Covidien Nellcor GR101704, Service Manual

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Theory of Operations
3-12 Service Manual
Figure 3-7. Clinically Significant Desaturation Patterns
The SPD parameter detects patterns of desaturation in adults that are indicative of
repetitive reductions in airflow through a patient's upper airway into the lungs. Rel-
ative reductions in a patient's minute ventilation over a period of time may cause
a progressive drop in alveolar partial pressure of oxygen, leading to arterial desat-
uration. If these decreases in ventilation are repetitive, they generate distinct pat-
terns in the saturation trend. Patterns of repetitive desaturation often develop
gradually over time, increasing in severity. Detection of patterns indicates that a
patient might be suffering progressively severe decrements in airflow that may
increase in acuity if left untreated.
Patterns of desaturation are multiple, sequential occurrences of a desaturation
followed by a resaturation. The SPD parameter qualifies patterns of desatura-
tion resulting from such repetitive reductions in airflow based on specific char-
acteristics.
The SPD parameter qualifies these patterns of desaturation over a period of six
(6) minutes. Depending on the sensitivity setting for SPD, patterns that persist
may result in an SPD alarm, alerting the caregiver to the condition.
•
The severity of the desaturation event (the depth of the desaturation during the
event) and the extent of the following resaturation
•
The regularity of the desaturation events (how often the pattern repeats)
•
The slope of the desaturation/resaturation trends that form the events
The SPD parameter communicates information to the caregiver about these
patterns of desaturation in a variety of ways with icons and alarms and in trend
data.