Optoelectronic Vital Capacity Measurement for Restrictive Diseases

Depth-Based Measurement of Respiratory Volumes: A Review

Depth-based plethysmography (DPG) for the measurement of respiratory parameters is a mobile and cost-effective alternative to spirometry and body plethysmography. In addition, natural breathing can be measured without a mouthpiece, and breathing mechanics can be visualized. This paper aims at showing further improvements for DPG by analyzing recent developments regarding the individual components of a DPG measurement. Starting from the advantages and application scenarios, measurement scenarios and recording devices, selection algorithms and location of a region of interest (ROI) on the upper body, signal processing steps, models for error minimization with a reference measurement device, and final evaluation procedures are presented and discussed. It is shown that ROI selection has an impact on signal quality. Adaptive methods and dynamic referencing of body points to select the ROI can allow more accurate placement and thus lead to better signal quality. Multiple different ROIs can be used to assess breathing mechanics and distinguish patient groups. Signal acquisition can be performed quickly using arithmetic calculations and is not inferior to complex 3D reconstruction algorithms. It is shown that linear models provide a good approximation of the signal. However, further dependencies, such as personal characteristics, may lead to non-linear models in the future. Finally, it is pointed out to focus developments with respect to single-camera systems and to focus on independence from an individual calibration in the evaluation.

Chest Wall Kinematics Using Triangular Cosserat Point Elements in Healthy and Neuromuscular Subjects

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ([Formula: see text]) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with [Formula: see text] by computing the phase angles [Formula: see text] (for SB) and the correlation r (for VC) between them. Analysis of [Formula: see text] and r of the outward translation parameter [Formula: see text] of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities.

Validity of thoracic respiratory inductive plethysmography in high body mass index subjects

We aim to evaluate thoracic respiratory inductive plethysmography (RIP) in high body mass index (BMI) subjects with a pneumotachometer (PT) as a reference. We simultaneously evaluated spontaneous breathing by RIP and PT in 10 low and 10 high BMI subjects at rest and in moderate exercise. We then recorded RIP amplitude with different excursions mimicking respiratory thoracic deformation, with different sizes of RIP belts surrounding cylinders of different perimeters with or without deformable foam simulating adipose tissue. RIP responses correlated with PT values in low and high BMI groups for inspiratory time (r=0.86 and r=0.91, respectively), expiratory time (r=0.96 and r=0.91, respectively) and amplitude (r=0.82 for both) but with a bias (-0.23±0.25L) for high BMI subjects. ANOVA revealed the effects of perimeter and simulated adiposity (p<0.001 for both). We concluded that thoracic perimeter and deformity of adipose tissue are responsible for biases in RIP response in high BMI subjects.

A Cross-sectional Study of Chest Kinematics and VO2 in Children With Adolescent Idiopathic Scoliosis During Steady-state Walking

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The aim of this study was to identify the differences in oxygen consumption in children with adolescent idiopathic scoliosis (AIS) and age-matched control subjects using traditional methods and chest kinematics.

SUMMARY OF BACKGROUND DATA

AIS is a disorder affecting 2 to 3% of children between the ages of 10 and 16 and accounts for up to 85% of all scoliosis cases. The spinal deformities and subsequent rib conformational changes associated with AIS can have a significant deleterious effect on the oxygen consumption for children with mild to severe scoliosis. Previous studies found that the oxygen consumption in children with AIS was significantly more than that of peers and during walking require more energy than typically developing children.

METHODS

Thirty children (four male, 26 female), 11.7 to 18.7 years of age, were enrolled: 15 adolescent children diagnosed with mild to moderate AIS (mean cobb angle 36.2 degrees) and 15 matched adolescents. Oxygen consumption during steady-state treadmill walking was measured using a traditional methods and simultaneous kinematic analysis of the chest wall.

RESULTS

There were no significant differences in the volume of oxygen consumed in any of the phases of treadmill walking (resting, exercise, and recovery) or in breath per minute ventilation and tidal volume between control subjects and children with scoliosis (P > 0.05). Significant differences were found between assessment methods, with the kinematic analysis overestimating the average tidal volume while walking (P < 0.05).

CONCLUSION

Children with mild to moderate AIS and typically developing children do not demonstrate oxygen consumption differences when walking at a steady state on a treadmill. However, kinematic analysis of the chest wall tends to overestimate the tidal volume when walking. An offset equation is required for some variables when using kinematic data to assess oxygen consumption in children who would otherwise not comply with traditional oxygen consumption testing.

LEVEL OF EVIDENCE

3.

A Prospective Comparison of Pulmonary Function Using Traditional and Kinematic Measures in Children With and Without Adolescent Idiopathic Scoliosis

PURPOSE

Traditional pulmonary function testing can be difficult for both the subject and the test administrator and are dependent on the subject's effort and ability to follow directions. An alternative to traditional pulmonary function testing is the kinematic analysis of the chest wall. Kinematic analysis is a reliable and accurate method to evaluate pulmonary function testing that does not have the restrictions of traditional methods. It is the purpose of this study to present a new model for measuring chest motion during pulmonary function testing of children with adolescent idiopathic scoliosis (AIS) and able-bodied children.

PROCEDURES

Traditional pulmonary function testing and kinematic assessment of the chest wall was measured simultaneously during a flow volume loop and maximum voluntary ventilation test. Fifteen children with AIS and 15 able-bodied children were measured. Differences between the two groups (AIS and able-bodied) and the two testing methods (traditional and kinematic testing) were analyzed. Correlations for the two testing methods and interclass coefficients for the kinematic analysis were measured.

FINDINGS

There were no significant differences between the control group and the scoliosis group when comparing data from traditional and kinematic assessments. When comparing the differences between the traditional and kinematic data collection methods, there were significant differences for the flow volume loop and maximum voluntary ventilation. For all significant parameters, the kinematic analysis demonstrated higher values. Moderate to high Pearson correlations were found between collection methods, and high to moderate interclass correlation coefficient values were found for the kinematic analysis of the chest wall.

PRINCIPAL CONCLUSIONS

Kinematics of the chest wall can be used as a valuable resource in the future when measuring pulmonary function when a traditional method is not a viable option.

The value of respiratory muscle testing in children with neuromuscular disease

Routine lung function and respiratory muscle testing are recommended in children with neuromuscular disease (NMD), but these tests are based on noninvasive volitional maneuvers, such as the measurement of lung volumes and maximal static pressures, that young children may not always be able to perform. The realization of simple natural maneuvers such as a sniff or a cough, and the measurement of esophageal and gastric pressures during spontaneous breathing can add valuable information about the strength and endurance of the respiratory muscles in young children. Monitoring respiratory muscles in children with NMD may improve understanding of the natural history of NMD and the evaluation of disease severity. It may assist and guide clinical management and it may help the identification and selection of optimal end points, as well as the most informative parameters and patients for clinical trials.