Focused observation of the patient can almost immediately yield clues as to their circulatory status. A relaxed, comfortable patient, readily engaging in conversation, has adequate perfusion of the brain and vital organs. Restlessness, with the unsettled patient fiddling with sheets or constantly moving to get comfortable, suggests that a more detailed assessment is required.

Noting the position of the patient, the possible use of accessory muscles signifies the extent to which the work of breathing and therefore the potential for respiratory compromise has increased. The respiratory and cardiovascular systems are interdependent; respiratory symptoms may be the presenting feature of cardiac problems. Severe dyspnoea (sensation of breathlessness) is a common feature of acute heart failure¹