Answer: This is a terrific question. If you are looking for a “Yes or No”, the answer is a “No”. That being said, in order to answer this great question properly, it is important to understand why and how the wording in the directive was chosen.
In the past, a frequently asked question was the definition of “chest pain”. For instance, ischemic discomfort described by patients is often a “tightness” or a “heaviness” (along with a myriad of other variations upon this theme). If “chest pain” was used in the directive, then in some cases, paramedics were not administering NTG since in the strictest sense; the patient was not having “pain”. This is why the wording “suspected cardiac ischemia” was chosen: to avoid this debate and allow paramedics to decide if the discomfort being experienced by their patient was consistent with cardiac ischemia. The key word here however is discomfort…
Now, with that said, let’s answer your specific question. Symptoms like you are describing (weakness, shortness of breath, nausea and vomiting) are vague. While these symptoms absolutely may be consistent with cardiac ischemia, they also may be associated with a myriad of other conditions other than cardiac. You mention coupling these symptoms with a “positive 12 lead”. While this would absolutely make sense and would heighten the suspicion that this discomfort is coming from a cardiac etiology, ST elevation and depression may be chronic in nature and this could be misleading. We are fortunate in the ED to often have the “old ECG” to compare for baseline purposes in these difficult cases. It is also not an expectation of all paramedics to perform manual ECG interpretation to determine if the subtle changes found on ECG’s are consistent with acute ischemia.
In essence, a patient could be short of breath, have nausea, diaphoresis, and an abnormal ECG such as a left bundle branch block (which is chronic) and the underlying condition may be anxiety or gastro. In that case, administering NTG would clearly not be indicated and may result in a drop in blood pressure.
Finally, when administering NTG, it is important to evaluate the response of the patient to each dose not only in changes to vital signs, but also in terms of symptoms. This is why discomfort of some form is important: it allows the paramedic to track improvements in that discomfort with subsequent doses. Vague symptoms such as diaphoresis or nausea or shortness of breath are not readily amenable to a linear response to subsequent doses of NTG as evaluated by paramedics on scene. So, with all of that said, here is the answer.
It is the intent of the SWORBHP Medical Directors that the definition of “suspected cardiac ischemia” in order to meet the indications for NTG administration should encompass some form of discomfort which is consistent with cardiac etiology which in turn would allow a paramedic to gauge the response and indicate the need for further NTG administration.