By David Jaslow
Traditional vital signs are those taught in every EMT and paramedic course and can be measured with minimal technology: pulse, blood pressure, respiratory rate and temperature. Whether it is best to measure these manually or electronically is actually a fairly complex issue and it will be addressed in a later column. Non-traditional vital signs are physiologic values, which must be obtained through technological means. I believe that this information is so important that it deserves to be classified as a vital sign by the very nature of the meaning of the term, although others may disagree.
The non-traditional vital signs include pulse oximetry, end tidal CO2 and carbon monoxide values. These could be labeled as the fifth, sixth and seventh vital signs. Note that blood glucose level, which many emergency physicians and paramedics consider to be another non-traditional vital sign, is excluded here only because hypoglycemia is not considered to be either a common or life-threatening fireground medical emergency.
Given that we have defined that one of the characteristics of the fireground medical screening exam is that it can be accomplished without any invasive procedures, blood glucose measurement will not be discussed further.
The first and most important parameter in terms of its relationship to heat stress — and whether this has been adequately decreased — is heart rate. The primary determinant is tachycardia. Every firefighter coming out of the operations sector will be tachycardic if they have done significant physical labor even if they are on medications which slow heart rate. Therefore, everyone starts out tachycardic. However, theoretically, nobody should be tachycardic when they leave the rehab sector. As the heart rate is known to be due in part to heat load, recommendations have been consistently promulgated that firefighters should immediately take off as much PPE as is reasonable given environmental conditions, and consume cool liquids (water) to decrease the heart rate in the rehab sector.
Rehab documents
I continue to be surprised to see that various rehab documents list heart rates as 110 or 120, clearly defined as tachycardic in the medical world, as criteria to safely exit the rehab sector. I am even more surprised that they do not offer any explanation as to how they have arrived at this number. But I'm most surprised that there is no explanation about the most important aspect of higher than normal heart rates, which is to attempt to assign a reason or explanation to the abnormal value. Why the firefighter continues to be tachycardic after appropriate rest, rehydration and a medical screening exam is more important than the exact beats per minute.
The differential of tachycardia includes many conditions that are out of the scope of understanding of the average paramedic (let alone the EMT-Basic). Releasing fire personnel back to active duty in the setting of abnormal vital signs may constitute negligent medical practice, and it's necessary for the rehab sector officer to do everything possible to either achieve heart rates less than 100 or make an intervention which will diagnose a medical condition causing the tachycardia and/or decrease it. Further discussions about firefighter physiology on the fireground are beyond the scope of this series, but The University of Pittsburgh is currently investigating this issue and should be publishing studies within the next two years.
As tachycardia has many causes, the best way to detect whether or not it is pathologic in a firefighter during the rehab process is to observe the response to rest and rehydration. Those who have underlying reasons driving a fast heart rate are unlikely to see that tachycardia completely resolve, whereas individuals who are just physically exhausted, suffering from heat stress and/or mildly dehydrated should rapidly improve. A general rule of thumb is that unexplained vital signs abnormalities should never be ignored. They should be brought to the attention of the rehab sector officer who will follow a SOP and a medical protocol about how to interpret and respond to these findings.
There is no need to measure an exact respiratory rate among firefighters in rehab. We can draw a parallel argument to the tachycardia example: every firefighter coming into rehab from an active and heavy work environment will be breathing somewhat faster and deeper than normal. This is a normal physiologic response to hyperthermia, increased metabolic workload and physical and emotional stress. It is the inability to breath at a normal rate once sufficiently rested which is the abnormality to be concerned about.
Anyone with moderate to severe respiratory distress will also have tachycardia (unless they are in a pre-code setting when they are bradying down), hypoxia and may have hypertension as well. Obtaining these other vital signs will provide all the information you need without having to measure an exact respiratory rate. Only those firefighters who appear to have respiratory distress in the setting of an elevated respiratory rate need immediate medical attention. Presumably, they'll also be complaining of trouble breathing. Signs to look for include prolonged tachypnea, accessory muscle use, audible wheezing or rhonchi, continuous coughing, hypoxia (via pulse ox) or other respiratory abnormality. Difficulty breathing can be subtle, but most firefighters will complain of this right away so that it will be obvious in the "hasty exam" portion of the rehab process.
In the next column, we will address blood pressure and temperature followed by non-traditional vital signs.
Previous articles in this series:
Fireground Medical Screening Exam – Part 1
Fireground Medical Screening Exam – Part 2
Fireground Medical Screening Exam – Part 3
Fireground Medical Screening Exam – Part 4
Fireground Medical Screening Exam – Part 5
David Jaslow, MD, MPH, FAAEM is a board certified emergency physician who is fellowship trained in EMS and disaster medicine. He is the director of the Division of EMS and Disaster Medicine within the Department of Emergency Medicine at Albert Einstein Medical Center in Philadelphia. Dr. Jaslow is a state-certified Firefighter I and he is credentialed by the Pennsylvania Department of Health as a pre-hospital physician. He functions as a chief officer in several suburban Philadelphia fire and EMS agencies and provides medical oversight as the lead physician for the Bucks County Technical Rescue Task Force as well as Pa. Task Force-1 Urban Search and Rescue.
