Monitoring during anaesthesia

Monitoring during anaesthesia


Standards For Basic Intraoperative Monitoring

These standards apply to all anesthesia care although, in emergency circumstances, appropriate life support measures take precedence. These standards may be exceeded at any time based on the Judgment of the responsible anesthesiologist. They are intended to encourage quality patient care, but observing them cannot guarantee any specific patient outcome. They are subject to revision from time to time, as warranted by the evolution of technology and practice. They apply to all general anesthetics, regional anesthetics and monitored anesthesia care. This set of standards addresses only the issue of basic anesthetic monitoring, which is one component of anesthesia care. In certain rare or unusual circumstances, (1) some of these methods of monitoring may be clinically impractical, and (2) appropriate use of the described monitoring methods may fail to detect untoward clinical developments.  Brief interruptions of continual monitoring   may be unavoidable. It is recommended that when this is done, it should be so stated (including the reasons) in a note in the patient’s medical record. These standards are not intended for application to the care of the obstetric patient in labor or in the conduct of pain management.)


Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthetics, regional anesthetics, and monitored anesthesia care.

Objective: Because of the rapid changes in patient status during anesthesia, qualified anesthesia personnel shall be continuously present to monitor the patient and provide anesthesia care. In the event there is a direct known hazard, e.g. Radiation, to the anesthesia personnel that might require intermittent remote observation of the patient, some provision for monitoring the patient must be made. In the event that an emergency requires the temporary absence of the person primarily responsible for the anesthetic, the best judgment of the anesthesiologist will be exercised in comparing the emergency with the anesthetized patient’s condition and in the selection of the person left responsible for the anesthetic during the temporary absence.


During all anesthetics, the patient’s oxygenation, ventilation, circulation, and temperature shall be continually evaluated.


Objective: To ensure adequate oxygen concentration in the inspired gas and the blood during all anesthetics.

Methods. :

(1)        Inspired gas: During every administration of general anesthesia using an anesthesia machine, the concentration of oxygen in the patient breathing system shall be measured by an oxygen analyzer with a low-oxygen-concentration –limit alarm in use.

(2)        Blood oxygenation: During all anesthetics, a quantitative method of assessing oxygenation such as pulse oximetry shall be employed. Adequate illumination and exposure of the patient is necessary to assess color.


Objective: To ensure adequate ventilation of the patient during all anesthetics.


(1)        Every patient receiving general anesthesia shall have the adequacy of ventilation continually evaluated. While qualitative clinical signs such as chest excursion, observation of the reservoir breathing bag, and auscultation of breath sounds may be adequate, quantitative monitoring of the CO2 content and / or volume of expired gas is encouraged.

(2)        When an endotracheal tube is inserted, its correct positioning in the trachea must be verified by clinical assessment and by identification of carbon dioxide in the expired gas. End-tidal CO2 analysis, in use from the time of endotracheal tube placement, is strongly encouraged.

(3)        When ventilation is controlled by a mechanical ventilator, there shall be in continuous use a device that is capable of detecting disconnection of components of the breathing system. The device must give an audible signal when its alarm threshold is exceeded.

(4)        During regional anesthesia and monitored anesthesia care, the adequacy of ventilation shall be evaluated, at least, by continual observation of qualitative clinical signs.


Objective: To ensure the adequacy of the patient’s circulatory function during all anesthetics.

Methods. :

1.   Every patient receiving anesthesia shall have the electrocardiogram continuously displayed from the beginning of anesthesia until preparing to leave the anesthetizing location.

2.   Every patient receiving anesthesia shall have arterial blood pressure and heart rate determined and evaluated at least every five minutes.

3.   Every patient receiving general anesthesia shall have, in addition to the above, circulatory function continually evaluated by at least one of the following: palpation of a pulse, auscultation of heart sounds, monitoring of a tracing of intra-arterial pressure, ultrasound peripheral pulse monitoring, of pulse plethysmography or oximetry.


Objective: To aid in the maintenance of appropriate body temperature during all anesthetics.

Methods: There shall be temperature are intended, anticipated, or suspected, the temperature shall be measured.

All the monitoring devices must be attached before induction of anesthesia  and their use continued until the patient has recovered from the effects of anesthesia. All information  provided by monitoring devices should be recorded in the patient’s  notes. Trend display and printing devices are recommended, as  they allow the anesthetist to concentrate on managing the patient in emergency situations.

Use of a nerve stimulator whenever a muscle relaxant is used is an essential part of monitoring.

Additional (mainly invasive) monitoring devices may be required for some patients or for some types of operation, e.g. invasive monitoring of vascular or intracranial pressures, cardiac output, evoked potentials, electroencephalograph, jugular venous oximetry, bispectral index, urine output, arterial blood gas analysis, other biochemical variables (glucose) etc.

When handing over to recovery staff, anesthetists should issue clear instructions concerning monitoring during postoperative care. Monitoring of arterial oxygen saturation and non-invasive monitoring of blood pressure are essential. An electro cardiograph, nerve stimulator, capnograph and a means of measuring temperature must be immediately available.

Standards of care and monitoring during transfer of sedated, anesthetized or unconscious patients should be as high as during administration of anesthesia. Oxygen saturation, the electrocardiogram and arterial pressure should be monitored in all patients. Additional monitors may be required in some circumstances.  Airway pressure, tidal volume and expired carbon dioxide concentration should be monitored continuously if the lungs are ventilated artificially.

Some of the indications for using additional monitors are;

Operative duration > 3h

Blood loss > 10% blood volume

Operations on chest, CNS, CVS

Clinically significant co-existing disease.

Email : [email protected]