Anesthetic emergencies in animals

Dr. Amit Sangwan PhD scholar

Dept. of Veterinary Surgery & Radiology

Anesthetic EmergenciesDoctoral Seminar-I of veterinary Surgery And Radiology

Tuesday 2 May 2023 1

Introduction Accidents may be sudden and

postoperative.

one kind of emergency may lead to another.

Final result tissue hypoxia.

Avoided by critical assessment and suitable monitoring.Tuesday 2 May 2023 2

High risk patients Neonates

Geriatric

Post trauma cases Low body wt. or morbid Cardiac , intracranial/intraocular surgery

Caesarian

Pulmonary pathologyTuesday 2 May 2023 3


Condition Protocol Remarks 1. Neonates Preanesthetic : atropine

Induction : propofol, Maintenance: isoflurane

Oxygen supplement

2. Ocular patients

Topical (proparacaine 0.5%)Preanesthetic : atropine ,acepromazine, diazepam, Induction: thiopentone or propofol Maintenance: isoflurane, sevoflurane , halothane

For Cardiac dysarrythmia : lignocaine

3. Trauma patients (a) Head injuries

Preanesthetic : diazepam Induction : propofol Maintenance: isoflruane ,

Manitol , frusemide, limited fluid therapy (1-2 ml/kg b. wt.)

Management of special cases


Condition Protocol Remarks

(b) Unstable haemodynamics

Preanesthetic :glycopyrrolate Induction : propofol, diazepam & ketamine Maintenanc: propofol, isoflurane

Fluid support

(c) Pulmonary Preanesthetic acepromazine Induction:propofol/ketamine/thiopentone with dazepam Maintenance: isoflurane

Rapid intubation and connected to oxygen source

4. Caesarian Preanesthetic: glycopyrolate Induction : ketamineMaintenance: propofol , isoflurane

Care of neonate (temperature , circulation and respiration)

5. Geriatric patients

Preanesthetic: atropine, diazepamInduction : ketamine+ diazepam, propofolMaintenance: propofol , isoflurane

Haemoglobin Desaturation Observing patient’s mucous membrane colour &

pulse oximeter. Etiology : (A) Anesthetic apparatus(i) Gas supplies(ii) Flow meters(iii) Emergency O2 bypass control(iv) Vaporizers(v) Breathing systems(vi) Scavenging(B) Ancillary equipments(vii)Endotracheal tubes (viii)Laryngoscopes (ix) Monitoring eqipements Tuesday 2 May 2023 6

Allergic Reactions Uncommon

Repeated exposure

Cross-reactivity

Hypotension Laryngeal edema Broncho constriction Cardiovascular collapseTuesday 2 May 2023 7

Prevention and cure Oxygen therapy

Intravenous fluids

Antihistamines

Corticosteroids



CARDIOVASCULAR EMERGENCIES

(A)Circulating fluid volume deficit

(B)Disturbances of cardiac rhythm Tachycardia Bradycardia Ventricular arrhythmia Heart block Cardiac arrest


(A) Circulating fluid volume deficit

Absolute reduction in volumes

Increase in vascular space

Haemorrhage

Restricted Cardiac Output

Body fluid loss during surgery

Autonomic reflex activities – vasodialation


Prevention and cure Fluid deficit corrected before anaesthesia is

induced

Crystalloid solutions

Colloids Blood transfusion Hb-based O2 carrying solutions

Gentle handling of tissues

(B) Disturbances of cardiac rhythm

Tachycardia (>180 bpm in dogs & >200 bpm in cats & > 75 bpm in horses and rminants)

Bradycardia (< 50-60 bpm in dogs & cats and

<25 bpm in horses and rminants)

Supraventricular arrhythmias

Ventricular arrhythmias

Heart blockTuesday 2 May 2023 12


Heart blockHeart block

Description ECG

1st degree

Delayed conduction of impulse from atria to ventricles

PR interval is lengthened

2nd degree Type 1

one or more of the atrial impulses fail to conduct to the ventricles

Progressive prolongation of the PR interval followed by a blocked P wave

Type 2 intermittently nonconducted P waves.

3rd degree

Complete block of impulse conduction

P waves with a regular P to P intervalRegular R to R interval represent the second rhythm.



Cardiac Arrest Pulse less electrical activity

Etiology :(a) Anesthetic overdose(b)Hypovolemia (c) Acute cardiogenic decompensation (d)Severe acidosis (e) Hypoxemia


Signs of cardiac arrest1. No palpable heart beat2. No palpable pulse3. Apnea4. Lack of surgical hemorrhage5. Cyanosis6. No muscle tone7. Dilated pupils (later)8. Increased CRT

CyanosisDilated pupil

CRT


TreatmentCardioplmonary Resuscitation

ABCD protocol for treatment of cardiac arrest:

1. Airways2.Breathing & Intermittent positive

pressure ventilation3. Cardiac massage 4. Drug


Cardiac Massage

External Thoracic

(A) Cardiac pump theory for <15-20

kg

(B) Thoracic pump theory for >15-20 kg

Internal Thoracic

more effective at perfusing

Interposed abdominal compression (IAC)involves manually compressing the abdomen in counterpoint to the rhythm of the chest compression.


External cardiac massage Internal cardiac massage


Placement of direct-current paddles for defibrillation of the heart during cardiac arrest.


Drug TherapyEpinephrine (0.05 to 0.1 mg/kg I/v), Vasopressin in asystolic cardiac arrest

(1.2 units/kg intra tracheal).Lidocaine (0.5 mg/kg I/v)Amiodarone (5 mg/kg I/v)Sodium bicarbonate (1 mEq/kg I/v)Atropine (0.02 to 0.04 mg/kg I/v)Glycopyrrolate (0.01 mg/kg I/v)


Respiratory Insufficiency1) Complications of laryngoscopy and

intubation2) Respiratory obstruction3) Laryngospasm and laryngeal edema4) Bronchial spasm5) Aspiration6) Hypoxemia7) Hypercapnia and hypocapnia8) Hypoventilation9) Aspiration pneumonia


1. Complications: laryngoscopy & intubation

1. Errors of ETT positioning

a. Esophageal intubationb. Endo bronchial intubationc. Position of the cuff in the larynx

2. Rough and inexperienced use of laryngoscopes.

3. Permanent scarring, ulceration and abscesses

4. Tooth damage


Signs

1. Inadequate tidal volume.

2. Retraction of the chest wall

3. Excessive abdominal movement.

4. Noisy breathing

5. Cyanosis

6. The natural heave of the chest and abdomen lost


The use of a wire-reinforced endotracheal tube will prevent kinking of the tube and obstruction of oxygen flow to patients. The protected endotracheal tube should be used when extreme flexion of the animal's head and neck or of the endotracheal tube is anticipated.

Kinked ET


2. Respiratory obstruction

Site for obstruction: By the tongue By soft palate Glottis laryngeal spasm, relaxed vocal cords and

Foreign Bodies Bronchospasm Oedema of the upper respiratory passage Large blood clots Faults of apparatus


(A) Brachycephalic dog soft palate may obstruct airway

(B) Soft palate in camel


(A) Acute flexion of a dog’s neck leading to kinking of endotracheal tube.

(B) Pressure inside cuff obliterate tube lumen


Prevention and cure Extending head on the neck and pulling

the tongue Endo tracheal tube Spraying of larynx with a local analgesic. Blood clots must be removed.

A B


3. Laryngospasm & Laryngeal edema

Sensory stimulation of superior laryngeal nerve.

pharyngeal secretions

Extubating in stage 2. Negative intrathoracic pressures

laryngeal crowing.


4. Bronchial spasm Ruminants : particularly liable. Initiated reflexly.

Signs: (a) Bout of coughing(b) Complete respiratory arrest. (c) Rigid chest and lungs(d) Stacking(e) Cyanosis mucous membranes.


Prevention and cure Initially 100%oxygen, Anterior mandibular displacement, Neuromuscular blocking agent Steroid (e.g. Dexamethasone @ 0.3

mg/kg I/v) Reintubation with a smaller tube. For bronchospasm: clear upper airway

and O2 enriched atmosphere. Adrenalin @ 2-5 ml in 1:10000 dilution.


5. Aspiration A result of vomiting or passive reflux Primary problem is respiratory

obstruction Bronchospasm Inhalation pneumonia Decreased esophageal sphincter pressure Pneumonitis Ulcerative esophagitis stricture formation


Prevention and cure Off fed prior to surgery or stomach

decompression Endo tracheal intubation with a cuffed

tube. Aspiration of the tracheobronchial tree. Oxygen should be administered. Relief of bronchiolar spasm. Tracheostomy .

35

Tracheostomy Tube

(C) for Horses(B) for small animals

(A) Aspiration of sub glottis secretions

Tuesday 2 May 2023


6. Hypoximea Etiology

Hypoventilation Respiratory obstruction Drug overdose

Clinical signs of hypoxia Jerky respiratory movement jaw and limb movements Sweating, tachycardia, cardiac

arrhythmias ,hypertension, and hypotension) later bradycardia, hypotension, cardiac arrhythmias


Prevention and cure Oxygen therapy. Expired air ventilation Chest deflation reflex Acupuncture Antagonists for anesthetic overdose. Eg.

Naloxone and naltrexone for opioid agonists.

Respiratory stimulants. Eg. Doxapram


(A) Oxygen therapy (B) Ambu self-inflating bag for IPPV

small-bore plastic tubing for O2

(C) Expired air ventilation (D) chest deflation reflex


Hypothermia Etiology

Depressed thermoregulation Excessive heat loss relative to metabolic

production Indiscriminant vasodilation. Larger body surface relative to body mass. Many anesthetic drugs

Effects Suppressed phagocytic activity Decreased migration of polymorphonuclear cells Reduced superoxide anion production, and Suppression of immune reactivity


Treatment1. Circulating warm-water pads,

2. Humidification and warming of inhaled gas

3. Ambient room temperature

4. Warm infusion fluids

5. Administration of oxygen


HyperthermiaEtiology

Drug-induced hyperthermia (rare) Accidental iatrogenic hyperthermia Malignant hyperthermia

Effects Intense skeletal muscle rigidity

(contracture), Rhabdomyolysis Hyperkalemia


Treatment Avoidance of known triggering agents.

Susceptible patients : Anesthesia: barbiturates, propofol and

tranquilizers Pre treatment: Dantrolene.


LOCAL ANALGESIAEtiology

Rapid injection : (a) hyperaemic or inflamed tissue(b) use of hyaluronidase Intravenous injection

Effects Both stimulate and depress CNS Cardiac conduction and contractility.


Treatment

IPPV withheld Analeptic drugs . Short or ultra- short acting barbiturates Intravenous fluid and vasopressive drugs. Chest compression or direct cardiac

massage

45

Epidural Analgesia and Regional NerveBlock

Etiology Inadequate aseptic technique Inadequate technique epidural injection

Effect Epidural abscessation Discospondylitis Prolonged CSF levels of drug, Myotonus Hind-limb ataxia and weakness. Local anesthetic toxicity Direct needle trauma to the nerve Hematoma formation.Tuesday 2 May 2023


Miscellaneous 1. Injuries

Corneal ulcers Tracheal mucosal injury Pulmonary barotrauma Obturator and facial nerve paralysis Falling fractures Post anesthetic myopathy

2. Anaesthetic Explosions And Fires Explosive inhalational agents Alcoholic skin disinfectants Use of oil and grease in oxygen cylinders

3. Intravascular Injection Barbiturate slough Venous thrombosis Haematoma formation


Conclusion Anesthesia risk is not much common.

Anaesthesia is still an art, and there is no substitute for experience, so an anesthetist should choose the protocol best known to him/her.

Cardiopulmonary complications are fatal and

attended with priority.

No single anesthetic agent provide all needed but a combination can be made better.


References Hall LW, Clarke KW and Trim CM (2000). Prevention and management of

anaesthetic accidents and crises. In Veterinary Anesthesia. 10th edition, W.B. Saunders, 507-532.

Tranquilli WJ, Thurmon JC and Grimm KA (2007). Lumb & Jones‘ Veterinary Anesthesia and Analgesia. Fourth Edition, Blackwell publishing.


Thank you

Health & Medicine

Anesthetic emergencies in animals