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Respiratory Medicine Case Reports logoLink to Respiratory Medicine Case Reports
. 2024 Jun 21;51:102078. doi: 10.1016/j.rmcr.2024.102078

Improvement of diaphragmatic excursion in the supine position in a patient with idiopathic pleuroparenchymal fibroelastosis: A case report

Masashi Shiraishi a,, Yuji Higashimoto a, Osamu Nishiyama b, Ryo Yamazaki b, Ryuji Sugiya a, Hiroki Mizusawa a, Yu Takeda a, Masaya Noguchi a, Kengo Kanki a, Mitsuo Kuwano c, Tamotsu Kimura a, Hisako Matsumoto b
PMCID: PMC11255951  PMID: 39027817

Abstract

Idiopathic pleuroparenchymal fibroelastosis (iPPFE) is a rare form of idiopathic interstitial pneumonia. We report a case of a patient with iPPFE in whom postural changes improved diaphragmatic excursion (DE) and exercise tolerance. Chest radiography showed a greater elevation of the diaphragm at maximum expiration in the supine position than the standing position. DE measured by ultrasonography was higher in the supine position than the standing position. The findings may suggest greater diaphragm movement in the supine position, leading to successful rehabilitation and improved exercise endurance. There is no effective treatment for iPPFE; therefore, an innovative treatment strategy is warranted.

Keywords: Pulmonary rehabilitation, Respiratory muscles, Ultrasonography, X-ray, Interstitial lung disease

1. Introduction

Pleuroparenchymal fibroelastosis (PPFE) is an interstitial lung disease characterized by dense subpleural consolidation with traction bronchiectasis, architectural distortion, and upper lobe volume loss. Idiopathic PPFE (iPPFE) was included as a rare form of idiopathic interstitial pneumonia in the official American Thoracic Society/European Respiratory Society 2013 classification, and patients with this condition often complain of severe exertional dyspnea [1]. Here, we report case of a patient with iPPFE in whom postural changes improved diaphragmatic excursion (DE) and exercise tolerance.

2. Case report/case presentation

A 64-year-old woman with severe dyspnea was diagnosed with iPPFE based on the findings of bilateral upper lobe volume loss and hilar elevation with emaciation (height, 165 cm; body weight, 34.3 kg; body mass index, 12.6 kg/m2) [2]. A pulmonary function test revealed restrictive ventilatory impairment and increased residual volume (RV) (forced vital capacity [FVC], 0.71 L [%FVC, 26.0%]; forced expiratory volume in 1 second [FEV1]/FVC, 100%; total lung capacity [TLC], 3.17 L [%TLC, 74.4%]; and RV, 2.44 L [%RV, 190.6%]). Arterial blood gas analysis showed hypoxemia and hypercapnia (PaO2, 69.9 Torr and PaCO2, 57.9 Torr in room air). Pulmonary rehabilitation was initiated for the severe dyspnea, which occurred even when the patient was just sitting and talking. Of note, her dyspnea was relieved in the supine position. Therefore, she could perform lower limb exercise effectively using an ergometer in the supine position. A constant-load exercise test (75% of the peak) was performed in the seated and supine positions. The endurance time was longer, tidal volume (VT) was higher, and respiratory rate and difference between the inspiratory and expiratory tidal volumes (VTi–VTe) were lower in the supine position than in the seated position (Table 1).

Table 1.

Results of constant exercise testing in different postures.

Variable Supine posture Sitting posture
Endurance time 29:27 3:33
mBorg scale, dyspnea 5 8
mBorg scale, leg fatigue 5 5
SpO2, % 96 96
HR, bpm 90 115
Peak exercise measurements
VE, L 17.1 24.7
VT, mL 533 459
RR, times/min 35.3 53.7
Ti/Ttot, % 0.60 0.55
VTi–VTe, mL 11 34

HR = heart rate, mBorg = modified Borg, SpO2 = percutaneous oxygen saturation, Ti/Ttot = inspiratory duty cycle, RR = respiratory rate, VE = minute ventilation, VT = tidal volume, VTi–VTe = difference between inspiratory and expiratory tidal volumes, bpm = beats per minute.

Chest radiography showed bilateral upper pleural thickening and an elevation of the hilar region of the lungs caused by upper lobe volume loss (Fig. 1A). Chest computed tomography revealed pleural thickening with subpleural fibrosis concentrated in the upper lobes, without lower lobe involvement (Fig. 1E). On chest radiography, at maximum inspiration, there was no difference in the diaphragm position between the standing and supine postures (Fig. 1A and C). However, at maximum expiration, the elevation of the diaphragm was greater in the supine position than in the standing position (Fig. 1B and D), suggesting that the diaphragm moved a greater distance in the supine position than in the standing position.

Fig. 1.

Fig. 1

Radiography images obtained in the standing and supine positions.

(A) Inspiration and (B) expiration in the standing position. (C) Inspiration and (D) expiration in the supine position. (E) Chest computed tomography image.

DE was measured using ultrasonography. Excursions of the right hemidiaphragm were measured using an M-mode cursor, which was rotated and placed on the axis of the diaphragmatic displacement in the stored image, followed by measurement of the displacement during each of the rest and deep breaths [3]. The DE at tidal breathing was lower in the standing position than in the supine position (13.4 mm vs. 19.2 mm; Fig. 2A and B, respectively). During deep breathing, the distance was lower in the standing position than in the supine position (20.7 mm vs. 44.5 mm; Table 2, Fig. 2C and D, respectively). Also, the lateral position was equivalent to the supine position (Table 2). The strength of the inspiratory and expiratory muscles was stronger in the supine position than in the standing position (Table 3). This case report was approved by the Ethics Committee of the Kinki University School of Medicine (Approval No. R04-44), and consent for publication of the accompanying images was obtained from the patient.

Fig. 2.

Fig. 2

Ultrasonography images of diaphragmatic excursion.

Tidal breathing in the (A) standing position and (B) supine position. Deep breathing in the (C) standing position and (D) supine position.

Table 2.

Change in diaphragm excursion in different postures.

Standing position Supine position Lateral position (left) Lateral position (right)
Tidal breathing, mm 13.4 19.2 19.0 19.2
Deep breathing, mm 20.7 44.5 42.7 43.6

Table 3.

Inspiratory and expiratory muscle strength with standing in different postures.

Standing position Supine position
PImax, cmH2O (% predicted) 29.6 (58.7) 42.7 (84.6)
PEmax, cmH2O (% predicted) 30.6 (53.7) 40.6 (71.3)

PImax: maximum inspiratory pressure, PEmax: maximum expiratory pressure.

3. Discussion

iPPFE is a rare form of idiopathic interstitial pneumonia, and patients with iPPFE complain of severe exertional dyspnea. Moreover, the 6-min walk test result is significantly lower in these patients than in those with idiopathic pulmonary fibrosis, a representative form of idiopathic interstitial pneumonia [4]. In iPPFE, the lesion is predominantly located in the upper lung, causing the upper lobe to contract and elevate the entire lung while flattening the thorax, whereas the middle and lower lobes are hyperinflated [[5], [6], [7]]. Indeed, Ishii et al. reported that as the thoracic cage flattens, FVC decreases but RV/TLC increases [8]. Therefore, in the standing or sitting position, gravity may enhance the pulmonary hyperinflation in the middle and lower lobes. In contrast, in the supine position, the compensatory overdistension of the middle and lower lobes [7] is attenuated because of the absence of a gravitational effect. In our patient, at maximum inspiration, radiography showed no difference in the diaphragm position between the standing and supine postures, while at maximum expiration, the diaphragm was elevated to a greater extent in the supine position than in the standing position. Moreover, the endurance time was longer, VT was higher, and respiratory rate and VTi–VTe were lower in the supine position than in the sitting position. These results suggest that the diaphragm does not fully elevate in the antigravity position owing to expiratory limitation in patients with iPPFE, which may contribute to ventilatory limitation and dyspnea. On the other hand, the supine position was suggested to increase diaphragm movement and inspiratory and expiratory muscle strength, leading to successful rehabilitation and improved exercise endurance. Expiratory flow limitation during tidal breathing is a major determinant of dynamic hyperinflation and exercise limitation in patients with chronic obstructive pulmonary disease (COPD) [9].

Safavi et al.‘s study using magnetic resonance imaging (MRI) obeserved that diaphragmatic movement distance is decreased in the supine position in patients with severe COPD [10]. The comfortable posture for COPD patients is the “tripod position,” wherein the trunk is tilted forward while supporting the arms; this posture relieves dyspnea and improves lung function [[11], [12], [13], [14]]. The anterior tilt posture also improves the length–tension relationship and shape of the diaphragm and increases the output required for breathing [15]. In contrast, in PPFE patients, the feeling of shortness of breath does not improve even when they lean forward, which is thought to be because of the fact that PPFE patients experience expiratory restriction due to the effects of gravity. In other words, the posture that is considered comforting is different when comparing COPD patients, who have pulmonary hyperinflation, to PPFE patients in this case report.

Although the pathophysiology of iPPFE differs from that of COPD, expiratory limitation may be an important factor in exercise tolerance and dyspnea. Considering that ultrasonography can be repeated without radiation exposure, it is possible to evaluate the difference in diaphragmatic functions due to the postural changes between patients with PPFE and those with COPD.

iPPFE is a rare disease with no effective treatment; therefore, an innovative treatment strategy is warranted for this condition [16]. Ideally, pulmonary rehabilitation should be part of the standard treatment for iPPFE. Moreover, exercise in the supine position may be more effective possibly through an improvement in DE. Nevertheless, additional studies are necessary to confirm this observation.

4. Conclusions

We reported case of a patient with iPPFE in whom postural changes dramatically improved DE and exercise tolerance. This report may provide insights into the mechanisms of dyspnea reduction and may help identify more effective ways of rehabilitation in patients with iPPFE.

Statement of ethics

This case report was approved by the Ethics Committee of the Kinki University School of Medicine (Approval No. R04-44), and consent for publication of the accompanying images was obtained from the patient.

Funding sources

This work was supported by Grants-in-Aid for Scientific Research (21K17664).

Data availability statement

All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.

CRediT authorship contribution statement

Masashi Shiraishi: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Visualization, Writing – original draft. Yuji Higashimoto: Writing – review & editing, Conceptualization, Investigation, Methodology. Osamu Nishiyama: Data curation, Methodology, Writing – review & editing. Ryo Yamazaki: Data curation, Methodology, Validation. Ryuji Sugiya: Investigation, Methodology. Hiroki Mizusawa: Data curation, Visualization. Yu Takeda: Data curation, Validation, Visualization. Masaya Noguchi: Investigation, Methodology. Kengo Kanki: Validation, Visualization. Mitsuo Kuwano: Data curation, Investigation. Tamotsu Kimura: Validation, Writing – review & editing. Hisako Matsumoto: Conceptualization, Methodology, Supervision, Writing – review & editing.

Declaration of competing interest

No conflict.

Handling Editor: DR AC Amit Chopra

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

All data generated or analyzed during this study are included in this article. Further enquiries can be directed to the corresponding author.


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