Anesthesia for Animals with Respiratory Disease PDF

Anesthesia for Animals with Respiratory Disease Michele (Mike) Barletta, DVM, MS, PhD, DACVAA Professor of Anesthesiology College of Veterinary Medicine University of Georgia  Learning Objectives Discuss the anesthetic risks and considerations for animals with respiratory distress Desc...

Anesthesia for Animals with Respiratory Disease Michele (Mike) Barletta, DVM, MS, PhD, DACVAA Professor of Anesthesiology College of Veterinary Medicine University of Georgia  Learning Objectives Discuss the anesthetic risks and considerations for animals with respiratory distress Describe the pre-anesthetic stabilization for animals with respiratory disease Develop a tailored anesthetic plan for animals with specific respiratory conditions Recognize and manage potential complications in animals with respiratory disease under anesthesia and in recovery  Outline Anesthetic management Upper airway disease Brachycephalic syndrome Laryngeal paralysis Rhinoscopy/rhinotomy Lower airway disease Intrapulmonary Extrapulmonary Anesthetic Management Minimize stress Pre-oxygenate Intubate rapidly Ventilate Monitor closely Into and during recovery Brachycephalic Syndrome (BOAS)  BOAS Components Primary Negative pressure during Elongated and thickened soft palate inspiration leads to: Stenotic nares Hypoplastic trachea Aberrant nasal turbinates Relative macroglossia/redundant pharyngeal tissue Secondary Everted laryngeal saccules (grade I laryngeal collapse) Laryngeal collapse (progressive – grade II and III) Bronchial collapse Everted tonsils Pharyngeal/laryngeal edema https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0181928 Esophagitis/regurgitation/aspiration Cor pulmonale Elongated Soft Palate and Everted Saccules  Preparation and Induction Minimize stress Trazodone and gabapentin PO before drop off Butorphanol +/- acepromazine IV PRN Cool them down if hot After pre-meds watch them closely Pre-oxygenate Have suction ready Wide selection of cuffed ETTs available  Preparation and Induction Corticosteroids IV prior to surgery to minimize laryngeal swelling (no NSAIDs) Oxygen insufflation during laryngeal exam Intubate rapidly Propofol, alfaxalone Monitor closely Use GI drugs Prokinetics → metoclopramide Gastroprotectants → famotidine or omeprazole Antiemetics → maropitant or ondansetron Caudal Maxillary Block  Recovery ETT in place until dog is alert, may need to reverse drugs if possible Monitor closely for hours to ensure airway obstruction does not occur Signs of obstruction- exaggerated airway movements without obvious air movement, cyanosis, mental distress, too quiet Be prepared to re-anesthetize and re-intubate or do tracheostomy Keep and ETT on the cage door Might need to perform a tracheostomy  Laryngeal Paralysis In older large breed dogs → tie-back surgery Can cause partial or complete airway obstruction Tranquilizer (acepromazine) + oxygen will minimize stress Monitor very closely General anesthesia might need to be induced urgently IV anesthesia to do laryngeal exam Propofol or alfaxalone better for laryngeal exam May need doxapram to assess laryngeal function Anti-inflammatory corticosteroids (make sure no NSAIDs on board) For Laryngeal Exam  Management Avoid full µ agonist Increased risk of regurgitation and aspiration Sedation Acepromazine + dexmedetomidine (low doses) +/- butorphanol Induction Propofol or alfaxalone better for laryngeal exam May need doxapram to assess laryngeal function Analgesia Lidocaine CRI, ketamine CRI, butorphanol if needed Anti-inflammatory corticosteroids (make sure no NSAIDs on board) Regurgitation intra-op and at extubation Use metoclopramide and maropitant  Rhinoscopy and Rhinotomy Obstruction can be unilateral or bilateral Open mouth breathing? Cats can present with severe symptoms Main anesthetic concerns Pain → use full µ agonist opioids, ketamine, dexmedetomidine (when indicated), and local blocks! Blood loss → monitor and use blood product if necessary Aspiration → ETT with cuff (good seal) + pharyngeal gauze packs (remove before extubation) Post-procedural obstruction → monitor and intervene promptly CAUDAL MAXILLARY BLOCK Maxillary Tuberosity or Intraoral Approach CAUDAL MAXILLARY BLOCK Subzygomatic or Transcutaneous Approach CAUDAL MAXILLARY BLOCK Infraorbital Approach  Outline Anesthetic management Upper airway disease Brachycephalic syndrome Laryngeal paralysis Rhinoscopy/rhinotomy Lower airway disease Intrapulmonary Extrapulmonary  Intrapulmonary Disease Infectious diseases Bacterial, viral, fungal pneumonia Inflammatory diseases Chronic bronchitis, canine eosinophilic bronchopneumopathy, feline asthma Neoplastic diseases Primary pulmonary tumors and metastatic disease Miscellaneous diseases Traumatic (lung contusion) Pulmonary Thromboembolism Cardiogenic and non-cardiogenic pulmonary edema  Intrapulmonary Disease May need general anesthesia For diagnostic procedures (i.e. bronchoscopy and bronchoalveolar lavage) Unrelated to intrapulmonary disease Minimize stress Provide O2 flow-by before induction Best to secure the airway quickly Propofol or alfaxalone for induction Maintenance Inhalants Injectable (i.e. propofol or alfaxalone CRI) For bronchoscopy in small dogs and cats For bronchoalveolar lavage Courtesy of Dr Dantino Extraparenchymal Pulmonary Disease Pleural space Pleural effusion Pneumothorax Chest wall Traumatic (flail chest, rib fracture) Neoplasia Diaphragmatic hernia Obesity and abdominal (organ) distension Neurologic disfunction  Pneumothorax and Pleural Effusion Thoracocentesis to remove air or fluid prior to anesthesia How? Sedation to minimize stress Butorphanol IM +/- low dose of dexmedetomidine if necessary Place IV catheter for administration of more drugs and for emergency Can be preformed under general anesthesia but before the surgical/diagnostic procedure Chest tubes if there is significant amount of air or fluid Pneumothorax  Recovery Continuous oxygen therapy Flow by/oxygen cage Nasal cannula High flow nasal cannula Monitoring Reflectance SpO2 probes For respiratory distress Pain management Opioids and ketamine Sedation when indicated to reduce stress Acepromazine, dexmedetomidine, gabapentin High Flow Nasal Cannula (HFNC)  Diaphragmatic Hernia Pre-Anesthetic Considerations Provide oxygen therapy Minimize stress Place the patient in an upright or sternal position to improve ventilation Perform thoracocentesis if indicated Sedation Opioids Benzodiazepines +/- low dose alfaxalone +/- low dose dexmedetomidine if cardiovascularly stable  Anesthesia Monitoring before induction if possible Plan ahead for complications Have emergency drugs calculated and ready Induction Rapid-sequence induction: secure the airway quickly Use controlled ventilation To maximize lung expansion and gas exchange Necessary for thoracotomies Maintenance Inhalants Can tilt the table (head up) to release some of the compression caused by the herniated organs  Management Avoid sudden re-expansion of compressed lung tissue Can cause re-expansion pulmonary edema Gradual reinflation and careful monitoring of lung compliance If the hernia is chronic Higher risk of morbidity/mortality due to reperfusion injury and chronically atelectatic lungs Use lidocaine CRI Administer corticosteroids Pain management Systemic → opioids, ketamine, lidocaine Local blocks → intercostal block, transversus thoracis plane block  Recovery Continuous oxygen therapy Flow by/oxygen cage Nasal cannula High flow nasal cannula Monitoring Reflectance SpO2 probes For respiratory distress Pain management Opioids and ketamine Sedation when indicated to reduce stress Acepromazine, dexmedetomidine, gabapentin Severe Dyspnea in O2 Cage Reflectance SpO2 Probes