Background-In recent years, flexible fiberoptic bronchoscopy (FFB) has been applied
for diagnostic and therapeutic purposes. Premedication along with the passage of FFB into
the airway, even in the presence of supplemental oxygen, may cause hypoventilation
leading to hypoxia and desaturation. Arterial oxygen saturation is usually monitored with
pulse oximetry (Spo2) during FFB; END-tidal Pco2 (ET-Pco2) monitoring is not routinely used.
Methods-Two-hundred patients, ages 53±19 years (mean±SD), underwent FFB and
received supplemental oxygen during various stages of FFB: 1-before and during instillation
of lidocaine on the vocal cords, 2-during passage of instrument into the trachea, RMB, IMB,
3-during bronchoalveolar lavage, bronchial biopsy, transbronchial biopsy (TBB), and 4-at
the final stages of FFB. ET-Pco2 changes were studied with a capnograph and Spo2 using a
pulse oximeter simultaneously and the results were recorded.
Results-Mean ET-Pco2 significantly decreased from 28.7±4.5 mmHg before FFB to 28±5.7
mmHg, 27.9±5.5 mmHg, 27.5±5.6 mmHg, 27.1±4.5 mmHg, 27.9±5.3 mmHg during
bronchoscopy of the right main bronchus (RMB), left main bronchus (LMB), bronchial
washing, bronchial biopsy and transbronchial biopsy (TBB), and at the termination of FFB,
respectively (p<0.05). In 118 patients (59%), the decrease of ET-Pco2 was equal to or greater
than 4 mmHg; in 105 patients (52.5%) the amount of decrease in Spo2 was 5% and in 32
patients (16%), Spo2 decreased 10%. No correlation was found between decreasing ETPco2
and Spo2 during the procedure.
Conclusion- ET-Pco2 and Spo2 decreased during bronchoscopy. We also speculate that
this reflects airway obstruction by the instrument. Further studies and more experimental
analysis in this field is recommENDed