Evaluation of Endotracheal Tube Scraping on Airway Resistance.

BACKGROUND: Spontaneous breathing trials (SBTs) are used to assess the readiness for discontinuation of mechanical ventilation. When airway resistance (Raw) is elevated, the imposed work of breathing can lead to prolongation of mechanical ventilation. Biofilm and mucus build-up within the endotracheal tube (ETT) can increase Raw. Scraping the ETT can remove the biofilm build-up and decrease mechanical Raw. The primary aim of this study was to evaluate the impact of ETT scraping on Raw. The secondary aim was to determine whether decreasing Raw would impact subsequent SBT success. METHODS: Intubated, mechanically ventilated subjects were enrolled if they failed an SBT and had an Raw of > 10 cm H2O/L/s. SBT failure was based on institutional guidelines, and Raw was calculated by subtracting the difference between the measured peak and plateau pressures using a square flow waveform with an inspiratory flow set at 60 L/min. The endOclear device was inserted into the ETT and withdrawn per manufacturer's guidelines. Scraping was repeated until the ETT was cleared. Change in Raw was compared pre- and post-ETT scraping using a paired t test. A Mann-Whitney U test evaluated the difference in percentage change in Raw between SBT groups. RESULTS: Twenty-nine subjects completed the study. The mean pre- and post-ETT scraping Raw values were 15.17 ± 3.83 and 12.05 ± 3.19 cm H2O/L/s, respectively (P < .001). Subsequent SBT success was 48%; however, there was no difference in percentage change in Raw between subsequent passed SBT (18.61% [interquartile range 8.90-33.93%]) and failed SBT (23.88% [interquartile range 0.00-34.80%]), U = 78.5, z = -0.284, P = .78. No adverse events were noted with ETT scraping. CONCLUSIONS: This study demonstrated that ETT scraping can reduce Raw. The decrease in Raw post-ETT scraping did not affect subsequent SBT success.

The Effect of Nebulizer Position on Aerosolized Epoprostenol Delivery in an Adult Lung Model.

BACKGROUND: Aerosolized epoprostenol is an alternative for inhaled nitric oxide in the management of pulmonary arterial hypertension and possibly acute hypoxemia. Our objective was to determine differences in drug deposition based on different nebulizer positions in the ventilator circuit, using a vibrating mesh nebulizer. METHODS: An 8.0-mm inner diameter endotracheal tube (ETT) was connected to a training test lung, compliance of 30 mL/cm H2O, with a collecting filter placed at the ETT-test lung junction. A mechanical ventilator, heated wire circuit, and pass-over humidifier were utilized. A syringe pump continuously instilled a 15,000-ng/mL epoprostenol solution at 30, 50, and 70 ng/kg/min into the vibrating mesh nebulizer at all 4 positions. Tidal volumes (VT) were set at 4, 6, and 8 mL/kg for a 70-kg patient with breathing frequencies of 25, 16, and 12 breaths/min, respectively. Epoprostenol was eluted from the filters (no. = 180) and analyzed with ultraviolet-visible spectrophotometry at 205 nm to estimate drug deposition. RESULTS: Epoprostenol deposition increased significantly (P = .02) as the dosage increased from 30 ng/kg/min (median 4,520.0 ng, interquartile range [IQR] 2,285.0-6,712.2 ng) to 50 ng/kg/min (median 6,065.0 ng, IQR 3,220.0-13,002.5 ng) and 70 ng/kg/min (median 9,890.0 ng, IQR 6,270.0-16,140.0 ng). No significant difference was found between variations in ventilator settings. No difference in deposition was found between the humidifier inlet and outlet, but these positions resulted in greater deposition compared with the inspiratory limb and between the ETT and Y-piece. CONCLUSIONS: The greatest amount of mean epoprostenol deposition resulted with the nebulizer placed at the humidifier inlet or outlet in a ventilator with bias flow.

Vibrating Mesh Nebulizer Compared With Metered-Dose Inhaler in Mechanically Ventilated Subjects.

BACKGROUND: The impact of various aerosol delivery devices on patient outcomes during mechanical ventilation is unknown. If one method of delivery results in a higher ventilator-associated pneumonia (VAP) rate than another, multiple patient outcomes may be affected. This study aimed to determine whether there was a difference in VAP occurrence and patient outcomes (days receiving ventilation and in-hospital mortality) between the vibrating mesh nebulizer (AeroNeb Solo) and the metered-dose inhaler (MDI). METHODS: This retrospective study reviewed medical records for all mechanically ventilated, adult patients with an order for aerosol treatment from August 2011 to August 2013. The hospital converted from MDI to vibrating mesh nebulizers in August 2012, and data were gathered 1 y before/after conversion. Excluded were patients with a tracheostomy, patients who were mechanically ventilated for <24 h, patients who received a combination of nebulizer and MDI treatments, or patients who were re-intubated. RESULTS: Two hundred twenty-eight subjects were included. Forty-eight (21%) received treatment with an MDI, and 180 (79%) were treated with the vibrating mesh nebulizer. Descriptive data did not significantly differ for age or APACHE II (Acute Physiology and Chronic Health Evaluation II) scores between the groups but did for sex (P = .03). Difference in median days receiving ventilation for the MDI (5 d, interquartile range 3.0-8.5 d) and the vibrating mesh nebulizer (6 d, interquartile range 4.0-10.0 d) was not statistically significant. No correlation was found between the use of either device and the primary outcomes of VAP and in-hospital mortality. In multivariable logistic regression analysis, the number of days receiving ventilation increased the odds of VAP (odds ratio [OR] 1.3, 95% CI 1.14-1.49, P < .001) and mortality (OR 1.12, 95% CI 1.04-1.21, P = .002). Higher APACHE II scores increased the odds of mortality (OR 1.05, 95% CI 1.001-1.092, P = .044). CONCLUSION: We found no association between an MDI or vibrating mesh nebulizer and our primary outcomes, days receiving ventilation, in-hospital mortality, or VAP, in mechanically ventilated subjects.