Notable Aberrancies

     A significant part of the learning process for EMS providers is committing to memory the various numerical values that serve as baselines for patient assessment. At a minimum, that entails getting a handle on baseline respiratory rates, pulse ranges and blood pressures for infants, children, adults and geriatrics.

     In the field, it's quite challenging to decide when a change from baseline becomes significant and requires attention. Take, for example, the normal adult respiratory rate of 12 to 20. The common philosophy is that anyone breathing at a rate of 10 or less or 30 or more needs assisted ventilations. The truth is, you can have a patient breathing slow and deep at a rate of 10 who is doing just fine and another at 12 with shallow breathing who is in real trouble. The importance is not just memorizing a truckload of numerical values. It's developing an understanding of when a deviation from standards, aka an aberrancy, becomes significant.

     This month, we look at four aberrancies I believe are worth noting on any call.

Sustained/Progressive Tachycardia
      It is quite common to find your patients in some form of tachycardia. A sudden onset of difficulty breathing, the feeling that your throat is swelling shut, or sliding your car off an icy highway into a telephone pole are just a few of many events that will get your ticker racing. That is a normal physiologic response and is to be expected. However, within a few minutes after you arrive on scene, you should expect your patient to calm down, with a corresponding slower heart rate.

     Your first red flag is sustained or progressive tachycardia, in which case there are two issues to immediately consider. First, a sustained tachycardia implies that whatever is causing the problem remains a problem.

     In addition, sustained tachycardia is linked to increased cardiac workload, as well as increased cardiac O₂ consumption. Neither is desirable in any patient, and both can be even more problematic in the very young or very old. With progressive tachycardia, the message is clear: Things are getting worse. Whether the cause is fluid loss, a failing heart, licit/illicit substance abuse, etc., finding and correcting it is imperative.

Inability to Maintain Adequate O₂ Saturation
      By definition, a patient with a lower than 90% oxygen saturation level has hypoxemia. Frequently, simple administration of 4 to 6 lpm of oxygen via cannula will quickly correct the problem. The second notable aberrancy is the patient who cannot maintain his O₂ saturation in spite of supplemental oxygen therapy.

Slowing Respirations/Ventilatory Failure
      Even on routine calls, there's a lot going on in the back of the ambulance. Add to that the challenge of working in a small environment while bouncing and weaving down the highway and you have a medical environment like no other. Given that, it is easy to see how things can slip through the cracks.

     What cannot be allowed to slip through the cracks are the two classic signs of ventilatory fatigue. Most providers are glad when their patient calms down, as that is one less distraction in the grand scheme of the call. However, it is critical to determine whether the patient is actually just calming down or is starting to spiral down the tubes. When your patient begins to calm down, it's time to recheck vitals. Assuming you already have baseline vitals, a second set provides comparative data, and a third set allows you to map trends. One trend that is a huge red flag is when a previously tachypneic patient progresses to a sub-optimal rate and now presents as a lethargic, hypoventilating patient. Miss the signs of ventilatory fatigue, especially in a child, and the next wakeup call will be when the patient goes into cardiac arrest.

Altered/Decreasing Mentation
      One of the most easily missed clinical signs is altered or decreasing mentation. One of the best ways to continually assess your patient's mentation is by maintaining a dialogue with him. As you gather more history and follow up on how your interventions are working, try not to focus solely on "information content," but also on mental performance. The brain requires a constant supply of oxygen and sugar to function, yet can store neither. Altered or decreasing mentation requires immediate evaluation of O₂ saturation and sugar levels, both of which can be addressed in the field setting. Once these two critical elements are addressed and you determine they aren't the causative factors, you can continue to explore further, but don't miss the two most common quick fixes for altered/decreasing mentation. To facilitate this evaluation, talk to your patient--a lot. You can provide continuous psychological support while keeping on top of the patient's mentation level.

Conclusion
      The four items listed above are cornerstones of prehospital care that help make sense of the many values you have committed to memory, and, in turn, improve your patient care efforts.

     Until next month...

Mike Smith, BS, MICP, is program chair for the Emergency Medical Services program at Tacoma Community College in Tacoma, WA, and a member of EMS Magazine's editorial advisory board.