CENTRAL VENOUS PRESSURE

LEARNING OUTCOMES By the end of this session the student should be able to : Explain the indications for a patient requiring CVP monitoring Identify the equipment required for commencing CVP monitoring Describe the nursing role, both in the care and use of the central venous monitoring line Discuss the reasons for abnormal CVP readings.

CENTRAL VENOUS PRESSURE DEFINITION Blood from the systemic veins flows into the right atrium. The pressure in the right atrium is the CVP. A catheter is passed via; the subclavian vein or jugular vein into the superior vena cava to determine the venous return and intravascular volume of the right atrium. The normal value is 6-12cm H 2 O

CENTRAL VENOUS PRESSURE PURPOSE To serve as a guide of fluid balance in critically ill patients (To guide the administration of fluid or diuretics.) To estimate the circulating blood volume To determine the function of the right side of the heart To assist in monitoring circulatory failure None of these variables are measured directly; they must be interpreted.

CENTRAL VENOUS PRESSURE Axillary vein Cephalic vein Median cubital vein Basilic vein ACCESS External Jugular vein Subclavian vein

CENTRAL VENOUS PRESSURE COMPLICATIONS Carotid Artery Puncture Pneumothorax Air Embolism Arrhythmia Perforation of SVC or R. Atrium/Ventricle Infection Pleural Effusion Extravasion Allergic reaction to catheter material

CENTRAL VENOUS PRESSURE EQUIPMENT The equipment needed for measurement of central venous pressure includes a sterile bag of fluids (a) with attached fluid administration set (b), an IV extension set (c), a manometer (d) and a stopcock (e). a. b. c. d. e.

CENTRAL VENOUS PRESSURE EQUIPMENT IV extension set to entry port of patients central line. IV giving set to fluid bag. Stopcock (Three way tap)

CENTRAL VENOUS PRESSURE -Patient Preparation: *Place the patient in the supine position with the head of the bed flat. *Locate and mark the phlebostatic axis with the skin marker.

CENTRAL VENOUS PRESSURE DIRECTION OF FLOW -The white arrows indicate the direction of fluid flow. -Initially the white knob is turned straight up towards the manometer, allowing fluid to flow from the fluid bag to the patient's catheter to assure the catheter is patent (a). -If fluid does not flow freely into the patient's catheter a valid CVP reading will not be obtained. a. c.b.

CENTRAL VENOUS PRESSURE -Then the knob is turned toward the patient (b) and fluid will fill the manometer. -The manometer should not contain any air bubbles. -If air is present in the manometer or fluid line, let the fluids run, overfilling the manometer until all air is purged from the system.

CENTRAL VENOUS PRESSURE -Then turn the knob toward the fluids (c). -The level of fluid in the manometer will fall (the fluid is running into the patient's catheter) until the height of the fluid column exerts a pressure equivalent to the patient's central venous pressure. -The top of the fluid column will slightly oscillate up and down.

CENTRAL VENOUS PRESSURE n n -Take the CVP reading when the fluid level stabilizes at the end of expiration. n n -Turn the stopcock off to the manometer and run the IV fluids through the central venous line as prescribed. n n Post care: n n Patient: Return the patient to correct position. n n Nurse: Handwash. n n Environment: Return equipment. n n Documentation: Document the reading.

CENTRAL VENOUS PRESSURE POSITION OF PATIENT 3-way tap manometer Fluid Bag Patient in supine position Central Venous Access phlebostatic axis

CENTRAL VENOUS PRESSURE INTERPRETATION An increase of above normal may indicate weakening or failure of the right side of the heart, or excessive intravascular volume A pressure below 5cm H 2 O usually reflects an intravascular volume deficit or drug induced excessive vasodilation CVP measurements must not be interpreted on their own, but viewed alongside the patient's full clinical picture (BP, Respiratory Pattern, Colour, Temperature) Several measurements are required to identify a trend

CENTRAL VENOUS PRESSURE DETERMINANTS Cardiac Competence (reduced ventricular function raises CVP) Blood Volume (increased venous return raises CVP) Intra Aortic & Intra Peritoneal Pressure (raises CVP) Systemic Vascular Resistance (raises CVP) CVP

CENTRAL VENOUS PRESSURE REFERENCES Henderson N., (1997)Central Venous Lines Nursing Standard 11:42, pp49-56 Mallett J.,(2000)The Royal Marsden NHS Trust Dougherty L.,Manual of Clinical Nursing Procedures, Fifth Edition Oxford; Blackwell Science, pp Mc Dermott M.,(1995)Central Venous Pressure Nursing Standard 9:35, pp54 Nursing Standard., (1999)Quick Reference Guide 6. Central Venous Lines Nursing Standard 13:42.

CENTRAL VENOUS PRESSURE