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Anesthesia Monitoring By David Roy Godden, MSN CRNA Keck School of Medicine Objectives • • • • • • • • Review need for monitoring List the essential monitors for general anesthesia Identify the most essential monitor in the OR. Describe the indications contraindications for arterial line placement Identify the techniques for arterial line placement. List the complications of arterial line placement and describe trouble shooting arterial line tracings Be able to evaluate an arterial line tracing. Know what the best monitor in the OR is! Objectives • Describe the indications/contraindications for central line placement • Identify the techniques for central line placement. • List the complications of central line placement and trouble shooting CVP waveform • Be able to evaluate the CVP tracing. • Discuss the BIS monitor and be able to discuss patient awareness during anesthesia. Why Monitoring • Monitoring 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 Monitor • Standard 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 cont • Every 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 pt’s temperature must be AVAILABLE. When changes in a pt’s temperature is required or anticipated the continuous measurement and recording of temperature should be done. The Five Alarms • During routine anesthesia care a minimum of 5 alarms must be in use. • Inspired oxygen and a low O2 limit alarm • Airway pressure limit alarm • Oximetry • Blood pressure limit alarm • Heart 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 Monitor • Any 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 Lines • Indications for arterial line placement include: – The need to continuously monitor a pts blood pressure – In ASA class III or IV patient (relative indication) or “sick” patients – When frequent blood draws are anticipated – When ABG evaluation in required – Expected blood loss is high or the need to monitor Hct with expected blood administration – Vascular cases or cases when a hypotensive technique is used – If continuous vasoactive medications are required Contraindications to Art Line • Patient refusal? Discuss options with patient. • Selection of cannulation site requires attention • Choice 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 don’t go there • Ischemia in an extremity with inadequate blood flow • Large thrombus at chosen entry site • What is the Allen’s test? Radial Artery Cannulation • The Allen’s Test do we routinely use it? • In the past the patency of the ulnar artery circulation by the performance of the Allen’s Test has been recommended before cannulation • The Allen’s 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 Allen’s Test in assessing adequacy of the collateral circulation has NOT been confirmed. Allen’s Test • The arteries of the hand, both the radial and ulnar, have collateral circulation • The predominant circulation of the hand is supplied by the ulnar artery in most patients Arteries of the Arm • Note brachial artery small collaterals • Radial is larger and more superficial artery than Ulnar NIBP vs. Arterial Cannulation • NIBP (auscultatory / oscillometric) • Pros – Healthy patients – Short case • Cons – Bladder cuff size – Flow dependent – Motion – Interruption of IV infusion – Injury – Cuff deflation rate – Hydrostatic errors • Arterial Cannulation • Pros – Continuous BP – Sick patients – Difficult cases – ABG monitoring • Cons – Nerve dysfunction – Thrombosis / Ischemia – Hematoma formation – Infection – Hydrostatic errors Art Line Placement Techniques • Sterile prep and sterile towel. Wash hands vs. Surgical scrub and the use of sterile gloves always • Betadyne vs Chloroprep for skin preparation • Dr. Sven-Ivar Seldinger (1921-1998) developed a technique for arterial or venous cannulation • IV method is very slick. Watch Kari Cole or Terrie Norris they are great with this technique me I’m lame. • Arrow Kit is in cart. This technique uses a very sharp needle and soft cannula which is best for longer term use Seldinger Technique • Dr. Sven-Ivar Seldinger (1921-1998) • Use 20 ga needle/cannula to transect artery • Remove needle and then • Draw cannula back slowly till free flow of arterial blood occurs • Pass wire into artery down needle • Thread cannula over the wire. • Easiest method. Art Line Complications • • • • • • • • Thrombus formation Arterial laceration Hematoma Loss of distal perfusion to hand…ouch! Nerve dysfunction from dissection Infection Errors in monitoring Failed attempt. Always consider failure as a potential complication. Arterial Waveform Evaluation • Tf – Foot – Onset of ejection – Systole • T1 - First Shoulder – Peak flow • T2 - Second Shoulder – Peak pressure • • • • • • Ti – dichotic notch End of ejection Closure of aortic valve Precedes the onset of diastole Tt – Pulse Duration Arterial Waveform Shapes • Rate of upstroke – Indicates contractility • Rate of downstroke – Indicates peripheral vascular resistance • Variations in size during respiration – Suggest hypovolemia • Mean arterial pressure – Calculated by integrating the area under the pressure curve Arterial Line Tracing Waveforms • Dynamics of pulsatile flow • Acceleration and deceleration of blood • Elasticity of the artery • Modulated impedance • Paradox (aortadistal arteries) Mean arterial pressure decreases systolic pressure increases • Systolic amplification is particularly apparent in noncompliant arteries Patient Positioning • Radial - 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 Time 10 minutes or so Central Line Indications • Peripheral venous access is required for: – Administration of fluids – Administration of drugs • Central venous access is required for: – Parenteral nutrition – Anticipated Inotropic medication infusion – Anticipated large volume resuscitation – Monitoring of central venous pressure (CVP) – Cardiac pacing – Difficult peripheral access Central Line Contraindications • • • • • • • Patient refusal? Severe Coagulopathy Bundle Branch Blocks relative contraindication Infection at site Previous failed attempts at specific site Hematoma Unusual anatomy Central Line Techniques • Sterile techniques should be used for all central line cannulation • Surgical scrub with Sterile gown and gloves • Sterile prep of skin and surgical drapes. • Local anesthetic should be used for central catheters in awake patients • Success may be improved by using ultrasound guidance • Techniques of gaining access include: – – – – Catheter over needle Catheter through needle Seldinger technique Surgical 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 needle • A soft tipped guide wire is passed through the needle and the needle removed • A dilator is passed over the guide wire • Dilator is removed and catheter is passed over wire and wire is removed • Chest x-ray should be performed to check position of catheter Anatomy of Central Assess • Internal jugular vein – – – – Right sided access preferred. Why? Apical pleura does not rise as high on right and avoids thoracic duct Patient positioned head down In the low approach triangle formed by two heads of sternomastoid and clavicle identified – Cannula aimed down and lateral towards ipsilateral nipple • Subclavian vein – – – – – – Usually approached from below clavicle Patient positioned head down Needle inserted below junction of medial 2/3 and lateral 1/3 of the clavicle Needle aimed towards suprasternal notch Passes immediately behind clavicle Vein 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 Analysis • Cannon Arterial Wave • Cannon "a" waves are abnormalities in the a wave that occur when right atrial contraction takes place against a closed tricuspid valve • Classically 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 lines • Early – Hemorrhage – Air embolus – Pneumothorax – Cardiac arrhythmias – Pericardial tamponade – Failed cannulation • Late – Venous thrombosis – Infection Infection Risks For Central Line • 10% of central lines become colonized with bacteria • 2% of patients in ICU develop catheter-related sepsis • Usually due to coagulase-negative staphylococcus infection • Occasionally due to Candida and Staph. aureus • Infection can be prevented /lessened by aseptic techniques and adequate care of lines • Closed systems should be used at all times • Dedicated lines should be used for parenteral nutrition • Antimicrobial coating of lines may reduce the risk of infection Break Time 10 minutes or so BIS Monitoring • Bispectral Monitoring by Aspect Medical Systems is a non-invasive technology • A 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 BIS • Through 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 BIS • The 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 Anesthesia • Incidence 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 Medicine published 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 Guidelines • The "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 BIS • BIS 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 activity in 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 responses are often mediated at the spinal cord. What is MAC BAR? • BIS enables you to assess consciousness and sedation separately from cardiovascular reactivity How it Works • Raw 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 Savings • See References • Less drug and less overdosing of anesthesia. • Sweet! Faster Wake Ups • BIS-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 time • BIS-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. References • Blitt CD, 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. References • Barish, 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.htm • http://www.cssolutions.biz References Con’t • 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 References • 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. • 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.