End-tidal carbon dioxide monitoring during flexible fiberoptic bronchoscopy

Abstract

In recent years, flexible fiberoptic bronchoscopy (FFB) has been applied for diagnostic and some therapeutic purposes. During FFB and even in the presence of supplemental oxygen, hypoventilation leading to hypoxia and desaturation may occur; this is aggravated by the use of suction. Arterial oxygen saturation is usually monitored with pulse oximetry Spo₂) during FFB; END-TIDAL Pco₂) (ET-Pco₂) monitoring is not routinely used. Two-hundred patients were studied between May 1998 till April 2003, at the divisions of chest surgery and pulmonolgy at King Hussein Medical Center, (khmc). Their ages were 53±19 years (mean±SD). They underwent FFB and received supplemental oxygen during various stages of FFB: 1-before and during instillation of hdocaine 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 significantly decreased from Spo₂ using a pulse oximeter simultaneously and the results were recorded. Mean ET-Pco₂ significantly decreased from 28.7±4.5 mmHg before FFB to 28±5.7 mmHg, 27±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 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 are recommended.

Keywords: end-tidal Pco₂, fiber optic bronchoscopy, Spo₂

Mary Slessor Journal of Medicine Vol. 5(2) 2005: 1-4