Thoracoscopic lung volume reduction surgery for pulmonary emphysema patients with severe hypercapnia

Targeting Hypercapnia in Chronic Lung Disease and Obesity Hypoventilation: Benefits and Challenges

Hypoventilation is a complication that is not uncommon in chronic obstructive pulmonary disease and calls for both medical treatment of the underlying disease and, frequently, noninvasive ventilation either during exacerbations requiring hospitalization or in a chronic state in the patient at home. Obesity hypoventilation syndrome by definition is associated with ventilatory failure and hypercapnia. It may or may not be accompanied by obstructive sleep apnea, which when detected becomes an additional target for positive airway pressure treatment. Intensive research has not completely resolved the best choice of treatment, and the simplest modality, continuous positive airway pressure, may still be entertained.

Is preoperative hypercapnia a justified exclusion criterion for lung volume reduction surgery?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether potential surgical candidates for lung volume reduction surgery (LVRS), who have preoperative hypercapnia, should be excluded on this basis. Using the reported search, 45 papers were found, of which 14 represented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. Of these, seven papers showed a significant (P < 0.05) improvement in postoperative forced expiratory volume in 1 second (FEV1) at up to 6 months in hypercapnic patients. There were six papers which found significant decreases in postoperative arterial carbon dioxide partial pressures (PaCO2) levels following LVRS up to 6 months. There were three papers which showed significant (P < 0.05) improvements in the 6-min walk test in hypercapnic patients following LVRS. Only two papers showed an increased operative mortality in the hypercapnic group compared to the normocapnic group, while nine papers did not find a difference in perioperative mortality. The only randomized controlled study, the landmark NETT study, excluded patients with severe hypercapnia (PaCO2 >55 mmHg and >60 mmHg) and the mean PaCO2 in the surgical and medical group were 43.3 ± 5.9 and 43.0 ± 5.8, respectively. We conclude that the evidence is not strong enough to consider hypercapnia in isolation as high risk or unsuitable for LVRS.

Endoscopic lung volume reduction coil treatment in patients with chronic hypercapnic respiratory failure: an observational study

Background:

Endoscopic lung volume reduction coil (LVRC) treatment is an option for selected patients with severe emphysema. In the advanced stages, emphysema leads to respiratory failure: hypoxemia and eventually chronic hypercapnic respiratory failure. It can be hypothesized that LVRC treatment, a procedure targeting hyperinflation and thereby reducing ventilatory workload, may be especially beneficial in patients with chronic hypercapnic respiratory failure. This study was conducted to gain first insights into the effects and the safety of LVRC treatment in patients with emphysema and chronic hypercapnic respiratory failure.

Methods:

A retrospective observational study conducted in the Department of Respiratory Medicine at the University Medical Center Hamburg-Eppendorf, Germany on all patients with chronic hypercapnic respiratory failure in whom bilateral LVRC treatment was performed between 1 April 2012 and 30 September 2015.

Results:

During the study period, bilateral LVRC treatment was performed in 10 patients with chronic hypercapnic respiratory failure. Compared with baseline, bilateral LVRC treatment led to a significant increase in mean forced expiratory volume in one second (FEV₁) from 0.5 ± 0.1 l to 0.6 ± 0.2 l (p = 0.004), a decrease in residual volume (RV) from 6.1 ± 0.9 l to 5.6 ± 1.1 l (p = 0.02) and a reduction in partial pressure of carbon dioxide in arterial blood (PaCO₂) from 53 ± 5 mmHg to 48 ± 4 mmHg (p = 0.03). One case of hemoptysis requiring readmission to hospital was the only severe adverse event.

Conclusions:

LVRC treatment was safe and effective in patients with nonsevere chronic hypercapnic respiratory failure. It led not only to an improvement in lung function but also to a significant decrease in PaCO₂.

Hypoventilation syndromes

A wide variety of mechanisms can lead to the hypoventilation associated with various medical disorders, including derangements in central ventilatory control, mechanical impediments to breathing, and abnormalities in gas exchange leading to increased dead space ventilation. The pathogenesis of hypercapnia in obesity hypoventilation syndrome remains somewhat obscure, although in many patients comorbid obstructive sleep apnea appears to play an important role. Hypoventilation in neurologic or neuromuscular disorders is primarily explained by weakness of respiratory muscles, although some central nervous system diseases may affect control of breathing. In other chest wall disorders, obstructive airways disease, and cystic fibrosis, much of the pathogenesis is explained by mechanical impediments to breathing, but an element of increased dead space ventilation also often occurs. Central alveolar hypoventilation syndrome involves a genetically determined defect in central respiratory control. Treatment in all of these disorders involves coordinated management of the primary disorder (when possible) and, increasingly, the use of noninvasive positive pressure ventilation.

Improved activities of daily living, psychological state and health-related quality of life for 12 months following lung volume reduction surgery in patients with severe emphysema

OBJECTIVE

The aim of the present study was to evaluate the effect of lung volume reduction surgery (LVRS), with an emphasis on improvement in activities of daily living (ADL), psychological state and health-related quality of life (HRQL), for 12 months in patients with severe emphysema.

METHODOLOGY

Eighteen male patients (mean age +/- SD: 65.2 +/- 6.4 years) who underwent LVRS following pulmonary rehabilitation (LVRS group) and 12 patients (67.0 +/- 8.1 years) who were medicated and underwent pulmonary rehabilitation (non-LVRS group) were studied. LVRS was performed by video-assisted thoracoscopic surgery. Serial measurements of lung function, 6-min walking distance (6MWD), ADL, HRQL and psychological state scores were performed before surgery and 3, 6, and 12 months after surgery (in the LVRS group), or on the day of discharge (in the non-LVRS group).

RESULTS

As well as an improvement in FEV(1) and 6MWD, ADL scores were significantly improved in the items of 'face washing and teeth brushing', and 'indoor walking' at 3 months after LVRS (P < 0.05). At 12 months, an improvement was still found in 'indoor walking' and 'bathing'. HRQL scores were ameliorated at 3-12 months after LVRS. In the non-LVRS group, ADL and HRQL scores failed to improve in any items during the 12 months of observation. Psychological state scores were maintained in the LVRS group and were better than those in the non-LVRS group at 12 months (P < 0.05).

CONCLUSIONS

Lung volume reduction surgery improves not only lung function and exercise performance but also ADL, HRQL and psychological state for at least 12 months.

Patient selection for lung volume reduction surgery

LVRS represents a valid surgical option for a limited number of patients who have symptomatic emphysema. The results of recent controlled studies have provided a realistic view of LVRS outcomes and yielded a validated algorithm for selection of optimal candidates for surgery. Furthermore, the NETT has provided simultaneously collected cost data that have provided a unique view of the costs and benefits of LVRS in patients who have advanced emphysema. Additional data collection will better define the long-term benefits of such surgical intervention in patients who have COPD.

Effects of lung volume reduction surgery for emphysema on oxygen cost of breathing

BACKGROUND

Patients with severe pulmonary emphysema have a greatly increased oxygen cost of breathing (O(2) cost), and this is the cause of serious malnutrition, or respiratory cachexia, in such patients.

STUDY OBJECTIVES

To clarify the effect of lung volume reduction surgery (LVRS) on respiratory function and the nutritional state of these patients through a reduction in the O(2) cost of the respiratory muscles.

DESIGN

Prospective cohort study. Setting, patients, and interventions: Twenty-three patients who underwent LVRS in Tohoku University Hospital.

MEASUREMENTS

Pulmonary function and O(2) cost were measured perioperatively by utilizing a method of continuous dead space. In addition, we calculated the proportion of oxygen consumption (O(2)) of respiratory muscles to total O(2) (%O(2)resp) from the measured energy expenditure and the predicted values.

RESULTS

FEV(1) and arterial oxygen pressure increased after surgery while lung volume and dyspnea decreased (p < 0.01), and O(2) cost was also reduced from 0.044 to 0.026 log(mL/min)/(L/min) [p < 0.001]. Moreover, the change in O(2) cost had a strong negative correlation with that of FEV(1) (r = - 0.70, p < 0.001), and a moderate positive correlation with that of the ratio of residual volume to total lung capacity (r = 0.54, p < 0.01). %O(2)resp was 23.1% at rest and 55.5% at maximal ventilation. LVRS reduced %O(2)resp at maximal ventilation to 49.0% (p < 0.05), but %O(2)resp at rest did not decrease after surgery.

CONCLUSIONS

LVRS reduces energy expenditure of respiratory muscles especially during exercise by decreasing small airway obstruction and hyperinflated lung volume. This may reverse the malnourished state in end-stage emphysema.

Lung volume reduction: where do we stand?

The concept of lung volume resection (LVR) was introduced in 1995 for the treatment of end-stage emphysema patients utilizing stapled resection through a median stenotomy approach. This article discusses this procedure and the trials that have been instituted. LVR might prove to be a viable alternative treatment modality for selected, end-stage emphysema patients in the future.