Anesthesia Monitoring ECG PDF

Anesthesia Monitoring: Circulation VETC 2015 Veterinary Anesthesia Laura Couch RVT, MSc, Cardiac Auscultation, One Health (GradCert), Conduction, & BSc...

Anesthesia Monitoring: Circulation VETC 2015 Veterinary Anesthesia Laura Couch RVT, MSc, Cardiac Auscultation, One Health (GradCert), Conduction, & BSc 1 Textbook Anesthesia & Analgesia for Veterinary Technicians Textbook Chapter # 6 Anesthesia & Anesthetic Monitoring Analgesia for Veterinary Indicators of Circulation & Technicians Electrocardiography To keep the patient safe oPages 165 – 187 5th edition oPages 195 – 187 6th edition Continue to introduce why & how we monitor a patient under anesthesia Continue to provide the foundation on how to keep an anesthetized animal safe Objectives Introduce the concepts and devices of this used to monitor circulation & cardiac impulses Lecture Introduce the concepts and devices used to monitor electrocardiography with the electrocardiogram (ECG)  Vital signs groupings:  Circulation  How to monitor?  Heart rate and rhythm, pulse strength, CRT, mucous membrane Monitoring color, blood pressure, and cardiac Patient sounds and impulses/conduction Safety Oxygenation  Mucous membrane color, CRT, hemoglobin saturation, inspired oxygen, arterial blood oxygen  Ventilation  Respiratory rate and depth, breath sounds, end-expired carbon dioxide levels, arterial carbon dioxide, blood pH 5 Instruments Used to Monitor Circulation Heart Rate and Rhythm Esophag Electrocardiogr CRT/ Peripher Echocardiogr Heart eal al Pulse aphy aphy MM Rate stethosc & ope A graphic representation Pulse Amplifies of the Quality heart electrical sounds activity of the heart Used to detect 6 arrhythmias Cardiac Auscultation  Listen to listen? Left, Right, & Sternal (& trachea)!  Watch breathing to distinguish sounds  Palpate pulse while obtaining heart rate from cardiac auscultation  Then listen for at least a minute for an abnormal sounds (whooshes/murmurs, clicks, abnormal pattern)  Heart rates will be more difficult to hear on anesthetized patients  Be patient  Locate the apical pulse to find the loudest sounds  Apical pulse is where you feel the heartbeat through the chest  5th & 6th ribs  Due to reduced cardiac contraction strength (d/t drugs!) 7 Cardiac Auscultation - Videos  Listen on Left, Right, using ABCD locations seen on video https://youtu.be/uLnkf1vBj24?si=eoSmyRmitYgIxNbJ Also good to listen along the ventral aspects (sternum & trachea) To obtain only heart rate best location (loudest) left side 5/6 rib or point of elbow: https://youtu.be/M3DSkG8Yu34?si=CS6axXPHEqXGIoBJ 8  Cardiac Arrhythmias Cardiac Murmurs Common Cardiovasc Hypotension ular Hemorrhage Circulation Hypoxemia Respiratory Arrest Cardiac Arrest 9  Indicators of Circulation: Heart Rhythm ▪ Heart rhythm should be assessed along with heart rate ▪ ALILA Medical Media https://youtu.be/RYZ4daFwMa8?si=MTJxVYEDPRR7QHHa ▪ Cardiac arrhythmias occur commonly in anesthetized animals and vary in significance from innocuous to life-threatening. Therefore the anesthetist must Causes of Arrythmias  Hypoxemia  Hypercapnea  Hypotension  Hypo/Hyperthermia  Electrolyte abnormalities (potassium and magnesium)  Oculo-cardiac reflex  Diseases states or conditions Drugs Inadequate anesthesia / analgesia 11 Cardiac A & P Overview Part 1 Blood Flow Through Heart https://youtu.be/iXgUPwbsWwc?si=CZK0V_7O7lUIV XA3 Part 2 Blood Flow Through Heart Valves https://youtu.be/c5gMMO0wXVY?si=Z5yyHCZmYr6 EWJUu Part 3 Impulses/Conduction Cascade *** https://youtube.com/shorts/hTpkAoT4l84?si=drvkG K7cIX-M0vbB https://youtu.be/lZhTaGDq0T8?si=jtKOG16RdY_ce9 uf Conduction & ECG Production: https://youtu.be/ScZVGHDisa0?si=37Ejn56U6PJR4z 13 Cardiac Conduction System “Type A” Impulses flow from base-to- apex of the heart’s anatomy 14 Depolarization (think contraction) and Repolarization (think Re as in Relax) Resting heart cell state is a negatively charged cell on the inside This is called “polarized” and is impermeable to the +pos ions around it Electrical impulses are generated by automaticity of specialized cardiac cells But when that heart cell gets a zap of electricity it changes to permeable and allows +pos ions in! Na+ rushes into the cell, which causes cell to now have +ve cells inside, AND with pos+ cells on the outside this causes contraction because it is less negative! This is called depolarization This is the firing of the cell After contraction is relaxation: this is where the cells go back to their negative state This is called repolarization when cell returns to negatively charged state Occurs when cell is more permeable to K+ ions leaving the cell causing it to be negatively charged again, leading to muscle relaxation. 15  …Depolarization, Repolarization & Refractory period *can’t fire The cell can’t fire (depolarize/contract) until the cell is in its resting state This is called the refractory period If the animal had a shortened refractory period… the heart muscle could continuously fire This is called fibrillation – an arrythmia It is this depolarization and repolarization process that creates the electrical activity of the heart, which can be represented as the PQRST waveform (“complex”) on an ECG. 16 …Depolarization, Repolarization Video review on this depolarization and repolarization: https://youtu.be/6ulvh_ItKcw?si=lwibdkZ2BSK2kUA- https://youtube.com/shorts/SiQO2ru-5Oc?si=UXQu1We5Y 0aXjIUj 18 19 What is Electrocardiography? (*ECG or EKC)  Diagnostic test that records electrical activity about the heart rhythm in real time  In animals, electrodes may be attached to the limbs, the thorax, and/or other areas (neck, abdominal flanks) to pick up electrical impulses produced by a beating heart  Cardiac electrical impulses (action potentials) originating from the SA node are recorded as voltage (amplitude y-axis) against time x-axis (speed/duration)  Produces the P QRS T waveform  One heartbeat = one ventricular contraction ECG Trace (graph) with Heart Rate (is a calculated number based on highest point of complexes (therefore artifact or irregular rate or rhythm can affect an accurate ECG HR calculation) 21 ECGs can read up to 12 leads  Think of the heart is a 3D structure ECG is reading it as a 2D structure from 12 different angels  think of each of the 12 leads as different views of the heart We are using a 3 lead set up (with 3 electrodes placed on the animal) 22 For purposes of anesthesia we will use a 3-limb lead set up called Einthoven’s triangle. It will suffice in providing a useful ECG tracing Einthoven’s Triangle is defined as the imaginary triangle comprised by 3 limb leads as follows: Lead I, Lead II, Lead III. Along with the augmented leads (avR, avL, avF) Einthoven’s Triangle: Simplified 3 Limb Leads Einthoven's triangle is an imaginary formation of three limb leads in a triangle used in electrocardiography Leads I, II, & III  one lead” is made from the communication of 2 electrodes 26 Einthoven’s Triangle 3Leads & what they are doing R L (or how they are “viewing” the heart)  Lead I: compares right ‘arm’ to left ‘arm’ RA  LA  right forelimb(-ve) to left forelimb (+ve)  Lead II: : compares right ‘arm’ to left ‘leg’ RA  LL  right forelimb(-ve) to left hindlimb(+ve)  what we need to set machine to  Why? b/c it reps the most natural conduction through the heart and yields the largest complex on the screen  Lead III: : compares left ‘arm’ to left ‘leg’ LA  LL  left forelimb(-ve) to left hindlimb(+ve) 28 Small Animals have “Type A” Conduction  Type A = current flows from base to apex Electrode placed from various angles to “capture” the electrical sign (and strength) Use Lead II in small animals because the electrode are far apart & yields the tallest R wave dogs, cats, avians and other small exotics all have type A conduction 29 Right Arm (RA) Left Arm (LA) Ways to Remember Placement for species with type A conduction: Small Animals: Canine, Feline, Avians, Ferrets, Rodents… Smoke (black) over Fire (red) WHITE ON RIGHT – rhymes right upper quadrant – III forelimb/’arm’ LL for LEFT LEG - alliteration Red on left hindleg OR you read book/newspaper with hands (upper) & 31 4 Electrodes & Lead Placement “ink on paper, balls on trees, in right lateral recumbency”  Patient is in n right lateral recumbency for a 4 electrode set up (4th is green), therefore right legs are on the ground/botton  i.e., so assume bottom/on top means above  Ink on Paper  black upper quadrant on top of white right upper quadrant  Red Ornamental Balls on Green Christmas Tree Red balls on top of green tree on green xmas trees  5 leads? Brown electrode goes on apex of 32  3 electrodes most common - black, white, & red * USED in Lab  i.e., x2 electrodes = 1 lead  4 electrodes have a green electrode, in addition to the black, white, & red. In photo above: A 33  Clip Types Clip Types: Atraumatic (crocodile) flat clips (upper right) when anesthetized – not alligator clips (D) which can cause skin trauma if left on too long – both require gel or alcohol  Clip Type: Red dots with snap clips (A) best for patient comfort, place patch on paw pads or hairless area – shave if needed 34  ECG Tech Tips  In addition to snaps/patches (red dots) and clips, needles placed SQ can be utilized for very small patients with the clips attaches to them 35  ECG Settings  Find the menu or settings for your ECG module and adjust to ensure complete is large but not so large it is off the screen - use sizing (“gain”)  Set to Lead II  Okay to change leads to look at other “views” to troubleshoot 36  ECG Tech Tips  Learn how to obtain the best ECG under normal & varying conditions  Aim for steady baseline, artifact free, and print worth tracing that can be interpreted (breathing and movement most common artifacts)  Know your machine and ECG settings (speed, sensitivity, size, lead #…)  Ground your equipment to reduce interference  Ensure wires are not twisted, bent, or touching other electrical equipment Ensure all connections are tight on each electrode and cord  Coil cords loosely, keep dry and clean  Know limitations of an ECG 37 Looking @ an ECG Rhythm Know: what a normal P QRS T complex looks like, troubleshoot lead placement, machine settings, and alert RVT/DVM if needed Can be complex, various methods to simplify  Keep simple until you have a good foundation For anesthesia monitoring patient body position does not matter – Electrode placement & leads matter!  Electrodes must contact skin and use electrode (ECG gel) paste, saline, or alcohol but for anesthesia gel is ideal  Must shave if using red dots or place them on a paw pad so that gel (opposite side of the button) is in contact with skin/pad 38 Textbook Reference PLEASE REVIEW! How to place electrodes page 168 box 6-1  How it print an ECG strip (recording an ECG) page 170 box 6-2 Coming up:  How to determine heart rate from ECG strip, 2 methods, page 173 box 6-4  How to interpret with questions pages 173-174 39 Breakdown P QRS T P Wave  Atrial muscle depolarization = atria's contractions QRS  Ventricular muscle depolarization = ventricles contracting  *think of how QRS looks like a V or Inverted V to help you remember V for Ventricles T Wave  Ventricular muscle repolarization = ventricles relaxing (resting)  Artial repolarization does occur (it has to) but it is hidden in the QRS complex 41  EXTRA - Brea Complex kdown of the P QR ST  P-R interval – The electrical impulse slowly passes through the atrioventricular (AV) node to allow for coordinated ventricular contraction. No myocardium is depolarized at this point, so the ECG trace goes back to baseline. Q wave – Early impulses pass through the AV node via the left bundle branch. There is a small deflection on the ECG trace, as depolarization moves from left to right across the intraventricular septum. R wave – The His-Purkinje fiber network is fully activated by the impulse, which depolarizes the ventricles simultaneously. This is the largest muscle movement and is reflected as the largest wave on the ECG trace. S wave – Finally, the basal parts of the ventricular walls are depolarized. S-T segment -The complex returns to baseline. T wave – The ventricles repolarize, or relax, ready for the next contraction. 42 Speed is the horizontal axis (x)  adjustable durations to 50mm/s or 25mm/s Amplitude is the vertical axis (y)  adjustable sensitivity/voltage mV 43 ECG Questions to ask when evaluating 1. What is the heart rate?  bpm? fast, slow, or normal 2. Are there P waves? Is there a P wave for every QRS wave, a is there a QRS wave for every P wave? (every complex should have a P wave and a QRS wave) 3. What is the QRS Morphology? Is it wide and or bazar? (R wave should be tall and narrow) 4. Are the P-R intervals normal in duration and the same? Vary or constant? 5. Are the R-R intervals the same? Regular or irregular? Goal is to explore the relationships and arrangements of the waveform 44 45 46  Normal Sinus Rhythm Dog (top) vs Cat (bottom) 47  ECG: Sinus Arrhythmia Commonly Encountered Sinus Arrhythmia  Heart rate coordinated with respirations  Decreases during expiration  Increases during inspiration  Normal in dogs, horses, and cattle  Abnormal in cats  HR slows down during an exhalation Does the rate and pattern match the breathing pattern? Be patient, watch & listen Confirm with ECG 48 Sinus Arrhythmia 49  Sinus Arrythmia vs Something else an SA would have a cyclic an SA would have The anesthetist decrease in rate a cyclic increase in can differentiate during rate during SA from an expiration and expiration and abnormal rhythm increase in rate decrease in rate because: during during inspiration. inspiration. Corr ect it is not important it is impossible to to differentiate determine without between the two an ECG. rhythms 50  Other Commonly Encountered Cardiac Arrhythmias Sinus Bradycardia  Abnormally slow heart rate  Common during anesthesia: excessive anesthetic depth and drug reactions  Correct with reversal agents or anticholinergics Sinus Bradycardia Causes  Depressant effect of most anesthetics  Alpha2-agonists and opioids  Excessive anesthesia depth  Adverse effects of drugs 51 52  Other Commonly Encountered Cardiac Arrhythmias Sinus tachycardia  Abnormally fast heart rate  Inadequate anesthetic depth, drug reactions, surgical stimulation  Treat according to cause Tachycardia Causes  Anticholinergics and cyclohexamines  Inadequate anesthetic depth  Pain  Hypotension, Blood loss, Shock  Low O2 (Hypoxemia), High CO2 (Hypercapnea) 53 54  Key Points Proper ECG Know what ECG Lead II electrode normal looks setting on placement like machine for SA Keep Leads Electrode gel Reduce clean, and may absorb interference loosely coiled overtime, may and artifacts need to re Keep tangle free at all times apply 55  Key Points Monitoring equipment, although not mandatory for effective patient monitoring, generates data (including oxygen saturation, arterial blood pressure, cardiac electrical activity, inspired and expired CO2 levels, blood gases, heart rate [HR], respiratory rate [RR], and tidal volume [VT]) that help the anesthetist accurately assess patient status. This equipment often warns of impending problems early, so that the anesthetist can take action before they reach crisis level. Effective monitoring requires the anesthetist to memorize normal monitoring parameters and to know what levels signal a need to inform the attending veterinarian. 56