Effect of continuous positive airway pressure associated to exercise on the breathing pattern and heart rate variability of patients undergoing coronary artery bypass grafting surgery: a randomized controlled trial

Continuous positive airway pressure (CPAP) has been used to improve gas exchange and diaphragmatic function, among others benefits. Moreover, it can be used to increase exercise tolerance and positively influence ventilatory function and breathing pattern (BP) during exercise. However, there is no information about the long-term effects of CPAP, as an adjunct to an inpatient cardiac rehabilitation (CR) program, on BP and heart rate variability (HRV) of patients after coronary artery bypass grafting surgery (CABG). Twenty patients were allocated to receive, after randomization, standard inpatient CR without CPAP (control group - CG) or CR with CPAP between 10 to 12 cmH2O (CPAP group - CPG) associated with the exercises. Participants were assessed preoperatively and on the discharge day, in the sitting rest position. Outcome measurements included BP variables, collected by respiratory inductive plethysmography, and HRV, collected by polar precision performance. The CPG presented lower values of percent rib cage inspiratory and expiratory contributions to tidal volume (%RCi and %RCe) at discharge time, compared to CG. No statistical differences between groups were observed for HRV variables and both groups presented lower values of these indices, compared to preoperative ones. In this context, the patients who received CPAP throughout the whole rehabilitation program were discharged with a better BP, which could indicate more synchronized breathing. CPAP did not influence cardiac autonomic modulation in the long term.

Quantitative analysis of breathing patterns based on wearable systems / 生物医学工程学杂志

Breathing pattern parameters refer to the characteristic pattern parameters of respiratory movements, including the breathing amplitude and cycle, chest and abdomen contribution, coordination, etc. It is of great importance to analyze the breathing pattern parameters quantificationally when exploring the pathophysiological variations of breathing and providing instructions on pulmonary rehabilitation training. Our study provided detailed method to quantify breathing pattern parameters including respiratory rate, inspiratory time, expiratory time, inspiratory time proportion, tidal volume, chest respiratory contribution ratio, thoracoabdominal phase difference and peak inspiratory flow. We also brought in "respiratory signal quality index" to deal with the quality evaluation and quantification analysis of long-term thoracic-abdominal respiratory movement signal recorded, and proposed the way of analyzing the variance of breathing pattern parameters. On this basis, we collected chest and abdomen respiratory movement signals in 23 chronic obstructive pulmonary disease (COPD) patients and 22 normal pulmonary function subjects under spontaneous state in a 15 minute-interval using portable cardio-pulmonary monitoring system. We then quantified subjects' breathing pattern parameters and variability. The results showed great difference between the COPD patients and the controls in terms of respiratory rate, inspiratory time, expiratory time, thoracoabdominal phase difference and peak inspiratory flow. COPD patients also showed greater variance of breathing pattern parameters than the controls, and unsynchronized thoracic-abdominal movements were even observed among several patients. Therefore, the quantification and analyzing method of breathing pattern parameters based on the portable cardiopulmonary parameters monitoring system might assist the diagnosis and assessment of respiratory system diseases and hopefully provide new parameters and indexes for monitoring the physical status of patients with cardiopulmonary disease.

Analysis of asthma phenotypes in children: An update / 第二军医大学学报

Asthma is a common inflammatory disease in childhood. The interaction of genes, environment and host factors contributes to the development and progression of asthma, and the heterogeneity of asthma leads to the complexity of asthma phenotype classification. In this article, we reviewed recent analyses of asthma phenotypes in children using different criteria, including the age of onset, breathing pattern, clinical characteristics, airway inflammatory cells, risk factors, immunity and genetics, and assessed the prognosis of previous asthma phenotypes based on the above criteria, hoping to provide evidence for the treatment and prognosis of children with asthma.

Effects of breathing patterns on flow field in upper airway of an OSAHS patient during natural sleep / 医用生物力学

Objective To study the effects of different pressure boundary conditions and breathing patterns on the airflow of upper airway and related physiological status of the obstructive sleep apnea hypopnea syndrome (OSAHS) patient at sleep stage with eupnea and apnea, respectively. Methods The CT scan data of an OSAHS patient during natural sleep in supine position were acquired and used to reconstruct a three-dimensional finite element model of upper airway. Meanwhile the pressure changes in laryngeal cavity of the OSAHS patient were clinically measured and then used as the boundary conditions, and four typical breathing patterns (nasal inhaling and nasal exhaling, nasal inhaling and oral exhaling, oral inhaling and nasal exhaling, oral inhaling and oral exhaling) were considered for computational fluid simulation. Results The airflow of the OSAHS patient during sleep was an unstable, whorled and bidirectional flow, which was significantly affected by pressure boundary conditions and breathing patterns. Compared with nasal breathing, the maximum velocity of airflow by mouth breathing was increased, resulting in an increase of pressure drop in oral cavity, with was about 30% in inspiration and 100% in expiration. Conclusions It is significant to use CT data of an OSAHS patient during natural sleep for model reconstruction and the clinically measured pressure in laryngeal cavity as boundary conditions for finite element simulations, and the results will contribute to understand the characteristics of flow field in upper airway of the OSAHS patient during real natural sleep.

Pletismografia optoeletrônica: uma revisão da literatura / Optoelectronic plethysmography: a review of the literature

CONTEXTUALIZAÇÃO: A pletismografia optoeletrônica (POE) é um método inovador de mensuração indireta da ventilação pulmonar, capaz de avaliar ciclo a ciclo, de forma tridimensional e em tempo real, os volumes pulmonares absolutos e suas variações nos três compartimentos que compõem a parede torácica (caixa torácica pulmonar, caixa torácica abdominal e abdome). A POE permite mensurar variáveis do padrão respiratório, da assincronia respiratória, além da contribuição de cada compartimento da parede torácica e de cada hemitórax para o volume corrente. OBJETIVOS: Fazer uma revisão de literatura sobre os seguintes aspectos relacionados à POE: histórico, princípio de funcionamento, vantagens de utilização, propriedades psicométricas, variáveis mensuradas e método de análise do sistema, ressaltando informações sobre seu manuseio. Em uma segunda parte, abordar a aplicabilidade da pletismografia optoeletrônica em diferentes condições de saúde/situações, tais como: doença pulmonar obstrutiva crônica (DPOC; efeitos agudos do exercício, reabilitação pulmonar, exercício respiratório e transplante pulmonar), asma, pacientes em terapia intensiva, doenças neuromusculares e hemiplegia. MÉTODO: Foi realizada uma busca na base de dados MedLine, SciELO e Lilacs com o termo "optoelectronic plethysmography". Foram incluídos 43 estudos. CONCLUSÃO: Tendo por base a literatura revisada, a POE mostrou-se um instrumento de avaliação respiratória capaz de fornecer informações sobre parâmetros ventilatórios de indivíduos saudáveis e com disfunções em diferentes posições, situações e ambientes. Foram apresentados os principais resultados dos estudos em que a POE foi usada em indivíduos que apresentavam DPOC representando o maior corpo de conhecimento até o momento, assim como em alguma outra condição de saúde.

BACKGROUND: Optoelectronic plethysmography (OEP) is an innovative method of indirect measurement of pulmonary ventilation, capable of breath-by-breath, three-dimensional, real time assessment of absolute lung volumes and their variations in the three compartments of the chest wall (pulmonary rib cage, abdominal rib cage, and abdomen). OEP allows the measurement of variables of breathing pattern, breathing asynchrony, and contribution of each chest wall compartment and hemithorax to the tidal volume. OBJECTIVES: To review the literature on the following aspects related to OEP: history, operating principle, advantages, psychometric properties, variables, and method of system analysis, highlighting information about its handling. In a second part, the objective is to analyze the applicability of OEP in different health conditions/situations such as: chronic obstructive pulmonary disease (COPD; acute effects of exercise, pulmonary rehabilitation, breathing exercise, and lung transplantation), asthma, patients in intensive care, neuromuscular diseases, and stroke. METHOD: A search was performed in MedLine, SciELO and Lilacs with the term "optoelectronic plethysmography". Forty-three papers were included. CONCLUSION: Based on the literature reviewed, OEP has been shown to be an assessment tool that can provide information about ventilatory parameters in healthy subjects and subjects with various dysfunctions in different positions, situations, and settings. The main results of studies on OEP in COPD are shown, representing the largest body of knowledge to date. The results of studies on OEP in other health conditions are also shown.

ANÁLISIS Y CLASIFICACIÓN DEL PATRÓN RESPIRATORIO DE PACIENTES EN PROCESO DE RETIRADA DEL VENTILADOR MECÁNICO / ANALYSIS AND CLASSIFICATION OF THE BREATHING PATTERN IN PATIENTS ON WEANING TRIAL PROCESS

La estimación del momento óptimo de retirar la ventilación asistida de un paciente en cuidado intensivo sigue siendo fundamental en la práctica clínica. En este trabajo se estudia el patrón respiratorio a partir de la señal de flujo respiratorio de pacientes en proceso de extubación teniendo en cuenta las siguientes etapas: caracterización de la señal a partir de la identificación de los ciclos respiratorios, análisis del patrón respiratorio a partir del modelado matemático de las series, y clasificación del mismo con el objetivo de identificar patrones de pacientes con posible éxito en el proceso. Se analizaron 153 pacientes clasificados en los grupos éxito, fracaso y reintubados, de acuerdo con el resultado de la prueba de extubación de tubo en T. Se seleccionaron las series temporales de tiempo de espiración, tiempo de inspiración, duración del ciclo respiratorio e índice de respiración superficial dado que presentaron diferencias significativas en los parámetros de valor medio, orden del modelo, primer coeficiente y error final de predicción. Con ellas se obtuvo una exactitud de clasificación del 86% (sensibilidad 0,86 - especificidad 0,84) utilizando un clasificador tipo discrimante lineal. Se analizaron otros clasificadores como regresión logística y máquinas de soporte vectorial.

Estimating the optimal time to remove the ventilatory support from a patient in intensive care remains essential in clinical practice. In this work we study the breathing pattern from the respiratory flow signal in the process of weaning considering the following stages: characterization of the signal from the identification of respiratory cycles, respiratory pattern analysis from mathematical modeling of the resulting series, and classification in order to identify patterns of patients with possible success in the process. We analyzed 153 patients classified into three groups: success, failure and reintubated, according to results of T-tube test. The time series for breathing duration, inspiratory time, expiratory time, and shallow breathing index that resulted in significant differences in the mean, model order, first coefficient and final error of prediction were selected. With them we obtained a classification accuracy of 86% (sensitivity 0.84 - specificity 0.86) using a linear classifier discriminate type. Other classifications were analyzed, such as logistic regression and support vector machines.

Padrão respiratório e movimento toracoabdominal em indivíduos saudáveis: influência da idade e do sexo / Breathing pattern and thoracoabdominal motion in healthy individuals: influence of age and sex

OBJETIVO: Descrever o padrão respiratório e o movimento toracoabdominal de indivíduos saudáveis considerando a idade e o sexo. MÉTODOS: Foram estudados 104 indivíduos com idades entre 20-39, 40-59 e 60-80 anos, 41 homens e 63 mulheres, com índice de massa corporal e valores espirométricos normais. A pletismografia respiratória por indutância foi utilizada para mensurar, durante o repouso e em decúbito dorsal, as seguintes variáveis: volume corrente (Vc), frequência respiratória (f), ventilação minuto (VE), razão entre o tempo inspiratório e o tempo total do ciclo respiratório (Ti/Ttot) e fluxo inspiratório médio (Vc/Ti), deslocamento da caixa torácica ( por centoCT), relação de fase inspiratória (PhRIB), relação de fase expiratória (PhREB) e ângulo de fase (AngFase). As comparações entre as faixas etárias foram realizadas por meio da ANOVA one-way ou Kruskal-Wallis H, comparações entre os sexos foram realizadas por meio dos testes t de Student para amostras independentes ou Mann-Withney U, de acordo com a distribuição dos dados, considerando significativo p<0,05. RESULTADOS: Na comparação entre os sexos, mulheres apresentaram valores significativamente menores em relação aos homens nas variáveis Vc, VE e Ti/Ttot nas faixas etárias de 20 a 39 e de 60 a 80 anos, sem nenhuma diferença na faixa etária de 40 a 59 anos. Na comparação entre as faixas etárias, indivíduos com 60 a 80 anos apresentaram PhRIB e AngFase significativamente maiores em relação aos adultos entre 20 e 39 anos, sem diferenças significativas nas variáveis do padrão respiratório. CONCLUSÃO: Os dados encontrados sugerem influência do sexo sobre o padrão respiratório e da idade sobre o movimento toracoabdominal.

OBJECTIVE: To describe the breathing pattern and thoracoabdominal motion of healthy individuals, taking age and sex into consideration. METHODS: The study included 104 individuals aged 20 to 39, 40 to 59, and 60 to 80 years (41 males and 63 females), with normal body mass index and spirometric values. Participants were evaluated at rest in the supine position, by means of respiratory inductive plethysmography. The following variables were measured: tidal volume (Vt), respiratory frequency (f), minute ventilation (VE), inspiratory duty cycle (Ti/Ttot), mean inspiratory flow (Vt/Ti), rib cage motion ( percentRC), inspiratory phase relation (PhRIB), expiratory phase relation (PhREB), and phase angle (PhaseAng). Comparisons between the age groups were performed using one-way ANOVA or Kruskal-Wallis H, while comparisons between the sexes were performed using Student's t test or the Mann-Whitney U test, depending on the data distribution; p<0.05 was taken to be significant. RESULTS: Comparison between the sexes showed that, in the age groups 20 to 39 and 60 to 80 years, women presented significantly lower values for Vt, VE, and Ti/Ttot than men, and there was no significant difference in the age group 40 to 59 years. Comparisons between the age groups showed that participants aged 60 to 80 presented significantly greater PhRIB and PhaseAng than participants aged 20 to 39 years, without significant differences in the breathing pattern. CONCLUSION: The data suggest that breathing pattern is influenced by sex whereas thoracoabdominal motion is influenced by age.

Variabilidad del patrón respiratorio durante la carga elástica inspiratoria / Variability of breathing pattern during inspiratory elastic load

La ventilación pulmonar en humanos tiene una variabilidad respiración a respiración no lineal, compleja y caótica. El objetivo del trabajo fue: caracterizar la variabilidad del patrón respiratorio en perros (n: 8) anestesiados respirando bajo carga elástica umbral (CEU) inspiratoria (7 a 50 cm H2O). Con el flujo, presión traqueal y esofágica, se analizaron: tiempo inspiratorio (Ti), ritmo [tiempo espiratorio (Te); tiempo total (Ttot), y Ti/Ttot] e impulso central (Vt/Ti), variables relacionadas [volumen corriente (Vt) y ventilación pulmonar (Ve)]. Se determinaron: variabilidad grosera (varianzas), oscilaciones de baja frecuencia (análisis espectral) y memoria a corto plazo (análisis de autocorrelación). La CEU produjo disminución de la varianza de medias en Te, Ttot, Vt y Vt/Ti (p < 0.05). La media de las varianzas del Ti/Ttot aumentó (p < 0.005) y disminuyó para el Vt y el Vt/Ti (p < 0.05). En general, el porcentaje de oscilaciones de baja frecuencia (OB%) disminuyó (p < 0.02). Durante CEU alta, las variables de ritmo no cambiaron el porcentaje de registros con autocorrelación (AU%), pero el Vt y variables relacionadas disminuyeron los AU% (p < 0.005). Hubo correlación positiva (r: 0.955, p< 0.001) entre OB% y AU% en Vt y variables relacionadas, pero las variables de ritmo no mostraron correlación. En conclusión: La CEU indujo un patrón respiratorio más monótono. La memoria a corto plazo disminuyó en la fase inspiratoria y aumentó en la espiratoria. Estos cambios ocurrieron bajo anestesia, sugiriendo que ciertas estructuras suprapontinas pueden no ser imprescindibles para la generación de estos cambios.

In humans, lung ventilation exhibits breath-to-breath variability and dynamics that are nonlinear, complex and chaotic. Our objective was to characterize the breathing pattern variational activity in anesthetized dogs (n: 8) breathing through threshold inspiratory elastic load (7 to 50 cm H2O). Starting from flow signal and tracheal and esophageal pressures, we analyzed inspiratory time (Ti), timing (expiratory time, Te; total time, Ttot; and Ti/Ttot) and central drive (Vt/Ti) and variables related to it (tidal volume, Vt and pulmonary ventilation, Ve). We measured gross variability (variances), low frequency oscillations (spectral analysis), and short term memory (autocorrelation analysis). Loading decreased variance of the mean values of Te, Ttot, Vt and Vt/Ti (p < 0.05); the mean of variances for Ti/Ttot increased (p < 0.005) while it decreased for Vt and Vt/Ti (p < 0.05). In general, percent of data recordings with low frequency oscillations (OB%) decreased (p < 0.02). During heavy load, timing parameters percent of data recordings with autocorrelations (AU%) did not change, but Vt and its related parameters decreased their AU% (p < 0.005). There was a positive correlation (r: 0.955, p < 0.001) between the existence of low frequency oscillations and autocorrelations for Vt and its related parameters, while timing variables did not show such a correlation. In conclusion, threshold elastic load induced a monotonous respiratory pattern. The short term memory decreased during inspiratory stage while increased during expiratory stage. These changes occurred during anesthesia suggesting that certain suprapontine structures may not be obligatory to induce them.

Padrão respiratório e movimento toracoabdominal de crianças respiradoras orais / Breathing pattern and thoracoabdominal motion in mouth-breathing children

OBJETIVO: Caracterizar o padrão respiratório e o movimento toracoabdominal de crianças respiradoras orais, na faixa etária entre oito e dez anos, e compará-lo ao de seus pares respiradoras nasais. MÉTODOS: Estudo observacional realizado em laboratório universitário. O número amostral calculado com base em um estudo piloto com dez crianças em cada grupo, perfazendo um total de 20 crianças, foi de 50 para um nível de significância de 0,05 e um poder estatístico de 0,80. Participaram do estudo 26 crianças respiradoras orais e 25 respiradoras nasais. A pletismografia respiratória por indutância calibrada foi o instrumento utilizado para a análise das seguintes variáveis, entre outras: freqüência respiratória (FR), contribuição da caixa torácica para o volume corrente ( por centoCT/Vc), ângulo de fase (Angfase) e a razão entre o tempo para alcançar o pico de fluxo inspiratório e o tempo inspiratório (PifT/Ti). A saturação periférica da hemoglobia em oxigênio (SpO2) foi medida pela oximetria de pulso. A análise estatística foi realizada por meio do teste t de Student para grupos independentes e do teste U de Mann-Whitney, em função da distribuição das variáveis. RESULTADOS: No total, 4.816 ciclos respiratórios foram analisados, sendo 2.455 de respiradores orais e 2.361 de respiradores nasais, com média de 94 ciclos por criança. Não houve diferença significativa entre os grupos nas variáveis estudadas (FR=20,00±2,68 versus 20,73±2,58, p=0,169; por centoCT/Vc=39,30±11,86 versus 38,36±10,93, p=0,769; Angfase=14,53±7,97 versus 13,31±7,74, p=0,583; PifT/Ti=57,40±7,16 versus 58,35±5,99, p=0,610; SpO2=96,42±1,52 por cento versus 96,88±1,01 por cento, p=0,208; respectivamente). CONCLUSÕES: Estes resultados sugerem que as crianças respiradoras orais apresentam padrão respiratório e movimento toracoabdominal semelhantes às de respiradores nasais de mesma faixa etária.

OBJECTIVE: To characterize the breathing pattern and thoracoabdominal motion of mouth-breathing children aged between eight and ten years and to compare these characteristics with those of nose-breathing children of the same ages. METHODS: This observational study was carried out in a university laboratory. The sample size of 50 subjects was estimated based on the results of a pilot study with ten children in each group (total of 20 children) and considering a significance level of 0.05 and statistical power of 0.80. Twenty-six mouth-breathing and 25 nose-breathing children participated. Calibrated respiratory inductive plethysmography was used to analyze the following variables, among others: respiratory frequency (f), rib cage contribution towards tidal volume ( percentRC/Vt), phase angle (PhAng) and the ratio between time taken to reach peak inspiratory flow and total inspiratory time (PifT/Ti). Peripheral oxygen saturation of hemoglobin (SpO2) was measured using pulse oximetry. Statistical analysis was performed using the Student's t test for independent groups or the Mann-Whitney U test, according to the sample distribution of the variables. RESULTS: A total of 4,816 respiratory cycles were analyzed: 2,455 from mouth-breathers and 2,361 from nose-breathers, with a mean of 94 cycles per child. No statistically significant differences were observed between the groups, for the variables studied (f=20.00±2.68 versus 20.73±2.58, p=0.169; percentRC/Vt=39.30±11.86 versus 38.36±10.93, p=0.769; PhAng=14.53±7.97 versus 13.31±7.74, p=0.583; PifT/Ti=57.40±7.16 versus 58.35±5.99, p=0.610; SpO2=96.42±1.52 percent versus 96.88± 1.01 percent, p=0.208; respectively). CONCLUSIONS: These results suggest that mouth-breathing children show breathing patterns and thoracoabdominal motion that are similar to those of nose-breathing children in the same age group.

Breathing pattern and thoracoabdominal motion during exercise in chronic obstructive pulmonary disease

Subjects with chronic obstructive pulmonary disease (COPD) present breathing pattern and thoracoabdominal motion abnormalities that may contribute to exercise limitation. Twenty-two men with stable COPD (FEV1 = 42.6 ± 13.5 percent predicted; age 68 ± 8 years; mean ± SD) on usual medication and with at least 5 years of diagnosis were evaluated at rest and during an incremental cycle exercise test (10 watts/2 min). Changes in respiratory frequency, tidal volume, rib cage and abdominal motion contribution to tidal volume and the phase angle that measures the asynchrony were analyzed by inductive respiratory plethysmography at rest and during three levels of exercise (30-50, 70-80, and 100 percent maximal work load). Repeated measures ANOVA followed by pre-planned contrasts and Bonferroni corrections were used for analyses. As expected, the greater the exercise intensity the higher the tidal volume and respiratory frequency. Abdominal motion contributed to the tidal volume increase (rest: 49.82 ± 11.19 percent vs exercise: 64.15 ± 9.7 percent, 63.41 ± 10 percent, and 65.56 ± 10.2 percent, respectively, P < 0.001) as well as the asynchrony [phase angle: 11.95 ± 7.24° at rest vs 22.2 ± 15° (P = 0.002), 22.6 ± 9° (P < 0.001), and 22.7 ± 8° (P < 0.001), respectively, at the three levels of exercise]. In conclusion, the increase in ventilation during exercise in COPD patients was associated with the major motion of the abdominal compartment and with an increase in the asynchrony independent of exercise intensity. It suggests that cycling exercise is an effective way of enhancing ventilation in COPD patients.

Breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises

The objective of the present study was to evaluate breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises: diaphragmatic breathing (DB), flow-oriented (Triflo II) incentive spirometry and volume-oriented (Voldyne) incentive spirometry. Seventeen healthy subjects (12 females, 5 males) aged 23 ± 5 years (mean ± SD) were studied. Calibrated respiratory inductive plethysmography was used to measure the following variables during rest (baseline) and breathing exercises: tidal volume (Vt), respiratory frequency (f), rib cage contribution to Vt (RC/Vt), inspiratory duty cycle (Ti/Ttot), and phase angle (PhAng). Sternocleidomastoid muscle activity was assessed by surface electromyography. Statistical analysis was performed by ANOVA and Tukey or Friedman and Wilcoxon tests, with the level of significance set at P < 0.05. Comparisons between baseline and breathing exercise periods showed a significant increase of Vt and PhAng during all exercises, a significant decrease of f during DB and Voldyne, a significant increase of Ti/Ttot during Voldyne, and no significant difference in RC/Vt. Comparisons among exercises revealed higher f and sternocleidomastoid activity during Triflo II (P < 0.05) with respect to DB and Voldyne, without a significant difference in Vt, Ti/Ttot, PhAng, or RC/Vt. Exercises changed the breathing pattern and increased PhAng, a variable of thoracoabdominal asynchrony, compared to baseline. The only difference between DB and Voldyne was a significant increase of Ti/Ttot compared to baseline. Triflo II was associated with higher f values and electromyographic activity of the sternocleidomastoid. In conclusion, DB and Voldyne showed similar results while Triflo II showed disadvantages compared to the other breathing exercises.

Application of breathing pattern parameters to extraction of REM sleep information / 医疗卫生装备

Objective To extract breathing pattern parameters during sleep and get the varying law of NREM and REM sleep stages. Method A newly designed respiratory inductive plethysmography (RIP) and a polysomnography (PSG) are utilized to record whole-night-sleep data simultaneously. The breathing pattern parameters obtained by RIP are dealt with according to the results of sleep stages and sleep apnea by PSG. Then the rule found out and summarized from the experiment is applied to distinguish REM sleep. Conclusion RC/VT can be used as an effective parameter to differentiate NREM and REM sleep. Using this parameter, the results of RIP totally accord with the results of PSG.

The Changes of Breathing Pattern Observed During Maximal Exercise Testing in the Patients with Chronic Airflow Obstruction: the Correlation Between the Change of Inspiratory Duty Cycle and the Degree of Airflow Obstruction / 결핵

BACKGROUND: Normal humans meet the increased ventilatory need during exercise initially by the increase of tidal volume (TV) and later by the increase of respiratory frequency (Rf). And the inspiratory duty cycle (Ti/Ttot) is also increased more than 50% for the compensation of the decrease of respiratory cycle provoked by the increase of respiratory frequency. The patients with chronic airflow obstruction show rapid and shallow breathing pattern during exorcise because of the degreased ventilatory capacity and the increased dead space ventilation. However, the studies about the change of inspiratory duty cycle are only a few and there is no literature about the relationship between the change of inspiratory duty cycle and the degree of airflow obstruction. METHODS: The subjects were the twelve patients with chronic airflow obstruction (CAO) and ten normal people. The incremental exercise test was done. The increase of work load was 10 Win CAO group and 25 Win normal control group. The analysis of the results was done by the comparison of the parameters such as minute ventilation (VE), TV, Rf, physiologic dead space (Vd/vt), and inspiratory duty cycle between the two groups. Each parameters were compared after transformation into % control duration base that means dividing the total exercise time into five fractons and % control duration data were obtained at rest, 20%, 40%, 60%, 80%, and max. Statistical analysis was done by repeated measure ANOVA using SAS program. RESULTS: The changes of VE and TV were significantly different between two groups while the change of Rf was not significant. The decrease of Vd/vt was significantly low in CAO group. Ti/Ttot was markedly increased from 38.4+3.0% at rest to 48.6+4.5% at max in normal control group while Ti/Ttot showed little change from 40.5+2.2% at rest to 42.6+3.5% at max. And the change of inspiratory duty cycle showed highly good correlation with the degree of airflow obstruction (FEVl%). (r=0.8151, p<0.05) CONCLUSIONS: The increase of Ti/Ttot during exercise observed in normal humans is absent in the patients with CAO and the change of Ti/TtDt is well correlated with the degree of airflow obstruction.