Noninvasive blood pressures

When I am attending, I use non-invasive blood pressure (NIBP) monitoring all the time.  I have my own adult automatic cuff that I bring to work.  I find it to be practical on long transports and on patients where I need serial blood pressures.

Dr Pierre Potain's sphygmomanometer, circa 1870
Credit Wellcome images, via Wikimedia Commons

I find, though, that most other medics despise automated blood pressures.  I am most often told that the blood pressures of NIBP cuffs are unfailingly incorrect.  I have always thought this was both funny and the perfect description of a paramedic’s mindset: "All of the rest of medical practice is wrong, except for how I do it."  Think about it – NIBP readings are used in doctors’ offices, emergency departments, operating rooms, and hospitals all over the world.  Do you think that nobody checked to see if these things worked? 

To me, the biggest benefit to using NIBP is that it frees me up to undertake other tasks.  If there are no other tasks, it frees up my brain to think about the call.  Contemplating the call (what else could be going on, what I may be missing, what else I could be doing, and those types of things) is the most significant task on a call. 

Some of the best overview information comes from two nursing documents.  The first was a 2002 article in the journal Critical Care Nurse.¹ Apparently nurses had the same concerns that medics continue to have: “Despite the widespread use of automated blood pressure monitors, clinicians continue to deliberate over the accuracy and reliability of automated NIBP devices compared to other methods of blood pressure determination.”  The article cites nine studies that support NIBP accuracy, within 5mmHg of direct arterial pressure measurements.  The article states, however, that there can be occasional random NIBP pressures that vary from the arterial pressure by more than 30mmHg and cautions clinicians against making treatment decisions off of a single NIBP reading.

The Emergency Nurses Association wrote a clinical practice guideline regarding noninvasive blood pressure measurement in 2012.² This document works through pertinent research to reach three main recommendations: Compare NIBP readings to auscultated BPs, use the right sized cuff, and follow manufacturers’ guidelines.  More specifically, they find that NIBP measurement is suitable for adult patients, patients with trauma and shock, and children.  Evidence for NIBP use is weaker in the case of patients with chronic hypertension, atrial fibrillation, pregnancy, and alternative cuff sites. 

So if you are finding that the auto cuff is returning readings that are grossly different from your auscultated readings on a consistent basis, the cuff may not be the problem.  But, like any tool, automated BP cuffs have limitations.  They are usually a bit slower than I am.  They can be confused by arm movement or flexing against the inflated cuff.  Reported variations between auscultated blood pressures and automated blood pressures range from +5.4 to -11.2 mmHg in systolic blood pressures.  You need the right cuff for the patient.  They can occasionally fire off a wildly wrong reading.  Finally, I have a suspicion that NIBP readings have more variation at the extremes of systolic pressures. 

Auscultated blood pressures have limitations, as well.  Blood pressures take two hands and one brain.  No studies have established the range of variation between measured arterial pressure and the auscultated pressure reported by the new firefighter who inflated the cuff four times and has a look on his face like he is translating calculus to French in his head.  Like with NIBPs, you need the right cuff to fit the patient.  Finally, auscultated blood pressures have no automatic setting to result in a blood pressure reading every three minutes (or 10 minutes or 30 minutes…).

Thus, like with any tool, procedure, or medication, I need to balance the positives and negatives of NIBP readings against the pros and cons of manual blood pressures.  When I am tending to most patients, I check a manual blood pressure first.  After all, it is pretty quick and simple in most cases.  If I have a patient that is likely to need another blood pressure reading, I use the NIBP cuff.  Because arm movement can screw with the blood pressure reading, the patient needs to be able to hold still and not flex against the cuff.  So they need to be unresponsive or able to follow directions.  The NIBP cuff needs to give a reading that is in the same ballpark as what I got with the manual cuff.  If all that is true, I can set up the cycle time for something appropriate and get back to other work.

Don’t completely ignore the NIBP cuff.  It can be a pretty helpful tool.

1. Dobbin KR. Noninvasive blood pressure monitoring. Crit Care Nurse 2002;22(2): 123-4.

2. Emergency Nurses Association 2012 Resources Development Committee. Clinical Practice Guideline: Non-invasive blood pressure measurement with automated devices. December 2012.  Accessed January 15, 2015 http://www.ena.org/practice-research/research/CPG/Documents/NIBPMCPG.pdf

Emergency Calls

A while back, I was called to a library for an employee who was having chest pain.  I arrived to find a 55-year-old female librarian in the back office.  She looked generally okay, and one of her coworkers was on a cell phone.  “Oh, good. They’re here,” she said.

I assumed she was talking to the calltakers at the communications center, so I asked her to hang up the phone.  The 911 calltakers’ calls are recorded, after all, plus they have other calls to take.  “Oh, no.  This is her husband.  Tell him where you are taking her,” she said as she tried to hand me the phone.

Why do people feel the need to do that?  Why do they want to call the patient’s loved ones and tell them nothing?  They know nothing!  What is that urge?  I don’t get it.  (Obviously.)  At that point in a call I usually don’t even know if the patient is going to the hospital, let alone which one.  Give me a minute. 

I can think of a bunch of reasons to not call family members.  For the most part, the patient can do that when my physical exam and clinical history have been done.  Most calls have a break point where I have all the information I need, but we aren’t at the hospital yet.  If that break point never occurs, the hospital can take care of calling people the patient knows.  The worst part of it is that people expect information before I know anything. Finally, I am the professional expert that you called to help you during this emergency situation.  It is unlikely that you called 911 so that I would arrive and talk on the phone with the librarian’s husband.  I need to do my paramedic thing.

But there are calls, on rare occasions, in which I need to talk to the family on the phone.  For example, once I was working at the airport when the report of a sick female on a diverted flight came in.  A diverted flight is one that isn’t supposed to be landing here; it was supposed to be passing over from Point A to Point B.  My airport is Point A-and-a-half.  Diverting a flight is a really big deal.  The airport has to make up all of the missed connections on the flight, pay landing fees, refuel, and so on.  So if a flight crew decides to divert, something on board really scared them.

In any case, this diverted flight involved a 17-year-old who was flying alone.  A bystander on the plane explained that she had chest pain and shortness of breath, but kept getting worse and worse.  Nobody on board could register a blood pressure, but they gave her two nitroglycerin tablets anyway.  Now the girl was having a seizure.

When I met her, she was experiencing a raging anxiety attack.  Apparently the carpopedal spasms were misidentified as a seizure.  She had a respiratory rate above 80 per minute with clear breath sounds.  She was normotensive (I had no problem with hearing the BP) and a little tachy.  She had a room air sat of 100% and an end-tidal CO2 of 5mmHg.  Rock on, little rocker.  Hyperventilation is a bear.

Anyway, I worked through the call while I waited on the transport ambulance.  The patient couldn’t talk to me, though.  She could tell me that she couldn’t talk, but that was all she would say.  I tried to point out that telling me her medical conditions took just as much talking as telling me that she can’t talk, but to no avail.  I was still vaguely considering the risk of PE, so I wanted to know about birth control use, smoking, previous anxiety issues, and such.

With the girl’s permission, I got into her bag, found an iPhone, and called her emergency contact.  It was her mom, who was supposed to be picking her up at another airport in a different time zone.  I explained what was going on, got a medical history, medication list, and such, and let her know that her daughter would be off to the hospital.  I gave her information about the hospital like contact numbers and generally explained everything.  Mom was nice.

In that case, calling the emergency contact was helpful.  But I did it for a reason – I needed information.  But it is pretty rare to find someone who is unable to clearly communicate, when I need information, and they have a cell phone.  I realized that not a lot of medics know how to get into the ICE (in case of emergency) stuff on smartphones.

For iPhones:

Slide to unlock.  It will ask for a code.  Just tap ‘Emergency’ on the bottom left of the screen.

You are at an emergency call screen.  Tap ‘Medical ID’ at the bottom left.

Assuming the iPhone user has their phone set up, it shows the owner’s name and birthday, medical conditions, allergies, and an emergency contact.

Tap the emergency contact’s phone number and the phone will call it, locked or not.

For Android:

Android owners can set up emergency contacts as part of the phone’s owner information. 

Alternatively, some Android owners take a picture of emergency information and set it as their lock screen photo.

Finally, there are third party apps that can function similarly to the iPhone system.

In the end, it is hard to tell which system your patient used (if any). 

I have no idea how to get to the emergency contacts on Motorola's DynaTAC 8000x.  Sorry.
(Photo Credit Redrum0486 via Wikimedia Commons)

I hope this helps.  It isn’t often that we need to access a phone, but those situations do arise.  As far as I am concerned, letting emergency contacts know that you are taking an adult patient to the hospital is unnecessary and may violate confidentiality.*  I avoid that.  But sometimes, rarely, whatever medical information you can get is a big help to the performance of your job. 

*Conversation to avoid: “Who owns this phone?  Oh, your husband, huh?  Well, we found him without clothes, wearing an inflatable Viking helmet, passed out in a puddle of urine in a cheap whorehouse.  Do you know if he has a seizure disorder or diabetes?  No, huh.  Well, there must be other drugs besides meth in his system, then.  Cool.  Thanks for your help.  Have a good one…”

Scoop or Droop

What interesting findings do you note on this ECG?

Click to enlarge. Go ahead, click it.  It won't hurt.

It is slow atrial fibrillation (some would even call it fib-flutter) at a rate between 40 and 60-ish with normal axis.  There is also T wave flattening, a short QTc (the top part that I cropped off says 0.402), U waves, and sagging inferior/lateral ST segments. 

What does all that mean?  Digoxin.

Digoxin is a cardiac glycoside commonly extracted from the foxglove plant:

Digitalis lanata in the Jardin des Plantes, Paris. Public domain.
Photo credit.

 It is used most often for rate control in atrial fibrillation and to increase contractility in congestive heart failure.  There are three main effects:

• It slows conduction through the AV node, which helps slow atrial fibrillation
• It increases cardiac automaticity (the ability of heart cells to initiate depolarization without external stimuli)
• It increases myocardial contractility, which helps in congestive heart failure

There are four main ECG findings that you see in patients with therapeutic levels of digoxin.  The first are T wave changes, such as flattening, inversion, terminal peaking, and such.  Second, the QT interval shortens due to decreased ventricular repolarization time.  In addition, U waves are commonly seen.  Finally, the ST segments sag – usually referred to as the “dig scoop.”  This is especially visible in leads with tall R waves (inferior and lateral leads).  Take a minute to look at the ECG above and pick out each of those findings.

This leads me to a brief and unimportant rant: Everyone has heard the term “Dig scoop.”  I think it looks less like a scooped ST segment than it does a sagging or drooping ST segment.  It isn’t scooped like someone grabbed some baseline-flavored ice cream.  The ST segments sag, like they’re tired.  So I like the term “dig droop.”  I think it is slightly more accurate, plus it has the double-D alliteration.

They are drooping, not scooped! Also, note the U waves.
Photo credit (Public domain)

Toxic levels of dig can result from chronic or acute processes.  Chronic toxicity presents with nonspecific complaints like weakness and malaise (unhelpful complaints in the older population, huh?).  Visual disturbances like light halos are actually pretty rare, but can occur.  On top of the digitalis toxicity, CHF patients can have jumbled electrolyte levels from diuretic use that complicates the clinical picture.

The signs of acute poisoning revolve around the main effects of digoxin: slowed conduction through the AV node and increased automaticity.  Physical complaints usually involve nausea and vomiting.  Electrocardiographic effects include essentially any dysrhythmia (outside of bundle branch blocks and rapid AFib).  The increase in automaticity can result in PVCs – uniform, multiform, bigeminy, trigeminy, and such. The decreased AV conduction results in heart blocks, from first to third degree.* 

Three main dysrhythmias that should make you immediately consider digoxin toxicity are atrial tach (usually with a block), junctional tach, and ventricular tachycardia.  VTach can be nutty too, with stuff like bidirectional and alternating VTachs.(1)  Those are good to remember, but anytime your brain recoils from the weirdness of a rhythm on the monitor – think of digoxin.  When the ECG looks like two people holding hands, think of dig.  In my experience, digoxin makes for weird rhythms that need plenty of work and calipers to work through.

The management of dig-toxic patients depends on whether they are stable or not.  Stable patients usually just get to skip a few doses of digoxin to lower their levels.  Unstable patients are more complex.  Dysrhythmias are treated per ACLS, with pacemakers, ventricular antiarrhythmics, and such.  Electrolyte levels are corrected, and severely toxic patients can be given digoxin-specific Fab fragments (Digibind) as a kind of antidote.  Prehospital providers can’t screw with electrolyte levels and Digibind isn’t in my formulary.  So I guess it’s lucky that we’re good at ACLS in the field, isn’t it?  That is essentially all we are left with. 

If you want to get deeper into dig and how it works, you’re on your own.  Make sure to check out the article cited below by Gene Ma et al., and Life in the Fast Lane, ECGpedia, UpToDate, and other websites have good information.  Enjoy.

*If you want a real headache, heart blocks can result in (sort of) regular AFib: A complete heart block with slow, regular junctional escape. How’s that for fun?

1. Ma G, Brady WJ, Pollack M, Chan TC. Electrocardiographic manifestations: Digitalis toxicity. J Emerg Med 2001;20(2):145-52.

Energy, But Not the Hippie Kind

You and your partner respond to a small house on the report of a pediatric sick case. Upon arrival you find an 8 year old who seems to have the flu. Not a big deal – the kid is sick, but not sick-sick. Mom seems especially fearful, though, and Dad seems to be angry. He is pacing around with tension in his jaw and neck, his eyebrows are tense and together, and his hands are carried as fists. He is overbearing in his efforts to be involved in the call and his voice is louder than normal conversation. You explain what is going on, and that the child isn’t in danger. You calmly and confidently explain the best way to treat the child’s symptoms and ask if the parents have questions. Mom’s fear seems to be lessened to a great extent, but Dad is still all kinds of fired up.

Weird, right? Why is Dad so upset?

There used to be a show on TV called “The Dog Whisperer.” It was a reality show about a trainer, Caesar Millan, who could get most out-of-control dogs to behave. I don’t know much about dog training, his methods, or whether his ideas are accepted. One thing he said, though, resonated with me. It is the concept of energy. Not everyone holds this dog training theory as true, but it serves as a fine model for this topic.

Millan explains that “energy” is the main way that dogs communicate: “Energy is what I call beingness; it is who and what you are in every moment. Dogs don't know each other by name, but by the energy they project...” This isn’t energy as a kinetic force, or as a hippie-style energy field. Energy isn’t how much work you’re willing to do, or if you feel like vegging on the couch. Millan is talking about the outward expression of one’s mindset and emotional state. 

Patients and bystanders project their energy, as well. Some patients have fearful energy, some are calm, and some have aggressive energy exploding out of them. Think about the last five cops you saw. I bet you saw some mix of bored, impatient, irritable, and aggressive energy coming from the cops, right? Ever come home, see your spouse, think “oh, shit,” and start thinking about what you may have done that s/he is mad about before a word is even said? Your spouse was projecting angry energy. Have you ever watched someone and thought, “They are in a hurry…” They were projecting rushed or impatient energy. You can tell when a stranger is angry, or when a person is about to blow up at their kids. We can easily recognize the energy that people give off.

The important thing in EMS is to recognize energy and see that it matches the setting. It makes sense for a parent to be fearful when their child is injured. It makes sense for a police officer to be aggressive during a felony traffic stop. But when the situation is more secure, people’s energy should calm and become more stable. Acting fearful in a secure environment is weird. There may be more story that you are missing. A calm bystander in a dramatic environment is weird. Why are they so calm?

I’m not going to get into signs of different energies – you already know them, being a minimally functioning member of society. Even children can recognize fear, anger, calm, and other emotions. 

Credit, via Wikimedia Commons CC BY 4.0

The point that I want to make sure you understand is that we are taught in school to look for things that make a scene safe or unsafe. Whether there are weapons visible, whether the dog is locked away, and those kinds of very basic things. The energy of the scene is probably more important, however. Patients and bystanders are armed all the time and dogs are present on many scenes. But there is a difference between a man with a knife in his pocket (or even a concealed firearm) when his energy is calm and relaxed versus when he is agitated, confused, upset, or angry. A lady with a quiet, controlled dog on a leash is a different story from the lady screaming threats and profanities at you with the dog straining at the leash. The energy state that is projected by the person makes a huge difference in the relative level of safety.

The ability to listen to your subconscious when it is trying to tell you that something is wrong on the scene emotionally (energetically?) is critical to keeping you safe. 

Increase your safety by paying attention to the emotional energy that people are giving off.