David L. Vines

Medication adherence issues in patients treated for COPD

Although medical treatment of COPD has advanced, nonadherence to medication regimens poses a significant barrier to optimal management. Underuse, overuse, and improper use continue to be the most common causes of poor adherence to therapy. An average of 40%–60% of patients with COPD adheres to the prescribed regimen and only 1 out of 10 patients with a metered dose inhaler performs all essential steps correctly. Adherence to therapy is multifactorial and involves both the patient and the primary care provider. The effect of patient instruction on inhaler adherence and rescue medication utilization in patients with COPD does not seem to parallel the good results reported in patients with asthma. While use of a combined inhaler may facilitate adherence to medications and improve efficacy, pharmacoeconomic factors may influence patient’s selection of both the device and the regimen. Patient’s health beliefs, experiences, and behaviors play a significant role in adherence to pharmacological therapy. This manuscript reviews important aspects associated with medication adherence in patients with COPD and identifies some predictors of poor adherence.

Perceived Satisfaction With Long-Term Oxygen Delivery Devices Affects Perceived Mobility and Quality of Life of Oxygen-Dependent Individuals With COPD

BACKGROUND: Although routine physical activity for individuals with COPD is recommended, there are inherent limitations of available oxygen delivery devices that may result in hypoxemia during activity. Changes in Medicare laws have resulted in an increased use of oxygen cylinders and a reduction in the use of liquid oxygen devices. The aim of this survey was to assess the impact of perceived satisfaction with various oxygen delivery devices on perceived mobility and quality of life (QOL) of oxygen-dependent subjects with COPD. METHODS: A survey was developed to measure perceived satisfaction with current portable oxygen delivery devices, perceived mobility, and perceived QOL. The survey was deployed via a link posted on the COPD Foundations COPD360SOCIAL social media site for 5 weeks, which resulted in the recruitment of 529 participants, of which 417 were included in the data analysis. RESULTS: Quantile regression analysis revealed that the median perceived device satisfaction score was significantly higher in the liquid oxygen device group (P < .001) compared with the portable oxygen cylinder and portable oxygen concentrator (POC) groups. The median perceived mobility score was significantly higher in the liquid oxygen device group (P < .001) compared with the portable oxygen cylinder group, but not the POC group. The median QOL score was significantly higher in the liquid oxygen device group (P < .001) compared with the POC and portable oxygen cylinder groups. Moreover, partial least-squares structural equation modeling regression analysis showed that perceived mobility is significantly affected by perceived satisfaction with the long-term oxygen therapy (LTOT) device (adjusted R2 = 0.15, P < .001), and perceived QOL is significantly affected by both perceived satisfaction with the LTOT device and perceived mobility (adjusted R2 = 0.45, P < .001). CONCLUSIONS: For individuals with COPD requiring LTOT, perceived satisfaction with a portable LTOT device significantly and positively affects perceived mobility and QOL.

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.

Role of Integrated Pulmonary Index in Identifying Extubation Failure

BACKGROUND: The integrated pulmonary index (IPI) utilizes an algorithm based on the measurement of end-tidal carbon dioxide, breathing frequency, heart rate, and oxygen saturation to provide an assessment of the patients ventilatory status. This clinical trial was designed to determine whether lower IPI values were associated with extubation failure. METHODS: This prospective observational trial was conducted in an academic medical center. After institutional review board approval, 100 mechanically ventilated subjects were enrolled. A stand-alone respiratory monitor that measures IPI was placed on subjects before starting a spontaneous breathing trial and continued for up to 48 h postextubation. Clinicians were blinded, and data were recorded continuously. Extubation failure was defined as the need for positive-pressure ventilation within 48 h after extubation. Mixed-effects regression models were employed to examine differences in IPI patterns between subjects with extubation success or failure. Significant IPI changes from baseline were then evaluated to predict extubation outcome. RESULTS: IPI was successfully recorded on 62 subjects (48 successful and 14 failed extubations). Although mean IPI 5 min before and after extubation were not significantly different, mean IPI 1 h after extubation in the failure group was significantly lower by 1.19 (P = .044) compared with the successful group. Negative change in IPI 1 h after extubation increased odds of failure (odds ratio = 1.57, 95% CI 1.001–2.454). The last mean IPI recorded after extubation was also significantly lower in the failure group compared with the successful group by 3.03 (P < .001). Negative change in the last measured IPI increased odds of failure (odds ratio = 1.72, 95% CI 1.26–2.34). CONCLUSIONS: Declining IPI measurements postextubation are predictive of extubation failure. Further clinical trials are needed to assess the role of IPI in guiding interventions in extubated patients.

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.

Effect of Heliox on End-Tidal CO2 Measurement in Healthy Adults

BACKGROUND: Therapeutic gases and other modalities delivered by inhalation may affect the accuracy of capnographic measurements in 2 ways. First is the specificity of the measurement of CO2 within the device, and second is the dilution effect of supplemental gases in the ambient air during CO2 sampling by the device. Our goal was to determine if variables such as inhaled gas composition, gas flows delivered via non-rebreather mask, and mouth open or closed affect measurements of end-tidal CO2 pressure (PETCO2) measured with the Capnostream 20 capnograph. METHODS: We measured PETCO2 and breathing frequency by capnography in 20 adult normal subjects, with coaching to maintain respiratory frequency between 10 and 20 breaths/min. SpO2 was monitored to detect hypoxemia. A 6 min wash-out period occurred between each 6 min level of testing. RESULTS: A mixed models analysis revealed that the mean ± SD PETCO2 for all subjects and flows while breathing heliox (37 ± 5 mm Hg) was not different (P = .50) from the value while breathing room air (36 ± 5 mm Hg). Repeated measurements with given subjects over 6 min periods of breathing spontaneously 0 L/min, with 10 L/min, and with 15 L/min of either air or heliox showed no difference in PETCO2 related to flow: P = .97 for 0 L/min vs 10 L/min, P = .87 for 0 L/min vs 15 L/min. CONCLUSIONS: In normal subjects, PETCO2 measurements with the Capnostream 20 were not affected by heliox or gas flow at 10 or 15 L/min through a non-rebreathing mask.

Pressure control ventilation in acute lung injury

High peak inspiratory pressures during mechanical ventilation result in lung injury with hyaline membranes in many animal studies. Recent prospective, randomized studies demonstrated that lower tidal volumes and low plateau pressures decreased mortality rate and increased the number of days without ventilator use in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). As a reduction in peak airway pressures has gained more attention in the critical care literature, a closer look at pressure control ventilation (PCV) is indeed warranted. PCV is a mode of mechanical ventilation that provides a constant pressure for a preset inspiratory time (I-time). Although inspiratory flow varies to maintain the preset inspiratory pressure, it is generally delivered as a decelerating flow waveform. I-time is lengthened as necessary to improve oxygenation and gas distribution. If I-time is longer than expiratory time (E-time), the term, inverse ratio ventilation (IRV) is used to describe this method of ventilation. PCV with and without IRV has been used to treat patients with refractory hypoxemia and reduced lung compliance. PCV also may be beneficial in oxygenating and ventilating patients with air leak syndrome (bronchopleural fistula or cuff leak) and unilateral lung disease. PCV with minimal air trapping (occult positive end-expiratory pressure [PEEP]) can be used to maintain oxygen delivery, ventilation, and clinically acceptable peak airway pressures while lowering FIO2 and improving compliance in ARDS. The intent of this review is to compare theoretical benefits of PCV to other modes of ventilation, describe a method of instituting PCV that will allow for longer I-times in spontaneously breathing patients without inducing a large amount of air trapping, and discuss recent advances in PCV.

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 manufacturers 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.