ASA recommended monitoring

1. DR TR SHRESTHA, KMCTH

2. Monitoring in the past
▪ Visual monitoring of
respiration and clinical
appearance
▪ Finger on pulse
▪ Blood pressure
(sometimes)
The first operation under ether, 1846,
Boston Medical Library

3. 1970
▪ Most anesthesia mishaps due to human error
▪ Equipment contributed little to the problem
▪ Better designed equipment detect errors
▪ Vigilance aids can improve outcome by detecting
problems before causing harm
Cooper JB. Preventable Anesthesia Mishaps: A study of Human Factors.
Anesthesiology 1978;49:309-406

4. The greatest danger was circuit disconnection.
Which could easily be missed with the technology then

6. In early 1980s
▪ “The Deep Sleep, 6000 Will Die or Suffer Brain Damage”
▪ “If you are going to go into anesthesia, you are going on a
long trip and you should not do it in any way.”
▪ There are dangers from human error, carelessness and
a critical shortage of anesthesiologists.
▪ 1,000 times more dangerous than in an airplane 30,000
feet in the air.
(ABC Television 20/20 Report, April 22, 1982)
Pierce EC, Jr. The 34th Rovenstine Lecture: 40 years behind the mask: safety revisited.
Anesthesiology 1996;84:965-75

7. “no patient shall be harmed by anesthesia”
▪ Father of the modern anesthesia-safety
movement
▪ Anesthesia Patient Safety Foundation,
1985
▪ Electronic monitors to detect presence
of CO2 and O2 level
▪ Standards could improve outcome
Ellison C. Pierce (1928-2011)

8. The Monitoring Standards
▪ 1985 Harvard Anesthesia Monitoring Standard
▪ 1986 ASA Monitoring Standard
▪ Approved by ASA House of Delegates, October 21, 1986
▪ Extended the Harvard Monitoring Standard
▪ Encouraged the use of Pulse Oximetry, Capnography,
Airway gas flow
▪ Last amended on October 20, 2010
▪ Last affirmed on October 28, 2015

9. ▪ Apply to all general anesthetics, regional anesthetics and
monitored anesthesia care
▪ May be exceeded at any time based on the judgment of
anesthesiologist
▪ Intended to encourage quality patient care, but cannot
guarantee any specific patient outcome
▪ Subject to revision from time to time, as per the evolution
of technology and practice

10. STANDARD I
▪ Qualified anesthesia personnel shall be present in the room
throughout the conduct of all general anesthetics, regional
anesthetics and monitored anesthesia care.
▪ This precedes reliance on any instrumentation (as implied
in Standard II)
▪ Clearly indicates that the anesthesia provider brings
essential expertise and interpretation to monitoring
beyond information provided by equipment

11. STANDARD II
▪ During all anesthetics, the patient’s oxygenation,
ventilation, circulation and temperature shall be
continually evaluated.
▪ Minimal requirements for general anesthesia include
▪ Oxygen analyzer
▪ Pulse oximetry
▪ Capnography
▪ Electrocardiogram
▪ Blood pressure measurement
▪ Ability to assess temperature

12. Oxygenation
Objective
▪ To ensure adequate oxygen concentration in the inspired
gas and the blood during all anesthetics
Methods
▪ Inspired gas: Measurement of concentration of oxygen in
the patient breathing system by an oxygen analyzer with a
low oxygen concentration limit alarm
▪ Blood oxygenation: Use of pulse oximetry, qualitative
assessment of skin color, arterial blood gas sampling

13. Pulse oximetry
▪ Based on Beer-Lambert law & spectrophotometric analysis
▪ May be applied to fingers, toes, earlobes
▪ LEDs on one side send out two wavelengths of light
▪ Red (600 to 750 nm wavelength)
▪ Infrared (850 to 1000 nm wavelength)
▪ Pass through the vascular bed to other side of the sensor
▪ Reduced hemoglobin absorbs much more of the red light (660 nm)
▪ Oxyhemoglobin absorbs more infrared light (940 nm).
▪ Photodetector measures the amount light received

14. ▪ Performs plethysmographic analysis
▪ Differentiate pulsatile “arterial” signal from nonpulsatile signal from
“venous” absorption and other tissues: skin, muscle, and bone

15. ▪ Normal range in a healthy adult is 96% to 99%.
▪ Values above 88% may be acceptable in patients with lung
disease
▪ High pulse oximeter reading (SpO2) generally indicates
that oxygen is available in the lungs, taken up in the blood,
and delivered to distal tissues.
▪ A low SpO2 may be due to a problem along the above
pathway or due to an error in monitoring.

16. Limitations
▪ May be a late reporter of inadequate gas exchange
▪ Carboxyhemoglobin absorbs light similarly to oxygenated Hb at 660
nm ⇨ falsely elevated readings
▪ Methemoglobin absorbs light at both 660 and 940 nm, resulting in a
saturation of 85%, which does not correlate with the true saturation.
▪ Methylene blue, indocyanine green, indigo carmine, and isosulfan blue
injections ⇨ falsely low saturation readings
▪ Low saturations (below 80%) ⇨ falsely overestimated
▪ Low perfusion, motion, and nail polish (especially blue) may cause
Spo2 measurements to be uninterpretable or unreliable.

17. Ventilation
Objective
▪ To ensure adequate ventilation of the patient during all
anesthetics
Methods
▪ Evaluation clinically: chest excursion, observation of reservoir
breathing bag and auscultation of breath sounds
▪ Continual monitoring for the presence of expired CO2
▪ Continual ETCO2 analysis, by quantitative method- capnography,
capnometry or mass spectroscopy
▪ ETCO2 alarm should be audible

18. Capnography
▪ Capnography not only evaluates respiration but also
confirms of ET intubation and is diagnostic of various
pathologic conditions
▪ Capnometry⇨numeric measurement & display of CO2 level
▪ Capnography ⇨ expired CO2 level is graphically displayed
as a function of time and concentration
▪ The measurement of CO2 is based on infrared light
absorption to determine concentration.
▪ Normal PetCO2 is 2 to 5 mm Hg < arterial CO2 pressure

19. Capnogram
A B
C
D
E

20. Kodali BS.Capnography Outside the Operating Rooms. Anesthesiology.2013;118:192-201

21. Alteration in ETCO2
Increases in ETO2 Decreases in ETCO2
Change in CO2 Production
Increase in metabolic rate Decrease in metabolic rate
Hyperthermia Hypothermia
Sepsis Hypothyroidism
Malignant hyperthermia
Shivering
Hyperthyroidism
Change in CO2 Elimination
Hypoventilation Hyperventilation
Rebreathing Hypoperfusion
Pulmonary embolism

22. Circulation
Objective
▪ To ensure the adequacy of the patient’s circulatory function during all
anesthetics
Methods
▪ Display of continuous ECG from the start until preparing to leave OR
▪ Evaluation of arterial BP and heart rate at least every five minutes
▪ Evaluation of circulatory function continually by at least one of the
following
• Palpation of a pulse
• Monitoring of a tracing of intra-
arterial pressure
• Auscultation of heart sounds
• USG peripheral pulse monitoring
• Pulse oximetry

23. ECG
▪ A 3 or 5 lead electrode system is used for ECG monitoring in the
operating room.
▪ 3 lead system ⇨ electrodes on right arm, left arm & chest position
▪ Lead II usually monitored with a 3 lead system, as the axis of this
vector is similar to the P-wave axis
▪ P waves in lead II associated with QRS complex, sinus rhythm
▪ The chest electrode is usually placed in the left anterior axillary line at
the 5th interspace; referred to as the V5 precordial lead.
▪ A 5 lead electrode system adds a right leg and left leg electrode and
allows monitoring of vectors I, II, III, AVR, AVL, AVF and V5 .

24. ▪ Anaesthesia monitors are capable of analysis of the ST
segment as an indicator of myocardial ischemia.
▪ Depression or elevation of the ST segment may be
indicative of myocardial ischemia or infarction respectively.
▪ Monitoring leads II and V5 allows for detection of ischemia
in 95% of patients since it monitors a large area of the
myocardium.

25. Arterial Blood Pressure
▪ Estimation of the systolic BP by palpating the return of the
arterial pulse as an occluding BP cuff is deflated.
▪ Measurement of SBP and DBP by auscultation of Korotkoff
sounds.
▪ Mean arterial pressure= DBP + 1/3 (SBP – DBP)

26. ▪ Automated noninvasive BP: employ the oscillometric method to
estimate the arterial blood pressure
▪ Automatically inflate the BP cuff to occlude the arterial pulse at preset
time intervals.
▪ The cuff pressure is sensed by a pressure transducer.
▪ SP ⇨ maximum cuff pressure at which pressure oscillations can be
perceived
▪ MAP ⇨cuff pressure at which the amplitude of the oscillations is
greatest
▪ DP ⇨minimum cuff pressure at which pressure fluctuations can be
perceived

27. ▪ Invasive blood pressure monitoring uses an indwelling
arterial catheter coupled through fluid-filled tubing to a
pressure transducer.
▪ Arterial line established with a small (20 - 22 G) catheter in
a peripheral artery
▪ Radial artery: the most common site
▪ Transducer converts pressure into an electrical signal to be
displayed

28. ▪ Hemodynamically unstable patient
▪ Rapid changes in blood pressure or extremes of blood
pressure are anticipated
▪ Compromise of the patient’s respiratory function,
oxygenation, or ventilation is anticipated
▪ Metabolic derangements are anticipated
▪ Frequent arterial blood sampling
▪ Inability to utilize noninvasive BP measurements

29. Body temperature
Objective
▪ To aid in the maintenance of appropriate body temperature during all
anesthetics.
Methods
▪ Monitoring of temperature when clinically significant changes in body
temperature are intended, anticipated or suspected

30. ▪ Control temperature during induced hypothermia and rewarming
▪ Infants and small children prone to thermal lability due to high surface
area-to-volume ratio
▪ Adults subjected to large evaporative losses or low ambient
temperatures (with exposed body cavity, large volume transfusion of
unwarmed fluids, or burns) prone to hypothermia
▪ Febrile patients : risk of hyper- or hypothermia
▪ Patients with autonomic dysfunction unable to autoregulate body
temperature.
▪ Malignant hyperthermia is always a possible complication, and
temperature monitoring should always be available.

31. Monitoring Sites
▪ Axilla: Common site for noninvasive temperature determination and is
usually 1°F below body temperature.
▪ Nasopharyngeal temperature: measured at the posterior
nasopharynx, reflects the brain temperature. Performed by measuring
the distance from the external meatus of the ear to the external naris
and inserting the temperature probe to that distance.
▪ Tympanic membrane temperature
▪ Rectal temperature
▪ Esophageal temperature

32. References
▪ American Society of Anesthesiologists: Standards for basic
anesthetic monitoring, 2011
▪ Pino RM. Handbook of Clinical Anesthesia Procedures of
the Massachusetts General Hospital.9th ed.Boston:Wolters
Kluwer.2016
▪ Barash PG. Clinical Anesthesia.8th ed.Boston:Wolters
Kluwer.2017
▪ Sullivan P.Anaesthesiology for Medical Students.1st ed.
Canada:Department of Anaesthesia, Ottawa Civic
Hospital.1991
▪ Duke JC.Anesthesia Secrets. 5th ed. USA: Elsevier.2016
▪ Cooper JB. Preventable Anesthesia Mishaps: A study of
Human Factors. Anesthesiology.1978;49:309-406
▪ Pierce EC, Jr. The 34th Rovenstine Lecture: 40 years behind
the mask: safety revisited.Anesthesiology.1996;84:965-75
▪ Kodali BS.Capnography Outside the Operating Rooms.
Anesthesiology.2013;118:192-201