Nellcor Oximax NPB-40, Operator'S Manual

Page: 100 / 161

Performance Considerations
92
Inaccurate measurements can be caused by:
• prolonged and/or excessive patient movement
• venous pulsations
• intravascular dyes, such as indocyanine green or
methylene blue
• externally applied coloring agents (nail polish, dye,
pigmented cream)
• defibrillation
Dysfunctional Hemoglobins
Dysfunctional hemoglobins, such as carboxyhemoglobin,
methemoglobin, and sulphemoglobin, are unable to carry
oxygen. SpO
2
readings may appear normal; however, a
patient may be hypoxic because less hemoglobin is
available to carry oxygen. Further assessment beyond
pulse oximetry is recommended.
Anemia
Anemia causes decreased arterial oxygen content.
Although SpO
2
readings may appear normal, an anemic
patient may be hypoxic. Correcting anemia can improve
arterial oxygen content. The monitor may fail to provide
an SpO
2
if hemoglobin levels fall below 5 gm/dl.