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Biomedical subjects

M Gorini

Publications and source records attributed to M Gorini.

At least 73 records · Page 4Linked to original sources
PubMed1992

Control of breathing in patients with myasthenia gravis.

Control of breathing has seldom been investigated in patients with myasthenia gravis (MG). We evaluated lung volumes and respiratory muscle strength by measuring maximal inspiratory (MIP) and expiratory (MEP) pressures in 12 patients with moderate generalized (IIb) MG before and after an orally administered therapeutic dose (120 mg) of Mestinon, and in 11 age- and sex-matched normal subjects. Breathing pattern, mouth occlusion pressure (P0.1), and surface electromyographic activity of the diaphragm (EMGd) and intercostal (EMGint) muscles were evaluated during both room-air breathing and hypercapnic rebreathing. Before Mestinon, patients exhibited a slight decrease in VC, and normal TLC and FEV1/VC ratio. Compared with the normal control group, patients also exhibited respiratory muscle weakness (marked decrease in MIP and MEP; p less than 0.001 for both), and more rapid and shallower breathing (RSB): lower tidal volume (VT), inspiratory time (TI), expiratory time (TE), and greater respiratory frequency (f); mean inspiratory flow (VT/TI) and P0.1 were slightly supernormal, whereas both EMGd and EMGint were significantly higher in patients. During hypercapnic rebreathing, ventilation (VE) (p less than 0.001), VT (p less than 0.001), VT/TI, (p less than 0.003), P0.1 (p less than 0.003), and EMGd (p less than 0.001) response slopes to increasing PCO2 were found to be lower, whereas EMGint response slope was normal. At 60 mm Hg of PCO2 in the two groups the difference in terms of breathing pattern, P0.1, and EMGd were similar to that observed during room-air breathing. After Mestinon, VC (p less than 0.005), MIP (p less than 0.02), and MEP (p less than 0.01) significantly increased, whereas spontaneous breathing remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effect of head-up tilt on neural inspiratory drive in the anesthetized dog.

To examine how anesthetized dogs compensate for the diaphragmatic shortening that occurs during head-up tilting, we measured the electroneurogram (ENG) of the C5 phrenic root and the electromyographic (EMG) activity of the parasternal intercostal and transversus abdominis muscles in eight spontaneously breathing animals during postural changes between supine (0 degree) and 80 degrees head-up. Both steady state ENG and EMG activities and first breath responses to tilting from 80 degrees head-up to supine were studied. These experiments have shown that: (1) anesthetized dogs respond to head-up tilting by increasing the neural drive to the costal diaphragm and parasternal intercostals; (2) this response, however, does not occur on the first breath and therefore cannot compensate for the immediate changes in diaphragmatic length; (3) the abdominal muscles, in contrast, show a first breath response to tilting and their activation is primarily responsible for the maintenance of tidal volume. Unlike in humans, increases in neural inspiratory drive in head-up anesthetized dogs are mediated by a chemoreceptive, rather than proprioceptive, feedback mechanism.

Anesthesia↗
PubMed1991

Action of intercostal muscles on the lung in dogs.

The action on the lung of interosseous intercostal muscles located in the third and the seventh interspaces was studied in 15 anesthetized-curarized supine dogs. Changes in pleural pressure, airflow rate, and lung volume produced by maximal stimulation of both intercostal muscle layers were measured at and above functional residual capacity (FRC). In five animals measurements were also obtained during isolated stimulation of the internal layer. At FRC, intercostal stimulation in the upper interspaces had invariably an inspiratory effect on the lung but no effect was detectable in the lower interspaces. Qualitatively similar results were obtained during isolated stimulation of the internal layer. Increasing lung volume reduced the inspiratory action of the upper intercostals and conferred an expiratory action to the lower intercostals. These results indicate the following: 1) when contracting in a single interspace, the external and internal intercostals have a qualitatively similar action on the lung; and 2) this action, however, depends critically on their location along the cephalocaudal axis of the rib cage: in the upper portion of the rib cage, both muscle layers have an inspiratory effect at and above FRC; in the lower portion of the rib cage, they have no respiratory action at FRC and act in the expiratory direction at higher lung volumes.

Animals↗
PubMed1991

Control of breathing in patients with chronic pulmonary obstructive disease: response to bamiphylline.

In two groups (A and B) of patients with severe chronic obstructive pulmonary disease (COPD), matched for age and routine pulmonary function testing, we evaluated inspiratory muscle strength (MIP), breathing pattern, mouth occlusion pressure (P0.1), inspiratory neural drive, assessed in terms of electromyographic activity of both diaphragm (EMGd) and intercostal (EMGint) muscles, and P0.1/EMGd ratio, an index of inspiratory neuromuscular coupling. Group A (8 patients) was studied before and after a 7-day period of a new oral xanthine derivative (bamiphylline, 1.2 g daily), and group B (7 patients) was given a placebo. Under control conditions, compared with an age-matched normal control group, groups A and B both exhibited a decrease in MIP, more rapid (increase in respiratory frequency RF) and shallower (decrease in tidal volume; VT) breathing (RSB), a marked increase in both EMGd and EMGint and a lower P0.1/EMGd ratio. With bamiphylline FEV1 and PaO2 significantly increased, while a substantial increase in MIP was found in 5 out of the 8 patients. VT and inspiratory time (Ti) also significantly increased, and RF decreased. Both EMGd and EMGint significantly decreased, whereas P0.1/EMGd exhibited a substantial increase in 5 out of the 8 patients. Conversely, no significant changes were observed in group B during the study period. From these data we conclude that in patients with COPD, clinical manifestations, probably associated with inspiratory muscle overloading (decrease in muscle strength, RSB, increase in respiratory neural drive, and derangement in neuromuscular coupling) may benefit from a short-term treatment with bamiphylline.

Aged↗
PubMed1990

Transversus abdominis muscle function in humans.

We used a high-resolution ultrasound to make electrical recordings from the transversus abdominis muscle in humans. The behavior of this muscle was then compared with that of the external oblique and rectus abdominis in six normal subjects in the seated posture. During voluntary efforts such as expiration from functional residual capacity, speaking, expulsive maneuvers, and isovolume "belly-in" maneuvers, the transversus in general contracted together with the external oblique and the rectus abdominis. In contrast, during hyperoxic hypercapnia, all subjects had phasic expiratory activity in the transversus at ventilations between 10 and 18 l/min, well before activity could be recorded from either the external oblique or the rectus abdominis. Similarly, inspiratory elastic loading evoked transversus expiratory activity in all subjects but external oblique activity in only one subject and rectus abdominis activity in only two subjects. We thus conclude that in humans 1) the transversus abdominis is recruited preferentially to the superficial muscle layer of the abdominal wall during breathing and 2) the threshold for abdominal muscle recruitment during expiration is substantially lower than conventionally thought.

Abdominal Muscles↗
PubMed1990

Inspiratory muscle strength and respiratory drive in patients with rheumatoid arthritis.

In 15 patients with rheumatoid arthritis (RA) and in 12 age- and sex-matched normal subjects, we evaluated inspiratory muscle strength and respiratory control system. Inspiratory muscle strength was assessed by measuring maximal inspiratory pressure (MIP). Respiratory drive was assessed by evaluating surface electromyographic activity of the diaphragm (EMGd) during both room-air breathing and hypercapnic rebreathing. Compared to the predicted value (mean +/- 1.65 SD), MIP was significantly reduced in nine patients (60%). All told, we noticed a significant inverse relationship in the patients between MIP and duration of steroid therapy (p less than 0.01). During room-air breathing, both EMGd and mouth occlusion pressure (P0.1), expressed both in actual values and as percentage of MIP, were significantly greater in patients than in the normal control group (p less than 0.001 for both). Both EMGd and P0.1 (%MIP) response slopes to CO2 were significantly greater in patients than in the normal control group (p less than 0.01 and p less than 0.001, respectively) and significantly related to the functional stage of disease. During quiet breathing and for a PETCO2 of 60 mm Hg, both EMGd (p less than 0.01 and p less than 0.05, respectively) and P0.1 (%MIP) (p less than 0.01 and p = 0.001, respectively) were inversely related to MIP. These results indicate that RA patients may exhibit inspiratory muscle weakness and increased respiratory drive. Steroid myopathy and rheumatoid myositis could explain the reduction in MIP, whereas neural afferents arising from respiratory muscle, lung, or joint receptors could be involved in the observed increase in neural drive.

Arthritis, Rheumatoid↗
PubMed1990

Changes in ventilatory muscle function with negative pressure ventilation in patients with severe COPD.

Patients with severe COPD may be in a state of ventilatory muscle (VM) fatigue. In these patients, rapid and shallow breathing has been hypothesized to be a compensatory mechanism that prevents more severe fatigue from taking place. To test these hypotheses, we studied the effects of VM resting in a group of patients with severe COPD. Eleven clinically stable patients with COPD and chronic hypercapnia were studied. Six of them (group A) had a seven-day period of negative pressure-assisted ventilation (NPV), and five (group B) with similar functional characteristics served as a control group. Compared with a normal age-matched control group, both A and B groups exhibited significantly lower tidal volume (VT), inspiratory time (TI), total time of the respiratory cycle (Ttot) and Ti/Ttot ratio, decrease in muscle strength, and greater electromyographic activity of diaphragm (EMGd) and parasternal muscles, but similar ventilation and VT/TI. After the study period, group A exhibited significant increase in VT, Ti, and TI/Ttot (p less than 0.05), and decrease in PaCO2 (p less than 0.05), EMGd, and EMGint (p less than 0.05 for both), and a slight but significant increase in maximal inspiratory pressure (MIP) (p less than 0.05). These data suggest that NPV rests VM, increases their strength, and reduces hypercapnia in patients with severe COPD.

Aged↗
PubMed1990

Neural respiratory drive and neuromuscular coupling in patients with chronic obstructive pulmonary disease (COPD).

In 15 spontaneously breathing patients with chronic obstructive pulmonary disease (COPD) divided into two groups, one with normocapnia (A) and one with chronic hypercapnia (B), we evaluated the maximal voluntary inspiratory muscle strength (MIP), the pattern of breathing, the mouth occlusion pressure (Po.1), the neural respiratory drive (NRD), assessed by surface electromyographic (EMG) activity of the diaphragm (EMGd) and EMG activity of intercostal muscles (EMGint), and the chest wall neuromuscular coupling, assessed in terms of Po.1/EMGd ratio. Compared with an age-matched normal control group, both A and B groups exhibited lower MIP, significantly greater EMGd and EMGint, and lower Po.1/EMGd ratio. However, a similar pattern, along with a rapid and shallow breathing, differentiated group B from group A. In group B we found a significant direct relationship between Po.1/EMGd ratio and MIP, and an inverse relationship between PaCO2 and Po.1/EMGd ratio. These data seem to indicate the following: (1) EMG is a more precise method than Po.1 in assessing the magnitude of the NRD; (2) NRD is increased in these patients; and (3) clinical manifestations probably associated with inspiratory muscle fatigue (marked decrease in muscle strength, rapid and shallow breathing, and alveolar hypoventilation) may be accompanied by a greater NRD and a more marked derangement in chest wall neuromuscular coupling in COPD.

Aged↗
PubMed1989

Application of a WHO protocol on medical therapy for oncologic pain in an internal medicine hospital.

Pain symptomatology is present in 60% - 80% of patients affected by advanced cancer, but in most cases it is not adequately treated. Our series, composed of 45 patients affected by cancer in an advanced stage, demonstrates how the application of common concepts of pharmacotherapy, standardized according to a sequential scheme proposed by the WHO, makes it possible to reach total control (in 24.4% of our cases) or only slight residual persistence (in 68.8% of our cases) of pain from cancer, with scarce side effects that are easily controlled with symptomatic therapy. According to the type of pain, its behavior in relation to the therapy effected and any previous pharmacologic treatment, the proposed pharmacologic scheme foresees, as the first step, the use of non-narcotic drugs, eventually associated or substituted with weak narcotics or finally with strong narcotics. Attention is given to modulation of the administration, to guarantee an analgesic effect throughout the day, thus preventing the pain. Irrespective of the analgesic scheme employed, it is more effective if patients affected by chronic oncologic pain (who present an important emotional component) are treated contemporaneously with anxiolytic and antidepressive drugs and those in which nerve structures are involved are treated with steroids. In conclusion, pain of an oncologic patient in an advanced stage can almost always be alleviated or often eliminated by the rigorous application of therapeutic concepts well known by physicians but for various reasons often neglected in clinical practice.

Antidepressive Agents↗
PubMed1989

Control of breathing in patients with short-term primary hypothyroidism.

In 8 patients (3 men and 5 women) with short-term primary hypothyroidism before and during replacement therapy, and in an age-matched control group (9 men and 7 women), we assessed maximal inspiratory muscle force (Pimax) and the ventilatory control system at neural (EMG), muscular (P0.1), and ventilatory (VE and Vt/Ti) levels. While hypothyroid, patients exhibited a significantly lower Pimax. During a CO2 rebreathing test, hypothyroid patients exhibited similar diaphragmatic electromyographic (EMGd) and ventilatory (VE) response slopes to increasing end-tidal CO2 tension (delta EMGd/delta Pet CO2 and delta VE/delta PetCO2), but significantly less delta P0.1/delta PetCO2 (p less than 0.05) and delta(Vt/Ti)/delta PetCO2 (p less than 0.05) response slopes. During replacement therapy with L-triiodothyronine (L-T3), Pimax (p less than 0.05), delta P0.1/delta PetCO2, and delta(Vt/Ti)/delta PetCO2 response slopes were found to be significantly increased (p less than 0.05 for both) while neither EMGd nor VE response changed significantly. We concluded that short-term hypothyroidism does not seem to be associated with blunted neural inspiratory output (EMGd), the respiratory control system seems to be affected mostly at a peripheral (muscular) level, and L-T3 increases both force (P0.1 and Pimax) and velocity (Vt/Ti) of inspiratory muscle contraction.

Adult↗
PubMed1989

Neural respiratory drive and neuromuscular coupling during CO2 rebreathing in patients with chronic interstitial lung disease.

In 12 patients with CILD and 18 age-matched normal subjects we assessed the ventilatory control system at three levels: (a) neural, as assessed by EMGd (XP/Ti) and EMGint muscles via surface electrodes; (b) muscular, as assessed by mouth occlusion pressure (P0.1); and (c) ventilatory, as assessed by both ventilation (VE) and the related parameters, tidal volume (VT) and respiratory frequency (f). Compared with a normal control group, patients exhibited a significant decrease in lung volumes and in MIP; VT and inspiratory time (Ti) were significantly lower, while VT/Ti, P0.1, and both EMGd and EMGint were significantly greater in patients. During a CO2 rebreathing test, patients exhibited significantly greater EMGd, EMGint, and P0.1 responses to increasing PETCO2 than the control group. VE response slopes were similar in the two groups. For a given EMGd response slope (delta XP/Ti/delta PETCO2), the average P0.1 response slope (delta P0.1/delta PETCO2) was found to be significantly lower in patients than in the normal control group. Compared with normal subjects, CILD patients have a normal or increased neural component of respiratory activity and relatively low neuromuscular coupling (delta P0.1/delta XP/Ti). The decreased neuromuscular coupling could be explained in these patients by a reduced inspiratory muscle strength.

Aged↗
PubMed1988

Changes in neural drive (EMGd) and neuromuscular coupling during histamine-induced bronchoconstriction in patients with asthma.

This study was undertaken in order to assess the neural drive to the respiratory muscles and the inspiratory neuromuscular coupling in patients with bronchial asthma during histamine-induced bronchoconstriction. Bronchoconstriction was produced in a graded fashion, with histamine phosphate aerosol of increasing dose, in twelve asymptomatic asthmatic patients and was measured by FEV1. Inspiratory drive was measured by electromyographic activity of the diaphragm (EMGd) and the coupling of the neural drive to the respiratory muscles was assessed by the relationship of mouth occlusion pressure (P0.1) to EMGd. During the test we also measured electromyographic activity of the inspiratory intercostal (EMGint), sternomastoid (EMGsm) and expiratory abdominal (EMGab) muscles. Histamine caused a significant decrease in FEV1, a significant increase in P0.1, EMGd, EMGint, and a relevant increase in EMGsm, with no substantial increase in EMGab. An inverse significant relationship between the change in FEV1 and changes in P0.1, EMGd and EMGint and a significant correlation between the change in FEV1 and in the P0.1/EMGd ratio were observed. We conclude that a progressive increase in bronchospasm is accompanied by a progressive increase in respiratory neural drive and decrease in neuromuscular coupling. This could be caused both by an increase in lung volume and a lack of abdominal expiratory muscle recruitment.

Adult↗
PubMed1987

Effects of aminophylline on respiratory drive and neuromuscular coupling in normal man and in patients with chronic airflow obstruction.

In order to evaluate the separate effects of aminophylline on the neural and muscular components of the respiratory control system, assessed by electromyographic activity of the diaphragm (EMGd) and mouth occlusion pressure (P0.1), respectively, 6 normal subjects and 14 patients with mild or moderate chronic airflow obstruction (8 asthmatics and 6 COPD) were studied during CO2 rebreathing, before and after administration of a therapeutic dose of aminophylline 5.6 mg/kg. Compared to normal subjects, before aminophylline administration both asthmatic and COPD patients exhibited a significantly greater value in EMGd response slope to CO2. In no group did aminophylline modify P0.1 or EMGd activity response slope to CO2, nor did it significantly affect neuromuscular coupling, assessed by plotting change in P0.1 against change in EMGd activity with increasing CO2. The data appear to indicate that aminophylline in therapeutic concentrations does not modify respiratory drive or neuromuscular coupling in normal subjects, or in patients with mild or moderate chronic airflow obstruction.

Action Potentials↗
PubMed1987

Inspiratory impedance during histamine-induced bronchoconstriction in patients with bronchial asthma.

Histamine inhalation provocation tests were performed in 18 asymptomatic asthmatic patients with progressively increasing doses of a pressurized aerosol of histamine phosphate. Forced expiratory volume in 1 s (FEV1), total neuromuscular output, assessed by mouth occlusion pressure (P0.1), mean inspiratory flow (VT/Ti), and the P0.1/(VT/Ti) ratio, which represents an index of effective inspiratory impedance of the respiratory system, were measured. With histamine, compared to control, FEV1 decreased and P0.1/(VT/Ti) increased (p less than 0.01 for both). After bronchoconstriction was reversed by administration of a beta 2-agonist bronchodilator (fenoterol), a significant decrease in P0.1/(VT/Ti) (p less than 0.001) and a significant increase in FEV1 (p less than 0.01) were noted as compared to histamine. With histamine, change in P0.1/(VT/Ti) was found to be related to its pre-histamine value (p less than 0.01). Furthermore, with histamine and fenoterol, changes in P0.1/(VT/Ti) and concurrent changes in FEV1 were found to be significantly related (p less than 0.001). From these data we calculated that the P0.1/(VT/Ti) ratio provides a useful tool in the clinical assessment of histamine-induced bronchospasm.

Adult↗