ISSN:
1573-2614
Keywords:
Cardiac anesthesia
;
esophagus
;
monitoring
;
oximetry
;
oxygen saturation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Computer Science
,
Medicine
Notes:
Abstract Objective.Pulse oximetry (SpO2) is the noninvasivestandard for monitoring arterial oxygen saturation in patients undergoinganesthesia, but is subject to external interference by motion artifact,peripheral vasoconstriction, and low cardiac output. We hypothesized thatoximetry signals could be acquired from the esophagus when peripheral pulseoximetry is unobtainable. Therefore, we tested an esophageal stethoscope whichincorporates transverse oximetry photodetectors and emitters in patientsundergoing coronary bypass surgery. Methods.Immediately afterinduction of general anesthesia in 10 coronary artery bypass (CABG) patients,Criticare and Nellcor digital probes were positioned on the left hand,concurrent with placement of an esophageal SpO2 probe. A computerrecorded 5,910 matched oximetry signals every 15 sec during an average of 2.5hrs. All SpO2 measurements were before, and immediately afternon-pulsatile, hypothermic cardiopulmonary bypass. Data represent thepercentage (median value [range]) of the total monitored time thata SpO2 value was displayed. Results.The Nellcor (99.8%,range 6.5–100%) and Criticare (99.7%, range 36.6–100%) acquiredand displayed saturation signals more frequently (p= 0.003) than theesophageal monitor (75.3%, range 42.1–95.8%). The two standard digitaloximeters had a mean difference of 0.9%, with a standard deviation of thedifferences of 0.9. The esophageal probe had a mean difference of −5.2%and −4.8%, with standard deviation of differences of 8.0 and 7.7(compared to the Nellcor and Criticare monitors, respectively). Asecond-generation prototype shielded from electrocautery interference wastested in an additional 4 patients. The shielded prototype displayed signalsmore frequently (96.7%, range 68.4–100%) than the original esophagealprototype. Conclusions.Digital pulse oximetry failure is common inCABG patients, probably because of marginal cardiac output and peripheralvasoconstriction associated with hypothermia. Our study could not confirm thatesophageal technology, which utilizes the esophagus as a site oftransflectance oximetry, was superior to conventional digital pulse oximetry.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009941610320
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