If I can be of service to your group, please feel free to contact me at AMDEMS@aol.com. And I'm always looking for new topics of interest to you, so if there's an issue you'd like me to discuss, let me know at the same address. Thanks!