What is the cardinal symptom of paroxysmal nocturnal dyspnea (PND)?

Paroxysmal nocturnal dyspnea (PND) is characterized by episodes of severe shortness of breath that occur at night, often waking individuals from sleep. This symptom is a significant manifestation of heart failure and is closely linked to fluid accumulation in the lungs when the person lies flat. As the fluid redistributes due to gravity, particularly in individuals with compromised cardiac function, it can lead to acute breathlessness, causing the individual to awaken, sometimes gasping for air.

The sense of extreme breathlessness experienced during PND can be distressing and is a defining feature of this condition. It is important for healthcare providers to recognize this symptom, as it can indicate worsening heart failure or fluid overload and may prompt timely intervention.

Chest pain, extreme fatigue, and persistent cough can be associated with various cardiac or pulmonary conditions, but they do not specifically represent the hallmark feature of paroxysmal nocturnal dyspnea. Hence, the correct choice highlights the defining nature of breathlessness in this context.