Page 329 - Clinical Application of Mechanical Ventilation

Hemodynamic Monitoring 295

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TABLE 10-10 Conditions That Affect the SvO 2 Measurement
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SvO 2 Conditions Examples
Decrease Poor oxygen delivery Low cardiac output
Anemia
Hypoxic hypoxia
Excessive oxygen consumption Fever
Seizures
Increased metabolic rate
Increased physical activity
Stress
Pain
Depletion of venous oxygen Severe and prolonged
reserve hypoxia

Increase Technical problem Improperly wedged catheter
Increase in oxygen delivery T Cardiac output
CaO 2
T
Impaired oxygen utilization Sepsis
Cyanide poisoning
Decrease in oxygen consumption Hypothermia
Postanesthesia
Pharmacologic paralysis

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LESS-INVASIVE HEMODYNAMIC MONITORING

A number of less-invasive techniques for obtaining hemodynamic data have been
developed over the past decade. Pulse contour analysis is considered a less-invasive
technique because it requires an indwelling arterial catheter.

Pulse Contour Analysis

Earlier in this chapter, the shape and significance of the arterial pressure wave form
was discussed. The difference between peak systolic pressure and end-diastolic
pressure on this waveform is known as pulse pressure. Pulse contour analysis
pulse contour analysis: A less-
invasive method to calculate the (also known as arterial pressure waveform analysis) uses an arterial catheter and
stroke volume and stroke volume other data to derive the cardiac output. This is done by special algorithms using the
index by using the area under the
arterial pressure waveform and arterial pressure waveform, arterial vascular compliance, and specific patient data
specific patient data. to calculate the stroke volume and stroke volume index. The stroke volume and
stroke volume index are multiplied by the heart rate to yield the cardiac output and
cardiac index.

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