Central venous pressure

Measuring stick for determining the ZVD via the hydrostatic pressure

Central venous pressure or central venous pressure ( CVP ) is the blood pressure in front of the right atrium of the heart in the superior vena cava (superior vena cava). The central part in the term refers to the valveless space in the center of the bloodstream (especially in front of or in the right atrium) on the heart. Diagnostic conclusions can be drawn from the measurement of the central venous pressure, particularly with continuous registration. The central venous pressure is measured using a central venous catheter .

meaning

The central venous pressure has long been used as a correlate for the intravascular volume, i.e. the amount of blood and fluid that is inside the vessels , which is now largely obsolete . Numerous studies have shown that the connection with the intravascular volume status is very low. The ZVD can be used as an indicator for the preload .

About the central venous catheter and the central venous can be oxygen saturation determined. Under a number of conditions, including a. that the arterial oxygen saturation is normal, the patient has no oxygen utilization disorder (as can be the case, for example, with sepsis ) and no arteriovenous shunt is present, it can be used as an indication of sufficient cardiac output . Determining the mixed venous saturation with the help of a pulmonary artery catheter has the advantage that the blood comes from the upper and lower halves of the body (therefore mixed venous).

Indications

The measurement of the central venous pressure is indicated at

Operations with greater fluid displacement or blood loss
Hypovolemia (decreased blood or plasma amount in the circulation)
shock
seriously injured patients (with multiple trauma )

Measurement

The CVP is measured invasively via the central venous catheter (CVC) on the patient lying flat. It can be determined with an electronic manometer or as the height of a column of liquid above the zero point determined by means of a thorax caliper . The zero point is about 2/5 of the thorax height below the breastbone . The permanent measurement of the CVP can be carried out just like the direct blood pressure measurement (IBP) via a monitor . Instead of the arterial catheter, the CVC is connected to a pressure sensor.

The plausibility of the CVP measurement can be assessed in an ultrasound examination based on the width of the inferior vena cava .

Normal values

The central venous pressure is given in mmHg .

0-9 mmHg; this corresponds to 0–12 cm water column [cmH ₂ O] (conversion factor: 1 mmHg ≈ 1.36 cmH ₂ O)
SI -conform: 0-1.199 kPa (conversion factor: 1 mmHg ≈ 133.3 Pa)

ZVD curve progression

Relationship between ECG and CVP waveforms (below) on a medical surveillance monitor. Heart rate: 70 / min, CVP: 9 mmHg. The waves that run synchronously with the heart's action are marked on the ZVD curve.

In addition to measuring the CVP as a mean value, the CVT can also be displayed as a curve. The following ACXVY process occurs in healthy people:

A wave: contraction of the right atrium ( a trium)
C wave: Closure ( C losure) and bulging of the tricuspid valve into the atrium
X -sink: Real x ation (complete relaxation) of the court
V -wave: v enöser influx into the atrium by moving the heart valve plane direction of the heart base
Y- depression: opening of the tricuspid valve and outflow of blood into the right ventricle

In the case of diseases, the CVP curve changes depending on the changed pressure and flow conditions:

no A waves: atrial fibrillation , sinus tachycardia
high A waves: pulmonary hypertension , tricuspid valve stenosis ,
very high A waves = cannon waves: pumping of the atrium against closed tricuspid valve such as B. in third degree AV block
high V-waves: tricuspid valve regurgitation with blood flowing back during the atrial filling
Fusion of V and C waves: tricuspid valve regurgitation due to the absence of the X wave

Deviations

The CVP can be reduced in acute or chronic volume deficiency. It can be increased in the case of right heart failure , high positive end-expiratory pressure (PEEP) in the context of controlled ventilation , overhydration , cardiac tamponade or pulmonary embolism .

Possible errors

The catheter rests against the vessel wall; then the ZVD is incorrectly measured too high.
The zero point is set incorrectly.
The patient is not lying exactly level.
There are air bubbles in the measuring system or in the transducer .
The measuring system hose is squeezed.
Changes in intrathoracic pressure
- during ventilation
- if the patient presses during the measurement (with stomach or chest)
The infusion line is open and liquid runs over the system during the measurement.

literature

Reinhard Larsen: Anesthesia and intensive medicine in cardiac, thoracic and vascular surgery. (1st edition 1986) 5th edition. Springer, Berlin / Heidelberg / New York et al. 1999, ISBN 3-540-65024-5 , pp. 127-129.
Reinhard Larsen: anesthesia. 8th (7th revised and expanded) edition. Urban & Fischer, Munich / Jena 2002, ISBN 3-437-22500-6 , pp. 668-670.

Web links

Specialized care knowledge - e.g. Venous pressure

Individual evidence

↑ PE Marik, M. Baram, B. Vahid: Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest. 2008 Jul; 134 (1): 172-8. Review. PMID 18628220
↑ ^a ^b ^c ^d Lothar Ullrich, Dietmar Stolecki, Matthias Grünewald: Intensive care and anesthesia . Thieme Verlag, Stuttgart 2010, ISBN 978-3-13-152942-8 , p. 184 f . ( limited preview in Google Book search).
↑ Theodor Baars, Raimund Erbel : Internal intensive care and emergency medicine: algorithm-based practical knowledge . Deutscher Ärzte-Verlag , Cologne 2011, ISBN 978-3-7691-1282-5 , p. 64 ( limited preview in Google Book search).
^ Hans Walter Striebel: Operative Intensive Care Medicine: Safety in Clinical Practice . Schattauer, Stuttgart 2015, ISBN 978-3-7945-2895-0 , pp. 223, 225 .
^ Franz Kehl: Anesthesia questions and answers 1655 facts for the specialist examination and the European diploma for anesthesiology and intensive medicine (DESA) . Springer, Berlin 2013, ISBN 3-642-35034-8 .

[1] PE Marik, M. Baram, B. Vahid: Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest. 2008 Jul; 134 (1): 172-8. Review. PMID 18628220

[Ull-2] Lothar Ullrich, Dietmar Stolecki, Matthias Grünewald: Intensive care and anesthesia . Thieme Verlag, Stuttgart 2010, ISBN 978-3-13-152942-8 , p. 184 f . ( limited preview in Google Book search).

[3] Theodor Baars, Raimund Erbel : Internal intensive care and emergency medicine: algorithm-based practical knowledge . Deutscher Ärzte-Verlag , Cologne 2011, ISBN 978-3-7691-1282-5 , p. 64 ( limited preview in Google Book search).

[4] Hans Walter Striebel: Operative Intensive Care Medicine: Safety in Clinical Practice . Schattauer, Stuttgart 2015, ISBN 978-3-7945-2895-0 , pp. 223, 225 .

[Kehl_2013_p.-5] Franz Kehl: Anesthesia questions and answers 1655 facts for the specialist examination and the European diploma for anesthesiology and intensive medicine (DESA) . Springer, Berlin 2013, ISBN 3-642-35034-8 .