Are Vital Signs Vital?

Review of:Chen L, Reisner AT, Gribok A: “Exploration of prehospital vital sign trends for the prediction of trauma outcomes.” Prehospital Emergency Care. 13(3):286 294, 2009.

The Science
The authors of this study attempted to look at trends and averages in vital signs of trauma patients in the prehospital setting. The investigators obtained data from 2001 2004 from EMS flight teams transporting patients to the Level 1Unit of Memorial Hermann Hospital in Houston. Vital signs were measured using the Propaq 206EL transport monitor, and other attribute data was retrospectively collected through EMS charts.

The focus was on trauma patients who required a blood transfusion within 24 hours of admission to the hospital. A total of 897 patients in a three-year span qualified for the study, however, only 97 (11%) patients fit the initial inclusion criteria. The authors then made the inclusion criteria less stringent and ran various statistical analyses to look for trends in vital signs.

The methods and results sections are extremely technical and full of statistical jargon, but the authors are clearer in the discussion section of the paper. They conclude vital signs in the trauma patient are too variable in the prehospital setting to give any sort of prediction on the outcome of the patient.

The Street
Namely, the authors concluded that vital signs aren’t a good predictor of how patients are actually compensating for shock.

Doc Wesley:I’m not sure what to make of this study. It’s more a study in statistics than a true clinical study. To avoid boring you to death, I’ll simply say the researchers only eliminated the majority of their subjects because they didn’t have “valid” vital signs. They were only comparing the vital signs obtained during the first 10 minutes of flight with the second 10 minutes of flight, since the majority of flights lasted only 20 minutes. Additionally, they arrived at the scene 40 minutes after the injury and didn’t use the ground crews’ vital signs.

Finally, their primary outcome for major trauma (hemorrhage patients) was those who received a blood transfusion. This is not a standard definition in trauma research and could affect their results. So overall, while I agree with their conclusion, I don’t believe they proved it with this research.

Medic Marshall:So what does that mean for us street folks? Well, vital signs are still important and we shouldn’t stop doing them as a result of this paper. What it does say is trauma patients have bad vital signs (who knew?) and implies that some trauma patients may be more injured than their vital signs indicate.

For example, if a patient who was the un-seat belted driver of a sport utility vehicle that rolled over at high-speed is walking around on scene, they may be far more injured than the vitals (B/P: 146/90, RR: 20, HR: 100, SaO2: 98%) tell.

Mechanism of injury suggests the patient ought to be transported to a Level I Trauma Center, though the vitals are fairly close to normal range. Furthermore, those vital signs shouldn’t keep us from providing other care, such as putting the patient in full spinal immobilization precautions, starting two large-bore IVs (maybe even blood tubing), and putting them on a cardiac monitor.

In the end, patient care is complex, and we sometimes need to be reminded that the whole (patient care) is greater than the sum of its parts (i.e., vital signs, mechanism of injury and medical history.)

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