In this study, we investigated the effect of time gating threshold on the delivered dose at a organ with internal motion by respiration. Generally, the internal organs have minimum motion at exhalation during normal breathing. Therefore to compare the dose distribution time gating threshold, in this paper, was determined as the moving region of target during 1 sec at the initial position of exhalation. The irradiated fields were then delivered under three conditions; 1) non-moving target 2) existence of the moving target in the region of threshold (1sec), 3) existence of the moving target region out of threshold (1.4 sec, 2 sec). And each of conditions was described by the moving phantom system. It was compared with the dose distributions of three conditions using film dosimetry. Although the treatment time increased when the dose distributions was obtained by the internal motion to consider the TGT, it could be obtained more exact dose distribution than in the treatment field that didn't consider the internal motion. And it could be reduced the unnecessary dose at the penumbra region. When we set up 1.4 sec of threshold, to reduce the treatment time, it could not be obtained less effective dose distribution than 1 sec of threshold. Namely, although the treatment time reduce, the much dose was distributed out of the treatment region. Actually when it is treated the moving organ, it would rather measure internal motion and external motion of the moving organ than mathematical method. If it could be analyzed the correlation of the internal and external motion, the treatment scores would be improved.
Exhalation ; Film Dosimetry ; Respiration*

In this study, we evaluated feasibility of applying MTV (Metabolic Target Volume) to respiratory gated radiotherapy for more accurate treatment using various SUV (Standard Uptake Value) from PET images. We compared VOI (Volume of Interest) images from 50%, 30% and 5% SUV (standard uptake volume) from PET scan of an artificial target with GTV (Gross Tumor Volume) images defined by percentage of respiratory phase from 4D-CT scan for respiratory gated radiotherapy. It is found that the difference of VOI of 30% SUV is reduced noticeably comparing with that of 50% SUV in longitudinal direction with respect to total GTV of 4D-CT image. Difference of VOI of 30% SUV from 4D-PET image defined by respiratory phase from 25% inhalation to 25% exhalation, and GTV from 4D-CT with the same phase is shown below 0.6 cm in maximum. Thus, it is better to use 4D-PET images than conventional PET images for applying MTV to gated RT. From the result that VOI of 5% SUV from 4D-PET agrees well with reference image of 4D-CT in all direction, and the recommendation from department of nuclear medicine that 30% SUV be advised for defining tumor range, it is found that using less than 30% SUV will be more accurate and practical to apply MTV for respiratory gated radiotherapy.
Exhalation ; Inhalation ; Nuclear Medicine ; Positron-Emission Tomography

Exhalation ; Humans ; Nitric Oxide ; analysis ; Nose

During general anesthesia, removal of exhaled carbon dioxide by rebreathing appliances is provided by chemical absorption and this carbon dioxide absorption during anesthesia would at first glance seem to be a simple problem. The problem, however, is far more complicated and much attention must be given to details of rebreathing appliances. Incomplete removal of carbon dioxide in circle absorber systems, which are commonly used today must be carefully monitored to prevent hypercapnea caused by accumulation of carbon dioxide in the breathing circuits. Although circle absorbers have been developed through clinical trials anesthesiologists have no reliable indication of the end point of useful life of the absorbent. This study was undertaken to investigate the useful life of the soda lime used in two type of canisters (type A: canister of anesthesia machine. Quantiflex, USA. 12.9cmX16.6cm, tbye B: canister of anesthesia machine, International 2. U.K., 13.1cmX16.9cm). the effect of flow rate on this useful life and the relations between indicator change and the endpoint of useful life of the soda lime. The control group used a as total flow rate of fresh gases at 2.0 liters per minute and the experimental group used a total flow rate of 4.0 liters per minute. The carbon dioxide concentration of 0.1% at the canister exit was employed as the end point of useful life of the absorbent and the exit carbon dioxide concentration were monitored continuously by intra-red carbon dioxide monitor apparatus(Datex Normocap CD-102, Pinland). Also the carbon dioxide concentration in the respiratory circuit of exhaling side was examined. The results were as follows: 1) In type A, the average useful life of soda lime was 1,885 minutes in the control group and 2,514 minutes in the experimental group. In type B, the average useful life of soda lime was 1,587 minutes in the control group and 1,980 minutes in the experimental group. 2) At the end point of useful life of the absorbent the level of the color change of the indicator of the absorbent in all types was above the three-fourth height of two chambered canister. 3) At the end point, end tidal CO2 concentration was 3.5 vol% in the control group 2.88 vol% in the experimental group. The data obtained from this observation indicated that the increase of total flow rate of gas and the type A canister prolonged the useful life of soda lime and that the double chambered canister could be used safely until the color change of the indicator reached the level of three fourth the height of the canister.
Absorption ; Anesthesia ; Anesthesia, General ; Carbon Dioxide ; Exhalation ; Gases ; Respiration

Asthma ; diagnosis ; Exhalation ; Humans ; Nitric Oxide ; metabolism ; Respiratory Function Tests

Breath Tests ; Child, Preschool ; Exhalation ; Humans ; Nitric Oxide ; analysis

PURPOSE: Few studies have compared fractional exhaled nitric oxide (FeNO) measurement by NIOX VERO® (NOV) and other devices in children. Moreover, there is no agreement between differences in FeNO values obtained using different devices in adults. Here, we compared FeNO values obtained using NOV and NObreath® (NOB) systems to derive a correction equation for children. METHODS: Eighty-eight participants (age 7–15 years) who were diagnosed with atopic bronchial asthma and visited Sagamihara National Hospital as outpatients between January and April of 2017 were included. We measured FeNO values obtained using NOB and NOV, and analyzed them using Wilcoxon tests and Altman-Bland plots. RESULTS: The median age of the participants was 11.5 years, and the scored Asthma Control Test (ACT) or Childhood ACT (C-ACT) was 25 (interquartile range, 24–25) or 26 (24–27). NOB and NOV values were significantly different (31 [14–52] versus 36 [20–59] ppb; P = 0.020) and strongly correlated (r = 0.92). An equation to convert NOB values into NOV values was derived using linear regression as follows: log NOV = 0.7329 × log NOB + 0.4704; NOB for 20, 40, 58, 80 and 100 ppb corresponded to NOV for 27, 44, 59, 73 and 86 ppb. Thus, NOB < 58 ppb suggested NOB < NOV, whereas NOB > 58 ppb suggested NOB > NOV. CONCLUSIONS: NOB and NOV values were strongly correlated. Participants whose FeNO values were relatively low represented NOB < NOV, whereas those whose FeNO values were relatively high represented NOB > NOV.
Adult ; Asthma ; Child* ; Exhalation ; Humans ; Linear Models ; Nitric Oxide* ; Outpatients

BACKGROUND/AIMS: Complete endotracheal tube obstruction is a medical emergency, and partial occlusion causes increased breathing rates and failure to wean off mechanical ventilation. Partial occlusion may be underestimated due to the lack of proper detection methods. We tested whether the sound of an endotracheal tube could be used to detect an endotracheal tube obstruction using an in vitro model. METHODS: An endotracheal tube was connected to a ventilator on one end and a test lung on the other. Sounds were recorded with a microphone located inside the endotracheal tube via a connector. During mechanical ventilation, we changed the endotracheal tube internal diameter from 5.0 to 8.0 mm and different grades of obstruction at different sites were used along the tube. Sound energy was compared among the different conditions. RESULTS: The energy of endotracheal tube sounds was positively correlated with the internal diameter and negatively correlated with the degree of obstruction. The rate of decline in energy differed with obstruction location. When the obstruction was more distal, the rate of decline in endotracheal sound energy was more rapid. CONCLUSIONS: Changes in the sound of an endotracheal tube can be used to detect an obstruction. Further studies are needed for clinical application.
*Airway Obstruction ; Confidence Intervals ; Exhalation ; Humans ; *Intubation, Intratracheal ; Models, Theoretical ; Positive-Pressure Respiration ; Statistics as Topic

BACKGROUND: The most important route for elimination of inhalation anesthetics is exhalation. The lower anesthetic circuit volume and absorption by the anesthetic circuit maKes recovery more fast. The purpose of this study is to evaluate the effect of the elimination of CO2 absorption canisters on the rate of recovery from anesthesia. METHODS: Forty patients were randomly assigned into two groups. Group 1 patients recovered from enflurane anesthesia with CO2 absorption canisters (baralyme), but group 2 patients emerged from anesthesia without CO2 absorption canisters. The changes of expiratory enflurane and inspiratory nitrous oxide concentration at 30, 60, 90, 120, 150, 180 sec after the end of anesthetic administration, and time from the end of anesthetic administration to extubation were measured and compared between the groups. RESULTS: Enflurane and nitrous oxide concentrations after the end of anesthetic administration in group 2 were significantly lower than in group 1 at each time interval (P < 0.05). Time from the end of anesthetic administration to extubation in group 2, 7.7 +/- 1.4 min, was significantly shorter than in group 1, 10.5 +/- 2.6 min (P < 0.05). CONCLUSIONS: The results show that the patients emerging from anesthesia without CO2 absorption canisters can recover from anesthesia more rapidly than those with CO2 absorption canisters.
Absorption* ; Anesthesia ; Anesthesia, General* ; Anesthetics, Inhalation ; Enflurane ; Exhalation ; Humans ; Nitrous Oxide

BACKGROUND: The measurement of carbon monoxide concentration in expired air is used as an objective method to analyze the smoking status. This method has been proven to be reliable and is used throughout the world but it has been only recently accepted in Korea. Therefore the purpose of this study was to examine if measuring the concentration in expired air accurately reflects the Korean's smoking status. METHODS: The subjects were from ages of 19 through 75 healthy people including smokers and nonsmokers. The smokers had their carbon monoxide measured after answering a questionnaire. This questionnaire was formed to obtain information concerning smoking status, smoking habit and factors that influence carbon monoxide measurement. Micro II smokerlyzer (Bedfont Instruments Ltd., England) was used to analyze CO concentration in expired air. The method used for measuring CO concentration was to deeply inhale and hold one's breath for 15 seconds and measure CO concentration while exhaling. RESULTS: The total number of subjects was 148(143 males, 5 females) consisting of 114 smokers, 34 non smokers(never smokers 23, ex smokers 11). The average CO concentration in exhaled air in smokers was 17.247.30 ppm, in nonsmokers 6.031.06 ppm(in ex smokers 6.361.29 ppm, in never smokers 5.870.92 ppm). A significant difference was evident between smokers and non smokers(P<0.0001). The CO concentration values compared among the groups divided in terms of daily smoking rate were as the following 11.885.57 ppm in subjects smoking less than 10 cigarettes/day, 17.356.48 ppm in those smoking 11 20 cigarettes/day, 20.006.35 ppm in the 21 30 cigarettes/day group, and 24.889.70 ppm in the 31 cigarettes/day group (p<0.0001). In addition, the CO concentration was influenced by the change of the degree of inhalation and the elapsed time since last smoking. CONCLUSION: The measurement of CO concentration in exhaled air among the Koreans proved to be an accurate and reliable method reflecting the present smoking status.
Carbon Monoxide* ; Carbon* ; Exhalation ; Humans ; Inhalation ; Korea ; Male ; Smoke* ; Smoking* ; Surveys and Questionnaires