Monitoring in Anesthesia

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ContentsIntroduction

What is monitoring?Which, Why and How to monitor?

Level of monitoringStandards for basic intraoperative

monitoring ( ASA)Systematic monitoringConclusion

Monitoring: A Definition ... interpret available clinical data to help

recognize present or future mishaps or unfavorable system conditions

... not restricted to anesthesia (change “clinical data” above to “system data” to apply to aircraft and nuclear power plants)

What is monitoring?

to monere (การู้เฝ้�ารู้ะวั�ง, การู้เต$อนภั�ย) Physiologic parameter & Patient safety parameter Clinical skills & Monitoring equipment Data collection, interpretation, evaluation, decision Problem seeking, Severity assessment, Therapeutic

assessment, Evaluation of Anesthetic interventions

Patient Monitoring and Management

Involves …Things you measure (physiological measurement, such as BP or HR)

Things you observe (e.g. observation of pupils)

Planning to avoid trouble (e.g. planning induction of anesthesia or planning

extubation)

Inferring diagnoses (e.g. unilateral air entry may mean endobronchial

intubation)

Planning to get out of trouble (e.g. differential diagnosis and response

algorithm formulation)

Level of monitoring Routine / Specialize / Extensive Non-equipment / Non-invasive / Minimally invasive

/ Penetrating / Invasive / Highly invasive Systematic

Respiratory / Cardiovascular / Temperature/Fetal Neurological / Neuro-muscular / Volume status & Renal

Standards for basic intraoperative monitoring

( ASA)

Standards for basic intraoperative monitoring

( ASA : American Society of Anesthesiologists)

Standard I Qualified anesthesia personnel shall be present in the

room throughout the conduct of all GA, RA, MAC

Standard II During all anesthetics, the patient’s respiratory

(ventilation, oxygenation), circulation and temperature shall be continually evaluated

Monitoring in the Past Visual monitoring of

respiration and overall clinical appearance

Finger on pulse Blood pressure

(sometimes)

Monitoring in the Past

Finger on the pulse

Harvey Cushing Not just a famous neurosurgeon …

but the father of anesthesia monitoring Invented and popularized the

anesthetic chart Recorded both BP and HR Emphasized the relationship

between vital signs and neurosurgical events ( increased intracranial pressure leads to hypertension and bradycardia )

Examples of Multiparameter Patient MonitorsExamples of Multiparameter Patient Monitors

Some Specialized Patient MonitorsSome Specialized Patient Monitors

Depth of Anesthesia Monitor

Evoked Potential Monitor

Transesophageal Echocardiography

Cardiovascular monitoring Routine monitoring

Cardiac activity Non-invasive blood pressure ( NIBP )Non-invasive blood pressure ( NIBP ) Electrocardiography ( ECG )Electrocardiography ( ECG )

Advanced monitoringDirect arterial blood pressureCardiac filling pressure monitor

Central venous pressurePulmonary capillary wedge pressure

Cardiovascular monitoring

ElectrocardiographyCardiac activityArrhythmia: Lead IIMyocardial ischemia: ECG criteriaElectrolyte imbalancePacemaker function

Cardiovascular monitoring การู้บ่�าน การู้บ่�าน ECGECG 1. การู้ต-ด้ lead II, modified V5 2. การู้แปรู้ผล สาเห้ต� การู้รู้�กษา-arrhythmia : bradycardia, tachycardia, AF,

PVC, VT, VF-Myocardial ischemia-electrolyte imbalance

Cardiovascular monitoring

Non-invasive blood pressure (NIBP) Cuff: width 120-150 % limb diameter, air bladder includes

more than halfway around limb Manometer: aneroid, mercury Detector: manual, automated

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Cardiovascular monitoring Non-invasive blood pressure

Inaccurate: cuff size, inflated pressure, shivering, cardiac arrhythmia, severe vasoconstriction

Proper application Narrow cuff Loose cuff

Cardiovascular monitoring Direct arterial pressure monitor

Indications Continuous blood pressure monitor:

anticipated cardiovascular instability, direct manipulation of cardiovascular system, inability to accurate measurement directly

Frequent arterial blood sampling: ABG, Acid-base / electrolyte / glucose disturbance, Coagulopathies

Cardiovascular monitoring Direct arterial pressure monitor

ContraindicationsLocal infectionImpaired blood circulation: Raynaud’s

phenomenon, DMRisks of thrombosis: hyperlipidemia, previous

brachial artery cannulation Modified Allen’s test ??? ( การู้บ่�านข้�อที่!%เที่�าไรู้

แล�วัค์ะ)

Cardiovascular monitoring Direct arterial pressure monitor

Complications Direct trauma: AV-fistula, Aneurysm Hematoma Infections Thrombosis Embolization Massive blood loss

Cardiovascular monitoring Cardiac filling pressure monitor

Frank-Starling curve: optimum Preload maximize ventricular performance (Stroke volume, CO.)

Preload = Myocardial fiber length (2.2 micron)LV Preload LVEDV LVEDP LAP PCWP

PAP RVP RAP CVP Myocardium function, LV compliance, Mitral valve, Airway

pressure, Pulmonary vascular resistance, Pulmonic valve, Tricuspid valve

Cardiovascular monitoring Cardiac filling pressure monitor

LV Preload LVEDV LVEDP LAP PCWP PAP LVEDP RVEDP RAP CVP

Cardiovascular monitoring Cardiac filling pressure monitor

PCWP: Pulmonary capillary wedge pressure CVP: Central venous pressure

Cardiovascular monitoring PCWP: Pulmonary capillary wedge pressure CVP: Central venous pressure

Fluid Challenge testFluid Challenge test to optimize preload and maximize Cardiac performance

Respiratory monitoring Ventilatory monitoring Oxygenation monitoring Machine and Circuit monitoring

Clinical skillsMonitoring devices

Ventilatory monitoring Clinical skills

Direct observation: rate, rhythm, volume of respirationAuscultation: precordial, esophageal stethoscopePalpation: reservoir bag movement

Monitoring devicesSpirometerAirway pressure manometerCircuit disconnection alarm

Ventilatory monitoring Capnometer (End-tidal CO(End-tidal CO22 analysis analysis)

relationship with PaCO2 : ETCO2 < PaCO2 ~ 3-6 mmHgmainly depends on dead space ventilationnormal value 30 – 35 mmHg Infrared absorption spectrographyMain-stream VS. Side-stream

Ventilatory monitoring Capnogram : normal curve

1. Dead space air (no CO2)

2. Mixed bronchus & alveolus air (CO2 upstroke)

3. Alveolus air (CO2 plateau)Inspiration ETCO2

12

3

Ventilatory monitoring Capnometer (End-tidal CO2 analysis)

Most useful in detection of Esophageal intubation, airway or circuit disconnection

Useful in CO2 rebreathing, partial recovery of neuro-muscular blockade, good predictor of successful CPR

การู้บ่�าน (เข้!ยน waveform of ET-CO2 และสาเห้ต�) Capnograph-esophageal intubation-bronchial intubation-airway obstruction-circuit disconnect-circuit leakage-partial rebreathing-spontaneous breathing (recovary of neuromuscular blockade)-hypoventilation

Oxygenation monitoring Clinical skills

Direct observation: impaired mental function, sympathetic overactivities, appearance(+ cyanosis)

Auscultation: wheezing, crepitation Monitoring devices

Arterial blood gas analysisPercutaneous O2 measurementPulse oximeter

Oxygenation monitoring

Pulse oximeterPercent of oxyhemoglobin

/ total hemoglobinOxyhemoglobin absorp

940 nm.Deoxyhemoglobin absorp

660 nm.Caution: SpO2 PaO2

Oxygenation monitoring Pulse oximeterPulse oximeter

SpO2 correlates with PaO2 as in Oxygen-hemoglobin dissociation curve

SpO2 90 PaO2 60 mmHg

(moderate hypoxemia)

75 40 mmHg

(mixed venous oxygen sat.)

50 27 mmHg

(P50)

Oxygenation monitoring Pulse oximeter artifacts

Abnormal hemoglobin: COHb, MetHb, HbFDye: Methylene blueAnemiaAmbient lightArterial saturationBlood flowMotionNail polishElectro-cautery

การู้บ่�าน Wave form Pulse oximeter Pulse oximeter artifacts กรู้ะที่บ่ต�อการู้

แปรู้ผลอย�างไรู้ Cause of Rt-Lt shift of oxygen-

hemoglobin dissociation curve

Machine & circuit monitoring Safety system

DISS, PISS, Quick disconnection adaptorOxygen fail-safe valve, Oxygen supply failure alarm

Oxygen analyzer Airway gas composition

Clinical skills: flowmeters, vaporizersMonitoring devices: Infrared spectrometer

Depth of Anesthesia Clinical Signs

eye signs

respiratory signs

cardiovascular signs

CNS signs

EEG monitoring

Facial EMG monitoring (experimental)

Esophageal contractility (obsolete)

Neurologic monitoringDepth of anesthesia ( BIS )EEGEvoked potentialsCerebral blood flow Intracranial pressure

Neuromuscular monitoringClinical skillsMonitoring device :

PERIPHERAL NERVE STIMULATOR

Volume status and renal monitoring

Estimate blood lossUrine outputHemodynamic stability

Volume status and renal monitoring

Estimate blood lossUrine outputHemodynamic stability

Electrolyte / Metabolic monitoring

Fluid balance Sugar Electrolytes Acid-base balance

Coagulation Monitoring

PT / PTT / INR ACT Platelet counts Factor assays TEG Clinical sign

Temperature monitoring

4 mechanism of heat lossPerioperative hypothermia (BT<36)Core temperature : nasopharynx, esophageal,

tympanic membrane, pulmonary a. catheter, bladder, rectum

Temperature Monitoring

Rationale for use detect/prevent hypothermia monitor deliberate hypothermia adjunct to diagnosing MH monitoring CPB cooling/rewarming

Temperature monitoring

Deleterious effects of hypothermia -cardiac dysrhythmia -increased PVR -Lt. shift of the Oxygen-hemoglobin dissociation curve -reversible coagulopathy (platelet dysfunction) -postoperative protein catabolism and stress response -altered mental status -impaired renal function -decreased drug metabolism -poor wound healing

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