Canine/Feline Anesthesia And Anesthetic Monitoring/Problems Flashcards
Describe anesthetic techniques commonly used in small animal practices.
I. Multimodal general anesthesia (premedicate, IV induction, Inhalant maintenance)
II. Sedation/Neurolept analgesia – procedures, aggressive patients
III. Local/regional anesthesia – part of multimodal aneshtesia
List strategies used to minimize adverse effects when selecting an anesthetic protocol.
I. Minimum patient database
II. ASA status (PS1 – healthy; tailor proctol based on individual patient)
III. Procedure – correct dehydration, hypotension, anemia
IV. DVM drug preference (multimodal, double check dose, label syringes, administer ‘to effect’ – smallest dose possible generating desired effect)
Describe how different methods of anesthetic induction and maintenance influence the dynamics of an anesthetic event.
- IM induction – peak effect by 30 min, metabolized 60min; little control depth & peak
- IV (profol) – peak 5 min, metabolized 10-20min
Control peak effect (repeat bolus), not duration - Total intravenous anesthesia TIVA (intermittent bolus) – rapid induction & maintainable; depth increase as more bolus given
- Inhalant – peak 5 to 8 min, better control depth but can be delayed (RD, agent, flow rate)
- IV & inhalant – induction <5min, control depth, rapid recovery
Describe the process of induction
- Gather equipment – machine, ETT, mask, monitoring devices, warming device, drugs, crash cart
- Premedicate – ease stress, IV catheter placement, reduce induction agent & prevent windup
- Conscious – excitement (prevent with preanesthetic) – general – surgical anesthesia
Describe induction of general anesthesia by IV injection of an ultrashort-acting agent, by mask or chamber induction, or by IM injection.
Explain cautions and risks associated with each method of anesthetic induction and strategies to maximize patient safety.
IV induction (Ketamine&Midazolam, Propofol): Give initial bolus (1/2); check HR, RR, jaw tone, pedal, palpebral reflex; titrate (give more bolus until effect)
Inhalation: Iso (3-5%), Sevo (4-6%) by mask/chamber
- Patient may struggle, vitals hard to obtain
- Exposure to WAG, no airway control
- Vomit/regurgitate, epinephrine release
IM (neuroleptanalgesia): aggressive, give entire dose, slow onset, longer recovery
List reasons for, advantages of, and potential complications of endotracheal intubation.
Advantages: open airway, deliver fresh gas efficiently (low WAG, flow rate), reduce aspiration & dead space (more gas in alveoli), ventilation, CPR
Disadvantage: irritation, trauma, stimulate vagus nerve (bradycardia, hypotension), overzealous (damage trachea), overinflate, obstruction, chew tube
Steps of Endotracheal Intubation
- Supplies – ETT (3-4.5mm cats, 7.5-8 10kg dog), syringe, gauze, lidocaine, IV tubing, larygoscope
- Induce into light stage III – sternal recumbency
- Assistant grasp maxilla, raise head, extend the neck
- Grasp tongue with sponge, visualize larynx
- Displace epiglottis ventrally, insert ETT in rotating motion – do not force, exchange tube
- Place patient laterally, check tube is trachea, secure
- Turn on flowmeter, connect ET to breathing circuit, inflate cuff, turn on vaporizr & monitor
Explain the process of intubation
How to check tube in trachea – moving RB, air moving/fogging in tubing, valves, palpate ETT, capgnograph
Tie gauze using surgeon knot, loose end over head/behind head (brachycephalic, cats)
Inflate cuff until pressure at 20cm H2O (close pop off valve, compress bag watching pressure manometer)
Cats (laryngospasm) – inject 0.1mL Lidocaine in glottis
Describe maintenance of general anesthesia by administration of an inhalant agent, injection of repeat IV boluses of an ultrashort-acting agent, or constant rate infusion (CRI).
Inhalant: Iso (1.5-2.5%), Sevo (2.5-4%), change increments 0.5-1% or add opioid/injectable
TIVA: 0.10 to 0.25 induction volume q 3-5min
CRI: Propofol & Alfaxalone, adjust rate
IM – not to be used with propofol (short duration procedure)
List principles of providing for patient positioning, comfort, and safety during anesthetic maintenance.
Position: lateral recumbency
Needle is not left in Tport, double check IV access
ETT maintenance – disconnect first when repositioning, do not drag, watch RB
Heat support, eye lubrication q 1-3hr
List factors that affect patient recovery from anesthesia, the signs of recovery, appropriate monitoring during recovery, and oxygen therapy during recovery.
Recovery = time when anesthesia discontinued, able to walk/stand. Based on procedure time, condition, anesthesia used, temperature, breed
Signs ↑ HR, RR, RV; central eyeball; return of reflex, shivering, voluntarily head movement, delirium
Monitor: hypoxemia, cardiac arrhythmia, delayed conciousness, hypothermia/abnormal vitals
Administer reversal/analgesia, O2 (50-100mL/kg/min), extubate, general nursing care
Describe the process of extubation.
Extubate – once swallowing reflex, chewing, head movement
- Deflate cuff until balloon empty, untie tube
- Remove ETT when patient can lift head (brachycephalic), do not delay on cats
Dentals – keep cuff partially inflated, remove fluids, keep patient lateral/sternal, extend head
Describe general nursing care during the postanesthetic period.
Remove any ties, probe, cuff, ECC electrode
Keep IV catheter – fluid maintenance
Gently stimulate – turn, rub chest, turn q 10-15 (hypostatic congestion)
Gradual warming (Bair hugger), padded bedding
NPO 1-2 hours, gradual introduction of water (except neonates)
Explain the principles of anesthetic monitoring, including the reasons for and goals of monitoring.
Monitor vital signs – proper circulation, oxygenation, ventilation (patient safe)
Monitor anesthetic depth – adequate CNS depth, analgesia, muscle relaxation/immobility
List and describe each of the stages and planes of anesthesia.
Stage 1 (voluntarily movement)
Induction agent given → Stage I (signs pronounced mask/chamber induction, less premedicated)
Dysphoria/disoriented
Normal vitals ↓ awareness of pain
Recumbent
Patient begin to loose conciousness
List and describe each of the stages and planes of anesthesia.
Stage 2 (involuntary movement)
Stage II → loss of spontaneous muscle movement
(Signs pronounced mask/chamber induction, less premedicated)
Involuntarily movement, vocalization
Struggle, ‘paddle’ (causes epinephrine release)
Normal reflex
Dysphoria
↑ HR, RR, dilated pupils, marked muscle tone, apnea/irregular respiration
List and describe each of the stages and planes of anesthesia.
Stage 3 (light)
Best time to intubate, minor procedures
Muscle relaxation, patient calm/non-vocal
↓ HR, ↓↑ RR, normal respiratory pattern
Eyeball center, pupil constricted, ↓ PLR
Pedal & palpebral present; reduce gagging, laryngeal, swallowing
List and describe each of the stages and planes of anesthesia.
Stage 3 (surgical)
Completely unconciousness & immobile
Slight ↓ HR, RR, BP in absence of pain, HR/RR mildly ↑ for painful stimuli
Moderate pupil size, ventromedial eye rotation
Reflexes sluggish - PLR, lacrimation; absent - pedal, swallowing; lost - laryngeal & palpebral
List and describe each of the stages and planes of anesthesia.
Stage 3 (deep)
Depth too deep progressing into cardiac/respiratory depression
↓ HR, RR, VT , BP unchanged to surgical stimulation
↓ pulse strength, pale MM, prolonged CRT
Loss of all reflex
Abdominal breathing/contraction
Central eyeball, widely dilate, unresponsive pupil
Flaccid jaw tone (very relaxed muscle tone)
List the monitoring parameters used primarily to determine whether or not the patient is safe and group them according to whether they primarily assess circulation, oxygenation, or ventilation.
Circulation/Perfusion
- Parameter: HR/rhythm, pulse, CRT, MM, BP
Oxygenation
- Parameter: MM, SPO2, Blood gas
Ventilation
- Parameter: RR/RD, Breath sounds, ETCO2, PACO2, Blood pH
ACVAA Guideline - Circulation
- Always: palpate peripheral pulse, awareness of heart rate, rhythm, quality
- Always: evaluate CRT & MM color
- Intermittent: Auscultate heartbeat stetoscope
- Continuous: Esophageal statoscope (audible monitor)
- Periodic: SPO2
- Periodic: ECG to detect arrhythmias
- Periodic: Blood pressure
Vital Sign
Heart Rate (HR)
HR ↓ bradycardia: dex, opioids; excessive anesthetic depth/adverse reaction
HR ↑ tachycardia atropine, acepromazine; inadequate depth, pain, blood loss/shock, hypoxemia, hypercapnia
Palpate apical pulse (femoral artery), ausculate heart
Explain setup, operation, care, maintenance, and troubleshooting.
Esophageal Stethoscope
Catheter instered into esophagus (5th rib) connected to audio monitor amplifying heart sound (adjust volume)
Clean catheter with chlorhex, change batteries
Explain setup, operation, care, maintenance, and troubleshooting.
Heart Rhythm/ECG
Abnormal rhythm is only visualized through ECG – attach color coded electrod to pt, recorded into leads/views (Lead I/II GA); artificats – moving, exagerrate breathing
Pt is placed on towel (nonconductive), record 1-2 min
Normal baseline, P wave (atria contract - ventricle), PR interval (SA node – purkinje fiber), QRS complex (ventricle contract – pulmonary artery & aorta), ST segment (flat), T wave (repolarization/filling ventricles)
Be familiar with certain rhythms on an electrocardiographic tracing (I)
- NSR: normal HR, equal distance between QRS complex
- SA: ↓ HR expiration (short QRS), ↑ HR inspiration (long QRS), normal in healthy dog
- Sinus bradycardia: slow HR (excessive depth)
- Sinus tachycardia: fast HR (inadequate depth)
- AV hear block: delay in conduction of AV ndoe (Dex, high vagal tone, hyperkalemia)
• 1st degree: prolong PR interval
• 2nd degree: occasional missing QRS, prolong PR
• 3rd: No P/QRS relationship (↓ cardiac output, tx)
Be familiar with certain rhythms on an electrocardiographic tracing (II)
- Supraventricular complex (SPC): QRS close, +/- P wave
- Supraventricular tachycardia: >3 SPC
- Ventricular Premature Complex (VPC): ≥1 wide & bizarre QRS closely follow previous (common in anesthesia, treatment based on frequency)
- Ventricular tachycardia: >3 VPC (tx with Lidocaine)
- Atrial fibrillation (chaotic contraction): absent P waves, normal QRS irregular interval
- Ventricular fibrillation: unrecognizable QRS complex (CPA) → PEA (no pulse/heart contraction)
Vital Sign:
Capillary Refill Time (CRT)
Rate of return of color to (oral) mucous membranes after applying gentle digital pressure; >2 sec = reduced tissue perfusion & temperature
Epinephrine release, hypotension, hypothermia, excess depth, shock
Vital Sign:
Blood Pressure (BP)
Force exerted of flowing blood on arterial walls = indicator of perfusion for anesthetized patients (interaction of HR, stroke volume = amount ejected, vascular diameter, arterial elasticity, blood volume
PSYS: contraction of L ventricle – aorta/arteries
PDIA: pressure remaining in arteries (RA & LA filling blood
MAP: average pressure throughout cardiac cycle (diastole, atrial systole, ventricular systole); best indicator of tissue perfusion
Hypotension: dehydration, shock, sepsis, GDV, tachycardia
Hypertension: pain, light plane, disease, drugs
