Arterial blood pressure
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Measurement
History

Hales 1733
Riva-Rocci 1896
Cushing 1901

Direct method

Sites

Procedure

Components

Frequency response <40Hz/<20Hz required
Resonance, damping
Other uses- waveform, temperature, dye, blood sampling
Indirect methods
Mercury/aneroid manometer- palpation, oscillation, auscultation (Korotkoff sounds), Pulse detector, Doppler probe.
Oscillotonometer- two cuffs: inflation, pulse detection
Automatic measuring devices- single cuff for inflation & pulse detection

Indirect methods

Finapress device- cuff around finger, continuous measurement
Continuous arterial tonometry- continuous, pressure transducer over radial artery, its output is proportional to BP, periodic calibration needed.

Details
Direct method
Manometer with cuff
Oscillometry- Most common clinical method
Finapress method
Doppler probe/arterial tonometry

Errors NIBP
Detection of Korotkoff sounds
Cuff size
Zero/calibration errors

Errors IABP
Damping- high resonance and critical damping ideal; bubbles, canula, tap, tubing reduce the natural frequency of the system
Complaint catheter wall- damping
Clots- reduce resonant frequency- damping
Zeroing errors

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Addison's

Addison’s disease
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Addison’s

Glucocorticoid deficiency
Mineralocoeticoid deficiency usually
Primary, secondary
Acute, chronic, acute on chronic
Autoimmune mostly

clinically

Low BM
Postural hypotension
N V D weight loss
Pigmentation
Reduced hair
May not be obvious until stressed
Reduced calcium very rare

lab

Low Na, high K & urea
Low BM
Elevated ACTH
SST- 250 microgram, 0, 30, 60 min cortisol level, >580 ug excludes diagnosis
Reduced renin activity
Reduced aldosterone
adrenal crisis
Precipitated by stress
Hypotension, low Na, High K, low BM
Can present similar to septic shock
Hypovolaemic picture

treatment

ITU
Hydrocortisone 200 mg stat, 100 mg qds
Fluid resuscitation
Glucose resuscitation
Inotropes
Dexamethasone if diagnosis not clear, as doesn’t interfere with cortisol level.
hypercalcaemia
Increased bone resorption
Hyperparathyroidism
Malignancy- metastasis, PTH like peptides, lymphoma, mm
Paget’s disease
Immobilisation
Increased GIT abs-
Intake- milk alkalli, antacids, Ca
Excess Vit D- vit D, TB, sarcoidosis, lymphoma
Decreased Output-
Renal failure
Thiazides
FHH

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