CENTRAL VENOUS PRESSURe monitoring

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CENTRAL VENOUS PRESSURe monitoring

• Dr. NEHA KANOJIA

University College of Medical Sciences GTB
Hospital, Delhi
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CONTENTS

• METHODS
• TECHNIQUES
• COMPLICATIONS
• NORMAL WAVE FORMS
• ABNORMAL WAVE FORMS

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What is cvp ?

• CVP is the pressure measured at the junction of
  the superior venae cavae and the right atrium.
• It reflects the driving force for filling of the
  right atrium ventricle.
• It reflects the relationship of blood volume to
  the capacity of the venous system.

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• Normal CVP in an awake , spontaneously breathing
  patient - 1-7 mmHg or
• 5-10 cm H2O.
• Mechanical ventilation- 3-5 cm H2O higher.

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Historical background

1863 Chauveau Mary ( Paris ). Developed a special double lumen catheter. Systemic study, description interpretation of intracardiac pressure recordings in horse.
1876 Claude Bernard ( France ). First cardiac catheterisation. To determine the temp. of blood in rt. lt. ventricles.
1929 Forssman. Passed ureteric catheter(4 Fr) to his rt. atrium through rt. cubital fossa vein.
1949 Duffy. Introduced a catheter into the IVC through femoral vein.
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Historical background contd

1952 Aubaniac. Subclavian vein cannulation.
1953 Seldinger. CVP Catheter replacement method using guidewire.
1967 Spranklen et al. Axillary vein cannulation.
1969 English et al. IJV cannulation.
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Methods to measure cvp

• 1. Indirect assessment-
• Inspection of jugular venous pulsations in neck.
• 2. Direct assessment-
• Fluid filled manometer connected to central
  venous catheter.
• Caliberated transducer.

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Methods to measure cvp contd...

• Inspection of jugular venous pulsations in neck.
• No valves b/w rt. atrium IJV.
• Degree of distention venous wave form
  information about cardiac function.

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Fig. showing measurement of jvp
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• 2. Fluid filled manometer connected to central
  venous catheter- measured using a column of water
  in a marked manometer.
• 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- Inability to analyze the CVP
  waveform.
• -Relatively slow response of the water column
  to changes in intrathoracic pressure.

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measurement of CVP

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Measurement of cvp cont

• Caliberated transducer.
• Automated, electronic pressure monitor.
• Pressure wave form displayed on an oscilloscope
  or paper.
• Advantages-
• More accurate.
• Direct observation of waveform.

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Pressure transducer
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• Relationship between water manometer and
  caliberated transducer in terms of pressure
• 1cm H2O 0.73 mmHg.
• 1.36 cm H2O 1 mmHg.

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Cvp measurement intrathoracic pressure

• CVP measurement is influenced by changes in
  intrathoracic pressure.
• It fluctuates with respiration.
• Decreases -spontaneous inspiration.
• Increases -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 CVP measured will be
  higher.

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Techniques of central venous cannulation

• Catheter over the needle
• Longer version of a conventional intravenous
  cannula.
• Catheter is larger than needle reduces
  the leakage of blood from the insertion site.
• Accidental arterial puncture can occur d/t
  larger
• needle.
• Over insertion can damage the vein.

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TECHNIQUES CONTD

• 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.

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• Catheter through the needle or through cannula.
• 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
• Catheter embolisation

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INDICATIONS FOR CENTRAL VENOUS CANNULATION

• Central venous pressure monitoring
• Pulmonary artery catheterization monitoring
• Transvenous cardiac pacing
• Temporary hemodialysis
• Drug administartion
• Conc. Vasoactive drugs
• Hyperalimentation
• Chemotherapy
• Agents irritating to peripheral veins
• Prolong antibiotic therapy

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INDICATIONS CONTD

• 6.Rapid infusion of fluids
• Trauma
• Major surgery
• 7.Aspiration of air emboli
• 8.Inadequate peripheral intravenous access
• 9.Sampling site for repeated blood testing

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routes of access of central vein

• Commonly used veins
• Subclavian vein
• Internal jugular vein
• Femoral vein
• Basilic vein (antecubital fossa )

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ROUTES OF ACCESS CONTD

• LESS COMMONLY USED VEINS-
• Axillary ( anterior lateral approach )
• External jugular
• Brachial ( mid- upper arm approach )
• Cephalic ( ante- cubital fossa approach )
• Brachio cephalic ( supra clavicular approach )

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ROUTES OF ACCESS
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ASSESSMENT of patient

• Information-
• Regarding procedures, alternative procedures,
  adv. disadv., risk involved, care of the
  device removal of device.
• Informed consent.
• Allergies
• Physical examination -
• General physique, height, weight, physical
  features- bull neck, breasts, goitre, stoma, open
  wounds.
• Vascular assessment
• Anatomy of peripheral central veins their
  variants.

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• H/o previous CVP catheterisation.
• Any evidence of venous thrombosis caused by
  presence of CVAD.
• Thorax, abdomen, upper lower limbs, neck ?
  presence of dilated collaterals, swelling
  s/o thrombosis or stenosis of veins.
• 6. Respiratory function assessment
• Chest X- ray. To r/o emphysema/ COPD
  
  
• CT chest. Large effusion/ collapse.
• 7. CVS assessment
• Implanted pacemakers defibrillators r/o
  catheters interfering with the position of leads
  of these devices infection of such devices.

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• 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
• S.E. with in normal range.
• ? S. K - Risk of arrhythmias.

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• 11.Coagulation assessment
• APTT- 22-34 sec
• PT 10.5- 13.5 sec
• Platelets 150-400 109 /l
• Warfarin therapy- either stopped or converted to
  heparin 3 days beforehand.
• INR- 1.5 or below should be achieved
• I/V unfractionated heparin- stopped 3 hrs before
  insertion restarted when haemostatis is
  achieved.
• LMWH- 12-24 hrs.