1. Central Venous Pressure and Central lines
Big Lines for Big Problems

2. Challenging Knowledge
Before starting this module; Answer the following questions
What sites are used to site a CVL?
What is the normal CVP?
What are the basic treatments for a CVP of -1cm of H20
What are the essential items required to measure a CVP?

3. Learning Outcomes By the end of this module you should
Be aware of factors which affect the CVP
Recognise normal and abnormal CVP values
Be able to set up the manometer system to measure a patient’s CVP
Be able to measure a CVP and interpret the value
Be aware of the initial management for high and low values

4. Factors affecting the CVP
The central venous pressure reflects the right atrial pressure (RAP) and is similar to measuring the JVP clinically
The factors which affect the CVP are:-
Systemic vasodilatation and hypovolaemia, which leads to reduced venous return in the vena cava and reduced RAP
Right ventricular failure
Tricuspid and Pulmonary valve disease
Pulmonary hypertension
Right ventricular dysfunction and pulmonary hypertension leads to raised right atrial pressure, as does tricuspid and pulmonary stenosis.

5. Central venous line (CVL)
Indications for CVL
Severe hypovolaemia requiring rapid infusion
(although initial resuscitation may be peripheral through wide bore cannulae)
Infusion of drugs which may cause peripheral problems e.g. vasoconstriction, phlebitis
Measurement of central venous pressure (CVP)
Confirmation of diagnosis e.g. Right heart failure
Insertion of a pacing wire.
Sites for insertion – Internal jugular, subclavian and femoral vein; ‘Long lines’ are also inserted in the brachial vein.

6. How to measure the CVP using a manometer system
The CVP system
A bag of saline or dextrose = ‘reservoir’
Three way tap - connected to manometer, reservoir and patient’s CVL by tubing; System is primed with fluid before starting
Patient is lying supine if possible
Manometer has spirit level at ‘zero’; Zero point is aligned with right atrium using the mid axillary line / 4th ICS
Measurements should be taken with the patient in the same position each time using the spirit level; the zero point on the skin surface is marked for consistency of measurement
Patient positionedsupine on the bed
Three way tap

7. How to measure the CVP using a manometer system
Turn the three way tap OFF to the patient.
Fill the manometer to the top from the reservoir
Turn the three way tap OFF to the reservoir
This means the column of fluid is supported only by the RAP / CV pressure
The column will fall according to CVP
The column swings with respiration - conventionally the level is taken as the mean.
Three way tap OFF to the patient – allowing the manometer to be filled
Three way tap OFF to the reservoir – allowing the CVP to be measured

8. Normal CVP measurements
The normal CVP is between 5 – 10 cm of H2O (it increases 3 – 5 cm H2O when patient is being ventilated)
In high dependency areas an electronic transducer is connected instead of the manometer system. This gives a continuous readout of CVP along with a display of the waveform. This may be measured in mmHg.
(Note:10 cmH20 = 7.5mmHg =1kPa)

9. Other clinical features Diagnosis Treatment
CVP Reading
Other clinical features
Diagnosis
Treatment
Low
Tachycardia
Low normal or hypotension
Urine output – oligo or anuria
Hypovolaemia
Fluid challenge until CVP within normal limits and treat underlying cause
( may be normal or high due to venoconstriction)
Signs of infection Pyrexia Vasodilatation is most common but severe sepsis maybe associated with constriction
Sepsis
Fluid resuscitation (if low)
Antibiotics
May require inotrope support
Normal – due to venoconstriction
Urine output ‘falling’ below 30ml /hr
Poor capillary refill
Fluid challenge and treat underlying cause
High
Dyspnoea with pulmonary crepitations
Tachycardia with third heart sound Tender hepatomegaly
Ascites
Peripheral Oedema
Heart failure
Diuretics, GTN infusion, may require inotropes
Very High
Venous congestion and dilatation of face and neck; associated signs
SVC obstruction
Cardiac tamponade
Tension pneumothorax
Treat underlying cause

10. Case (1) – How low can you go?
A 32 year old woman with known alcohol associated liver disease presents with melaena. Initially she is haemodynamically stable and well perfused. She suddenly decompensates with fresh blood and clots being passed PR. Initial resuscitation with several litres of crystalloid and some colloid fails to bring her systolic BP back above 100 mm Hg. A CVP line is inserted and shows her CVP to be +1 cmH2O.
(a) What is the likely diagnosis?
(b) List your further management – including investigations and medications

11. Case (2) – CVP ‘Pat pending’
A 31 year old man presents to A&E with a 3 month history of night sweats and weight loss. On examination he is unwell, pyrexial and has several large cervical lymph nodes. He is noted to have poorly palpable radial pulse, a positive Kussmaul’s sign and poorly heard heart sounds. The SHO decides to site a CVP which is measured at 28 cm of H2O.
(a) What is the likely underlying diagnosis?
(b) What is the initial treatment?
(c) How will you prove the diagnosis?

12. Case (3)
A 48 year old poorly controlled Type 2 diabetic man is admitted from the Diabetes clinic with a deep, infected foot ulcer. His observations are: pulse 120bpm, BP 70/40, CVP +6 cm of H20 and he is noted to be ‘sweaty and vasodilated’. Despite initial resuscitation with 3 litres of crystalloid in 4 hours, his BP and pulse fail to respond. He is electively ventilated and admitted to ITU where he is started on inotropes.
What is the descriptive term given to this clinical state?
List your further management?

13. Learning Outcomes At the end of this module you should
Be aware of the factors affecting the CVP.
Be able to set up a CVP manometer system.
Be able to measure a CVP from a patient.
Be able to interpret the result.
Be able to institute initial management based on the result.