Ventilatory mechanics and expiratory flow limitation during exercise in normal subjects

We have examined the interrelationships among transpulmonary pressure, flow, and volume during exhausting exercise in 10 normal adult males. Expiratory transpulmonary pressures during exercise were compared with flow-limiting pressures measured at rest by two techniques. In no case did pressures developed during exercise exceed to an appreciable extent the flow-limiting pressures. This indicates that, during near-maximal exercise, ventilation remains efficient as judged in terms of the pressure-volume relationships of the lung. The mechanical properties of the lung do not appear to limit ventilation during exhausting exercise in normal subjects. We could find no relationship between the magnitude of transpulmonary pressure and exercise limitation. There was no evidence that lung mechanics changed during exhausting exercise in normal subjects. The two methods for estimating expiratory flow-limiting pressures, the orifice technique and the isovolume pressure-flow method, gave similar results.     

影响正常人和心肌梗塞患者等长收缩运动心血管反应的主要因素

对正常青年和中老年人，以及心肌梗塞患者进行观察，从 多方面综合评价影响等长收缩心血管反应的因素，论证了影响正常人和心肌梗塞患者心率，血压和心肌耗氧反应的基本特征和影响因素，从而为心血管患者日常生活活动和运动锻炼时处理等长收缩性活动提供指导。     

Respiratory and cardiovascular responses to manual chest percussion in normal subjects

The respiratory and cardiovascular responses to manual chest percussion were studied in seven naive healthy subjects. Percussion during quiet breathing, percussion with thoracic expansion exercises (TEE) and TEE alone were applied to subjects in side-lying. Inspired volume, oxygen consumption, oxygen saturation, heart rate and blood pressure were measured before, during and after each technique. Significant increases in inspired volume and heart rate occurred with all three techniques (p < 0.01). Oxygen consumption increased with all three techniques however only the increases during percussion with TEE, and TEE alone were significant (p < 0.01). Oxygen saturation increased with percussion with TEE and TEE alone (p < 0.01). No significant changes in blood pressure were observed.     

Transversus abdominis: Changes in thickness during the unsupported upper limb exercise test in older adults

Novel, short-lived upper limb tasks performed by young adults have been used to investigate the role of transversus abdominis (TrA) in maintaining postural stability. Little information exists concerning the behaviour of TrA in older adults during protracted postural challenges. The primary aim of this study was to describe the change in thickness of TrA during an incremental upper limb exercise test in older adults. A secondary analysis was undertaken to compare the results between younger and older subjects. Healthy subjects aged between 40 and 70 years performed the Unsupported Upper Limb Exercise Test (UULEX) while activity of TrA was continuously monitored by using rehabilitative ultrasound imaging. Changes in muscle dimensions were measured every minute during the test. The thickness of TrA increased significantly and exponentially between minutes 8 and 13 of the UULEX. Although there was a significant difference between older and younger subjects in absolute measures of TrA thickness, the change in TrA thickness as a percentage of resting thickness during the UULEX demonstrated an identical pattern between younger and older subjects. This study suggests that TrA is continually and increasingly active during an upper limb task in both younger and older asymptomatic subjects.     

Dopaminergic influence on cardiovascular responses to exercise stress in hypertensive subjects.

Ten hypertensive subjects were studied at the Vargas Medical School in Caracas, Venezuela. They were submitted to submaximal treadmill exercises according to Bruce's protocol under treatment with dopaminergic drugs (metoclopramide, bromocriptine). Before and during submaximal exercises, metoclopramide caused a hypotensive effect accompanied by an increased heart rate, which was blocked by the administration of bromocriptine. We conclude that a probable dopaminergic modulatory influence takes place during exercise.     

Effects of hyperinsulinaemia on the cardiovascular responses to graded hypovolaemia in normal and diabetic subjects

1. Two experiments were carried out. The first with five normal male subjects was placebo controlled and single blind, each subject being studied on two occasions. Lower body subatmospheric pressure (LBSP) was used to assess the cardiovascular effects of graded hypovolaemia before and during either a hyperinsulinaemic, euglycaemic clamp or a placebo clamp using 0.9% (w/v) NaCl only. 2. During hyperinsulinaemia, resting systolic blood pressure rose and was accompanied by forearm vasodilatation. Forearm blood flow (FABF) and heart rate (HR) were higher at each level of LBSP during than before hyperinsulinaemia. In addition, hyperinsulinaemia was accompanied by a small increase in noradrenaline, but packed cell volume did not change. 3. In the second experiment, the effects of a hyperinsulinaemic euglycaemic clamp on the cardiovascular responses to LBSP were assessed in seven diabetic subjects with peripheral and autonomic neuropathy. 4. In contrast to the normal subjects, there was a slight fall in systolic blood pressure during the clamp but no effect was noted on HR or FABF. Mean arterial blood pressure was lower at each level of LBSP during hyperinsulinaemia compared with the pre-clamp period. Packed cell volume fell during the clamp and plasma noradrenaline rose. In one of the diabetic subjects, a precipitous fall in blood pressure occurred during hyperinsulinaemia when LBSP of 10 mmHg (1.3 kPa) was applied, this manoeuvre having been well tolerated before the clamp. 5. The mode of action of hyperinsulinaemia is not clear, but there was, however, no evidence that a fall in plasma volume had occurred.     

Postinversion responses to inversion in normal subjects

The purpose of this study was to determine cardiac output and related cardiovascular responses during postinversion by comparing preinversion (baseline data) to postinversion data in healthy, normal subjects. Each of 20 subjects (means = 22 years) was inverted for five minutes. Cardiac output was measured noninvasively with the Beckman MMC and CO2 rebreathing program. ANOVA with repeated measures was used to determine significance of change between preinversion and postinversion values. The alpha level was set at 0.05 for statistical significance. During postinversion stand, there were (a) significant decreases in oxygen uptake (p less than 0.0008), cardiac output (p less than 0.0005), and stroke volume (p less than 0.0018); (b) significant increases in arteriovenous oxygen difference (p less than 0.0281), peripheral vascular resistance (p less than 0.0001), and diastolic blood pressure (p less than 0.0087); and (c) nonsignificant changes in heart rate, systolic blood pressure, and double product from the preinversion baseline standing position. The results demonstrate little if any need for concern for a subject's return to the upright position.     

Ventilatory responses to inhaled carbon dioxide at rest and during exercise in man

1. Rapid steady-state CO2 responses were determined in six normal subjects at rest and five subjects at four different work loads up to 125 W, by injecting pure CO2 at constant flow into a small mixing chamber in the inspiratory limb of a breathing circuit. 2. The time course of the response of ventilation (V) and mean alveolar PCO2 (PACO2) was checked in separate experiments, where the flow rate of injected CO2 was changed abruptly and the effects were followed for 10 min. 3. V and PACO2 were measured every breath, and the results ensemble-averaged for each subject (two or three runs per subject) and then for the groups as a whole, in 30 s or 60 s time bins. 4. PACO2 during exercise was estimated by graphical reconstruction from the sloping alveolar plateau, and separately by the empirical equation of Jones, Robertson & Kane [1]. At rest, PACO2 was assumed equal to end-tidal PCO2 (PetCO2). 5. With the constant inflow technique, 4 min was required to reach steady-state V and PACO2 during exercise, and 6 min at rest. 6. At rest, with 4 min steps (doubtful steady state) the averaged CO2 response was concave up. With 6 min steps the response was almost linear. In neither case was the deviation from linearity statistically significant. 7. During exercise, the averaged CO2 responses were essentially isocapnic at work loads greater than 75 W with either method of deriving PACO2.     

Reliability of upper limb tension test 1 in normal subjects and patients with carpal tunnel syndrome

Background and objective: Tension tests or neurodynamic techniques assess the mobility of the peripheral nerves and provide a guide for planning and managing physiotherapy treatments of entrapment syndromes such as carpal tunnel syndrome (CTS). One of the upper limb tension tests (ULTT) is ULTT1 that evaluates the efficacy of physiotherapy treatment. It has been shown to be a valid test but its reliability has not been investigated for CTS. Therefore, it is not known if the ULTT1 helps in diagnosing CTS and assessing CTS treatments. The purpose of this study was to determine the reliability of the ULTT1 in CTS.Material and methods: In order to determine the reliability of the ULTT1, we tested 23 healthy subjects and 12 subjects with CTS on two separate test days. Outcome measure for this study was elbow extension. Results: Inter subject elbow extensions were not significantly different between the two test days. Also, the coefficient of correlation ± SEM in healthy and CTS subjects were 0.89 ± 1.23 degrees and 0.84 ± 3.67 degrees, respectively. Conclusion: From the above results, we conclude that the ULTT1 is highly reliable and can be used in diagnosis as well as the management of CTS.     

Dynamic responses to intravenous urapidil and dihydralazine in normal subjects

Hemodynamic responses after urapidil were compared with those after dihydralazine in placebo-controlled, double-blind studies after cumulative intravenous doses. We recorded heart rate, blood pressure, systolic time intervals corrected for heart rate (electromechanical systole and preejection period), electrical impedance cardiography [(dZ/dt)/RZ index and mean electrical thorax impedance], and M-mode echocardiogram (end-systolic and -diastolic diameters, end-systolic wall stress, fractional shortening, and cardiac output). Both drugs induced dose-dependent reductions in total peripheral resistance, which resulted in reduction in left ventricular end-systolic wall stress and increases in heart rate (limited at +10 bpm with urapidil), fractional shortening, cardiac output, and the (dZ/dt)/RZ index. With each drug, diastolic blood pressure fell by 5 mm Hg, the corrected preejection period shortened (dihydralazine greater than urapidil), the corrected electromechanical systole did not change, and mean electrical thorax impedance rose with urapidil. The spectrum of effects indicates that both drugs reduce left ventricular afterload, thereby increasing left ventricular pump performance. Urapidil also exerts some preload reduction.     

上肢抗阻运动预防PICC相关性血栓的研究进展

本文对上肢抗阻运动预防PICC相关性血栓的影响机制及常见的上肢抗阻运动分类、方式、频率及强度进行综述,并指出现阶段研究存在的问题和未来研究方向,为临床工作者在预防PICC血栓的方案选择及最佳运动方式构建上提供参考和借鉴.     

Cardiovascular responses to low-intensity isometric handgrip exercise in coronary artery disease: effects of posture

BackgroundCoronary artery disease (CAD) lead to cardiovascular autonomic control disfunctions that can worsen exercise and/or posture adjustments.ObjectivesTo verify the cardiovascular responses to low-intensity isometric handgrip exercise performed in different postures in CAD patients. This study tested the hypothesis that the posture influences the cardiovascular responses during isometric handgrip exercise and that the presence of CAD leads to greater cardiovascular stress during this type of exercise.MethodsWe investigated cardiovascular responses to isometric handgrip exercise in 15 CAD patients (CADG) and 15 health matched-control (CG). The subjects performed isometric handgrip exercise at 30% of maximum voluntary contraction until exhaustion in SUPINE, SITTING and STANDING positions. Systolic arterial pressure, diastolic arterial pressure, mean blood pressure, heart rate, peripheral vascular resistance, cardiac output, stroke volume and double product were measured during rest (baseline), exercise (peak value) and recovery in the 1st minute (REC1). Delta PB (ΔPB, peak minus baseline) and PR1 (ΔPR1, peak minus REC1) were calculated.ResultsHigher ΔPB and ΔPR1 of systolic and mean arterial pressure and double product were observed in STANDING when compared to SITTING and/or SUPINE. CADG showed higher ΔPB of systolic and mean arterial pressure in all postures and higher ΔPR1 of strove volume in the SITTING.ConclusionWe concluded that the posture during isometric handgrip exercise influences the cardiovascular responses with STANDING leading to higher cardiovascular stress. CAD promoted higher arterial pressure responses however these responses were physiological and expected due to the presence of disease and type of exercise.     

上肢康复操在维持性血液透析患者中的应用研究

目的 评价上肢康复操在维持性血液透析患者中的应用效果。 方法 选取2021年10月—12月于山东省某三级甲等医院血液净化中心行维持性血液透析治疗的患者77例,按随机数字表分为试验组38例和对照组39例,试验组在常规护理的基础上进行上肢康复操训练,对照组只接受常规护理。分别比较干预前和干预3个月后两组的双手握力、肩关节活动度、动静脉内瘘血流量及非内瘘侧头静脉直径。 结果 试验组36例、对照组38例完成研究。干预前两组双手握力、肩关节活动度、动静脉内瘘血流量及非内瘘侧头静脉直径比较,差异无统计学意义（P>0.05）;干预后试验组与对照组比较,内瘘侧握力（t=-2.350,P=0.022）、非内瘘侧握力（t=-3.693,P<0.001）,内瘘侧肩关节外展（t=-2.468,P=0.016）、外旋（t=-5.167,P<0.001）、内旋（t=-2.059,P=0.043）,动静脉内瘘血流量（t=-2.020,P=0.047）、非内瘘侧头静脉直径（t=-5.229,P<0.001）均增加,差异具有统计学意义。 结论 上肢康复操训练有助于改善维持性血液透析患者的上肢功能及维护动静脉内瘘。     

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.     

Pain and muscular responses to a neural tissue provocation test in the upper limb

Pain and muscular responses to a Neural Tissue Provocation Test with bias to median nerve were examined in 20 asymptomatic subjects. The test was performed on both arms with the cervical spine in a neutral position and in contralateral sideflexion as a sensitizing manoeuvre. The angle of elbow extension at the time of onset of pain and muscle activity in trapezius, biceps and triceps muscles was measured using an electrogoniometer. Muscle activity was recorded by surface electromyography. Results indicate that pain responses and muscle activity of trapezius are present in the majority of normal subjects. The onset of pain was highly reliable and compared favourably with detection of muscle activity onset. There was no significant difference of the angle of the elbow with the onset of pain between arms. Hence in patients with unilateral neck or upper limb pain a difference between sides might be indicative of a possible neural tissue involvement.Pain and muscular responses were influenced by the position of the cervical spine. This finding suggests that cervical contralateral sideflexion has a sensitizing effect on neural tissues. There was an association between the onset of pain and onset of trapezius muscle activity in all painful trials. However, muscle activity was also present in subjects with no pain.