Alveolar ventilation in children during flexible bronchoscopy

Background: Hypoxia and hypercarbia complicate flexible bronchoscopy (FB). Unlike oxygenation by pulse-oximetry, alveolar ventilation is not routinely monitored during FB. The aim of this study was to investigate ventilation in children undergoing FB by measuring carbon-dioxide (CO₂) levels using the transcutaneous technique. Methods: Children admitted for FB were recruited. In addition to routine monitoring, transcutaneous CO₂ (TcCO₂) levels were recorded. All were sedated using the same protocol. Results: Ninety-five children were studied. There was no association between peak TcCO₂ or rise in TcCO₂ and age, weight percentile, bronchoscope size, or diagnosis. Median baseline TcCO₂ was 36 mmHg (IQR 32,40), median peak TcCO₂ was 51 mmHg (IQR 43,62) with median TcCO₂ rise of 17 mmHg (IQR 6.5,23.7). A rise of 15 mmHg or higher was recorded in 55% (n = 52) patients. Children requiring total propofol dose over 3.5 mg/kg had a significantly higher TcCO₂ peak of 57.6 mmHg (IQR 47.8,66.7) compared to 47.1 mmHg (IQR 40,57) (P = 0.004) and a higher rise in TcCO₂ 22.5 mmHg (IQR 17,33.9) compared to 13.6 mmHg (6,22) (P = 0.001). Results were not affected by intranasal midazolam and broncho-alveolar lavage. No complications were reported. Non clinically significant (i.e., not lower than 90%) brief drops in oxygen saturation were observed. Conclusions: A large proportion of children undergoing FB have significant alveolar hypoventilation indicated by a rise in TcCO₂. Monitoring ventilation with TcCO₂ is feasible and should be added during FB particularly in cases that are expected to require large amounts of sedation and patients susceptible to complications from respiratory acidosis. Pediatr Pulmonol. 2016;51:1177–1182.