Anesthesia Monitors Review

Auto BP Cuff

• There are many types of algorithms that go into generating the numbers seen on the screen. All of them use oscillations and plot a curve/give values.

General guideline is no more than 20-30% drop in MAP from baseline

Sitting Position: BP decreases by 0.74mmHg per cm

CVP

• Loss of a Wave:
  • A fib or V pacing without atrial contraction
• Large a Wave:
  • Atria emptying against high resistance
  • Tricuspid stenosis, diastolic dysfx, ischemic heart, RVH, AV dissociation, junctional, V paced, PVC
• Large v Wave:
  • Tricuspid regurg

EKG

PA Catheter

When PAOP Does NOT Predict LVEDV

• Overestimates
  • Impaired LV compliance ie. ischemia
  • Mitral valve disease
  • Left to right cardiac shunt
  • Tachycardia
  • PPV
  • PEEP
  • COPD
  • Pulmonary hypertension
  • Non west zone III placement of PAC
• Underestimates
  • Aortic insufficiency

Pulse Oximetry and the Beer Lambert Law

Important to note that red wavelength is 600 and infra red is 900. The Beer Lambert law discusses absorption of light and then a converstion into a saturation percentage.

• Variables:
  • A = absorbance
  • ε = molar absorptive coefficient
  • C = concentration (moles/liter)
  • L = length of light path
  • $I_o$ = Incident light
  • I = Transmitted light

\[{A} = {\varepsilon C l} = {log{({I_o \over I})}}\]