All posts by The Trauma Pro

Equipment

The Lowly Blood Pressure Cuff: Is It Accurate?

Leave a comment

Yesterday, I described how the typical automated oscillometric blood pressure cuff works. We rely on this workhorse piece of equipment for nearly all pressure determinations outside of the intensive care unit. So the obvious question is, “is it accurate?”

Interestingly, there are not very many good papers that have ever looked at this! However, this simple question was addressed by a group at Harvard back in 2013. This study utilized an extensive ICU database from 7 ICUs at the Beth Israel Deaconess Medical Center. Seven years of data were analyzed, including minute by minute blood pressure readings in patients with both automated cuffs and indwelling arterial lines. Arterial line pressures were considered to be the “gold standard.”

Here are the factoids:

  • Over 27,000 pairs of simultaneously recorded cuff and arterial line measurements from 852 patients were analyzed
  • The cuff underestimated art line SBP for pressures at or above 95 torr
  • The cuff overestimated SBO for pressures below 95 torr (!)
  • Patients in profound shock (SBP < 60) had a cuff reading 10 torr higher
  • Mean arterial pressure was reasonably accurate in hypotensive patients

sbp-cuff-v-aline

Bottom line: The good, old-fashioned automated blood pressure cuff is fine for patients with normal pressures or better. In fact, it tends to understimate the SBP the higher it is, which is fine. However, it overestimates the SBP in hypotensive patients. This can be dangerous! 

You may look at that SBP of 90 and say to yourself, “that’s not too bad.” But really it might be 80. Would that change your mind? Don’t get suckered into thinking that this mainstay of medical care is perfect! And consider peeking at the mean arterial pressure from time to time. That may give you a more accurate picture of where the patient really is from a pressure standpoint.

Related posts:

Reference: Methods of blood pressure measurement in the ICU. Crit Care Med Journal, 41(1): 34-40, 2013.

Equipment

How Does It Work? The Lowly Blood Pressure Cuff

Leave a comment

The blood pressure cuff is one of those devices trauma professionals don’t give a second thought to. Old timers like me remember using the cuff with a sphygmomanometer and stethoscope to get manual blood pressures. I’ve had to do this twice in recent months on airplanes, and I had forgotten how much work this is.

But technology makes things easier for us. Now you just slap a cuff on the arm (or wrist), push a button, and voila! You’ve got the pressure.

But have you stopped to think about how this actually works? Why don’t we need the stethoscope any more? Here’s the scoop:

When you take a manual blood pressure, the cuff is inflated until a pulse can no longer be auscultated with the stethoscope. The pressure is slowly released using a little thumb wheel while listening for the pulse again. The pressure at which it is first audible is the systolic, and the pressure at which it softens and fades away is the diastolic.

The automatic blood pressure device consists of a cuff, tubing that connects it to the monitor, a pressure transducer in line with the tubing, a mini air pump, and a small computer. The transducer replaces the analog pressure gauge, and the pump and computer replace the human.

The transducer can “see” through the tubing and into the cuff. It is very sensitive to pressure and pressure changes. The computer directs the pump to inflate to about 20 torr above the point where pulsations in the air column cease. It then releases the pressure at about 4 torr per second, “feeling” for air column vibrations to start. Using a manufacturer specific computer algorithm, the mean arterial pressure is measured. A little more proprietary calculation results in an estimated systolic and diastolic pressure.

bpcuff

Piece of cake! But here’s the question: is it accurate? Tomorrow, I’ll write about how the automated cuff compares to an indwelling arterial line.

Related post:

How to

How To: The Serial Abdominal Exam

Leave a comment

How often have you seen this in an admitting history and physical exam note? “Admit for observation; serial abdominal exams.” We say it so often it almost doesn’t mean anything. And during your training, did anyone really teach you how to do it? For most trauma professionals, I believe the answer is no.

Yet the serial abdominal exam is a key part of the management of many clinical issues, for both trauma patients as well as those with acute care surgical problems.

Here are the key points:

  • Establish a baseline. As an examiner, you need to be able to determine if your patient is getting worse. So you need to do an initial exam as a basis for comparisons.
  • Pay attention to analgesics. Make sure you know what was given last, and when. You do not need to withhold pain medications. They will reduce pain, but not eliminate it. You just need enough information to determine if the exam is getting worse with the same amount of medication on board.
  • Perform regular exams. It’s one thing to write down that serial exams will be done, but someone actually has to do them. How often? Consider how quickly your patient’s status could change, given the clinical possibilities you have in mind. In general, every 4 hours should be sufficient. Every shift is not. And be thorough!
  • Document, document, document. A new progress note should be written, dated and timed, every time you see your patient. Leave a detailed description of how the patient looks, vital signs, pertinent labs, and of course, exact details of the physical exam.
  • Practice good handoffs. Yes, we understand that you won’t be able to see the patient shift after shift. So when it’s time to handoff, bring the person relieving you and do the exam with them. You can describe the pertinent history, the exam to date, the analgesic history, and allow them to establish a baseline that matches yours. And of course, make sure they can contact you if there are any questions.
General

Jehovah’s Witnesses And Blood Transfusion Demystified

Leave a comment

Injury can be a bloody business, and trauma professionals take replacement of blood products for granted. Some patients object to this practice on religious grounds, and their health care providers often have a hard time understanding this. So why would someone refuse blood when the trauma team is convinced that it is the only thing that may save their life?

Jehovah’s Witnesses are the most common group encountered in the US that refuse transfusion. There are more than 20 million Witnesses worldwide, with over 7 million actively preaching. It is a Christian denomination that originated in Pennsylvania during the 1870s.

Witnesses believe that the bible prohibits taking any blood products, including red cells, white cells, platelets or plasma. It also includes the use of any dialysis or pump equipment that must be primed with blood. This is based on the belief that life is a gift from God and that it should not be sustained by receiving blood products. The status of certain prepared fractions such as albumin, factor concentrates, blood substitutes derived from hemoglobin, and albumin is not clear, and the majority of Witnesses will accept these products. Cell saver techniques may be acceptable if the shed blood is not stored but is immediately reinfused.

Why are Witnesses so adamant about refusing blood products? If a transfusion is accepted, that person has abandoned the basic doctrines of the religion, and essentially separates themselves from it. They may then be shunned by other believers.

So what can trauma professionals do to provide best care while abiding by our patient’s religious belief? In trauma care it gets tricky, because time is not on our side and non-blood products are not necessarily effective or available. Here are some tips:

  • Your first duty is to your patient. Provide the best, state of the art care you can until it is absolutely confirmed that they do not wish to receive blood products. In they are comatose, you must use blood if indicated until the patient has been definitively identified by a relative who can confirm their wishes with regard to blood. Mistaken identity does occur on occasion when there are multiple casualties, and withholding blood by mistake is a catastrophe.
  • Talk with the patient or their family. Find out exactly what they believe and what they will allow. And stick to it.
  • Aggressively reduce blood loss in the ED. We are not always as fastidious as we should be because of the universal availability of blood products. Use direct pressure or direct suture ligation for external bleeding. Splint to reduce fracture bleeding.
  • Aggressively use damage control surgery. Don’t go for a definitive laparotomy which may take hours. Pack well, close and re-establish normal physiology before doing all the final repairs.
  • Always watch the temperature. Pull out all the stops in terms of warming equipment. Keep the OR hot. Cover every bit of the patient possible with warming blankets. All fluids should be hot. Even the ventilator gases can be heated.
  • Think about inorganic and recombinant products such as Factor VIIa, tranexamic acid and Vitamin K. These are generally acceptable.
  • Consider angiography if appropriate, and call them early so their are no delays between ED and angio suite or OR and angio suite.

Bottom line: Do what is right for your patient. Once you are aware of their beliefs, avoid the use of any prohibited products. Speak with them and their family to clarify exactly what you can and cannot do. This is essentially an informed consent discussion, so make sure they understand the consequences. Follow their wishes to the letter, and don’t let your own beliefs interfere with what they want.

Technology

The Electronic Trauma Flow Sheet: Oops! Now What Are My Options? Part 2

Leave a comment

Yesterday, I discussed what to do if your hospital is thinking about switching to an electronic trauma flow sheet (eTFS). Today I’ll give you some tips on what to do if the cat’s already out of the bag and it’s already been implemented.

The number one priority is to show the impact of the eTFS on the trauma program. There are two components:

  1. Accuracy. The trauma program must measure the impact of the “garbage in” phenomenon on the performance improvement (PI) process. This is critically important, because bad data will decrease the quality of your PI analysis. For example, if the PI program is not able to determine that hypotensive patients are being taken to CT scan, patient harms could occur that are not detected. This could result in two bad things for your trauma program (and patients): unanticipated mortality and deficiencies during a verification visit.
    Be on the lookout for extraneous or impossible data points. Keep a list of information that is consistently missing. Use all of this information work with your hospital administration to find ways to make it better.
  2. Efficiency.  Your program must also find a way to measure the efficiency of abstraction by the trauma program manager, PI coordinator, registrars, or whoever is tasked with doing it. Keep track of the time needed to abstract a trauma activation chart vs a non-activation. This will give you an idea of the extra time needed to process the eTFS data. Or just clock in when starting eTFS abstraction, and clock out when finished. The amount of time will probably astonish you.
    Monitor average days to completion of registry entries, and look at the number of cases not fully abstracted by 60 days to see if there is a noticeable impact on your registry concurrency. Delays here are common in centers with high volumes of trauma activations, because the abstractors must spend an inordinate amount of time trying to pull information from the eTFS.

Once your hospital has taken the plunge and adopted the eTFS, it is very difficult to go back. Many centers are convinced that “this next update is going to make it so much better.” It never does! I have visited programs that have been tweaking their processes and reports for almost 8 years! None have been able to improve it significantly.

Your hospital administration will ultimately need to decide how to proceed, depending on how damaging the eTFS is to the trauma PI program and how much it will cost to continue to tweak it vs returning to a paper flow sheet. Good luck!