Patient Patient MonitoringMonitoring

23 November 200823 November 2008Elvin Cruz, MD, MSElvin Cruz, MD, MS

Med ETT AnesthesiologistMed ETT Anesthesiologist

Roizen: Essence of Anesthesia PracticeStoelting, Miller: Basics of AnesthesiaMorgan, Mikhail: AnesthesiologyFaust: Anesthesiology Review

MonitoringMonitoring

Why monitor vital signs?Why monitor vital signs? ASA standard of care on monitoring ASA standard of care on monitoring

under anesthesiaunder anesthesia NIBPNIBP ECGECG Pulse oximetryPulse oximetry CapnographyCapnography Arterial blood pressureArterial blood pressure

MonitoringMonitoring Data collectionData collection Early warning of adverse changes or Early warning of adverse changes or

trendstrends Response to therapeutic interventionsResponse to therapeutic interventions Reflect proper functioning of other Reflect proper functioning of other

equipmentequipment The most important monitor isThe most important monitor is

YOU, the care providerYOU, the care provider Remain vigilant, integrate monitor Remain vigilant, integrate monitor

information into patient careinformation into patient care

ASA Standards for Basic ASA Standards for Basic Anesthesia MonitoringAnesthesia Monitoring

Applies to ALL anesthetics (GA, MAC, Applies to ALL anesthetics (GA, MAC, Regional)Regional)

Intended to encourage quality patient Intended to encourage quality patient carecare

Can be exceeded at any time based Can be exceeded at any time based on judgmenton judgment

Not intended for OB/pain Not intended for OB/pain managementmanagement

STANDARD ISTANDARD I Qualified anesthesia personnel continuously presentQualified anesthesia personnel continuously present

STANDARD II: Continually evaluateSTANDARD II: Continually evaluate OxygenationOxygenation

Inspired gas: OInspired gas: O22 analyzer with low O analyzer with low O22 alarm* alarm* Blood oxygenation: POx, color assessment*Blood oxygenation: POx, color assessment*

VentilationVentilation Chest excursion, Reservoir breathing bag observation, Chest excursion, Reservoir breathing bag observation,

auscultationauscultation Quantitative ETCOQuantitative ETCO22

Expired volume quantification*Expired volume quantification* ETT/LMA position verified with clinical assessment + ETT/LMA position verified with clinical assessment +

ETCOETCO22

Disconnect alarm when using PPVDisconnect alarm when using PPV

ASA Standards for Basic ASA Standards for Basic Anesthesia MonitoringAnesthesia Monitoring

•Can be waived under extenuating circumstances, document in the medical record record the reason

ASA Standards for Basic ASA Standards for Basic Anesthesia MonitoringAnesthesia Monitoring

Cont. STANDARD II: Continually evaluateCont. STANDARD II: Continually evaluate CirculationCirculation

Continuous ECG*Continuous ECG* NIBP & HR at least every 5 minutes*NIBP & HR at least every 5 minutes* With GA: At least one of theseWith GA: At least one of these

Palpation of pulsePalpation of pulse Heart sounds auscultationHeart sounds auscultation IABPIABP POxPOx US peripheral pulse monitorUS peripheral pulse monitor

TemperatureTemperature Monitor when clinically significant changes Monitor when clinically significant changes

anticipated/expectedanticipated/expected•Can be waived under extenuating circumstances, document in the medical record record the reason

Automated Automated oscillometricoscillometricNIBP monitorNIBP monitor

Non-invasive, automatedNon-invasive, automated Air pump with deflation valve to control Air pump with deflation valve to control

cuff pressurecuff pressure Transducer measures cuff pressure and Transducer measures cuff pressure and

pressure oscillations within the cuffpressure oscillations within the cuff Systolic and MAP correlate well with Systolic and MAP correlate well with

invasive BP measurements, but invasive BP measurements, but diastolic usually 10 mmHg higher with diastolic usually 10 mmHg higher with this methodthis method

Automated oscillometricAutomated oscillometricNIBP monitorNIBP monitor

                                                                              

From: http://egems.gehealthcare.com/geCommunity/monitor/faq_bedside/nbp_faq.jsp

Threshold

Size of cuff influences measurement of BPSize of cuff influences measurement of BP Too small a cuff => Falsely increased BPToo small a cuff => Falsely increased BP Too large a cuff => Falsely decreased BPToo large a cuff => Falsely decreased BP

Loosely wrapped cuff => Falsely increased BPLoosely wrapped cuff => Falsely increased BP Too frequent measurement or wrapped too Too frequent measurement or wrapped too

tight => distal edematight => distal edema To avoid nerve damageTo avoid nerve damage

Avoid applying cuff on bony prominencesAvoid applying cuff on bony prominences Avoid applying cuff across jointsAvoid applying cuff across joints

Select maximum cycle time consistent with Select maximum cycle time consistent with safe monitoringsafe monitoring

Record cuff location and cycle timeRecord cuff location and cycle time Keep ALARMS enabledKeep ALARMS enabled

Automated NIBP monitor Automated NIBP monitor complicationscomplications

ECGECG

Continuous visual displayContinuous visual display Monitors cardiac Monitors cardiac electrical activitieselectrical activities

only, it does not measure heart functiononly, it does not measure heart function Early detection of Early detection of

Dysrhythmias:Dysrhythmias: Lead IILead II

Myocardial ischemia:Myocardial ischemia: Lead V5Lead V5

Electrolyte changesElectrolyte changes Allow calculation of HRAllow calculation of HR

ECGECG

Normal values (adults) :Normal values (adults) : 60 < Pulse < 10060 < Pulse < 100 PR intervalPR interval 0.12 – 0.12 –

0.20 sec0.20 sec QRS durationQRS duration 0.06 – 0.06 –

0.10 sec0.10 sec QT intervalQT interval <= <=

0.40 sec0.40 sec Pulse >100: Pulse >100:

TachycardiaTachycardia Pulse <60: BradycardiaPulse <60: Bradycardia

R-R interval

Normal Sinus rhythmHR ~ 85 bpm

Pulse Rate estimation

HR = 1500/#small boxes in R-R interval

HR = 300/#large boxes in R-R interval

Sinus Tachycardia, HR ~ 135

Sinus Bradycardia, HR ~ 52

Monophasic VT (Ventricular Tachycardia), HR ~ 185

VFib (Ventricular Fibrillation)

AsystoleCheck pulse

Check connectionsVerify other leads

Multifocal PVCs (Premature Ventricular Contractions)

Pulse OximetryPulse Oximetry Practical, non-invasive, reliable monitoring of SpOPractical, non-invasive, reliable monitoring of SpO22 as a as a

reflection of SaOreflection of SaO22

Early warning of arterial hypoxemiaEarly warning of arterial hypoxemia the need for PaOthe need for PaO22 determinations (ABGs) determinations (ABGs) LED measures absorption of specific wavelengths of LED measures absorption of specific wavelengths of

light during arterial pulsationslight during arterial pulsations Computer calculates SpOComputer calculates SpO22

SpOSpO22 > 90% correlates with PaO > 90% correlates with PaO22 > 60 mmHg > 60 mmHg

Alarms for HR, SpOAlarms for HR, SpO22 values values

Acceptable in most cases: 92 <= SpOAcceptable in most cases: 92 <= SpO22 <= 100 <= 100

OO22 supplementation likely needed for SpO supplementation likely needed for SpO22 < 93 < 93

                                                                        

Pulse oximetryPulse oximetry Oxygenated Hgb (HbOOxygenated Hgb (HbO22) and deoxygenatred ) and deoxygenatred

Hgb (Hb) have different optical spectra in Hgb (Hb) have different optical spectra in the 500-1000 nm wavelength rangethe 500-1000 nm wavelength range

Pulse oximetryPulse oximetry How to use:How to use:

Prefer site without arterial catheter, BP cuff, Prefer site without arterial catheter, BP cuff, or IV lineor IV line

Align light source and photodetectorAlign light source and photodetector Move site of reusable sensor every 4 hoursMove site of reusable sensor every 4 hours Check adhesive sensor site for skin integrity Check adhesive sensor site for skin integrity

every 8 hoursevery 8 hours Reusable sensors thoroughly cleaned between Reusable sensors thoroughly cleaned between

patientspatients AdvantagesAdvantages

Continuous monitorContinuous monitor Non-invasiveNon-invasive Early warning of arterial hypoxemiaEarly warning of arterial hypoxemia Monitor pulse rateMonitor pulse rate Decreased need for SaO2 determinations Decreased need for SaO2 determinations

(blood gas)(blood gas)

Pulse Oximetry Pulse Oximetry LimitationsLimitations

Decreased vascular pulsations (Low Decreased vascular pulsations (Low perfusion states)perfusion states) HypotensionHypotension HypothermiaHypothermia VasoconstrictionVasoconstriction

Motion artifactsMotion artifacts ShiveringShivering AgitatedAgitated

Light interferenceLight interference Ambient lightAmbient light Radiant warmersRadiant warmers

Nail polish (especially blue, green, brown)Nail polish (especially blue, green, brown)

Pulse Oximetry Pulse Oximetry LimitationsLimitations

Dysfunctional hemoglobins can be interpreted Dysfunctional hemoglobins can be interpreted as Oxyhemoglobin by the pulse oximeteras Oxyhemoglobin by the pulse oximeter COHgb interpreted as HbOCOHgb interpreted as HbO22 => Falsely high SpO => Falsely high SpO22

MethHgb biases SpOMethHgb biases SpO22 reading towards 85% reading towards 85%

FetalHgb has little influence in SpOFetalHgb has little influence in SpO22

Errors in data interpretationErrors in data interpretation Skin burns in MRISkin burns in MRI TR results in venous pulsations => Falsely TR results in venous pulsations => Falsely

low SpO2, specially with ear probeslow SpO2, specially with ear probes

Pulse Oximetry Pulse Oximetry LimitationsLimitations

Values accurate from 70-100%. Any Values accurate from 70-100%. Any number below 70% is an extrapolation number below 70% is an extrapolation and not very accurate (although less than and not very accurate (although less than 70%).70%).

SpO2 number likely to be inaccurate

CapnographyCapnography Continuous measurement of patient’s inhaled and Continuous measurement of patient’s inhaled and

exhaled [COexhaled [CO22]] Waveform display more informative than the valueWaveform display more informative than the value Useful for evaluation ofUseful for evaluation of

Esophageal intubationEsophageal intubation Disconnect in breathing circuitDisconnect in breathing circuit Rebreathing of CORebreathing of CO22

Cardiac arrestCardiac arrest Malignant Hyperthermia / Thyroid stormMalignant Hyperthermia / Thyroid storm HypotensionHypotension PEPE

ETCOETCO22 underestimates PaCO underestimates PaCO22 due to deadspace due to deadspace ventilationventilation

CapnographyCapnography

Esophageal intubationEsophageal intubation

Inadequate sealInadequate seal

HypoventilationHypoventilation

HyperventilationHyperventilation

Airway obstructionAirway obstruction

Curare cleftCurare cleft

Invasive BPInvasive BPor Arterial or Arterial

Line Line MonitoringMonitoring

Invasive, continuous measurement of Invasive, continuous measurement of arterial BParterial BP

Catheter in a peripheral artery connected Catheter in a peripheral artery connected to a transducer and displayto a transducer and display

Indications:Indications: Expected hemodynamic instabilityExpected hemodynamic instability Rigorous control of blood pressure is Rigorous control of blood pressure is

necessarynecessary Need for analysis of multiple blood gas Need for analysis of multiple blood gas

samplessamples Not indicated for drug administrationNot indicated for drug administration

Arterial Line MonitoringArterial Line Monitoring Technique:Technique:

Sterile prep, glovesSterile prep, gloves Feel pulseFeel pulse 20G catheter for radial artery in adults, 22G in 20G catheter for radial artery in adults, 22G in

pediatricspediatrics Secure with suture and/or clear tape or dressingSecure with suture and/or clear tape or dressing Transducer line with pressure tubing attached to IV Transducer line with pressure tubing attached to IV

fluids on a pressure bag set at 250 mmHg. Transducer fluids on a pressure bag set at 250 mmHg. Transducer setup infuses a few ml of saline into artery every hour setup infuses a few ml of saline into artery every hour to prevent clotting. Non-pressure tubing will dampen to prevent clotting. Non-pressure tubing will dampen signal.signal.

Transducer is zeroed and positioned at the level of the Transducer is zeroed and positioned at the level of the heartheart

Possible complications:Possible complications: Distal ischemiaDistal ischemia InfectionInfection HemorrhageHemorrhage Any air in the line will dampen the signalAny air in the line will dampen the signal

Arterial Line MonitoringArterial Line Monitoring Cannulation site:Cannulation site:

Radial artery – most common siteRadial artery – most common site Femoral arteryFemoral artery Dorsalis pedis Dorsalis pedis Brachial arteryBrachial artery Ulnar arteryUlnar artery Axillary arteryAxillary artery

Site of placement of arterial line catheter Site of placement of arterial line catheter determines the shape of the arterial pressure determines the shape of the arterial pressure wave. The farthest from the heart, the wave. The farthest from the heart, the higher the systolic pressure and the lower higher the systolic pressure and the lower the diastolic pressure. MAP remains about the diastolic pressure. MAP remains about the same at all sitesthe same at all sites

Upon removal of arterial catheter hold Upon removal of arterial catheter hold pressure at insertion site for 3-5 minutes to pressure at insertion site for 3-5 minutes to prevent bleeding/hematomaprevent bleeding/hematoma