Post Anesthetic Complications with the Small Animal Patient

Andrew Claude DVM DACVAA Assoc. Professor and Service Chief, Michigan State University College of Veterinary Medicine [email protected] Goals

• Definition of anesthetic recovery • Hastening and delaying anesthetic recovery • Patient during anesthetic recovery • When to extubate and/or reintubate • Brachycephalic breeds and other conditions that influence recovery • Common and less common challenges that occur during anesthetic recovery and how to mitigate. • Animal welfare topics Anesthetic “Recovery”

• What is anesthetic recovery? • Veterinary patients • Regains swallow/gag reflex, remain sternal (ability to right his/herself? • Ability to ambulate • Factors influencing the length of anesthetic recovery • Is post-op, anesthetic recovery really a concern? • Greater than half canine and feline anesthetic related mortality occur during recovery. (Brodbelt et. al. Confidential inquiry reports, 2007, BJVA) • Thorough planning and anticipate problems before, during and after . • Keep good anesthetic records for pre, intra and post-anesthetic periods. Anesthetic records and patient monitoring

• Anesthesia records are legal documents. • Never assume, always protect yourself with complete records • Record all drugs and amounts given in mgs or mcgs • Record ALL events including adversities/complications • Complete chronological record of anesthetic event • One person dedicated to patient monitoring; pre, intra, & post • Signed by the veterinarian Anesthetic recovery

• Elimination of anesthetic inhalant agents follow opposite PKs as uptake. • During induction patients go through stages 1 and 2. Prefer they reside in stage 3 anesthesia (surgical plane) • During recovery they reverse steadily to a conscious state through the planes of anesthesia. • Inhalant anesthetics are off-loaded by reversing concentration gradient from patient to the machine (scavenging). • Hastened engaging flush valve • Injectable anesthetics can be reversed, if possible or if necessary. Post-anesthetic patient monitoring

• Anesthetic patient monitoring should NOT end when anesthetics are turned off. • How long should monitoring continue? • What parameters should be monitored? • What about and monitoring analgesia? • Post anesthetic patient monitoring should be recorded. • Veterinary patients recovering from anesthesia should never be left alone

Intubation and extubation

• Is intubation always necessary? • Aspiration • Secured airway • Ventilation • Clinical signs indicating return of laryngeal and pharyngeal reflexes • What is the “gag” reflex? • CN IX (glossopharyngeal) • CN X (vagal) • Can the ET tube be removed too early? Too late? • When is the ideal time to extubate? • “normal” breeds • Brachycephalic breeds • Cats • Concerns after extubation?

Brachycephalic breeds

• Common breeds • English Bulldogs • French Bulldogs • Pugs • Boston Terriers • Brachycephalic syndrome • Worse case of sleep apnea ever seen!! • Pre-anesthetic considerations • Post- anesthetic considerations • Never leave unattended when sedated • What do you do if brachycephalic patient obstructs? • Pre/post-anesthetic oxygenation When should we extubate?? Anesthetic recovery: MDR mutation

• MDR1 mutation (Multi-Drug Resist) • Breeds associated American Kennel Club • Defect of BBB ability transport • Herding breeds drugs out of the brain • Collies, esp. Border Collie • P-Glycoprotein • Australian Shepherds • Site hounds • Higher incidences of pre- • Whippet (long-haired) anesthetic and post-anesthetic • Windhounds opioid dysphoria/excessive • German and English Shepherds response • Can be reversed • Anesthetic drugs • Butorphanol • Lower doses, other options • Morphine • Acepromazine Post-anesthetic feline blindness/deafness

• Canine 2 blood supplies to brain • Internal carotid • Basilar artery • Cats one blood supply to brain • Maxillary artery • Options

• Use nothing Barton –Lamb et. al. 2013 • Play-doh needle cap Supplemental O2

• Supplemental O2 pre-anesthetic • Oxygen dependent patients • Brachycephalic breeds medicalplus-vet.com • Benefits of supplemental O2 during anesthetic recovery. • How much and how long to supplement. • Considerations for normal vs. sick (pulmonary) patients. • Obese • Pregnant • Brachycephalic Anesthetic recovery: patient welfare • Definition of “patient welfare” • Analgesia • Canine Glasgow pain score (short form) • Feline Glasgow pain score (Feline Grimace Score) • Preventive analgesia vs. pre-emptive analgesia • Pre-emptive • Intra-operative • Post-operative *** • When in doubt treat for pain • Patient comfort • Body temperature • Bedding • Having personnel with the patient during recovery • Physical contact • Soothing voice Patient Welfare

Anesthetic recovery: vomiting &/or regurgitation

• Vomiting more commonly during pre-op sedation. • Opioids (Hyrdomorphone, morphine) w/ dogs • Alpha 2 agonists (Xylazine) cats • Maropitant and/or ondansetron • Intra-op regurgitation is common • Most often silent regurgitation • What are the problems? • How to handle the situation? • ET tube cuff pressures • Salem Sump tubes/saline • Post-op vomiting and/or regurgitation • Ability to guard airway/swallow less risk of aspiration and/or esophageal damage • If patient is still very sedated; Re-anesthetize, clean, re-intubate and flush? Anesthetic recovery: slowing it down

• Emergence delirium • Stage 2 anesthesia • Dysphoria • Pain • Discomfort Anesthetic recovery: ROUGH!!

• Delirium vs. dysphoria vs. something else….? • Differs between dogs and cats • Emergence delirium • Conscious • Unconscious (Stage 2 anesthesia) • Pain • Analgesics • Dysphoria • Opioids • Other drugs • Other • Bladder full? • Hungry? Pet MD Anesthetic-related hypothermia

• Number one adverse consequence of anesthesia • Causes of hypothermia intra and post-anesthetic • Hypothermia results in multiple complications • Bradycardia • Delayed recovery • Post-anesthetic shivering • Coagulopathies • Catecholamine release • Increase stress • Mitigating hypothermia • Maintaining body temps during anesthesia • Above 97* • Heating sources Anesthetic-related hyperthermia • Uncommon in small animal anesthesia • -like syndrome • Site hounds (grey hounds) • Labrador Retrievers • Most commonly due to fever and/or iatrogenic • Feline post-anesthetic hyperthermia • Opioid hysteria and hyperthermia in cats • • Treatment • MH • Cooling techniques

Pinterest Post-operative airway obstruction

• Some patients have higher chances of post- anesthetic obstruction Double whammy! • Brachycephalic breeds • Overweight, obese patients • Pharyngeal, laryngeal etc. surgeries. • All patients have potential to obstruct after extubation • Extra induction agent • Laryngoscope • ET tube

Flickr Delayed recovery

• Definitions for “delayed” recovery • Recovery last beyond an “acceptable” period of time. • Relative • Causes of delayed recoveries • Hypothermia • Pharmacological (reversal agents) • State of health • Benefits of delayed recoveries • Smoother • Increased IOP/ICP

Dogtime Reversal agents • Drug antagonist binds to receptor inhibiting the agonist • Opioid antagonists drugs • Naloxone • Butorphanol • Alpha 2 antagonist drugs • Yohimbine • Tolazoline • Atipamzole • Benzodiazepines • Flumazenil • Anticholinergic drugs • Atropine • Glycopyrrolate Questions and discussion…