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1.
Undersea Hyperb Med ; 48(2): 107-117, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33975401

RESUMO

Introduction: Pre-dive altitude exposure may increase respiratory fatigue and subsequently augment exercise ventilation at depth. This study examined pre-dive altitude exposure and the efficacy of resistance respiratory muscle training (RMT) on respiratory fatigue while diving at altitude. Methods: Ten men (26±5 years; VO2peak: 39.8±3.3 mL• kg-1•min-1) performed three dives; one control (ground level) and two simulated altitude dives (3,658 m) to 17 msw, relative to ground level, before and after four weeks of resistance RMT. Subjects performed pulmonary function testing (e.g., inspiratory [PI] and expiratory [PE] pressure testing) pre- and post-RMT and during dive visits. During each dive, subjects exercised for 18 minutes at 55% VO2peak, and ventilation (VE), breathing frequency (ƒb,), tidal volume (VT) and rating of perceived exertion (RPE) were measured. Results: Pre-dive altitude exposure reduced PI before diving (p=0.03), but had no effect on exercise VE, ƒb, or VT at depth. At the end of the dive in the pre-RMT condition, RPE was lower (p=0.01) compared to control. RMT increased PI and PE (p<0.01). PE was reduced from baseline after diving at altitude (p<0.03) and this was abated after RMT. RMT did not improve VE or VT at depth, but decreased ƒb (p=0.01) and RPE (p=0.048) during the final minutes of exercise. Conclusion: Acute altitude exposure pre- and post-dive induces decrements in PI and PE before and after diving, but does not seem to influence ventilation at depth. RMT reduced ƒb and RPE during exercise at depth, and may be useful to reduce work of breathing and respiratory fatigue during dives at altitude.


Assuntos
Altitude , Exercícios Respiratórios/métodos , Mergulho/fisiologia , Exercício Físico/fisiologia , Fadiga Muscular/fisiologia , Trabalho Respiratório/fisiologia , Adulto , Análise de Variância , Exposição Ambiental , Expiração/fisiologia , Frequência Cardíaca , Humanos , Inalação/fisiologia , Masculino , Oxigênio/sangue , Consumo de Oxigênio/fisiologia , Esforço Físico/fisiologia , Treinamento de Força/métodos , Testes de Função Respiratória , Volume de Ventilação Pulmonar/fisiologia , Fatores de Tempo
2.
Anesthesiology ; 134(4): 518-525, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33404638

RESUMO

Clinicians who care for patients infected with coronavirus disease 2019 (COVID-19) must wear a full suite of personal protective equipment, including an N95 mask or powered air purifying respirator, eye protection, a fluid-impermeable gown, and gloves. This combination of personal protective equipment may cause increased work of breathing, reduced field of vision, muffled speech, difficulty hearing, and heat stress. These effects are not caused by individual weakness; they are normal and expected reactions that any person will have when exposed to an unusual environment. The physiologic and psychologic challenges imposed by personal protective equipment may have multiple causes, but immediate countermeasures and long-term mitigation strategies can help to improve a clinician's ability to provide care. Ultimately, a systematic approach to the design and integration of personal protective equipment is needed to improve the safety of patients and clinicians.


Assuntos
COVID-19/prevenção & controle , Pessoal de Saúde/estatística & dados numéricos , Equipamento de Proteção Individual/efeitos adversos , Desempenho Profissional/estatística & dados numéricos , Desenho de Equipamento , Audição , Resposta ao Choque Térmico , Humanos , SARS-CoV-2 , Fala , Campos Visuais , Trabalho Respiratório
3.
Am J Physiol Regul Integr Comp Physiol ; 320(3): R268-R275, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33356877

RESUMO

The modified Campbell diagram provides one of the most comprehensive assessments of the work of breathing (Wb) during exercise, wherein the resistive and elastic work of inspiration and expiration are quantified. Importantly, a necessary step in constructing the modified Campbell diagram is to obtain a value for chest wall compliance (CCW). To date, it remains unknown whether estimating or directly measuring CCW impacts the Wb, as determined by the modified Campbell diagram. Therefore, the purpose of this study was to evaluate whether the components of the Wb differ when the modified Campbell diagram is constructed using an estimated versus measured value of CCW. Forty-two participants (n = 26 men, 16 women) performed graded exercise to volitional exhaustion on a cycle ergometer. CCW was measured directly at rest via quasistatic relaxation. Estimated values of CCW were taken from prior literature. The measured value of CCW was greater than that obtained via estimation (214 ± 52 mL/cmH2O vs. 189 ± 18 mL/cmH2O; P < 0.05). At modest-to-high minute ventilations (i.e., 50-200 L/min), the inspiratory elastic Wb was greater and expiratory resistive Wb was lower, when modified Campbell diagrams were constructed using estimated compared with measured values of CCW (P = 0.001). These differences were however small and never exceeded ±5%. Thus, although our findings demonstrate that estimating CCW has a measurable impact on the determination of the Wb, its effect appears relatively small within a cohort of healthy adults during graded exercise.


Assuntos
Exercício Físico , Pulmão/fisiologia , Modelos Teóricos , Respiração , Músculos Respiratórios/fisiologia , Parede Torácica/fisiologia , Trabalho Respiratório , Adolescente , Adulto , Idoso , Ciclismo , Complacência (Medida de Distensibilidade) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Adulto Jovem
4.
BMJ Case Rep ; 13(12)2020 Dec 13.
Artigo em Inglês | MEDLINE | ID: mdl-33318277

RESUMO

A 59-year-old man presented to the emergency department with recent onset biphasic stridor, dyspnoea and increased work of breathing on the background of prolonged intubation for the novel COVID-19 2 months previously. Flexible laryngoscopy revealed bilateral vocal fold immobility with a soft tissue mass in the interarytenoid region. The patient's symptoms improved with oxygen therapy, nebulised epinephrine (5 mL; 1:10 000) and intravenous dexamethasone (3.3 mg). The following morning, the patient was taken to theatre, underwent suspension microlaryngoscopy and found to have bilateral fixation of the cricoarytenoid joints and a large granuloma in the interarytenoid area. He underwent cold steel resection of the granuloma and balloon dilatation between the arytenoids, with the hope of mobilising the joints. This failed and CO2 laser arytenoidectomy was performed on the left side. The stridor had resolved postoperatively, with normalisation of work of breathing and the patient was discharged home on the first postoperative day.


Assuntos
COVID-19/terapia , Granuloma/cirurgia , Intubação Intratraqueal/efeitos adversos , Doenças da Laringe/cirurgia , Constrição Patológica/etiologia , Constrição Patológica/cirurgia , Dispneia/etiologia , Emergências , Granuloma/etiologia , Humanos , Doenças da Laringe/etiologia , Laringe/patologia , Masculino , Pessoa de Meia-Idade , Sons Respiratórios , SARS-CoV-2 , Trabalho Respiratório
6.
Crit Care ; 24(1): 494, 2020 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-32778136

RESUMO

Deterioration of lung function during the first week of COVID-19 has been observed when patients remain with insufficient respiratory support. Patient self-inflicted lung injury (P-SILI) is theorized as the responsible, but there is not robust experimental and clinical data to support it. Given the limited understanding of P-SILI, we describe the physiological basis of P-SILI and we show experimental data to comprehend the role of regional strain and heterogeneity in lung injury due to increased work of breathing.In addition, we discuss the current approach to respiratory support for COVID-19 under this point of view.


Assuntos
Infecções por Coronavirus/fisiopatologia , Progressão da Doença , Lesão Pulmonar/fisiopatologia , Pneumonia Viral/fisiopatologia , Trabalho Respiratório/fisiologia , Infecções por Coronavirus/terapia , Cuidados Críticos , Humanos , Lesão Pulmonar/etiologia , Pandemias , Pneumonia Viral/terapia , Ensaios Clínicos Controlados Aleatórios como Assunto , Respiração Artificial
7.
Cochrane Database Syst Rev ; 8: CD012977, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32767571

RESUMO

BACKGROUND: Asthma is an illness that commonly affects adults and children, and it serves as a common reason for children to attend emergency departments. An asthma exacerbation is characterised by acute or subacute worsening of shortness of breath, cough, wheezing, and chest tightness and may be triggered by viral respiratory infection, poor compliance with usual medication, a change in the weather, or exposure to allergens or irritants. Most children with asthma have mild or moderate exacerbations and respond well to first-line therapy (inhaled short-acting beta-agonists and systemic corticosteroids). However, the best treatment for the small proportion of seriously ill children who do not respond to first-line therapy is not well understood. Currently, a large number of treatment options are available and there is wide variation in management. OBJECTIVES: Main objective - To summarise Cochrane Reviews with or without meta-analyses of randomised controlled trials on the efficacy and safety of second-line treatment for children with acute exacerbations of asthma (i.e. after first-line treatments, titrated oxygen delivery, and administration of intermittent inhaled short-acting beta2-agonists and oral corticosteroids have been tried and have failed) Secondary objectives - To identify gaps in the current evidence base that will inform recommendations for future research and subsequent Cochrane Reviews - To categorise information on reported outcome measures used in trials of escalation of treatment for acute exacerbations of asthma in children, and to make recommendations for development and reporting of standard outcomes in future trials and reviews - To identify relevant randomised controlled trials that have been published since the date of publication of each included review METHODS: We included Cochrane Reviews assessing interventions for children with acute exacerbations of asthma. We searched the Cochrane Database of Systematic Reviews. The search is current to 28 December 2019. We also identified trials that were potentially eligible for, but were not currently included in, published reviews. We assessed the quality of included reviews using the ROBIS criteria (tool used to assess risk of bias in systematic reviews). We presented an evidence synthesis of data from reviews alongside an evidence map of clinical trials. Primary outcomes were length of stay, hospital admission, intensive care unit admission, and adverse effects. We summarised all findings in the text and reported data for each outcome in 'Additional tables'. MAIN RESULTS: We identified 17 potentially eligible Cochrane Reviews but extracted data from, and rated the quality of, 13 reviews that reported results for children alone. We excluded four reviews as one did not include any randomised controlled trials (RCTs), one did not provide subgroup data for children, and the last two had been updated and replaced by subsequent reviews. The 13 reviews included 67 trials; the number of trials in each review ranged from a single trial up to 27 trials. The vast majority of comparisons included between one and three trials, involving fewer than 100 participants. The total number of participants included in reviews ranged from 40 to 2630. All studies included children; 16 (24%) included children younger than two years of age. Most of the reviews reported search dates older than four years. We have summarised the published evidence as outlined in Cochrane Reviews. Key findings, in terms of our primary outcomes, are that (1) intravenous magnesium sulfate was the only intervention shown to reduce hospital length of stay (high-certainty evidence); (2) no evidence suggested that any intervention reduced the risk of intensive care admission (low- to very low-certainty evidence); (3) the risk of hospital admission was reduced by the addition of inhaled anticholinergic agents to inhaled beta2-agonists (moderate-certainty evidence), the use of intravenous magnesium sulfate (high-certainty evidence), and the use of inhaled heliox (low-certainty evidence); (4) the addition of inhaled magnesium sulfate to usual bronchodilator therapy appears to reduce serious adverse events during hospital admission (moderate-certainty evidence); (5) aminophylline increased vomiting compared to placebo (moderate-certainty evidence) and increased nausea and nausea/vomiting compared to intravenous beta2-agonists (low-certainty evidence); and (6) the addition of anticholinergic therapy to short-acting beta2-agonists appeared to reduce the risk of nausea (high-certainty evidence) and tremor (moderate-certainty evidence) but not vomiting (low-certainty evidence). We considered 4 of the 13 reviews to be at high risk of bias based on the ROBIS framework. In all cases, this was due to concerns regarding identification and selection of studies. The certainty of evidence varied widely (by review and also by outcome) and ranged from very low to high. AUTHORS' CONCLUSIONS: This overview provides the most up-to-date evidence on interventions for escalation of therapy for acute exacerbations of asthma in children from Cochrane Reviews of randomised controlled trials. A vast majority of comparisons involved between one and three trials and fewer than 100 participants, making it difficult to assess the balance between benefits and potential harms. Due to the lack of comparative studies between various treatment options, we are unable to make firm practice recommendations. Intravenous magnesium sulfate appears to reduce both hospital length of stay and the risk of hospital admission. Hospital admission is also reduced with the addition of inhaled anticholinergic agents to inhaled beta2-agonists. However, further research is required to determine which patients are most likely to benefit from these therapies. Due to the relatively rare incidence of acute severe paediatric asthma, multi-centre research will be required to generate high-quality evidence. A number of existing Cochrane Reviews should be updated, and we recommend that a new review be conducted on the use of high-flow nasal oxygen therapy. Important priorities include development of an internationally agreed core outcome set for future trials in acute severe asthma exacerbations and determination of clinically important differences in these outcomes, which can then inform adequately powered future trials.


Assuntos
Antiasmáticos/uso terapêutico , Asma/terapia , Broncodilatadores/uso terapêutico , Progressão da Doença , Revisões Sistemáticas como Assunto , Doença Aguda , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/uso terapêutico , Aminofilina/administração & dosagem , Aminofilina/efeitos adversos , Antiasmáticos/administração & dosagem , Antibacterianos/uso terapêutico , Asma/tratamento farmacológico , Viés , Broncodilatadores/administração & dosagem , Criança , Pré-Escolar , Antagonistas Colinérgicos/uso terapêutico , Hélio , Humanos , Lactente , Tempo de Internação , Antagonistas de Leucotrienos/uso terapêutico , Sulfato de Magnésio/administração & dosagem , Sulfato de Magnésio/efeitos adversos , Sulfato de Magnésio/uso terapêutico , Náusea/induzido quimicamente , Náusea/prevenção & controle , Oxigênio/administração & dosagem , Respiração com Pressão Positiva , Ensaios Clínicos Controlados Aleatórios como Assunto , Vômito/induzido quimicamente , Trabalho Respiratório/efeitos dos fármacos
9.
Univ. salud ; 22(2): 102-111, mayo-ago. 2020. tab, graf
Artigo em Espanhol | LILACS, COLNAL | ID: biblio-1115959

RESUMO

Introducción: La cánula nasal de alto flujo en adultos ofrece un tratamiento alternativo a la oxigenoterapia convencional. Objetivo: Establecer el comportamiento clínico y gasométrico de pacientes con falla respiratoria aguda que habitan a 2.600 msnm, tratados con cánula nasal de alto flujo en cuidado intensivo adulto. Materiales y métodos: Estudio piloto cuasi experimental pretest-postest intrasujeto, tamaño de muestra 14 pacientes calculado a través de Epidat. Tipo de muestreo no probabilístico por conveniencia, durante catorce meses. Resultados: El 78% de los pacientes fueron mujeres, la edad promedio fue 68 años, y el diagnóstico principal fue enfermedad pulmonar obstructiva crónica (EPOC) en el 71,42% de los casos. Se administró un flujo de oxígeno promedio de 30 Lt/min para pacientes con (EPOC), para el resto de diagnósticos se programaron flujos mayores. El trabajo respiratorio disminuyó posterior al uso de cánula nasal de alto flujo, la presión arterial de oxígeno mejoró paulatinamente en pacientes con falla hipoxémica y el índice de oxigenación incrementó progresivamente en los dos tipos de falla respiratoria. Conclusiones: La cánula nasal de alto flujo es una opción terapéutica útil en el manejo de la falla respiratoria aguda a 2.600 msnm, permitiendo mejoría de la oxigenación y disminución del trabajo respiratorio.


Introduction: High-flow nasal cannula offers an alternative treatment approach to conventional oxygen therapy in adults. Objective: To establish the clinical and gasometric behavior of patients with acute respiratory failure who live at 2,600 m.a.s.l. and are treated with high-flow nasal cannula in an adult intensive care unit. Materials and methods: Quasi-experimental pilot study with a pretest-posttest within-subject design and a sample size of 14 patients calculated through Epidat. A non-probabilistic convenience sampling was conducted for fourteen months. Results: 78% of the patients were women and their average age was 68 years. Chronic Obstructive Pulmonary Disease (COPD) was diagnosed in 71.42% of the cases. An oxygen flow rate of 30 L/min was administered to patients with Chronic Obstructive Pulmonary Disease, while higher rates were used for the rest of the diagnoses. Nasal cannula treatment led to (i) a decreased respiratory function, (ii) a gradually improved arterial blood pressure in patients with hypoxemic failure, (iii) and a progressively increased oxygenation rate. Conclusions: High-flow nasal cannula is a useful therapeutic option in the management of patients with acute respiratory failure living at 2,600 m.a.s.l. because it improves oxygenation and reduces respiratory function.


Assuntos
Insuficiência Respiratória , Cânula , Gasometria , Trabalho Respiratório , Doença Pulmonar Obstrutiva Crônica
10.
Arch Dis Child Fetal Neonatal Ed ; 105(6): 669-671, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32669360

RESUMO

BACKGROUND: The COVID-19 pandemic has raised concern for healthcare workers getting infected via aerosol from non-invasive respiratory support of infants. Attaching filters that remove viral particles in air from the expiratory limb of continuous positive airway pressure (CPAP) devices should theoretically decrease the risk. However, adding filters to the expiratory limb could add to expiratory resistance and thereby increase the imposed work of breathing (WOB). OBJECTIVE: To evaluate the effects on imposed WOB when attaching filters to the expiratory limb of CPAP devices. METHODS: Two filters were tested on three CPAP systems at two levels of CPAP in a mechanical lung model. Main outcome was imposed WOB. RESULTS: There was a minor increase in imposed WOB when attaching the filters. The differences between the two filters were small. CONCLUSION: To minimise contaminated aerosol generation during CPAP treatment, filters can be attached to expiratory tubing with only a minimal increase in imposed WOB in a non-humidified environment. Care has to be taken to avoid filter obstruction and replace filters as recommended.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/instrumentação , Infecções por Coronavirus/prevenção & controle , Filtração/instrumentação , Controle de Infecções/instrumentação , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Betacoronavirus , Expiração/fisiologia , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Modelos Anatômicos , Trabalho Respiratório/fisiologia
11.
Br J Anaesth ; 125(1): e148-e157, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32386831

RESUMO

BACKGROUND: Bedside measures of patient effort are essential to properly titrate the level of pressure support ventilation. We investigated whether the tidal swing in oesophageal (ΔPes) and transdiaphragmatic pressure (ΔPdi), and ultrasonographic changes in diaphragm (TFdi) and parasternal intercostal (TFic) thickening are reliable estimates of respiratory effort. The effect of diaphragm dysfunction was also considered. METHODS: Twenty-one critically ill patients were enrolled: age 73 (14) yr, BMI 27 (7) kg m-2, and Pao2/Fio2 33.3 (9.2) kPa. A three-level pressure support trial was performed: baseline, 25% (PS-medium), and 50% reduction (PS-low). We recorded the oesophageal and transdiaphragmatic pressure-time products (PTPs), work of breathing (WOB), and diaphragm and intercostal ultrasonography. Diaphragm dysfunction was defined by the Gilbert index. RESULTS: Pressure support was 9.0 (1.6) cm H2O at baseline, 6.7 (1.3) (PS-medium), and 4.4 (1.0) (PS-low). ΔPes was significantly associated with the oesophageal PTP (R2=0.868; P<0.001) and the WOB (R2=0.683; P<0.001). ΔPdi was significantly associated with the transdiaphragmatic PTP (R2=0.820; P<0.001). TFdi was only weakly correlated with the oesophageal PTP (R2=0.326; P<0.001), and the correlation improved after excluding patients with diaphragm dysfunction (R2=0.887; P<0.001). TFdi was higher and TFic lower in patients without diaphragm dysfunction: 33.6 (18.2)% vs 13.2 (9.2)% and 2.1 (1.7)% vs 12.7 (9.1)%; P<0.0001. CONCLUSIONS: ΔPes and ΔPdi are adequate estimates of inspiratory effort. Diaphragm ultrasonography is a reliable indicator of inspiratory effort in the absence of diaphragm dysfunction. Additional measurement of parasternal intercostal thickening may discriminate a low inspiratory effort or a high effort in the presence of a dysfunctional diaphragm.


Assuntos
Esôfago/fisiologia , Respiração com Pressão Positiva/métodos , Músculos Respiratórios/fisiologia , Ultrassonografia/métodos , Trabalho Respiratório/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Cuidados Críticos/métodos , Estado Terminal , Diafragma/fisiologia , Esôfago/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculos Respiratórios/diagnóstico por imagem
14.
Sci Rep ; 10(1): 3755, 2020 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-32111935

RESUMO

This study's objective was the generation of a standardized geometry of the healthy nasal cavity. An average geometry of the healthy nasal cavity was generated using a statistical shape model based on 25 symptom-free subjects. Airflow within the average geometry and these geometries was calculated using fluid simulations. Integral measures of the nasal resistance, wall shear stresses (WSS) and velocities were calculated as well as cross-sectional areas (CSA). Furthermore, individual WSS and static pressure distributions were mapped onto the average geometry. The average geometry featured an overall more regular shape that resulted in less resistance, reduced WSS and velocities compared to the median of the 25 geometries. Spatial distributions of WSS and pressure of the average geometry agreed well compared to the average distributions of all individual geometries. The minimal CSA of the average geometry was larger than the median of all individual geometries (83.4 vs. 74.7 mm²). The airflow observed within the average geometry of the healthy nasal cavity did not equal the average airflow of the individual geometries. While differences observed for integral measures were notable, the calculated values for the average geometry lay within the distributions of the individual parameters. Spatially resolved parameters differed less prominently.


Assuntos
Algoritmos , Modelos Biológicos , Cavidade Nasal , Tomografia Computadorizada por Raios X , Trabalho Respiratório/fisiologia , Adulto , Feminino , Humanos , Masculino , Cavidade Nasal/diagnóstico por imagem , Cavidade Nasal/fisiologia , Estudos Retrospectivos
15.
Crit Care ; 24(1): 85, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32164784

RESUMO

BACKGROUND: Diaphragm atrophy and dysfunction are consequences of mechanical ventilation and are determinants of clinical outcomes. We hypothesize that partial preservation of diaphragm function, such as during assisted modes of ventilation, will restore diaphragm thickness. We also aim to correlate the changes in diaphragm thickness and function to outcomes and clinical factors. METHODS: This is a prospective, multicentre, observational study. Patients mechanically ventilated for more than 48 h in controlled mode and eventually switched to assisted ventilation were enrolled. Diaphragm ultrasound and clinical data collection were performed every 48 h until discharge or death. A threshold of 10% was used to define thinning during controlled and recovery of thickness during assisted ventilation. Patients were also classified based on the level of diaphragm activity during assisted ventilation. We evaluated the association between changes in diaphragm thickness and activity and clinical outcomes and data, such as ventilation parameters. RESULTS: Sixty-two patients ventilated in controlled mode and then switched to the assisted mode of ventilation were enrolled. Diaphragm thickness significantly decreased during controlled ventilation (1.84 ± 0.44 to 1.49 ± 0.37 mm, p < 0.001) and was partially restored during assisted ventilation (1.49 ± 0.37 to 1.75 ± 0.43 mm, p < 0.001). A diaphragm thinning of more than 10% was associated with longer duration of controlled ventilation (10 [5, 15] versus 5 [4, 8.5] days, p = 0.004) and higher PEEP levels (12.6 ± 4 versus 10.4 ± 4 cmH2O, p = 0.034). An increase in diaphragm thickness of more than 10% during assisted ventilation was not associated with any clinical outcome but with lower respiratory rate (16.7 ± 3.2 versus 19.2 ± 4 bpm, p = 0.019) and Rapid Shallow Breathing Index (37 ± 11 versus 44 ± 13, p = 0.029) and with higher Pressure Muscle Index (2 [0.5, 3] versus 0.4 [0, 1.9], p = 0.024). Change in diaphragm thickness was not related to diaphragm function expressed as diaphragm thickening fraction. CONCLUSION: Mode of ventilation affects diaphragm thickness, and preservation of diaphragmatic contraction, as during assisted modes, can partially reverse the muscle atrophy process. Avoiding a strenuous inspiratory work, as measured by Rapid Shallow Breathing Index and Pressure Muscle Index, may help diaphragm thickness restoration.


Assuntos
Diafragma/diagnóstico por imagem , Respiração Artificial/efeitos adversos , Insuficiência Respiratória/terapia , Ultrassonografia/métodos , Trabalho Respiratório , Estado Terminal , Diafragma/patologia , Diafragma/fisiopatologia , Feminino , Humanos , Unidades de Terapia Intensiva , Masculino , Pessoa de Meia-Idade , Contração Muscular/fisiologia , Debilidade Muscular/diagnóstico por imagem , Estudos Prospectivos , Insuficiência Respiratória/patologia
16.
Am J Respir Crit Care Med ; 201(9): 1086-1098, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32097569

RESUMO

Rationale: Monitoring and controlling respiratory drive and effort may help to minimize lung and diaphragm injury. Airway occlusion pressure (P0.1) is a noninvasive measure of respiratory drive.Objectives: To determine 1) the validity of "ventilator" P0.1 (P0.1vent) displayed on the screen as a measure of drive, 2) the ability of P0.1 to detect potentially injurious levels of effort, and 3) how P0.1vent displayed by different ventilators compares to a "reference" P0.1 (P0.1ref) measured from airway pressure recording during an occlusion.Methods: Analysis of three studies in patients, one in healthy subjects, under assisted ventilation, and a bench study with six ventilators. P0.1vent was validated against measures of drive (electrical activity of the diaphragm and muscular pressure over time) and P0.1ref. Performance of P0.1ref and P0.1vent to detect predefined potentially injurious effort was tested using derivation and validation datasets using esophageal pressure-time product as the reference standard.Measurements and Main Results: P0.1vent correlated well with measures of drive and with the esophageal pressure-time product (within-subjects R2 = 0.8). P0.1ref >3.5 cm H2O was 80% sensitive and 77% specific for detecting high effort (≥200 cm H2O ⋅ s ⋅ min-1); P0.1ref ≤1.0 cm H2O was 100% sensitive and 92% specific for low effort (≤50 cm H2O ⋅ s ⋅ min-1). The area under the receiver operating characteristics curve for P0.1vent to detect potentially high and low effort were 0.81 and 0.92, respectively. Bench experiments showed a low mean bias for P0.1vent compared with P0.1ref for most ventilators but precision varied; in patients, precision was lower. Ventilators estimating P0.1vent without occlusions could underestimate P0.1ref.Conclusions: P0.1 is a reliable bedside tool to assess respiratory drive and detect potentially injurious inspiratory effort.


Assuntos
Pressão do Ar , Monitoramento Biológico/normas , Inalação/fisiologia , Respiração com Pressão Positiva/normas , Guias de Prática Clínica como Assunto , Respiração Artificial/normas , Trabalho Respiratório/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes
17.
Arch Dis Child Fetal Neonatal Ed ; 105(5): 550-554, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32047029

RESUMO

BACKGROUND: The original bubble continuous positive airway pressure (bCPAP) design has wide-bore tubing and a low-resistance interface. This creates a stable airway pressure that is reflected by the submersion depth of the expiratory tubing. Several systems with alterations to the original bCPAP design are now available. Most of these are aimed for use in low-income and middle-income countries and have not been compared with the original design. OBJECTIVE: We identified three major alterations to the original bCPAP design: (1) resistance of nasal interface, (2) volume of dead space and (3) diameter of expiratory tubing. Our aim was to study the effect of these alterations on CPAP delivery and work of breathing in a mechanical lung model. Dead space should always be avoided and was not further tested. METHODS: The effect of nasal interface resistance and expiratory tubing diameter was evaluated with simulated breathing in a mechanical lung model without interface leakage. The main outcome was delivered CPAP and imposed work of breathing. RESULTS: High-resistance interfaces and narrow expiratory tubing increased the work of breathing. Additionally, narrow expiratory tubing resulted in higher CPAP levels than indicated by the submersion depth. CONCLUSION: Our study shows the significant effect on CPAP delivery and imposed work of breathing when using high-resistance interfaces and narrow expiratory tubing in bCPAP systems. New systems should include low-resistance interfaces and wide-bore tubing and be compared with the original bCPAP. Referring to all systems that bubble as bCPAP is misleading and potentially hazardous.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/instrumentação , Pressão Positiva Contínua nas Vias Aéreas/métodos , Trabalho Respiratório/fisiologia , Resistência das Vias Respiratórias/fisiologia , Humanos , Recém-Nascido , Modelos Biológicos
18.
PLoS One ; 15(1): e0226980, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923192

RESUMO

RATIONALE: Pulmonary function testing (PFT) provides diagnostic information regarding respiratory physiology. However, many forms of PFT are time-intensive and require patient cooperation. Respiratory inductance plethysmography (RIP) provides thoracoabdominal asynchrony (TAA) and work of breathing (WOB) data. pneuRIPTM is a noninvasive, wireless analyzer that provides real-time assessment of RIP via an iPad. In this study, we show that pneuRIPTM can be used in a hospital clinic setting to differentiate WOB indices and breathing patterns in children with DMD as compared to age-matched healthy subjects. METHODS: RIP using the pneuRIPTM was conducted on 9 healthy volunteers and 7 DMD participants (ages 5-18) recruited from the neuromuscular clinic, under normal resting conditions over 3-5 min during routine outpatient visits. The tests were completed in less than 10 minutes and did not add excessive time to the clinic visit. Variables recorded included labored-breathing index (LBI), phase angle (Φ) between abdomen and rib cage, respiratory rate (RR), percentage of rib cage input (RC%), and heart rate (HR). The data were displayed in histogram plots to identify distribution patterns within the normal ranges. The percentages of data within the ranges (0≤ Φ ≤30 deg.; median RC %±10%; median RR±5%; 1≤LBI≤1.1) were compared. Unpaired t-tests determined significance of the data between groups. RESULTS: 100% patient compliance demonstrates the feasibility of such testing in clinical settings. DMD patients showed a significant elevation in Φ, LBI, and HR averages (P<0.006, P<0.002, P<0.046, respectively). Healthy subjects and DMD patients had similar BPM and RC% averages. All DMD data distributions were statistically different from healthy subjects based on analysis of histograms. The DMD patients showed significantly less data within the normal ranges, with only 49.7% Φ, 48.0% RC%, 69.2% RR, and 50.7% LBI. CONCLUSION: In this study, noninvasive pneuRIPTM testing provided instantaneous PFT diagnostic results. As compared to healthy subjects, patients with DMD showed abnormal results with increased markers of TAA, WOB indices, and different breathing patterns. These results are similar to previous studies evaluating RIP in preterm infants. Further studies are needed to compare these results to other pulmonary testing methods. The pneuRIPTM testing approach provides immediate diagnostic information in outpatient settings.


Assuntos
Distrofia Muscular de Duchenne/fisiopatologia , Pletismografia/instrumentação , Mecânica Respiratória , Trabalho Respiratório , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Frequência Cardíaca , Humanos , Masculino , Distrofia Muscular de Duchenne/diagnóstico , Pletismografia/métodos , Testes de Função Respiratória , Taxa Respiratória
19.
Pneumologie ; 74(3): 137-148, 2020 Mar.
Artigo em Alemão | MEDLINE | ID: mdl-31918445

RESUMO

Nasal high-flow provides a stable oxygenation in acute hypoxemic respiratory failure, modifies breathing patterns, reduces work of breathing and can decrease hypercapnia. Thereby NHF provides more features than low-flow oxygen and acts as a ventilatory support device. Different studies show benefits of NHF compared to NIV. For these reasons we will discuss the capabilities of NHF and NIV in selected settings.


Assuntos
Pulmão/fisiopatologia , Ventilação não Invasiva/métodos , Oxigenoterapia/métodos , Oxigênio/administração & dosagem , Respiração com Pressão Positiva/métodos , Insuficiência Respiratória/terapia , Trabalho Respiratório/fisiologia , Humanos , Hipercapnia/prevenção & controle , Resultado do Tratamento
20.
Pediatr Pulmonol ; 55(3): 616-623, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31868983

RESUMO

OBJECTIVE: To investigate the relationship between applied flows of nasal high flow (NHF) and physiological outcomes and work of breathing (WOB), to identify an optimal delivery flow which results in reduced WOB in preterm infants. DESIGN: A prospective observational clinical study with randomly applied NHF rates. PATIENTS AND SETTING: Preterm infants within 72 hours of commencement of NHF respiratory support. INTERVENTIONS: Infants were initially placed on 8 L/min of NHF and flows of 2, 4, and 6 L/min were then applied in random order. MEASUREMENTS AND RESULTS: WOB was measured using transcutaneous electromyography and respiratory inductance plethysmography. Physiological variables were also recorded. Measurements taken 10 minutes after each flow change were compared with 8 L/min. Sixteen infants with a median gestational age of 28 (range 24-31) weeks and postnatal age of 14 (2-55) days were included in the study. The median flow rate before the study was 6 (4-8) L/min and a fraction of inspired oxygen (FiO2 ) was 0.21 (0.21-0.26). Changes in flow resulted in changes in activity in the front diaphragm (P = .027) and intercostals (P = .034). The electrical activity of the front diaphragm at 8 L/min was significantly lower than that at 2 L/min (P = .016). Respiratory rate was lowest at 6 L/min (P = .002) and SpO2 /FiO2 was highest at 8 L/min (P < .04). CONCLUSION: In preterm infants, changes in WOB resulting from randomly applied levels of NHF can be demonstrated by measuring the electrical activity of the diaphragm and intercostal muscles with transcutaneous electromyography. In combination with physiological measurements, the similarities in electrical activity between 4, 6, and 8 L/min suggest that these three flows may be equally as effective.


Assuntos
Recém-Nascido Prematuro/fisiologia , Nariz/fisiologia , Oxigenoterapia , Diafragma/fisiologia , Eletromiografia , Feminino , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Masculino , Pletismografia , Taxa Respiratória , Trabalho Respiratório
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