What characteristic of a client's angina pain should prompt immediate call for emergency services?

In the context of angina, the characteristic that should prompt an immediate call for emergency services is when the pain continues after rest and nitroglycerin. This is crucial because it indicates that the client may be experiencing more than just stable angina or typical chest pain; it suggests a potential progression to unstable angina or a myocardial infarction (heart attack).

Stable angina usually resolves with rest and the use of nitroglycerin, which acts to relieve the pain by improving blood flow to the heart. If the pain persists despite these interventions, it signals that the heart is not receiving adequate oxygen, and there could be an underlying critical issue that requires urgent medical attention.

Other characteristics of angina pain, such as mild perspiration, occurrence after moderate exercise, or discomfort in the arms and jaw, while they may indicate the presence of angina, do not typically signify a medical emergency as urgently as persistent pain despite rest and medication. These symptoms may warrant further evaluation, but they are not immediate red flags indicating the need for emergency services. In contrast, ongoing pain after nitroglycerin is a pressing indication of a serious condition that cannot wait for a routine appointment or observation, highlighting the need for urgent intervention.