Oxygen Saturation

Pulse Oximetry

Figure 1- Differential Absoprtion of Oxy and Deoxy Hb Underlies Pulse Oximetry

Figure 2: Wavelength and absorption of carboxyhemoglobin (very similar to oxyhemoglobin) and methemoglobin


Regional Tissue Oxygenation



Transcutaneous CO2 Monitoring

Blood Pressure

Noninvasive Blood Pressure (NIBP)

Direct Arterial Blood Pressure Measurement (i.e. arterial line)

Normal increase in blood pressure due to pulse amplification/reflection

Interpreting the CVP waveform

-The normal CVP waveform (Figure 6) consists of various waves: 


    1) a wave: due to atrial contraction at the end of diastole

    2) c wave: due to the tricuspid valve bulging into the RA during isovolumic contraction

    3) x descent: due to atrial relaxation as the ventricle contracts

    4) v wave: due to filling of the atrium during systole

    5) y descent: due to emptying of the atria into the ventricle during diastole 

Various pathological processes can alter the CVP waveform:

    1) canon a waves:  large a waves seen with AV dissociation (ie JET) as the atrium contracts against a closed tricuspid valve

    2) loss of a waves: occurs in atrial fibrillation as there is no longer a significant atrial contraction

    3) prominent CV wave: occurs with tricuspid regurgitation; as the ventricle contracts, the regurgitation causes an increase in the C and V waves