Anesthesia MonitoringByDavid Roy Godden, MSN CRNAKeck School of Medicine

ObjectivesReview need for monitoringList the essential monitors for general anesthesiaIdentify the most essential monitor in the OR.Describe the indications contraindications for arterial line placementIdentify the techniques for arterial line placement.List the complications of arterial line placement and describe trouble shooting arterial line tracingsBe able to evaluate an arterial line tracing.Know what the best monitor in the OR is!

ObjectivesDescribe the indications/contraindications for central line placementIdentify the techniques for central line placement.List the complications of central line placement and trouble shooting CVP waveformBe able to evaluate the CVP tracing.Discuss the BIS monitor and be able to discuss patient awareness during anesthesia.

Why MonitoringMonitoring is an essential part of anesthesia care. Effective monitoring reduces the potential for poor outcomes that may follow anesthesia by identifying derangements before they result in serious or irreversible injury (Barish, 2006)Standard I for monitoring includes: 1) the presence of a qualified provider to be present in the operating room at all times to monitor the pt continuously and modify anesthesia care based on clinical observations and responses of the patient to treatments.

What to MonitorStandard II specifies: an oxygen analyzer with a low concentration limit alarm; quantitative assessment of blood oxygenation during anesthesia; continuously ensuring the adequacy of ventilation by physical diagnostic techniques during all anesthesia care. Quantitative monitoring of tidal volume and capnography are encouraged in all pts undergoing GA; Ensuring adequacy of circulation by by a) continuous display of the ECG and b) blood pressure measurements at least Q 5 minutes. Pulse quality via palpation is historically the method for evaluating adequacy of circulation. Radial pulse = MAP>60 or so while femoral pulse may be palpated at a lower mean. Pre-cordial stethoscope anyone?

Monitoring contEvery patient that is endotracheal intubated or has an LMA placed requires qualitative identification of carbon dioxide in the expired gas!During GA capnography and end-tidal C02 analysis are encouraged! Really encouraged not required? For Off site anesthesia care NC oxygen with capnography is ENCORAGED STRONGLY! So does every general anesthesia case require an airway? You would think so. Wait till you get the CHLA.Mask Case with general anesthesia require what monitors?During all anesthetics the means for measuring a pts temperature must be AVAILABLE. When changes in a pts temperature is required or anticipated the continuous measurement and recording of temperature should be done.

The Five AlarmsDuring routine anesthesia care a minimum of 5 alarms must be in use.Inspired oxygen and a low O2 limit alarmAirway pressure limit alarmOximetryBlood pressure limit alarmHeart Rate limit alarms.Often too many alarms just cause confuse confusion. When were you last in the ICU with alarms going off continuously? The Pulse Oxygen Tone must be monitored continuously! Make sure that the volume of the tone is adequate for you!

What is the Best Monitor?I want you to think about all of the monitors that you have available and try to decide which is the most useful or most essential to provide safe anesthesia care.Is it the ECG or the Blood Pressure. What about monitoring adequacy of ventilation with capnography?You must decide what is the most essential.What could you do without?Do you consider the pre-cordial stethoscope an essential monitor? If so why? What info does the pre-cordial give you about the patient?

Best MonitorAny biomedical engineer can design more monitors. The list is potentially endless.However nothing replaces the presence of a Vigilant anesthesia provider. You are the Best Monitor of a patients condition during General Anesthesia.Through the use of visualization, palpation and auscultation the anesthetist can monitor the adequacy of circulation, ventilation and temperature. The use of technology increases your ability to do this monitoring quickly and efficiently but none of these advances replace YOU. Be watchful. Pay attention. Look at the Patient.Use the pre-cordial stethoscope! So what's the best monitor?

Arterial LinesIndications for arterial line placement include:The need to continuously monitor a pts blood pressureIn ASA class III or IV patient (relative indication) or sick patientsWhen frequent blood draws are anticipatedWhen ABG evaluation in requiredExpected blood loss is high or the need to monitor Hct with expected blood administrationVascular cases or cases when a hypotensive technique is usedIf continuous vasoactive medications are required

Contraindications to Art LinePatient refusal? Discuss options with patient.Selection of cannulation site requires attentionChoice of site by location. First use radial, then DP (dorsalis pedis), then femoral, lastly brachial. Why?If there is infection at the site of entry then dont go thereIschemia in an extremity with inadequate blood flowLarge thrombus at chosen entry siteWhat is the Allens test?

Radial Artery CannulationThe Allens Test do we routinely use it? In the past the patency of the ulnar artery circulation by the performance of the Allens Test has been recommended before cannulationThe Allens Test is performed by compressing both radial and ulnar arteries while the patient tightens his or her fist. Releasing pressure on each respective artery determines the dominant vessel supplying blood to the hand.The prognostic value of the Allens Test in assessing adequacy of the collateral circulation has NOT been confirmed.

Allens TestThe arteries of the hand, both the radial and ulnar, have collateral circulationThe predominant circulation of the hand is supplied by the ulnar artery in most patients

Arteries of the ArmNote brachial artery small collateralsRadial is larger and more superficial artery than Ulnar

NIBP vs. Arterial CannulationNIBP (auscultatory / oscillometric)ProsHealthy patientsShort caseConsBladder cuff sizeFlow dependentMotionInterruption of IV infusionInjuryCuff deflation rateHydrostatic errorsArterial CannulationProsContinuous BPSick patientsDifficult casesABG monitoringConsNerve dysfunctionThrombosis / IschemiaHematoma formationInfectionHydrostatic errors

Art Line Placement TechniquesSterile prep and sterile towel. Wash hands vs. Surgical scrub and the use of sterile gloves alwaysBetadyne vs Chloroprep for skin preparationDr. Sven-Ivar Seldinger (1921-1998) developed a technique for arterial or venous cannulationIV method is very slick. Watch Kari Cole or Terrie Norris they are great with this technique me Im lame.Arrow Kit is in cart. This technique uses a very sharp needle and soft cannula which is best for longer term use

Seldinger TechniqueDr. Sven-Ivar Seldinger (1921-1998)Use 20 ga needle/cannula to transect arteryRemove needle and thenDraw cannula back slowly till free flow of arterial blood occursPass wire into artery down needleThread cannula over the wire.Easiest method.

Art Line ComplicationsThrombus formationArterial lacerationHematomaLoss of distal perfusion to handouch!Nerve dysfunction from dissectionInfectionErrors in monitoringFailed attempt. Always consider failure as a potential complication.

Arterial Waveform EvaluationTf FootOnset of ejectionSystoleT1 - First ShoulderPeak flowT2 - Second ShoulderPeak pressureTi dichotic notchEnd of ejectionClosure of aortic valvePrecedes the onset ofdiastoleTt Pulse Duration

Arterial Waveform ShapesRate of upstrokeIndicates contractilityRate of downstrokeIndicates peripheral vascular resistanceVariations in size during respirationSuggest hypovolemiaMean arterial pressureCalculated by integrating the area under the pressure curve

Arterial Line Tracing

WaveformsDynamics of pulsatile flowAcceleration and deceleration of bloodElasticity of the arteryModulated impedanceParadox (aortadistal arteries) Mean arterial pressure decreases systolic pressure increasesSystolic amplification is particularly apparent in noncompliant arteries

Patient PositioningRadial - Rotate shoulder by 20-30 degrees, palm upwards and dorsiflex the wrist (a 500ml intravenous fluid bag makes a useful rest) an assistant or adhesive tape can be used to fix the wrist. Femoral - Abduct the leg by 30-40 degrees and externally rotate the hip. Brachial - Fully extend the elbow but avoid hyperextension, an assistant can help maintain elbow extension. Dorsalis Pedis - plantar flex the foot.

Normal Arterial Waveform

Break Time10 minutes or so

Central Line IndicationsPeripheral venous access is required for: Administration of fluidsAdministration of drugsCentral venous access is required for: Parenteral nutritionAnticipated Inotropic medication infusionAnticipated large volume resuscitationMonitoring of central venous pressure (CVP)Cardiac pacingDifficult peripheral access

Central Line ContraindicationsPatient refusal?Severe CoagulopathyBundle Branch Blocks relative contraindicationInfection at sitePrevious failed attempts at specific siteHematomaUnusual anatomy

Central Line TechniquesSterile techniques should be used for all central line cannulationSurgical scrub with Sterile gown and glovesSterile prep of skin and surgical drapes.Local anesthetic should be used for central catheters in awake patientsSuccess may be improved by using ultrasound guidanceTechniques of gaining access include: Catheter over needleCatheter through needleSeldinger techniqueSurgical cut-down is surgical technique as last resort.

Seldinger technique

There are four steps to the Seldinger technique Venous puncture is performed with an introducer needleA soft tipped guide wire is passed through the needle and the needle removedA dilator is passed over the guide wireDilator is removed and catheter is passed over wire and wire is removedChest x-ray should be performed to check position of catheter

Anatomy of Central AssessInternal jugular vein Right sided access preferred. Why?Apical pleura does not rise as high on right and avoids thoracic ductPatient positioned head downIn the low approach triangle formed by two heads of sternomastoid and clavicle identifiedCannula aimed down and lateral towards ipsilateral nippleSubclavian vein Usually approached from below claviclePatient positioned head downNeedle inserted below junction of medial 2/3 and lateral 1/3 of the clavicleNeedle aimed towards suprasternal notchPasses immediately behind clavicleVein encountered after 4-5 cm

Normal CVP Waveform

Waveform Interpretation+ a wave : This wave is due to the increased atrial pressure during right atrial contraction. It correlates with the P wave on an EKG.+ c wave : This wave is caused by a slight elevation of the tricuspid valve into the right atrium during early ventricular contraction. It correlates with the end of the QRS segment on an EKG.- x descent : This wave is probably caused by the downward movement of the ventricle during systolic contraction. It occurs before the T wave on an EKG.

Waveform Interpretation+ v wave : This wave arises from the pressure produced when the blood filling the right atrium comes up against a closed tricuspid valve. It occurs as the T wave is ending on an EKG.-y descent : This wave is produced by the tricuspid valve opening in diastole with blood flowing into the right ventricle. It occurs before the P wave on an EKG.

Cannon A Waves

A Waveform AnalysisCannon Arterial WaveCannon "a" waves are abnormalities in the a wave that occur when right atrial contraction takes place against a closed tricuspid valveClassically occurs in 3rd degree heart block or AV dissociation.Unlike giant "a" waves, which are uniform in height and are observed during each cardiac cycle, cannon "a" waves are variable in height and occur sporadically because of the variable relationship of atrial contraction to ventricular systole.

Complications Central linesEarlyHemorrhageAir embolusPneumothoraxCardiac arrhythmiasPericardial tamponadeFailed cannulationLateVenous thrombosisInfection

Infection Risks For Central Line10% of central lines become colonized with bacteria2% of patients in ICU develop catheter-related sepsisUsually due to coagulase-negative staphylococcus infectionOccasionally due to Candida and Staph. aureusInfection can be prevented /lessened by aseptic techniques and adequate care of linesClosed systems should be used at all timesDedicated lines should be used for parenteral nutritionAntimicrobial coating of lines may reduce the risk of infection

Break Time10 minutes or so

BIS MonitoringBispectral Monitoring by Aspect Medical Systems is a non-invasive technologyA BIS sensor is placed on your forehead and then connected through a cable to a monitor. Together the sensor and monitor measures your brain activity and then computes a number between 0 and 100 which corresponds to your level of consciousness.So What you say.

What is the BISThrough BIS technology, we may have a better understanding of the human brain.The BIS technology measures the effects of drugs on the brain; a previously unknown element of patient status. BIS technology is widely studied, and widely accepted, and is supported by more than 2500 published studies.

More About the BISThe technology has been used on more than 15.2 million patients around the world, and is utilized in more than 70% of the top-ranked US hospitals (according to a 2005 US News and World Report ranking). What's the Big Deal?It costs about 15 dollars per BIS strip. Is it worth it and how does it help me?

Awareness Under AnesthesiaIncidence and adverse outcomes of awareness with recall in adults should be part of your post op assessment.Research demonstrates that awareness with recall occurs in one to two patients per thousand receiving general anesthesia. Historically in trauma and cardiac surgical patients mostly.Prospective research shows that approximately 50% of patients that experience awareness with recall suffer psychological problems. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) issued a Sentinel Event Alert on preventing and managing the impact of anesthesia awareness.

Recent Article NEJM

The New England Journal of Medicinepublished a study that concludes that the Aspect Medical BIS Monitor is no more effective than older products at preventing anesthesia awareness.Really does it matter? I will say no because of all of the other things the BIS monitor does.

Practice GuidelinesThe "Practice Advisory for Intraoperative Awareness and Brain Function Monitoring" published in 2006 describes using multiple monitoring modalities "clinical techniques, conventional monitoring and brain function monitoring" to assess anesthetic depth and reduce the likelihood of intraoperative awareness. The Practice Advisory consensus opinion was that "the decision to use a brain function monitor should be made on a case-by-case basis by the individual practitioner for selected patients."

Bottom Line with the BISBIS can help clarify the distinction between brain and spinal cord responses, enabling you to manage anesthetic goals of hypnosis, analgesia and immobility Because BIS measures electrical activityin the brain, it provides a direct correlation with depth of consciousness (hypnosis) Responses to surgical stimulation are frequently indicators of the need for additional analgesia.These responsesare often mediated at the spinal cord. What is MAC BAR?BIS enables you to assess consciousness and sedation separately from cardiovascular reactivity

How it WorksRaw EEG information is obtained via a sensor placed on patient's forehead currently left or right brain monitoring.The BIS system processes the EEG information and calculates a number between 0 and 100 that provides a direct measure of the patient's level of consciousness A BIS value near 100 indicates the patient is fully awake. I took a BIS reading off of a freshly pronounced body and the BIS reading was 53!A BIS value of zero indicates the absence of brain activity

Drug SavingsSee ReferencesLess drug and less overdosing of anesthesia.Sweet!

Faster Wake UpsBIS-monitored patients wake up faster, are extubated sooner, and are more oriented upon arrival to the PACU. Use of the BIS for wake up is awesome!

PACU discharge timeBIS-monitored patients have been shown to be eligible for PACU discharge 16% sooner. I am on retainer at the Aspect Medical Corp. Just a little joke.

ReferencesBlittCD, Hines HL.Monitoring in Anesthesia and Critical Care Medicine. New York: Churchill Livingstone, 1995.Costanzo, L. Board Review Series: Physiology. Baltimore : Lipincott Williams and Wilkins, 1998.Miller Anesthesia, 5th ed., Churchill Livingstone, Inc, 2000.Mikhail M, Morgan GE, Murray MJ. Clinical Anesthesiology, third edition. New York : McGraw Hill, 2002.

ReferencesBarish, P., et al. Clinical Anesthesia. Third ed. Philadelphia:Lippencott, 1997. (626-629)Marino, D. The ICU Book. Second ed. New York: LippincottWilliams & Wilkins, 1998. (143-153)Miller, R., et al. Anesthesia. Fourth ed, Vol.1. New York: Churchill-Livingstone, 1994. (1166-1169)Morgan, G., et al. Clinical Anesthesiology. Third ed. San Francisco:Lange, 2002. (91-97)http://hemodynamics.ucdavis.edu/mustafa/Pulse.htmhttp://www.cssolutions.biz

References Cont New England Jounal Of Med, Anesthesia Awareness and the Bispectral Index Volume 358:1097-1108 Sandin R, Enlund G. Awareness during anesthesia: a prospective case study. The Lancet 2000; Vol 355. Myles P, Williams D. Patient satisfaction after anaesthesia and surgery: results of a prospective survey of 10,811 patients. British Journal of Anaesthesia 2000; 84 (1). Luginbuhl M, Schnider TW. Detection of awareness with the Bispectral Index: two case reports. Anesthesiology 2002; 96 (1): 241-243.

More ReferencesGan TJ, Glass PS, Windsor A, Payne F, Rosow C, Sebel P, Manberg P, and the BIS Utility Study Group. Bispectral Index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. Anesthesiology 1997; 87 (4): 808-815. Mayfield JB, Quigley JD. BIS monitoring reduces phase I PACU admissions in an ambulatory surgical unit (ASU). Anesthesiology 1999; 91 (3A): A28. Gan TJ, Glass PS, Windsor A, Payne F, Rosow C, Sebel P, Manberg P, and the BIS Utility Study Group. Bispectral Index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. Anesthesiology 1997; 87 (4): 808-815.