Pulse Palpation, HR/Rhythm, ECGs Flashcards
Pulse Pressure
= SAP – DAP
Advantages of Pulse Palpation
Proof of circulation, life
Technically easy to perform
Disadvantages of Pulse Palpation
No numbers
No information about MAP
No indication of adequacy of tissue perfusion
Impaired by hypovolemia, VC
Dagnall, Wilson, and Khenissi 2022 (VAA)
54 client owned dogs, palpation of femoral pulses had greatest likelihood of success with least amount of time versus radial, dorsal pedal and conscious and anesthetized dogs
o Monitoring femoral pulse during induction: confirmation of spontaneous circulation
o Pulse palpation improves with clinical experience
Consequences of Abnormal Rhythms
o Altered, impaired CO
o Hypotension
o Increased MVO2, reduced coronary perfusion (tachyarrhythmias)
o Increased risk defibrillation +/- death
High Heart Rate
tachycardia – shortened diastolic filling time, reduced SV
DDx
Light level of ax: nociceptive response during sx, arousal
Drugs: ketamine, anticholinergics, sympathomimetics
Metabolic: hypovolemia, hypoxemia, hypercapnia, hyperthermia, pain
Dz: pheo, hyperthyroidism
Hz dz: SVT, VT
General Tx Parameters for Tachycardia
20% above normal – poor CO, BP, tissue perfusion
Large dogs >150, small dogs >190; cats >260
Horses >55, SR >110
Treatment Triggers for Ventricular (Tachy) arrhythmias
Evidence of impaired forward flow (CO, BP, tissue perfusion)
Concern for progression to vfib – 3 triggers
3 Triggers for Concern about Progression to Vifb
- Rate >180-200bpm
- Progressive arrhythmia: increasing number, multiformity
- R-on-T: ectopic complex overlies preceding complex
If observable isoelectric period btw two complexes, no R on T
If last waveform runs into next waveform without isoelectric period (even once), R on T
Low HR
bradycardia – diminishes CO
o DDx
Ax agents: a2s, opioids, ax agent overdose
Increased vagal tone: parasympathomimetics, ETT, abdominal nociception/traction, OCR, high BP, breed/species
Metabolic: hypothermia, end-stage hypoxemia/severe myocardial hypoxemia, hyperkalemia
Heart dz: SSS, AV conduction system
Bradycardia Tx Guidelines
o Tx: 20-30% below baseline; CS of poor CO, BP, tissue perfusion
<50 large dogs, <60 small dogs, <90 cats
<25 horses, <55 SR
ECG
- Voltmeter measuring electrical potential differences across heart – sum of vectors of depolarization APs, repolarization
o Graphical representation of electrical activity of heart, represented by positive (neg to positive electrode), negative (pos to neg) deflections or flat lines (perpendicular to lead electrodes)
Evaluation of ECG
o P for every QRS?
o QRS for every P?
o Regular rhythm?
o Appropriate rate?
Lead I
3p
RA, LA
aVL
2p
Lead II
5p (60*)
aVF
6p (90*)
Lead III
7p (120*)
aVR
10p
Troubleshooting ECG
o Palpate pulse – ensure not PEA
o Correct lead placement
o Contact: dry, inadequate coupling gel
o Patient motion
o Exogenous electrical activity: MRI, cautery, external pacing
Standard ECG Paper Speed
o Standard: 25mm/second – 1 small square (1mm) = 0.04s, 5 small squares = 1 large square, 0.2s, 5 large squares = 1 second
300 large squares = 1 min
Three methods for ECG Calculation based on paper speed
- Large Square Method
- Small Square Method
- R to R interval method
Large Square Method
Divide 300 by # of large squares btw each R-R intervals
Small Square Method
1500 divided by number of small squares btw consecutive R waves
R Wave Method
Rate = # of R waves (rhythm strip) x 6 – average rate over 10s
Other Paper Species
50mm/sec: ECG appears drawn out with wider complexes
* 1mm (small square) = 0.02s
* 5mm (large square) = 0.1s
Advantages of ECG
- Detect Arrhythmias
- Eval MEA – chamber enlargement
- Track response to therapy
Disadvantages of ECG
- Complexes possible even if dead
