CENTRAL VENOUS PRESSURE – Objectives, Indications, Indication of Lowered CVP, Indication of Increased CVP, Site for Catheter Placement, General Instructions, Preliminary Assessment, Preparation of the Patient and Environment, Equipment, Procedure, Measurement Concept Validation Plan (MCVP) Measurement, Interpretation of CVP, False CVP, Post-Procedure Care and Complications (NURSING PROCEDURE)
Central venous pressure (CVP) is the pressure within the superior vena cava, reflecting the pressure under which the blood is returned to the superior vena cava and right atrium
Central venous pressure is determined by vascular tone, blood volume, and the ability of the right heart to receive and pump blood
Central venous pressure is one of the hemodynamic measurement techniques used to measure the pressure in the right atrium or within the vena cava
Central venous pressure is a dynamic or changing measurement. The change in CVP correlated with patient’s clinical status
OBJECTIVES
- To evaluate the adequacy of circulating blood volume and assess the degree of hypovolemia, e.g. in shock
- To provide access to central veins for fluid replacement in case of emergency
- To administer high caloric fluid diet intravenously in certain chronic hypercatabolic states, e.g. burns (intravenous hyperalimentation)
- To serve as a guide in fluid replacement in seriously ill patients
- To administer long-term chemotherapy
INDICATIONS
- Central venous pressure reflects right ventricular failure. Most right ventricular failure is secondary to left ventricular failure
- Central venous pressure is a more useful indication of adequacy of venous blood volume and alternations of cardiovascular function
- Cardiothoracic surgery
- Management of patient in shock in ICU
- Transplant surgery
- Normal CVP: 2-12 cm H2O
INDICATION OF LOWERED CVP
- Early left ventricular failure
- Decreased circulating volume
- Vasodilation/peripheral pooling
- Septic shock
INDICATION OF INCREASED CVP
- Valvular stenosis
- Pulmonary hypertension
- Increased circulating volume
- Vasoconstriction
- Hypertension
SITE FOR CATHETER PLACEMENT
- Subclavian vein
- Internal or external jugular veins
- Median basilic vein
GENERAL INSTRUCTIONS
- Do not give head down tilt to a patient of impending cardiac failure
- Before introducing bigger catheter, incise skin with a No. 15 blade
- Catheter, from which free blood cannot be aspirated, should not be left in the skin
- CVP catheter should be taken to prevent blocking by continuous flush drip with low flow rates
- Dressing over puncture site should be changed on alternative days, with aseptic precautions
- Periodic blood samples should be taken for culture
PRELIMINARY ASSESSMENT
Check
- The doctor’s order for specific instructions
- Check the assembly of the catheter
- General condition and diagnosis of the patient
- Mental status to follow instructions
- Articles available in the unit
PREPARATION OF THE PATIENT AND ENVIRONMENT
- The procedure should be explained to the patient
- The CVP site should be prepared by shaving and cleansing with an antiseptic solution
- Measure the length of the manometer
- Ensure that the facilitates for cardiopulmonary resuscitation, intercostals drain and X-ray of the chest are available
- Measure the length of catheter required from anatomical puncture point to superior vena cava
- Assemble articles required for the procedure
- Place the patient in a comfortable position. This is the baseline position used for subsequent reading
EQUIPMENT
- Venous pressure apparatus with water manometer
- Cut down tray with intravenous catheter
- Infusion solution and infusion catheter
- Three way stop clock
- IV pole attached to bed arm board and adhesive tape
- Carpenter’s level (for establishing zero point)
- ECG monitors
PROCEDURE
- Attach the manometer to the IV pole with the zero point of the manometer on the level with the patient’s right
- Mark the midaxillary line on the patient which is the reference point for subsequent reading
- The intravenous catheter (about 24 inches long, size 14 or 16 gauge) is passed through the median basilica, subclavian or jugular vein
- CVP catheter is connected to a 3 way stopcock which communicates with the manometer and an open IV system
- Catheter is secured by a suture to prevent accidental removal and apply dressing
MEASUREMENT CONCEPT VALIDATION PLAN (MCVP) MEASUREMENT
- Always adjust the position of the patient to the position used for first reading
- Position the zero point on the manometer with the level of the atrium
- Turn the stopcock so that the IV solution flows into the manometer filling 20 to 25 cm level
- Turn the stopcock again so that the solution in the manometer flows into the patient
- Observe the fall of height of the column of fluid in the manometer. Record the level at which the stabilizes
- Turn the stopcock against to allow the IV solution to flow from the container to the patient’s vein by a slow drip
INTERPRETATION OF CVP
- Normal CVP value ranging from 2 cm to 14 cm of H2O
- Low BP and low CVP hypovolemia
- High or normal BP and high CVP – over transfusion
- Low BP and high CVP – cardiac dysfunction
FALSE CVP
Before any measurement of CVP is taken as fine, chances of false high or low reading should be kept in mind and ruled out
Causes of False High CVP
- Leakage in the system
- Wrong zero reference point
POST-PROCEDURAL CARE
To prevent chances of infection when CVP catheter is kept for a long time in a critically ill patient, special care should be taken such as:
- Dressing over puncture site should be changed on alternate days, with aseptic precautions
- Changing of dressing in ward should be done with aseptic precautions
- Infusion set should be changed daily
- Periodic blood samples should be taken for culture
COMPLICATIONS
- Pneumothorax: commonly occurs with subclavian cannulation. It accounts for 30% of reported complications. Incidence can be reduced by correct placement.
- Air embolism: in hypovolemic tachypneic patient and crying babies, potential for rapid air entry should not be underestimated. To prevent this always expel the air from the tubing before connecting them into the vein. All connections should be secured to prevent accidental dislodging of the tube and entry of air into the veins
- Clot formation: the CVP line should always be connected to an IV infusion to prevent clot formation in the intravenous catheter
- Infection: use strict aseptic techniques when preparing the tubing and/or when changing the tubing. Inspect the catheter insertion site daily for pain, swelling or exudates
- Arrhythmias: maintain ECG monitoring to detect any arrhythmias caused by the passage of catheter into the right ventricle. A chest X-ray may be taken to check the position of the catheter in the right atrium
- Fluid overload: carefully monitor the CVP reading. Watch for other signs of fluid overload such as pulmonary edema, respiratory distress, frothy sputum, etc
