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Effect of increased lung volume on perception of breathlessness, effort, and tension.

By the addition of externally added elastic loads at both functional residual capacity (FRC) and increased lung volume, increased respiratory muscle effort, tension, and breathlessness were induced in normal subjects. The magnitude of each of these sensations was estimated using the psychophysical technique of category scaling (Med. Sci. Sports Exercise 14: 377-381, 1982). The tidal volume, inspiratory time, and breathing frequency were kept constant to avoid variability in sensation due to these factors. The perceived magnitude of effort and breathlessness increased significantly as the inspiratory pressure and lung volume increased (P less than 0.05). The magnitude of perceived tension increased as the inspiratory pressure increased (P less than 0.05) but not as lung volume increased. To validate these results, the subjects estimated the perceived magnitude of a series of static inspiratory occlusion pressures at both lung volumes using open-magnitude scaling and sensory matching. The perceived magnitude of effort increased significantly as the pressure increased and as the lung volume increased (P less than 0.05). To match the perceived effort required to produce the target pressures at FRC, the subjects reproduced pressures. These were not significantly different. However, to match the effort required to produce the target pressures at increased lung volume, the pressures reproduced at FRC were significantly greater (P less than 0.05). The results suggest that the sensations of breathlessness and effort are psychophysically the same, whereas tension is perceived by a different sensory mechanism.

Adult↗

The sensation of respiratory muscle force.

The sensation of respiratory muscle force was examined in 8 normal subjects using the direct scaling method of magnitude production. At the end of a normal expiration, at functional residual capacity (FRC), subjects generated an inspiratory effort against a closed airway to produce a force that correspond to specific numerical values for sensation magnitude. Thereafter, at lung volumes of 2 L above FRC and 1 L below FRC, subjects attempted to reproduce the same force as that previously generated at FRC. Diaphragm electromyographic activity, recorded with an esophageal electrode, was used as a measure of central respiratory motor output. The difference between the mouth pressure during relaxation against a closed shutter and the peak airway pressure during the static inspiratory maneuver (Pmus) was employed as an index of muscle tension. The exponent for the magnitude production of force during maneuvers at FRC, i.e., the slope of the line relating log airway pressure and log sensation magnitude was 1.60 +/- SE 0.15. The exponent for force scaling was 1.47 +/- SE 0.17 after correcting for differences in inspiratory duration during maneuvers of different force. During inspiratory maneuvers at FRC plus 2 L, diaphragm EMG was 441 +/- SE 70%, but Pmus was 111 +/- SE 11% of the respective values during subjectively equal efforts at FRC. During inspiratory maneuvers at FRC minus 1 L, diaphragm EMG was 54 +/- SE 5%, but Pmus was 94 +/- SE 4% of the respective values during efforts at FRC perceived to be of equal force. These results suggest that the sensation of respiratory muscle force depends primarily on signals related to the tension generated by the contracting muscles rather than on the sensation of innervation associated with the central nervous system motor command.

Adult↗

Scapulothoracic muscle fatigue associated with alterations in scapulohumeral rhythm kinematics during maximum resistive shoulder elevation.

Clinical examinations and biomechanical analysis of the shoulder often include an assessment of the scapulohumeral rhythm. It is important to understand factors which may affect the scapulohumeral rhythm so that optimal diagnostic and therapeutic strategies can be devised. The purpose of this study was to determine if the scapulohumeral rhythm, when assessed under dynamic conditions, is altered as a result of a fatigue-inducing exercise. Twenty-five subjects were required to elevate their arm against maximum resistance until they were no longer able to completely elevate their arm. Three-dimensional kinematics were measured using an electromagnetic tracking system. Electromyographic activity was recorded from the upper trapezius, lower trapezius, serratus anterior, and the middle deltoid muscles. Power frequency spectrum using the Fast Fourier Transform and the root mean square signal amplitudes were determined for each muscle. The scapulohumeral rhythm was determined using least squares regressions of humeral elevation to scapular upward rotation for 20% intervals (phases) of elevation for each subject. The results showed that during the midrange of elevation to maximum elevation [phases 3-5 (60-150 degrees)], the scapulohumeral rhythm decreased with fatigue, and that the decrease in the scapulohumeral rhythm was associated with myoelectric indicators of fatigue (median power frequency). The study suggests that shoulder fatigue affects the way in which the scapula moves concomitantly with the humerus. Fatigue tends to result in increased motion of the scapula, which alters the scapulohumeral rhythm.

Adolescent↗

[A case of extraskeletal Ewing's sarcoma of the thoracic wall].

The Authors report a case of extraskeletal Ewing's sarcoma of thoracic wall in a 15-year-old sport-man, who complained about pain in the left upper extremity. The diagnosis was performed by radiology (ultrasound study, TC, RM) and pre-operative needle-aspiration biopsy. The patient was treated by neoadjuvant chemotherapy, wide surgical resection and, then, radiotherapy. Neither local recurrence nor metastases have developed for 8 months.

Adolescent↗

[Ultrastructural changes in the skeletal muscles after physical exertion in rats of various ages].

The white rats of the age 1, 3 and 12 months ran in the treadmill at a speed 45 m/min for 20, 40, 60 and 90 days. There is not any linear dependence of muscular transformations and the intensity of physical loading. Changes of the material components of muscular fibers are of undulated character, depending on the age, increase in quantity of myofibrils is always accompanied with a decrease in the quantity of mitochondria. When the total share of myofibrils and mitochondria increases, the quantity of other ultrastructural elements of the muscular fibers and hyaloplasm decreases.

Age Factors↗

[The effect of atropine, fentanyl and alfentanyl on cardiocirculatory parameters and thoracic rigidity in the induction phase of intubation anesthesia].

Fentanyl and alfentanil may cause bradycardia if used in combination with succinylcholine during induction of anaesthesia. We therefore studied the influence of atropine, fentanyl and alfentanil on the haemodynamics of 90 urological patients (ASA I, II), who were allocated at random to six groups containing 15 patients each. Induction of anaesthesia was carried out using atropine 0.01 mg/kg-1, fentanyl 0.15 mg or alfentanil 1.5 mg depending on the assigned group: I atropine + fentanyl, II: atropine + alfentanil, III: fentanyl, IV: alfentanil, V: control (no atropine, no analgetic), VI: atropine. Following 2 mg alcuronium and thiopentone 4 mg/kg-1 intubation was performed with 2 mg/kg-1 succinylcholine. Atropine in combination with fentanyl caused a significant increase in heart rate following endotracheal intubation (p less than 0.05). Arrhythmias occurred in the groups with atropine in 4 out of 45 cases, while a chest wall rigidity was not influenced by atropine. Bradycardia occurred after fentanyl or alfentanil with atropine in the same frequency as without atropine. According to our results the routine use of atropine for induction of anaesthesia with thiopentone/fentanyl or alfentanil even in combination with succinylcholine is not required in ASA I or II patients.

Adult↗

Management of mammary subpectoral implant distortion.

Pectoral muscle flexion may impart an unpleasant distortionary appearance on the underlying mammary prosthesis. Surgical manipulation of the pectoral nerves and a change in the location of the mammary prosthesis are potential solutions to these problems.

Breast↗

[Paralysis of the serratus anterior muscle. Results of treatment of 12 cases including 9 surgically treated and a general review of the literature].

An analysis of the results of treatment in twelve cases of serratus anterior paralysis, nine of which were treated operatively, and a review of the literature has shown that, in lesions that fail with conservative treatment by physiotherapy, surgical treatment rapidly restores normal strength and function. Long follow-up, between 3 and 23 years, confirms the effectiveness and reliability of muscle transfers, particularly of pectoralis major.

Adolescent↗