Veterinary CPR (PDF)

Cardiopulmonary resuscitation CP3.14 Supporting the patient Pamela Murison1 2023-24 2 Year ILOs CP3011 Explain the aetiology, pathophysiology & epidemiology of conditions of veterinary interest that require emergency treatment (e.g. pain, shock, trauma & poisoning) CP3024(b) Formulate a therape...

Cardiopulmonary resuscitation CP3.14 Supporting the patient Pamela Murison1 2023-24 2 Year ILOs CP3011 Explain the aetiology, pathophysiology & epidemiology of conditions of veterinary interest that require emergency treatment (e.g. pain, shock, trauma & poisoning) CP3024(b) Formulate a therapeutic plan to treat/manage common veterinary emergencies, demonstrating an understanding of the underpinning science principles. 3 Lecture ILOs      List possible causes of cardiopulmonary arrest (CPA) Describe the signs of CPA Describe actions to be taken in basic and advanced cardiac life support Select appropriate cardiac compressions for different animals Indicate the likelihood of success with CPR in small animals 4 Cardiopulmonary arrest ….the sudden cessation of functional ventilation and effective circulation 5 Signs of arrest      No heart sounds ECG shows asystole or arrhythmia No palpable pulse Apnoea, or jerky gasping breathing Blood looks thick, dark and is not flowing freely      Mucous membrane colour Prolonged CRT No cranial nerve reflexes Eye central with a dilated pupil Dry cornea 6 Causes of arrest   Myocardial Hypoxia Toxins –   pH extremes Electrolyte imbalance –  Includes anaesthetics! e.g. Inc potassium Temperature extremes     hypoxaemia / hypercapnia pre-existing cardiac disease acute hypotension vagal reflexes (e.g. traction on extra-ocular muscles, during enucleation) 7 Resuscitation   Only really successful if cause treatable To what extent will you resuscitate? 8 Cardiopulmonary Resuscitation (CPR) REMEMBER YOUR A-B-C A = Airway B = Breathing C = Circulation D = Drugs E = Electrical defibrillation/ECG F = Follow-up Basic life support Advanced life support 9 CPR management  Time is of the essence! 10 A = Airway   Check for physical obstruction Endotracheal intubation – If not possible, use narrow catheter or tracheostomy 11 B = Breathing      IPPV Pref 100% O2 Approx 10 breaths per minute Watch chest rise Allow adequate time for deflation 12 C = Circulation    Check pulses/heart sounds ASAP Monitor these continuously Maintain continuous compressions 13 External cardiac compressions: Cardiac pump      Small dogs, narrow chested breeds Right lateral recumbency Compress 3rd-6th Intercostal space Use sandbag under chest if necessary Rate approx 100-120 14 External cardiac compressions: Cardiac pump     Cats, tiny dogs Finger and thumb across heart Compress Rate = 100-120 minute 15 External cardiac compressions: Cardiac pump    For large, barrel chested breeds ‘thoracic pump’ Compress over highest point of thorax Picture: D Flaherty Picture credit: vet.cornell.edu 16 How does compression produce output? Cardiac pump – Indirect compression of heart Thoracic pump     chest compression   intrathoracic pressure  intrathoracic pressure  pressure on outside of heart, lungs and great vessels  blood to flow forward in arteries and backwards in veins backward flow is minimised by venous valves/collapse 17 Choosing technique    Cats/dogs under 15kg Dogs over 15 kg Except sighthound type build By Neurodoc - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2534945 18 Successful external compressions      Rate: 100-120/min Table position Compress approx. 1/3 of thorax Allow adequate time to fully recoil Change staff frequently Picture: D Flaherty 19 Internal cardiac compressions       Rapid clip (3-6 IC spaces) In expiration, incise 5th interspace Locate by using olecranon to point Open pleura and pericardium Milk ventricles into arteries Continue ventilation 20 21  ICC preferred if – Thorax already open – Large dogs, ECC less likely to be effective – Disease processes mean ECC unlikely to be effective (e.g. rib fractures, pleural effusion, diaphragmatic rupture etc) – If ECC ineffective – May be suitable to enter via diaphragm 22 Circulation    If hypovolaemia preceded arrest, ensure rapid IV fluids Some fluid can help push drugs to central circulation Rapid fluids not suitable for all cases 23 Drugs   Most effective route via central /jugular injection Peripheral injection may not reach heart – –  Intracardiac effective if administered properly – –  But risk of myocardial injection/damage Avoid unless open thorax Transtracheal requires high doses of drugs – –  Commonly used Flush saline after drug Min 2 x dose of atropine or adrenaline Not suitable for other drugs Intraosseous may be suitable e.g. exotics 24 Drugs     Adrenaline (epinephrine) Atropine Lidocaine Vasopressin? Use Dose (mg/kg, IV) Adrenaline In asystole, to coarsen ‘fine’ VF, increase inotropy and systemic vascular resistance 0.01 (high dose of 0.1 has been used esp after prolonged CPR) Atropine For atrioventricular block, asystole which has been preceded by bradycardia (vagus mediated) 0.04 Lidocaine Ventricular arrhythmias 2-4 (as a bolus) 25-75 microgram/kg/min infusion 25 ECG   Monitor an ECG if available Determine arrest rhythm – Asystole – Ventricular fibrillation – (Ventricular tachycardia) – Pulseless electrical activity 26 Arrest rhythms Asystole Ventricular fibrillation Coarse Picture: D Flaherty Pulseless electrical activity (PEA) [Electromechanical dissociation] Fine Picture: D Flaherty 27 Is it an arrest rhythm? Ventricular tachycardia Pulseless ventricular tachycardia Picture: D Flaherty 28 Electrical defibrillation   Used extensively in people Less likely to be effective in asystole or PEA 29 Electrical defibrillation        Charge Apply conducting gel to paddles and dog Current applied across heart STAND CLEAR 1-5 joules/kg external 0.1-0.5 joules per/kg if using internal paddles (if monophasic upper end of range, biphasic lower end of range) 30 31 Follow-up      Fluids Ensure renal perfusion (urine production) Warmth (caution) Analgesics May need other drugs to support (e.g. dopamine) 32 Signs of effective CPR      Palpable pulse during cardiac compression Retinal blood flow (as detected by using a Doppler probe on the cornea) Carbon dioxide detectable on capnography Improvement in colour of mucous membranes ECG changes 33 Signs of effective CPR- recovery      Lacrimation Pupillary constriction Return of cranial nerve reflexes Return of other neurological function- e.g. response to sound, righting reflexes etc. Return of spontaneous ventilation 34 When should you give up? 35 Equipment   Keep crash kit handy Well stocked and checked frequently 36 Actions during an arrest ?C-A-B Ideally 3-4 people 1) Directing situation, making decisions, assessing patient 2) Compressions 3) Ventilation 4) Drawing up drugs, attaching ECG, keeping records (Person performing compressions can tire) Prioritise chest compressions if only one person 37 Survival after CPR  Kass and Haskins (1992) reported a 1 week survival rate of <4% in dogs and cats that required CPR –  ALL survivors in this study arrested subsequent to anaesthesia/drugs Hofmeister et al. (2009) reported 35% of dogs and 44% of cats had successful CPR – 6% animals survived to discharge 38 39 Further information  RECOVER http://acvecc-recover.org/  New guidelines in preparation Fletcher et al. RECOVER evidence and knowledge gap analysis on veterinary CPR. Part 7: Clinical guidelines Journal of Veterinary Emergency and Critical Care (2012), 22, S102-S131