Breathing Pattern In Patients Research Articles

Clinical validation of the signs and symptoms and the nature of the respiratory nursing diagnoses in patients under invasive mechanical ventilation*

The aims of this study were to validate the signs and symptoms of the respiratory nursing diagnoses impaired gas exchange, ineffective airway clearance and ineffective breathing pattern in patients under mechanical ventilation; to verify whether intubation time and ventilatory modalities were related factors for respiratory nursing diagnoses; to verify the occurrence of shared signs and symptoms in the diagnoses and compare them with North American Nursing Diagnosis Association's proposition and to ascertain whether respiratory nursing diagnoses occur in isolated or associated patterns. The need for mechanical ventilation is common in several patients admitted to intensive care units. Therefore, critical care nurses should identify the respiratory nursing diagnoses of high incidence. Descriptive observational study, with 177 evaluations of surgical and medical critically ill adult patients undergoing invasive mechanical ventilation. The study adopted Fehring's Modified Clinical Diagnostic Validity Model, with a suggested alteration. The critical signs and symptoms were the same as proposed by North American Nursing Diagnosis Association, when the diagnoses were separately identified, although no particular sign and symptom was found for ineffective breathing pattern. Impaired gas exchange and ineffective airway clearance were identified as having 88 (49.7%) evaluations sharing the critical signs and symptoms. Intubation time and ventilation modality were related factors for the development of ineffective airway clearance and ineffective breathing pattern. The critical signs and symptoms of impaired gas exchange were abnormal blood gases and hypoxemia. For ineffective airway clearance, they were rhonchi and decreased breath sounds. No highlights were found for ineffective breathing pattern signs and symptoms. Validation by experts has confirmed these findings. The interface between ineffective airway clearance and impaired gas exchange was confirmed by the presence of the shared critical signs and symptoms. Studies like this are relevant to clinical practice because they evaluate the adequacy of Taxonomy II for patients under mechanical ventilation in clinical practice, thus allowing for the intensive care nurses to go from one mechanical and routine practice to a critical, reflexive practice, committed to professional progress.

Nocturnal breathing in cyanotic congenital heart disease

Background Sleep disordered breathing is frequently observed in patients with cardiovascular disease. Even in the absence of heart disease, acute and chronic hypoxia have been shown to promote sleep-related periodic breathing with central apnea characterized by a repetitive reduction or lack of respiratory activity. Cyanotic congenital heart disease (CCHD) is associated with chronic hypoxia, regardless of whether an increase in pulmonary artery pressures coexists. Sleep aggravated hypoxia has been observed in many such patients, but it remains to be determined whether sleep disordered breathing is contributory. We, therefore, sought to assess sleep-related breathing pattern in patients with CCHD. Methods Adults with CCHD, resting arterial oxygen saturation < 90%, and systemic ejection fraction > 40% were prospectively enrolled in a cross-sectional study. To assess sleep and respiratory indices, subjects underwent a standardized clinical appraisal that included arterial blood gas analysis and a comprehensive sleep study with an ambulatory device. An apnea–hypopnea index (AHI) ≥ 5/h was considered to indicate sleep apnea. Results Ten adults with CCHD, aged 38 ± 11 years, completed the study. Seven patients had elevated pulmonary artery pressures, with a mean systolic pressure of 86.3 ± 18.1 mm Hg. All patients demonstrated normal sleep parameters. Oxygen saturation further declined in 5 patients during sleep. However, no associated alteration in respiratory parameters was observed and no significant arrhythmia. The mean AHI was 1.1 ± 1.0/h. No subject met the pre-defined criterion for sleep apnea. Conclusion Although further oxygen desaturation may be observed during sleep in patients with CCHD, it occurs in the absence of sleep disordered breathing.

SU-FF-J-80: Real-Time Visualization of Radiation Dose Accumulation in Lung Tumors

Purpose: The focus of this work is to develop a real-time simulation and visualization method to calculate delivered dose to a moving lung tumor and to account for changes in tumor shape and location with breathing. Methods: Lung tumors move unpredictably depending on patient breathing patterns, thereby changing tumor location. A simulation framework is being developed to predict the amount and location of radiation doses deposited in both moving lung tumors and surrounding normal lung tissues to be used for real-time display of dose. A virtual cuboid of dimension 100×100×100 cubes is created with each cube of the dimension 1×1×1 mm3. A 3D volumetric sphere representing the lung tumor is place inside the cube. The motion of the 3D sphere was modeled as linear and sinusoidal simulating lung tumor motion. A radiation treatment plan of a small lung tumor was developed in a commercial planning system (iPlan, BrainLab). Each radiation beam was extracted as a 10 cm3 to match the above described cuboid. While simulating motion, the dose from each beam was accumulated to the sphere and to the cubic phantom to summate the total dose delivered. For validation, film dosimetry was performed and compared to the model. Results: A virtual patient was developed to represent a small lung tumor. The dose on the tumor was summed to generate real-time dose to the target for each beam independently. Films taken in a sagittal and in a coronal plane in a motion phantom compared favorably to cross sections through the cuboid. Conclusions: This work presents a method of simulating and modeling lung tumors in real-time and visualizing dose accumulated to them. Future developments include real-time patient motion and patient anatomy. Conflict of Interest: This work is supported in part by a grant from Calypso medical.

SU-FF-J-49: Reducting of Motion Artifacts in Cone Beam CT Using a Patient Specific Respiratory Motion Model

Purpose: Respiratory motion degrades the quality of cone beam computed tomography (CBCT) images in the thorax and abdomen and limits its localization accuracy. We describe a method of reducing motion-induced artifacts in CBCT images in the thorax using a patient-specific model to estimate 3-dimensional respiration-induced motion. Method and Materials: The patient-specific model is derived from, and applied to, the same CBCT data, thus avoiding inconsistencies caused by changes in patient's breathing pattern when using different image sets. The CBCT scan uses a 1-minute gantry rotation while recording patient respiration with an external monitor. The projection images are sorted into 4 to 6 phase bins according to the respiratory signal. Each phase bin is reconstructed to produce a series of 3D images. Nonrigid image registration calculates a series of deformation fields that maps each 3D image to a reference image at end expiration. A principle component analysis (PCA) reduces noise and redundancy in the deformation fields. The resultant deformation fields correct each 3D image by morphing it to the reference motion state. The corrected 3D images are combined to obtain a high-resolution CBCT image. We evaluate the model by comparing CBCT images before and after motion correction, in patients receiving radiation treatment for lung cancer. Results: Motion-corrected CBCT images show less respiration-induced blurring and streaking artifacts compared to standard CBCT. Fine-detailed features in lung tumor and airways become visible, and the liver boundary is more discernable. Conclusion: Preliminary results indicate that the proposed method is a potentially useful tool for improving CBCT image quality and localization accuracy in the thorax. Repeating the process at other phase bins can yield a high quality respiration-correlated (4D) CBCT image set for evaluating respiration-induced motion.

SU‐FF‐J‐01: Characterization of the Stability of Respiration for Patients Undergoing Motion‐Adaptive Lung Tumor Radiotherapy

Purpose: Lung tumor motion is due mainly to respiration. Tumor tracking during radiotherapy requires prediction of the tumor motion to compensate system lag time. Complexity and instability of a patient's breathing will influence its predictability. We have characterized the stability and predictability of the breathing patterns of lung radiotherapy patients by analyzing the time‐dependent behavior of the autocorrelation of the patient's breathing motion. Method and Materials: Breathing motion data were obtained from the CyberKnife Synchrony @ respiratory tracking system at Georgetown University Medical Center. Nine freely breathing lung cancer patients were arbitrarily selected for this study. The patients showed a wide range of breathing behavior. Respiratory motion of the chest surface was recorded for up to sixty minutes during treatment. For each breathing history the autocorrelation coefficient versus delay time was computed in a window of 55 seconds. The decay of the average autocorrelation coefficient over time was computed at various times in the breathing signal history by moving the window. This measured the instability of the breathing pattern over time. Results: The breathing patterns of all nine patients had average autocorrelation coefficients that decayed over time, indicating the breathing was non‐stationary. The rate of decay of the autocorrelation ranged widely for the patients. The predictability of each patient's breathing, as measured in a prior analysis using signal prediction algorithms, was highly correlated with the stability of the breathing pattern, as measured by its autocorrelation. Conclusion: The autocorrelation of a patient's breathing and its decay over time can characterize breathing instability. This makes it possible to compare the results of motion prediction, control and adaptation algorithms that have been tested on a variety of breathing data.

TU‐D‐M100F‐09: Breathing Motion‐Induced Dose Delivery Error Evaluations as Applied to Tomotherapy Dose Delivery

Purpose: To develop a method for evaluating breathing motion‐induced dose delivery errors in Tomotherapy dose delivery. Methods and Materials: Dosimetric inaccuracy can result from breathing‐induced tumor motion in Tomotherapy treatment delivery. Patient breathing motion patterns were simulated using quantitative spirometry‐measured patient tidal volumes and converting the tidal volume to tumor motion by varying the ratio of tumor motion to tidal volume for 34 patients. Simulations of Tomotherapy deliveries were conducted modifying the previously published techniques by using measured beam profiles instead of step‐function fluences, and couch speeds typical of Tomotherapy treatments. Radiochromic film and our in‐house 4D phantom were used to verify the algorithm. Results: As expected, the breathing motion blurred the dose distributions, but slow drifts in the average tissue position caused detectable dose errors. The dose errors were expectedly largest with the smallest (1.0cm) field size, and could be &gt;10% for motion amplitudes comparable to the field size. As the field width increased relative to the motion amplitude, and as couch‐speed (pitch) decreased, the error also decreased, and as such these settings may be preferable for patient treatments. These slow drifts occurred over time periods that were coincident with the amount of time required for the field to pass a stationary point. Measurements agreed with the simulation. Conclusions: Previous breathing motion studies did not use real patient breathing patterns and therefore did not consider the impact of slow, relatively small drifts in those patterns. The drifts change direction during the breathing measurement, causing dose errors that are both positive and negative. While the individual dose fraction errors can be &gt;10%, they are unlikely to occur in the same place each day, so the average dose is likely to be consistent with earlier studies. Conflict of Interest: This work supported in part by a grant from Tomotherapy, Inc.

Phase and amplitude binning for 4D-CT imaging

We compare the consistency and accuracy of two image binning approaches used in 4D-CT imaging. One approach, phase binning (PB), assigns each breathing cycle 2π rad, within which the images are grouped. In amplitude binning (AB), the images are assigned bins according to the breathing signal's full amplitude. To quantitate both approaches we used a NEMA NU2-2001 IEC phantom oscillating in the axial direction and at random frequencies and amplitudes, approximately simulating a patient's breathing. 4D-CT images were obtained using a four-slice GE Lightspeed CT scanner operating in cine mode. We define consistency error as a measure of ability to correctly bin over repeated cycles in the same field of view. Average consistency error μe ± σe in PB ranged from 18% ± 20% to 30% ± 35%, while in AB the error ranged from 11% ± 14% to 20% ± 24%. In PB nearly all bins contained sphere slices. AB was more accurate, revealing empty bins where no sphere slices existed. As a proof of principle, we present examples of two non-small cell lung carcinoma patients' 4D-CT lung images binned by both approaches. While AB can lead to gaps in the coronal images, depending on the patient's breathing pattern, PB exhibits no gaps but suffers visible artifacts due to misbinning, yielding images that cover a relatively large amplitude range. AB was more consistent, though often resulted in gaps when no data existed due to patients' breathing pattern. We conclude AB is more accurate than PB. This has important consequences to treatment planning and diagnosis.

Correction of respiratory motion for IMRT using aperture adaptive technique and visual guidance: A feasibility study

Intensity-modulated radiation therapy (IMRT) utilizes nonuniform beam profile to deliver precise radiation doses to a tumor while minimizing radiation exposure to surrounding normal tissues. However, the problem of intrafraction organ motion distorts the dose distribution and leads to significant dosimetric errors. In this research, we applied an aperture adaptive technique with a visual guiding system to toggle the problem of respiratory motion. A homemade computer program showing a cyclic moving pattern was projected onto the ceiling to visually help patients adjust their respiratory patterns. Once the respiratory motion becomes regular, the leaf sequence can be synchronized with the target motion. An oscillator was employed to simulate the patient's breathing pattern. Two simple fields and one IMRT field were measured to verify the accuracy. Preliminary results showed that after appropriate training, the amplitude and duration of volunteer's breathing can be well controlled by the visual guiding system. The sharp dose gradient at the edge of the radiation fields was successfully restored. The maximum dosimetric error in the IMRT field was significantly decreased from 63% to 3%. We conclude that the aperture adaptive technique with the visual guiding system can be an inexpensive and feasible alternative without compromising delivery efficiency in clinical practice.

Speech Breathing Patterns During Tracheoesophageal Speech

Although tracheoesophageal speech (TES) uses pulmonary air to drive voice production, it was hypothesized that the speech breathing patterns of patients using TES would differ from normal speakers, as speakers compensated for the increased resistance associated with alaryngeal phonation and the effects of air loss from occasional incomplete stomal occlusion. Instrumental measurements of respiratory kinematics were used to study lung volume initiation, termination, and excursion in speech and nonspeech respiratory tasks for nine participants who used TES and nine matched controls. On the nonspeech tasks, the kinematic patterns of the TES group displayed no difference from the normal participants. On speech tasks, however, they demonstrated significantly (p <0.05) reduced lung volume excursions (LVE) in maximum sustained phonation and significantly increased LVEs in both reading and conversation. The results suggest that the TES group had less efficient use of their expiratory breath stream for maximum sustained phonation as signified by reduced LVEs. In the absence of reduced respiratory function in nonspeech tasks, this finding appears to relate to either increased phonatory resistance and/or possible stomal air loss associated with producing phonation. The results of the increased LVEs on the connected speech tasks demonstrate that patients employed active compensatory patterns of speech breathing to optimize utterance length.

Optimizing 4D cone-beam CT acquisition protocol for external beam radiotherapy

Four-dimensional cone-beam computed tomography (4D-CBCT) imaging is sensitive to parameters such as gantry rotation speed, number of gantry rotations, X-ray pulse rate, and tube current, as well as a patient's breathing pattern. The aim of this study is to optimize the image acquisition on a patient-specific basis while minimizing the scan time and the radiation dose. More than 60 sets of 4D-CBCT images, each with a temporal resolution of 10 phases, were acquired using multiple-gantry rotation and slow-gantry rotation techniques. The image quality was quantified with a relative root mean-square error (RE) and correlated with various acquisition settings; specifically, varying gantry rotation speed, varying both the rotation speed and the number of rotations, and varying both the rotation speed and tube current to keep the radiation exposure constant. These experiments were repeated for three different respiratory periods. With similar radiation dose, 4D-CBCT images acquired with low current and low rotation speed have better quality over images obtained with high current and high rotation speed. In general, a one-rotation low-speed scan is superior to a two-rotation double-speed scan, even though they provide the same number of projections. Furthermore, it is found that the image quality behaves monotonically with the relative speed as defined by the gantry rotation speed and the patient respiratory period. The RE curves established in this work can be used to predict the 4D-CBCT image quality before a scan. This allows the acquisition protocol to be optimized individually to balance the desired quality with the associated scanning time and patient radiation dose.

Expiratory Abdominal Rounding in Acute Dyspnea Suggests Congestive Heart Failure

Patients in acute respiratory distress require rapid assessment of the cause of dyspnea. We have observed that many of those patients who are in congestive heart failure (CHF) exhibit rounding of the abdominal cross-section during expiration. We sought to evaluate the diagnostic utility of this breathing pattern in dyspneic patients presenting to an emergency department. Twenty-six subjects with dyspnea due to a variety of conditions were recruited from the emergency department at Beth Israel Deaconess Medical Center. Subjects ranged in age from 21 to 94 years and 81% were female. We measured variation in the anteroposterior and transverse diameters of the rib cage and abdomen using respiratory magnetometers and determined phase of respiration with a pneumotachometer. Investigators blinded to the subjects' identities and diagnoses interpreted measurements as indicating normal respiratory movement without expiratory abdominal rounding, slight expiratory rounding, or pronounced expiratory rounding. The likely cause of dyspnea was determined from discharge diagnoses in the medical record. Expiratory rounding was observed in 12/14 subjects with CHF and 5/12 subjects without CHF (p = 0.0186), and pronounced expiratory rounding was present in 11/14 patients with CHF and 2/12 patients without CHF (p = 0.0016). Test characteristics for the association of CHF with pronounced expiratory rounding were sensitivity 79%, specificity 83%, and predictive accuracy 81%. In patients with acute respiratory distress, expiratory abdominal rounding suggests CHF as the primary cause of dyspnea; a greater degree of rounding suggests a greater likelihood of CHF. The clinical utility of this diagnostic sign remains to be determined in a prospective study.

Evaluation of an infrared camera and X-ray system using implanted fiducials in patients with lung tumors for gated radiation therapy

To report on the initial clinical use of a commercially available system to deliver gated treatment using implanted fiducials, in-room kV X-rays, and an infrared camera tracking system. ExacTrac Adaptive Gating from BrainLab is a localization system using infrared cameras and X-rays. Gating signals are the patient's breathing pattern obtained from infrared reflectors on the patient. kV X-rays of an implanted fiducial are synchronized to the breathing pattern. After localization and shift of the patient to isocenter, the breathing pattern is used to gate the radiation. Feasibility tests included localization accuracy, radiation output constancy, and dose distributions with gating. Clinical experience is reported on treatment of patients with small lung lesions. Localization accuracy of a moving target with gating was 1.7 mm. Dose constancy measurements showed insignificant change in output with gating. Improvements of dose distributions on moving targets improved with gating. Eleven patients with lung lesions were implanted with 20 mmx0.7 mm gold coil (Visicoil). The implanted fiducial was used to localize and treat the patients with gating. Treatment planning and repeat computed tomographic scans showed that the change in center of gross target volume (GTV) to implanted marker averaged 2.47 mm due in part to asymmetric tumor shrinkage. ExacTrac Adaptive Gating has been used to treat lung lesions. Initial system evaluation verified its accuracy and usability. Implanted fiducials are visible in X-rays and did not migrate.

Lung deposition of aerosolized anticancer drugs with a novel inhalation system: AKITA

12037 Background: Inhalation of anticancer drugs might be a helpful route of delivery in cancer therapy, particularly for lung tumors and metastasis in the lungs. In this experimental setup 12 different drugs (including antineoplastic drugs and immunotherapeutics) were nebulized with two different jet nebulizer systems. Aerosol particle size (MMD) and mass output were characterized. Methods: MMD was measured using a laser diffraction system (Sympatec, Clausthal-Zellerfeld, Germany). Mass output measurements were performed after CEN Standard using a Flow/volume simulator with radiolabelled (99m Tc) solution/suspension. The amount of radioactivity on the filters was detected with a scintillation counter. For aerosolization two nebulizer systems were used: Pari LC Plus with Pari compressor (PARI) and Pari LC Star with AKITA compressor (AKITA). To determine lung deposition a lung deposition model (International Commission of Radiological Protection, ICRP66, 1994) was used, taking into account: mass output, particle size and breathing pattern of patients. The AKITA guides the patient with a positive pressure through the inhalation maneuver, it is breath activated and delivers the medication only during inspiration. The PARI nebulizes continuously and the patient inhales with different individual breathing pattern. Results: MMD with PARI was found to be 4.2 ± 0.4 μm compared to 3.40 ± 0.3 μm for AKITA. After filling 2.5 ml into the nebulizers we found 1.4 ml residual volume with PARI and 1.0 ml for AKITA. The output rate was 0.15 ± 0.02 ml/min for PARI and 0.29 ± 0.03 ml/min for AKITA. Lung deposition relative to the emitted dose was determined to be 28 ± 10% for PARI and 85 ± 4% for AKITA. This is because the AKITA nebulizes only during inspiration and guides the patient through the inhalation maneuver, where as the PARI is running continuously and patients inhale with different breathing pattern. The result is that from 2.5 ml filled into the nebulizer, on average 0.3 ml will be deposited in the lungs with the PARI and 1.3 ml with the AKITA. To deposit 1 ml in the lungs with AKITA it will take 7 min, with PARI about 24 min. Conclusions: By use of modern inhalation devices with controlled inhalation lung deposition for cancer therapy can be optimized. [Table: see text]

TU‐C‐ValA‐07: Intra‐ and Inter‐Modality Registration of Four‐Dimensional (4D) Images

Purpose: 4D‐imaging techniques such as 4D‐CT/MRI/PET reveal spatial and temporal details of patient's anatomy. Here we develop a 4D‐4D registration method to utilize the 4D data acquired under different conditions or using different modalities. Method: A 4D input (model or reference) consists of a number of 3D sets of images, each representing the patient's anatomy at a phase point. When the patient's breathing pattern is repeatable, the task of 4D‐4D matching is to find the appropriate 3D dataset in the model input for each phase in reference. Instead of exhaustively searching for the best match for each phase, a search algorithm was implemented, which can simultaneously find the matches for all phases with consideration of temporal relationship between the 3D image sets in the inputs. An interpolation scheme capable of deriving an image set based on two temporally adjacent 3D‐datasets was implemented to deal with the situation where the discrete temporal points of the two inputs do not coincide. Digital phantom and patient studies were performed to illustrate the inter‐/intra‐modality 4D‐4D registration technique. Results: In the phantom study where the optimal match is known, the proposed technique was able to reproduce the “ground truth” with high spatial fidelity (&lt;1.5mm). In addition, the technique regenerated all deliberately introduced “missing” 3D images at different phase points in one of the inputs because of the temporal interpolation. In a registration of gated‐MRI and 4DCT, the technique enabled us to optimally select the corresponding CT phase. The technique was also found useful for the registration of two sets of 4DCTs acquired at different time points. In this situation, a spatial accuracy of less than 2.5mm was achieved in all three cases. Conclusions: Automated 4D‐4D registration can find the best possible spatio‐temporal match between the two 4D datasets and may have significant implication for IGRT.

SU-FF-T-205: Effects of Intra-Fraction Motion On IMRT Treatment with Segments of Few Monitor Units

Introduction: Intra‐fraction motion can affect the delivered dose distribution in radiotherapy. This is a concern in IMRT because of potential interplay between the delivered fluence pattern and the patient's breathing pattern. A widely applied approach to model organ motion is the use of a probability density function (pdf) in IMRT‐optimization. We assess if breathing compromises treatment with IMRT segments delivering only few monitor units (MU), where the delivery time of the segments will be of the order of the breathing period. Further, we assess the limitation of IMRT‐optimization based on pdfs for incorporating organ motion in treatment planning.Methods:A motor‐driven platform, which moves sinusoidally with a user‐specified amplitude and a period of 4s for tumor motion was used. The measurements were performed for motion amplitude of 4cm in 4×4cm2–10×10cm2 open fields and dose‐rate of 500MUmin−1. The MUs delivered were 8 to 183MUs, corresponding to delivery times of 1s to 22s. The measurements were repeated for ten different initial phases. Results: The delivered dose to a moving target varies with initial phase and with segment delivery time. For very long segment times the delivered dose has a 1–2% spread with the initial phase. Therefore, over 30 fractions, the average dose delivered to the moving tumor will converge to the mean dose delivered over the breathing‐period. For short delivery times, the delivered dose varies significantly with the initial phase. This is because the delivered dose becomes dependent on non‐uniform dose and penumbra effects. Conclusion: Motion can compromise an IMRT treatment if the segment delivery time (1–12s) is of the order of the breathing period and motion occurs in a region of non‐uniform dose. Since the delivered dose also depends strongly on the initial phase, for short delivery times, care is needed when modeling organ motion as a pdf in IMRT optimization.

Characterization of Breathing Patterns of Patients undergoing Respiratory-Correlated Imaging

Purpose/Objective: Respiratory-induced tumor motion limits the effectiveness of radiotherapy for thoracic lesions. To account for respiratory-induced intrafraction motion an internal target volume (ITV) that includes tumor excursion during the respiratory cycle can be defined. We currently determine ITVs in two ways: from respiratory-correlated 4DCT images and from feed-back guided breath-hold (FGBH) images taken at end-inspiration and at end-expiration. A major assumption of the FGBH approach is that inspiration and expiration breath-hold GTVs accurately represent the limits of the free-breathing (FB) GTV motion.

The role of high-frequency jet ventilation in the treatment of Cheyne–Stokes respiration in patients with chronic heart failure

Background Cheyne–Stokes respiration with central sleep apnea (CSR-CSA) is common in patients with severe cardiac failure. Various modes of positive airway pressure have been suggested as treatments.The authors hypothesized that high frequency jet ventilation (HFJV) can improve central sleep apnea in patients with chronic heart failure. Methods Eleven subjects with stable, optimally treated chronic heart failure and Cheyne–Stokes respiration were tested untreated and on four treatment nights in random order: nasal oxygen (4 L/min), continuous positive airway pressure (CPAP) (mean 9.3 cm H 2O), bilevel positive airway pressure (BiPAP)(mean 12.0/5.3 cm H 2O), or HFJV(60∼80 breaths per minute) during polysomnography (EMBLA, Flaga, Reykjavik, Iceland). Results The apnea–hypopnea index (AHI) declined from 30.9 ± 8.3/h in untreated night to 23.6 ± 6.6/h oxygen night and 18.5 ± 5.0/h CPAP, 14.3 ± 3.9/h BiPAP, and 20.1 ± 4.1/h HFJV (all P < 0.001 versus control). There was no significant difference between the AHI of HFJV and that of CPAP ( P = 0.541). Arousal index decreased from 31.4 ± 13.2/h untreated to 25.0 ± 7.1/h oxygen and 13.6 ± 4.7/h CPAP, to 13.7 ± 4.9/h BiPAP and 14.4 ± 4.7/h HFJV. HFJV had the similar effect to the other therapeutic groups in arousal index ( P > 0.05). There were large increases in slow-wave and rapid eye movement (REM) sleep with HFJV. All subjects preferred HFJV to CPAP. Conclusions One night of therapy with HFJV improved nocturnal breathing pattern and sleep quality in patients with Cheyne–Stokes respiration in chronic heart failure. HFJV therapy for sleep and breathing were the same as those during a nasal CPAP night. A long-term study of the effect of HFJV on cardiovascular function is needed.

TH-C-J-6B-09: Image-Guided Respiration-Gated Treatment

Purpose: Respiratory gating based on external surrogates may have large uncertainty due to the unstable correlation between external and internal signals. The purpose of this work is to use the image guidance techniques to improve the precision of external gating. Method and Materials: The image‐guided gating procedure developed in this work including the following key components: 1) Varian RPM system for monitoring patient's respiration, 2) breath coaching technique to produce a reproducible breathing pattern intra‐ and inter‐fractionally, 3) 4D CT simulation to acquire the accurate tumor geometric information in the gating window, 4) gated on‐board kV x‐ray imaging to align the target position in the gating window, 5) gated treatment delivery, and 6) kV or EPID fluoros for treatment verification. Results: This procedure has been applied to liver and lung patients. Here we use a liver patient with implanted fiducial seeds as an example. The patient had a peak‐to‐peak motion of 2 cm under free breathing, which was reduced to less than 5 mm when gated at 30% duty cycle. The patient's breathing pattern was greatly improved with the coaching technique. The fiducial seeds detected in the gated on‐board x‐ray images were used for patient alignment, which indicated a 5 mm systematical error and ±5 mm random error in all three directions. The treatment was verified using the EPID in cine mode and it was found that the intra‐fraction residual seed motion was about 5 mm and the inter‐fraction seed motion was within +8.3/−4.5 mm in the SI direction. Conclusion: The utilization of image guidance techniques in simulation, patient setup, and treatment verification, along with breath coaching technique, can greatly increase the precision of the gating treatment based on external surrogates. Conflict of Interest: This work was partially supported by a research grant from Varian Medical Systems, Inc..

TU-C-J-6B-03: Deformable Fusion of 4D PET Images

Purpose: PET images are useful in defining treatment targets. Removing distortion from respiratory motion in the PET images is of importance for gated or 4D radiation treatments. We developed a deformable fusion method to sum up the PET images at different phases. The motion-blurring-free PET images are obtained without the sacrifice of signal to noise ratio (SNR) or increase of scanning time. Method and Materials: A GE Discovery CT/PET scanner was interfaced with Varian's RPM breathing tracking system. 4D CT and 4D PET images were correlated according to the breathing phases. Full exhalation phase was used as the planning phase. Deformable image registrations of the 4D CT images yielded the displacement maps of the lungs relative to the planning phase. PET images at each breathing phase were then warped into the planning phase using the displacement maps. Motion-blurring-free PET images were obtained by summing the warped PET images. Results: Gated PET images at each individual phase are very noisy. The uncertainty from intensity fluctuations compromises the motion reduction by gating the scan. PET images are too fuzzy to be directly used in elastic registration. Instead, we registered the 4D CT images. With regular patient breathing patterns, 4D CT images correlate with 4D PET images. Consequently, the displacement maps from registration of the 4D CT images can be used in warping the 4D PET. Image warping removed the motion distortion in the PET images. The summed images have reduced motion blurring and the same SNR as that of non-gated PET images. Conclusion: Deformable fusion of 4D PET images reduce the motion distortion in PET image and retain the SNR without increasing data acquisition time. The resultant PET images can be used in more accurate target definition in gated or 4D radiation treatments.

Inhaled beta-agonists improve lung function but not maximal exercise capacity in cystic fibrosis

Background To investigate the effects of inhaled beta-agonists on sub-maximal and maximal exercise capacity, breathing pattern, dyspnoea, leg-discomfort and spirometry in patients with cystic fibrosis (CF). Objectives Eight patients performed two maximal incremental cycle-ergometry tests on separate days with inhaled placebo or salbutamol (600 μg) administered before each test in a randomized, double-blind, placebo-controlled crossover trial. Primary outcomes were exercise duration (Exdur) in seconds (s) and maximal oxygen uptake (VO 2max) in litres/minute (L/min). Forced expiratory volume in 1 s (FEV 1) was measured immediately pre-inhaler, post-inhaler and post-exercise. Dyspnoea and leg-discomfort were assessed post-exercise. Results Within-day FEV 1 comparisons demonstrated that the placebo test day FEV 1 improved significantly post-exercise (0.11 L, p < 0.05) and the salbutamol test day FEV 1 improved significantly post-inhaler (0.22 L, p < 0.001) and post-exercise (0.07 L, p < 0.01). Between-day FEV 1 comparisons demonstrated significant improvements in post-inhaler (0.17 L, p < 0.05) and post-exercise (0.13 L, p < 0.05) FEV 1 following salbutamol. Sub-maximal and maximal exercise showed no significant difference as shown by Exdur (547 ± 154 s vs. 529 ± 127 s) and VO 2max (1.9 ± 0.5 L/min vs. 1.9 ± 0.6 L/min). No significant change in breathing pattern, dyspnoea or leg-discomfort was detected. The study had a power of 92% to detect a 10% improvement in Exdur. Conclusions In adults with CF, salbutamol improves post-exercise FEV 1 and is safe when administered immediately before exercise but does not improve exercise capacity, exercise-induced dyspnoea or leg-discomfort.