Lung Function and Exercise Performance in Hyperthyroidism Before and After Treatment

In order to investigate the mechanism of dyspnoea in hyperthyroidismmeasurements of spirometry, lung volume, transfer factor forcarbon monoxide and its subdivisions, maximal respiratory pressures,methacholine challenge, arterial blood gases were made and exercisestudies performed on 16 patients before treatment for hyperthyroidism.Methacholine challenge showed that only three of 14 patientsincreased airway reactivity, which was mild. Maximal pressureswhich could be generated by the respiratory muscles were reducedin some patients, as was functional residual capacity. Exerciseventilation and breathing frequency were increased and the respiratoryexchange ratio was abnormally high. Anaerobic threshold wasmeasured in nine of 15 subjects and was below normal in eachcase. All but two subjects stopped exercise because of dyspnoea,and the maximum oxygen uptake achieved by the group was 53 percent (n=15, range 26–66 per cent) of predicted maximumoxygen consumption. The maximum ventilation averaged only 43per cent (n=15, range 16–96 per cent) of the maximal breathingcapacity predicted from spirometric tests. Nine patients were studied shortly after being rendered euthyroidby treatment. At rest, only maximal respiratory pressures increasedsignificantly. On exercise, the maximal workload attained andthe ventilation achieved increased significantly. Breathingpatterns, maximal oxygen consumption, ventilation, anaerobicthreshold and cardiac frequency remained unchanged. We conclude that: patients with hyperthyroidism do not generallyhave increased airway reactivity; when hyperthyroid, respiratorymuscles are weak, and improve following treatment; exercisecapacity is impaired in hyperthyroid patients probably becauseof a combination of an inefficiently rapid and shallow breathingpattern, an increase of anaerobic metabolism and discomfortassociated with the act of breathing. Although exercise capacityincreases and the sensation of dyspnoea may decrease after treatmentthe pattern of breathing does not immediately return to normal.     

Dissociation between respiratory effort and dyspnoea in a subset of patients with stroke

Dyspnoea is not a prominent complaint of resting patients with recent hemispheric stroke (RHS). We hypothesized that, in patients with RHS presenting abnormalities in respiratory mechanics, increased respiratory motor output could translate into an increased perception of dyspnoea. We studied eight wheelchair-bound patients with RHS (mean age 62.4 years), previously evaluated by computerized tomography scanning, and a control group of normal subjects, matched for age and sex. We assessed routine spirometry, inspiratory and expiratory muscle pressures, breathing pattern and dyspnoea using a modified Borg scale. In six patients, we also measured oesophageal pressure during the maximal sniff manoeuvre and tidal inspiratory swing, and mechanical characteristics of the lung in terms of dynamic elastance during both quiet breathing and a hypercapnic/hyperoxic rebreathing test. During room air breathing, ventilation and tidal volume were similar in patients and controls, while tidal inspiratory swings of oesophageal pressure, an index of inspiratory motor output, were greater in patients ( P =0.005). Patients also exhibited a greater dynamic elastance ( P =0.013). During rebreathing, dynamic elastance remained higher ( P =0.01) and a greater than normal inspiratory motor output was found ( P =0.03). Responses of ventilation and tidal volume to carbon dioxide tension were normal, and in all patients but one a lower Borg score for the unit change in carbon dioxide tension and ventilation was found. In conclusion, a higher than normal inspiratory motor output was unexpectedly associated with a blunted perception of dyspnoea in this subset of RHS patients. This is likely to be due to the modulation of the integration process of respiratory sensation.     

Aerobic and anaerobic exercise training in obese adults

[Purpose] Obesity is a global health problem and is associated with a multitude of complications. This study was designed to determine changes in cardiopulmonary functions after aerobic and anaerobic exercise training in obese subjects. [Subjects and Methods] Forty obese subjects, whose ages ranged between 18 and 25 years, were divided into 2 equal groups: group A received aerobic exercise training in addition to dietary measures, and group B received anaerobic exercise training for 3 months in addition to dietary measures. Measurements of systolic blood pressure, diastolic blood pressure, heart rate, maximum voluntary ventilation, maximal oxygen consumption, and body mass index were obtained for both groups before and after the exercise program. [Results] The mean body mass index, systolic blood pressure, diastolic blood pressure, heart rate, and maximal oxygen consumption decreased significantly, whereas the mean maximum voluntary ventilation increased significantly after treatment in group A. The mean maximum voluntary ventilation also increased significantly after treatment in group B. There were significant differences between the mean levels of the investigated parameters in groups A and B after treatment. [Conclusion] Aerobic exercise reduces weight and improves cardiopulmonary fitness in obese subjects better than anaerobic exercise.Key words: Obesity, Aerobic, Anaerobic     

Respiratory muscle performance as a possible determinant of exercise capacity in patients with ankylosing spondylitis

Reduction of exercise capacity in patients with ankylosing spondylitis is associated with skeletal muscle performance. The contribution of respiratory muscle performance is questionable. This pilot study was designed to investigate the relationship between respiratory muscle performance and exercise capacity in ankylosing spondylitis. Subjects were 12 patients with ankylosing spondylitis. Measurements of maximal respiratory pressures and inspiratory muscle endurance were performed and correlated with maximal exercise capacity. Lung function and chest wall expansion were reduced on average. Maximal inspiratory and expiratory pressures were reduced to 82 +/- 20% of predicted values and 75 +/- 22% of predicted values respectively. On average there was no reduction in inspiratory muscle endurance which remained at 103 +/- 36% of predicted values. No overall reduction was found in maximal exercise capacity, either expressed as maximal workload or as peak oxygen uptake; however, a wide range was found. Maximal workload and peak oxygen uptake correlated significantly with maximal respiratory pressures and respiratory muscle endurance. The best regression model for explaining the total variation of maximal workload and peak oxygen uptake selected maximal inspiratory pressures as the independent variable (r(2) = 59.6%, p = 0.003 and r(2) = 62.5%, p = 0.05 respectively.) These data suggest respiratory pressure and respiratory muscle endurance, in particular maximal inspiratory pressure, may be determinants of exercise capacity in patients with ankylosing spondylitis.     

Ventilation and breathlessness on maximal exercise in patients with interstitial lung disease after local anaesthetic aerosol inhalation

1. The ventilatory response to maximal incremental exercise and the accompanying sensation of breathlessness were studied after the inhalation of 0.9% sodium chloride (saline) and 5% bupivacaine aerosols in six patients with interstitial lung disease. 2. The adequacy of airway anaesthesia induced by bupivacaine aerosol was confirmed by the absence of the cough reflex to 5% citric acid aerosol on completion of exercise. 3. All subjects first performed a trial exercise test to familiarize them with the procedure and to assess the degree of arterial oxygen desaturation on exercise. In subsequent tests, supplementary oxygen was given to maintain the saturation at 95% or above. 4. Airway anaesthesia had no effect on the ability to perform exercise as assessed by maximum workload, CO2 production or heart rate. No significant changes were seen on the pattern of breathing, minute ventilation or end-tidal PCO2 on exercise. There was, however, a small but statistically significant increase in ventilation related to CO2 production (VE/VCO2) at the end of exercise. 5. There was a tendency for breathlessness to be increased by airway anaesthesia but this did not reach statistical significance. 6. These results provide no evidence that vagal afferent activity is responsible for the abnormal ventilatory response to exercise in patients with interstitial lung disease. The perception of breathlessness in these patients was not diminished by anaesthesia of the airway.     

Bilevel Exercise Training and Directed Breathing Relieves Exertional Dyspnea for Male Smokers

OBJECTIVE: The purpose of this study was to compare the effects on exertional dyspnea and exercise capacity of square wave (bilevel) cycle ergometry endurance exercise training (SWEET) and comprehensive directed breathing vs. walking while pushing an OxCar and traditional diaphragmatic breathing for male smokers with normal spirometry but reduced exercise capacity. DESIGN: This was a prospective randomized trial of 24 unmedicated men with exertional dyspnea assigned to SWEET or OxCar groups. Exertional dyspnea was assessed using the Borg scale during four tests: incremental exercise, constant exercise at 80% of the peak work rate (PWR) (maximum tolerated for 3 mins before exhaustion), SWEET, and 6-min walk test. Both groups trained for 45 mins, 5 days a week, for 6 wks. Before, during, and after training, 32 lung function parameters were studied at ventilatory anaerobic threshold, at PWR, and during incremental exercise (30 W/3 mins). RESULTS: For the SWEET group, exertional dyspnea and the dyspnea index decreased during incremental exercise, at the ventilatory anaerobic threshold, and at PWR (P < 0.01). At the ventilatory anaerobic threshold, oxygen consumption increased by 74%; minute ventilation, 30%; tidal volume, 91%; and ventilatory efficiency and oxygen pulse (O2P), 25%; and breathing rate (breathing frequency) decreased by 32% (all significant at P < 0.001). At PWR, oxygen consumption increased by 30%; minute ventilation, 37%; breathing rate, 21%; and ventilatory efficiency and oxygen pulse, 25% (P < 0.01). During the full incremental test, minute ventilation, breathing frequency, and heart rate (cardiac frequency) decreased significantly (P < 0.01). In addition, there was significant improvement (P < 0.001) in SWEET intensity by 63%, constant exercise intensity at 80% of PWR by 38%, and 6-min walk test by 30%. No significant changes were observed for the OxCar group other than for the 6-min walk test, which increased by 7% (P < 0.05). CONCLUSIONS: This study suggests that the decline in exercise tolerance for male smokers can be reduced by intensive exercise training (SWEET) and comprehensive directed breathing but not by moderate training and traditional diaphragmatic breathing. Thus, some smokers can be helped despite continuing to smoke.     

The ventilatory cost of exercise compared in chronic heart failure and chronic renal anaemia.

The cardiorespiratory responses to maximal treadmill exercise were compared in matched groups of patients with chronic renal anaemia or treated chronic heart failure, and in normal controls. Exercise capacity was similarly reduced in both patient groups compared to normal controls, the raised respiratory exchange ratio at peak exercise implying anaerobic metabolism due to limited oxygen delivery in heart failure and limited oxygen carrying capacity in anaemia. Minute ventilation (VE) was related linearly to minute CO2 production (VCO2) in all subjects (each r > 0.92) from all three groups. The slope of the VE/VCO2 relationship was normal in anaemia but steeper in heart failure, reflecting ventilation/perfusion mismatching in chronic heart failure.     

Cardiorespiratory responses to upper extremity aerobic training by postpolio subjects.

The cardiorespiratory responses of ten postpolio subjects participating in a 16-week upper extremity aerobic exercise program were compared to ten non-exercised controls. The subjects trained three times a week for 20 minutes per session. Exercise intensity was prescribed at 70% to 75% of heart rate reserve plus resting heart rate. Dependent variables were resting heart rate, maximal heart rate, resting and immediate-post-exercise systolic and diastolic blood pressures, maximal oxygen consumption, maximal carbon dioxide production, minute ventilation, respiratory exchange ratio, power, and exercise time. After training, the exercise group was superior to the control group in oxygen consumption, carbon dioxide production, minute ventilation, power, and exercise time. There was no reported loss of muscle strength. It was concluded that postpolio subjects can safely achieve an increase in aerobic capacity with a properly modified upper extremity exercise program. This improvement is comparable to that demonstrated by able-bodied adults.     

皮肌炎患者呼吸中枢兴奋性的测定

目的 了解皮肌炎患者呼吸中枢——肺的功能变化。方法 分别测定了22例皮肌炎患者及20例正常人的用力肺活量(FVC)、1秒钟用力呼气容积(FEV1)、最大呼气流量(PEF)、最大呼气中段流量(MMEF)、25％肺活量最大呼气流量(V25)、肺一氧化碳弥散量(DLCO)、最大吸气口腔压(PImax)及口腔阻断压(P0.1)等参数。结果 皮肌炎患者反映肺通气功能指标FVC、V25、MMEF及肺弥散功能指标DLCO均明显低于正常人，呼吸中枢兴奋性指标P0.1则显著高于正常人，而吸气肌肌力(PImax)与正常组比差异无统计学意义。结论 皮肌炎患者在肺通气及弥散功能降低的基础上，存在着呼吸中枢兴奋性的增高。     

Specific compliance and gas exchange during high-frequency oscillatory ventilation

OBJECTIVES: To evaluate the use of specific compliance (static compliance/functional residual capacity) to adjust mean airway pressure, resulting in optimal gas exchange during high-frequency oscillatory ventilation in a surfactant-deficient newborn piglet. DESIGN: Prospective controlled animal study. SETTING: Laboratory. SUBJECTS: Eight newborn piglets at 5 days of age. BACKGROUND: High-frequency oscillatory ventilation enables the use of relatively high mean airway pressures without the lung damage associated with conventional positive pressure ventilation. Mean airway pressures can be increased, resulting in static lung expansion that approaches total lung capacity with its negative impact on venous return. Therefore, knowledge of lung volume is important for safe patient management. A simple, noninvasive technique to enable the clinician to determine the optimal mean airway pressure likely would improve patient management. INTERVENTIONS: The lungs were lavaged after placement of central catheters and tracheostomy to lower respiratory system compliance and worsen ventilation perfusion matching. The animals were ventilated with high-frequency oscillatory ventilation at the same mean airway pressure as before lung lavage. Mean airway pressures then were increased in a step-wise fashion up to 30 cm H2O or until clinical deterioration occurred. All other ventilator variables, Fio2, frequency, and pressure amplitude were constant throughout the experiment. MEASUREMENTS AND MAIN RESULTS: Before lavage and at each level of mean airway pressure after lung lavage, respiratory system compliance and functional residual capacity were measured. Additionally, central arterial pressure, central venous pressure, heart rate, arterial blood gas, and pulse oximetric saturation were recorded. Lung lavage significantly lowered respiratory system compliance (static as well as specific compliance) and worsened ventilation perfusion matching as evidenced by an increase in Paco2 and a decreased arterial to alveolar oxygen ratio. With increasing mean airway pressures, static/specific compliance improved and then peaked before declining, functional residual capacity increased, and blood gas improved until reaching the flat portion of the pressure-volume relationship of the lung. Optimal gas exchange as reflected by the highest arterial to alveolar oxygen ratio and lowest Paco2 at constant ventilation was found at a mean airway pressure that maintained the functional residual capacity and static respiratory system compliance at the same level as the preinjury levels ("normalized" functional residual capacity and respiratory system compliance). CONCLUSIONS: These results suggest that specific compliance measurement that incorporates static respiratory system compliance and functional residual capacity during high-frequency oscillatory ventilation can be used to adjust mean airway pressure and achieve "normalized" functional residual capacity, static compliance, and gas exchange. These measurements may provide a simple method to optimize lung volume in a surfactant-deficient patient during high-frequency oscillatory ventilation.     

Endurance training in patients with chronic obstructive pulmonary disease: a comparison of high versus moderate intensity

PURPOSE: To create a maximum tolerated 45-minute aerobic training program for patients with chronic obstructive pulmonary disease (COPD) and to compare its outcomes with those of commonly prescribed moderate exercise. DESIGN: Prospective, randomized trial. SETTING: A work physiology laboratory. PATIENTS AND METHODS: The maximum exercise intensities that 7 COPD patients could sustain for 45 minutes were determined on a bilevel exercise ergometer. The patients then exercised 45 minutes daily, 5 days a week for 6 weeks, working 2.03+/-0.4 kJ/kg per session. They were matched with 6 COPD patients who pushed an O2 cart for 45 minutes daily, 5 days a week for 6 weeks, working 1.44+/-.35 kJ/kg per session. RESULTS: A 45 minute maximal regimen was established by alternating 1-minute peak exercise at peak VO2-levels with 4 minutes at the ventilatory anaerobic threshold or at 40% of peak VO2. Maximal bilevel training significantly decreased dyspnea at rest (p< or =.01) and the blood lactate level during submaximal exercise (p<.001), and increased peak VO2 and total physical work (p<.01), maximum inspiratory and expiratory pressures (p<.01), and grip and forearm strength and endurance (p<.01). The training also increased maximum voluntary ventilation while decreasing the ventilatory equivalent during exercise (p<.001). The O2 cart pushers significantly improved only on the 12-minute walk (p<.05). CONCLUSIONS: A maximally intense anaerobic exercise program can be created for most COPD patients that can significantly improve both skeletal and respiratory muscle strength and endurance as well as dyspnea and physiologic parameters.     

Mechanisms of impaired exercise capacity in short duration experimental hyperthyroidism.

To investigate the mechanism of reduced exercise tolerance in hyperthyroidism, we characterized cardiovascular function and determinants of skeletal muscle metabolism in 18 healthy subjects aged 26 +/- 1 yr (mean +/- SE) before and after 2 wk of daily ingestion of 100 micrograms of triiodothyronine (T3). Resting oxygen uptake, heart rate, and cardiac output increased and heart rate and cardiac output at the same submaximal exercise intensity were higher in the hyperthyroid state (P less than 0.05). However, maximal oxygen uptake decreased after T3 administration (3.08 +/- 0.17 vs. 2.94 +/- 0.19 l/min; P less than 0.001) despite increased heart rate and cardiac output at maximal exercise (P less than 0.05). Plasma lactic acid concentration at an equivalent submaximal exercise intensity was elevated 25% (P less than 0.01) and the arteriovenous oxygen difference at maximal effort was reduced (P less than 0.05) in the hyperthyroid state. These effects were associated with a 21-37% decline in activities of oxidative (P less than 0.001) and glycolytic (P less than 0.05) enzymes in skeletal muscle and a 15% decrease in type IIA muscle fiber cross-sectional area (P less than 0.05). Lean body mass was reduced (P less than 0.001) and the rates of whole body leucine oxidation and protein breakdown were enhanced (P less than 0.05). Thus, exercise tolerance is impaired in short duration hyperthyroidism because of decreased skeletal muscle mass and oxidative capacity related to accelerated protein catabolism but cardiac pump function is not reduced.     

Effects of sympathetic inhibition on exertional dyspnoea, ventilatory and metabolic responses to exercise in normotensive humans.

Augmentation of circulating noradrenaline concentration stimulates ventilation during the initial stages of exercise and this is accompanied by an increased sensation of dyspnoea and exertion. This previous study [Clark, Galloway, MacFarlane, Henderson, Aitchison and McMurray (1997) Eur. Heart J. 18, 1829-1833] suggested a link between dyspnoea, which commonly limits exercise tolerance in heart failure patients, and high circulating noradrenaline concentration in these patients. The present study investigated this relationship further using sympathetic inhibition. Ten healthy normotensive males performed 10 min of submaximal cycling exercise at approx. 70% of maximal oxygen uptake per min (VO2max) on three occasions one week apart. The first of these sessions was a familiarization session and the other two were experimental study days. On each of the study days, subjects attended the laboratory in the morning after an overnight fast and, following a resting blood sample, were administered placebo or moxonidine (0.4 mg) in a double blind cross-over design. After a 90-min absorption period, subjects undertook the exercise task. Blood was drawn, expired gas was analysed breath by breath, blood pressure, heart rate and ratings of perceived dyspnoea and exertion were obtained. Moxonidine treatment significantly reduced plasma noradrenaline concentration (P < 0.01), mean arterial pressure (P < 0.01), and blood glycerol concentration (P < 0.05), but no differences were observed in heart rate, the ventilatory response to exercise or subjective ratings of dyspnoea and exertion. This study indicates that reducing sympathetic activity does not affect ventilation, perceived dyspnoea or perceived exertion in normotensive males. Therefore it can be concluded that reducing sympathetic activity may not be an appropriate strategy to help reduce perceived dyspnoea.     

重度肥胖对肺功能及运动试验中呼吸模式的影响

目的：研究重度肥胖对肺胖对肺功能及运动试验中呼吸模式的影响。方法：４２名女性受试者,正常体重组２０名,重度肥胖组２２名,进行肺功能及功率车运动试验测定。结果：肥胖组补呼气量、功能残气量、残气量及肺总量均比对照组显著降低（Ｐ〈０．０５）。肥胖组静息状态、无氧阈状态和极量运动状态的氧耗量均比对照组显著增高（Ｐ〈０．０５）,而公斤氧耗量比对照组显著降低（Ｐ〈０．０１）。无氧阈状态和极量运动状态时,肥胖组     

Influence of Taekwondo as Security Martial Arts Training on Anaerobic Threshold,Cardiorespiratory Fitness,and Blood Lactate Recovery

[Purpose] This study was conducted to determine the influence of Taekwondo as security martial arts training on anaerobic threshold, cardiorespiratory fitness, and blood lactate recovery. [Subjects and Methods] Fourteen healthy university students were recruited and divided into an exercise group and a control group (n = 7 in each group). The subjects who participated in the experiment were subjected to an exercise loading test in which anaerobic threshold, value of ventilation, oxygen uptake, maximal oxygen uptake, heart rate, and maximal values of ventilation / heart rate were measured during the exercise, immediately after maximum exercise loading, and at 1, 3, 5, 10, and 15 min of recovery. [Results] At the anaerobic threshold time point, the exercise group showed a significantly longer time to reach anaerobic threshold. The exercise group showed significantly higher values for the time to reach VO_2max, maximal values of ventilation, maximal oxygen uptake and maximal values of ventilation / heart rate. Significant changes were observed in the value of ventilation volumes at the 1- and 5-min recovery time points within the exercise group; oxygen uptake and maximal oxygen uptake were significantly different at the 5- and 10-min time points; heart rate was significantly different at the 1- and 3-min time points; and maximal values of ventilation / heart rate was significantly different at the 5-min time point. The exercise group showed significant decreases in blood lactate levels at the 15- and 30-min recovery time points. [Conclusion] The study results revealed that Taekwondo as a security martial arts training increases the maximal oxygen uptake and anaerobic threshold and accelerates an individual’s recovery to the normal state of cardiorespiratory fitness and blood lactate level. These results are expected to contribute to the execution of more effective security services in emergencies in which violence can occur.Key words: Security martial arts, Taekwondo, Anaerobic threshold     

呼吸操锻炼对小儿脊柱侧弯术前肺功能的影响

背景小儿脊柱侧弯患者术后易发生急性呼吸功能不全的危险,术前进行综合呼吸操锻炼对其预防的效果尚未确定.目的探讨呼吸操锻炼对小儿脊柱侧弯患者术前应用的可行性和有效性.设计非随机横断面研究.地点、对象和方法选择上海长海医院对35例脊柱侧弯且肺功能障碍9～15岁住院患儿.术前1周对脊柱侧弯患儿实施组合的呼吸操训练,其内容包括缩唇呼吸、腹部运动呼吸、膈肌呼吸、吹气球.同时记录观察比较锻炼前后肺功能的变化.主要观察指标呼吸操锻炼前后患儿肺活量、肺容量、用力肺活量(forced ventilation capacity,FVC)、最大通气量(maximal ventilation volume,MVV)的变化.结果锻炼后患儿肺功能检查各项指标[肺活量,肺容量,FVC,MVV分别为(2.65±0.29),(3.56±0.79),(2.41±0.41),(70.1±17.0)L]比锻炼前[(1.77±0.36),(2.67±0.84),(2.07±0.46),(52.5±14.0)L]明显改善(t=3.64～11.28.P<0.01).结论术前进行呼吸操锻炼能改善患儿肺功能,提高对脊柱矫形手术的耐受力,对预防和减少术后呼吸功能不全的发生有积极作用.     

脑卒中昏迷患者应用口咽通气管的疗效观察

目的探讨口咽通气管在脑卒中昏迷患者中应用的疗效。方法对80例Glasgow昏迷评分在3～8分的脑卒中患者,入院后清除呼吸道分泌物,放置口咽通气管,同时加强气道管理,观察呼吸及血氧饱和度等。结果 80例患者使用后通气功能迅速得到了改善,使用前呼吸频率为(30.00±2.16)次/min,血氧饱和度为(84.95±3.77)%,使用30 min后呼吸频率为(19.59±1.56)次/min,血氧饱和度为(97.85±0.93)%,使用前后比较差异有显著性(P<0.01)。结论脑卒中昏迷患者使用口咽通气管可以保持气道通畅,缓解缺氧症状,同时有利于吸痰及口腔护理等操作,是一种操作简便、经济、安全、有效的方法,可普遍推广使用。     

Ventilatory responses to exercise and to carbon dioxide in mitral stenosis before and after valvulotomy: causes of tachypnoea

1. The ventilation and cardiac frequency during progressive exercise and the respiratory responses to breathing carbon dioxide have been measured in 33 female patients with mitral stenosis and in 31 control subjects. Compared with the control subjects, the patients' exercise ventilation and cardiac frequency were increased; the exercise tidal volume at standard minute volume, the vital capacity and the ventilatory response to carbon dioxide were reduced. The extent to which the standardized tidal volume was lower during exercise than during breathing carbon dioxide was correlated with the severity of the stenosis, as gauged by the increase in exercise cardiac frequency above the level predicted from anthropometric measurements. 2. Twenty patients were studied postoperatively. In the 12 who showed clinical improvement the exercise ventilation and cardiac frequency were reduced and the exercise tidal volume at a given minute ventilation was increased. The latter change occurred despite a reduction in vital capacity, which was probably a residual effect of thoractomy. There was no significant change in the response to breathing carbon dioxide. No material change in function was observed in the patients whose condition was not improved by the operation. 3. It is suggested that in mitral stenosis the tachypnoea which occurs during exercise, whilst mainly a mechanical consequence of the reduced vital capacity, is also partly due to pulmonary congestion stimulating intrapulmonary receptors.     

Incidence of pulmonary barotrauma in a medical ICU

One hundred seventy-one patients admitted to a Medical ICU and who received treatment for respiratory failure with mechanical ventilation were studied for the development of pulmonary barotrauma (PBT) as manifested by pneumomediastinum, subcutaneous emphysema, or pneumothorax. Fourteen patients (8%; group A) developed this complication; they were younger, had higher maximal peak inspiratory airway pressures (PIP); and higher levels of maximal PEEP. We conclude that for medical patients treated for respiratory failure with mechanical ventilation, the incidence of PBT is 8% and that younger age, higher levels of PIP and PEEP seem to pose an increased risk for developing PBT.     

六分钟步行试验与摄氧量的相关性研究

背景:6 min步行试验是一种亚极量水平的运动试验,其操作简便、费用低廉,因而应用较广泛,然而将步行距离转换为最大运动能力是不易的.目的:课题组创新性地在6 min步行实验中引入做功的概念,将无线遥测呼吸气体分析仪同时应用于6 min步行试验和心肺运动试验,分析6 min步行试验中的距离、做功与峰值摄氧量与Bruce方案测得的最大摄氧量之间的相关性.设计、时间及地点:实验于2009-03/05在南京东南大学附属中大医院康复医学科完成.对象:健康受试者来自在中大医院康复医学科实习的学生,共25名,男14名,女11名;年龄(22.0±2.3)岁.方法:25名志愿者先按Bruce方案进行极量心肺运动试验,检测每位受试者极量运动时的最大摄氧量和无氧阈,再接受6 min步行试验,测量每位受试者的6 min步行距离、做功和峰值摄氧量.心肺运动试验和6 min步行试验均采用便携式K4b~2气体分析仪实时检测气体交换参数,以获得最大摄氧量和峰值摄氧量.主要观察指标:①摄氧量、心率、呼吸频率随时间的变化规律.②步行距离、做功、摄氧量、心率、呼吸频率的前后比较.③心肺运动试验中的最大摄氧量、无氧阈与6 min步行试验中的峰值摄氧量比较.④距离、做功与峰值摄氧量、最大摄氧量之间的相关性.结果:心肺运动试验测得的无氧阈与6 min步行试验测得的峰值摄氧量之间差异无显著性意义(P > 0.05).6 min步行距离与峰值摄氧量和最大摄氧量均无明显相关;6 min步行做功与峰值摄氧量呈线性相关(r=0.779 7,P < 0.001);6 min步行做功与最大摄氧量亦呈线性相关(r=0.894 1,P < 0.001).结论:6 min步行试验是一种无氧阈水平的运动试验.6 min步行做功既可反映受试者亚极量运动的能力,也能反映受试者极量运动的能力.