Monitoring in Anaesthesia and ICU

• The presence of an appropriately trained and experienced anaesthetist is the main determinant of patient safety during anaesthesia
• Many studies have shown that adverse incidents and accidents are frequently attributable, at least in part, to error by anaesthetists
• Monitoring will not prevent all adverse incidents or accidents in the peri-operative period
• There is substantial evidence that monitoring reduces the risks of incidents and accidents
• Monitoring does this both by detecting the consequences of errors, and by giving early warning that the condition of a patient is deteriorating
• Monitor


  To check systematically, or to keep watch over
• In the context of anaesthesiology, monitoring means using both our senses and electronic devices to continually or continuously measure important variables in an anaesthetised patient
• Harvey Cushing first started our recording of vital signs and patient data a century ago
• Recording vital signs and patient data can serve as evidence of intraoperative management in case of medicolegal summons and can also serve as reference for future anaesthetic exposures
• Presence of anaesthetist


  • An anaesthetist of appropriate experience, or fully trained Physician Assistant (Anaesthesia) PA (A) under the supervision of a consultant anaesthetist, must be present throughout general anaesthesia, including any period of cardiopulmonary bypass
  • Using both clinical skills and monitoring equipment, the anaesthetist must care for the patient continuously
• Standards of monitoring


  • The same standards must apply when an anaesthetist is responsible for a local/regional anaesthetic or sedative technique or even monitored anaesthetics care for an operative procedure
  • When there is a known potential hazard to the anaesthetist, for example during x-ray imaging, facilities for remotely observing and monitoring the patient must be available
  • Accurate records of the values determined by monitors must be kept
• Minimum monitoring data


  • Heart rate
  • ECG
  • Temperature
  • Blood pressure
  • Peripheral oxygen saturation
  • End-tidal carbon dioxide
  • Anaesthetic vapour concentration, if volatile anaesthetic agents or nitrous oxide are used
• Work station / Equipment check

  • It is the responsibility of the anaesthetist to check all equipment before use
  • Ensure that they are familiar with all the equipment they intend to use and that they have followed any specific checking procedures recommended by individual manufacturers
• Oxygen delivery


  • The use of an oxygen analyser with an audible alarm is essential during anaesthesia
  • The anaesthetist should check and set appropriate oxygen concentration alarm limits
  • Most modern anaesthetic machines have built-in oxygen analysers that monitor both inspired and expired oxygen concentrations
• Breathing systems /circuits


  • During spontaneous ventilation, observation of the reservoir bag may reveal a leak, disconnection, high pressure or abnormalities of ventilation, thereby serving as a good monitor for respiratory system during spontaneous ventilation/breathing
• Vapour analyser


  • The use of a vapour analyser is essential during anaesthesia whenever a volatile anaesthetic agent or nitrous oxide is in use
  • The end-tidal concentration should be documented on the anaesthetic record
• Devices


  • Many devices used in anaesthetic practice need their own checks and monitoring
  • This includes monitoring the cuff pressure of tracheal tubes and cuffed supra-glottic airway devices
  • Cuff pressure manometers should be used to avoid exceeding manufacturers' recommended intracuff pressures which can be associated with increased patient morbidity
• Monitoring the patient


  • During anaesthesia, the patient's physiological state and adequacy of anaesthesia need continual / continuous assessment
  • Monitoring devices supplement clinical observation in order to achieve this
  • Appropriate clinical observations may include mucosal colour, pupil size, response to surgical stimuli and movements of the chest wall and/or the reservoir bag
  • The anaesthetist may undertake palpation of the pulse, auscultation of breath sounds and, where appropriate, measurement of urine output and blood loss
  • A stethoscope must always be available
  • Monitoring must continue until the patient has recovered from anaesthesia
• Minimum monitoring devices


  • Pulse oximeter
  • Non invasive blood pressure
  • Electrocardiogram
  • Temperature for any procedure > 30 min duration
  • Capnography – end tidal ETCO2
  • Monitoring of inspired and expired oxygen, nitrous oxide and volatile anaesthetic agent if used
• Additional monitoring devices


  • Airway pressure
  • Peripheral nerve stimulator if neuromuscular blocking drugs used
• Additional monitoring


  • Some patients will require additional monitoring, for example intravascular pressures, cardiac output or biochemical or haematological variables depending on patient and surgical factors
  • The use of additional monitoring is at the discretion of the anaesthetist
• Use of depth of anaesthesia monitors


  • Recommended when patients are anaesthetised with total intravenous techniques and neuromuscular blocking drugs, to reduce the risk of accidental awareness during general anaesthesia
• Cardiac monitors


  • NIBP
  • ECG
  • Invasive arterial blood pressure
  • Central venous catheterization/pressure
  • Pulmonary artery catheterization/pressure
• Non-invasive Arterial BP monitoring techniques

  • Palpation
  • Doppler probe
  • Auscultation
  • Oscillometry
  • Arterial Tonometry
• Invasive blood pressure monitoring

  • Indications: Hypotension, Anticipation of wide blood pressure swings, End-organ disease necessitating precise beat-to-beat BP regulation, Need for multiple arterial blood gas analyses
  • Contraindications: If possible, catheterization should be avoided in arteries without documented collateral blood flow or in extremities where there is suspicion of preexisting vascular insufficiency (e.g., Raynaud's phenomenon)
  • Techniques: The Radial artery is commonly cannulated because of its superficial location and collateral flow. Others are: Ulnar, brachial, femoral, dorsalis pedis and posterior tibial arteries and axillary artery
  • Complications: Haematoma, Bleeding, Vasospasm, Arterial thrombosis, Embolisation of air bubbles or thrombi, Necrosis of skin overlying the catheter, Nerve damage, infection, loss of digits, Unintentional intraarterial drug injection
• Central venous catheterization


  • Indications: For monitoring central venous pressure (CVP), For administration of fluid to treat hypovolaemia and shock, For administration of caustic drugs and total parenteral nutrition, For aspiration of air emboli, For insertion of transcutaneous pacing leads, For gaining venous access in patients with poor peripheral veins
  • Contraindications: Renal cell tumour extension into the right atrium or fungating tricuspid valve vegitations. Other contraindications relate to cannulation site.
  • Techniques: Central venous cannulation involves introducing a catheter into a vein so that the catheter's tip lies just above or at the junction of the superior vena cava and the right atrium. Measurement is made with a water column (cm H2o) or, preferably, an electronic transducer (mm Hg).
  • Veins: Basilic, External Jugular, Internal Jugular, Subclavian, Femoral
• Pulmonary Artery Catheterization


  • Indications: Monitoring pulmonary artery pressure and cardiac output in critically ill patients. Should be considered whenever cardiac index, preload, volume status, or the degree of mixed venous blood oxygenation need to be known. Patients at high risk for hemodynamic instability (e.g., recent myocardial infarction) or During procedures associated with high incidence of hemodynamic complications (e.g., thoracic aortic aneurysm repair)
  • Relative Contraindications: Complete left bundle branch block, Wolff-Parkinson-White syndrome, Ebstein's malformation
• Pulmonary monitors


  • Precordial & Esophageal stethoscopes
  • Pulse oximetry
  • Capnography
  • Anaesthetic gas analysis
• Neurologic system monitors


  • Electroencephalography
  • BIS (bispectral index scale)
  • Evoked potentials (somatosensory-evoked potentials, SEPs; auditory-evoked potentials, AEPs; motor-evoked potentials, MEPs)
• Miscellaneous Monitors


  • Urinary output
  • Peripheral nerve stimulation