NIBP

Question 1

General MOA of Oscillometric BP

Answer 1

Automatically inflates, deflates cuff – oscillometer analyzes fluctuations of pressure within cuff as slowly deflated

SAP, DAP: first, last pulse-assoc fluctuations in cuff pressure

MAP: cuff pressure at which max pressure oscillations occur

Question 2

Accuracy of NIBP - European Society for Hypertension International Protocol

Answer 2

require certain level of accuracy versus some gold standard, generally DBP – strict guidelines
* 2/3: within 5mm Hg 73%, 10mm Hg 87%, 15mm Hg 96%
* Hypotensive, hypertensive, normal patient spectrum: within 5 65%, 10 81%, 15 93%

Question 3

ACVIM Required Accuracy for BP Measurement

Answer 3

ACVIM: within 10mm Hg >50%, within 20mm Hg >80%

Question 4

Kim et al 2022 (VAA)

Answer 4

eval agreement btw oscillometric BP from tongue vs IBP; tongue vs tail vs pelvic limb in 8 beagle dogs

Mean bias, standard deviation between IBP, OBP met veterinary, human standards for MAP and DAP; SAP - unacceptable agreement for all cuff sites

During hypotension, tongue showed largest percentage of absolute difference in relation to IBP for SAP, MAP, DAP vs tail, tongue

Reliable for MAP, DAP in normotensive animals, relatively suitable site during hypotension

Question 5

Pros - Oscillometric

Answer 5

• Non-invasive
• Easy to use, automatic
• Portable
• SAP, DAP, MAP

Question 6

Cons of Oscillometric

Answer 6

• Small vessel size, motion – interference
• Not continuous
• Less reliable/accurate –overestimates MAP in hypotensive patients, underestimates SAP
• More inaccurate in presence of arrhythmias
• $$$ vs Doppler

Question 6

Cons of Oscillometric

Answer 6

• Small vessel size, motion – interference
• Not continuous
• Less reliable/accurate –overestimates MAP in hypotensive patients, underestimates SAP
• More inaccurate in presence of arrhythmias
• $$$ vs Doppler

Question 7

Sphygmamometry

Answer 7

application of occlusive cuff over artery in cylindrical appendage

Inflation of cuff – pressure to underlying tissues, occlusion of BF when cuff pressure > SAP

Cuff pressure gradually released, blood intermittently begins to flow when cuff pressure < SAP

Question 8

As cuff is deflated…

Answer 8

small positive deflections of cuff pressure observed each time pulse wave hits cuff
* SAP: manometer pressure at which positive oscillation begins
* Oscillations maximal at MAP
* Diminute at ~DAP

Question 9

Cuff pressure < SAP

Answer 9

blood flows past cuff – palpated or ausculted (Korotkoff sounds, blood flow sounds)

Question 10

Cuff pressure at which first palpable pulse or auscultated tapping sound heard?

Answer 10

SAP

Question 11

Locations for NIBP cuff placement

Answer 11

Antebrachium, tail, proximal to tarsus, DP

Question 12

What is ABP?

Answer 12

arterial hydrostatic pressure vs Patm
o Determined by arterial compartment blood vol (balance btw inflow – CO, outflow – diastolic run off), arterial compartment wall tone

Question 13

SAP

Answer 13

highest intraarterial wall pressure of each cycle

Question 14

DAP

Answer 14

lowest pressure prior to next heart beat

Question 15

Normal BP in Awake Dogs, Cats

Answer 15

Dogs, Cats: SAP 100-160mm Hg, MAP 60-100, DAP 80-120

Question 16

MAP

Answer 16

average area under pulse pressure waveform, = 1/3 (SAP-DAP) + DAP
o MAP = SV * HR * SVR
o Represents average upstream pressure for tissue perfusion, average afterload to heart

Question 17

Normal BP Horses, SR

Answer 17

o Horses, SR: SAP 90-130, MAP 60-90, DAP 70-110

Question 18

Definition of Hypotension

Answer 18

MAP <60mm Hg, SAP <80mm Hg – compromised cerebral, coronary perfusion
* Hypertension:

Question 19

Severe, acute hypertension

Answer 19

edema, hemorrhage anywhere (brain, lungs)
 MAP >140mm Hg, SAP >180mm Hg

Question 20

Chronic Hypertension

Answer 20

consequences of high cardiac afterload, ocular retinopathy/choroidopathy, retinal detachment, encephalopathy, renal dz
 MAP >120mm Hg, SAP >160

Question 21

What is the recommended cuff circumference vs limb?

Answer 21

30-40%

Question 22

Cuff that is too narrow?

Answer 22

Overestimation of BP

Question 23

Cuff that is too wide?

Answer 23

Underestimation of BP

Question 24

Cuff that is too tight?

Answer 24

Restriction of BF- overestimation

Question 25

Cuff that is too loose?

Answer 25

Underestimation of BP

Question 26

Doppler - MOA

Answer 26

Pair of piezoelectric crystals over artery distal to cuff

One crystal transmits US energy into tissue: US signal phase shifted by movement of underling tissue (Doppler shift), transmitted back to receiving crystal

Change in frequency btw transmitted, received signals detected – transmitted to audible signal

Question 27

What is the first audible signal detected by the Doppler?

Answer 27

SAP in mammals

Change in frequency btw transmitted, received signals detected - transmitted to audible signals

Question 28

Secondary Sound on Doppler

Answer 28

double blood flow assoc with each heart beat, cuff pressure in dicrotic notch of PP waveform
 NOT diastolic pressure
 Subsequent transient rise in BP > cuff pressure, flow transiently recurs

Question 29

Moll et al 2018 (VAA)

Answer 29

poor agreement btw DOP, IBP in anesthetized dogs <5kg

Question 30

Pros - Doppler

Answer 30

• Non-invasive
• Audible
• Use on any species
• Inexpensive
• Rechargeable, portable