RECOVER: BLS Flashcards
5 main vessels of the heart
Aorta Cranial vena cava Caudal vena cava Pulmonary artery Pulmonary vein
4 main valves of the heart
Pulmonic
Mitral
Aortic
Tricuspid
4 chambers of the heart
Right and left atrium
Right and left ventricle
Flow of blood (left side- oxygenated blood)
Lungs Pulmonary vein Left atrium Mitral valve Left ventricle Aortic valve Aorta Capillaries (out)
Flow of blood (deoxygenated- right side)
Capillaries Veins Vena cava e Right atrium Tricuspid valve Right ventricle Pulmonic valve Pulmonary artery Lungs
5 parts of conduction system
Sinoatrial (SA) node
Atrioventricular (AV) node
Bundle of His
Right and left bundle branches
Cardiac output: definition
The amount of blood delivered to tissues of the body each minute
Cardiac output: formula
CO= stroke volume(SV) x HR
Stroke volume
The amount of blood pumped during each contraction of the ventricle
3 determining factors of stroke volume
Preload
After load
Contractility
Preload
The amount of blood available to fill the left ventricle during diastole, that can then be pumped out to the body during systole
Afterload
The pressure against which the left ventricle has to push during systole
Determined by tone of peripheral blood vessels
Contractility
The strength with which the ventricle contracts during systole
Normal stroke volume in a dog
~1-2ml/kg
Normal cardiac output in a dog
100ml/kg/min
4 primary dysfunctions in cardiac arrest
Asystole
Pulseless electrical activity (PEA)
Ventricular fibrillation (VF)
Pulseless ventricular tachycardia (VT)
Physiology of asystole
Complete cessation of both electrical and mechanical activity
Physiology of PEA
No effective mechanical activity
ECG continues to show electrical activity
Physiology of VF
Aberrant, uncoordinated activity of muscle cells in ventricles
“Quivering” mechanical activity
No forward flow of blood out of the heart
ECG shows random irregular electrical activity
Physiology of pulseless VT
Rapid, ineffective ventricular contractions
Driven by abnormal myocardial cells rather than normal conduction system
Contractions too fast= no time for ventricular filling and no forward flow of blood
ECG shows regular, repeated electrical activity at rapid rate
2 main functions of the respiratory system
Ventilation- excreting CO2
Oxygenation- moving O2 in the blood
Alveoli
Small sacs with very thin membranes separating them from the pulmonary capillaries
Minute ventilation: definition
The amount of air that moves in and out of the respiratory system in one minute
Minute ventilation: formula
Tidal volume x respiratory rate
Reference range of arterial CO2
35-45 mmHg
CPR survival-to-discharge rate
Overall:
6-7%
Peri-anesthetic drug reactions or treatable underlying disease:
up to 50%
3 ways to assess breathing if no visible cheat excursions
Touch the chest
Auscultation
Cotton or microscope slide in front of nose (motion/fogging)
Why is agonal breathing considered a positive sign in CPA?
It suggests that the respiratory centers in the brain stem are still functioning and have not likely been deprived of perfusion for an excessive period of time
Why is pulse palpation not recommended prior to initiating CPR?
Insensitive and time consuming
Minimum MAP to palpate dorsal-pedal pulse
60 mmHg
Where to palpate apex beat
4th to 6th intercostal space on the lower 3rd of the chest
Pull elbow caudally to level of costochondral junction
Possible causes of pulselessness in animals with an auscultable heartbeat
Markedly decreased cardiac contractility
Severe shock
Pericardial effusion with tamponade
Severe pleural space disease
What percentage of normal cardiac output do proper chest compressions produce?
30%
2 theories on external chest compression technique
Thoracic pump theory
Cardiac pump theory
Cardiac pump theory
Based on the concept that the left and right ventricles are directly compressed during CPR
- between ribs in lateral
- between sternum and spine in dorsal
Determining factor of compression technique
Chest conformation
Thoracic pump theory
Based on the concept that external chest compressions raise overall intrathoracic pressure and push blood from the aorta into systemic circulation
Heart acts as a conduit rather than a pump
Thoracic pump technique
Compressions focused on the widest portion of the chest
Larger recoil= more effective refill
Cardiac pump technique
Compression force directly over the heart
Chest compression technique: patient positioning
Lateral recumbency
Dorsal recumbency in flat chested dogs
Chest compression technique: depth
1/3 to 1/2 the width of the chest
Chest compression technique: rate
100-120/min
Why are higher compression rates (>120) actually detrimental?
Decreased cardiac output due to decreased recoil time
How much time has to pass during compressions for aortic blood pressure to reach a level that provides perfusion?
1 minute
Which type of arrest is more common in animals?
Primary respiratory arrest
Cardiac arrest occurs secondary to hypoxemia from lack of ventilation
Why should intubation be done in lateral?
So that chest compressions don’t have to be stopped
Ventilation rate for intubated patient
10 breaths/min (every 6 seconds)
Why is a lower respiratory rate better in CPR?
Positive pressure ventilation increases intrathoracic pressure and compresses vena cavae
