invasive monitoring

• Invasive monitoring


  Falls into two main sub-categories: Arterial monitoring and Venous monitoring
• Arterial Lines


  To monitor haemodynamic status in more detail, monitor real-time response to vasoactive drugs, arterial blood sampling, potentially assist in the determination of cardiac output
• Blood pressure equation


  BP = Blood pressure, CO = Cardiac output, SVR = Systemic vascular resistance, HR = Heart rate, SV = Stroke volume, CO = CO x SVR, HR x SV
• Arterial Lines


  Specifically designed cannulas that are inserted into an artery to give beat-by-beat readings of a patients blood pressure, most common site is the radial artery, but femoral, brachial, axillary arteries are also used
• Arterial Monitoring - what kit do you need?


  • Arterial cannula
  • 2ml or 5ml syringe or ultrasound
  • Transducer set - run through with 0.9% normal saline
  • Cannula dressings
  • Arterial line label
  • Transducer cable
  • Transducer block
• Insertion Techniques


  • Seldinger Technique -over a guidewire
  • Cannula-over-needle Technique
  • Single wall puncture
  • Transfixing
• Transducer set


  Vented caps, Zeroing - You must zero your invasive monitoring line prior to using, by zeroing the A-line you ensure that only the actual pressure from the patient will be measured by the transducer, the transducer must be positioned at an anatomically consistent site (this is known as phlebostatic axis)
• Arterial Lines - potential complications


  • Haemorrhage
  • Infection
  • Blockage
  • Clotting
  • Air Emboli
  • Interruption to peripheral circulation
• NEVER ADMINISTER IV DRUGS OR FLUIDS THROUGH AN ARTERIAL LINE!!
• Central Venous Access


  A central venous catheter is a catheter with a tip that lies within the proximal 1/3 of the superior vena cava, they can either be inserted via a peripheral vein (PICC line) or via a central vein (internal jugular and subclavian are the most common sites)
• Why might we insert a central line?


  Administer certain drug therapies that might injury peripheral vessels, Give an indication of IV fluid therapy effectiveness, Measure venous return to the heart
• Types of central venous catheter


  • Non-tunnelled
  • Peripherally inserted
  • Tunnelled
  • Totally implantable
• Central Venous Pressure (CVP)


  A "normal" CVP reading is between 5-10 cm H2O
• Central Venous Access - complications


  • Pneumothorax
  • Haemothorax
  • Cardiac dysrhythmia
  • Accidential arterial puncture
  • Nerve damage
  • Air Emboli
  • Pulmonary Emboli
  • Infection
• Prior to use, a chest x-ray should be taken to confirm the location of the line placement. It is critically important that when you remove the line the patient is supine/head down.
• Pulmonary Artery Catheters (PAC)


  PACs are balloon tipped thermodilution catheters around 110 cm long, they are inserted into a large vein and then floated into the pulmonary artery, its function along with other clinical observations is to determine the efficacy of the heart
• Why insert PACs?


  They assess: Shock states, Cardiovascular function, Pulmonary function, Haemodynamic function - peri and post cardiac surgery, Fluid requirements and effectiveness of fluid therapy, Multi-organ failure
• PAC - complications


  • All of the complications we listed for CV access
  • Ventricular arrhythmia
  • Thromboembolic events
  • Air embolism from ruptured balloon
  • Pulmonary infarction
  • RBBB
  • Pulmonary Artery rupture
  • Damage to the valves
• The development of non-invasive monitoring to give us the same information has been improved!
• Transoesophageal Echocardiography (T.O.E.)


  T.O.E. is a ultrasound probe that is inserted into the oesophagus and gives clinical information pertaining to the functionality of the heart, it is a standard piece of monitoring used in cardiac surgery, it gives you high-quality 'real-time' images of anatomy and function of the heart, Doppler techniques allow recognition of the direction and velocity of blood flow
• Lithium Dilution Cardiac Output (LiDCO)


  LiDCO is a minimally/non-invasive technique of continuous cardiac output monitoring, the latest LiDCO monitors can derive the Stoke volume and heart rate from the blood pressure waveform
• Ways to measure Intra-cranial pressure (ICP)


  • Intraventricular catheter
  • Subdural screw
  • Epidural sensor
• Bispectral Index (BIS) monitor


  Allows anaesthetists to assess the depth of anaesthesia by measuring the cerebral electric activity via an electroencephalogram (EEG)