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Central venous pressure measurement

Central venous pressure refers to the pressure of the superior vena cava or inferior vena cava. To a certain extent, the central vein reflects the patient's comprehensive conditions such as effective blood volume, cardiac function, and vascular tone at the time of pressure measurement. Therefore, continuous measurement of changes in central venous pressure can dynamically understand changes in blood volume and determine the heart's ability to tolerate rehydration. It is an important reference indicator for adjusting infusion therapy.

Normal value

0.59～1.18kPa. (6-12cmH2O)

Clinical significance

An increase indicates clear cardiac insufficiency and the risk of pulmonary edema.

Reducing the effective return blood volume is insufficient.

Possible diseases with low results:

Iliac vein compression syndrome, neonatal shock, pediatric shock, phlebitis, heart failure, and prerenal renal failure.

Possible diseases with high results:

Sepsis, penetrating cardiac injury, penetrating cardiac trauma, and air embolism.

Notes

1. Strict sterility must be observed during operation.

2. The zero point of the pressure measuring tube must be on the same plane as the middle part of the right atrium. The zero point should be recalibrated after body position changes.

3. The catheter should be kept unobstructed, otherwise it will affect the pressure measurement results.

4. The length of time the central venous catheter is retained is closely related to the incidence of infection. The catheter should be removed as soon as the condition permits. Usually the central venous catheter is placed for about one week. If it is still needed, a new catheter can be placed in another location.

5. During hypotension, if the central venous pressure is <0.49kPa (5cmH20), it indicates that the effective blood volume is insufficient. Rapid fluid or plasma can be replenished to increase the central venous pressure to 0.59~l.l8kPa (6 ~12cmH2O), if there is hypotension but the central venous pressure is higher than 1.18kPa (l2cmH2O), the possibility of cardiac dysfunction should be considered. Drugs that increase myocardial contractility can be used, such as dopamine, dobutamine, etc., and the dosage should be controlled. Central venous pressure higher than 1.47~1.96kPa (15~2OcmH2O) indicates obvious right ventricular insufficiency and the possibility of pulmonary edema. Rapid diuretics and digitalis drugs are required. In addition, low central venous pressure can also be seen in states of vasodilation caused by sepsis, hyperthermia, etc. It must be pointed out that the significance of evaluating central venous pressure should be considered from three aspects: blood volume, cardiac function and vascular status. When blood volume is insufficient and cardiac function is insufficient, central venous pressure may be normal, so clinical judgment is required and comprehensive judgment is required.

Inspection process

1. Pass the sterile plastic tube through the deep venipuncture method and pass it through the peripheral vein (usually the subclavian vein, the junction of the subclavian vein and the internal jugular vein or the femoral vein). vein, etc.) into the superior vena cava or inferior vena cava near the right atrium.

2. Before intubation, a three-way valve should be connected in advance and connected to the infusion set for continuous infusion.

3. The "L" shaped pressure measuring tube is fixed on the wooden board and connected to the three-way valve. When measuring pressure, turn the three-way valve to first raise the water column in the pressure measuring tube, then connect the conduit to the pressure measuring tube to block the connection with the infusion set. When the water column in the pressure measuring tube stops falling, it is the measured central venous pressure value. After the measurement, close the pressure measuring tube and connect it to the infusion set to continue infusion.

4. No matter what position the patient takes, the pressure is measured at the level of the right atrium. That is, the "0" point of the pressure measuring tube must be at the same level as the right atrium. The patient should be at the same level as the mid-axillary line when lying supine.

5. To prevent coagulation in the tube, a small amount of anticoagulant should be added to the instilled liquid (2.5 to 5 mg of heparin per 500 ml of liquid), or 3.8% sodium citrate should be injected into the pressure measuring tube. .

Unsuitable groups

1. Skin infection at the intended puncture site.

2. Those with severe coagulation dysfunction or receiving anticoagulant therapy.

3. Bacteremia or sepsis.

4. Those who are allergic to local anesthetics or specific materials.

5. Yu Tong performed right heart catheterization.

Adverse reactions and risks: May cause infection.