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.

The asthma-obesity relationship: underlying mechanisms and treatment implications.

PURPOSE OF REVIEW: Obesity is a worldwide epidemic with a prevalence that has tripled in the last two decades. Worldwide, more than 1.5 billion adults are overweight and more than 500 million obese. Obesity has been suggested to be a risk factor for the development of more difficult-to-control asthma. Although the mechanisms underlying the asthma-obesity relationship are not fully understood, several possible explanations have been put forward. These will be reviewed in this manuscript as well as the implications for the treatment of overweight and obese asthma patients. RECENT FINDINGS: Insulin resistance is a possible factor contributing to the asthma-obesity relationship and the effect is independent of other components of the metabolic syndrome such as hypertriglyceridemia, hypertension, hyperglycemia, and systemic inflammation. Obesity has important effects on airway geometry, by especially reducing expiratory reserve volume causing obese asthmatics to breathe at low lung volumes. Furthermore, obesity affects the type of inflammation in asthma and is associated with reduced inhaled corticosteroids treatment responsiveness. SUMMARY: Obesity induces the development of asthma with a difficult-to-control phenotype. Treatment targeting insulin resistance may be beneficial in obese asthma patients, especially when they have concomitant diabetes. Systemic corticosteroids should be avoided as much as possible as they are not very effective in obese asthma and associated with side-effects like diabetes, weight gain, and osteoporosis.

Cardiovascular and respiratory effects of the neoprene wetsuit in non-immersed divers.

A neoprene wetsuit is widely used to reduce thermal dispersion during diving. Recent observations have pointed out that elastic recoil of the wetsuit might have significant compressive effects, able to affect water and electrolyte homeostasis during both dry and immersed conditions. The aim of this study was to evaluate the possible cardiovascular and respiratory effects of the neoprene wetsuit in dry conditions in a sample of experienced divers. Twenty-four (24) healthy divers were evaluated by Doppler-echocardiography and by spirometry in basal conditions and while wearing a full neoprene wetsuit. During wetsuit conditions, we observed a significant decrease in heart rate (-5%; p ⟨ 0.05) and cardiac output (-12%; p ⟨ 0.05), and a significant increase in total peripheral resistances (15%; p ⟨ 0.05). Moreover, a significant reduction of right ventricular early diastolic filling was observed (-15%; p ⟨ 0.05). As concerns pulmonary function, a significant reduction of vital capacity (-2%; p ⟨ 0.001) and expiratory reserve volume (-25%; p ⟨ 0.001), and a significant increase of inspiratory capacity (9%; p ⟨ 0.001) and tidal volume (25%; p ⟨ 0.05) were observed. These data support the hypothesis that neoprene elastic recoil, possibly due to a compression exerted on chest, might affect systemic circulation (decreasing cardiac output and impairing right ventricular filling) and respiratory function.

The effects of obesity on lung volumes and oxygenation.

INTRODUCTION: Obesity can cause hypoxemia by decreasing lung volumes to where there is closure of lung units during normal breathing. Studies describing this phenomenon are difficult to translate into clinical practice. We wanted to determine the lung volume measurements that are associated with hypoxemia in obese patients, and explore how we could use these measurements to identify them. METHODS: We collected pulmonary function test results and arterial blood gas data on 118 patients without obstruction on pulmonary function testing. We included only patients with normal chest imaging and cardiac testing within one year of the pulmonary function test, to exclude other causes of hypoxemia. RESULTS: We found that as BMI increases, the mean paO2, ERV % predicted, and ERV/TLC decrease (BMI 20-30 kg/m2: paO2=90±8 mmHg, ERV% predicted 112±50, ERV/TLC (%) 19.7±6.5; BMI 30-40 kg/m2: paO2=84±10 mmHg, ERV% predicted 84±40 ERV/TLC(%) 13.6±7.6; BMI>40 kg/m2: paO2 78 ±12 mmHg, ERV% predicted 64±27 ERV/TLC(%) 11.4±5.8, ANOVA p<0.001). The A-a gradient increases as BMI increases (r=0.42, p<0.001). This correlation was stronger in men (r=0.54) than in women (r=0.35). The paO2 is lower in patients with a low ERV than in those with a normal ERV (p<0.001). In a multivariate linear regression, only the ERV/TLC predicted (%), age, and BMI were associated with oxygenation (r2 for A-a gradient =0.28, p=0.036). CONCLUSIONS: In obese patients without cardiopulmonary disease, oxygen levels decrease as BMI increases. This effect is associated with the obesity-related reduction in ERV and is independent of hypoventilation.

Overweight Is an Independent Risk Factor for Reduced Lung Volumes in Myotonic Dystrophy Type 1.

BACKGROUND: In this large observational study population of 105 myotonic dystrophy type 1 (DM1) patients, we investigate whether bodyweight is a contributor of total lung capacity (TLC) independent of the impaired inspiratory muscle strength. METHODS: Body composition was assessed using the combination of body mass index (BMI) and fat-free mass index. Pulmonary function tests and respiratory muscle strength measurements were performed on the same day. Patients were stratified into normal (BMI < 25 kg/m(2)) and overweight (BMI ≥ 25 kg/m(2)) groups. Multiple linear regression was used to find significant contributors for TLC. RESULTS: Overweight was present in 59% of patients, and body composition was abnormal in almost all patients. In overweight patients, TLC was significantly (p = 2.40×10(-3)) decreased, compared with normal-weight patients, while inspiratory muscle strength was similar in both groups. The decrease in TLC in overweight patients was mainly due to a decrease in expiratory reserve volume (ERV) further illustrated by a highly significant (p = 1.33×10(-10)) correlation between BMI and ERV. Multiple linear regression showed that TLC can be predicted using only BMI and the forced inspiratory volume in 1 second, as these were the only significant contributors. CONCLUSIONS: This study shows that, in DM1 patients, overweight further reduces lung volumes, as does impaired inspiratory muscle strength. Additionally, body composition is abnormal in almost all DM1 patients.

What can impulse oscillometry and pulmonary function testing tell us about obstructive sleep apnea: a case-control observational study?

PURPOSE: This study aims to determine whether functional residual capacity (FRC) in obese patients with obstructive sleep apnea (OSA) decreases more than in patients without OSA because of decreased outward recoil from chest wall mass loading as well as increased lung inward recoil. METHODS: Subjects who were overweight and obese to various degrees with normal spirometric values underwent overnight polysomnography to determine the presence or absence of OSA and were labeled as cases or controls. Lung volume and respiratory mechanical properties were measured by plethysmograph and impulse oscillometry, respectively. RESULTS: A total of 76 men and 31 women were diagnosed with OSA (cases); 64 men and 33 women without OSA were confirmed as controls. Expiratory reserve volume and FRC were significantly decreased in cases compared with controls. Respiratory impedance and resistance at 5 Hz were significantly higher in cases than in controls, although reactance at low frequencies was significantly lower in cases than in controls. Reactance at 5 Hz (Xrs5) was found to be independently highly correlated with the severity of OSA as defined by the Apnea-Hypopnea Index and was significantly correlated with FRC. CONCLUSIONS: FRC is significantly decreased in overweight or obese patients with OSA compared with those without OSA, which may be attributed to an increase in lung elastic recoil. The stronger correlation between Xrs5 and OSA severity might indicate upper airway stenosis, and abnormally increased lung elastic recoil may contribute to OSA.

OPTIMUM LEVEL OF POSITIVE END-EXPIRATORY PRESSURE IN ACUTE RESPIRATORY DISTRESS SYNDROME CAUSED BY INFLUENZA A(H1NI)PDM09: BALANCE BETWEEN MAXIMAL END-EXPIRATORY VOLUME AND MINIMAL ALVEOLAR OVERDISTENSION.

THE AIM: to determine optimum level ofpositive end-expiratory pressure (PEEP) according to balance between maxi- mal end-expiratory lung volume (EEL V)(more than predicted) and minimal decrease in exhaled carbon dioxide volume (VCO) and then to develop the algorithm of gas exchange correction based on prognostic values of EEL K; alveolar recruitability, PA/FiO2, static compliance (C,,,) and VCO2. MATERIALS AND METHODS: 27 mechanically ventilatedpatients with acute respiratory distress syndrome (ARDS) caused by influenza A (HINJ)pdm09 in Moscow Municipal Clinics ICU's from January to March 2016 were included in the trial. At the beginning of the study patients had the following characteristic: duration offlu symptoms 5 (3-10) days, p.0/FiO2 120 (70-50) mmHg. SOFA 7 (5-9), body mass index 30.1 (26.4-33.8) kg/m², static compliance of respiratory system 35 (30-40) ml/mbar: Under sedation and paralysis we measured EELV, C VCO and end-tidal carbon dioxide concentration (EtCO) (for CO2 measurements we fixed short-term values after 2 min after PEEP level change) at PEEP 8, 11,13,15,18, 20 mbar consequently, and incase of good recruitability, at 22 and 24 mbar. After analyses of obtained data we determined PEEP value in which increase in EELV was maximal (more than predicted) and depression of VCO2 was less than 20%, change in mean blood pressure and heart rate were both less than 20% (measured at PEEP 8 mbar). After that we set thus determined level of PEEP and didn't change it for 5 days. RESULTS: Comparision of predicted and measured EELV revealed two typical points of alveloar recruiment: the first at PEEP 11-15 mbar, the second at PEEP 20-22 mbar. EELV measured at PEEP 18 mbar appeared to be higher than predicted at PEEP 8 mbar by 400 ml (approx.), which was the sign of alveolar recruitment-1536 (1020-1845) ml vs 1955 (1360-2320) ml, p=0,001, Friedman test). we didn't found significant changes of VCO2 when increased PEEP in the range from 8 to 15 mbar (p>0.05, Friedman test). PEEP increase from 15 to 18 mbar and more lead to decrease in VCO2 (from 212 (171-256) ml/min to 200 (153-227) ml/min, p<0,0001, Friedman test, which was the sign of overdistension. Next decrease of VCO2 was observed at PEEP increase from 22 to 24 mbar (from 203 (174-251 ml/min) to 185 (182-257) ml/min, p=0.0025, Friedman test). Adjusted PEEP value according to balance between recruitment and overdistension was higher than the one initially set (16(15-18) mbar vs 12(7-15) mbar, p <0.0001). We observed increase of SpO2 from 93 (87-96) to 97(95-100)% (p<0.0001 followed by decrease in inspiratory oxygen fraction from 60(40-80) to 50(40-60)%(p<0.0001). Low EELV VCO2 and VCO2/EtCO2 at PEEP 8 mbar has low predictive value for death (AUROC 0,547, 0706 and 0.596, respectively).Absolute EELV value at PEEP 18 and 20 mbar were poor predictors of mortality (AUROC 0.61 and 0.65 respectively) Alveolar recruit ability was measured by subtraction of EELV at PEEP 20 and at PEEP II mbar - value below 575 ml was a good predictor of death (sensitivity 75%, specificity 88%, AUROC 0.81). Lowering of VCO2 at PEEP 20 mbar to less than 207 ml/min was a marker of alveolar overdistension and associated with poor prognosis (sensitivity 83%, specificity 88%, AUROC 0,89). C has poor predictive value at PEEP 8 and 20 mbar (AUROC 0,58 and 0,74 respectively. Conclusion: PEEP adjustment in ARDS due to influenza A (H1N1) pdm09 in accordance with balance between recruitment and overdistension (based on EELV and VCO measurements) can improve gas exchange, probably, not leading to right ventricular failure. This value of "balanced" PEEP is in the range between 15 and 18 mbar: Low lung recruitabiilty is associated with poor prognosis. Measurements of EELV and VCO2 at PEEP 8 and 20 mbar can be used to make a decision on whether to keep "high" PEEP level or switch to extracorporeal membrane oxygenation in patient with ARDS due to influenza A (N1H1).

Obesity and Pulmonary Function in African Americans.

BACKGROUND: Obesity prevalence in United States (US) adults exceeds 30% with highest prevalence being among blacks. Obesity is known to have significant effects on respiratory function and obese patients commonly report respiratory complaints requiring pulmonary function tests (PFTs). However, there is no large study showing the relationship between body mass index (BMI) and PFTs in healthy African Americans (AA). OBJECTIVE: To determine the effect of BMI on PFTs in AA patients who did not have evidence of underlying diseases of the respiratory system. METHODS: We reviewed PFTs of 339 individuals sent for lung function testing who had normal spirometry and lung diffusion capacity for carbon monoxide (DLCO) with wide range of BMI. RESULTS: Functional residual capacity (FRC) and expiratory reserve volume (ERV) decreased exponentially with increasing BMI, such that morbid obesity resulted in patients breathing near their residual volume (RV). However, the effects on the extremes of lung volumes, at total lung capacity (TLC) and residual volume (RV) were modest. There was a significant linear inverse relationship between BMI and DLCO, but the group means values remained within the normal ranges even for morbidly obese patients. CONCLUSIONS: We showed that BMI has significant effects on lung function in AA adults and the greatest effects were on FRC and ERV, which occurred at BMI values < 30 kg/m2. These physiological effects of weight gain should be considered when interpreting PFTs and their effects on respiratory symptoms even in the absence of disease and may also exaggerate existing lung diseases.

Dysanapsis and the resistive work of breathing during exercise in healthy men and women.

We asked if the higher work of breathing (Wb) during exercise in women compared with men is explained by biological sex. We created a statistical model that accounts for both the viscoelastic and the resistive components of the total Wb and independently compares the effects of biological sex. We applied the model to esophageal pressure-derived Wb values obtained during an incremental cycle test to exhaustion. Subjects were healthy men (n = 17) and women (n = 18) with a range of maximal aerobic capacities (V̇o2 max range: men = 40-68 and women = 39-60 ml·kg(-1)·min(-1)). We also calculated the dysanapsis ratio using measures of lung recoil and forced expiratory flow as index of airway caliber. By applying the model we found that the differences in the total Wb during exercise in women are due to a higher resistive Wb rather than viscoelastic Wb. We also found that the higher resistive Wb is independently explained by biological sex. To account for the known effect of lung volumes on the dysanapsis ratio we compared the sexes with an analysis of covariance procedures and found that when vital capacity was accounted for the adjusted mean dysanapsis ratio is statistically lower in women (0.17 vs. 0.25 arbitrary units; P < 0.05). Our collective findings suggest that innate sex-based differences may exist in human airways, which result in significant male-female differences in the Wb during exercise in healthy subjects.

Endurance exercise performance in acute hypoxia is influenced by expiratory flow limitation.

PURPOSE: We sought to determine if expiratory flow limitation influences intensive aerobic exercise performance in mild hypoxia. METHODS: Fourteen trained male cyclists were separated into flow-limited (FL, n = 7) and non-FL (n = 7) groups based on the extent of expiratory flow limitation exhibited during maximal exercise in normoxia. Participants performed two self-paced 5-km cycling time trials, one in normoxic (F IO2 = 0.21) and one in mild hypoxic (F IO2 = 0.17) conditions in a randomized, balanced order with the subjects blinded to composition of the inspirate. Percent change from normoxia to hypoxia in average power output (%ΔP TT) and time to completion (%ΔT TT) were used to assess performance. RESULTS: Hypoxia resulted in a significant decline in estimated arterial O2 saturation and decrements in performance in both groups, although FL had a significantly smaller %ΔP TT (-4.0 ± 0.5 vs. -9.0 ± 1.8 %) and %ΔT TT (1.3 ± 0.3 vs. 3.7 ± 0.9 %) compared to non-FL. At the 5th km of the time trial, minute ventilation did not change from normoxia to hypoxia in FL (3.4 ± 3.1 %) or non-FL (2.3 ± 3.7 %), but only the non-FL reported a significantly increased dyspnea rating in hypoxia compared to normoxia (~9 %). Non-FL athletes did not utilize their ventilatory reserve to defend arterial oxygen saturation in hypoxia, which may have been due to an increased measure of dyspnea in the hypoxic trial. CONCLUSION: FL athletes experience less hypoxia-related aerobic exercise performance impairment as compared to non-FL athletes, despite having less ventilatory reserve.

Expiratory Reserve Volume During Slow Expiration With Glottis Opened in Infralateral Decubitus Position (ELTGOL) in Chronic Pulmonary Disease: Technique Description and Reproducibility.

BACKGROUND: There has not been a detailed description of expiratory reserve volume (ERV) during slow expiration with glottis open in infralateral decubitus position (ELTGOL, for Expiration Lente Totale Glotte Ouverte en infraLatéral) and its reproducibility. The aim of this study was to determine ERV during ELTGOL and to evaluate ERV intra-observer and inter-observer reliability. METHODS: In this prospective study, subjects were 30-70 y of age with chronic lung disease. ELTGOL (an active-passive or active physiotherapy technique) was applied in random order by 3 observers: 2 trained physiotherapists (PT 1 and PT 2) and the subject him/herself. Two ELTGOL compressions (A and B) were applied by PT 1, PT 2, and the subject. RESULTS: Thirty-two subjects were evaluated with moderate lung obstruction, FEV1: 47.7 ± 15.4, and ERV: 61.7 ± 29.4. The mean value of ERV for PT 1 was 51.4 ± 24.8%; for PT 2, it was 54.3 ± 31.8%; and for the subject, it was 53.5 ± 26.2% (P = .49). Considering the mean value of ERV, the ELTGOL mobilized more than 80% of ERV. There was good reliability intra-PT: PT 1, intraclass correlation coefficient (ICC) 0.85 (0.70-0.93), P < .0001; PT 2, ICC 0.90 (0.80-0.95), P < .0001, and inter-PT (ICC 0.86 [95% CI 0.71-0.93], P < .001). The Bland-Altman plot with mean bias and limits of agreement for ERV of PT 1 and PT 2 was -3.3 (-42.7 to 35.9). CONCLUSIONS: ELTGOL mobilized more than 80% of ERV in subjects with moderate airway obstruction; there is no difference in ERV exhaled during the technique applied by a physiotherapist or by the subject. ELTGOL is a reproducible technique, determined by inter- and intra-observer testing.

Lung recruitment and endotracheal suction in ventilated preterm infants measured with electrical impedance tomography.

AIMS: Although suctioning is a standard airway maintenance procedure, there are significant associated risks, such as loss of lung volume due to high negative suction pressures. This study aims to assess the extent and duration of change in end-expiratory level (EEL) resulting from endotracheal tube (ETT) suction and to examine the relationship between EEL and regional lung ventilation in ventilated preterm infants with respiratory distress syndrome. METHODS: A prospective observational clinical study of the effect of ETT suction on 20 non-muscle-relaxed preterm infants with respiratory distress syndrome (RDS) on conventional mechanical ventilation was conducted in a neonatal intensive care unit. Ventilation distribution was measured with regional impedance amplitudes and EEL using electrical impedance tomography. RESULTS: ETT suction resulted in a significant increase in EEL post-suction (P < 0.01). Regionally, anterior EEL decreased and posterior EEL increased post-suction, suggesting heterogeneity. Tidal volume was significantly lower in volume-guarantee ventilation compared with pressure-controlled ventilation (P = 0.04). CONCLUSIONS: ETT suction in non-muscle-relaxed and ventilated preterm infants with RDS results in significant lung volume increase that is maintained for at least 90 min. Regional differences in distribution of ventilation with ETT suction suggest that the behaviour of the lung is heterogeneous in nature.

Obesity and asthma.

There is a global epidemic of asthma and obesity that is concentrated in Westernized and developed countries. A causal association in some people with asthma is suggested by observations that obesity precedes the onset of asthma and that bariatric surgery for morbid obesity can resolve asthma. The obese asthma phenotype features poor asthma control, limited response to corticosteroids, and an exaggeration of the physiological effects of obesity on lung function, which includes a reduction in expiratory reserve volume and airway closure occurring during tidal breathing. Obesity has important implications for asthma treatment. Increasing corticosteroid doses based on poor asthma control, as currently recommended in guidelines, may lead to overtreatment with corticosteroids in obese asthma. Enhanced bronchodilation, particularly of the small airways, may reduce the component of airway closure due to increased bronchomotor tone and suggests that greater emphasis should be placed on long-acting bronchodilators in obese asthma. The societal implications of this are important: with increasing obesity there will be increasing asthma from obesity, and the need to identify successful individual and societal weight-control strategies becomes a key goal.

Evaluation of fractional regional ventilation using 4D-CT and effects of breathing maneuvers on ventilation.

PURPOSE: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. METHODS AND MATERIALS: Eight patients underwent 3 sets of 4D-CT scans during 1 session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. RESULTS: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R2 of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the "mass corrected" FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. CONCLUSIONS: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic resonance imaging. These results were demonstrated on retrospective analysis of patient data, and further research using prospective data is under way to validate this technique against established clinical tests.

Impact of the prolonged slow expiratory maneuver on respiratory mechanics in wheezing infants.

OBJECTIVE: To evaluate changes in respiratory mechanics and tidal volume (V T) in wheezing infants in spontaneous ventilation after performing the technique known as the prolonged, slow expiratory (PSE) maneuver. METHODS: We included infants with a history of recurrent wheezing and who had had no exacerbations in the previous 15 days. For the assessment of the pulmonary function, the infants were sedated and placed in the supine position, and a face mask was used and connected to a pneumotachograph. The variables of tidal breathing (V T and RR) as well as those of respiratory mechanics-respiratory system compliance (Crs), respiratory system resistance (Rrs), and the respiratory system time constant (prs)-were measured before and after three consecutive PSE maneuvers. RESULTS: We evaluated 18 infants. The mean age was 32 ± 11 weeks. After PSE, there was a significant increase in V T (79.3 ± 15.6 mL vs. 85.7 ± 17.2 mL; p = 0.009) and a significant decrease in RR (40.6 ± 6.9 breaths/min vs. 38.8 ± 0,9 breaths/min; p = 0.042). However, no significant differences were found in the variables of respiratory mechanics (Crs: 11.0 ± 3.1 mL/cmH2O vs. 11.3 ± 2.7 mL/cmH2O; Rrs: 29.9 ± 6.2 cmH2O • mL-1 • s-1 vs. 30.8 ± 7.1 cmH2O • mL-1 • s-1; and prs: 0.32 ± 0.11 s vs. 0.34 ±0.12 s; p > 0.05 for all). CONCLUSIONS: This respiratory therapy technique is able to induce significant changes in V T and RR in infants with recurrent wheezing, even in the absence of exacerbations. The fact that the variables related to respiratory mechanics remained unchanged indicates that the technique is safe to apply in this group of patients. Studies involving symptomatic infants are needed in order to quantify the functional effects of the technique.

Impacto da técnica de expiração lenta e prolongada na mecânica respiratória de lactentes sibilantes / Impact of the prolonged slow expiratory maneuver on respiratory mechanics in wheezing infants

OBJETIVO: Avaliar as alterações da mecânica respiratória e do volume corrente (VC) em lactentes sibilantes em ventilação espontânea após a realização da técnica de expiração lenta e prolongada (ELPr). MÉTODOS: Foram incluídos no estudo lactentes com história de sibilância recorrente e sem exacerbações nos 15 dias anteriores. Para a avaliação da função pulmonar, os lactentes foram sedados e posicionados em decúbito dorsal com máscara facial acoplada a um pneumotacógrafo. As variáveis da respiração corrente - VC e FR - e da mecânica respiratória - complacência do sistema respiratório (Csr), resistência (Rsr) e constante de tempo (psr) - foram mensuradas antes e após a realização de três sequências consecutivas de ELPr. RESULTADOS: Foram avaliados 18 lactentes, com média de idade de 32 ± 11 semanas. Houve um aumento significante no VC após ELPr (79,3 ± 15,6 mL vs. 85,7 ± 17,2 mL; p = 0,009), assim como uma redução na FR (40,6 ± 6,9 ciclos/min vs. 38,8 ± 0,9 ciclos/min; p = 0,042). Entretanto, não houve alterações significantes nos valores da mecânica respiratória (Csr: 11,0 ± 3,1 mL/cmH2O vs. 11,3 ± 2,7 mL/cmH2O; Rsr: 29,9 ± 6,2 cmH2O • mL-1 • s-1 vs. 30,8 ± 7,1 cmH2O • mL-1 • s-1; e psr: 0,32 ± 0,11 s vs. 0,34 ± 0,12 s; p > 0,05 para todos). CONCLUSÕES: Essa técnica de fisioterapia respiratória é capaz de induzir alterações significativas no VC e na FR de lactentes com sibilância recorrente, mesmo na ausência de exacerbações. A manutenção das variáveis da mecânica respiratória indica que a técnica é segura para ser aplicada nesse grupo de pacientes. Estudos com lactentes sintomáticos são necessários para quantificar os efeitos funcionais da técnica.

OBJECTIVE: To evaluate changes in respiratory mechanics and tidal volume (V T) in wheezing infants in spontaneous ventilation after performing the technique known as the prolonged, slow expiratory (PSE) maneuver. METHODS: We included infants with a history of recurrent wheezing and who had had no exacerbations in the previous 15 days. For the assessment of the pulmonary function, the infants were sedated and placed in the supine position, and a face mask was used and connected to a pneumotachograph. The variables of tidal breathing (V T and RR) as well as those of respiratory mechanics-respiratory system compliance (Crs), respiratory system resistance (Rrs), and the respiratory system time constant (prs)-were measured before and after three consecutive PSE maneuvers. RESULTS: We evaluated 18 infants. The mean age was 32 ± 11 weeks. After PSE, there was a significant increase in V T (79.3 ± 15.6 mL vs. 85.7 ± 17.2 mL; p = 0.009) and a significant decrease in RR (40.6 ± 6.9 breaths/min vs. 38.8 ± 0,9 breaths/min; p = 0.042). However, no significant differences were found in the variables of respiratory mechanics (Crs: 11.0 ± 3.1 mL/cmH2O vs. 11.3 ± 2.7 mL/cmH2O; Rrs: 29.9 ± 6.2 cmH2O • mL-1 • s-1 vs. 30.8 ± 7.1 cmH2O • mL-1 • s-1; and prs: 0.32 ± 0.11 s vs. 0.34 ±0.12 s; p > 0.05 for all). CONCLUSIONS: This respiratory therapy technique is able to induce significant changes in V T and RR in infants with recurrent wheezing, even in the absence of exacerbations. The fact that the variables related to respiratory mechanics remained unchanged indicates that the technique is safe to apply in this group of patients. Studies involving symptomatic infants are needed in order to quantify the functional effects of the technique.

Assessment of a pharmacist-driven point-of-care spirometry clinic within a primary care physicians office / Evaluación de una clínica de espirometría dirigida por un farmacéutico en la consulta de un médico general

Objective: To assess value-added service of a pharmacist-driven point-of-care spirometry clinic to quantify respiratory disease abnormalities within a primary care physicians office Methods: This retrospective, cohort study was an analysis of physician referred patients who attended our spirometry clinic during 2008-2010 due to pulmonary symptoms or disease. After spirometry testing, data was collected retrospectively to include patient demographics, spirometry results, and pulmonary pharmaceutical interventions. Abnormal spirometry was identified as an obstructive and/or restrictive defect. Results: Sixty-five patients with a primary diagnosis of cough, shortness of breath, or diagnosis of asthma or chronic obstructive pulmonary disease were referred to the spirometry clinic for evaluation. A total of 51 (32 patients with normal spirometry, 19 abnormal spirometry) completed their scheduled appointment. Calculated lung age was lower in normal spirometry (58.1; SD=20 yrs) than abnormal spirometry (78.2; SD=7.5 yrs, p<0.001). Smoking pack years was also lower in normal spirometry (14.4; SD=10.7 yrs) than abnormal spirometry (32.7; SD=19.5 yrs, p=0.004). Resting oxygen saturation of the arterial blood (SaO2) was higher in normal spirometry than abnormal spirometry (98.1% vs 96.5%, p=0.016). Mean change in the forced expiratory volume in one second (FEV1) after administration of bronchodilator was greater in patients with abnormal spirometry compared with normal spirometry (10.9% vs 4.1%, p<0.001). Spirometry testing assisted in addition, discontinuation or altering pulmonary drug regimens in 41/51 patients (80%) and the need for further diagnostic testing or physician referral in 14/51 patients (27.4%). Conclusion: Implementation of a pharmacist-driven spirometry clinic is a value-added service that can be integrated with other clinical pharmacy services within the ambulatory care setting. Further studies are needed to determine the role of pharmacists in performing spirometry testing and measuring performance outcomes of the pulmonary patient (AU)

Objetivo: Evaluar el valor añadido de un servicio dirigido por un farmacéutico de una clínica rápida de espirometría para cuantificar las anomalías respiratorias en una consulta de un médico general. Métodos: Este estudio de cohorte prospectiva fue un análisis de los pacientes referidos por un médico que visitaron nuestra clínica de espirometría durante 2008-2010 debido a síntomas o enfermedad pulmonar. Después de la espirometría, se recogieron retrospectivamente los datos demográficos de los pacientes, los resultados de la espirometría y las intervenciones farmacéuticas. Se identificó una espirometría anormal cuando había una obstrucción o un defecto restrictivo. Resultados: 65 pacientes con diagnostico primario de tos, dificultad de respiratoria, o diagnóstico de asma o enfermedad pulmonar obstructiva crónica fueron referidos a la clínica de espirometría para evaluación. Un total de 51 pacientes (32 con espirometría normal y 19 con anomalías espirométricas) completó el esquema de citas. La edad pulmonar calculada fue menor en las espirometrías normales (58,1; DE=20 años) que en las anormales (78,2; DE=7,5 años; p<0,001). Los años de fumador fueron también menores en las espirometrías normales (14,4; DE=10,7 años) que en las anormales (32,7; DE=19,5 años; p=0,004). La saturación en reposo de oxígeno en la sangre arterial (SaO2) era superior en las espirometrías normales que en las anormales (98,1% vs. 96,5%, p=0,016). El cabio medio en el volumen espiratorio forzado en un segundo (FEV1) después de la administración de un broncodilatador fue mayor en pacientes con espirometría anormal comparado con las normales (10,9% vs. 4,1%; p<0,001). La espirometría ayudó en la adición, discontinuación o alteración de los tratamientos pulmonares en 41/51 pacientes (80%) y en la necesidad de pruebas posteriores o derivación al médico en 14/51 pacientes (24,4%). Conclusión: La implantación de una clínica espirométrica dirigida por un farmacéutico es un servicio de valor añadido que puede integrarse con otros servicios de farmacia clínica en los ambulatorios. Se necesitan más estudios para determinar el papel del farmacéutico realizando espirometrías y midiendo el funcionamiento de los resultados en salud de los pacientes pulmonaes (AU)

Generalized anxiety disorder is associated with reduced lung function in the Vietnam Experience Study.

BACKGROUND: There is no clear consensus in the few studies to have explored the relationship between major mental health disorders and lung function. The present study examined the cross-sectional associations of generalized anxiety disorder (GAD) and major depressive disorder (MDD) with lung function in a large study of male US veterans. METHODS: Participants (N = 4256) were drawn from the Vietnam Experience Study. From military files, telephone interviews, and a medical examination, anthropometric, sociodemographic, and health data were collected. One-year prevalence of GAD and MDD was determined using DSM-III criteria. Forced expiratory volume in 1 second was measured by spirometry. RESULTS: In models that adjusted for age and height, both GAD (p < .001) and MDD (p = .004) were associated with lower forced expiratory volume in 1 second. In models additionally adjusting for weight, place of service, ethnicity, marriage, smoking, alcohol consumption, income, education, and major illness, GAD was still associated with poorer lung function (p = .01), whereas MDD was not (p = .18). CONCLUSIONS: Depression has very much been the focus of studies on mental health and physical health status. The current findings suggest that future research should perhaps pay equal attention to GAD.

End-expiratory lung volume and ventilation distribution with different continuous positive airway pressure systems in volunteers.

BACKGROUND: Continuous positive airway pressure (CPAP) has been shown to improve oxygenation and a number of different CPAP systems are available. The aim of this study was to assess lung volume and ventilation distribution using three different CPAP techniques. METHODS: A high-flow CPAP system (HF-CPAP), an ejector-driven system (E-CPAP) and CPAP using a Servo 300 ventilator (V-CPAP) were randomly applied at 0, 5 and 10 cmH2O in 14 volunteers. End-expiratory lung volume (EELV) was measured by N2 dilution at baseline; changes in EELV and tidal volume distribution were assessed by electric impedance tomography. RESULTS: Higher end-expiratory and mean airway pressures were found using the E-CPAP vs. the HF-CPAP and the V-CPAP system (P<0.01). EELV increased markedly from baseline, 0 cmH2O, with increased CPAP levels: 1110±380, 1620±520 and 1130±350 ml for HF-, E- and V-CPAP, respectively, at 10 cmH2O. A larger fraction of the increase in EELV occurred for all systems in ventral compared with dorsal regions (P<0.01). In contrast, tidal ventilation was increasingly directed toward dorsal regions with increasing CPAP levels (P<0.01). The increase in EELV as well as the tidal volume redistribution were more pronounced with the E-CPAP system as compared with both the HF-CPAP and the V-CPAP systems (P<0.05) at 10 cmH2O. CONCLUSION: EELV increased more in ventral regions with increasing CPAP levels, independent of systems, leading to a redistribution of tidal ventilation toward dorsal regions. Different CPAP systems resulted in different airway pressure profiles, which may result in different lung volume expansion and tidal volume distribution.