Increasing ventilator surge capacity in COVID 19 pandemic: design, manufacture and in vitro-in vivo testing in anaesthetized healthy pigs of a rapid prototyped mechanical ventilator.

OBJECTIVE: The advent of new technologies has made it possible to explore alternative ventilator manufacturing to meet the worldwide shortfall for mechanical ventilators especially in pandemics. We describe a method using rapid prototyping technologies to create an electro-mechanical ventilator in a cost effective, timely manner and provide results of testing using an in vitro-in vivo testing model. RESULTS: Rapid prototyping technologies (3D printing and 2D cutting) were used to create a modular ventilator. The artificial manual breathing unit (AMBU) bag connected to wall oxygen source using a flow meter was used as air reservoir. Controlled variables include respiratory rate, tidal volume and inspiratory: expiratory (I:E) ratio. In vitro testing and In vivo testing in the pig model demonstrated comparable mechanical efficiency of the test ventilator to that of standard ventilator but showed the material limits of 3D printed gears. Improved gear design resulted in better ventilator durability whilst reducing manufacturing time (< 2-h). The entire cost of manufacture of ventilator was estimated at 300 Australian dollars. A cost-effective novel rapid prototyped ventilator for use in patients with respiratory failure was developed in < 2-h and was effective in anesthetized, healthy pig model.

Esclerosis lateral amiotrófica: valoración del fracaso muscular inspiratorio / Amyotrophic Lateral Sclerosis: The Assessment of Inspiratory Muscle Failure

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La monitorización convencional no es suficiente para valorar el esfuerzo respiratorio durante la ventilación asistida / Conventional monitoring is not sufficient to assess respiratory effort during assisted ventilation

Objetivo: Analizar la relación y concordancia entre el esfuerzo respiratorio calculado con las señales del respirador (Pmus) y el medido con presión esofágica (Pes), en ventilación mecánica con diferentes niveles de asistencia respiratoria. Diseño: Estudio prospectivo de una cohorte. Ámbito: Unidad de cuidados intensivos polivalente en 2 hospitales terciarios. Pacientes: Pacientes en fase de retirada de la ventilación mecánica. Intervenciones: La presión en la vía aérea, esofágica y flujo respiratorio se registraron en CPAP, ventilación asistida controlada por volumen (ACV) y presión soporte (PS) con asistencia respiratoria completa (ACV1, PS1) y parcial (ACV5, PS5). Variables medidas en Pes y Pmus: amplitud respiratoria (Δ: cmH2O) y el producto presión tiempo por minuto (PTPm: cmH2O·s/m). Resultados: En 10 pacientes se estudiaron 41 registros. La asistencia en CPAP fue de 5cmH2O, PS1 15±5 y PS59±4cmH2O. En ACV1 el flujo inspiratorio fue 1±0,2l/s, reducido a 0,49±0,1l/s para ACV5. El esfuerzo respiratorio disminuyó con el aumento de la asistencia respiratoria: ΔPes (CPAP, ACV5, ACV1, PS5, PS1): 11±3, 6±3, 5±3, 9±6, 7±7 y en ΔPmus 16±5, 10±6, 5±3, 10±6, 5±4cmH2O (p<0,001). PTPm Pes: 213±87, 96±91, 23±24, 206±121, 108±100 (p=0,001) y en Pmus: 293±117, 156±84, 24±32, 233±121, 79±90cmH2O·s/m (p<0,001). Las medidas en Pes y Pmus mostraron una correlación Δ:0,72 y PTPm: 0,87. El análisis de Bland-Altman demostró que la diferencia ΔPes-Pmus puede ser de 16cmH2O y el PTPm de 264 y el error sistemático en Δ: −0,98±4,4 y PTPm −23,69±66,3cmH2O·s/m. Conclusiones: Los parámetros calculados de esfuerzo respiratorio y los medidos directamente presentan diferencias que no son aceptables en la práctica clínica

Objective: Study the relationship and concordance between calculated respiratory effort using the signals of the ventilator (Pmus) and that measured in esophageal pressure (Pes) on mechanical ventilation with different levels of respiratory assistance. Design: Prospective cohort study. Ambit: Intensive Care Unit of 2 universitary hospitals. Patients Patients on weaning time. Procedure: Airway, esophageal and respiratory flow were recorded on CPAP, assist volume control (ACV) and pressure support (PS), with complete (ACV1,PS1) and partial assistance (ACV5,PS5). Measurement: respiratory variations of Pes and Pmus (Δ: cmH2O) and pressure time product (PTPm: cmH2O·s/m). Results: Fourty one records were studied, the assistance was in CPAP of 5cmH2O, PS1 of 15±5 reduced to 9±4cmH2O. In ACV1 the inspiratory flow was 1±0.2l/s, reduced to 0.49±0.1l/s for ACV5. The increase in respiratory assistance decreases respiratory effort, measured in Delta Pes (CPAP, ACV5, ACV1, PS5, PS1): 11±3, 6±3, 5±3, 9±6, 7±7 and in Pmus 16±5, 10±6, 5±3, 10±6, 5±4cmH2O (P<.001). The PTP per minute measured in Pes: 213±87, 96±91, 23±24, 206±121, 108±100 (P=.001) and in Pmus: 293±117, 156±84, 24±32, 233±121, 79±90 (P<.001). The measurements in Pes and Pmus showed the following correlation, in Delta: 0.72 and PTPm, 0.87. The Bland-Altman analysis indicates that the difference between Delta Pes-Pmus can be 16 and the PTPm of 264 and the systematic error in Delta: −0.98±4.4 and PTPm −23.69±66.3cmH2O·s/m. Conclusions: Calculated and measured parameters of respiratory effort showed unacceptable differences in clinical practice

Exertional dyspnea and operating lung volumes in asthma.

Dyspnea has been reported to be a main contributor to exercise avoidance in asthma. While traditional markers of ventilation do not explain the heightened dyspnea during exercise in patients with asthma, this study proposed that exertional dyspnea in asthma was due to high-operating lung volumes, which may be improved with a short-acting ß2-agonist. On two separate days, 16 patients with asthma and 16 controls completed a lung function test and incremental exercise tests to exhaustion. On one of the days (order randomized), 400 µg salbutamol was administered before exercise. Inspiratory capacity (IC), inspiratory reserve volume (IRV), and dyspnea (modified Borg scale) were evaluated throughout exercise. Compared with controls, patients with asthma reported greater dyspnea at the same absolute submaximal workloads. Furthermore, patients with asthma demonstrated altered breathing responses to exercise, characterized by reduced IC and IRV throughout exercise compared with controls. The reduced IRV was associated with increased dyspnea in patients with asthma. Salbutamol did not affect dyspnea or operating lung volumes in either group. The increased perception of dyspnea during incremental exercise in patients with asthma appears to be secondary to a reduction in IRV, which is unaffected by an inhaled ß2-agonist. NEW & NOTEWORTHY Increased exertional dyspnea in asthma appears to be due to high operating lung volumes and is not affected by salbutamol.

Treatment effect of idebenone on inspiratory function in patients with Duchenne muscular dystrophy.

Assessment of dynamic inspiratory function may provide valuable information about the degree and progression of pulmonary involvement in patients with Duchenne muscular dystrophy (DMD). The aims of this study were to characterize inspiratory function and to assess the efficacy of idebenone on this pulmonary function outcome in a large and well-characterized cohort of 10-18 year-old DMD patients not taking glucocorticoid steroids (GCs) enrolled in the phase 3 randomized controlled DELOS trial. We evaluated the effect of idebenone on the highest flow generated during an inspiratory FVC maneuver (maximum inspiratory flow; V'I,max(FVC)) and the ratio between the largest inspiratory flow during tidal breathing (tidal inspiratory flow; V'I,max(t)) and the V'I,max(FVC). The fraction of the maximum flow that is not used during tidal breathing has been termed inspiratory flow reserve (IFR). DMD patients in both treatment groups of DELOS (idebenone, n = 31; placebo: n = 33) had comparable and abnormally low V'I,max(FVC) at baseline. During the study period, V'I,max(FVC) further declined by -0.29 L/sec in patients on placebo (95%CI: -0.51, -0.08; P = 0.008 at week 52), whereas it remained stable in patients on idebenone (change from baseline to week 52: 0.01 L/sec; 95%CI: -0.22, 0.24; P = 0.950). The between-group difference favoring idebenone was 0.27 L/sec (P = 0.043) at week 26 and 0.30 L/sec (P = 0.061) at week 52. In addition, during the study period, IFR improved by 2.8% in patients receiving idebenone and worsened by -3.0% among patients on placebo (between-group difference 5.8% at week 52; P = 0.040). Although the clinical interpretation of these data is currently limited due to the scarcity of routine clinical practice experience with dynamic inspiratory function outcomes in DMD, these findings from a randomized controlled study nevertheless suggest that idebenone preserved inspiratory muscle function as assessed by V'I,max(FVC) and IFR in patients with DMD. Pediatr Pulmonol. 2017;52:508-515. © 2016 The Authors. Pediatric Pulmonology Published by Wiley Periodicals, Inc.

Abdominal Muscle Activity during Mechanical Ventilation Increases Lung Injury in Severe Acute Respiratory Distress Syndrome.

OBJECTIVE: It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. METHODS: Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35-60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. RESULTS: For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). CONCLUSION: Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury.

APPLICATION OF LAPAROSCOPIC LIFTING SYSTEMS IN PATIENTS WITH HIGH CARDIORESPIRATORY RISK.

Intra-abdominal hypertension during laparoscopic operations increased the risk of complications from cardiovascular and respiratory systems. An application of laparolifting systems allowed doctors to avoid changes of pneumoperitoneum, although it was associated with technical difficulties in operation performance. The authors used a test in order to determine cardiorespiratory reserve in preoperative period. The reserve was characterized by decrease of stroke volume of the heart against the background of intra-abdominal hypertension. There was noted a reliable increase of complication rate in these patients in case of application of standard laparoscopic operation compared with operation using lifting systems.

Work of Breathing into Snow in the Presence versus Absence of an Artificial Air Pocket Affects Hypoxia and Hypercapnia of a Victim Covered with Avalanche Snow: A Randomized Double Blind Crossover Study.

Presence of an air pocket and its size play an important role in survival of victims buried in the avalanche snow. Even small air pockets facilitate breathing. We hypothesize that the size of the air pocket significantly affects the airflow resistance and work of breathing. The aims of the study are (1) to investigate the effect of the presence of an air pocket on gas exchange and work of breathing in subjects breathing into the simulated avalanche snow and (2) to test whether it is possible to breathe with no air pocket. The prospective interventional double-blinded study involved 12 male volunteers, from which 10 completed the whole protocol. Each volunteer underwent two phases of the experiment in a random order: phase "AP"--breathing into the snow with a one-liter air pocket, and phase "NP"--breathing into the snow with no air pocket. Physiological parameters, fractions of oxygen and carbon dioxide in the airways and work of breathing expressed as pressure-time product were recorded continuously. The main finding of the study is that it is possible to breath in the avalanche snow even with no air pocket (0 L volume), but breathing under this condition is associated with significantly increased work of breathing. The significant differences were initially observed for end-tidal values of the respiratory gases (EtO2 and EtCO2) and peripheral oxygen saturation (SpO2) between AP and NP phases, whereas significant differences in inspiratory fractions occurred much later (for FIO2) or never (for FICO2). The limiting factor in no air pocket conditions is excessive increase in work of breathing that induces increase in metabolism accompanied by higher oxygen consumption and carbon dioxide production. The presence of even a small air pocket reduces significantly the work of breathing.

Correlated variability in the breathing pattern and end-expiratory lung volumes in conscious humans.

In order to characterize the variability and correlation properties of spontaneous breathing in humans, the breathing pattern of 16 seated healthy subjects was studied during 40 min of quiet breathing using opto-electronic plethysmography, a contactless technology that measures total and compartmental chest wall volumes without interfering with the subjects breathing. From these signals, tidal volume (VT), respiratory time (TTOT) and the other breathing pattern parameters were computed breath-by-breath together with the end-expiratory total and compartmental (pulmonary rib cage and abdomen) chest wall volume changes. The correlation properties of these variables were quantified by detrended fluctuation analysis, computing the scaling exponenta. VT, TTOT and the other breathing pattern variables showed α values between 0.60 (for minute ventilation) to 0.71 (for respiratory rate), all significantly lower than the ones obtained for end-expiratory volumes, that ranged between 1.05 (for rib cage) and 1.13 (for abdomen) with no significant differences between compartments. The much stronger long-range correlations of the end expiratory volumes were interpreted by a neuromechanical network model consisting of five neuron groups in the brain respiratory center coupled with the mechanical properties of the respiratory system modeled as a simple Kelvin body. The model-based α for VT is 0.57, similar to the experimental data. While the α for TTOT was slightly lower than the experimental values, the model correctly predicted α for end-expiratory lung volumes (1.045). In conclusion, we propose that the correlations in the timing and amplitude of the physiological variables originate from the brain with the exception of end-expiratory lung volume, which shows the strongest correlations largely due to the contribution of the viscoelastic properties of the tissues. This cycle-by-cycle variability may have a significant impact on the functioning of adherent cells in the respiratory system.

Los ejercicios respiratorios y el IMC en estudiantes de 12 - 13 años de secundaria de la I.E. Nicolás Copérnico Lima - San Juan de Lurigancho - diciembre 2014 / Breathing exercises and BMI in students 12 to 13 years of high school at the I.E. Nicolas Copernico. Lima - San Juan de Lurigancho - December 2014

Introducción: La Encuesta Nacional de Nutrición y Salud (ENNSA) del 2010 menciona que el IMC en los adolescente de 15 años se encontró que el 33,78 por ciento de los escolares evaluados se encuentran en condición de obesidad, el 32,45 por ciento en condición normal, el 23,84 por ciento en condición de sobrepeso, un 5,96 por ciento en condición delgadez y el 3,97 por ciento en condición de riesgo de delgadez, otros estudios destacan un gran aumento del sobre peso y obesidad en niños y adolescentes de diversas regiones del mundo inclusive en el Perú. Los efectos del sobrepeso y la obesidad abarcan alteraciones hormonales, metabólicas, ortopédicas y psicológicas, como consecuencia de este conjunto de anomalías el trabajo ventilatorio se altera teniendo la necesidad de una intervención precoz de la Fisioterapia, no hay estudios que muestren trabajos de fisioterapia a través de ejercicios respiratorios en adolescente. Objetivo: Determinar la relación de los ejercicios respiratorios y el IMC en estudiantes de 12-13 años de secundaria de la I.E. “Nicolás Copérnico” Lima-San Juan de Lurigancho-Diciembre 2014. Diseño: Diseño de estudio experimental de subtipo cuasiexperimental. Institución: Escuela Académico Profesional de Tecnología Médica Terapia Física y Rehabilitación Facultad de Medicina San Fernando, Universidad Nacional Mayor de San Marcos. Participantes: La muestra está constituida por 116 alumnos de 12 a 13 años de la I.E. “Nicolás Copérnico” Lima-San Juan de Lurigancho, seleccionados a través del método de muestreo no probabilísticos del tipo casual o incidental. Intervenciones: Se aplicó el plan de tratamiento de entrenamiento muscular respiratorio para niños de 12-13 años de la I.E. “Nicolás Copérnico” SJL. Resultados: Según la variación del volumen de inspiración máxima antes y después del programa de ejercicios respiratorios encontramos que ha predominado la condición de MANTENER el volumen de inspiración máxima sostenida en el grupo de DELGADEZ un...

Introduction: The National Health and Nutrition Survey (ENNSA) of 2010 mentions that the BMI of 15 year old was found that 33.78 per cent of students are evaluated on condition of obesity, 32.45 per cent in normal condition, 23.84 per cent in the overweight condition, 5.96 per cent in thin condition and 3.97 per cent at Risk of thinness, other studies highlight a big increase in overweight and obesity in children and adolescents from different regions of the world including in Peru. The effects of overweight and obesity include hormonal, metabolic, orthopedic and psychological disorders as a result of this set of anomalies altered ventilatory work having the need for early intervention of physiotherapy, no studies showing physiotherapy jobs through breathing exercises teenager. Objective: To determine the positive relationship of breathing exercises and the body mass index in students 12-13 years of I.E. “Nicolas Copernico” Lima-San Juan de Lurigancho-December 2014. Design: Design of experimental study of cuasiexperimental subtype. Institution: Academic Professional School of Medical Technology Physical Therapy and Rehabilitation Medicine Faculty of San Fernando, Mayor de San Marcos National University. Participants: The sample consists of 116 students 12-13 years of I.E. “Nicolas Copernico” Lima-San Juan de Lurigancho, selected through non-probability sampling method of casual or incidental type. Interventions: The treatment plan respiratory muscle training for children 12-13 years of I.E. “Nicolas Copernico” SJL. Results: According to the change in volume of high before inspiration and after breathing exercise program found that has dominated the condition KEEP volume maximum sustained inspiration in the group THINNESS 68 per cent in the NORMAL group to 73 per cent in the group OVERWEIGHT 68 per cent on condition of and in the group of obesity by 56 per cent, Conclusions: In the study it is concluded that there is no positive relationship of breathing...

Differences in the peak cough flow among stroke patients with and without dysphagia.

Coughing is an important protective mechanism for keeping the airway clear, and adequate voluntary coughing reduces the risk of aspiration in patients with deglutition disorders. The purpose of this study was to compare the peak cough flow (PCF) of stroke patients with and without dysphagia and to identify the physical and respiratory determinants of PCF.Using a spirometer, we measured and compared the PCFs of 10 stroke patients with dysphagia (SPD), 20 stroke patients without dysphagia (SP) and 10 gender and age matched healthy controls (HC) recruited by using a notice at a clinic and in newspapers. The PCF of the SPD (mean ± SD, 160.1 ± 68.7 l/min) was significantly lower than that of the SP and HC (297.2 ± 114.2 l/min and 462.0 ± 84.4 l/min, respectively; one-way ANOVA, Scheffe's test, P < 0.05). The vital capacity (VC) and inspiratory reserve volume (IRV) of the SPD were lower than those of the HC. Stepwise multivariate regression analysis revealed that IRV and ambulation function (Functional Ambulation Categories, FAC) contributed 50% and 17% to the variance of PCF (P < 0.05), respectively. It is suggested that respiratory function, especially IRV, is important for maintaining PCF in SPD.

Regional ventilation distribution in the first 6 months of life.

Electrical impedance tomography (EIT) has been used to study regional ventilation distribution in neonatal and paediatric lung disease; however, little information has been obtained in healthy newborns and infants. Data on regional ventilation distribution and regional filling characteristics were obtained using EIT in the neonatal period, at 3 and 6 months of age, in spontaneously breathing infants during non-rapid eye movement sleep. Regional ventilation distribution was described using regional end-expiratory and end-inspiratory impedance amplitudes, and geometric centre of ventilation. Regional filling characteristics were described with the phase lag or lead of the regional impedance change in comparison to global impedance change. 32 infants were measured in the supine position. Regional impedance amplitudes increased with age but regional ventilation distribution remained unchanged in all infants at any age, with the dependent (posterior) lung always better ventilated. Regional filling characteristics showed that the dependent lung filled during inspiration before the nondependent lung during all follow-up measurements. Regional ventilation distribution and regional filling characteristics remained unchanged over the first 6 months of life, and the results obtained on regional ventilation distribution are very similar to those in adult subjects.

Impact of a rehabilitation program on dyspnea intensity and quality in patients with chronic obstructive pulmonary disease.

BACKGROUND: It has yet to be determined whether the language of dyspnea responds to pulmonary rehabilitation programs (PRP). OBJECTIVE: We tested the hypothesis that PRP affect both the intensity and quality of exercise-induced dyspnea in patients with chronic obstructive pulmonary disease (COPD). METHODS: We studied 49 patients equipped with a portable telemetric spiroergometry device during the 6-min walking test before and 4 weeks after PRP. In a first screening visit, appropriate verbal descriptors of dyspnea were chosen that patients were familiar with during daily living activities. Tidal volume, respiratory frequency, inspiratory capacity, inspiratory reserve volume (IRV) and dyspnea intensity were evaluated by a modified Borg scale every minute during the test. RESULTS: Qualitative descriptors of dyspnea were defined by three different sets of cluster descriptors (a-c) at the end of the exercise test, before and after PRP: a - work/effort (W/E); b - inspiratory difficulty (ID) and chest tightness (CT), and c - W/E, ID and/or CT. The three language subgroups exhibited similar lung function at baseline, and similar rating of dyspnea and ventilatory changes during exercise. The rehabilitation program shifted the Borg-IRV relationship (less Borg at any given IRV) towards the right without modifying the set of descriptors in most patients. CONCLUSIONS: Rehabilitation programs allowed patients to tolerate a greater amount of restrictive dynamic ventilatory defect by modifying the intensity, but not necessarily the quality of dyspnea.

Effect of hormone replacement on exercise cardiopulmonary reserve and recovery performance in subclinical hypothyroidism.

Subclinical hypothyroidism (SH) patients present cardiopulmonary, vascular and muscle dysfunction, but there is no consensus about the benefits of levothyroxine (L-T4) intervention on cardiopulmonary performance during exercise. The aim of the present study was to investigate the effects of L-T4 on cardiopulmonary exercise reserve and recovery in SH patients. Twenty-three SH women, 44 (40-50) years old, were submitted to two ergospirometry tests, with an interval of 6 months of normalization of thyroid-stimulating hormone (TSH) levels (L-T4 replacement group) or simple observation (TSH = 6.90 µIU/mL; L-T4 = 1.02 ng/dL). Patients with TSH >10 µIU/mL were excluded from the study to assure that they would receive treatment in this later stage of SH. Twenty 30- to 57-year-old women with no thyroid dysfunction (TSH = 1.38 µIU/mL; L-T4 = 1.18 ng/dL) were also evaluated. At baseline, lower values of gas exchange ratio reserve (0.24 vs 0.30; P < 0.05) were found for SH patients. The treated group presented greater variation than the untreated group for pulmonary ventilation reserve (20.45 to 21.60 L/min; median variation = 5.2 vs 25.09 to 22.45 L/min; median variation = -4.75, respectively) and for gas exchange ratio reserve (0.19 to 0.27; median variation = 0.06 vs 0.28 to 0.18; median variation = -0.08, respectively). There were no relevant differences in cardiopulmonary recovery for either group at baseline or after follow-up. In the sample studied, L-T4 replacement improved exercise cardiopulmonary reserve, but no modification was found in recovery performance after exercise during this period of analysis.

Effect of hormone replacement on exercise cardiopulmonary reserve and recovery performance in subclinical hypothyroidism

Subclinical hypothyroidism (SH) patients present cardiopulmonary, vascular and muscle dysfunction, but there is no consensus about the benefits of levothyroxine (L-T4) intervention on cardiopulmonary performance during exercise. The aim of the present study was to investigate the effects of L-T4 on cardiopulmonary exercise reserve and recovery in SH patients. Twenty-three SH women, 44 (40-50) years old, were submitted to two ergospirometry tests, with an interval of 6 months of normalization of thyroid-stimulating hormone (TSH) levels (L-T4 replacement group) or simple observation (TSH = 6.90 μIU/mL; L-T4 = 1.02 ng/dL). Patients with TSH >10 μIU/mL were excluded from the study to assure that they would receive treatment in this later stage of SH. Twenty 30- to 57-year-old women with no thyroid dysfunction (TSH = 1.38 μIU/mL; L-T4 = 1.18 ng/dL) were also evaluated. At baseline, lower values of gas exchange ratio reserve (0.24 vs 0.30; P < 0.05) were found for SH patients. The treated group presented greater variation than the untreated group for pulmonary ventilation reserve (20.45 to 21.60 L/min; median variation = 5.2 vs 25.09 to 22.45 L/min; median variation = -4.75, respectively) and for gas exchange ratio reserve (0.19 to 0.27; median variation = 0.06 vs 0.28 to 0.18; median variation = -0.08, respectively). There were no relevant differences in cardiopulmonary recovery for either group at baseline or after follow-up. In the sample studied, L-T4 replacement improved exercise cardiopulmonary reserve, but no modification was found in recovery performance after exercise during this period of analysis.

Respiratory muscle strength in pregnancy.

BACKGROUND: Muscle respiratory strength studies during pregnancy are very scarce. The aim of this paper is to describe maximum inspiratory (PImax) and expiratory (PEmax) mean pressure values in women during their first pregnancy and to determine the relationship between the anthropometric, morphologic and physiologic variables of these pressures. METHODS: One hundred and twenty women (120) primigravidas were studied from the 5th to 40th gestational week, ages ranging from 20 to 29 years old, euthrophic and with low risk pregnancies. RESULTS: PImax and PEmax mean values were 88.5 ± 16.52 cmH(2)O and 99.76 ± 18.19 cmH(2)O respectively. There was no association between gestational age and PImax (r = -0.06; p = 0.49) or PEmax (r = -0.11; p = 0.22). There was also no difference between PImax and PEmax during pregnancy trimesters and no correlation between pregnancy age and the pressures in each trimester. Height was the only anthropometric variable indicating a significant PImax (r = 0.20; p = 0.02) association. Fundal uterus height and inter-recti abdominis distance were not associated to respiratory pressure values. PEmax is not associated with the group of predictor variables (p = 0.127) and PImax demonstrated an independent association with height and dyspnea during physical exertion reflected by the following equation: PImax = 0.6 + 57.9 height - 1.68 dyspnea under effort. The present study suggests that inspiratory and expiratory maximum pressure values are not altered during different stages of pregnancy, however longitudinal studies are needed to assess changes over time.

Disfunción autonómica en pacientes con enfermedad pulmonar obstructiva crónica: efectos del entrenamiento sobre la recuperación de la frecuencia cardiaca / Autonomic dysfunction in patients with chronic obstructive pulmonary disease: Effects of training on heart rate recovery

Introducción: La recuperación de la frecuencia cardíaca (RFC) tras un esfuerzo máximo es un índice de función autonómica y se asocia con mayor mortalidad en algunas patologías. El objetivo de este estudio fue evaluar la prevalencia de disfunción autonómica en pacientes con enfermedad pulmonar obstructiva crónica (EPOC) estable y sus eventuales cambios con un programa de rehabilitación pulmonar. Pacientes y métodos: Estudio transversal de 68 pacientes con EPOC en fase estable (edad media: 71 años [DE: 8]), 65 hombres y 3 mujeres, volumen espiratorio forzado en el primer segundo (%) medio: 36,8 (DE: 11,9), incluidos en programa de entrenamiento aeróbico y de fuerza y resistencia (25 sesiones). Se realizó prueba de esfuerzo cardiopulmonar (PECP), prerrehabilitación en todos los pacientes. En un subgrupo de 12 se realizó, además, PECP posrehabilitación. Se evaluó la RFC en valores absolutos y categorizada tras claudicación en la PECP respecto a la frecuencia cardíaca pico (normalidad RFC>12). Resultados: Hubo 52 (76,5%) pacientes con alteración de la RFC (cambios<12lpm en el primer minuto de la recuperación). La RCF no se asoció con la severidad de la EPOC, la gasometría ni los valores de DLCO. En el subgrupo con PECP, el entrenamiento mejoró la RFC en 4 (80%) y la normalizó en 3 (50%). No se observaron complicaciones durante la rehabilitación en ninguno de los pacientes con disfunción autonómica. Conclusiones: La disfunción autonómica es muy prevalente en pacientes con EPOC estable independientemente de la severidad de la enfermedad, y su relevancia ha sido subestimada. La rehabilitación pulmonar es segura en estos pacientes y modifica el grado de esta disfunción autonómica con tendencia beneficiosa. Si la morbilidad y la supervivencia de los pacientes tienen relación con la disfunción autonómica también en nuestro medio merece ser evaluada (AU)

Introduction: Heart rate recovery (HRR) after maximal effort is an indicator of autonomic function and is related to mortality in different diseases. This study was aimed to estimate prevalence of autonomic dysfunction in patients with chronic obstructive pulmonary disease (COPD) and assess potential clinical effects of a pulmonary rehabilitation program (PRP). Patients and methods: Transversal study of 68 stable COPD patients (71±8 years; 65 men and 3 women; FEV1 36.8±11.9%) who received a PRP consisting of 5-week general and specific training (25 sessions). Cycle ergometry test (CET) was performed in all patients prior to the PRP. In a subset of 12 patients, CET was performed both previously and after rehabilitation. The primary end point was the prevalence of autonomic dysfunction as assessed by abnormal heart rate recovery in the first minute of recovery following a maximal symptom limited CET, and the potential changes following a normalised PRP. Results: A total of 52 (76.5%) patients showed abnormal HRR (i.e. change from peak exercise to first recovery minute <12bpm). HRR was not associated with the severity of COPD, arterial blood gases or DLCO values. The PRP induced significant changes in exercise capacity which was related to improvement of HRR in 4 (80%) and was normalised in 3 (50%). No complications or adverse effects were observed during rehabilitation. Conclusions Autonomic dysfunction is a highly prevalent impairment in COPD patients, irrespective the severity of the disease as assessed by conventional pulmonary function test. Relevance of autonomic dysfunction has been understimated in COPD. Pulmonary rehabilitation is safe and modifies the degree of autonomic dysfunction with potential benefits. The relatioship of morbidity and mortality with autonomic dysfunction in COPD in our setting remains to be evaluated (AU)

Natural orifice transluminal endoscopic surgery: cardiopulmonary safety of transesophageal mediastinoscopy.

BACKGROUND AND STUDY AIMS: Physiological reactions during natural orifice transluminal endoscopic surgery (NOTES) mediastinoscopy may lead to cardiorespiratory depression. The aim of the current study was to assess cardiopulmonary changes during transesophageal mediastinoscopy in an acute porcine model. METHODS: Transesophageal mediastinoscopy was performed under general anesthesia in eight female pigs with a bodyweight of 39 +/- 6 kg. Mediastinal access was achieved via a submucosal tunnel. The cardiac index and global end-diastolic volume index (reflecting preload) were measured every 3 minutes by transpulmonary thermodilution. The following parameters were also recorded: mediastinal pressure, heart rate, mean arterial pressure, systemic vascular resistance index (SVRI; reflecting afterload), peak inspiratory pressure, pH, pCO (2), and pO (2). RESULTS: In three animals, small tears in the parietal pleura resulted in tension pneumothoraces. The associated cardioplumonary deterioration was fatal in one pig. The other two pigs recovered after decompression with a chest tube. In the remaining five animals there were only mild hemodynamic and respiratory changes during mediastinoscopy. There was a significant ( P = 0.005) but minor transient fall in cardiac index, which correlated with a small rise in SVRI (r = - 0.857, P < 0.001). In the pigs with uncomplicated mediastinoscopy, on-demand insufflation via the endoscope resulted in median mediastinal pressures of 4.5 mm Hg (range 2.3 - 10.2 mm Hg). Overall, mediastinal and thoracic structures could be identified without difficulty via the transesophageal approach. CONCLUSIONS: NOTES mediastinoscopy carries a substantial risk of inadvertent development of a pneumothorax. Otherwise, it leads to negligible hemodynamic and pulmonary changes. In conclusion, close monitoring for the presence of a pneumothorax during NOTES mediastinoscopy appears to be mandatory.

Dynamic hyperinflation during daily activities: does COPD global initiative for chronic obstructive lung disease stage matter?

BACKGROUND: One of the contributors to exercise limitation in COPD is dynamic hyperinflation. Although dynamic hyperinflation appears to occur during several exercise protocols in COPD and seems to increase with increasing disease severity, it is unknown whether dynamic hyperinflation occurs at different severity stages according to the Global initiative for chronic Obstructive Lung Disease (GOLD) in daily life. The present study, therefore, aimed to compare dynamic hyperinflation between COPD GOLD stages II-IV during daily activities. METHODS: Thirty-two clinically stable patients with COPD GOLD II (n = 10), III (n = 12), and IV (n = 10) participated in this study. Respiratory physiology during a daily activity was measured at patients' homes with Oxycon Mobile. Inspiratory capacity maneuvers were performed at rest, at 2-min intervals during the activity, and at the end of the activity. Change in inspiratory capacity is commonly used to reflect change in end-expiratory lung volume (DeltaEELV) and, therefore, dynamic hyperinflation. The combination of static and dynamic hyperinflation was reflected by inspiratory reserve volume (IRV) during the activity. RESULTS: Overall, increase in EELV occurred in GOLD II-IV without significant difference between the groups. There was a tendency for a smaller DeltaEELV in GOLD IV. DeltaEELV was inversely related to static hyperinflation. IRV during the daily activity was related to the level of airflow obstruction. CONCLUSIONS: Dynamic hyperinflation occurs independent of GOLD stage during real-life daily activities. The combination of static and dynamic hyperinflation, however, increases with increasing airflow obstruction.

Performance during constant workrate cycling exercise in women with COPD and hyperinflation.

We aimed to characterize gender differences in exercise endurance, operating lung volumes and symptoms limitation during exercise in patients with COPD. Ninety-three women and 93 men with COPD matched for age and disease severity were evaluated during symptom-limited constant-work rate cycle exercise at 75% of peak capacity. Breathing pattern, inspiratory capacity, dyspnoea and leg discomfort Borg scores were recorded during exercise. Endurance time was shorter in women compared to men. Inspiratory capacity decreased at a similar rate during exercise in women and men (0.71 vs. 0.81 ml x s(- 1) for women and men respectively, p = 0.47) despite lower ventilation at end-exercise in women. At end-exercise, women showed lower inspiratory reserve volume (p < 0.005). Dyspnoea responses during exercise occurred with a steep rise near end-exercise, when inspiratory reserve volume approached a critical value, at 10% of total lung capacity, this onset of dyspnoea acceleration occurred earlier in women (p < 0.0001). At the same relative exercise intensity, women with COPD had lower endurance time than men. Compared to men, women with COPD were disadvantaged during exercise as they reached a critical inspiratory reserve volume earlier, leading to a steep increase in dyspnoea and to exercise termination.