CVP is elevated in all the following conditions; EXCEPT:

Appeared in: Combined AIIMS - 2020 (Jodhpur, Bhopal, Patna, Raipur)

Explanation

Hypovolemic shock is defined by a critical reduction in the effective circulating blood volume.
This loss of volume leads to decreased venous return to the right side of the heart, a state known as reduced preload.
A reduction in preload directly causes a decrease in the pressure within the central veins and right atrium, which is measured as a low Central Venous Pressure (CVP).
Therefore, hypovolemic shock is the exception among the given options, as it is associated with a low CVP, not an elevated one.

Option B: Overhydration, or hypervolemia, means there is an excess of fluid in the circulatory system. This increased volume directly raises the pressure within the venous system, leading to an elevated CVP.
Option C: In heart failure, especially right-sided heart failure, the ventricle cannot effectively pump blood forward. This causes blood to back up into the systemic venous circulation, resulting in venous congestion and an elevated CVP.
Option D: Positive pressure breathing, such as with mechanical ventilation, increases the pressure inside the thoracic cavity. This intrathoracic pressure is transmitted to the great vessels and the heart, causing a falsely elevated CVP measurement.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Central Venous Pressure (CVP) and factors affecting it as background academic context rather than a clinical decision trigger.
CVP monitoring is a cornerstone of hemodynamic assessment in critically ill patients, providing vital information about fluid status and right heart function.
A low CVP (less than 2-6 mmHg) in a hypotensive patient is a strong indicator of hypovolemia, guiding the nurse to administer fluid resuscitation as prescribed.
A high CVP (greater than 8-12 mmHg) can signal fluid overload, heart failure, or pulmonary hypertension, prompting interventions like diuretic administration or the use of inotropes.

How to Approach the Question

First, identify the keyword 'EXCEPT' in the question stem. This signals that you must find the option that is the outlier or does not belong with the others.
Next, recall the definition of Central Venous Pressure (CVP). It is a measure of the pressure in the right atrium and vena cava, reflecting right ventricular preload and fluid volume status.
Analyze each option's physiological effect on blood volume and pressure within the central venous system.
Evaluate Option A (Hypovolemic shock): 'Hypo-' means low, 'vol-' means volume. Low volume leads to low pressure. This decreases CVP.
Evaluate Option B (Overhydration): 'Over-' means excess. Excess fluid volume increases pressure. This increases CVP.
Evaluate Option C (Heart failure): A failing heart pump causes blood to back up in the venous system, increasing pressure. This increases CVP.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 198-200

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 391-393

Practise the full Combined AIIMS - 2020 (Jodhpur, Bhopal, Patna, Raipur)

Attempt every question from this paper in a timed mock, then review the full solution for each one.