Category Archives: Equipment

How To Measure Your Trauma Bay

Yesterday I detailed some standard info on trauma bay size. Today, I’ll describe what I found when I brought in my trusty tape measure today to check out my trauma bays at Regions Hospital. I came up with several helpful measurements to help gauge the relative utility of the rooms.

Here are the indices that I came up with:

  • TBTA: Trauma Bay Total Area. This is the total square footage (meterage?) measured wall to wall.
  • TBWA: Trauma Bay Working Area. This is the area that excludes equipment carts next to a wall, and areas under countertops that extend away from the wall.
  • TBAA: Trauma Bay Available Area. This is the TBWA less any other unusable areas in the room. We have an equipment post near one corner that eats up 16.5  sq ft of space. Also remember to subtract the area taken up by the patient bed, as this area is not available to the trauma team, either.
  • TBSI: Trauma Bay Space Index. This value is derived by dividing the TBAA by the number of team members in the room. It gives an indication of how much space is available for each trauma team member to work in.

Values in my trauma center:

  • TBTA: 291 sq ft
  • TBWA: 220.5 sq ft
  • TBAA: 186.5 sq ft
  • TBSI: 15.5

What does it all mean? Hard to say without more info from you for comparison. For my team, it means we each have a 4×4 foot square to move around in, on average. This is fairly tight, I would say.

Why don’t you generate some comparison data? Tomorrow is “take a tape measure to work” day! Calculate these constants in your own resuscitation room. Then post them by leaving comments below, or tweet/email me the values for the metrics listed above. If I get enough, I’ll post the data here!

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How Big Should Your Trauma Bay Be?

I recently received a reader request regarding trauma bay design. Today, I’ll rerun my article on trauma bay size. Tomorrow, I’ll describe my system for quantifying the space in your trauma bay. Finally, next week I will address equipment layout in the resuscitation room.

Trauma resuscitation rooms vary tremendously. They can range from very spacious…

to very tight…

Most trauma bays that I have visited were somewhere between 225 and 300 square feet (21-28 sq meters), although some were quite large (Rashid Hospital in Dubai at nearly 50 sq meters!).

Interestingly, I did manage to find a set of published guidelines on this topic. The Facility Guidelines Institute (FGI) develops detailed recommendations for the design of a variety of healthcare facilities. Here are their guidelines for adult trauma bays:

  • Single patient room: The clear floor area should be 250 sq ft (23 sq m), with a minimum clearance of 5 feet on all sides of the patient stretcher.
  • Multiple patient room: The clear floor area should be 200 sq ft (18.5 sq m) with curtains separating patient areas. Minimum clearance of 5 feet on all sides of the patient stretcher should be maintained.

The FGI “clear floor area” corresponds to my “Trauma Bay Working Area”, which is the area that excludes all the carts, cabinets, and countertops scattered about the usual trauma room. California’s guideline of 280 sq feet seems pretty reasonable as the “Trauma Bay Total Area”, if you can keep your wasted space down to about 30 sq feet.

Bottom line: Once again, don’t try to figure out everything from scratch. Somebody has probably already done it (designed a trauma bay, developed a practice guideline, etc). But remember, a generic guideline or even one developed for a specific institution may not completely fit your situation. In this case, the FGI guidelines say nothing about the trauma team size, which is a critical factor in space planning. Use the work of others as a springboard to jump start your own efforts at solving the problem.

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The Lowly Blood Pressure Cuff: Is It Accurate?

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.

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

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How Does It Work? The Lowly Blood Pressure Cuff

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.

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Off-Label Use of the Foley (Urinary) Catheter

Foley catheters are a mainstay of medical care in patients who need control or measurement of urine output. Leave it to trauma surgeons to find warped, new ways to use them!

Use of these catheters to tamponade penetrating cardiac injuries has been recognized for decades (see picture, 2 holes = 2 catheters!). Less well appreciated is their use to stop bleeding from other penetrating wounds.

Foley catheters can be inserted into just about any small penetrating wound with bleeding that does not respond to direct pressure. (Remember, direct pressure is applied by one or two fingers only, with no flat dressings underneath to diffuse the pressure). Arterial bleeding, venous bleeding or both can be controlled with this technique.

In general, the largest catheter with the largest possible balloon should be selected. It is then inserted directly into the wound until the entire balloon is inside the body. Inflate the balloon using saline until firm resistance is encounted, and the bleeding hopefully stops. Important: be sure to clamp the end of the catheter so the bleeding doesn’t find the easy way out!

Use of catheter tamponade buys some time, but these patients need to be in the OR. In general, once other life threatening issues are dealt with in the resuscitation room, the patient should be moved directly to the operating room. In rare cases, an angiogram may be needed to help determine the type of repair. However, in the vast majority of cases, the surgeon will know exactly where the injury is and further study is not needed. The catheter is then prepped along with most of the patient so that the operative repair can be completed.

Tomorrow: an off-label use for this catheter in abdominal trauma!

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