Dr. Subrata Kumar
University Cardiac Center
What is CVP ?
The central venous pressure (CVP) is the pressure
measured in the central veins close to the heart.
It indicates mean right atrial pressure and is
frequently used as an estimate of right ventricular
CVP reflects the amount of blood returning to the
heart and the ability of the heart to pump the
blood into the arterial system.
It is the pressure measured at the junction of the
superior vena cava and the right atrium.
It reflects the driving force for filling of the right
atrium & ventricle.
It indicates the relationship of blood volume to
the capacity of the venous system.
Normal CVP in an awake , spontaneously
breathing patient : 1-7 mmHg or
5-10 cm H2O.
Mechanical ventilation : 3-5 cm H2O higher.
CENTRAL VENOUS PRESSURE
In central venous pressure monitoring, the physician
inserts a catheter through a vein and advances it
until its tip lies in or near the right atrium.
Because no major valves lie at the junction of the
vena cava and right atrium, pressure at end diastole
reflects back to the catheter.
CENTRAL VENOUS PRESSURE
When connected to a manometer, the catheter
measures central venous pressure (CVP), an
index of right ventricular function.
CVP monitoring helps to assess cardiac function,
to evaluate venous return to the heart, and to
indirectly gauge how well the heart is pumping.
Methods to measure CVP
1. Indirect assessment:
Inspection of jugular venous pulsations in
2. Direct assessment:
Fluid filled manometer connected to
central venous catheter.
Methods to measure CVP contd...
1. Inspection of jugular venous pulsations in
No valve between Right atrium & Internal
Degree of distention & venous wave form
reflects information about cardiac function.
The central venous (CV) line also provides access
to a large vessel for rapid, high-volume fluid
administration and allows frequent blood
withdrawal for laboratory samples.
CVP monitoring can be done intermittently or
The catheter is inserted percutaneously or using a
Typically, a single lumen CVP line is used for
intermittent pressure readings.
To measure the patient’s volume status, a
disposable plastic water manometer is attached
between the I.V. line and the central catheter
with a three or four-way stopcock.
CVP is recorded in centimeters of water (cm
H2O) or millimeters of mercury (mm Hg) read
from manometer markings.
Normal CVP ranges from 5 to 10 cm H2O or 2 to 6
Any condition that alters venous return,
circulating blood volume, or cardiac
performance may affect CVP.
If circulating volume increases (such as with
enhanced venous return to the heart), CVP rises.
If circulating volume decreases (such as with
reduced venous return), CVP drops.
Relationship between water
manometer and calibrated
In terms of pressure
1cm H2O = 0.73 mmHg.
1 mmHg = 1.36 cm H2O.
Methods to measure CVP contd...
2. Fluid filled manometer connected to central
venous catheter :
CVP is measured using a column of water in a
CVP is the height of the column in cms of H2O
when the column is at the level of right atrium.
Advantage: Simplicity to measure.
Disadvantage: 1) Inability to analyze the CVP
2) Relatively slow response of the water column
to changes in intrathoracic pressure.
Measurement of CVP cont…
3. Calibrated transducer
Automated, electronic pressure monitor.
Pressure wave form displayed on an
oscilloscope or paper.
Direct observation of waveform.
INDICATIONS FOR CENTRAL
1. Central venous pressure monitoring
2. Pulmonary artery catheterization &
3. Transvenous cardiac pacing
4. Temporary hemodialysis
5. Drug administartion
Concentrated Vasoactive drugs
Agents irritating to peripheral veins
Prolong antibiotic therapy
6. Rapid infusion of fluids
7. Aspiration of air emboli
8. Inadequate peripheral intravenous access
9. Sampling site for repeated blood testing
CVP measurement & intrathoracic
CVP measurement is influenced by changes in
It fluctuates with respiration.
Decreases in spontaneous inspiration.
Increases in positive pressure ventilation.
CVP should be taken at the end expiration.
PEEP applied to the airway at the end of
exhalation , may be partially transmitted to the
intrathoracic structures ► measured CVP will be
Techniques of central venous
1. Catheter over the needle
Longer version of a conventional intravenous
Catheter is larger than needle ► reduces
the leakage of blood from the insertion site.
Accidental arterial puncture can occur due to
Over insertion can damage the vein.
2. Catheter over guidewire ( Seldinger technique)
Preferred method of insertion.
18-20 G, small diameter needle is used.
A guide wire passed down the needle in to
the vein and needle removed.
Guidewire commonly has flexible J shaped tip
1. Reduces the risk of vessel perforation.
2. Helps negotiate valves in vein.
Once the wire is placed in the vein catheter is
passed over it.
3. Catheter through the needle or through
Catheter passed through a cannula or
needle placed in the vein.
Hole made in the vein by the needle larger
than the catheter ► some degree of
blood leakage around the site.
Withdrawal of catheter through needle risks
shearing off catheter
Routes of access of central vein
COMMONLY USED VEINS :
1. Subclavian vein
2. Internal jugular vein
3. Femoral vein
4. Basilic vein (Antecubital fossa )
ROUTES OF ACCESS CONTD…
LESS COMMONLY USED VEINS-
1. Axillary ( Anterior & lateral approach )
2. External jugular
3. Brachial ( Mid- upper arm approach )
4. Cephalic ( Ante- cubital fossa approach )
5. Brachio cephalic ( Supra – clavicular
ASSESSMENT of the patient
Regarding procedures, alternative
procedures, advantages & disadvantages,
risk involved, care of the device & removal of
2. Informed consent
4. Physical examination
General physique, height, weight, physical
features- bull neck, breasts, goitre, stoma,
5. Vascular assessment
Anatomy of peripheral & central veins & their
H/o previous CVP catheterisation.
Any evidence of venous thrombosis caused by
presence of Central Venous Access Device.
Thorax, abdomen, upper & lower limbs, neck
→ presence of dilated collaterals, swelling,
any sign of thrombosis or stenosis of veins.
6. Respiratory function assessment
Chest X- ray: To rule out emphysema/ COPD
CT chest: Large effusion/ collapse.
7. CVS assessment
Implanted pacemakers & defibrillators: Rule
out catheters interfering with the position of
leads of these devices & infection of such
8. Neurological assessment
Level of conciousness.
Effects of sedatives & analgesic drugs.
Paralysed limb- inc risk of unrecognised
extravasation of drugs.
9. Fractures & arthritis
Fracture clavicle- CVAD should be placed on
opp. side or jugular approach should be used.
Fracture of UL bones- C/I for PICC.
10. Laboratory assessment
Serum Electrolytes – within normal range.
↑ Serum K+ - Risk of arrhythmias.
APTT : 22 - 34 sec
PT : 10.5 - 13.5 sec
Platelet : 150 - 400 × 109 /L
Warfarin : Either stopped or converted to
heparin 3 days beforehand.
INR : 1.5 or below should be achieved
IV Unfractionated heparin : Stopped 3 hrs
before insertion & restarted when haemostasis
LMWH : 12-24 hrs.
Document all dressing, tubing, and solution
Document the patient’s tolerance of the
The date and time of catheter removal, and the
type of dressing applied.
Note the condition of the catheter insertion site
and whether a culture specimen was collected.
Note any complications and actions taken.