Category Archives: Equipment

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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CT Contrast Via Intraosseous Catheter

The standard of care in vascular access in trauma patients is the intravenous route. Unfortunately, not all patients have veins that can be quickly accessed by prehospital providers. Introduction of the intraosseous device (IO) has made vascular access in the field much more achievable. And it appears that most fluids and medications can be administered via this route. But what about iodinated contrast agents via IO for CT scanning?

Physicians at Henry Ford Hospital in Detroit published a case report on the use of this route for contrast administration. They treated a pedestrian struck by a car with a lack of IV access sites by IO insertion in the proximal humerus, which took about 30 seconds. They then intubated using rapid sequence induction, with drugs injected through the IO device. They performed full CT scanning using contrast injected through the site using a power injector. Images were excellent, and ultimately the patient received an internal jugular catheter using ultrasound. The IO line was then discontinued.

This paper suggests that the IO line can be used as access for injection of CT contrast if no IV sites are available. Although it is a single human case, a fair amount of studies have been done on animals (goats?). The animal studies show that power injection works adequately with excellent flow rates.

The authors prefer using an IO placement site in the proximal humerus. This does seem to cause a bit more pain, and takes a little practice. A small xylocaine flush can be administered to reduce injection discomfort in awake patients. Additionally, the arm cannot be raised over the head for the torso portion of the scan.

Bottom line: CT contrast can be injected into an intraosseous line (IO) with excellent imaging results. Insert the IO in a site that you are comfortable with. I do not recommend power injection at this time. Although the marrow cavity can support it, the connecting tubing may not. Have your radiologist hand-inject and time the scan accordingly. And don’t be surprised if your radiology department doesn’t have a protocol for this!

Note: long term effects of iodinated contrast in the bone marrow are not known. For this reason, and because of smaller marrow cavities, this technique is not suitable for pediatric patients.

Related posts:

Reference: Intraosseous injection of iodinated computed tomography contrast agent in an adult blunt trauma patient. Annals Emerg Med 57(4):382-386, 2011.

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Trauma In Pregnancy 6: C-Section – Tools

Most emergency departments do not have a separate perimortem C-section pack sitting on the shelf. And when you finally need it, that is not the time to make one up. Most emergency departments have some type of major cutdown or mini-laparotomy tray available. Here is the absolute minimum required. Make sure these are on your existing tray.

  • Large scalpel – note that this should be a disposable type that is opened and dropped onto the tray
  • 3 large retractors for the helpers
  • Toothed forceps
  • Metzenbaum scissors
  • Heavy scissors
  • Multiple large clamps and hemostats

Yup, that’s all the heavy equipment you really need!

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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.

Related posts:

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. When this occurs, the systolic pressure is recorded. Deflation continues until the vibrations stop, representing the 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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