[Respiratory and physical recovery in cervical spinal cord injury. Seventeen years' experience in a weaning and rehabilitation center: An observational study]. / Evolución respiratoria y motora en lesión medular cervical. Diecisiete años de experiencia en un centro de desvinculación de asistencia ventilatoria mecánica: un estudio observacional.

INTRODUCTION AND OBJECTIVES: Spinal cord injury (SCI) is a devastating entity that generates substantial disability. The outcome of respiratory and motor features has an impact in human and social well-being. We analyzed demographic characteristics, motor and respiratory outcomes, and determined equipment needs at discharge in a weaning and rehabilitation center. MATERIAL AND METHOD: Observational, descriptive and retrospective study of medical records between January 2002 and December 2018. Tracheostomised cervical SCI patients with invasive mechanical ventilation were included. Forced vital capacity (upright and supine), maximal inspiratory and expiratory pressures, ASIA and Spinal Cord Independence MeasureIII (SCIMIII) were obtained. RESULTS: Of 1603 patients, 3.5% had SCI, and 28 met the inclusion criteria. The most frequent level of injury was C4-C5 (17/28), 21/28 had ASIAA classification, and 19 showed no change in either the ASIA or the SCIM score. In all, 22/28 patients were weaned, while 15/28 were decannulated. Twenty four patients were discharged to home. The most relevant change in SCIMIII was in the 5th component of respiration and sphincter subscale, related to weaning and tracheostomy. At discharge, 23/24 patients needed both respiratory and motor aids. CONCLUSIONS: The admission rate of SCI patients was low in our weaning and rehabilitation center, with almost all being admitted for traumatic causes. Severity remained unchanged in most ASIAA patients. Respiratory recovery was more clinically significant than recovery of motor function. Upon discharge, most of our patients had to be equipped with both respiratory and motor aids.

[Functional respiratory evaluation in patients with high traumatic spinal injury]. / Evaluación funcional respiratoria en pacientes con lesión medular traumática alta.

The restrictive defect was quantified (Forced vital capacity, FVC) and their postural dependence and the respiratory muscle weakness (Maximal inspiratory and expiratory pressures, MIP and MEP) in 29 patients (12 to 46 years) with spinal injury from cervical (C) 4 to thoracic (T) 7 (30 days to 48 months post injury period). The FVC in C (seated) was 2200 +/- 560 ml (47.2%), and in T was 2940 +/- 750 ml (66.6%), p < 0.008. The postural dependence of the FVC was higher in C with an increase of 25% and only of 10% in the T (p < 0.03). This postural dependence was a function of the FVC according to the regression equation: FVC % (supine) = 24.73+ 0.7341* FVC % seated (r 0.8771, p < 0.001). The MIP in C was 61.59 (53.82%) +/- 17.26 cm H2O and in T was 87.25 (77.85%) +/- 24.27 cmH2O (p < 0.05). The MEP in C was 48.53 (24.97%) +/- 18.09 cm H2O, and in T was 58.75 (30.74%) +/- 27.67 cmH2O (p NS). No correlation was found between FVC and maximal statics respiratory pressures. In conclusion, the C showed more significant restrictive defect and a great postural dependence of the FVC. In both, the expiratory muscle weakness was more severe than the inspiratory group. Inspiratory muscle weakness was higher in C.

Evaluación funcional respiratoria en pacientes con lesión medular traumática alta. / [Functional respiratory evaluation in patients with high traumatic spinal injury]

The restrictive defect was quantified (Forced vital capacity, FVC) and their postural dependence and the respiratory muscle weakness (Maximal inspiratory and expiratory pressures, MIP and MEP) in 29 patients (12 to 46 years) with spinal injury from cervical (C) 4 to thoracic (T) 7 (30 days to 48 months post injury period). The FVC in C (seated) was 2200 +/- 560 ml (47.2

), and in T was 2940 +/- 750 ml (66.6

), p < 0.008. The postural dependence of the FVC was higher in C with an increase of 25

and only of 10

in the T (p < 0.03). This postural dependence was a function of the FVC according to the regression equation: FVC

(supine) = 24.73+ 0.7341* FVC

seated (r 0.8771, p < 0.001). The MIP in C was 61.59 (53.82

) +/- 17.26 cm H2O and in T was 87.25 (77.85

) +/- 24.27 cmH2O (p < 0.05). The MEP in C was 48.53 (24.97

) +/- 18.09 cm H2O, and in T was 58.75 (30.74

) +/- 27.67 cmH2O (p NS). No correlation was found between FVC and maximal statics respiratory pressures. In conclusion, the C showed more significant restrictive defect and a great postural dependence of the FVC. In both, the expiratory muscle weakness was more severe than the inspiratory group. Inspiratory muscle weakness was higher in C.

Effects of spontaneous and hypercapnic hyperventilation on inspiratory effort sensation in normal subjects.

In order to elucidate if the inspiratory effort sensation (IES) associated with carbon dioxide (CO2) is independent of the concomitant increase in the ventilation, we studied 23 normal resting volunteers (mean age 34 +/- 11 yr) during CO2 rebreathing. Our main goal was to compare the IES at the same ventilation level under hypercapnic and isocapnic conditions. The protocol included: (1) basal measurements (BASAL); (2) hypercapnic ventilation (HV); (3) screen copy of ventilatory pattern during hypercapnia (COPY); (4) screen copy at basal end-tidal (partial) carbon dioxide pressure (PETCO2) (ISO); and (5) recovery (REC). During HV, PETCO2 increased to 54.8 +/- 0.78 mm Hg (p < 0.001) and ventilation (VE) from 12.0 +/- 0.50 to 28.1 +/- 1.19 L/min (p < 0.001). Borg value increased from 0.11 +/- 0.06 to 3.4 +/- 0.23 (p < 0.001). These values were not different during HV and COPY. During ISO, PETCO2 was 40.2 +/- 0. 59 mm Hg (not significant [NS] from BASAL), while VE remained unchanged: 29.9 +/- 1.29 L/min (NS from HV and COPY). Interestingly, the Borg value during the ISO decreased to 1.86 +/- 0.28 (p < 0.001 compared with HV and COPY). The increased IES induced by hypercapnic ventilation was reduced at the same ventilation level during isocapnic conditions. We suggest that CO2 generates an IES independent of the concomitant increase in ventilation.

[Clinical and spirometric alterations in patients with Duchenne muscular dystrophy]. / Comportamiento clínico y espirométrico de pacientes con distrofia muscular de Duchenne.

In 36 patients with Duchenne muscular dystrophy we studied the growth pattern, the type and severity of the spirometric abnormalities, the evolution of the Motor Functional Class (MFC), the infectious complications and treatments. Their age ranged from 6 to 19 years and the MFC was from 1 to 9. Regarding height, up to 12 years we verified a slope of 5.69 +/- 0.58 cm/year (r 0.872 p < 0.001) and a posterior detention was observed. Of the 36 patients, 24 were below the percentile 5. The restrictive disorder prevailed. The forced vital capacity (FVC) expressed in % of the theoretical value showed a lineal fall with age, with a negative correlation (r 0.51, p < 0.01) of -3.5 +/- 0.83%/year. The deterioration of the MFC was marked starting from 6 years; with a slope of 0.84 +/- 0.14 points between 6 to 12 years (r 0.73 p x 0.001). Up to 14 years, the slope was 0.212 +/- 0.084 (r 0.49, p < 0.05). Patients older than 14 years had reached a greater CFM of 7; starting from this MFC a progressive fall of the VC was observed with a slope of -15.29 +/- 3.39% of CVF/CF (r 0.56, p < 0.001). Nine patients with respiratory infections were documented. Four were pneumonia and 3 of them required mechanical ventilation and died. Only 50% of the patients accepted rehabilitating treatment. Four patients accepted surgery of the alterations of the feet while the patients with deformation of the column underwent spinal stabilization.

Bilateral diaphragmatic paralysis after mediastinal radiotherapy.

A 35-year-old man presented bilateral phrenic paralysis 7 months after radio-therapy for treatment of Hodgkin's lymphoma. Diaphragmatic dysfunction appeared after complete lymphoma remission and 4 months after chemotherapy discontinuation. There were no other potential causes. Idiopathic diaphragmatic paralysis was unlikely because it is usually unilateral. Radiation-induced neuropathy is well documented in other nerves as the brachial plexus. The timing, the applied dose and the location of the nerve within the radiation field are suggestive of radiation-induced phrenic nerve damage. Partial recovery was achieved after 4 years' follow-up.

[Effects of experimental ascites on diaphragm strength]. / Efectos de la ascitis experimental sobre la generación de fuerza del diafragma.

We studied the strength developed by the diaphragm during progressive ascitis induction (40 up to 280 ml/kg wt) and the changes in the radium of curvature in relation with its strength in 6 anesthetized dogs. Force generation of the diaphragm was assessed with the Pdi obtained with bilateral phrenic nerve stimulation at 60 Hz. In relation to increases in the abdominal liquid, the thoraco-pulmonary compliance decreases (p < 0.05) from 10.1 to 6.8 ml/kg/cm H2O. The radius of curvature increases 158% from the basal values; the calculated basal tension was 347 +/- 43, final 448 +/- 32 cm H2O/cm. The diaphragmatic length in percent of the basal value was 138%. The X-rays findings showed cephalic displacement, diaphragmatic flattening and stretching. The Pdi obtained should be the result of a complex interaction between the diaphragmatic geometry, the length, the degree of stretching during the contraction and preload. We can describe the changes in Pdi in 2 steps: initial increase and final decrease, associated to high Pga at the beginning and a low one later. First the Pdi increases by the Pga without significant changes in the Pes. The fact is that an increase in Pga can be related with cephalic displacement of the diaphragm with stretching and shortening of the radius of curvature and decreases in the abdominal compliance. The final decreases in the Pdi could be related with overstretching and decreases of the radius of curvature.

Efectos de la ascitis experimental sobre la generación de fuerza del diafragma. / [Effects of experimental ascites on diaphragm strength]

We studied the strength developed by the diaphragm during progressive ascitis induction (40 up to 280 ml/kg wt) and the changes in the radium of curvature in relation with its strength in 6 anesthetized dogs. Force generation of the diaphragm was assessed with the Pdi obtained with bilateral phrenic nerve stimulation at 60 Hz. In relation to increases in the abdominal liquid, the thoraco-pulmonary compliance decreases (p < 0.05) from 10.1 to 6.8 ml/kg/cm H2O. The radius of curvature increases 158

from the basal values; the calculated basal tension was 347 +/- 43, final 448 +/- 32 cm H2O/cm. The diaphragmatic length in percent of the basal value was 138

. The X-rays findings showed cephalic displacement, diaphragmatic flattening and stretching. The Pdi obtained should be the result of a complex interaction between the diaphragmatic geometry, the length, the degree of stretching during the contraction and preload. We can describe the changes in Pdi in 2 steps: initial increase and final decrease, associated to high Pga at the beginning and a low one later. First the Pdi increases by the Pga without significant changes in the Pes. The fact is that an increase in Pga can be related with cephalic displacement of the diaphragm with stretching and shortening of the radius of curvature and decreases in the abdominal compliance. The final decreases in the Pdi could be related with overstretching and decreases of the radius of curvature.

[Central alveolar hypoventilation with cor pulmonale: successful treatment by non-invasive intermittent positive pressure ventilation]. / Hipoventilación alveolar central con cor pulmonale: tratamiento exitoso mediante ventilación con presión positiva intermitente no invasiva.

A 62 year-old woman with a bilateral carotid body paraganglioma presented, 2 years after the removal of the right one, with signs of right-heart failure. Hypoxemia, hypercapnia, polycythemia and pulmonary hypertension with normal ventilatory capacity were found. Central alveolar hypoventilation was diagnosed on the basis of absence of ventilatory response and sensation of provoked hypercapnia, prolonged breath-holding time and correction of hypercapnia by voluntary ventilation. Progesterone (200 mg/d during 3 weeks) or naloxone did not improve either arterial blood gases (ABG) or the P 0.1/PCO2 curve. Hypoxemia and hypercapnia were not corrected during metabolic acidosis provoked by acetazolamide (250 mg/d). Nasal CPAP did not control hypoventilation periods. Mechanical ventilation was initiated with negative pressure (NPV) through a poncho. The patient presented severe discomfort with NPV and obstructive apneas were verified during it. She refused to continue NPV. Mechanical ventilation was initiated with positive intermittent pressure (IPPV) through a nasal mask. The patient had excellent tolerance to the procedure. SpO2 during IPPV was always higher than 95%. During sleep induction (under IPPV), respiration in phase with the ventilator 1: 1 was observed; instead, during consolidated sleep there was a complete dependence of the ventilator with apnea for over 2 min when IPPV was interrupted (Fig. 1). After 2 months of treatment, a relief of right ventricular failure occurred and hematocrit fell to 39%. There was an improvement of day-time ABG (Table I). The P. 0.1/PaCO2 curve 3 months after IPPV was the same as the previous one (Fig. 2). The patient has been for 18 months on home ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Hipoventilacion alveolar central con cor pulmonale: tratamiento exitoso mediante ventilacion con presion positiva intermitente no invasiva / Central alveolar hypoventilation with cor pulmonale: successful treatment by non-invasive intermittent positive pressure ventilation

Una paciente de 62 años con atecedentes de PCC bilateral, presentó 2 años después de la remoción del derecho signos de insuficiencia cardíaca derecha. Se comprobó hipoxemia, hipercapnia e hipertensión pulmonar con volúmenes pulmonares normales. Por la ausencia de respuesta ventilatoria a la hipoxia y la hipercapnia provocadas, a la prolongación del tiempo de apnea voluntaria y la corrección de la hipercapnia por hiperventilación voluntaria se hizo diagnóstico de hipoventilación alveolar central. El tratamiento con progesterona (200 mg/d durante 3 semanas) y naloxona no mejoró los gases en sangre o la curva PO.1/PaCO2. Acetazolamida (250 mg/d) produjo acidosis respiratoria. La aplicación de CPAP nasal no controló los períodos de hipoventilación. Se inició ventilación mecánica con presión negativa (NPV) a través de un proncho. La paciente presentó severo disconfort con NPV y se verificaron apneas obstructivas durante su uso. La paciente se negó a continuar recibiendo NPV. Se inició ventilación mecánica con presión positiva intermitente (IPPV) a través de máscara nasal. La paciente tuvo excelente tolerancia al procedimiento. La SaO2 durante IPPV fue siempre superior a 95 por ciento. Durante el período de inducción del sueño (bajo IPPV) se observó respiración enfase con el ventilador 1: 1, en cambio durante el sueño consolidado, había dependencia completa del respirador con apnea de más de 2 min al interrumpir la IPPV. Después de 2 meses de tratamiento la paciente presentó desaparición de los signos de falla ventricular derecha y descenso del hematocrito a 39 por ciento...

Hipoventilación alveolar central con cor pulmonale: tratamiento exitoso mediante ventilación con presión positiva intermitente no invasiva. / [Central alveolar hypoventilation with cor pulmonale: successful treatment by non-invasive intermittent positive pressure ventilation]

A 62 year-old woman with a bilateral carotid body paraganglioma presented, 2 years after the removal of the right one, with signs of right-heart failure. Hypoxemia, hypercapnia, polycythemia and pulmonary hypertension with normal ventilatory capacity were found. Central alveolar hypoventilation was diagnosed on the basis of absence of ventilatory response and sensation of provoked hypercapnia, prolonged breath-holding time and correction of hypercapnia by voluntary ventilation. Progesterone (200 mg/d during 3 weeks) or naloxone did not improve either arterial blood gases (ABG) or the P 0.1/PCO2 curve. Hypoxemia and hypercapnia were not corrected during metabolic acidosis provoked by acetazolamide (250 mg/d). Nasal CPAP did not control hypoventilation periods. Mechanical ventilation was initiated with negative pressure (NPV) through a poncho. The patient presented severe discomfort with NPV and obstructive apneas were verified during it. She refused to continue NPV. Mechanical ventilation was initiated with positive intermittent pressure (IPPV) through a nasal mask. The patient had excellent tolerance to the procedure. SpO2 during IPPV was always higher than 95

. During sleep induction (under IPPV), respiration in phase with the ventilator 1: 1 was observed; instead, during consolidated sleep there was a complete dependence of the ventilator with apnea for over 2 min when IPPV was interrupted (Fig. 1). After 2 months of treatment, a relief of right ventricular failure occurred and hematocrit fell to 39

. There was an improvement of day-time ABG (Table I). The P. 0.1/PaCO2 curve 3 months after IPPV was the same as the previous one (Fig. 2). The patient has been for 18 months on home ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Hipoventilacion alveolar central con cor pulmonale: tratamiento exitoso mediante ventilacion con presion positiva intermitente no invasiva / Central alveolar hypoventilation with cor pulmonale: successful treatment by non-invasive intermittent positive pressure ventilation

Una paciente de 62 años con atecedentes de PCC bilateral, presentó 2 años después de la remoción del derecho signos de insuficiencia cardíaca derecha. Se comprobó hipoxemia, hipercapnia e hipertensión pulmonar con volúmenes pulmonares normales. Por la ausencia de respuesta ventilatoria a la hipoxia y la hipercapnia provocadas, a la prolongación del tiempo de apnea voluntaria y la corrección de la hipercapnia por hiperventilación voluntaria se hizo diagnóstico de hipoventilación alveolar central. El tratamiento con progesterona (200 mg/d durante 3 semanas) y naloxona no mejoró los gases en sangre o la curva PO.1/PaCO2. Acetazolamida (250 mg/d) produjo acidosis respiratoria. La aplicación de CPAP nasal no controló los períodos de hipoventilación. Se inició ventilación mecánica con presión negativa (NPV) a través de un proncho. La paciente presentó severo disconfort con NPV y se verificaron apneas obstructivas durante su uso. La paciente se negó a continuar recibiendo NPV. Se inició ventilación mecánica con presión positiva intermitente (IPPV) a través de máscara nasal. La paciente tuvo excelente tolerancia al procedimiento. La SaO2 durante IPPV fue siempre superior a 95 por ciento. Durante el período de inducción del sueño (bajo IPPV) se observó respiración enfase con el ventilador 1: 1, en cambio durante el sueño consolidado, había dependencia completa del respirador con apnea de más de 2 min al interrumpir la IPPV. Después de 2 meses de tratamiento la paciente presentó desaparición de los signos de falla ventricular derecha y descenso del hematocrito a 39 por ciento...(AU)

Central and peripheral diaphragmatic fatigue in loaded normal and vagotomized dogs.

Severe inspiratory elastic load terminated by respiratory arrest (RA) was studied in 24 anesthetized dogs (group 1, normal: n = 14; group 2, vagotomized: n = 10). The peripheral and central components of the decrease in diaphragmatic force generation and the events preceding RA were studied. We measured stimulated tetanic transdiaphragmatic pressure (Pdi), single twitch compound action potentials, integrated diaphragmatic electromyographic activity (iEMGdi), respiratory frequency (f), inspiratory time, inspiratory drive, overall diaphragmatic activation, and Pdi single twitch superimposed over peak Pdi. Imposed target pressure was -68.8 +/- 4.37 cmH2O for group 1 and -70.9 +/- 4.19 cmH2O for group 2, and the tension-time index of the diaphragm was the same for both groups (0.22 +/- 0.010). During load, 1) f increased in group 1 from 25.4 +/- 1.33 to 41.3 +/- 4.66 cycles/min, and tachypnea was prevented by vagotomy; 2) twitch occlusion persisted until RA and compound action potentials did not change; 3) iEMGdi and inspiratory drive increased and remained high until RA; 4) overall diaphragmatic activation increased 514 (group 1) and 260% (group 2) and then decreased to 228% of the basal value 10 s before RA in group 1 because of a fall in f; and 5) after RA, Pdi stimulated at 60 Hz fell to 39 (group 1; P < 0.0025) and 51% (group 2; NS with group 1) of the basal value. In summary, 1) peripheral fatigue developed without transmission failure; 2) diaphragmatic activation remained maximal until RA; 3) the fall in f appeared as a preterminal event only in group 1; and 4) vagus nerves are necessary for load-induced tachypnea.

[Causes of CO2 retention in patients with chronic obstructive lung disease]. / Causas de retención de CO2 en pacientes con neumopatía obstructiva crónica.

The mechanisms of chronic ventilatory failure in chronic obstructive pulmonary disease are complex. This paper analyses the diverse available information: mechanical factors and gas-exchange, fighter vs. non-fighter, the ventilatory pattern theory and the fatigue threshold theory. Finally we comment on the evidence supporting the new concept that hypercapnia may develop to avoid or prevent fatigue. Indeed, it is very likely that chronic CO2 retention in COPD may develop by mechanical disadvantages of the inspiratory muscles rather than impairment of ventilation-perfusion ratios. This opens a fascinating new research line on the neuromechanical control of breathing. When the respiratory effort is approaching the fatigue level, the respiratory muscles may elicit a negative feedback reflex, the muscle activity is depressed and hypercapnia develops. If this is so, chronic hypercapnia may be an index of imminent fatigue if increases in ventilation or work of breathing are required. Under this condition some degree of central diaphragm fatigue may help to protect the muscle from severe or limiting peripheral fatigue or even muscle injury. Finally, we comment on some therapeutic approaches such as ventilatory stimulants, training, rest and, specially, oxygen administration and the mechanisms involved in the PCO2 increases.

Causas de retención de CO2 en pacientes con neumopatía obstructiva crónica. / [Causes of CO2 retention in patients with chronic obstructive lung disease]

The mechanisms of chronic ventilatory failure in chronic obstructive pulmonary disease are complex. This paper analyses the diverse available information: mechanical factors and gas-exchange, fighter vs. non-fighter, the ventilatory pattern theory and the fatigue threshold theory. Finally we comment on the evidence supporting the new concept that hypercapnia may develop to avoid or prevent fatigue. Indeed, it is very likely that chronic CO2 retention in COPD may develop by mechanical disadvantages of the inspiratory muscles rather than impairment of ventilation-perfusion ratios. This opens a fascinating new research line on the neuromechanical control of breathing. When the respiratory effort is approaching the fatigue level, the respiratory muscles may elicit a negative feedback reflex, the muscle activity is depressed and hypercapnia develops. If this is so, chronic hypercapnia may be an index of imminent fatigue if increases in ventilation or work of breathing are required. Under this condition some degree of central diaphragm fatigue may help to protect the muscle from severe or limiting peripheral fatigue or even muscle injury. Finally, we comment on some therapeutic approaches such as ventilatory stimulants, training, rest and, specially, oxygen administration and the mechanisms involved in the PCO2 increases.

[Diaphragmatic reserve strength in obese patients]. / Reserva de fuerza del diafragma en pacientes obesos.

Nine obese patients (OB) and seven normal subjects (N) were studied in order to determine diaphragmatic strength reserve, measured in terms of diaphragm Tension/Time Index (TTdi). This index was measured with the patients awake and during the obstructive apnea (OA) episodes. TTdi was 2.7 times superior in the OB (p < 0.0005) and was related with a lower Pdi Max (102 vs 202 cm H2O; p < 0.005) and with a higher Pdi (9 vs 6 cm H2O; p < 0.05). During OA the TTdi was higher than the threshold value to develop diaphragmatic fatigue (0.15-0.20) in three patients. This value was not exceeded in one patient because of striking paradoxical diaphragmatic movements. As for anthropometric data, DPI% range was higher and wider in OB (Table 1). The pCO2 in OB was 40 +/- 6 mmHg. In all patients (Table 3), severe hypoxia and hypercapnial were observed. TTdi evolution in an OA in 4 patients can be appreciated in Figure 3. It can be concluded that the diaphragmatic strength reserve is reduced in OB so that they are more susceptible to develop diaphragmatic fatigue. A fatigant respiratory pattern was also registered during the OA.

Reserva de fuerza del diafragma en pacientes obesos. / [Diaphragmatic reserve strength in obese patients]

Nine obese patients (OB) and seven normal subjects (N) were studied in order to determine diaphragmatic strength reserve, measured in terms of diaphragm Tension/Time Index (TTdi). This index was measured with the patients awake and during the obstructive apnea (OA) episodes. TTdi was 2.7 times superior in the OB (p < 0.0005) and was related with a lower Pdi Max (102 vs 202 cm H2O; p < 0.005) and with a higher Pdi (9 vs 6 cm H2O; p < 0.05). During OA the TTdi was higher than the threshold value to develop diaphragmatic fatigue (0.15-0.20) in three patients. This value was not exceeded in one patient because of striking paradoxical diaphragmatic movements. As for anthropometric data, DPI

range was higher and wider in OB (Table 1). The pCO2 in OB was 40 +/- 6 mmHg. In all patients (Table 3), severe hypoxia and hypercapnial were observed. TTdi evolution in an OA in 4 patients can be appreciated in Figure 3. It can be concluded that the diaphragmatic strength reserve is reduced in OB so that they are more susceptible to develop diaphragmatic fatigue. A fatigant respiratory pattern was also registered during the OA.