clinical measurement

Question 1

what is a DINAMAP and how does it work

Answer 1

A DINAMAP (Device for Indirect Non-Invasive Mean Arterial Pressure) is an automated oscillometric blood pressure (BP) monitor used in hospitals and clinical settings

-Mean Arterial Pressure (MAP): Determined at the point of maximum oscillations.
-Systolic BP: Estimated when oscillations first increase significantly.
-Diastolic BP: Estimated when oscillations diminish significantly.

Question 2

what happens if bp cuff is too small or too large

Answer 2

too small- overestimates
too large-underestimates

correct- cuff bladder that is:
width 40% of arm circumference
length- 80% of arm circumference

Question 3

what is the effect of damping on accuracy of the waveform

What can cause damping

Answer 3

-damping reduces overshoot and resonance
-Optimal damping factor is 0.7

> 1 =over-damping

Damping can be caused by:
-air bubble,
-clot
-very compliant diaphragm and tube. Increased

damping lowers the systolic pressure and elevates the diastolic pressure. The monitoring system should have an optimal damping value of 0.64.

Question 4

Beer Lambers law

Answer 4

light transmitted through a substance decreases exponentially with increasing distance and concentration

e.g twice the thickness of travel through => decrease twice as much in light intensity exiting as twice the absorption occurs.

when concentration doubles, twice absorption occurs, with 2 x decrease in L1 (light intensity exiting)

Question 5

absorption of deoxy and oxy wavelengths

isobestic point
effect of metHb, COHb, methylene blue

Answer 5

oxy 940
deoxy 660
isobestic point =805 nm (deoxy and oxy cross)

metHb around 85% regardless
methylene blue- under read
COHb- falsely high (absorbs identical to HbO2 at 660