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Intratracheal oxygen administration during bronchoscopy in newborns: comparison between two different weight groups
Background:
The development of ultrathin fiberoptic bronchoscopy (FB) has made the examination of neonatal airways a practical possibility. The aim of this study was to assess the effects of intratracheal oxygen (ITO) administration on blood oxygenation and carbon dioxide (CO2) changes during FB in different body-weight infants.
Methods:
Newborns suspected of having airway problems, but in a stable cardiopulmonary condition were studied. An ultrathin (outside diameter, 2.2 mm) fiberoptic bronchoscope that was modified by adding an external tube (internal diameter, 0.3 mm; outside diameter, 0.64 mm) to deliver oxygen was used. For ITO administration, a low oxygen flow rate of 0.1 l/kg/min was delivered directly into the trachea. Oxygenation and CO2 measurements were obtained at five different stages: 1) just before FB (baseline); 2) with the tip of the bronchoscope at the supralarynx; 3) with the tip at the carina without ITO; 4) with the tip at the carina with ITO; and 5) 15 minutes after FB. Forty infants were studied completely and divided into two groups according to their body weight: 1) the light-weight group (< 2,500 g), 21 infants; and 2) the heavy-weight group (> or = 2,500 g), 19 infants.
Results:
In both groups, arterial blood oxyhemoglobin saturation and oxygen tension decreased significantly (p < 0.05) when the tip of the bronchoscope advanced from the nostril to the supralarynx, and further decreased (p < 0.01) when at the carina level. Small infants had greater decrements of both oxygenation measurements (p < 0.05) than the large infants. After ITO administration, both oxygenation measurements increased significantly (p < 0.001) and returned to baseline following FB. Both end tidal pressure of CO2 (P(ET)CO2) and arterial CO2 tension (PaCO2) significantly increased from the baseline when the FB tip was advanced from the supralarynx to the carina (p < 0.05). During ITO administration, the PaCO2 increased (p < 0.01) but the P(ET)CO2 decreased (p < 0.001). After FB, both CO2 measurements returned to baseline. The pH only decreased during ITO administration.
Conclusions:
We conclude that FB causes significant hypoxemia and hypercapnia in newborns, especially in underweight infants. Appropriate ITO can be considered a safe and beneficial technique for maintaining oxygenation during FB. P(ET)CO2 monitoring may mask true blood CO2 retention during ITO administration.