Rate and force of application of manual chest percussion by physiotherapists

The rate and force of manual chest percussion as applied by 35 physiotherapists was investigated. The influence of gender, body weight, body mass index (BMI), rate and frequency of usage on force were examined. Percussion was applied to a healthy male for 35 seconds and the rate and force were measured using a force platform. The rate and force varied among subjects. The mean (SD) rate and force of percussion were 6.60 (1.00) Hertz and 58.10 (15.32) Newtons respectively. There was no relationship between force and 1) gender, 2) body weight, 3) BMI or 4) frequency of usage of percussion. A weak relationship was found between rate and force (r = -0.358, p = 0.034). Thirty-two subjects demonstrated a hand dominance.     

Ventilatory and cardiovascular responses to unsupported low-intensity upper limb exercise in normal subjects

The ventilatory and cardiovascular responses, and the rating of perceived exertion (RPE) to three types of unsupported low-intensity upper limb exercise (static, dynamic - unilateral and bilateral) were investigated in 22 normal subjects. A significant increase in tidal volume, respiratory rate, minute ventilation, oxygen consumption, carbon dioxide production and pulse rate occurred during all three exercises (p < 0.05). With the exception of tidal volume, these increases were significantly greater with dynamic exercise (p < 0.05). Local RPE was significantly higher than general RPE following both static and dynamic exercise (p < 0.05) with no significant differences between the three exercises. These findings provide some basis for the development of exercise protocols for testing in post-operative patients.     

Respiratory response to inversion in normal subjects

To evaluate the respiratory response to inversion, 20 young male athletes were suspended by their ankles in a vertical head-down position, while being monitored with ear oximetry and end-tidal CO2 nasal cannula. There was a decrease in O2 saturation (p less than 0.01), increase in end-tidal CO2 (p less than 0.01), and a decrease in respiratory rate (p less than 0.02). Spirometry was done in seven of these subjects, revealing decreases in forced vital capacity (5.7% +/- 2.0%), FEV1 (10.9% +/- 4.0%), FEF25-75 (13.3% +/- 7.4%), and peak expiratory flow rate (20.1% +/- 4.4%). Caution is advised in the use of inversion devices in patients with compromised cardiopulmonary service.     

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.     

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。     

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.     

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.     

Sweating responses of normal, paraplegic and anhidrotic subjects.

Dynamic sudomotor response to changing ambient temperatures (30 C to 45 C) was measured on eight unacclimatized subjects including five normals, two paraplegics and one anhidrotic patient. Mean sweating rates, computed from five simultaneously observed local rates, were used to compare the overall sudomotor response to heat exposure of the three groups. In the normal subjects, an average rise of 0.34 C in oral temperature and 2.5 C in mean skin temperature was found in a period of 65 minutes. The paraplegics developed a higher rise in both oral and skin temperatures due to a lower sweating rate in the insentinent region. (Insentient describes the sensory state of the skin below the level of the lesion where the subject has no awareness of surface stimulation). A relatively higher sweating rate was observed on the forehead and the cyclic sweating behavior of the insentient skin was not synchronous with that in the sentient. (Sentient describes the state where partial or total awareness is elicited by stimulation). The anhidrotic patient showed a twofold increase of moisture loss from the skin but no cyclic pattern of sweat gland activity on exposure to heat. In this case, hyperthermia developed with a rise in oral temperature of 1.1 C in 52 minutes versus 0.4 C rise in the controls in a period of 63 minutes.     

Effect of zolpidem during sleep on ventilation and cardiovascular variables in normal subjects

Summary— A double-blind study comparing the effect of zolpidem 10 mg, and placebo, on sleep architecture, nocturnal ventilation, cardiovascular parameters (heart rate, systolic, diastolic and mean blood pressures) was carried out. Ten healthy middle-aged males took part in the study. No significant differences were found between zolpidem and placebo in relation to sleep architecture. Mean respiratory disturbance index (RDI) and SaO₂ values (mean SaO₂, time spent with SaO₂ < 90%) were similar under both conditions. The diastolic and mean blood pressure readings taken from REM periods which occurred during the first third of the night were significantly higher with zolpidem. No changes in systolic blood pressure or heart rate were found with zolpidem in comparison to placebo.     

Psychological responses to episodic chest pain

Patients with chronic musculo-skeletal pain have been profiled as "dysfunctional", "interpersonally distressed" or "adaptive copers". The relevance of these for episodic visceral pain is unknown. Our aim was to replicate conceptually the taxonomy in patients with episodic visceral pain. Patients with chest pain and gastro-esophageal reflux disease (GERD; n=25), coronary artery (CAD; n=20), or with chest pain but without either reflux or coronary artery disease (non-cardiac chest pain--NCCP; n=23) were assessed using several standard affective and cognitive measures relevant to pain. Differences between the diagnostic groups were explored. K-means cluster analysis broadly replicated the three groups found in previous research but the "interpersonally distressed" group had few members. An additional cluster analysis suggested a more parsimonious solution for the sample was a two-cluster one, which approximated to the "adaptive coper" and "dysfunctional" profiles. Membership of both the three- and two-cluster profiles was not associated with membership of specific diagnostic category.     

Renal, endocrine, and cardiovascular responses to bed rest in male subjects on a constant diet.

BACKGROUND: Exposure to actual and simulated microgravity induces cardiovascular deconditioning through a variety of factors. Although the mechanisms involved remain uncertain, one involves alterations in volume-regulating systems--the hypothesis being tested in this study. To maximize our ability to detect subtle changes in the volume-regulating systems, subjects were studied on a high-average salt intake to maximally suppress these systems basally. METHODS: Fourteen healthy male subjects underwent 14-day head-down tilt bed rest (HDTB) during which a constant 200 mEq sodium, 100 mEq potassium diet was maintained. Daily 24-hour urine collection was performed; plasma renin activity, serum aldosterone, plethysmography, and cardiovascular system identification were performed during a control period (pre-HDTB) and at the end of HDTB (end HDTB). RESULTS: Sodium excretion increased initially (pre-HDTB = 182.8 +/- 10.4 mEq/total volume; early HDTB = 236.4 +/- 13.0; p = .002) and then returned to baseline values. Potassium excretion increased 4 days after the initiation of HDTB and remained elevated thereafter (pre-HDTB = 82.2 +/- 2.4/total volume; mid- to late HDTB = 89.4 +/- 2.1; p = .02). Plasma renin activity increased significantly with HDTB (pre-HDTB = 1.28 +/- 0.21 ng/mL/h; end HDTB = 1.69 +/- 0.18; p = .01), but serum aldosterone did not change. A significant decrease in autonomic responsiveness and an increase in leg compliance were observed. CONCLUSIONS: We conclude that even in the presence of a high-average salt intake diet, simulated microgravity leads to renal, cardioendocrine, and cardiovascular system alterations that likely contribute to cardiovascular deconditioning.     

Effect of acute dose of caffeine on cardiovascular autonomic responses in healthy subjects

Summary. The effect of acute dose of caffeine (4 mg kg^-1) on cardiovascular autonomic responses were studied in 10 healthy subjects. Standard cardiovascular reflex tests were used during which heart rate and blood pressure were continuously measured. Each subject was tested twice in a random order, with and without prior use of caffeine. It was found that immediate heart rate responses following standing up were lower under influence of caffeine. Blood pressures were systematically, although non-significantly, higher and blood pressure responses in isometric handgrip test stronger when caffeine was used before testing. It is suggested that caffeine should not be used before autonomic testing. This is especially important when the test(s) are performed for research purposes or in order to study the blood pressure responses. If the tests are made for diagnostic purposes the following rules should be adopted: (1) if the subject has used caffeine before testing but all heart rate responses are within normal ranges, it can be assumed that the subject does not have cardiac parasympathetic neuropathy and retesting is not necessary; (2) if the patient has used caffeine before testing and the results suggest presence of autonomic neuropathy, the patient must be retested without the prior use of caffeine.     

Respiratory indices by gas analysis and fat metabolism by indirect calorimetry in normal subjects and triathletes

Background: The effects of exercise on different indices reflecting the metabolism have been of interest for a long time, and a relationship between anaerobic indices and maximal oxygen uptake has been established. The inter‐relationship between different respiratory indices during an exercise test remains to be studied in order to understand differences between individuals. Therefore, the aim of this study was to determine three respiratory indices and investigate their inter‐relationship in individuals with highly variable working capacity. A second aim was to investigate the fat metabolism at the VO₂ corresponding to the respiratory compensation point (Pq) in the different subjects using indirect calorimetry. Methods: Sixty control subjects (20 female) and 18 triathletes (six female) performed an exercise test with gas analysis. Three respiratory indices, derivative crossing (Dx), point of crossing (Px) and respiratory compensation point (Pq), were calculated using a computerized method. Fat metabolism at Pq was calculated using indirect calorimetry. Results: Two different sequences of the respiratory indices were found: Dx<Px<Pq and Dx<Pq<Px. In subjects whom Px occurred before Pq, no fat metabolism was seen at Pq, whilst in subjects with Pq occurring before Px, a combined aerobic fat metabolism and anaerobic carbohydrate metabolism was found at Pq. Conclusion: This study has shown two different sequences of the respiratory indices Dx, Px and Pq in subjects of varying working capacity. The individual differences in the order of occurrence of Px and Pq during the exercise test are most likely caused by different abilities to metabolize fat at high workloads.