Effect of BiPAP ventilation on respiratory physiology in patients with stable COPD / 中华健康管理学杂志

Objective:To observe the physiological effect of bi-level positive airway pressure (BiPAP) ventilation among stable chronic obstructive pulmonary disease (COPD) patients.Methods:This was a small sample size, exploratory, interventional study. A total of 10 outpatients with stable COPD were included from Department of Pulmonary and Critical Care Medicine of Zhujiang Hospital, Southern Medical University between January 2018 and December 2018. The BiPAP mode of noninvasive mechanical ventilation was adopted. The inspiratory positive airway pressure was gradually increased from 10 cmH 2O (1 cmH 2O=0.098 kPa) to 24 cmH 2O, and each time by 2 cmH 2O. The expiratory positive airway pressure remained unchanged at 4 cmH 2O. Baseline and test data were collected before and during the ventilation for comparison, including total respiratory cycle time (T tot), inspiratory time (T i), inspiratory time (T e), inspiratory tidal volume (V Ti); mouth pressure (P mo), esophageal pressure (P eso), transdiaphragmatic pressure (P di), esophageal pressure time product (PTP es), diaphragm pressure time product (PTP di), root mean square of electromyography of diaphragm (RMS), V e/RMS, inspiratory capacity (IC), the change in end-expiratory lung volume (ΔEELV) and dynamic PEEPi (PEEPi dyn). Results:All the 10 patients completed the trial. Compared to calm breathing, V Ti, V e, P mo, IC, ΔEELV score and V e/RMS increased significantly with increasing pressure levels (all P<0.05); T e only increased significantly at 20-22 cmH 2O pressure levels compared to calm breathing ( P<0.05). P di, PTP es, PTP di, RMS and RMS/RMS max decreased significantly with increasing levels (all P<0.05). PTP es and PTP di converged to 0 and no longer showed significant changes after the 18 cmH 2O pressure level. RMS and RMS/RMS max flattened out at pressure level greater than 16 cmH 2O. T i/T tot only significantly decreased at the 20 cmH 2O pressure level compared to calm breathing. PEEPi dyn showed a tendency to decrease and then increase with increasing pressure levels. Conclusion:BiPAP ventilation, at appropriate pressure levels, significantly relieves pulmonary ventilation disorders and reduces the load of respiratory muscle in patients with stable COPD.

Fisiología respiratoria ventilación: cómo llega el aire a los alvéolos / Ventilation: how air gets into the alveoli

La principal función del aparato respiratorio es permitir el intercambio gaseoso, el cual se produce en las unidades alveolares. Para definir y conocer la ventilación alveolar, es necesario estar familiarizado con los volúmenes y capacidades pulmonares, además de conocer los principios fisiológicos que nos permiten medirlos y/o estimarlos. El objetivo de este artículo es revisar estos conceptos, para aumentar el entendimiento de la fisiología del aparato respiratorio.

The main function of the respiratory system is to allow gas exchange, which occurs in the alveolar units. To define and know alveolar ventilation, it is necessary to be familiarized with lung volumes and capacities, in addition to understand the physiological principles that allow us measure and / or estimate them. The objective of this article is to review these concepts, to increase the understanding of the physiology of the respiratory system.

The Relationship Between Job Satisfaction and Psychological/Physical Health among Malaysian Working Women

Background: The workplace environment has a great influence on employees’ health. Job dissatisfaction has been widely recognised as a workplace stressor that can influence employees’ psychological and physical health statuses. However, job satisfaction is a multi-dimensional concept, and it is necessary to investigate its different facets and their unique consequences. Therefore, the aim of this study was to assess the relationship between the nine facets of job satisfaction and psychological health and somatic complaints (i.e., sleep disorders, headache, gastro-intestinal and respiratory problems). Methods: This cross-sectional study was conducted among 567 Malaysian women working in the public sector. Data collection was conducted using a series of self-administered questionnaires. Results: The results of this study show that there is a link between job satisfaction and psychological distress as well as four somatic complaints. Satisfaction with the nature of work was the strongest predictor for psychological distress, sleep disorders, headaches and gastro-intestinal problems. Conclusion: From the results of this study, we conclude that there is a link between job satisfaction and the health status of employees. In addition, job satisfaction levels vary across different dimensions and can even differ from an individual’s feelings of global job satisfaction. Policies and practices should focus on improving working conditions to enhance the fit of the job and the employee.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 + 8.3 years old, FEV1: 49.3+19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. ClinicalTrials.gov: NCT00500864 RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Exhaled nitric oxide in neonates with or without hypoxemic respiratory failure / 世界急诊医学杂志（英文）

BACKGROUND: Exhaled nitric oxide (eNO) is one of the airway condensate derived markers, reflecting mainly airway inflammation in asthma and other lung diseases. The changes of eNO levels as pathophysiology of neonatal hypoxemic respiratory failure (HRF) in early postnatal life have not been thoroughly studied. The present study was to establish a method for measuring eNO concentrations in neonates with or without HRF. METHODS: Twenty-two newborn infants with HRF and 26 non-NRF controls were included within the first 24 hours of postnatal life. Their eNO levels were detected with a rapid-response chemiluminescence analyzer daily during the first week of their postnatal life, and lung mechanics and gas exchange efficiency were monitored at the same time, such as pulse oxygen saturation (SpO2), inspired fraction of oxygen (FiO2) and other parameters. RESULTS: During the first two days of postnatal life, eNO values of HRF neonates were significantly higher than those of the control neonates (day 1, 7.9±3.2 vs. 5.8±1.8 parts per billion [ppb], P<0.05; day 2, 8.8±3.2 vs. 6.0±2.4 ppb, P<0.05), but there were no significant differences in the following days. With SpO2/FiO2 increasing, difference of eNO values between the HRF and non-HRF neonates became narrowed, but there was still a two-fold difference of eNO/[SpO2/(FiO2×100)] on days 5-7. CONCLUSION: We established a method for measuring eNO and found difference in neonates with or without HRF, which diminished with prolonged postnatal days, reflecting pathophysiological characteristics of HRF.

Exhaled ntric xxide in nonates wth and wthout hypoxemic respiratory failure / 中华急诊医学杂志

ObjectiveTo establish a method for measuring exhaled nitric oxide (eNO)concentrations in neonates with and without hypoxemic respiratory failure ( HRF), and to investigate the relationship between eNO and respiratory parameters in neonates with HRF. Methods Twenty-two newborn infants with HRF and 26 control neonates were included within the first 24 hours of postnatal life.Their eNO levels were detected with a rapid-response chemiluminescence analyzer daily during the first week of their postnatal life, and lung mechanics and gas exchange efficiency were monitored at the same time, such as pulse oxygen saturation ( SpO2 ), inspired fraction of oxygen ( FiO2 ) and other parameters.Wilcoxon Mann-Whitney U tests were used to compare eNO, SpO2/FiO2 and eNO/ ( SpO2/FiO2 × 100) in two groups. Pearson's correlation analyses were used to determine the relationships between eNO levels and indices of hypoxemic respiratory failure. ResultsDuring the first two days of postnatal life, eNO values of HRF neonates were higher than those of the control neonates[day 1,(7. 9 ± 3.2 )× 10-9 vs. (5.8 ±1.8)×10-9, P＜0.05;day2, (8.8±3.2)×10-9vs. (6.0±2.4)×10-9, P＜0. 05], butthere were no significant differences in the following days. With SpO2/FiO2 increasing, difference of eNO values between the HRF and non-HRF controls became narrowed, but there was still two fold difference of eNO/(SpO2/FiO2 × 100) on day 5-7. ConclusionsA method for measuring eNO was established and there was difference in neonates with and without HRF, which diminished with prolonged postnatal days, reflecting pathophysiological characteristics of HRF.

A sigmoidal fit for pressure-volume curves of idiopathic pulmonary fibrosis patients on mechanical ventilation: clinical implications

OBJECTIVE: Respiratory pressure-volume curves fitted to exponential equations have been used to assess disease severity and prognosis in spontaneously breathing patients with idiopathic pulmonary fibrosis. Sigmoidal equations have been used to fit pressure-volume curves for mechanically ventilated patients but not for idiopathic pulmonary fibrosis patients. We compared a sigmoidal model and an exponential model to fit pressure-volume curves from mechanically ventilated patients with idiopathic pulmonary fibrosis. METHODS: Six idiopathic pulmonary fibrosis patients and five controls underwent inflation pressure-volume curves using the constant-flow technique during general anesthesia prior to open lung biopsy or thymectomy. We identified the lower and upper inflection points and fit the curves with an exponential equation, V = A-B.e-k.P, and a sigmoid equation, V = a+b/(1+e-(P-c)/d). RESULTS: The mean lower inflection point for idiopathic pulmonary fibrosis patients was significantly higher (10.5 ± 5.7 cm H2O) than that of controls (3.6 ± 2.4 cm H2O). The sigmoidal equation fit the pressure-volume curves of the fibrotic and control patients well, but the exponential equation fit the data well only when points below 50 percent of the inspiratory capacity were excluded. CONCLUSION: The elevated lower inflection point and the sigmoidal shape of the pressure-volume curves suggest that respiratory system compliance is decreased close to end-expiratory lung volume in idiopathic pulmonary fibrosis patients under general anesthesia and mechanical ventilation. The sigmoidal fit was superior to the exponential fit for inflation pressure-volume curves of anesthetized patients with idiopathic pulmonary fibrosis and could be useful for guiding mechanical ventilation during general anesthesia in this condition.

Estudio explorativo acerca de la utilidad del cociente respiratorio en la determinación del umbral anaeróbico en pacientes con unsuficiencia renal crónica / Exploratory study about the utility of the respiratory quotient on the determination of anaerobic threshold on chronic kidney disease patients

Fundamento y Objetivo: Debido a las alteraciones observadas en la condición física de pacientes con insuficiencia renal crónica se ha demostrado la utilidad de someter a estos pacientes a un entrenamiento físico. El cociente respiratorio es utilizado normalmente como un medio no invasivo para estimar el umbral anaeróbico en sujetos sometidos a entrenamiento físico. Este estudio tuvo como objetivo evaluar la utilidad del cociente respiratorio como método indirecto para estimar el umbral anaeróbico y como indicador de detención en una ergometría en pacientes con insuficiencia renal crónica. Pacientes y método: Se realizó una cicloergometría con análisis de gases espirados en un grupo de pacientes con insuficiencia renal crónica (n=17) y en un grupo de sujetos sanos (n=18). Los cocientes respiratorios en reposo y con 30, 60 y 100 W fueron comparados entre ambos grupos. Resultados: No se observaron diferencias entre individuos sanos y pacientes en el cociente respiratorio en reposo; sin embargo, durante la prueba con diferentes intensidades de trabajo se observaron diferencias estadísticamente significativas entre ambos grupos. Conclusiones: En el caso de los nefrópatas, las diferencias observadas en el cociente respiratorio pueden atribuirse a exceso de producción de CO2. Per esta razón, la utilización del cociente respiratorio como un medio no invasivo para estimar el umbral anaeróbico parece ser no recomendable en pacientes con insuficiencia renal crónica.

Background and Objective: Due to changes observed in the physical condition of patients with chronic renal failure it has been demonstrated the usefulness of the physical training on these patients. The respiratory quotient is normally used as a non-invasive method for estimating the anaerobic threshold in subjects undergoing physical training. This study aimed to evaluate the usefulness of the respiratory quotient as an indirect method to estimate the anaerobic threshold and as an indicator to stop the ergometry in patients with chronic renal failure. Patients and Methods: We conducted a cycle-erge metry with expired gas analysis in patients with chronic renal failure (n = 17) and in a group of healthy subjects (n= 18). The respiratory quotients at rest and with 30, 60 and 100 W were compared between groups. Results: No differences in the respiratory quotient were observed between healthy subjects and patients at rest, however, statistically significant differences were found between groups with different intensities of work. Conclusions: Because the observed differences in respiratory quotients could be attributed to an excess on production of CO2 in chronic renal failure patients, the use of respiratory quotient as a non-invasive method for estimating the anaerobic threshold seems to be not recommended in these patients.

Pressão positiva contínua nas vias aéreas: modo ventilatório / Continuous positive airway pressure: mode of ventilation

Objetivo Avaliar se a pressão positiva contínua nas vias aéreas promove alterações fisiológicas nas variáveis respiratórias que a caracterizam como um modo ventilatório e comparálas com a pressão de suporte. Métodos Trata-se de um estudo prospectivo com 39 indivíduos adultos sadios, voluntários, realizado em um hospital universitário terciário. Todos os voluntários foram monitorizados em respiração espontânea com o monitor CO2SMO - Dixtal. Posteriormente, o modo pressão de suporte foi ajustado em 5cmH2O acima da pressão positiva expiratória final (de igual valor). Após sete dias, os indivíduos foram submetidos aos mesmos procedimentos, porém com a aplicação de pressão positiva contínua nas vias aéreas de 7cmH2O. O ventilador utilizado foi da marca Dragër, modelo Savina®. Resultados Dentre as variáveis respiratórias, foram observados aumento nos volumes minuto e minuto alveolar, nos picos de fluxo inspiratório e expiratório e na saturação periférica de oxigênio. O volume corrente foi similar com ambos os modos, porém o gás carbônico expirado foi menor na pressão de suporte, quando comparado com a respiração espontânea. Isto pode ser justificado pelo aumento na freqüência respiratória nesse modo. Conclusão Em voluntários saudáveis, a pressão positiva contínua nas vias aéreas induz a variações fisiológicas similares nos parâmetros respiratórios, tais como a pressão de suporte, quando a pressão média das vias aéreas é correspondente. Se o critério considerado para modalidade ventilatória é a variação no volume corrente e freqüência respiratória, dentre outras variáveis, pode-se concluir que a pressão positiva contínua nas vias aéreas é um tipo de modo ventilatório

Objective The objective of this study was to assess if continuous positive airway pressure promotes physiological changes in the respiratory variables that characterize it as a mode of ventilation and compare it with pressure support ventilation. Methods This is a prospective study with 39 adult, healthy volunteers done in a tertiary university hospital. All volunteers were monitored while breathing spontaneously with the monitor CO2SMO - Dixtal. Later, the pressure support mode was adjusted in 5cmH2O above the positive end-expiratory pressure (of same value). After seven days, the individuals were submitted to the same procedures, however with application of a continuous positive airway pressure of 7cmH2O. The ventilator brand was Dragër, model Savina®. Results The following respiratory variables increased: minute volume, alveolar minute volume, peak inspiratory and expiratory flows and saturation of peripheral oxygen. Tidal volume was similar in both modes but expired carbon dioxide was smaller during pressure support when compared with spontaneous breathing. This may be explained by the increased respiratory rate in this mode. Conclusion In healthy volunteers, continuous positive airway pressure induces similar physiological variations in respiratory parameters, such as pressure support when mean airway pressure corresponds. If the criterion considered for mode of ventilation is variation in tidal volume and respiratory rate among other variables, one can conclude that continuous positive airway pressure is a type of mode of ventilation

Strategies for cardiopulmonary exercise testing of pectus excavatum patients: [review]

The purpose of this paper is to provide strategies for cardiopulmonary exercise testing of pectus excavatum patients. Currently, there are no standardized methods for assessing cardiovascular and pulmonary responses in this population; therefore, making comparisons across studies is difficult if not impossible. These strategies are intended for physicians, pulmonary technicians, exercise physiologists, and other healthcare professionals who conduct cardiopulmonary exercise testing on pectus excavatum patients. By using the strategies outlined in this report, comparisons across studies can be made, and the effects of pectus excavatum on cardiopulmonary function can be assessed with greater detail.

Avaliação da utilização de sistema de suspensão abdominal mecânica: estudo experimental em cães / Evaluation of abdominal wall lifting system utilization: experimental study in dogs

Com o intuito de avaliar sistema de suspensão mecânica da parede abdominal, elaborou-se protocolo experimental, estudando-se trinta cães, distribuídos em três grupos experimentais de maneira aleatória: grupo pneumoperitônio com gás carbônico, grupo suspensão pela cavidade peritoneal e grupo suspensão abdominal (intraperitoneal) pela tela subcutânea, para documentar alterações metabólicas, hemodinâmicas e respiratórias em cada grupo, compará-las e verificar possíveis vantagens ou desvantagens dos métodos. Os animais foram monitorizados com eletrocardiograma, cateter de Swan-Ganz e pressão arterial invasiva, sendo colhidas amostras de sangue arterial e venoso misto nos momentos basal, 0, 15, 30, 60, 90, 120 minutos e 30 minutos após o término do procedimento, anotando-se para cada momento os parâmetros hemodinâmicos. Calculouse a média e o desvio padrão dos parâmetros, sendo os diferentes grupos comparados pelo teste de Kruskal-Wallis, e nos momentos em que se encontrou diferença estatística entre os três grupos, comparou-se os grupos dois a dois pelo teste de Mann-Whitney. Observou-se, no grupo pneumoperitônio em relação aos grupos suspensão, queda significativa do pH sangüíneo, elevação do bicarbonato, elevação da pressão venosa central e elevação da pressão parcial de gás carbônico, diferenças estas estatisticamente significativas, com p<0,05, não havendo diferenças estatísticas entre os grupos suspensão abdominal e subcutânea.

With the purpose of evaluate abdominal wall lifting system, a experimental protocol was elaborated, and thirty dogs, distributed randomly in three experimental groups, pneumoperitoneum with carbon dioxide gas, abdominal (intraperitoneal) suspension and subcutaneous suspension, were studied to document metabolic, hemodynamic and respiratory alterations, compare then and verify if there are some advantage or disadvantage in each method. The animals were monitored with electrocardiogram, Swan-Ganz catheter and invasive arterial blood pressure, and samples of arterial and venous blood were collected at the moments basal, 0, 15, 30, 60, 90 and 120 minutes, and 30 minutes after the end of procedure, registering at each moment the hemodynamical parameters. The three groups were statically compared with Kruskal-Wallis test and, at the moments with statistical differences, the groups were compared two by two with Mann-Whitney test. At the group pneumoperitoneum was observed significant decrease of blood pH, raising of bicarbonate, central venous pressure, and partial carbon dioxide blood pressure in relation to suspension groups, and those differences were statistically significant with p<0.05, without significant differences between abdominal and subcutaneous suspension groups.

Sistema tutorial para el estudio de la fisiología del aparato respiratorio del cuerpo humano / Tutorial system for studying the physiology of the human body's respiratory system

Para dar respuesta al problema que presentan los estudiantes de Ciencias Médicas con el nivel de abstracción necesario para la comprensión de los complejos procesos originados en el interior del cuerpo humano, entre de los que se encuentra la respiración, se realizó un análisis entre los profesores de los departamentos de Fisiología y Computación atendiendo el criterio de los estudiantes de años superiores, y se concluyó que era posible aplicar una solución computadorizada, unida a cierta estrategia pedagógica que puediera constituir una alternativa viable para resolver las dificultades existentes. Se explica cómo fue concebido y ejecutado el proyecto; lo que permite conocer diversos enfoques teóricos actuales sobre la utilización de la enseñanza asistida por computadoras, estrategia pedagógica seguida y características del sistema, entre otros aspectos de interés. Se realizó con éxito la validación del sistema con profesores de Fisiología y Computación y un grupo de estudiantes de Medicina

To give an answer to the problem the medical students have with the level of abstraction necessary to comprehend the complex processes originated inside the human body, such as respiration, it was made an analysis among the professors of the departments of Physiology and Computers, taking into account the criterion of students from higher years. It was concluded that it was possible to apply a computerized solution, together with certain pedagogical strategy that may be an alternative to solve the existing difficulties. It was explained how the project was designed and implemented, which allowed to know diverse current theoretical approaches on the utilization of computer-assisted education, the pedagogical strategy followed and the characteristics of the system, among other aspects of interest. The validation of the system was successfully carried out with professors of Physiology and Computers and a group of medical students.

The study of the relationship between the angiotensin-converting enzyme gene insertion/deletion polymorphism and the cardiorespiratory fitness / 中华老年医学杂志

Objective To explore the relationship between the angiotensin-converting enzyme(ACE) gene inserton/deletion(I/D) polymorphism and the cardiorespiratory fitness. Methods One hundred twenty six male subjects were recruited and randomized into a physical exercise(n=65) or a control group(n=61).The men in the physical exercise group were trained with mild-moderate intensity physical exercise for 5 years. The men in the control group were advised to make their personal choice whether or not to engage in physical exercise. The cardiorespiratory fitness indices,e.g. aerobic threshold were measured at baseline and annually. The I/D polymorphism in the 16 th intron of ACE gene was analysed by polymerase chain reaction. Results At baseline, the aerobic threshold was (14.4 ? 3.9)ml?min -1?kg -1 in the physical exercise group. After 5-year physical exercise, the aerobic threshold was (16.4 ? 4.1)ml?min -1?kg -1in the physical exercise group. At baseline, the aerobic thresholds was(14.2 ?3.6)ml?min -1?kg -1in the control group. After 5 years, the aerobic threshold was(13.8 ? 3.3)ml?min -1?kg -1in the control group. After 5 year physical exercise, compared with the baseline and the control group, the aerobic threshold increased significantly in the physical exercise group(both,P0.05). Conclusions Regular low to moderate intensity physical exercise can increase aerobic threshold and improve cardiorespiratory fitness. Compared with the subjects with the ACE DD genotypes, the cardiorespiratory fitness can be improved more easily for the subjects with the ACE II,ID genotypes.

Mechanism of increasing airway ciliary beating frequency by L-arginine / 中华麻醉学杂志

Objective To understand the modulating mechanisms in ciliary motility by NO signal pathway. Methods L arginine, the preferred substrate of NOS, was employed to act upon the cultured rat ciliated epithelia. After pre incubating with L NMMA, a NOS inhibitor, or ODQ,a sGC inhibitor, or Rp 8 Br cGMPS, an antagonist of PKG respectively, tissues were contacted with L arginine again. Ciliary beating frequency (CBF) was measured by phase contrast microscope and videotape analysis. Results L arginine increased CBF siginficantly. The effect of L arginine on CBF was blocked by L NMMA, ODQ or Rp 8 Br cGMPS.Conclusion L arginine may increase CBF via NO sGC cGMP PKG pathway.

Efeito do propranolol e metoprolol nas respostas cárdio-respiratórias e metabólicas ao exercício / Effects of propranolol and metoprolol on cardiorespiratory And metabolic responses to exercise.

PurposeTo study the effects of intravenous propranolol and metoprolol on cardiorespiratory and metabolic responses to exercise. MethodsTwo groups of anaesthetized dogs (sodium pentobarbital, 33 mg/kg) were studied at rest and moderate exercise (induced by electrical stimulation) before and after metoprolol (0.4 mg/ Kg, n = 7) or propranolol (0.2 mg/kg, n = 10). Haemodynamic, metabolic and respiratory variables were measured. ResultsThere was a decrease in heart rate both at rest and during exercise after metoprolol and propranolol administration. The cardiac output, stroke volume and peripheral vascular resistance presented decreased responses to exercise after both drugs. O2 consumption and CO2 production were not altered signifcantly at rest but increased in a lesser degree during exercise. Propranolol administration reduced ventilation during rest and exercise, although the ventilatory response to exercise remained the same. Metoprolol administration did not affect ventilation at rest but reduced the ventilatory response to exercise leading to an increase of the PaCO2 Conclusion Propranolol and metoprolol effects on cardiovascular and metabolic variables measured at rest and during exercise were the same. The ventilatory effect with metoprolol administration was different from the observed with propranolol