ECG interpretation

Question 1

what is hypoxemia

Answer 1

Hypoxemia a PaO2 less than 60 mmHg
Normal values in horses breathing room air are 90 –100 mmHg.

Question 2

name 4 causes of hypoxemia

Answer 2

1. Hypoventilation
2. reduced FIO2 (inspired oxygen fraction)
3. V/Q mismatching.
4. Anatomical shunting.
5. Diffusion impairment.
6. Hypoxia tissue perfusion
7. decreased perfusion
8. hypoxemia due to a decrease in Hb saturation
9. anemia
10. O2 transport issue (edema..)
11. O2 utilization by the cell
    1.

Question 3

Increased PaCO2 is defined as respiratory acidosis. Name 2 causes:

Answer 3

Hypoventilation.
hyper metabolic state

Question 4

Horse is in apneia what do you give?

Answer 4

Apnea Doxapram 0.5 to 1 mg/kg

Question 5

Increase EtCO2 , name 4 causes

Answer 5

1. hypoventilation
2. Soda lime is ineffective leading to rebreathing of CO2
3. Increased production of CO2 (light plane a hyperthermia
4. Decreased ETCO2
5. Circuit disconnection.
6. Obstruction of endotracheal tube.
7. Significant decrease in cardiac output (check blood pressure).
8. Cardiac dysrhythmias (causing a reduced cardiac output).
9. Cardiac arrest (delivery of CO2 to the lungs requires blood flow).
10. Pulmonary embolism.

Question 6

No EtCO2, name 4 causes

Answer 6

Esophageal intubation.
Apnea (squeeze rebreathing bag and ETCO2 will register if in tracheaa
Endotracheal tube blocked or kinked.
Obstruction of equipment or airway.

Question 7

Blood pressure:
target mean arterial blood pressure for adults and foals

Answer 7

70 and 90 mm Hg adults
50 and 65 mm Hg
is recommended
In foals

Question 8

Hypotension what to you give (<70 mmHg)? dose, type of drug

Answer 8

Dobutamine (0.5–2 μg/kg/min IV as constant-rate infusion [CRI]), an inotropic drug that mainly acts on β-1 receptors, is ideal for treatment of hypotension

Question 9

Urine normal values for adult and foal

Answer 9

normal values of approximately 0.5 mL/kg/hour even in water-deprived animals
Foals with kt is 6 mL/kg/hr

Question 10

what is hypoventilation?
what is hypoxemia?

Answer 10

defined is partial pressure of carbon dioxide >45 mm Hg, and
hypoxemia, defined as partial pressure of oxygen <80 mm Hg

Question 11

Hypoventilation/hypoxemiaa , what should you do?

Answer 11

1. ↑ tidal volume, RR, recruitment maneuver,
2. albuterol,
3. increase inspiratory:expiratory ratio,
4. increase arterial blood pressure by increasing IV fluids.

Question 12

4 causes of hypotension?

Answer 12

myocardial depression (anesthetic agent, endotoxemia…)
decrease vascular resistance
hypovolemia
bradycardia

Question 13

hypertension causes?

Answer 13

inadequate plane of anesthesia
drug induced (alpha2 or dobutamine, atropine…)
hypercapnia, hyperthermia
tourniquet

Question 14

Answer 14

Atrial fibrillation (AF) is characterized by the absence of P waves, the presence of fibrillation waves or
f waves and irregularly irregular RR intervals with a normal QRS morphology

**Treatment: **pharmacological cardioversion using Quinidine oral
Or Electrical cardioversion

Question 15

Answer 15

Second degree AV block
Intermittent failure of the atrial impulse to conduct toward the ventricles is called 2nd degree AV block. This
is the commonest physiological dysrhythmia found in horses. Every QRS complex is preceded by a P wave, but not every P wave is followed by a QRS complex

WHY? is usually caused by a high vagal tone  exercise or atropine should solve

Changes in BP are characterized by an initial hypertension followed by hypotension. The use of atropine to treat AV blocks is normally not necessary.

Question 16

What treatment should be given in first and second degree atrioventricular block and bradycardia?

Loomes,K.,2021.TheuseofhyoscineN‐butylbromidetotreatintraoperativebradycardiaduringisofluraneanaesthesiainthreehorses.EquineVeterinaryEducation,33(5),pp.e113-e119.

Answer 16

b) 0.02-0.04mg/kg IV atropine, 5ug/kg IV glycopyrrolate or 0.1-0.2mg /kg IV hyoscineN-butylbromide.

Question 17

Answer 17

third-degree AV block

Question 18

causes of 3dr degree block?

Answer 18

Uroabdomen: The most common life-threatening arrhythmia observed in foals with uremia and hyperkalemia is a third-degree AV block, which may be precipitated by surgical stimulation.

Discontinuation of surgical stimulation and administration of atropine at higher than usual doses (i.e., 20–40 μg/kg IV ou 0,2-0,4 mg/kg) and/or ephedrine (25–50 μg/kg IV) may resolve the arrhythmia.
If not effective, epinephrine (10–20 μg/kg IV) and closed chest massage must be initiated (AUER p 329)

Question 19

what happens to ECG in hyperkalemia situations?

Answer 19

K+ concentrations reach values in excess of 5.5 mEq/L, progressive changes in the ECG such as flattening of P-waves

Question 20

how do you correct hyperkalemia?

Answer 20

Serum K+ can be effectively decreased to clinically acceptable levels by administering regular insulin at a dose of 0.1 to 0.3 IU/kg slowly IV in 2.5% to 5.0% dextrose over 30 to 45 minutes prior to induction of anesthesia. Hyperkalemia associated with hyperkalemic periodic paralysis, urinary tract obstruction, or bladder rupture are examples that warrant immediate treatment with intravenous calcium and sodium bicarbonate, with additional use of glucose and insulin or furosemide if the problem cannot be resolved quickly.

Question 21

uroperitoneum may lead to life threatning metabolic acidosis (pH<7.2)

Answer 21

in the situations of a life-threatening metabolic acidosis (pH <7.2) administration of sodium bicarbonate (Na+HCO3−) may become necessary.

The required dose of Na+HCO3− (in mEq) to be administered can be determined based on the **base deficit (-BE): -BE [in mEq/L] × 0.6 × body weight in kg. ** (FOALS and adults 0.3

One half of the calculated bicarbonate dose should be administered first over 20 to 30 minutes and then a blood gas analysis repeated to assess the effect before the second half of the dose is administered.

Question 22

Answer 22

Question 23

what do you administer in ventricular tachycardi?

Answer 23

(Lidocaine 2% Injection 1mg/kg bwt i.v.) was administered over 5min; however, this did not immediately improve the arrhythmia which subsequently spontaneously resolved over the following 24h

Question 24

cardiac arrest what do you givE?

Answer 24

0.01 to 0.02 mg/kg of epinephrine intravenously every 3 minutes
epinephrine may be given by the endotracheal route at a dose of 0.05 to 0.1 mg/kg diluted in 1 to 2 mL of saline.
Complications of epinephrine administration include ventricular fibrillation (V-fib) (AUER page 328)

Question 25

Answer 25