Accuracy of Nasopharyngeal Probes Clinical Trial
Official title:
Optimal Positioning of Nasopharyngeal Temperature Probes in Pediatric Patients: A Prospective Cohort Study
Core temperature is of greatest interest in terms of temperature monitoring as it is thought
to represent the temperature of the vessel-rich groups that are instrumental in
thermoregulatory control. The nasopharynx is among the recommended temperature monitoring
sites for core body temperature. It is the part of the pharynx that lies above the soft
palate. Anteriorly it opens to the nasal cavities through the choanae; inferiorly it
communicates with the oropharynx through the pharyngeal isthmus. Nasopharyngeal temperatures
are accurate in adults when probes are inserted between 10 and 20 cm.
The optimal depth for insertion of nasopharyngeal probes remains poorly defined in infants
and children. While some data suggest that anthropometric measurements are well correlated
with endoscopic measurements in infants based on weight, the accuracy of temperature
measurements at these and other distances has yet to be quantified. The investigators thus
propose to determine the insertion depth (or range of depths) for nasopharyngeal temperature
proves that best approximate core temperature as measured in the distal esophagus in infants
and children of various sizes. The comparison site will be the distal esophagus since there
is broad consensus that the distal third of the esophagus it at core-body temperature.
For the two groups of infants aged up to twelve months, the nasopharyngeal probe will be
marked with indelible ink from 2-10 cm in 1-cm increments and inserted 10 cm. For the two
groups of children between 1 and 5 years, the nasopharyngeal probe will be marked with
indelible ink from 2-15 cm in 1.5-cm increments and inserted 10 cm. For older children, a
nasopharyngeal probe will be marked with indelible ink from 2 to 20 cm at 2 cm increments
from its tip, and inserted 20 cm.
Both nasopharyngeal and esophageal temperatures will initially be recorded 30 minutes after
induction of anesthesia. Nasopharyngeal probes will then be withdrawn at the designated
increment for each age group and will be equilibrated for 5 minutes before the temperature is
recorded. Thereafter, the nasopharyngeal withdrawal sequence will be repeated. The number of
measurement will depend on the initial depth of insertion, with measurements continuing until
only 2 centimeters remain in the nostril.
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