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Respir Med Case Rep
Respir Med Case Rep
Respiratory Medicine Case Reports
2213-0071
Elsevier

S2213-0071(24)00123-0
10.1016/j.rmcr.2024.102100
102100
Case Report
Hypercapnia as an absolute exclusion criteria for bronchoscopic lung volume reduction
Burgei Jonathan W. jonathan.burgei@guthrie.org
⁎
Alsheimer Katie
Lantry Julia
Swalih Mohamed
Hehn Boyd
Robert Packer Hospital, Guthrie Clinic, Pulmonary, Critical Care Department, USA
⁎ Corresponding author. jonathan.burgei@guthrie.org
28 8 2024
2024
28 8 2024
51 10210012 2 2024
25 8 2024
25 8 2024
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Bronchoscopic lung volume reduction is a procedure that involves placement of valves into the lung to intentionally cause atelectasis to help with perfusion-ventilation matching. There are strict exclusion criteria, such as hypercapnia, that prevent patients from qualifying for the procedure based on the early trials. We present a case of a patient that became a candidate for the procedure after utilizing AVAPS after BPAP failed to lower his PCO2 to qualify for the procedure. Additionally, newer studies show that patients who are hypercapnic might benefit from the procedure to improve hypercapnia.

Keywords

Bronchoscopy
COPD
Hypercapnia
Valves
AVAPS
Interventional pulmonology
Handling Editor: DR AC Amit Chopra
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pmc1 Introduction

COPD is a prevalent disease that accounted for 6 % of global deaths in 2012 making it one of the top three causes of death worldwide [1]. One sign of end-stage COPD is the development of hypercapnia. The mechanism for the development of hypercapnia is related to the respiratory muscles. As COPD progresses, hyperinflation develops. This leads to significant respiratory muscle fatigue as a result of severe loading of the respiratory muscles to create the force to overcome the increased pressure [2]. One study found that treatment of hypercapnia with non-invasive positive pressure ventilation (NIV) showed a significant improvement in 1-year mortality (12 % in the treatment group vs 33 % in the control group) [3]. Endobronchial valves are a relatively new procedure that involves placing valves in areas of the lungs to try and reduce hyperinflation by intentionally causing atelectasis. Two groundbreaking studies, the TRANSFORM trial in 2017 and the LIBERATE trial in 2018, showed clinically meaningful benefits in patients with advanced COPD who received endobronchial valves. The benefits were seen in overall lung function, quality of life, and exercise tolerance [4,5]. To qualify for these studies, there were strict exclusion criteria. The TRANSFORM trial excluded anyone with a resting PaCO2 of 55 mmHg or more whereas the LIBERATE trial had a stricter exclusion criterion of a PaCO2 greater than 50 mmHg on room air. The exclusion of patients with hypercapnia was largely due to a 3 % risk of respiratory failure [4,5]. Due to the exclusion of hypercapnic patients in the major trials, current manufacturer patient selection guidance recommends a PaCO2 of 50 mmHg or less [6]. To our knowledge this is the first case report of a patient with hypercapnia who became a candidate for BLVR by using AVAPS to decrease his PCO2.

2 Case presentation

The patient is an 81-year-old male with a past medical history of chronic obstructive pulmonary disease (COPD), hypertension, coronary artery disease (CAD), and a body mass index (BMI) of 25 kg/m2. His COPD was treated with a LABA-LAMA inhaler and azithromycin three times weekly. He was previously on roflumilast but stopped due to cost. He was additionally on BPAP of 12/6 mmHg due to hypercapnia from his severe airway disease. He presented to the pulmonary office for evaluation for bronchoscopic lung volume reduction (BLVR). At the initial visit a room air arterial blood gas (ABG) showed a PCO2 of 55 mmHg, which is above the upper limits acceptable for the procedure. His BPAP settings were increased to 16/6 mmHg, however, he was unable to tolerate the pressure increase. His device was changed to Average Volume-Assured Pressure Support (AVAPS) with a tidal volume of 450 mL, EPAP minimum 4 mmHg, EPAP maximum 6 mmHg, pressure support minimum 5 mmHg, pressure support maximum 10 mmHg and an auto rate. He had a follow up ABG one month after wearing the new device and his PCO2 improved to 50 mmHg on a room air ABG. He was able to undergo endobronchial valve placement in the left lower lobe. At a 6-week post follow up the patient had a subjective improvement in his breathing.

3 Discussion

To our knowledge there is no randomized trial that looks at utilizing AVAPS in patients that were intolerant to the pressures required on BPAP that would help reduce their hypercapnia to a level suitable for BLVR. Our patient was not considered a candidate for BLVR due to his hypercapnia while on BPAP, however, after changing to AVAPS his PaCO2 level was lowered to an acceptable range. AVAPS is a relatively newer mode that combines characteristics of both pressure and volume control. AVAPS, compared to BPAP, has been shown to have a significant improvement in several health domains, especially in overall health, physical functioning, and overall adherence [7,8]. With the use of AVAPS, the patient was able to undergo BLVR which has been shown to not only improve many quality-of-life metrics, but also mortality [4,5,9]. Our patient on short follow up did have subjective improvement in his breathing with no symptoms of hypercapnia.

A recent study published in 2022 from Germany investigated hypercapnic patients undergoing BLVR. The study included 129 patients with severe COPD and PaCO2 of 45 mmHg or more (mean PaCO2 was 50 mmHg). The patients underwent BLVR with a follow up ABG at 3 and 6 months. There was a statistically significant improvement in PaCO2 and 40 % had normal PaCO2 values. The patients who had the greatest improvement in PaCO2 were those who had complete lobar atelectasis [10]. However, this trial did exclude 7 patients who started NIV immediately prior and 2 who started immediately after valve placement. This was to avoid any bias that the NIV, rather than the valves, lowered the PaCO2. In the two patients that initiated NIV after valve placement, one patient developed a pneumothorax post-procedure and required NIV due to worsening of hypercapnia. The other patient had NIV started 1 month after valve placement due to increasing PaCO2 levels [10].

4 Conclusion

• With our case report and the new study published from Germany, hypercapnia by itself might not be an absolute contraindication for patients who would otherwise be eligible for the procedure.

• Both NIV and endobronchial valve placement can help reduce hypercapnia and ultimately help to unload the respiratory muscles.

• A more important contraindication for treatment might be symptoms of hypercapnia or muscle wasting rather than an absolute number on the ABG10.

CRediT authorship contribution statement

Jonathan W. Burgei: Writing – review & editing, Writing – original draft, Visualization, Data curation, Conceptualization. Katie Alsheimer: Data curation. Julia Lantry: Data curation. Mohamed Swalih: Data curation. Boyd Hehn: Visualization, Data curation.

Declaration of competing interest

No conflict.
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