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
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