There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
Electrosurgery, patient motion and some types of lighting can cause errors in saturation
readout; it is recommended that probes should be shielded from ambient lighting. Intravenous
dyes can introduce gross but transient errors, which may also be present in in vitro
measurements. Carboxyhaemoglobin causes overestimation of fractional saturation by
an amount less than, but possibly close to, the percent of carboxyhaemoglobin present.
Methaemoglobin causes the pulse oximeter readout to tend towards 85%. Fetal haemoglobin
and bilirubin introduce no significant error, although they may interfere with in
vitro measurements. Skin pigmentation can result in a slight decrease in accuracy.
Nail polish may cause up to 6% underestimation of saturation; it is recommended that
probes should be mounted sideways on fingers with nail polish or long nails. Adhesive
tape or a vinyl glove across the probe has no demonstrable effect on accuracy. A blood
sample should be analysed by a multiwavelength in vitro oximeter when an erroneous
pulse oximeter reading is suspected, although errors may be introduced in the in vitro
reading by fetal haemoglobin, bilirubin and intravenous dyes.
Five dogs were anesthetized, intubated, and ventilated with various mixtures of oxygen, nitrogen, and carbon monoxide. Each dog was monitored with arterial and pulmonary artery catheters, a transcutaneous PO2 analyzer, and two pulse oximeters. An IL-282 Co-oximeter was used to periodically measure arterial oxyhemoglobin (O2Hb) and carboxyhemoglobin (COHb) as percentages of the total hemoglobin. The PaO2, PaCO2, and pHa were measured in the same blood specimens using standard electrodes. When the inspired oxygen concentration was reduced in the absence of COHb, the pulse oximeter saturation (SpO2) estimated O2Hb with reasonable accuracy. COHb levels were then varied slowly from 0-75% in each dog. As the COHb level increased and oxyhemoglobin decreased, both pulse oximeters continued to read an oxygen saturation of greater than 90%, while the actual O2Hb fell below 30%. In the presence of COHb, the SpO2 is approximately the sum of COHb and O2Hb, and, thus, may seriously overestimate O2Hb. The pulse oximeter, as the sole indicator of blood oxygenation, should, therefore, be used with caution in patients with recent carbon monoxide exposure. On the other hand, transcutaneous PO2 falls linearly as COHb increases, and reaches about one-fifth of its initial value at the highest COHb levels despite the maintenance of constant arterial PO2.
scite shows how a scientific paper has been cited by providing the context of the citation, a classification describing whether it supports, mentions, or contrasts the cited claim, and a label indicating in which section the citation was made.