Diffuse Lung Disease & Transplant Network
Interstitial Lung Disease Section
Delay in diagnosis of IPF: How bad is the problem?
Idiopathic pulmonary fibrosis (IPF) is a devastating disease with a poor prognosis. Antifibrotic therapies for IPF are only capable of slowing disease progression without reversing established fibrosis. As such, the therapeutic efficacy of antifibrotic therapy may be reduced in patients whose diagnosis is delayed.
Unfortunately, diagnostic delay is common in IPF. Studies demonstrate that IPF diagnosis is delayed by more than a year after symptom onset in 43% of subjects, and more than 3 years in 19% of subjects (Cosgrove GP et al. BMC Pulm Med. 2018;18[9]). Approximately one-third of patients with IPF have undergone chest CT imaging more than 3 years prior to diagnosis, and around the same proportion has seen a pulmonologist within the same time span (Mooney J, et al. Ann Am Thorac Soc. 2019;16[3]:393). A median delay to IPF diagnosis of 2.2 years was noted in patients presenting to a tertiary academic medical center and was associated with an increased risk of death independent of age, sex, and forced vital capacity (adjusted hazard ratio per doubling of delay was 1.3) (Lamas DJ et al. Am J Respir Crit Care Med. 2011;184:842).
Robust improvements are clearly required for identifying patients with IPF earlier in their disease course. The Bridging Specialties Initiative from CHEST and the Three Lakes Foundation is one resource designed to improve the timely diagnosis of ILD (ILD Clinician Toolkit available at https://www.chestnet.org/Guidelines-and-Topic-Collections/Bridging-Specialties/Timely-Diagnosis-for-ILD-Patients/Clinician-Toolkit). This, and other initiatives will hopefully reduce delays in diagnosing IPF, allowing for optimal patient care.
Adrian Shifren, MBBCh, FCCP, Member-at-Large
Saniya Khan, MD, MBBS, Member-at-Large
Robert Case Jr., MD, Pulmonary & Critical Care Fellow
Critical Care Network
Mechanical Ventilation and Airways Section
Noninvasive ventilation
Noninvasive ventilation (NIV) is a ventilation modality that supports breathing by using mechanically assisted breaths without the need for intubation or a surgical airway. NIV is divided into two main types, negative-pressure ventilation (NPV) and noninvasive positive-pressure ventilation (NIPPV).
NPV
NPV periodically generates a negative (subatmospheric) pressure on the thorax wall, reflecting the natural breathing mechanism. As this negative pressure is transmitted into the thorax, normal atmospheric pressure air outside the thorax is pulled in for inhalation. Initiated by the negative pressure generator switching off, exhalation is passive due to elastic recoil of the lung and chest wall. The iron lung was a neck-to-toe horizontal cylinder used for NPV during the polio epidemic. New NPV devices are designed to fit the thorax only, using a cuirass (a torso-covering body armor molded shell).
For years, NPV use declined as NIPPV use increased. However, during the shortage of NIPPV devices during COVID and a recent recall of certain CPAP devices, NPV use has increased. NPV is an excellent alternative for those who cannot tolerate a facial mask due to facial deformity, claustrophobia, or excessive airway secretion (Corrado A et al. European Resp J. 2002;20[1]:187).
NIPPV
NIPPV is divided into several subtypes, including continuous positive airway pressure (CPAP), bilevel positive airway pressure (BPAP or BiPAP), and average volume-assured pressure support (AVAPS or VAPS). CPAP is defined as a single pressure delivered in inhalation (Pi) and exhalation (Pe). The increased mean airway pressure provides improved oxygenation (O2) but not ventilation (CO2). BPAP uses dual pressures with Pi higher than Pe. The increased mean airway pressure provides improved O2 while the difference between Pi minus Pe increases ventilation and decreases CO2.
AVAPS is a form of BPAP where Pi varies in an automated range to achieve the ordered tidal volume. In AVAPS, the generator adjusts Pi based on the average delivered tidal volume. If the average delivered tidal volume is less than the set tidal volume, Pi gradually increases while not exceeding Pi Max. Patients notice improved comfort of AVAPS with a variable Pi vs. BPAP with a fixed Pi (Frank A et al. Chest. 2018;154[4]:1060A).
Samantha Tauscher, DO, Resident-in-Training
Herbert Patrick, MD, MSEE, FCCP , Member-at-Large
Pulmonary Vascular & Cardiovascular Disease Network
Pulmonary Vascular Disease Section
A RACE to the finish: Revisiting the role of BPA in the management of CTEPH
Pulmonary thromboendarterectomy (PTE) is the treatment of choice for patients with CTEPH (Kim NH et al. Eur Respir J. 2019;53:1801915). However, this leaves about 40% of CTEPH patients who are not operative candidates due to inaccessible distal clot burden or significant comorbidities (Pepke-Zaba J et al. Circulation 2011;124:1973). For these inoperable situations, riociguat is the only FDA-approved medical therapy (Delcroix M et al. Eur Respir J. 2021;57:2002828). Balloon pulmonary angioplasty (BPA) became a treatment option for these patients in the last 2 decades. As technique refined, BPA demonstrated improved safety data along with improved hemodynamics and increased exercise capacity (Kataoka M et al. Circ Cardiovasc Interv. 2012;5:756).
A recently published crossover study, the RACE trial, compared riociguat with BPA in treating inoperable CTEPH (Jaïs X et al. Lancet Respir Med. 2022;10[10]:961). Patients were randomly assigned to either riociguat or BPA for 26 weeks. At 26 weeks, patients with pulmonary vascular resistance (PVR) more than 4 Woods Units (WU) were crossed over to receive either BPA or riociguat therapy. At 26 weeks, the BPA arm showed a greater reduction in PVR but more complications, including lung injury and hemoptysis. After a 26-week crossover period, the reduction in PVR was similar in both arms. The complication rate in the BPA arm was lower when preceded by riociguat.
In patients with inoperable CTEPH, BPA has emerged as an attractive management option in addition to the medical therapy with riociguat. However, BPA should be performed at expert centers with experience. Further studies are needed to strengthen the role and optimal timing of BPA in management of post PTE patients with residual PH.
Samantha Pettigrew, MD, Fellow-in-Training
Janine Vintich, MD, FCCP, Member-at-Large