Oxygen insufflation through the bronchoscope channel for sedation-induced hypoxia: safe and effective

Abstract

Objectives: To evaluate both efficacy and safety parameters for insufflation through the bronchoscope as a method of recovery from sedation-induced hypoxia. To explore parameters applicable to use in human beings using an animal model.

Materials and methods: Two adult pigs were sedated enough to depress respiratory drive. The effects of insufflation at 15 l/min (the upper limits of flow that might be used clinically) were then evaluated. Pressure and volume responses to bronchoscopy during intubation and without an endotracheal tube in place were recorded. Several assays were performed for each scenario, with each animal acting as its own control. Recovery from hypoxemia using insufflation was compared with recovery using mechanical ventilation.

Results: Insufflation was effective, with rapid increases in fraction of inspired oxygen (FIO₂), saturation, and partial pressure of arterial oxygen (PaO₂). The rate of recovery using insufflation was faster than that from institution of mechanical ventilation. Insufflation in an intubated animal with cuff inflated led to a rapid and dangerous rise in pressure. With balloon deflated, there were no adverse pressure consequences from insufflation via the endotracheal tube at a rate of 15 l/min.

Conclusion: Insufflation through the bronchoscope for episodes of sedation-induced hypoxia should be safe and effective as long as not delivered within a closed system.

Keywords: bronchoscopy; hypoxemia; insufflation; sedation.

Figure 1.

Sequence of events for induced desaturation with rescue. Re-institution of mechanical ventilation for rescue was compared with insufflation. For insufflation, ETT was in place with balloon deflated (animal A) or removed (animal B).

Figure 2.

Pressure sequelae of insufflation using large bronchoscope within a #7.5 Shiley ETT. Baseline was obtained during mechanical ventilation with bronchoscope in ETT. Ventilation was then ceased, and insufflation values were obtained with insufflation alone and ETT balloon deflated (1–4) or inflated (5). For each assay, the animal served as its own control. Given the adverse pressure sequelae of inflation with balloon inflated, this assay was terminated at 3 s and not repeated.

Figure 3.

FIO₂ sequelae of insufflation for 10 s at 15 l/min. For each assay, the animal served as its own control.

Figure 4.

Rescue studies. Re-institution of mechanical ventilation (at an FIO₂ of 21%) was compared with oxygen insufflation at 15 l/min. Each animal served as its own control for each assay.

Figure 5.

Arterial blood gasses were collected at approximate nadir of saturation (1) and after rescue (2) via insufflation (left side) versus mechanical ventilation (right side) (four sets were collected for insufflation and three sets for ventilation).