Page 168 - Cote clinical veterinary advisor dogs and cats 4th

Anesthetic-Related Complications 65

PHYSICAL EXAM FINDINGS Initial Database consider lidocaine 2 mg/kg IV, followed
See History, Chief Complaint section. • Heart rate and rhythm; pulse palpation by continuous IV infusion of 30-50 mcg/
VetBooks.ir Etiology and Pathophysiology • Mucous membrane color, capillary refill time • If tachycardia is due to hypovolemia (p. 911), Diseases and Disorders
kg/min.
• Blood pressure
consider IV bolus of isotonic crystalloid fluids
(CRT), packed cell volume (PCV), and total
Respiratory complications:
• Anesthetic agents cause respiratory depression
solids (TS)
and sometimes apnea. Patient positioning can • Anesthetic depth (5-10 mL/kg or more, as indicated by serial
reassessment).
lead to atelectasis of dependent lung lobes. • Body temperature Hypotension:
Tight restraint may cause hypoventilation. • Respiratory rate and effort, auscult for normal • Lighten anesthetic plane if too deep.
• Equipment malfunction can lead to rebreath- lung sounds bilaterally; evaluate capnogram • If also bradycardic, administer atropine
ing of CO 2 , delivery of a hypoxic gas mixture, and end-tidal CO 2 (ETCO 2) (0.01-0.04 mg/kg IV) or glycopyrrolate
or failure of anesthetic gas delivery. • Hemoglobin saturation by pulse oximetry; (0.01 mg/kg IV).
• Tracheal tears lead to pneumothorax, consider arterial blood gas to assess hypoxemia • If the patient is hypovolemic, administer a
pneumomediastinum, and/or subcutaneous • Evaluate anesthetic equipment, ensure proper bolus of isotonic crystalloid replacement
emphysema. functionality solution (5-10 mL/kg IV) unless the patient
• Closure of the pop-off valve or administration is unable to tolerate a fluid bolus (e.g., due
of positive-pressure ventilation with excessive TREATMENT to cardiac disease).
airway pressure can result in barotrauma and • Consider partial intravenous anesthesia with
pneumothorax. Treatment Overview opioids and tranquilizers to reduce inhalant
Cardiovascular complications: Support oxygen delivery to tissues through requirement.
• Many anesthetic agents cause cardiovascular cardiovascular and respiratory stability. Identify • For refractory hypotension, consider the use
effects, including bradycardia, arrhythmias, and eliminate cause of complication. Physiologic of positive inotropes and vasopressors.
vasodilation, and hypotension. abnormalities should be managed as soon as Hypothermia warming strategies (p. 523):
• Surgical manipulation of the heart and possible. • Blankets to prevent radiant heat loss
thoracic structures can cause arrhythmias. • Avoid contact with cold surfaces.
• Hemorrhage secondary to surgery decreases Acute General Treatment • Increase room temperature.
cardiac output. Apnea/hypoventilation, cyanosis, pallor: • Avoid cold lavage/scrub solutions.
• Patients with pre-existing cardiovascular • Manual positive-pressure ventilation should • Forced air warming devices
disease may be more susceptible. be provided in the presence of apnea or • Circulating warm water blankets
Neurologic complications: hypoventilation; subjectively assess compli- • Heating pads designed for use with veterinary
• Patients with pre-existing intracranial disease ance of the patient’s lungs while providing patients
are susceptible to the consequences of manual breaths. A sudden increased resistance • Radiant heat support by ceramic or infrared
increased intracranial pressure associated with to delivering a breath could indicate pneu- warmers
hypercapnia, hypoxemia, and/or hypertension. mothorax or airway obstruction. Neurologic complications:
• Blindness has occurred in cats after use of a • Administer 100% oxygen. • For continued sedation/obtundation, reverse
mouth gag due to maxillary artery occlusion. • Assess patient’s cardiovascular status; rule out anesthetic agents.
Musculoskeletal complications: cardiac arrest. • Provide supportive care, including manual
• Propofol and alfaxalone occasionally cause • Lighten anesthetic plane if too deep. ventilation until patient can appropriately
myoclonus. • If an anesthesia machine malfunction is ventilate, oxygen supplementation, heat
Thermoregulation: suspected, disconnect patient from the support, fluid therapy, etc.
• Anesthetic agents depress the thermoregulatory anesthetic circuit and administer breaths • Measure blood pressure, PCV/total protein
system. Hypothermia can cause alterations in using an Ambu bag. (TP), blood glucose and correct as necessary
coagulation, increased wound infection rates, • Ensure that the endotracheal tube is placed
reduced metabolic rate, decreased anesthetic correctly and at the correct depth. Possible Complications
requirements, arrhythmias, and death. • Consider reversal of drugs that can contribute • Hypotension or hypoxemia can damage vital
• Hyperthermia can occur in cats receiving to hypoventilation. organs.
mu-agonist opioids. Tachypnea: • Hypothermia can lead to anesthetic overdose,
• Hyperthermia and burns may result from • Adjust anesthetic plane if indicated. increased infection rates, arrhythmias, cardiac
overzealous heat support (p. 138). • Perform thoracocentesis (p. 1164) if pneu- arrest.
• Malignant hyperthermia is a rare complica- mothorax is suspected. • Hypercapnia, hypoxemia, or severe hyperten-
tion of inhalants. • Ensure normothermia. sion can lead to increased intracranial
Bradycardia: pressure, especially in patients with pre-
DIAGNOSIS • Assess airway equipment and anesthesia existing intracranial disease.
machine, ensuring proper function (e.g., • Prolonged recovery from anesthesia is a
Diagnostic Overview pop-off valve open). common sequela of anesthetic overdose,
A physical exam should be performed to identify • Identify possible causes of vagal stimulation. decreased metabolic rate, hypothermia,
the body systems affected and direct diagnostics. • If hypotension is identified, heart rate is unac- hypoglycemia, and hypotension.
ceptably low, or heart rate is rapidly falling,
Differential Diagnosis administer atropine (0.02-0.04 mg/kg IV) or Recommended Monitoring
• Surgically-induced respiratory/cardiovascular glycopyrrolate (0.01-0.02 mg/kg IV). • Heart rate and rhythm by electrocardiogram
complications (e.g., pneumothorax, hemor- • Consider reversal of drugs associated with (ECG); pulse rate and quality
rhage, vagal reflexes) bradycardia (alpha-2 agonists, opioids). • Blood pressure, CRT
• Progression of primary disease (e.g., sepsis, • Ensure normothermia. • Pulse oximetry, mucous membrane color
hemorrhage, traumatic brain injury) Tachycardia: • Capnography; respiratory rate and effort
• Neurologic dysfunction due to surgical • Ensure adequate depth of anesthesia. • Body temperature
manipulation • Ensure adequate analgesia. • Arterial blood gas
• Failure or misinterpretation of monitors • For ventricular tachycardia (heart rate • Serial PCV/TP and blood glucose concentra-
• Anesthesia machine malfunction > 180 bpm with ventricular complexes), tions

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