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Biomedical subjects

A Pesenti

Publications and source records attributed to A Pesenti.

At least 37 records · Page 2Linked to original sources
PubMed2001

Limb immobilization for the treatment of focal occupational dystonia.

BACKGROUND: Occupational focal upper-limb dystonia is characterized by involuntary muscle contractions that selectively interfere with the execution of specific motor tasks such as writing or playing a musical instrument. Occupational dystonias have a severe social impact, especially in certain professions. The available medical treatments offer little benefit. METHODS: In eight patients with idiopathic occupational focal dystonia of the upper limb, the dystonic forearm and hand were immobilized with a plastic splint for mean (+/-SD) 4.5 +/- 0.75 weeks. Before splinting (base line) and at various intervals afterwards (4, 12, and 24 weeks), the authors assessed the severity of dystonia and the patients' motor performance objectively (Arm Dystonia Disability Scale and Tubiana and Chamagne Score) and subjectively (Self-Rating Score). RESULTS: Assessment 4 weeks after splint removal, when patients had regained normal voluntary movements, showed that the severity of dystonia and the patients' performance of the impaired motor task had improved; the benefit persisted unchanged at later follow-up visits (Arm Dystonia Disability Scale: base line 20.6 +/- 30.2%; after 4 weeks 83.9 +/- 23.8%, p = 0.007; after 12 weeks 83.9 +/- 23.8%, p = 0.007; after 24 weeks 79.7 +/- 29.5%, p = 0.015. Tubiana and Chamagne Score: base line 28.6 +/- 22.7%; after 4 weeks 80.0 +/- 23.1%, p = 0.015; after 12 weeks 80.0 +/- 23.1%, p = 0.015; after 24 weeks 74.3 +/- 32.1%, p = 0.031. Self-Rating Score: base line 20.6 +/- 19.3%; after 4 weeks 63.7 +/- 25.2%, p = 0.015; after 12 weeks 66.9 +/- 28.1%, p = 0.015; after 24 weeks 70.6 +/- 31.8%, p = 0.015). At the 24-week visit the improvement disappeared in one patient, was moderate in three, and marked in four. CONCLUSIONS: Limb immobilization can be a simple, effective, safe, and inexpensive treatment for focal occupational upper-limb dystonia.

Adult↗
PubMed2001

Transient improvement induced by motor fatigue in focal occupational dystonia: the handgrip test.

Muscle fatigue induced by a previous sustained contraction temporarily decreases the motor output, transiently worsening motor performance. Whether muscle fatigue alters motor performance also in dystonia-a disorder whose main pathophysiological abnormality is motor overflow-remains unknown. To assess the effects of muscle fatigue in patients with focal occupational upper limb dystonia, we studied the effect of a previous maximum fatiguing voluntary contraction on motor performance in 10 musicians with focal occupational dystonia, in 3 musicians with hand motor impairment due to non-dystonic disorders, and in 5 normal musicians. The fatiguing task consisted of grasping a spring handgrip as long as possible until the task failed. In dystonic musicians, a fatiguing contraction significantly improved motor performance. The improvement lasted less than 5 minutes and appeared only after fatigue of the affected upper limb. In contrast, in musicians with non-dystonic motor impairment, motor performance remained unchanged or worsened, and normal musician performance consistently worsened.

Adult↗
PubMed2001

Computerised tomography scan imaging in acute respiratory distress syndrome.

Computerised tomography (CT) is being used with increasing frequency in acute respiratory distress syndrome (ARDS) patients. This brief review will discuss some of the clinical insights that a CT scan can offer. A large number of CT scan studies have provided new insights into the pathophysiology of ARDS and of mechanical ventilation, and are particularly focused on the recruitment-derecruitment phenomenon. To this end, newer fast CT scan technology promises a dynamic, rather than a static view of lung ventilation.

Adult↗
PubMed2001

Closed system endotracheal suctioning maintains lung volume during volume-controlled mechanical ventilation.

OBJECTIVE: A closed suction system (CS) maintains connection with the mechanical ventilator during tracheal suctioning and is claimed to limit loss in lung volume and oxygenation. We compared changes in lung volume, oxygenation, airway pressure and hemodynamics during endotracheal suctioning performed with CS and with an open suction system (OS). DESIGN: Prospective, randomized study. SETTING: Intensive care unit in a university hospital. PATIENTS: We enrolled ten patients, volume-controlled (VC) ventilated with a Siemens Servo 900 ventilator (PaO2/FIO2 192 +/- 70, PEEP 10.7 +/- 3.9 cmH2O). INTERVENTIONS: We performed four consecutive tracheal suction maneuvers, two with CS and two with OS, at 20-min intervals. During the suction maneuvers continuous suction was applied for 20 s. MEASUREMENTS AND MAIN RESULTS: We measured end-expiratory lung volume changes (delta VL), tidal volume (VTrt), respiratory rate (RR) and minute volume (VErt) by respiratory inductive plethysmography; arterial oxygen saturation (SpO2), airway pressure and arterial pressure (PA). Loss in lung volume during OS (delta VL 1.2 +/- 0.7 l) was significantly higher than during CS (delta VL 0.14 +/- 0.1 l). During OS we observed a marked drop in SpO2, while during CS the change was only minor. During CS ventilation was not interrupted and we observed an immediate increase in RR (due to the activation of the ventilator's trigger), while VTrt decreased, VErt was maintained. CONCLUSIONS: Avoiding suction-related lung volume loss can be helpful in patients with an increased tendency to alveolar collapse; CS allows suctioning while avoiding dramatic drops in lung volumes and seems to be safe during the VC ventilation setting that we used.

Adult↗
PubMed2001

Non-motor effects of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: preliminary physiological results.

Although deep brain stimulation (DBS) is a clinically effective therapy for patients with advanced Parkinson's disease (PD), its physiological effects on the brain and possible actions on non-motor functional systems remain largely unknown. This study evaluated the effects of DBS of the subthalamic nucleus (STN) on neurophysiological variables and on cardiovascular physiology. Nine patients affected by PD undergoing chronic DBS of the STN have been studied. We performed electroencephalography (EEG), somatosensory (SEPs) and visual evoked potentials (VEPs), exteroceptive masseteric silent period and sympathetic skin response (SSR) studies with DBS ON and OFF. To assess the effects of stimulation on the cardiovascular system the tilt test and plasma renin activity were studied. When we turned the DBS OFF, both SEP N20 and the VEP P100 component increased significantly in amplitude whereas the SSR decreased in amplitude and increased in latency. Although plasma renin activity tended to increase with DBS OFF, its modification induced by postural changes and blood pressure values did not significantly differ with DBS ON and OFF. We conclude that DBS of the STN in PD, besides inducing a clinical improvement, induces several non-motor effects.

Afferent Pathways↗
PubMed2001

Decreased EMG inhibition following electrical stimulation over muscle tendons in myopathies.

OBJECTIVE: To assess the central EMG inhibitory action of tendon afferent input in muscle diseases. METHODS: The EMG inhibition elicited by electrical stimulation over muscle tendons was tested in 13 healthy voluntary subjects and 8 patients who had a primary muscle disease with a mild force deficit. Electrical stimuli were delivered to the tendon of the extensor carpi radialis muscle at the wrist during tonic voluntary isometric contraction at 50% of the maximum EMG level. The EMG signal was recorded by surface electrodes over the extensor carpi radialis muscle. RESULTS: The prestimulus background EMG level was reduced in 7 out 8 of the patients. Both groups had the same phases of EMG modulation following tendon stimulation (TE1, TI1, TE2) and their latency and amplitude did not differ significantly. Conversely, the area of TI1 was significantly larger (i.e. the inhibition decreased) in patients ([mean+/-SD] absolute area: controls=4.1+/-1.6 mVms, patients=6.9+/-2.9 mVms, P<0.05). CONCLUSIONS: In muscle dysfunction there are serial 'upstream' changes of central inhibitory systems, probably to maximize the residual muscle power of the affected muscle.

Adolescent↗
PubMed2001

Induced abdominal compartment syndrome increases intracranial pressure in neurotrauma patients: a prospective study.

OBJECTIVE: To evaluate the effect of a stepwise increase in intra-abdominal pressure (IAP) on intracranial pressure (ICP) and to further define the pressure transmission characteristics of different body compartments. DESIGN: A prospective, nonrandomized study. SETTING: A multidisciplinary intensive care unit at a university medical center. PATIENTS: Fifteen patients with moderate-to-severe head injury. INTERVENTIONS: All patients were studied after the initial stabilization and resolution of intracranial hypertension. Measurements were carried out before and 20 mins after IAP was increased by positioning a soft, 15-L water bag on the patient's abdomen. MEASUREMENTS AND MAIN RESULTS: Placing weights upon the abdomen generated a significant increase in IAP, which rose from 4.7 +/- 2.9 to 15.5 +/- 4.1 mm Hg (p <.001). The rise in IAP caused concomitant and rapid increases in central venous pressure (from 6.2 +/- 2.4 to 10.4 +/- 2.9 mm Hg; p <.001), internal jugular pressure (from 11.9 +/- 3.2 to 14.3 +/- 2.4 mm Hg; p <.001), and ICP (from 12.0 +/- 4.2 to 15.5 +/- 4.4 mm Hg; p <.001). Thoracic transmural pressure, calculated as the difference between central venous pressure and esophageal pressure, remained constant during the protocol. Respiratory system compliance decreased from 58.9 +/- 9.8 to 44.9 +/- 9.4 mL/cm H2O (p <.001) in all patients because of decreased chest wall compliance. The mean arterial pressure increased from 94 +/- 11 to 100 +/- 13 mm Hg (p <.01), which allowed the maintenance of a stable cerebral perfusion pressure (82.4 +/- 10.3 vs. 84.7 +/- 11.5 mm Hg; p = NS) despite the ICP increase. CONCLUSIONS: Increased IAP causes a significant rise in ICP in head trauma patients. This effect seems to be the result of an increase in intrathoracic pressure, which causes a functional obstruction to cerebral venous outflow. Routine assessment of IAP may help clinicians to identify remediable causes of increased ICP. Caution should be used when applying laparoscopic techniques in neurotrauma patients.

Abdomen↗
PubMed2000

Postcontraction depression of reciprocal inhibition in human forearm muscles.

We tested whether a preceding muscle contraction changes reciprocal inhibition (RI) between forearm antagonists. RI was studied in 14 healthy subjects by assessing changes in the H reflex (evoked by median-nerve stimulation) in forearm flexor muscles after conditioning radial-nerve stimulation at 0- and 20-ms intervals. The maximum sizes of the M wave (M(max)) and H reflex (H(max)) were also measured. After a long-lasting maximum voluntary handgrip contraction (mean +/- SEM: 3.9 +/- 0.6 min) of ipsilateral forearm muscles, M(max) and H(max) were unchanged but RI was diminished. After contraction of the contralateral homologous muscles and after contraction elicited by ipsilateral muscle stimulation, RI remained unchanged. These results show that a preceding maximum voluntary contraction (lasting 30 s or more) reduces the activity of the spinal inhibitory interneurons mediating RI. This finding may imply the need to reinterpret results from RI studies in normal subjects and in patients with movement disorders.

Adult↗
PubMed2000

Effects of periodic lung recruitment maneuvers on gas exchange and respiratory mechanics in mechanically ventilated acute respiratory distress syndrome (ARDS) patients.

OBJECTIVE: We wished to investigate whether volume recruitment maneuvers (VRMs) could improve alveolar recruitment and oxygenation in acute respiratory distress syndrome (ARDS) patients, ventilated at relatively low positive end-expiratory pressure (PEEP). SETTING: General intensive care unit (ICU) located in a teaching hospital. PATIENTS: 15 PEEP responder ARDS patients undergoing continuous positive pressure ventilation (CPPV) with sedation and muscle paralysis. INTERVENTIONS: We identified a low (9.4 +/- 3 cmH2O) and a high (16.0 +/- 2 cmH2O) level of PEEP associated with target oxygenation values. Using a custom modified mechanical ventilator, we applied in random order three steps lasting 30 min: (1) CPPV at the low PEEP level (CPPV(LO)); (2) CPPV at the high PEEP level (CPPV(HI)); (3) CPPV at low PEEP with the superimposition of periodic VRMs (CPPV(VRM)). VRMs were performed twice a minute by increasing PEEP to the high level for two breaths. Each brace of two breaths was spaced 30 seconds from the preceding one. MEASUREMENTS AND RESULTS: We measured gas exchange, hemodynamics, respiratory mechanics, and the end expiratory lung volume (EELV). Compared to CPPV(LO), CPPV(VRM) resulted in higher PaO2 (117.9 +/- 40.6 vs 79.4 +/- 13.6 mmHg, P < 0.01) and EELV (1.50 +/- 0.62 vs 1.26 +/- 0.50 l, P < 0.05), and in lower venous admixture (Q(VA)/Q(T)) (0.42 +/- 0.07 vs 0.48 +/- 0.07, P < 0.01). During CPPV(HI), we observed significantly higher PaO2 (139.3 +/- 32.5 mmHg) and lower Q(VA)/Q(T) (0.37 +/- 0.08) compared to CPPV(LO) (P < 0.01) and to CPPV(VRM) (P < 0.05). CONCLUSIONS: VRMs can improve oxygenation and alveolar recruitment during CPPV at relatively low PEEP, but are relatively less effective than a continuous high PEEP level.

Adult↗
PubMed2000

Control of fever by continuous, low-dose diclofenac sodium infusion in acute cerebral damage patients.

OBJECTIVES: The aim of this study was to assess the efficacy and safety of low doses of diclofenac sodium (DCF) in attaining normothermia with minimal major side effects in patients with acute cerebral damage. The study was designed to verify the adequate, prolonged antipyretic action of DCF infusion, to quantify its haemodynamic and cerebral impact and to assess any negative effect on renal and liver function. DESIGN: Retrospective, cohort study on prospectively collected data. SETTING: Intensive care unit (ICU) of a university hospital. PATIENT POPULATION: Five patients with subarachnoid haemorrhage and seven severe head-trauma victims with febrile illness of various infectious origin. INTERVENTIONS: Continuous i.v. infusion of a low dose (0.04 mg/kg/h) of DCF for 48 h. MEASUREMENTS AND RESULTS: Systemic and cerebral haemodynamic data were collected at 4 h intervals for 8 h before diclofenac infusion and 48 h after. Renal and liver functions were monitored. Normothermia, defined as external temperature < 37.5 degrees Celsius (degrees C), was achieved in all cases. Intracranial pressure was significantly lowered and mean arterial pressure was unaffected, so cerebral perfusion pressure rose after DCF. Hepatic and renal function were not altered in the 48 h post DCF. Mean urinary output was preserved at high flow and was not influenced by DCF. CONCLUSIONS: Continuous infusion of low-dose DCF attained normothermia without any major cerebral or systemic side effects. Renal and liver functions were unaffected. Once normothermia was achieved, intracranial and cerebral perfusion pressure improved.

Acute Disease↗
PubMed2000

Pressure support ventilation in patients with acute lung injury.

OBJECTIVES: To assess the success rate of pressure support ventilation (PSV) in acute lung injury patients undergoing continuous positive pressure ventilation (CPPV), to study physiologic changes after the transition from CPPV to PSV, and to investigate differences between patients who succeed and patients who fail PSV according to predetermined criteria. DESIGN: Observational study. SETTING: General intensive care unit in a teaching hospital. SUBJECTS: We studied 48 patients having acute lung injury, as defined by a PaO2/F(IO2) <300 mm Hg and the presence of bilateral infiltrates on chest radiograph, and ventilated with CPPV. We included patients with PaO2 >80 mm Hg, at positive end-expiratory pressure of <15 cm H2O and with F(IO2) up to 1.0. INTERVENTIONS: After enrollment, PSV was instituted and patients were strictly monitored during the following 48 hrs. Subjects who met any of the predefined PSV failure criteria during this period were returned to CPPV (Group F). PSV was continued in the remaining patients (Group S). MEASUREMENTS AND MAIN RESULTS: Gas exchange, respiratory mechanics, and hemodynamics measurements were collected before switching from CPPV to PSV and were repeated at 24 hrs after beginning PSV, or immediately before return to CPPV in Group F patients. The physiologic deadspace volume to tidal volume ratio (V(D)/V(T)) was obtained by the Enghoff's equation from the measurement of the mixed expired CO2 fraction. PSV resulted in a significant PaCO2 decrease (49.2+/-10.9 mm Hg to 44.4+/-7.2 mm Hg) and significant increases in minute volume (V(E))(9.0+/-2.3 L/min to 12.0+/-4.0 L/min) and arterial blood pH (7.405+/-0.054 to 7.435+/-0.064), with stable oxygenation and hemodynamics. In patients who were hypercapnic (PaCO2 >50 mm Hg) during CPPV, the V(E) increase was higher than in normocapnic patients. In the latter patients, PaCO2 and pH did not change significantly going from CPPV to PSV. A total of 38 patients (79%) were allocated to Group S and the remaining 10 patients were included in Group F. In Group S, positive endexpiratory pressure of 9.4+/-2.9 cm H2O (range, 3-14 cm H2O) and a PSV level of 14.9+/-3.8 cm H2O (range, 9-22 cm H2O) were applied. In Group F, positive end-expiratory pressure of 8.9+/-3.1 cm H2O (range, 5-15 cm H2O) and a PSV level of 21.6+/-4.6 cm H2O (range, 16-31 cm H2O) were adopted. Compared with Group S, Group F had a longer duration of intubation (20.2+/-19.2 days vs. 9.2+/-13.5 days), a lower static compliance of the respiratory system (30.4+/-16.5 mL/cm H2O vs. 41.7+/-15.0 mL/cm H2O), and a higher V(D)/V(T) (0.70+/-0.09 vs. 0.52+/-0.10), but similar oxygenation and positive end-expiratory pressure. V(E) was higher in Group F during both CPPV and PSV. CONCLUSIONS: In a relatively high proportion of the investigated patients, PSV was successful. The institution of PSV led to no major changes in oxygenation or in hemodynamics. PSV was associated with increases in V(E) and respiratory frequency. In patients who had been hypercapnic during CPPV, PaCO2 decreased despite a compensated pH. Compared with PSV success patients, patients who failed PSV appeared to be sicker, as shown by the higher duration of respiratory support, increased ventilatory needs, and decreased respiratory system compliance, despite similar arterial oxygenation and positive end-expiratory pressure.

Acid-Base Equilibrium↗
PubMed2000

Hemodynamic and gas exchange response to inhaled nitric oxide and prone positioning in acute respiratory distress syndrome patients.

OBJECTIVE: To analyze the single effect and the interaction of prone position and inhaled nitric oxide (iNO) on lung function and hemodynamic variables. DESIGN: 2 x 2 factorial trial. SETTING: Department of intensive care medicine at a university hospital. PATIENTS: Fourteen patients on volume-controlled mechanical ventilation for acute respiratory distress syndrome (ARDS). INTERVENTION: Four experimental conditions, each one characterized by the patient's position (supine or prone) with iNO or without iNO. MEASUREMENTS AND RESULTS: Hemodynamic and gas exchange data were collected for each experimental condition. PaO2 was increased both by positioning (p < .01) and iNO (p < .01); iNO caused also a reduction in venous admixture (p < .01), pulmonary artery pressure (p < .01), and pulmonary vascular resistance index (p < .05). We could not demonstrate any significant interaction between the two treatments. The average effect of prone positioning was the same both with and without iNO, whereas the average effect of iNO was the same in both the prone and the supine position. CONCLUSION: In the studied acute respiratory distress syndrome patients the average effects of iNO and positioning on oxygenation were additive and no interaction could be shown. A strategy including both treatments could warrant the best improvement in oxygenation, and should take into account the individual response to each treatment and the possible combination of the two.

Administration, Inhalation↗
PubMed2000

Reverse-thrust ventilation in hypercapnic patients with acute respiratory distress syndrome. Acute physiological effects.

Techniques of tracheal gas insufflation (TGI) have been shown to enhance CO(2) clearance efficiency in mechanically ventilated patients with acute respiratory distress syndrome (ARDS). Clinical studies have explored the effects of such techniques only at moderate intratracheal gas flow rates, with TGI superimposed to mechanical ventilation in a continuous fashion, or synchronized to the expiratory phase of the duty cycle. We examined the effects of intratracheal pulmonary ventilation (ITPV), delivering the entire tidal volume (VT) in the proximity of the tracheal carina, with all the gas flow supplied continuously through a reverse-thrust catheter (RTC). A potential limitation in the application of TGI is dynamic hyperinflation. Therefore, in a subgroup of patients, we also evaluated the effects of ITPV on end-expiratory lung volume (EELV) by respiratory inductive plethysmography (RIP). Eleven patients with ARDS under volume-cycled mechanical ventilation were subsequently switched to ITPV at the same baseline respiratory rate, I:E ratio, and VT. At the same minute volume, Pa(CO(2)) decreased from 70 +/- 12.3 to 59 +/- 9.5 mm Hg, with a percent reduction of 15 +/- 4% (range from 10 to 20%). The CO(2) decrease was greater in patients with higher baseline Pa(CO(2)) levels (DeltaPa(CO(2)) = 0.29 x Pa(CO(2)) - 9.48, r = 0.95). During transition from mechanical ventilation to ITPV, tracheal positive end-expiratory pressure (PEEP(tr)) decreased with a correspondent decrease in EELV. Both were restored by increasing the PEEP at the ventilator by 3.6 +/- 2.0 cm H(2)O. These data suggest that in patients with ARDS ITPV effectively reduces dead space ventilation and the employment of the RTC may limit or avoid dynamic hyperinflation.

Adult↗