Differential Diagnoses

[Jonas]

Differential Diagnoses

I’m an old orthopaedic technician/paramedic. I worked summer jobs in hospitals since my sophomore year in high school, then all through college. While I was in no way interested in becoming a medical doctor, I got my paramedics license in 1977 more as a side interest than anything else. In 1982 there was a shortage of EMTs in the US Coast Guard so I became a “weekend warrior” for what I thought was three years. I went on to other assignments, finally hanging up my boots in 1996.

Emergency medicine in the Coast Guard was practiced quite differently from what paramedics and EMTs did in the civilian world. USCG EMTs work alone – no partners. We also responded by boat so our response times were not 5 to 10 minutes like most civilian ambulance services, but rather 45 minutes to over an hour. Our transport times were equally long, unless we whistled up a helicopter from a Coast Guard Air Station and airlifted the patient off our deck.

“Differential diagnoses” refers to a mental list of all the possible things that could be wrong with the patient, and usually this list is running in the EMT’s mind long before he/she gets to the patient. As you examine your patient, you eliminate some items on your list, add others, and hopefully arrive at the correct answers and apply proper treatments as necessary.

For instance, I was walking up the CG Station steps early one Saturday morning, when two boys on bicycles came up to me and said “there’s a woman fallen down on the pier out by the pier-head light”. The pier was about one half mile long, and I know we could get there fastest by boat so I went into the station, told the OD to scramble the duty boat crew, grabbed a mustang suit and the med gear, and ran for the 41’ UTB. I jumped on and away we went, lights and siren, down the channel.

So what were the “differential diagnoses” when we pulled away from the station? Pretty much nothing could be ruled out. “Woman down” could be a fall, a faint, a stroke, an aortic aneurysm, insulin shock, and on and on and on. Once I got on the scene, I could see that the woman was conscious and coherent. Rule out insulin shock. No muscle droop in the face and clear speech. Rule out TIA or CVA (or at least move them to the bottom of my list). Get vital signs – blood pressure, pulse, respiration. OK, didn’t look like an MI. Color good, not cyanotic, not short of breath. Listen to her lungs. Lungs clear. Did she lose consciousness? She didn’t know! Epilepsy? Petite mal? Grand mal? No physical sign of head injury, swelling, contusion, or abrasion. What did she have for breakfast? Low blood sugar? What medications was she on? And so on and so on, until I knew enough to treat her sore knee and pass her on to the civilian ambulance crew that showed up fifteen minutes later. Working diagnosis (and my best guess)? Unexplained syncope and bruised left knee. Possible tear in the medial and/or lateral meniscus.

OK, so how does all this apply to a survival scenario? Use the same mental procedures to evaluate the scenario as I did to evaluate my patient. Initially you have a power failure. Cause unknown. What are the possible causes? Is it only on our block? Half the town? Half the county? Look out the windows and observe. What are the best guesses for power restoration? In what time frame? Cell phones work? No? How about the land-line phone? TV broadcasts? No? How about commercial radio broadcasts? Where are you located? Big city? Small town? Farm out in the boondocks? How many people are with you? Any physical limitations there? Someone on medications? What meds? If you’re at your own home, you know what’s in the pantry and how long you can feed any guests. If you’re visiting someone else, you don’t know what (if any) food, water, or anything else that they may have. So what do you do to best assure the survival of your family and yourself? Leave? Stay? Head to the local pub across the street?

The point is, all survival scenarios, both real and hypothetical, can be approached in the same manner as used in establishing a diagnosis of a medical patient. Start out with the premise that every possibility is in play, and work to eliminate each possibility (or as many as possible). Make your survival decisions based on logic, provable facts, or at the very least, the highest probability. Write things down, so there’s no chance of getting times and the order of events wrong. Trusting to blind dumb luck is NOT a good survival plan!