Central venous pressure

Central venous pressure (CVP), also known as mean venous pressure (MVP) is the pressure of blood in the thoracic vena cava, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system. CVP is often a good approximation of right atrial pressure (RAP),^[1] however the two terms are not identical, as right atrial pressure is the pressure in the right atrium. CVP and RAP can differ when arterial tone is altered. This can be graphically depicted as changes in the slope of the venous return plotted against right atrial pressure (where central venous pressure increases, but right atrial pressure stays the same; VR = CVP-RAP).

CVP has been, and often still is, used as a surrogate for preload, and changes in CVP in response to infusions of intravenous fluid have been used to predict volume-responsiveness (i.e. whether more fluid will improve cardiac output). However, there is increasing evidence that CVP, whether as an absolute value or in terms of changes in response to fluid, does not correlate with ventricular volume (i.e. preload) or volume-responsiveness, and so should not be used to guide intravenous fluid therapy.^[2]^[3] Nevertheless, CVP monitoring is a useful tool to guide hemodynamic therapy. The cardiopulmonary baroreflex responds to an increase in CVP by decreasing total peripheral resistance while increasing HR and ventricular contractility in dogs.^[4]

Measurement 1
Factors affecting CVP 2
See also 3
References 4
External links 5

Measurement

Site		Normal pressure range (in mmHg)^[5]
Central venous pressure		3–8
Right ventricular pressure	systolic	15–30
Right ventricular pressure	diastolic	3–8
Pulmonary artery pressure	systolic	15–30
Pulmonary artery pressure	diastolic	4–12
Pulmonary vein/ Pulmonary capillary wedge pressure		2–15
Left ventricular pressure	systolic	100–140
Left ventricular pressure	diastolic	3-12

Normal CVP can be measured from two points of reference:

Sternum: 0–14 cm H₂O
Midaxillary line: 8–15 cm H₂O

CVP can be measured by connecting the patient's central venous catheter to a special infusion set which is connected to a small diameter water column. If the water column is calibrated properly the height of the column indicates the CVP.

In most intensive care units, facilities are available to measure CVP continuously.

Normal values vary between 5 and 10 cmH₂0 ^[6]

Factors affecting CVP

Factors that increase CVP include:

Hypervolemia
forced exhalation
Tension pneumothorax
Heart failure
Pleural effusion
Decreased cardiac output
Cardiac tamponade
Mechanical ventilation and the application of positive end-expiratory pressure (PEEP)
Pulmonary Hypertension
Pulmonary Embolism

Factors that decrease CVP include:

References

^ "Central Venous Catheter Physiology". Retrieved 2009-02-27.
^ Kumar A, Anel R, Bunnell E, Habet K, Zanotti S, Marshall S; et al. (2004). "Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects" (PDF). Crit Care Med 32 (3).
^ Marik P, Baram M, Vahid B (July 2008). "Does Central Venous Pressure Predict Fluid Responsiveness?" (PDF). Chest 134 (1).
^ Sala-Mercado JA, Moslehpour M, Hammond RL, Ichinose M, Chen X, Evan S, O'Leary DS, Mukkamala R (June 2014). "Stimulation of the Cardiopulmonary Baroreflex Enhances Ventricular Contractility in Awake Dogs: A Mathematical Analysis Study". American Journal of Physiology - Regulatory, Integrative and Comparative Physiology 307 (4): R455–R464.
^ Table 30-1 in: Trudie A Goers; Washington University School of Medicine Department of Surgery; Klingensmith, Mary E; Li Ern Chen; Sean C Glasgow (2008). The Washington manual of surgery. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins.
^ Egan's Fundamentals of Respiratory Care 9th ed, p. 1140

External links

Venous function and central venous pressure: a physiologic story - a technical discussion of the more modern understanding of central venous pressure; this may well conflict with the sources below.
Central Venous Pressure Monitoring
Cardiovascular Physiology Concepts
Central Venous Pressure and Pulmonary Capillary Wedge Monitoring
Cardiovascular Physiology
Central Venous Pressure at the US National Library of Medicine Medical Subject Headings (MeSH)

Physiology of the cardiovascular system

Heart

Cardiac output	Cardiac cycle Cardiac output Heart rate Stroke volume Stroke volume End-diastolic volume End-systolic volume Afterload Preload Frank–Starling law of the heart Cardiac function curve Venous return curve Wiggers diagram Pressure volume diagram

Ultrasound	Fractional shortening = (End-diastolic dimension End-systolic dimension) / End-diastolic dimension Aortic valve area calculation Ejection fraction Cardiac index

Heart rate	Cardiac pacemaker Chronotropic (Heart rate) Dromotropic (Conduction velocity) Inotropic (Contractility) Bathmotropic (Excitability) Lusitropic (Relaxation)

Conduction	Conduction system Cardiac electrophysiology Action potential cardiac atrial ventricular Effective refractory period Pacemaker potential Electrocardiography P wave PR interval QRS complex QT interval ST segment T wave U wave Hexaxial reference system

Chamber pressure	Central venous Right atrial ventricular pulmonary artery wedge Left atrial ventricular Aortic

Other	Ventricular remodeling

Vascular system/
Hemodynamics

Blood flow	Compliance Vascular resistance Pulse Perfusion

Blood pressure	Pulse pressure Systolic Diastolic Mean arterial pressure Jugular venous pressure Portal venous pressure

Regulation of BP	Baroreflex Kinin–kallikrein system Renin–angiotensin system Vasoconstrictors Vasodilators Autoregulation Myogenic mechanism Tubuloglomerular feedback Cerebral autoregulation Paraganglia Aortic body Carotid body Glomus cell

Index of the heart

Description

Disease

Treatment	Drugs

Index of the circulatory system

Description	Arteries Veins

Disease

Treatment	Drugs

Central venous pressure