Transcript Document

Central Venous Pressure and
Central lines
Big Lines for Big Problems
Challenging Knowledge
Before starting this module; Answer the
following questions
(1) What sites are used to site a CVL?
(2) What is the normal CVP?
(3) What are the basic treatments for a CVP
of -1cm of H20
(4) What are the essential items required to
measure a CVP?
Learning Outcomes
By the end of this module you should
(1) Be aware of factors which affect the CVP
(2) Recognise normal and abnormal CVP values
(3) Be able to set up the manometer system to
measure a patient’s CVP
(4) Be able to measure a CVP and interpret the
value
(5) Be aware of the initial management for high and
low values
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.
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.
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
positioned
supine on
the bed
•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
Three way tap
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
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)
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
Low
( may be normal or
high due to
venoconstriction)
Tachycardia
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
Tachycardia
Urine output
‘falling’ below 30ml /hr
Poor capillary refill
Hypovolaemia
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
treat underlying cause
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
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?
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.
(1)What is the descriptive term given to this clinical state?
(2)List your further management?
Learning Outcomes
At the end of this module you should
(a) Be aware of the factors affecting the CVP.
(b) Be able to set up a CVP manometer
system.
(c) Be able to measure a CVP from a patient.
(d) Be able to interpret the result.
(e) Be able to institute initial management
based on the result.