ASA Standards Revised for Ventiltion
Bhavani Shankar Kodali MD
American Society of Anesthesiologists (ASA) recently updated monitoring standards for ventilation that are defined below. Details of the ‘Standards’ can be found at the end of this document.
In October 2010, the ASA House of Delegates approved a change to the ASA “Standards for Basic Anesthetic Monitoring”. In order to give ASA members sufficient time to comply with this change, the House also approved that implementation be delayed until July 1, 2011. Specifically, Standard 3.2.4 under VENTILATION, METHODS was changed to read: “During regional anesthesia (with no sedation) or local anesthesia (with no sedation), the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs. During moderate or deep sedation the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs and monitoring for the presence of exhaled carbon dioxide unless precluded or invalidated by the nature of the patient, procedure, or equipment.” The intent is that during moderate or deep sedation (regardless of location), the adequacy of ventilation be evaluated by both continual observation of qualitative clinical signs and by monitoring for the presence of exhaled carbon dioxide. The House of Delegates recognized that there might be rare circumstances when it was not possible to accomplish this and added the following qualifier “unless precluded or invalidated by the nature of the patient, procedure, or equipment.”
Although this is the standard of care for all anesthesiologists, It is reasonable to believe that capnography should be used by all non anesthesiologists to monitor ventilation during sedation. This is because
- Hypoxia follows hypoventilation, or apnea and therefore capnography can recognize hypoventilation, airway obstruction, or apnea. This will facilitate corrective measures to be undertaken before the onset of hypoxia.
- Administration of oxygen maintains oxygenation for a longer interval after apnea and therefore might delay detection of apnea, or hypoventilation.
- Relying on pulse oximeter alone can decrease the margin of safety as corrective actions are taken only when pulse oximeter gives an alarm.
- Non anesthesiologists may not be as adept as anesthesiologists in assisting ventilation, or intubation, when required.
- Many sedation procedures are performed away from operating rooms and substantial time may be required before anesthesiologists arrives for help
STANDARDS FOR BASIC ANESTHETIC MONITORING
Committee of Origin: Standards and Practice Parameters
(Approved by the ASA House of Delegates on October 21, 1986, and last amended on
October 20, 2010 with an effective date of July 1, 2011)
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. These standards are not intended for application to the care of the obstetrical patient in labor or in the conduct of pain management.
1. STANDARD I
Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthetics, regional anesthetics and monitored anesthesia care.
1.1 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 which 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.
2. STANDARD II
During all anesthetics, the patient’s oxygenation, ventilation, circulation and temperature shall be continually evaluated.
2.1 Oxygenation –
2.1.1 Objective –
To ensure adequate oxygen concentration in the inspired gas and the blood during all anesthetics. STANDARDS FOR BASIC ANESTHETIC MONITORING
2.2 Methods –
2.2.1 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.*
2.2.2 Blood oxygenation: During all anesthetics, a quantitative method of assessing oxygenation such as pulse oximetry shall be employed.* When the pulse oximeter is utilized, the variable pitch pulse tone and the low threshold alarm shall be audible to the anesthesiologist or the anesthesia care team personnel.* Adequate illumination and exposure of the patient are necessary to assess color.*
3.1 Objective –
To ensure adequate ventilation of the patient during all anesthetics.
3.2 Methods –
3.2.1 Every patient receiving general anesthesia shall have the adequacy of ventilation continually evaluated. Qualitative clinical signs such as chest excursion, observation of the reservoir breathing bag and auscultation of breath sounds are useful. Continual monitoring for the presence of expired carbon dioxide shall be performed unless invalidated by the nature of the patient, procedure or equipment. Quantitative monitoring of the volume of expired gas is strongly encouraged.*
3.2.2 When an endotracheal tube or laryngeal mask is inserted, its correct positioning must be verified by clinical assessment and by identification of carbon dioxide in the expired gas. Continual end-tidal carbon dioxide analysis, in use from the time of endotracheal tube/laryngeal mask placement, until extubation/removal or initiating transfer to a postoperative care location, shall be performed using a quantitative method such as capnography, capnometry or mass spectroscopy.* When capnography or capnometry is utilized, the end tidal CO2 alarm shall be audible to the anesthesiologist or the anesthesia care team personnel.*
3.2.3 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.
3.2.4 During regional anesthesia (with no sedation) or local anesthesia (with no sedation), the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs. During moderate or deep sedation the adequacy of ventilation shall be evaluated by continual observation of qualitative clinical signs and monitoring for the presence of exhaled carbon dioxide unless precluded or invalidated by the nature of the patient, procedure, or equipment. STANDARDS FOR BASIC ANESTHETIC MONITORING
4.1 Objective –
To ensure the adequacy of the patient’s circulatory function during all anesthetics.
4.2 Methods –
4.2.1 Every patient receiving anesthesia shall have the electrocardiogram continuously displayed from the beginning of anesthesia until preparing to leave the anesthetizing location.*
4.2.2 Every patient receiving anesthesia shall have arterial blood pressure and heart rate determined and evaluated at least every five minutes.*
4.2.3 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, or pulse plethysmography or oximetry.
5. BODY TEMPERATURE
5.1 Objective –
To aid in the maintenance of appropriate body temperature during all anesthetics.
5.2 Methods –
Every patient receiving anesthesia shall have temperature monitored when clinically significant changes in body temperature are intended, anticipated or suspected.
† Note that “continual” is defined as “repeated regularly and frequently in steady rapid succession” whereas “continuous” means “prolonged without any interruption at any time.”
* Under extenuating circumstances, the responsible anesthesiologist may waive the requirements marked with an asterisk (*); 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.