From the Guidelines
Positive orthostatic vital signs are characterized by a significant drop in blood pressure or increase in heart rate when a person changes position from lying down to sitting or standing, with orthostatic hypotension diagnosed when there's a decrease in systolic blood pressure of at least 20 mmHg or a decrease in diastolic blood pressure of at least 10 mmHg within three minutes of standing, as defined by the European Heart Journal in 2018 1. These changes occur because when a person stands up, blood pools in the lower extremities due to gravity, and normally the body compensates by constricting blood vessels and increasing heart rate. When this compensatory mechanism fails, orthostatic changes occur. Some key points to consider include:
- Orthostatic hypotension can be classified into different types, including initial, classical, and delayed orthostatic hypotension, each with distinct characteristics and time frames for onset after standing, as outlined in the 2018 European Heart Journal guidelines 1.
- The diagnosis of orthostatic hypotension is based on a sustained decrease in systolic blood pressure of at least 20 mmHg, diastolic blood pressure of at least 10 mmHg, or a sustained decrease in systolic blood pressure to an absolute value less than 90 mmHg within three minutes of active standing or head-up tilt of at least 60 degrees, as specified in the 2018 European Heart Journal guidelines 1.
- Common causes of orthostatic hypotension include dehydration, blood loss, certain medications, autonomic nervous system disorders, prolonged bed rest, and aging, as discussed in the 2017 American College of Cardiology guidelines 1.
- Symptoms of orthostatic hypotension may include lightheadedness, dizziness, blurred vision, weakness, fatigue, or syncope upon standing, as described in the 2017 American College of Cardiology guidelines 1.
- The 2019 Journal of the American College of Cardiology comparison of guidelines highlights the importance of considering the definitions and diagnostic criteria for orthostatic hypotension and other related conditions, such as postural orthostatic tachycardia syndrome (POTS), in clinical practice, as outlined in the comparison of ACC/AHA/HRS and ESC guidelines 1.
From the Research
Definition of Positive Orthostatic Vital Signs
- Positive orthostatic vital signs are not explicitly defined in the provided studies, but orthostatic vital signs (OVS) are mentioned as a diagnostic tool to assess hypovolemia and other conditions 2.
- OVS are measured by taking vital signs in both supine and standing positions, and a significant change in blood pressure or heart rate between the two positions may indicate orthostatic hypotension or other conditions.
Indications for Orthostatic Vital Signs
- OVS are useful in selected patients with frequent ED presentations, such as blood loss, dehydration, dizziness, weakness, and falls 2.
- They are also used to diagnose and manage orthostatic hypotension, a condition characterized by a significant drop in blood pressure when standing up from a sitting or lying down position 3, 4, 5, 6.
Interpretation of Orthostatic Vital Signs
- The interpretation of OVS is subject to physician interpretation, and the criteria for a positive test are controversial 2.
- A significant drop in systolic blood pressure (≥20 mmHg) or diastolic blood pressure (≥10 mmHg) when standing up from a sitting or lying down position may indicate orthostatic hypotension 4.
- Other symptoms, such as dizziness, lightheadedness, and syncope, may also be considered when interpreting OVS 5, 6.