Category Archives: General

Treating Numbers: Pulse Oximetry

How many times has this happened to you? You walk into a young, healthy trauma patient’s room and discover that they have nasal prongs and oxygen in place. Or better yet, these items appear overnight on a patient who never needed them previously. And the reason? The pulse oximeter reading had been low at some point.

This phenomenon of treating numbers without forethought has become one of my pet peeves. Somehow, it is assumed that an oximetry value less than the standard “normal” requires therapy. This is not the case.

In young, healthy people the peripheral oxygen saturation values (O2 sat) are typically 96-100% on room air. As we age, the normal values slowly decline. If we abuse ourselves (smoking, working in toxic environments, etc), lung damage occurs and the values can be significantly lower. Patients with obstructive sleep apnea will have much lower numbers intermittently through the night. 

So when does a trauma inpatient actually need supplemental oxygen? Unfortunately, the literature provides little guidance on what “normal” really is in older or less healthy patients. Probably because there is no norm. The key is that the patient must need oxygen therapy. How can you tell? Examine them! Talk to them! If the only abnormal finding is patient annoyance due to the persistent beeping of the machine, they don’t need oxygen. If they feel anxious, short of breath, or have new onset tachycardia, they probably do. Saturations in the low 90s or even upper 80s can be normal for the elderly and smokers.

Bottom line: Don’t get into the habit of treating numbers without thinking about them. There are lots of reasons for the oximeter to read artificially low. There are also many reasons for patients to have a low O2 sat reading which is not physiologically significant. So listen, talk, touch and observe. If your patient is comfortable and has no idea that their O2 sat is low, turn off the oxygen and toss the oximeter out the window. 

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PAs and NPs In Level I Trauma Centers

Trauma service staffing is important to maintaining trauma center status. Teaching centers in the US have been grappling with resident work hour rules, and non-teaching centers have always had to deal with how to adequately staff their trauma service. What is the impact of staffing a trauma center with midlevel practitioners (MLPs) such as physician assistants and nurse practitioners?

A state designated Level I trauma center in Pennsylvania retrospectively examined the effect of adding MLPs to an existing complement of residents on their trauma service. They examined the usual outcomes, including complications, lengths of stay, ED dwell times and mortality. 

Here are the more interesting results:

  • ED dwell time decreased for trauma activations and transfers in, but it increased for trauma consults. Of note, data on dwell times suffered from inconsistent charting.
  • ICU length of stay decreased significantly
  • Hospital length of stay decreased somewhat but did not achieve significance
  • The incidence of most complications stayed the same, but urinary tract infection decreased significantly
  • There was no change in mortality

Bottom line: There is a growing body of literature showing the benefits of employing midlevel providers in trauma programs. Whereas residents may have a variable interest in the trauma service based on their career goals, MLPs are professionally dedicated to this task. This study demonstrates a creative and safe solution for managing daily clinical activity on a busy trauma service.

Reference: Utilization of PAs and NPs at a level I trauma center: effects on outcomes. J Amer Acad Physician Assts, July 2011.

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Prehospital Attitudes About Analgesia

Pain relief is important for two reasons: it’s the humane thing to do for someone who is suffering, and just as importantly, it assists in the physiologic response to trauma. There are several papers that have shown that prehospital providers may not use pain medications as much as they should. Why would this be?

Researchers at Yale released a paper describing a number of interviews with prehospital providers to get the answers to this question. They did individual and group interviews with five EMS agencies in the states of New Hampshire, Massachusetts and Connecticut. Eight individual and 2 group interviews were conducted, with a total of 15 paramedics in the study.

The results were very interesting and several themes emerged:

  • There was a reluctance to give opioids unless objective signs were present (deformity, hypertension)
  • There was a preoccupation that patients might be malingering
  • Paramedics were not clear on what the pain control target should be (complete relief vs “taking the edge off”)
  • Fear of masking symptoms with pain medicine
  • Reluctance to use large doses (e.g. using no more than 5mg morphine)

Bottom line: This study is very small, which is a problem. But it also used face to face interviews, so a lot of information was obtained. It’s hard to say if this work is representative of other agencies or countries, but it is thought provoking. My take is this: trauma hurts like hell. Patients really do need the medication. And they are not going to get addicted from a few doses while enroute to the hospital. Whether the cause of their injury was truly accidental or the result of poor choices, it’s not our place to judge because we don’t know the full story. Give pain medication and be generous. You’re not going to make the symptoms go away. But do use judgment to make sure they keep breathing all the way to the emergency department.

I’m very interested in EMS comments about this study. Please comment or tweet!

Reference: Paramedic attitudes regarding prehospital analgesia. Prehospital emergency care; Online ahead of print, Sep 2012.

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The EMS Second IV In Trauma

One of the critical maneuvers that EMS providers perform is establishing initial vascular access. This IV is important for administering medications and for initiating volume resuscitation in trauma patients. Prehospital Trauma Life Support guidelines state that every trauma patient should receive two large bore IV lines. But is this really necessary?

The upside of having two IVs in the field is that the EMS provider can give lots of volume. However, a growing body of literature tells us that pushing systolic blood pressure up to “normal” levels in people (or animals) with an uncontrolled source of bleeding can increase mortality and hasten coagulopathy.

The downside of placing two lines is that it is challenging in a moving rig, sterility is difficult to maintain, and the chance of a needlestick exposure is doubled. So is it worth it?

A group at UMDNJ New Brunswick did a retrospective review of 320 trauma patients they received over a one year period who had IV lines established in the field. They found that, as expected, patients with two IVs received more fluid (average 348ml) before arriving at the hospital. There was no increase in systolic blood pressure, but there was a significant increase in diastolic pressure with two lines. The reason for this odd finding is not clear. There was no difference in the ultimate ISS calculated, or in mortality or readmission.

Bottom line: This study is limited by its design. However, it implies that the second field IV is not very useful. The amount of extra fluid infused was relatively small, not nearly enough to trigger additional bleeding or coagulopathy. So if another IV does not deliver significant additional fluid and could be harmful even if it did, it’s probably not useful. Prehospital standards organizations should critically look at this old dogma to see if it should be modified.

Reference:

  • Study of placing a second intravenous line in trauma. Prehospital Emerg Care 15:208-213, 2011.
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Wounds: When Are They Too Old To Close?

At some point in their training, every trauma professional is taught that there is a certain period time during which a wound can be safely closed. The exact number varies, but is usually somewhere between 6 and 24 hours. After that, we are told, “bad things happen.”

Always question dogma, I say. Is this true, or is it another one of those “facts” that have been propagated through the ages? Two emergency medicine groups recently performed a meta-analysis to try to answer my question. As usual, they found that much of the published literature is not very good. Out of 418 papers in their original search, only 4 fully met their criteria (laceration repaired primarily, in the ED, with clear early vs delayed criteria.

With the exception of one study with a very limited focus, there was no correlation between wound age and infection or dehiscence after primary closure. None of the studies could reliably provide a specific time beyond which closure was destined to fail. And the use of antibiotics in some of the studies also confounded the results.

Bottom line: It is more likely that infection-prone wounds get infected, not old ones. Although leaving a wound open to heal by secondary intention usually avoids the problem, it’s a big patient dissatisfier, especially with large wounds. Since many patients don’t present to the ED until their wound is “old”, it may be reasonable to try primary closure in all but infection-prone wounds. (The meaning of that phrase is not exactly clear, but most of us know it when we see it.) 

Reference: The impact of wound age on the infection rate of simple lacerations repaired in the emergency department. Injury 43(11):1793-1798, 2012.

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