BP Flashcards
Systolic and diastolic
- systolic= max press on vessel walls from blood during ventricle contraction.
- diastolic= arterial pressure during ventricle filling, maintained by elasticity and compliance of vessel wall. Lowest immediately before next cycle.
ICU
Can measure with intra arterial catheter with pressure sensor.
Korotkoff sounds
Produced between systole and diastole because artery collapses completely and re opens with each heart beat= snapping or knocking sound.
-first phase 1 sound during cuff deflation indicates systole. Tap/sharp thud.
-phase 2 soft swishing
-phase 3 crisp sound, softer thud than phase 1
-phase 4 sound is muffling as pressure is reduced. Can persist and not disappear (count this as diastolic BP). Soft blowing sound.
disappearance of sound= diastolic BP.
-phase 5 silence. Below diastolic pressure.
Arm differences
If over 10mmHg difference between arms- SCA disease. Use the highest one.
Cuff size
Bladder should be 80% of length and 40% width of upper arm circumference.
Too small- overestimate.
Too big- underestimate.
Auscultatory gap
20% of elderly HTN patients have korotkoff sounds which appear at systolic pressure then disappear for an interval between systolic and diastolic.
Korotkoff sounds temporarily inaudible between pahse 2 and 3 for around 20mmHg before the reappearing.
So pump to 30mmHg over the estimate to avoid missing auculatatory gap and getting an underestimate of systolic BP.
If first appearnace missed then can get falsely low systolic BP.
Avoid this by palpating systolic pressure first.
Arm level
Patients elbow should be level with heart.
Or change hydrostatic pressure= alter systolic BP.
Postural change
Standing= pulse increase by 11, systolic BP fall by 3-4 mmHg, diastolic BP 5-6 mmHg in normal person.
BP stabilises after 1-2 mins.
Check after standing for 2mins- drop of over 20=postural hypotension.
AF
Beat to beat variability makes measurement difficult.
May need to repeat.
Deflate at 2mmHg per beat.
Normally deflate at 2/3mmHg per second.
