COPD Hyperinflation

This disease is caused predominantly by noxious gases and particles from smoke of tobacco and other dangerous air pollutants that are inhaled occasionally. Irritation by these noxious chemicals and other pollutants lead to release and activation of T-lymphocytes, macrophages and neutrophils, leading to release of mediators of inflammation (Beeh, et al. , 2003) that cause imbalance in protease-antiprotease equilibrium and damage structures of the lungs. Lung parenchyma destruction and airway inflammation lead to airflow limitation. Alveolar pressure promoting flow and opposition of airway resistance are determinants of expiration via airways, and therefore, there is airflow limitation in COPD. This leads to enhanced expiratory flow. Dynamic and static hyperinflation have been described. Lung hyperinflation is a major physiological sign in COPD, and has very detrimental clinical consequences to the patients.

Increased compliance of the lungs, EFL effects, or a combination of these two may cause resting hyperinflation of the lungs. Hyperinflation may worsen when respiratory system has been stressed such as during exercise or worsening symptoms. In both COPD patients and normal persons, during the period of forced expiration, increasing alveolar pressure by contracting relevant muscles produces smaller but progressive increase in expiratory air flow to a point where the flow reaches a stationary phase (plateau). According to researchers, this phenomenal relates to intra-thoracic airways dynamic compression as volume of lungs decreases. The subsequent increased airway resistance balances the generated pressure by more effort of muscles. Expiratory flow, therefore, does not dependent on muscle effort but the elastic recoil of respiratory system determines this.

Both expiratory and inspiratory airflow resistance form the main mechanisms of respiration in COPD. Decreased EELV has benefit to inspiration such that as muscles for expiration relax, the system of respiration’s passive tendency under FRC points towards inspiration. EEFV also reduces in non-strenuous exercise in older persons, but recovers to close resting levels. But in COPD patients, where limitations in airflow is present, more units are still not able to remove the gas from the lungs as time of expiration decreases as rate of respiration increases, and hence, EEFV rises (O'Donnell, et al. , 2012) despite activity of expiratory muscles. This increases the EEFV value temporarily above the baseline value. “pressure time index”. The PTI is usually determined by the level of maximum pressure of inspiration, which decreases as volume of lings increases as maximum pressure of expiration changes oppositely.

At elevated volumes extreme effort is needed to form same pressure. Airflow limitation is an expiratory occurrence and its consequences affect inspiratory muscles and not expiratory muscles because the latter cannot afford to significantly increase airflow to empty the lungs (Puente-Maestu & Stringer, 2006). Additionally, the respiratory system volume is increased and therefore, the elastic force required for thorax displacement. Expansion of tidal volume has mechanical constraints (Nield, et al. When respiratory rates are raised, there is reduction in time of expiration, leading to worsening of dynamic hyperinflation. Cardiac dysfunction Hyperinflation of lungs and elevated effort to recruit expiratory muscles weaken venous return and lead to reduced preload of the right ventricular in these patients. Dysfunction of the left ventricular function may result due to increased elastic loads and resistive loads (Miller, et al.

This occurs in continuous exercise. In this discussion, the interventions to reduce airflow limitations will be discussed, especially the use of long acting dilators of respiratory airways such as LAMA and LABA. Many scientists have described the importance of bronchodilators in management of COPD dynamic hyperinflation. These drugs increase both FEV and FVC, and reduce EELV/TLC peak exercise, and ratio of pressure of esophageal inspiration and peak pressure of esophageal inspiration. According to research, if measurements of lung volume are done, the average response of bronchodilators improve to about 76% of hyperinflated patients who have been severely affected, and to about 62% of hyperinflated patients who have been moderately affected (Puente-Maestu & Stringer, 2006). TLC could be reduce too by bronchodilators. Another study of patients having complicated irreversible COPD after therapy with 50µg salmeterol twice daily for 2 weeks revealed reduced trans-diaphragmatic product of pressure and time, Borg scores and dynamic hyperinflation during a treadmill walk but exercise endurance did not improve (Man, et al.

These studies reveal that bronchodilator effects are more pronounced in patients with limitations in airflow compared to those without. However, some studies show that some COPD patients may not respond well to bronchodilators such that their IC or FEV1 do not show improvement (Newton, et al. Therefore, as much as most patients under LABA and LAMA show improved hyperinflation, this therapy is recommended to any patient with airflow limitations. Tiotropium, salmeterol and formoterol are mostly used as long acting dilators of bronchioles. This causes increase in intracellular cAMP, which lead to relaxation of smooth muscles and dilation of bronchial airways. Inhalation is preferred to oral drugs as the administration route for these medicines because it reduces systemic adverse effects such as tremors, tachycardia and cardiac arrhythmias (Gershon, et al.

LAMA are competitive inhibitors at muscarinic receptors. They compete with acetylcholine, agonist at these receptors, and therefore, inhibit bronchomotor tone mediated by cholinergic activation. This leads to bronchodilation. A similar study suggested that a once-per-day fixed-dose of combined indacaterol and glycopyrronium improve functions of the lungs and reduce exacerbations. This was compared to either tiotropium or glycopyrronium monotherapy and the monotherapy was less effective (Canavan, 2013). Indacaterol is a LABA, while glycopyrronium is a LAMA. Tiotropium and indacaterol are equally effective in achieving bronchodilation according to a study conducted in 2013 on 3400 patients with COPD that was severe (Macfarlane, 2013). These agents demonstrated equal improvements in health status and baseline dyspnea, and similar profiles of safety. Glycopyrrolate was approved in 2015 to treat COPD hyperinflation as an inhaler medication.

It is a LAMA that causes bronchodilation via inhibition of effects of acetylcholine on smooth muscle muscarinic receptors. It is available as a combination with LABA or as a single drug. As a combination, glycopyrrolate/indacaterol inhaler was approved for management of hyperinflation in COPD patients because is showed improved FEV1 AUC from 0 to 12 hours as compared to individual components. The combination led to improved dyspnea and reduced use of rescue medication (Mahler, et al. Similarly, aclidinium, a LAMA, was approved for COPD treatment in 2012, and showed improved lung function shown by improved FEV1. Inhaled Olodaterol was approved in 2014 as a LABA that activated beta-2 receptors on smooth muscles in the airways, increasing cAMP levels and cause bronchodilation. Long-term efficacy and safety were demonstrated with once per day dose of 5 mcg olodaterol in severely affected COPD patients (Ferguson, et al.

Research indicate that increased bronchodilator therapy use associated with worsening of COPD symptoms, and therefore, tracking use of this drugs might reveal cause of exacerbations (Vestbo, et al. Since COPD patients may not respond well to current treatment therapy, research on the different responses of the same medication to different patients is being done by scientists. Group D patients have high risk and more symptoms. This group of patients are at stage III or IV with more exacerbations and hospitalization. Their CAT is usually higher than 10 while mMRC is 2 or more (Goldcopd. org, 2016). Group B patients require LAMA or LABA because their risk is low but COPD symptoms are more. Another research where COPD patients were under treatment of hyperinflation with tiotropium 18 µg per day for 6 weeks, they showed improved VC but not FEV1, but FRC decreased while IC increased for resting hyperinflation, and exercise hyperinflation and exercise dyspnea improved (O'Donnell, et al.

These effects were seen at less than 3 hours of use and continued even at 8 hours of use of the drugs dose. The effects of tiotropium 18 µg per day for 6 weeks were also seen when another research, (Maltais, et al. , 2005) was conducted in hyperinflated COPD patients. Use of salmeterol 50 µg twice daily that was added to the daily regimen for 2 weeks in the management of hyperinflation in COPD patient was researched and the findings were that this LABA medication improved FEV1, increased IC, improved exercise hyperinflation and exercise dyspnea, and increased VT and peak oxygen uptake (O'Donnell, et al. Researchers have also shown that long-acting dilators of bronchioles are more effective than short-acting bronchiole dilators (Boni, et al. Inhaled LAMA and LABA are available in combinations to facilitate easy delivery and compliance to the patients.

Inhaled medications have minimal systemic effects because they are administered to the lungs directly without passing through the systemic circulation. In this case, the patient is safer with the medication for a long period of time without experiencing any major systemic adverse effects. Current Primary Care GP surgery setting In the primary care GP surgery where I work as a nurse practitioner, patients with COPD that exacerbate frequently are common. Application of GOLD guidelines updated in 2016 is the primary care GP setting in England, is used to assess symptoms, spirometric classification, exacerbation risk and breathlessness. It classifies patients into groups A-D. Patients in Group A have low risk but fewer symptoms, those in group B have low risk and increased symptoms, those in group C have increased risk but minimal symptoms, and finally, patients in group D have high risk more symptoms.

For proper management of COPD exacerbations, risk factors need to be eliminated completely, smoking being the leading risk factor. According to these GOLD guidelines, groups A-D need risk eliminations, physical activity, SAMA and SABA. Critically ill patients require other interventions such as oxygen therapy and LVRS that may improve their life quality. Also, education programs should be initiated to mobilize people to quit smoking and eliminate any risk factors. These programs are essential to reduce the prevalence and exacerbation of this disease among the population in England. Provision and availability of appropriate equipment and personnel are required to facilitate effective interventions for every patient. Therefore, it is a requirement for every institution, including the primary care GP setting I work at, to have the necessary facilities, resources and healthcare personnel to enhance COPD hyperinflation management and prevention in the local community.

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