Respiratory acidosis during bronchoscopy-guided percutaneous dilatational tracheostomy: impact of ventilator settings and endotracheal tube size

Abstract

Background: The current study investigates the effect of bronchoscopy-guided percutaneous dilatational tracheostomy (PDT) on the evolution of respiratory acidosis depending on endotracheal tube (ET) sizes. In addition, the impact of increasing tidal volumes during the intervention was investigated. Methods: Two groups of ICU-patients undergoing bronchoscopy-guided PDT with varying tidal volumes and tube sizes were consecutively investigated: 6 ml/kg (N = 29, mean age 57.4 ± 14.5 years) and 12 ml/kg predicted body weight (N = 34, mean age 59.5 ± 12.8 years). Results: The mean intervention time during all procedures was 10 ± 3 min. The combination of low tidal volumes and ETs of 7.5 mm internal diameter resulted in the most profound increase in PaCO 2 (32.2 ± 11.6 mmHg) and decrease in pH-value (− 0.18 ± 0.05). In contrast, the combination of high tidal volumes and ETs of 8.5 mm internal diameter resulted in the least profound increase in PaCO 2 (8.8 ± 9.0 mmHg) and decrease of pH (− 0.05 ± 0.04). The intervention-related increase in PaCO 2 was significantly lower when using higher tidal volumes for larger ET: internal diameter 7.5, 8.0 and 8.5: P > 0.05, =0.006 and = 0.002, respectively. Transcutaneous PCO 2 monitoring revealed steadily worsening hypercapnia during the intervention with a high correlation of 0.87 and a low bias of 0.7 ± 9.4 mmHg according to the Bland-Altman analysis when compared to PaCO 2 measurements. Conclusions: Profound respiratory acidosis following bronchoscopy-guided PDT evolves in a rapid and dynamic process. Increasing the tidal volume from 6 to 12 ml/kg PBW was capable of attenuating the evolution of respiratory acidosis, but this effect was only evident when using larger ETs.

Endotracheal Tube Size in Critically Ill Patients

“…Although the effect of appropriate ETT size on critical care outcomes is a relatively understudied question, a few groups have investigated the association of tube size with ventilator weaning and respiratory mechanics. [10][11][12] Overall, it has been shown that smaller diameter ETTs are associated with an increase in various respiratory metrics, including airway pressures and respiratory frequency to tidal volume ratios. [10][11][12] The effect of tube diameter on these metrics may be the driver behind the increased intubation duration noted in our study, although we did not observe a significant relationship between ETT size group and PIP.…”

“…[10][11][12] Overall, it has been shown that smaller diameter ETTs are associated with an increase in various respiratory metrics, including airway pressures and respiratory frequency to tidal volume ratios. [10][11][12] The effect of tube diameter on these metrics may be the driver behind the increased intubation duration noted in our study, although we did not observe a significant relationship between ETT size group and PIP.…”

“…Although the effect of appropriate ETT size on critical care outcomes is a relatively understudied question, a few groups have investigated the association of tube size with ventilator weaning and respiratory mechanics . Overall, it has been shown that smaller diameter ETTs are associated with an increase in various respiratory metrics, including airway pressures and respiratory frequency to tidal volume ratios .…”

Percutaneous tracheostomy: Comparison of three different methods with respect to tracheal cartilage injury in cadavers—Randomized controlled study

“…tracheal puncture with partially lost airway) shorter and probably safer. Another important aspect is, that with good visibility bronchoscopy is nearly unnecessary, thus it is easier to avoid the significant rise of PaCO 2 and consequent respiratory acidosis which occurs during bronchoscopy even when applying increased tidal volume and large diameter endotracheal tube (51). The obvious limitation of our study is that PDTs were made in cadavers, which could influence cartilage flexibility, so cadaver's tracheal cartilages could be more rigid than in case of living tissue.…”

Safety of percutaneous dilatational tracheotomy (PDT) with the rigid tracheotomy endoscope (TED): a 6-month follow-up multicenter investigation

“…Fiberoptic tracheo-bronchoscopy remains the standard method to perform PDT [1,2]. Obstruction of the endotracheal tube due to flexible endoscope during PDT may cause ventilation problems with subsequent hypoxemia, hypercarbia, increased intracranial pressure and pneumothorax [5]. In order to provide better visualization of the tracheal anatomy and improve airway management and safety during the PDT procedure, the rigid tracheotomy endoscope (TED) was introduced [6].…”