VOLUMETRIC CAPNOGRAPHY FOR RESPIRATORY MONITORING OF PATIENTS DURING ROUTINE COLONOSCOPY WITH ROOM-AIR AND CARBON DIOXIDE INSUFFLATION

Capnografia volumétrica para monitoração respiratória de pacientes submetidos a colonoscopia diagnóstica com insuflação de ar comprimido e gás carbônico

ABSTRACT

Background:

Capnography and carbon dioxide (CO₂) insufflation during gastrointestinal endoscopy under sedation are associated with safety and comfort improvements, respectively. Capnography can provide early detection of apnea and hypoxemia, whereas CO₂ insufflation causes lower periprocedural discomfort. This is the first study to report the application of volumetric capnography in colonoscopy.

Objective:

This study aimed to evaluate the use of volumetric capnography with room air (RA) and CO₂ insufflation during routine colonoscopy.

Methods:

In this prospective cohort study, 101 patients who underwent routine colonoscopy under sedation with volumetric capnography monitoring were included. Insufflation with RA was used to distend the intestinal lumen in group 1 (n=51), while group 2 (n=50) used CO₂ insufflation. The primary endpoints were episodes of hypoxia, alveolar hypoventilation, and end-tidal CO₂ (EtCO₂). The secondary endpoints were tidal volume per minute, consumption of sedation medications, and post-procedure pain using the Gloucester modified pain scale.

Results:

The number of episodes of hypoxia (SpO₂<90%) was similar between the groups: four episodes in Group 1 and two episodes in Group 2. The duration of hypoxia was significantly longer in group 2 (P=0.02). Hypoalveolar ventilation (EtCO₂) occurred more frequently in Group 2 than in Group 1 (27 vs 18 episodes, P=0.05). Regarding EtCO₂, Group 2 showed higher values in cecal evaluation (28.94±4.68 mmHg vs 26.65±6.12 mmHg, P=0.04). Regarding tidal volume per minute, Group 2 had significantly lower values at the cecal interval compared to Group 1 (2027.53±2818.89 vs 970.88±1840.25 L/min, P=0.009). No episodes of hypercapnia (EtCO₂ > 60 mmHg) occurred during the study. There was no difference in the consumption of sedation medications between the groups. Immediately after colonoscopy, Group 2 reported significantly less pain than Group 1 (P=0.05).

Conclusion:

In our study, volumetric capnography during colonoscopy was feasible and effective for monitoring ventilatory parameters and detecting respiratory complications. CO₂ insufflation was safe and associated with less pain immediately after colonoscopy.

Keywords:
Colonoscopy; capnography; carbon dioxide; volumetric capnography; safety