• “Repeated or continuous observations or measurements of the patient, his or her physiological function, and the function of life support equipment, for the purpose of guiding management decisions, including when to make therapeutic interventions, and assessment of those interventions” [Hudson, 1985, p. 630].

• A patient monitor may not only alert caregivers to potentially life-threatening events; many provide physiologic input data used to control directly connected life-support devices.

High performanceCPU

Outer O/P

Serial interface

Printer

Keyboard

Data storage

Rom

RRam

A/Dconverter

Analog mux

Measuringdevice

ProcessInterrupt

Videoprocessor

Display

• Care begins with collecting data and assessing the patient’s current status

• Through cognitive processes specific to the discipline: – diagnostic labels are applied, – therapeutic goals are identified with timelines for evaluation, and – therapeutic interventions are selected and implemented

• At specified intervals: – patient is reassessed, – effectiveness of care is evaluated, and – therapeutic goals and interventions are continued or adjusted as

needed

• If the reassessment shows that the patient no longer needs care, services are terminated

WORKING

• STANDARD I

– Qualified anesthesia personnel continuously present

• STANDARD II: Continually evaluate

– Oxygenation

• Inspired gas: O2 analyzer with low O2 alarm*

• Blood oxygenation: POx, color assessment*

– Ventilation

• Chest excursion, Reservoir breathing bag observation, auscultation

• Quantitative ETCO2

• Expired volume quantification*

• ETT/LMA position verified with clinical assessment + ETCO2

• Disconnect alarm when using PPV

ASA Standards for Basic Anesthesia Monitoring

Automated oscillometric

NIBP monitor

• Non-invasive, automated

• Air pump with deflation valve to control cuff pressure

• Transducer measures cuff pressure and pressure oscillations within the cuff

• Systolic and MAP correlate well with invasive BP measurements, but diastolic usually 10 mmHg higher with this method

ECG

• Continuous visual display

• Monitors cardiac electrical activities only, it does not

measure heart function

• Early detection of

– Dysrhythmias:

• Lead II

– Myocardial ischemia:

• Lead V5

– Electrolyte changes

• Allow calculation of HR

Pulse Oximetry

• Practical, non-invasive, reliable monitoring of SpO2 as a reflection of SaO2

• Early warning of arterial hypoxemia• the need for PaO2 determinations (ABGs)• LED measures absorption of specific wavelengths of light

during arterial pulsations• Computer calculates SpO2

• SpO2 > 90% correlates with PaO2 > 60 mmHg• Alarms for HR, SpO2 values• Acceptable in most cases: 92 <= SpO2 <= 100• O2 supplementation likely needed for SpO2 < 93

Capnography

• Continuous measurement of patient’s inhaled and exhaled [CO2]

• Waveform display more informative than the value

• Useful for evaluation of

– Esophageal intubation

– Disconnect in breathing circuit

– Rebreathing of CO2

– Cardiac arrest

– Malignant Hyperthermia / Thyroid storm

– Hypotension

– PE

• ETCO2 underestimates PaCO2 due to dead space ventilation