Breathing Pattern In Subjects Research Articles

Free-breathing radial imaging using a pilot-tone radiofrequency transmitter for detection of respiratory motion.

To describe an approach for detection of respiratory signals using a transmitted radiofrequency (RF) reference signal called Pilot-Tone (PT) and to use the PT signal for creation of motion-resolved images based on 3D stack-of-stars imaging under free-breathing conditions. This work explores the use of a reference RF signal generated by a small RF transmitter, placed outside the MR bore. The reference signal is received in parallel to the MR signal during each readout. Because the received PT amplitude is modulated by the subject's breathing pattern, a respiratory signal can be obtained by detecting the strength of the received PT signal over time. The breathing-induced PT signal modulation can then be used for reconstructing motion-resolved images from free-breathing scans. The PT approach was tested in volunteers using a radial stack-of-stars 3D gradient echo (GRE) sequence with golden-angle acquisition. Respiratory signals derived from the proposed PT method were compared to signals from a respiratory cushion sensor and k-space-center-based self-navigation under different breathing conditions. Moreover, the accuracy was assessed using a modified acquisition scheme replacing the golden-angle scheme by a zero-angle acquisition. Incorporating the PT signal into eXtra-Dimensional (XD) motion-resolved reconstruction led to improved image quality and clearer anatomical depiction of the lung and liver compared to k-space-center signal and motion-averaged reconstruction, when binned into 6, 8, and 10 motion states. PT is a novel concept for tracking respiratory motion. Its small dimension (8 cm), high sampling rate, and minimal interaction with the imaging scan offers great potential for resolving respiratory motion.

Impact of Gas Masks on the Work of Breathing and Breathing Pattern in Subjects With Stable COPD.

The gas mask constitutes the main respiratory protective equipment in a chemical, biological, radiological, or nuclear environment. The aim of the study was to evaluate the impact of the gas mask on respiratory pattern, gas exchange, and indexes of respiratory effort in patients with moderate to severe stable COPD. Crossover evaluation with 3 randomized-order, 10-min conditions: at rest and with and without a gas mask using 2 different filtered cartridges, each with a distinct inspiratory resistance (cartridge A = 3.5 cm H2O; cartridge B = 2.2 cm H2O, both at 1 L/s). The study involved 8 subjects with COPD, and breathing patterns, indexes of respiratory effort, and capillary blood gases were evaluated. Comparisons of these parameters were made between the tested conditions. Mean subject age was 69 y, and mean FEV1 = 1.3 L (47% predicted). Short-term utilization of the gas mask was associated with a significant increase in the indexes of effort in comparison to baseline without a mask. The esophageal product-time product significantly increased in comparison with baseline (cartridge A = 281 ± 65 cm H2O/s/min, cartridge B = 253 ± 47 cm H2O/s/min, and baseline = 184 ± 46 cm H2O/s/min, P < .001). There were negligible changes in the breathing pattern and gas exchange. Indexes of respiratory effort increased slightly in subjects with stable COPD while using a gas mask. This effect was likely related to increased inspiratory resistance when the mask was worn. These data are reassuring for the potential short-duration use of such protection for patients with moderate to severe COPD.

Lung Function and Breathing Pattern in Subjects Developing High Altitude Pulmonary Edema

IntroductionThe purpose of the study was to comprehensively evaluate physiologic changes associated with development of high altitude pulmonary edema (HAPE). We tested whether changes in pulmonary function and breathing pattern would herald clinically overt HAPE at an early stage.MethodsIn 18 mountaineers, spirometry, diffusing capacity, nitrogen washout, nocturnal ventilation and pulse oximetry were recorded at 490 m and during 3 days after rapid ascent to 4559 m. Findings were compared among subjects developing HAPE and those remaining well (controls).ResultsIn 8 subjects subsequently developing radiographically documented HAPE at 4559 m, median FVC declined to 82% of low altitude baseline while closing volume increased to 164% of baseline (P<0.05, both instances). In 10 controls, FVC decreased slightly (to 93% baseline, P<0.05) but significantly less than in subjects with HAPE and closing volume remained unchanged. Sniff nasal pressure was reduced in both subjects with and without subsequent HAPE. During nights at 4559 m, mean nocturnal oxygen saturation dropped to lower values while minute ventilation, the number of periodic breathing cycles and heart rate were higher (60%; 8.6 L/min; 97 cycles/h; 94 beats/min, respectively) in subjects subsequently developing HAPE than in controls (73%; 5.1 L/min; 48 cycles/h; 79 beats/min; P<0.05 vs. HAPE, all instances).ConclusionThe results comprehensively represent the pattern of physiologic alterations that precede overt HAPE. The changes in lung function are consistent with reduced lung compliance and impaired gas exchange. Pronounced nocturnal hypoxemia, ventilatory control instability and sympathetic stimulation are further signs of subsequent overt HAPE.RegistrationClinicalTrials.gov identifier: NCT00274430

Investigation of breathing maneuvers using free breathing and video biofeedback techniques during radiation therapy treatment for non small cell lung cancer patients

The goal of radiation therapy treatment increases as the breathing motion decreases, which then will lead to desirable and accurate conformal dose distributions for mobile lung cancer tumor. Twelve healthy volunteers of age ranges between 18-63 years, (5 females and 7 males) were randomly selected for the study in the breathing training methods using free breathing and video biofeedback breathing. The free breathing patterns of subjects without external intervention varied considerably. It can also be observed that the patterns of breathing for each subject were not always consistent or constant with respect to time. However, video biofeedback generally controlled the variability in the breathing amplitude. The subjects, on average, breathed deeper than normal (that is, compared with free breathing) and the video mentoring helped them to maintain constant amplitude better than the free breathing method. It is concluded that the video biofeedback appeared to be generally superior to the free breathing technique in terms of its better control over the reproducibility of the baselines, amplitudes and frequencies and might produce stable breathing patterns for patients during the radiation therapy treatments of non small cell lung cancer. Key words: Non small cell lung cancer, respiratory motions, 3D-conformal radiotherapy, intensity-modulated radiation therapy, breathing monitoring, free breathing, video biofeedback.

Relationship Between Chest Wall Motion and Diaphragmatic Excursion in Healthy Adults in Supine Position

There has been a lack of studies that have used both three-dimensional analysis and imaging tools concurrently to describe lung volume changes and breathing pattern in subjects in the supine position. The purpose of this study was to investigate the correlation between volume changes estimated by optoelectronic plethysmography (OEP) and diaphragmatic excursion (DE) measured by ultrasonography of healthy adults in the supine position. Twelve healthy male subjects (age, 25.08 +/- 6.35 years) were recruited and asked to perform tidal and deep breathing in the supine position. The volume changes during chest wall motion were quantified from OEP analysis---this was done for the upper thorax (UT), lower thorax (LT), and abdominal (AB) compartment. Lung volume was measured synchronously via the mouth piece of an electrospirometer. The right diaphragmatic movement was measured by ultrasonography. Linear regression showed that all three compartments (V UT, V LT and V AB) in the inspiratory phase were correlated highly with DE during tidal and deep breathing. However, multiple linear regression analysis showed that the VAB contributed 94-95% of the variance when performing either tidal or deep breathing. A predicted equation for diaphragmatic movement during deep breathing was DE = 0.052 + 0.294 V AB. The movement of V AB can be used as an index of DE among the normal population in the supine position. Its application in patients requires further study.

Investigating the Claims of Konstantin Buteyko, M.D., Ph.D.: The Relationship of Breath Holding Time to End Tidal CO2and Other Proposed Measures of Dysfunctional Breathing

Konstantin Buteyko, M.D., Ph.D., claimed that breath holding time (BHT) can be used to detect chronic hyperventilation and that BHT predicts alveolar CO(2) (Pa(CO(2))) according to his patented mathematical formula. The Buteyko Breathing Technique (BBT) is believed to correct chronic hyperventilation as evidenced by increased BHT. In this study, we test Buteyko's claims and explore the relationship between BHT and end-tidal carbon dioxide (ETCO(2)) as well as measures of dysfunctional breathing (DB) including the Nijmegen questionnaire, the Self Evaluation of Breathing Questionnaire, and thoracic dominant breathing pattern. Eighty-three (83) adults healthy or suspected of having dysfunctional breathing, 29 with abnormal spirometry readings, 54 with normal spirometry. BHT, performed according to BBT protocols, was measured along with ETCO(2) and other measures of DB including the Nijmegen questionnaire, and manual assessment of respiratory motion, a palpatory technique for measuring thoraco-abdominal balance during breathing. Correlations between measures of DB were made in the whole sample and also in subgroups with normal or abnormal spirometry. DB measures were compared in normal and abnormal spirometry groups. The results revealed a negative correlation between BHT and ETCO(2) (r= -0.241, p<0.05), directly opposite to Buteyko's claims. BHT was significantly shorter in people with abnormal spirometry (FEV(1) or FVC<15% below predicted), with no difference in ETCO(2) levels between the abnormal and normal spirometry groups. In the abnormal spirometry group, lower BHT was found to correlate with a thoracic dominant breathing pattern. (r= -0.408, p<0.028). Although BHT does not predict resting ETCO(2), it does correlate with breathing pattern in subjects with abnormal spirometry. It is proposed that altered breathing pattern could contribute to breathing symptoms such as dyspnea and that breathing therapies such as BBT might influence symptoms by improving the efficiency of the biomechanics of breathing.

Olfactometry in fMRI studies: odor presentation using nasal continuous positive airway pressure

We describe a method for generating and presenting olfactory stimuli in functional magnetic resonance imaging (fMRI) studies for humans. The olfactometer is based on principles of air dilution olfactometry and consists of a nasal mask and a nasal Continuous Positive Airway Pressure device, both normally used for patients suffering from obstructive sleep apnea syndrome. The system allows online monitoring and recording of the subject's breathing pattern. Switching between different olfactory conditions can easily be synchronized with the inhalation phase and be controlled by a computer. Besides, switching occurs rapidly and without any optical, acoustic, thermal, or tactile cues for the subject. As an example of implementation we present a fMRI trial of olfaction using pleasant and unpleasant odor stimuli to induce different affective states in healthy subjects. The relatively inexpensive olfactometer is reliable and permits constant odor concentrations during the inherently prolonged imaging studies.