Continuing Education Activity

Lung volume reduction surgery is performed for patients with end-stage chronic obstructive pulmonary disease to try and improve the quantity and quality of life. The population is growing and there have been several trials to improve patient selection for which subgroup can potentially benefit the most from lung volume reduction surgery. This activity reviews lung volume reduction surgery and highlights the role of an interprofessional healthcare team in evaluating and treating patients who undergo lung volume reduction surgery.

Objectives:

• Identify the indications of lung volume reduction surgery.
• Describe the equipment, preparation, and surgical technique in regards to lung volume reduction surgery.
• Review potential post-operative care for lung volume reduction surgery.
• Explain the importance of collaboration and communication among an interprofessional healthcare team to ensure the appropriate selection of candidates for lung volume reduction surgery and to improve postoperative care and outcomes.

Introduction

Lung volume reduction surgery (LVRS) is a surgical procedure considered for patients with chronic obstructive pulmonary disease (COPD) or severe emphysema.[1] Although first described in the 1950s, it did not gain popularity until the 1990s, due to improved surgical technology and management of complications.[2] A large, collaborative, multicenter, randomized control trial for LVRS, known as the National Emphysema Treatment Trial (NETT), was published in 2003 to assess the effectiveness of LVRS on quality of life and survival advantage compared to available medical therapy.[3] It is considered a landmark study, and the results of the comprehensive NETT study guide our current selection criteria for LVRS patients. However, long-term outcomes for LVRS, unilateral versus bilateral surgery, cost-effectiveness, and LVRS as a bridge-to-lung transplant are all areas of LVRS research that are still being explored.[4][5][6][7][8]

Anatomy and Physiology

With a rising incidence, COPD is a leading cause of mortality worldwide, and patients who have severe emphysema can have a poor quality of life with symptoms that affect functionality.[9] Emphysema results in small airway disease and reduced lung elastic recoil that predisposes to lung hyperinflation from air trapping. Some pulmonary function tests (PFT) that demonstrate this obstructive process include an increase in functional residual capacity (FRC) and a decrease in inspiratory capacity (IC).[10] Early surgical approaches were focused on altering the chest wall or diaphragm, but modern surgical interventions for emphysema include transplantation, bullectomy, and lung volume reduction surgery (LVRS).[9] The short-term and long-term analysis demonstrates that over months to years, LVRS increases respiratory muscle strength and improves respiratory mechanics in specific patient populations.[10]

Indications

The NETT, published in 2003, was a randomized control trial across 17 institutions with over 1,000 patients enrolled to determine the effect of medical therapy compared to medical therapy and LVRS. Inclusion criteria for NETT included:

• Body mass index (BMI) less than 32 kg/m2
• Forced-expiratory volume in 1 second (FEV1) of less than 45% predicted
• The arterial partial pressure of carbon dioxide (PaCO2) of less than 60 mm Hg
• The arterial partial pressure of oxygen (PaO2) of greater than 45 mm Hg
• A 6-min walk test distance of greater than 140 m
• No smoking for at least 4 months before initial screening[9]

Surgical patients in NETT had an average PaO2 of 64 (+/- 10) mm Hg and PaCO2 of 43 (+/- 6) mm Hg.[3] In the non-high-risk group, they demonstrated that heterogeneous distribution of upper lobe predominant emphysema and low baseline exercise capacity predicated decreased mortality after LVRS compared to no surgery. Low exercise capacity was defined as less than 25 Watts (W) for females and less than 40 W for males.[9]

Contraindications

In the landmark NETT trial, the cut-off for stopping the protocol was greater than an 8% 30-day mortality rate for patients enrolled in the treatment arm of the study. This included monitoring the subgroups of patients undergoing LVRS. The NETT Research Group found that, after randomization, patients with an FEV1 less than 20% predicted and either a diffusion capacity for carbon monoxide (DLCO) of less than 20% predicted or the presence of homogenous emphysema, had a 30-day mortality rate of 16% in the LVRS arm (69 patients) compared to 0% medical therapy alone arm (70 patients). Even those who survived surgery had similar quality of life and only small improvements in functional tests. This particular subgroup of LVRS patients was defined as those with:

• A low FEV1 (less than 20% predicted) AND
• A DLCO of less than 20% predicted OR
• Homogenous emphysema on computed tomography (CT) scan

This subgroup of patients was more likely to be harmed than to benefit from surgical intervention for the treatment of severe emphysema, with a higher risk for death after LVRS (high-risk group).[11]

The non-high-risk patients were then subdivided into four groups based on their disease pattern and exercise capacity. Patients in the non-high-risk subgroup with primarily non-upper lobe emphysema and low exercise capacity did not gain any increased survival with LVRS compared to medical therapy. Among patients in the non-high-risk subgroup with high exercise capacity and primarily non-upper lobe emphysema, LVRS increased mortality compared with medical therapy and did not improve exercise capacity.[9] 

Equipment

The equipment necessary for LVRS depends on the type of approach used. Typically two different surgical techniques for LVRS are used and are institution-dependent:

• Median Sternotomy
• Video-Assisted Thoracic Surgery (VATS)[9] 

Special surgical equipment such as sternal saw for median sternotomy, or insufflation/camera equipment for VATS should be prepared ahead of time. Special anesthesia considerations such as a double-lumen endotracheal tube, arterial line insertion/monitoring, and intra-operative/post-operative pain-control methods (epidural, nerve block, patient-controlled analgesia (PCA) pump, etc.) should be determined ahead of time. Although some institutions use buttressing material with their stapler to try and prevent air leaks, there has been no evidence to suggest that this decreases post-operative air leaks in LVRS patients.[12] 

Personnel

Personnel necessary for LVRS include functional operating room staff to perform thoracic surgery. This includes a thoracic surgeon, surgical assistant, operating room nurses, and anesthesiologist. Post-operative care should be performed by those experienced in taking care of post-surgical thoracic surgery patients, which usually includes pain control, chest tube management, and aggressive bowel regimen. Patients with severe emphysema are usually followed by a pulmonologist and should maintain pre-operative and post-operative follow-up.

Preparation

Prior to undergoing LVRS, patients require an extensive pre-operative workup to ensure the proper patient selection and potential maximal benefit compared to medical therapy for severe COPD. This includes imaging: a chest x-ray and a high-resolution CT scan. Laboratory workup should also be performed, including an arterial blood gas (ABG). Pulmonary function testing includes values for FEV1 and DLCO. A 6-minute walk test is standard to observe oxygen requirements and distance. This is also a baseline metric to assess improvement after rehabilitation. Patients should also have a cardiopulmonary workup, including an electrocardiogram (EKG) and a stress test if significant coronary artery disease is suspected. 

Most patients enroll in pulmonary pre-habilitation programs for several weeks to observe whether there is an improvement in functional status and exercise capacity. Patients also need to comply with smoking cessation requirements (usually greater than 6 months). Pulmonary post-operative rehabilitation programs are also recommended for patients after they undergo LVRS. 

Technique or Treatment

All patients should be under general anesthesia with endotracheal intubation. NETT did not require institutions to comply with uniform surgical approaches and included both median sternotomy (MS) or video-assisted thoracic surgery (VATS), and allowed buttressing material to try to prevent air leaks.[9] Thus, both techniques were performed and analyzed within this large randomized control trial. By surgically removing portions of the lung parenchyma (usually with a stapling device), LVRS attempts to decrease the residual volume in pulmonary function tests and to mechanically improve respiratory functionality by altering anatomic and physiologic lung mechanics.[10] When performing VATS for bilateral LVRS, the patient will need to be in lateral decubitus positioning on one side and then repositioned for the contralateral side. MS should be performed with the patient in the supine position.

According to an updated review of NETT and long-term follow-up, there was no difference in 90-day mortality or intra-operative blood loss between MS or VATS.[12] However, recovery time and hospital costs appeared to be lower with VATS (by about $10,000).[9] The decision of whether to perform one procedure or the other should be guided by institutional policy and provider comfort with the technique.

Other endobronchial techniques remain investigative, and non-open surgical techniques such as placement of endobronchial valves can be performed with a bronchoscope to try to accomplish the same goals without a surgical incision.[12]

Complications

In the NETT trial, patient cohorts were analyzed for operative mortality and cardiopulmonary morbidity. The subanalysis found that cardiopulmonary morbidity remained high at approximately 5.5%. Major pulmonary and cardiovascular complications were also relatively high, occurring in 20% to 30% of patients (out of 511) who were considered a non-high-risk subset of LVRS patients. Naunheim et al. found that patients with non-upper-lobe-predominant emphysema were one of the factors associated with increased mortality.[13]

Some other complications include:

• Air leak
• Major cardiovascular complications, including arrhythmias, myocardial infarction, or pulmonary embolus
• Hypoxia
• Infections, including pneumonia
• Major pulmonary complications including respiratory failure requiring reintubation, prolonged intubation, or tracheostomy[12][13]

Air leak is one of the most common complications following LVRS, with the NETT trial patients estimating 90% in the 30-day postoperative period. However, only 12% of patients had an air leak greater than 30 days. It was concluded that not having an air leak post-operatively was not associated with the specific surgical technique.[14]

Clinical Significance

Patients with primarily upper lobe distribution of emphysema seen on CT and low exercise capacity had improved mortality compared to medical therapy alone in the NETT trial.[3] Despite studies showing the benefits of LVRS in treating specific severe emphysema patients, it is believed that LVRS is an underutilized therapy in the United States. Based on Medicare data from 2004 - 2006, it appears that the number of LVRS procedures has remained low and stagnant.[4][12] The cost-effectiveness of LVRS and NETT demonstrated in the subgroup of patients with upper lobe emphysema and low exercise capacity also had a more favorable economic outcome compared to the relatively unfavorable cost-effectiveness of the trial overall.[7] Patients also need to be screened with imaging to determine if they are appropriate candidates for LVRS and referred to a NETT center.[9] 

In addition to becoming a surgical treatment option for emphysema patients, LVRS can also serve as an adjunct for adult and pediatric lung transplant patients pre-transplant and post-transplant.[8][15] Because of their medical complexity, taking care of end-stage chronic obstructive pulmonary disease patients post-operatively requires an interprofessional approach to achieve the best possible outcome. Research is currently underway to identify which patients benefit from an endoscopic approach to LVRS with endobronchial valves.

Enhancing Healthcare Team Outcomes

Although LVRS is considered a thoracic surgical intervention, these patients are at high risk for cardiopulmonary morbidities. There is about a 20% to 30% morbidity rate. Since the complications are multifactorial in patients who are already at risk for cardiac and pulmonary complications, a well-prepared healthcare team can improve outcomes and patient safety by becoming educated about potential complications and treatment.[13] [Level 1]

Nursing, Allied Health, and Interprofessional Team Interventions

Despite studies showing the benefits of LVRS in treating specific severe emphysema patients, it is believed that LVRS is an underutilized therapy in the U.S. Based on Medicare data from 2004 - 2006, it appears that the number of LVRS procedures has remained low and stagnant.[4][12] A retrospective analysis of 413 patients identified about 15% of emphysema patients who had upper-lobe emphysema on imaging, and should at least qualify for a pre-operative assessment of LVRS appropriateness. Education needs to occur to properly screen and identify patients that could benefit from this therapy.[9] [Level 3]

Nursing, Allied Health, and Interprofessional Team Monitoring

LVRS patients are at high risk for cardiopulmonary morbidities. There is about a 20% to 30% morbidity rate. Since the complications are multifactorial in patients who are already at risk for cardiac and pulmonary complications, a well-prepared interprofessional healthcare team can improve outcomes and patient safety through appropriate monitoring, including pulse oximetry and telemetry monitoring. Interprofessional teams need to be educated about potential complications and treatment. For example, a post-operative LVRS may require pain medication, but this may also worsen respiratory status through respiratory depressing that may be poorly tolerated.[13] [Level 1]