Respiratory acidosis with the small Storz-Hopkins bronchoscopes: occurrence and management

Carbon dioxide retention in the Storz rigid ventilating bronchoscope with the Hopkins lens system was investigated in the laboratory. The 3.5, 4.0, and 5.0 30-cm Storz bronchoscopes with a 3.95-mm (outside diameter) telescope lens were used in 10 mongrel dogs weighing between 8 and 15 kg. Significant (p less than 0.01) accumulation of arterial carbon dioxide tension (PaCO2) (respiratory acidosis) was observed after 5 and 10 minutes of ventilation through the 3.5 and 4.0 bronchoscopes, but no significant increase in PaCO2 was noted with the 5.0 bronchoscope. There was no significant change in arterial oxygen tension under the same conditions. Manual compression of the upper anterior abdominal wall during expiration was applied during bronchoscopy in 6 children. Arterial blood samples were taken before insertion of the bronchoscope and 5 minutes later with and without abdominal compression during expiration. A significant increase (p less than 0.05) in PaCO2 and a decrease in pH were observed after 5 minutes of the bronchoscopic procedure without manual compression of the abdominal wall, while no significant changes in PaCO2 were observed with abdominal compression.