Impairment of respiratory muscle strength in Berardinelli-Seip congenital lipodystrophy subjects.

BACKGROUND: Berardinelli-Seip Congenital Generalized Lipodystrophy (BSCL) is an ultra-rare metabolic disease characterized by hypertriglyceridemia, hyperinsulinemia, hyperglycemia, hypoleptinemia, and diabetes mellitus. Although cardiovascular disturbances have been observed in BSCL patients, there are no studies regarding the Respiratory Muscle Strength (RMS) in this type of lipodystrophy. This study aimed to evaluate RMS in BSCL subjects compared with healthy subjects. METHODS: Eleven individuals with BSCL and 11 healthy subjects matched for age and gender were included in this study. The Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP), and Peripheral Muscle Strength (PMS) were measured for three consecutive years. BSCL subjects were compared to healthy individuals for MIP, MEP, and PMS. Correlations between PMS and MIP were also analyzed. The genetic diagnosis was performed, and sociodemographic and anthropometric data were also collected. RESULTS: BSCL subjects showed significantly lower values for MIP and MEP (p <  0.0001 and p = 0.0002, respectively) in comparison to healthy subjects, but no changes in handgrip strength (p = 0.15). Additionally, we did not observe changes in MIP, MEP, and PMS two years after the first analysis, showing maintenance of respiratory dysfunction in BSCL subjects (p = 0.05; p = 0.45; p = 0.99). PMS and MIP were not correlated in these subjects (r = 0.56; p = 0.18). CONCLUSION: BSCL subjects showed lower respiratory muscle strength when compared with healthy subjects; however, PMS was not altered. These findings were maintained at similar levels during the two years of evaluation. Our data reveal the first association of BSCL with the development of respiratory muscle weakness.

Effect of pyridostigmine on in vivo and in vitro respiratory muscle of mdx mice.

The current work was conducted to verify the contribution of neuromuscular transmission defects at the neuromuscular junction to Duchenne Muscular Dystrophy disease progression and respiratory dysfunction. We tested pyridostigmine and pyridostigmine encapsulated in liposomes (liposomal PYR), an acetylcholinesterase inhibitor to improve muscular contraction on respiratory muscle function in mdx mice at different ages. We evaluated in vivo with the whole-body plethysmography, the ventilatory response to hypercapnia, and measured in vitro diaphragm strength in each group. Compared to C57BL10 mice, only 17 and 22 month-old mdx presented blunted ventilatory response, under normocapnia and hypercapnia. Free pyridostigmine (1mg/kg) was toxic to mdx mice, unlike liposomal PYR, which did not show any side effect, confirming that the encapsulation in liposomes is effective in reducing the toxic effects of this drug. Treatment with liposomal PYR, either acute or chronic, did not show any beneficial effect on respiratory function of this DMD experimental model. The encapsulation in liposomes is effective to abolish toxic effects of drugs.

Fish Oil Supplementation Enhances Pulmonary Strength and Endurance in Women Undergoing Chemotherapy.

We investigated the effect of fish oil (FO) supplementation, at 4 g/day, on the respiratory performance and blood lipid profile of 32 patients with breast cancer at the beginning of chemotherapy. They were randomized into two groups: control (C) and FO supplemented (S). Both groups underwent three respiratory evaluations and blood harvest (before chemotherapy-Day 0, and 30 and 60 days after supplementation). The S group showed a significant increase in the maximal inspiratory and expiratory pressure (P ≤ 0.05 vs. Day 0) and in the maximum voluntary ventilation (P ≤ 0.05). In the treadmill 6-min-walk test, the S group had a significant increase in the walked distance (P ≤ 0.05). Blood lactate concentration was significantly lower in the S group after 60 days, at rest, when compared to C (P ≤ 0.05). Plasma high-density lipoprotein (HDL) cholesterol concentration remained the same after 60 days of supplementation, while in the C group, it decreased significantly (P ≤ 0.05 Day 0 vs. Day 60). Triacylglycerol (TAG) plasma concentration in the S group was lower when compared to the C group (P ≤ 0.05 Day 60S vs. Day 60). Supplementation with FO caused improvement in the respiratory muscle strength and endurance, ameliorated functional performance, and kept TAG, HDL cholesterol, and lactate plasma concentration at normal levels.

Addition of tiotropium to formoterol improves inspiratory muscle strength after exercise in COPD.

BACKGROUND: The addition of tiotropium bromide (TIO) to formoterol fumarate (FOR) improves exercise performance in patients with chronic obstructive pulmonary disease (COPD). In this study, we test the hypothesis that the addition of TIO to FOR may improve respiratory muscle performance and oxygen uptake kinetics after exercise in patients with COPD. METHODS: Thirty eight patients with COPD were randomized to a 2 week treatment with FOR 12 µg twice a day plus TIO 18 µg once a day (FOR + TIO) or FOR 12 µg twice a day plus placebo (FOR + PLA) once a day, using a double-blind crossover design. Inspiratory muscle. Strength was measured before, immediately after, as well as 2, 5, and 10 min during recovery of exercise. Time to limit of tolerance on a constant work load exercise test and oxygen uptake kinetics during recovery were evaluated before and after intervention. RESULTS: Only FOR + TIO improved resting (63 ± 10 cm to 84 ± 11 cmH(2)O) and post-exercise (49 ± 7 cm to 84 ± 11 cmH(2)O) maximal inspiratory pressure. Time to limit of tolerance on the constant work load test was increased by FOR + PLA and by FOR + TIO, but the size of the increment was significantly larger with FOR + TIO (40.7 ± 7.6% vs. 84.5 ± 8.2%; p < 0.05). Only FOR + TIO improved oxygen uptake kinetics during recovery (69 ± 21 to 60 ± 18 s). The improvement in maximal inspiratory pressure (0.78, p < 0.001) and in oxygen uptake kinetics (-0.91, p < 0.001) correlated with the change in time to the limit of tolerance. CONCLUSIONS: The addition of TIO to FOR improves inspiratory muscle strength and oxygen uptake kinetics after exercise in COPD patients.

Effects of subclinical hypothyroidism treatment on psychiatric symptoms, muscular complaints, and quality of life.

OBJECTIVES: To evaluate the impact of subclinical hypothyroidism (sHT) treatment on health-related quality of life (QoL), psychiatric symptoms, clinical score, and muscle function. MATERIALS AND METHODS: In this randomized double-blind study, patients were assigned either to treatment (n = 35) or placebo (n = 36). Clinical and psychiatric symptoms were assessed by the Zulewski, Hamilton and Beck scales. QoL was assessed by the SF-36 questionnaire. Assessments of quadriceps (QS) and inspiratory muscle (IS) strength were performed by a chair dynamometer and a manuvacuometer. RESULTS: Treatment improved IS (+11.5 ± 17.2; p = 0.041), as did QoL domains "Pain" and "Role Physical" (+19.7 ± 15.2, 0.039 and +22.1 ± 47.5, p = 0.054; respectively). Clinical and psychiatric symptoms showed similar responses to both interventions. CONCLUSIONS: sHT treatment improved IS and physical aspects of QoL, despite no impact in other muscle parameters. Clinical score, psychiatric symptoms, and SF-36 domains, based on mental dimensions of QoL may be more susceptible to "placebo effect" in patients with sHT.

Effects of subclinical hypothyroidism treatment on psychiatric symptoms, muscular complaints, and quality of life / Efeitos do tratamento do hipotiroidismo subclínico sobre sintomas psiquiátricos, queixas musculares e qualidade de vida

OBJECTIVES: To evaluate the impact of subclinical hypothyroidism (sHT) treatment on health-related quality of life (QoL), psychiatric symptoms, clinical score, and muscle function. MATERIALS AND METHODS: In this randomized double-blind study, patients were assigned either to treatment (n = 35) or placebo (n = 36). Clinical and psychiatric symptoms were assessed by the Zulewski, Hamilton and Beck scales. QoL was assessed by the SF-36 questionnaire. Assessments of quadriceps (QS) and inspiratory muscle (IS) strength were performed by a chair dynamometer and a manuvacuometer. RESULTS: Treatment improved IS (+11.5 ± 17.2; p = 0.041), as did QoL domains "Pain" and "Role Physical" (+19.7 ± 15.2, 0.039 and +22.1 ± 47.5, p = 0.054; respectively). Clinical and psychiatric symptoms showed similar responses to both interventions. CONCLUSIONS: sHT treatment improved IS and physical aspects of QoL, despite no impact in other muscle parameters. Clinical score, psychiatric symptoms, and SF-36 domains, based on mental dimensions of QoL may be more susceptible to "placebo effect" in patients with sHT.

OBJETIVOS: Avaliar o impacto do tratamento do hipotireoidismo subclínico (sHT) na qualidade de vida relacionada à saúde (QoL), aos sintomas psiquiátricos, ao escore clínico e à função muscular. MATERIAIS E MÉTODOS: Em um ensaio randomizado duplo-cego, pacientes foram randomizados para tratamento (n = 35) ou uso de placebo (n = 36). Sintomas clínicos e psiquiátricos foram acessados por meio das escalas de Zulewski, Hamilton e Beck. A QoL foi avaliada pelo questionário SF-36. Medidas da força de quadríceps (QS) e inspiratória (IS) foram obtidas por um dinamômetro de cadeira e um manovacuômetro. RESULTADOS: O tratamento melhorou a IS (+11,5 ± 17,2; p = 0,041), assim como os domínios "Dor" e "Aspectos Físicos" da QoL (+19,7 ± 15,2, 0,039 e +22,1 ± 47,5, p = 0,054, respectivamente). Sintomas clínicos e psiquiátricos demonstraram respostas similares a ambas as formas de intervenção. CONCLUSÕES: Tratamento do sHT melhorou IS e aspectos físicos da QoL, apesar de não ter impacto em outros parâmetros musculares. Escore clínico, sintomas psiquiátricos e domínios do SF-36 que focam em dimensões mentais podem ser mais suscetíveis ao "efeito placebo" em pacientes com sHT.

Electromyographic activity of sternocleidomastoid muscle in patients with Parkinson's disease.

The aim of this study was to evaluate the effect of administration of levo-dopa, which means without effect-off state and under effect-on state, on the sternocleidomastoid muscle electromyographic activity (SCM-EA) in patients with Parkinson's disease (PD) at rest and to compare it to asymptomatic subjects. Ten patients with PD, mean age 64.6+/-6.2 (SD) years and nine asymptomatic subjects, mean age 61.4+/-5.9 (SD) years were studied. The SCM-EA was evaluated during maximal inspiratory pressure and breathing at rest through surface electromyography. Statistical analysis was performed with t-test (anthropometric data and SCM-EA of patients in off state to asymptomatic), Mann-Whitney (SCM-EA of patients in on state to asymptomatic) and Wilcoxon test (SCM-EA off and on states). The effect size index (d) was calculated for statistically significant differences. There were no significant differences in SCM electromyographic activity between patients with PD comparing off to on (p=0.13) or among on state to asymptomatic subjects (p=0.06). However, when subjects with PD in off where compared to asymptomatic there was a significantly higher SCM electromyographic activity (p=0.03, d=1.09). These patients, without levo-dopa effect, when compared with asymptomatic subjects, present a significantly higher electromyographic activity of SCM, the main accessory respiratory muscle, which could be related to an increased work of breathing.

Effects of acute magnesium loading on pulmonary function of stable COPD patients.

BACKGROUND: Magnesium (Mg) use has the potential to promote bronchodilatation and to improve lung function in obstructive diseases. IV administration of Mg during exacerbations of chronic obstructive pulmonary disease (COPD) has led to improved peak flow. This study aimed to investigate the effects of acute IV Mg loading on respiratory parameters of stable COPD patients. MATERIAL/METHODS: This was a randomized, double-blind, placebo-controlled crossover study. Twenty-two male COPD patients (64+/-6 years old, FEV1: 49+/-20%) received an IV infusion of 2 g of magnesium sulfate or placebo on two distinct occasions. Spirometry and mouth maximal respiratory pressures were obtained before and 45 minutes after the infusions. RESULTS: Mg use led to significant changes in functional respiratory capacity (-0.48 l, 95%CI: -0.96, -0.01), inspiratory capacity (0.21 l, 95%CI: 0.04, 0.37), maximal inspiratory pressure (10 cmH2O, 95%CI: 1.6, 18.4), and maximal expiratory capacity (10.7 cmH2O, 95%CI: 0.20, 21.2). The treatment was also associated with a marginally significant decrease in residual volume (-0.47 L, 95%CI: -0.96, 0.02, p=0.06). CONCLUSIONS: Acute IV Mg loading in stable COPD patients was associated with a reduction in lung hyperinflation and improvement of respiratory muscle strength. The clinical potential for chronic magnesium supplementation in COPD deserves further investigation.

Effects of different nutritional support on lung mechanics and remodelling in undernourished rats.

This study investigated the impact of three different oral nutritional support regimens on lung mechanics and remodelling in young undernourished Wistar rats. In the nutritionally deprived group, rats received one-third of their usual daily food consumption for 4 weeks. Undernourished rats were divided into three groups receiving a balanced, glutamine-supplemented, or long-chain triglyceride-supplemented diet for 4 weeks. In the two control groups, rats received food ad libitum for 4 (C4) or 8 weeks. Lung viscoelastic pressure and static elastance were higher in undernourished compared to C4 rats. After refeeding, lung mechanical data remained altered except for the glutamine-supplemented group. Undernutrition led to a reduced amount of elastic and collagen fibres in the alveolar septa. Elastic fibre content returned to control with balanced and glutamine-supplemented diets, but increased with long-chain triglyceride-supplemented diet. The amount of collagen fibre augmented independent of nutritional support. In conclusion, glutamine-supplemented diet is better at reducing morphofunctional changes than other diets after 4 weeks of refeeding.

Acute action of aminophylline in patients with amyotrophic lateral sclerosis.

OBJECTIVE: This study investigated whether aminophylline has an acute effect on the muscle performance of patients with amyotrophic lateral sclerosis (ALS). The study was a randomized, double-blind, crossover against placebo. MATERIALS AND METHODS: Twenty-five patients (48.5 +/- 14.1 years) with ALS were evaluated by means of forced vital capacity (FVC), maximal mouth inspiratory and expiratory pressures (P(Imax)/P(Emax)) and endurance, maximum voluntary ventilation (MVV) and handgrip strength (HS); variables were measured before and after the patients received an intravenous infusion of aminophylline or placebo. RESULTS: MVV (P<0.02) and HS of the right and left hands (P=0.05) increased after aminophylline infusion. There was a positive correlation between FVC and P(Imax) (r=0.80; P<0.05); between MVV and P(Imax) post-aminophylline, respectively (r=0.77; P<0.05). Serum aminophylline levels ranged from 5.3 to 10.5 microg/mL (mean 7.30). CONCLUSION: The acute administration of aminophylline improves the endurance of respiratory muscles and increases handgrip strength in patients with ALS.

Strength and endurance of the respiratory and handgrip muscles after the use of flunisolide in normal subjects.

OBJECTIVE: To evaluate the effects of the inhaled flunisolide upon the strength and endurance of the respiratory and peripheral muscles of normal subjects. DESIGN: A randomized, double blind and placebo-controlled study. SETTING: A university-affiliated teaching hospital. PARTICIPANTS: Thirteen normal volunteers selected from a graduation course. INTERVENTION: Subjects were randomly allocated to receive a placebo or corticosteroid (flunisolide) to be inhaled twice a day for 4 weeks. After 2 weeks of a washout period, subjects who were receiving the placebo, received flunisolide and vise versa for another 4-week period. MEASUREMENTS AND RESULTS: Spirometry was used to define the volunteers as being normal in terms of pulmonary function. During the study, subjects performed tests of respiratory muscle function (strength and endurance), measurements of handgrip strength and endurance and anthropometric measurements. Muscle strength was measured each week while muscle endurance was measured every 2 weeks. There was no significant difference in the maximal inspiratory and expiratory pressure and handgrip strength during weeks 1-4 when the subjects used either flunisolide or placebo. However, we observed an increase in the endurance time of the respiratory and handgrip muscles in the 4th week of both flunisolide and placebo use, what may be considered due to a learning effect. CONCLUSION: Inhalation of flunisolide by normal subjects for 1 month does not cause any acute or clinically perceived effect in the peripheral or respiratory muscles.

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs.

The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 +/- 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 +/- 16 and 36 +/- 12%, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40%) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 +/- 14 vs 14 +/- 5 cmH2O, and 87 +/- 30 vs 34 +/- 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 +/- 0.7 vs 2.3 +/- 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

L-carnitine as an ergogenic aid for patients with chronic obstructive pulmonary disease submitted to whole-body and respiratory muscle training programs

The effects of adding L-carnitine to a whole-body and respiratory training program were determined in moderate-to-severe chronic obstructive pulmonary disease (COPD) patients. Sixteen COPD patients (66 ± 7 years) were randomly assigned to L-carnitine (CG) or placebo group (PG) that received either L-carnitine or saline solution (2 g/day, orally) for 6 weeks (forced expiratory volume on first second was 38 ± 16 and 36 ± 12 percent, respectively). Both groups participated in three weekly 30-min treadmill and threshold inspiratory muscle training sessions, with 3 sets of 10 loaded inspirations (40 percent) at maximal inspiratory pressure. Nutritional status, exercise tolerance on a treadmill and six-minute walking test, blood lactate, heart rate, blood pressure, and respiratory muscle strength were determined as baseline and on day 42. Maximal capacity in the incremental exercise test was significantly improved in both groups (P < 0.05). Blood lactate, blood pressure, oxygen saturation, and heart rate at identical exercise levels were lower in CG after training (P < 0.05). Inspiratory muscle strength and walking test tolerance were significantly improved in both groups, but the gains of CG were significantly higher than those of PG (40 ± 14 vs 14 ± 5 cmH2O, and 87 ± 30 vs 34 ± 29 m, respectively; P < 0.05). Blood lactate concentration was significantly lower in CG than in PG (1.6 ± 0.7 vs 2.3 ± 0.7 mM, P < 0.05). The present data suggest that carnitine can improve exercise tolerance and inspiratory muscle strength in COPD patients, as well as reduce lactate production.

The influence of 6 months of oral anabolic steroids on body mass and respiratory muscles in undernourished COPD patients.

STUDY OBJECTIVE: To evaluate the influence of oral anabolic steroids on body mass index (BMI), lean body mass, anthropometric measures, respiratory muscle strength, and functional exercise capacity among subjects with COPD. DESIGN: Prospective, randomized, controlled, double-blind study. SETTING: Pulmonary rehabilitation program. PARTICIPANTS: Twenty-three undernourished male COPD patients in whom BMI was below 20 kg/m2 and the maximal inspiratory pressure (PImax) was below 60% of the predicted value. INTERVENTION: The study group received 250 mg of testosterone i.m. at baseline and 12 mg of oral stanozolol a day for 27 weeks, during which time the control group received placebo. Both groups participated in inspiratory muscle exercises during weeks 9 to 27 and cycle ergometer exercises during weeks 18 to 27. MEASUREMENTS AND RESULTS: Seventeen of 23 subjects completed the study. Weight increased in nine of 10 subjects who received anabolic steroids (mean, +1.8+/-0.5 kg; p<0.05), whereas the control group lost weight (-0.4+/-0.2 kg). The study group's increase in BMI differed significantly from that of the control group from weeks 3 to 27 (p<0.05). Lean body mass increased in the study group at weeks 9 and 18 (p<0.05). Arm muscle circumference and thigh circumference also differed between groups (p<0.05). Changes in PImax (study group, 41%; control group, 20%) were not statistically significant. No changes in the 6-min walk distance or in maximal exercise capacity were identified in either group. CONCLUSION: The administration of oral anabolic steroids for 27 weeks to malnourished male subjects with COPD was free of clinical or biochemical side effects. It was associated with increases in BMI, lean body mass, and anthropometric measures of arm and thigh circumference, with no significant changes in endurance exercise capacity.

Efecto agudo del lorazepam sobre los musculos respiratorios en los pacientes con EPOC estable / Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease

Con el objetivo de aclarar los efectos de las benzodiacepinas sobre los músculos respiratorios en pacientes con sobrecarga crónica de los mismos debida a enfermedad pulmonar obstructiva crónica (EPOC), se estudiaron 9 pacientes estables con EPOC avanzado (volumen espiratorio forzado en 1 segundo - FEV 1- 0,91 + 0,31 litros), en quienes, antes y 1 hora después de la administración de lorazepam 1,5 a 2 mg por vía sublingual, se evaluaron la capacidad vital forzada (FVC), FEV 1, ventilación voluntaria máxima (MVV), presión arterial de oxígeno (PaO2), presión arterial de anhídrido carbónico (PaCO2), volumen corriente (Vt), frecuencia respiratória (f), ventilación por minuto (Ve), tiempo inspiratorio/tiempo total (Ti/Ttot), flujo inspiratorio medio (Vi), presiones bucales máximas: máxima presión inspiratoria (MIP) y máxima presión espiratoria (MEP), presión pleural máxima (Pplmax), presiones transdiafragmáticas durante diferentes maniobras (Pdi) y mediciones de la fuerza y resistencia de los músculos esqueléticos. Tras la administración del lorazepam no se encontraron cambios en la espirometría (FVC, FEV1, ni FEV1/FVC), aunque sí existió una reducción del 20 por ciento en la Ve, debida a una minución en el Vt, que se acompañó de un pequeño pero significativo incremento en la PaCO2. La fuerza y resistencia de los músculos esqueléticos disminuyó significativamente (22 y 50 por ciento respectivamente), al igual que la MIP, MEP, MVV, Ppl y Pdi, que mostraron también reducciones significativas. Se concluye que una dosis única de lorazepam por vía sublingual, a la par que disminuye la ventilación, reduce la fuerza y la resistencia de la musculatura respiratoria en pacientes con EPOC en situación estable.

Efecto agudo del lorazepam sobre los musculos respiratorios en los pacientes con EPOC estable / Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease

Con el objetivo de aclarar los efectos de las benzodiacepinas sobre los músculos respiratorios en pacientes con sobrecarga crónica de los mismos debida a enfermedad pulmonar obstructiva crónica (EPOC), se estudiaron 9 pacientes estables con EPOC avanzado (volumen espiratorio forzado en 1 segundo - FEV 1- 0,91 + 0,31 litros), en quienes, antes y 1 hora después de la administración de lorazepam 1,5 a 2 mg por vía sublingual, se evaluaron la capacidad vital forzada (FVC), FEV 1, ventilación voluntaria máxima (MVV), presión arterial de oxígeno (PaO2), presión arterial de anhídrido carbónico (PaCO2), volumen corriente (Vt), frecuencia respiratória (f), ventilación por minuto (Ve), tiempo inspiratorio/tiempo total (Ti/Ttot), flujo inspiratorio medio (Vi), presiones bucales máximas: máxima presión inspiratoria (MIP) y máxima presión espiratoria (MEP), presión pleural máxima (Pplmax), presiones transdiafragmáticas durante diferentes maniobras (Pdi) y mediciones de la fuerza y resistencia de los músculos esqueléticos. Tras la administración del lorazepam no se encontraron cambios en la espirometría (FVC, FEV1, ni FEV1/FVC), aunque sí existió una reducción del 20 por ciento en la Ve, debida a una minución en el Vt, que se acompañó de un pequeño pero significativo incremento en la PaCO2. La fuerza y resistencia de los músculos esqueléticos disminuyó significativamente (22 y 50 por ciento respectivamente), al igual que la MIP, MEP, MVV, Ppl y Pdi, que mostraron también reducciones significativas. Se concluye que una dosis única de lorazepam por vía sublingual, a la par que disminuye la ventilación, reduce la fuerza y la resistencia de la musculatura respiratoria en pacientes con EPOC en situación estable. (AU)

[Acute effect of lorazepam on respiratory muscles in stable patients with chronic obstructive pulmonary disease]. / Efecto agudo del lorazepam sobre los musculos respiratorios en los pacientes con EPOC estable.

Benzodiazepines are known to cause muscle hypotonia, but their effects on respiratory muscle function, particularly on diaphragm, have not yet been studied. Our aim was to look for any effect of lorazepam on respiratory muscle function in patients with chronic obstructive pulmonary disease (COPD). Nine stable COPD patients (mean +/- SD forced expiratory volume in one second (FEV1) 0.91 +/- 0.31 l) were included in the study. The following measurements were performed before and 1 hour after lorazepam administration (doses: 1.5 to 2 mg) by sublingual route: forced vital capacity (FVC), FEV1, maximal voluntary ventilation (MVV), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2), minute ventilation (Ve), tidal volume (Vt), respiratory rate (f), inspiratory time/inspiratory plus expiratory time (Ti/Ttot)-, mean inspiratory flow (Vi), maximal inspiratory (MIP) and expiratory (MEP) pressures, maximal pleural pressure (Pplmax), transdiaphragmatic pressures (Pdi) and skeletal muscle strength and endurance. As expected, no change was noted in FVC, FEV1, FEV1/FVC (Table-1). Besides stability of expiratory flows, this denotes no change in collaboration in spite of the sedative effects of lorazepam. There was a 20% decrease in Ve, due to a Vt reduction and a small increase in PaCO2. These could be explained by the central effects of benzodiazepines. Skeletal muscle strength and endurance decreased significantly (22 and 50% respectively-Table 2), in accordance with the previously reported muscular actions of this pharmacological group. Respiratory muscle function parameters, MIP, MEP, MVV and Ppl showed significant reductions (10 to 20 per cent), as was the case with diaphragmatic function measured by Pdi (Muller maneuver with abdominal protrussion and maximal open-glottis expulsive maneuver) (Table 3). This study demonstrates that a single lorazepam dose reduces strength and endurance of respiratory muscle in chronic stable COPD patients.