RESUMO
OBJECTIVES: To identify short-term repeatability of forced oscillation technique (FOT) measurement of lung function, assess the lung function response to bronchodilators (BDs) by FOT, and prove the concept that only some very preterm infants manifest a change in lung mechanics in response to BD. STUDY DESIGN: We retrospectively analyzed respiratory system resistance and respiratory system reactance measured by FOT (Fabian HFOi). The measurement short-term repeatability was assessed in 43 patients on 60 occasions; BD responsiveness was assessed using a different data set, including 38 measurements in 18 infants. The coefficient of repeatability was calculated as twice the SD of differences between measurements performed 15 minutes apart. We assessed BD responsiveness by measuring respiratory system resistance and respiratory system reactance before and 15 minutes after administering 200 mcg/kg of nebulized salbutamol. A positive response was defined as an improvement in respiratory system resistance or respiratory system reactance greater than the identified coefficient of repeatability. RESULTS: The coefficient of repeatability was 7.5 cmH2O∗s/L (21%) for respiratory system resistance and 6.3 cmH2O∗s/L (21%) for respiratory system reactance. On average, respiratory system resistance did not change significantly following BD administration, though respiratory system reactance increased significantly (from -32.0 [-50.2, -24.4] to -27.9 [-38.1, -22.0] cmH2O∗s/L, P < .001). Changes in respiratory system resistance or respiratory system reactance after BD were greater than the identified coefficient of repeatability in 8 infants (44%) on 13 (34%) occasions. CONCLUSIONS: We identified a threshold to assess BD responsiveness by FOT in preterm infants. We speculate that FOT could be used to assess and personalize treatment with BD.
Assuntos
Resistência das Vias Respiratórias , Broncodilatadores , Lactente , Humanos , Recém-Nascido , Broncodilatadores/uso terapêutico , Estudos Retrospectivos , Resistência das Vias Respiratórias/fisiologia , Recém-Nascido Prematuro , Testes de Função Respiratória/métodos , Mecânica RespiratóriaRESUMO
OBJECTIVES: To assess the feasibility of volumetric capnography in spontaneously breathing very preterm infants at 36 weeks postmenstrual age (PMA) and its association with clinical markers of lung disease including the duration of respiratory support and bronchopulmonary dysplasia (BPD). STUDY DESIGN: We obtained mainstream volumetric capnography measurements in 143 very preterm infants at 36 weeks PMA. BPD was categorized into no, mild, moderate, and severe according to the 2001 National Heart, Lung and Blood Institute workshop report. Normalized capnographic slopes of phase II (SnII) and phase III (SnIII) were calculated. We assessed the effect of BPD, duration of respiratory support, and duration of supplemental oxygen on capnographic slopes. RESULTS: SnIII was steeper in infants with moderate to severe BPD (76 ± 25/L) compared with mild (31 ± 20/L) or no BPD (26 ± 18/L) (P < .001). The association of SnIII with moderate to severe BPD persisted after adjusting for birth weight z-score, respiratory rate, and airway dead space to tidal volume ratio. The diagnostic usefulness of SnIII to discriminate between infants with and without moderate to severe BPD was high (area under the curve, 0.94; 95% CI, 0.89-0.99). CONCLUSIONS: Volumetric capnography is feasible in spontaneously breathing preterm infants at 36 weeks PMA and reflects the degree of lung disease. This promising bedside lung function technique may offer an objective, continuous physiological outcome measure for assessment of BPD severity. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02083562.
Assuntos
Displasia Broncopulmonar/terapia , Capnografia , Recém-Nascido Prematuro , Respiração Artificial , Índice de Gravidade de Doença , Estudos de Viabilidade , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Recém-Nascido de muito Baixo Peso , Masculino , Sistemas Automatizados de Assistência Junto ao Leito , Estudos ProspectivosRESUMO
OBJECTIVES: To investigate, in infants born preterm with or without bronchopulmonary dysplasia (BPD), the trajectory of tidal breathing flow-volume (TBFV) parameters in the first 2 years of life; the association between TBFV parameters and perinatal risk factors; and the predictive value of TBFV parameters for rehospitalizations due to respiratory infections and wheeze. STUDY DESIGN: We retrospectively analyzed TBFV measurements performed at 0-6, 6-12, and 12-24 months of corrected age in 97 infants <32 weeks of gestation and <1500 g. We assessed the association between TBFV parameters and perinatal risk-factors using linear regressions and the predictive capacity for subsequent respiratory morbidity using logistic regressions. We used the area under the curve and likelihood ratio test (LRT) to compare nested models. RESULTS: Time to peak tidal expiratory flow/expiratory time ratio (tPTEF/tE) was lower than normal for the first 2 years of corrected age. Longer duration of oxygen supplementation, intubation, and respiratory support were associated with reduced tPTEF/tE at all time points. For each z-score increase in tPTEF/tE, the OR for rehospitalizations decreased by 0.70. tPTEF/tE added significantly to BPD classifications alone in predicting rehospitalizations (area under the receiver operating characteristic curve = 0.81 vs 0.76, P value for LRT = .0012), and wheeze (area under the receiver operating characteristic curve = 0.76 vs 0.71, P value for LRT <.001). CONCLUSIONS: Infants born preterm, with and without BPD, display persistent airway obstruction during the first 2 years of life. tPTEF/tE may identify infants at greater risk of severe respiratory morbidity.
Assuntos
Displasia Broncopulmonar/fisiopatologia , Feminino , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Estudos Longitudinais , Masculino , Respiração , Estudos Retrospectivos , Volume de Ventilação Pulmonar/fisiologiaRESUMO
OBJECTIVE: To test whether low variability of tidal volume (VT) and capnographic indices are predictive of subsequent respiratory morbidity in preterm infants. STUDY DESIGN: In a birth cohort of 133 preterm infants, lung function was performed at 44 weeks postmenstrual age. Associations between the coefficient of variation (CV) of VT (CVVT) and of expired CO2 volume per breath (CVVE,CO2) with rehospitalization, wheeze, and inhalation therapy during infancy were assessed using logistic regression. Area under the curve (AUC) analysis was used to assess whether outcome prediction using bronchopulmonary dysplasia (BPD) classification was enhanced by CVVT or CVVE,CO2. RESULTS: For each IQR decrease in CVVT (range, 4%-35%) and CVVE,CO2 (range, 5%-40%), the OR for rehospitalization increased by 2.25 (95% CI, 1.21-4.20) and 2.31 (95% CI, 1.20-4.45), respectively. The predictive value of BPD for rehospitalization was improved when CVVT or CVVE,CO2 was added to the model, with the AUC increasing from 0.56 to 0.66 in both models. No association was found for the other outcomes. CONCLUSIONS: Compared with BPD classification alone, including near-term variability of tidal breathing parameters improves the prediction of rehospitalization in infancy. These findings may inform parent counseling and monitoring strategies in preterm infants.
Assuntos
Displasia Broncopulmonar/fisiopatologia , Pulmão/fisiopatologia , Volume de Ventilação Pulmonar/fisiologia , Capnografia/métodos , Feminino , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Recém-Nascido Prematuro , Modelos Logísticos , Masculino , Readmissão do Paciente , Estudos Prospectivos , Curva ROC , Respiração Artificial/métodos , Respiração Artificial/estatística & dados numéricos , Testes de Função Respiratória/métodos , Taxa Respiratória , Fatores de Risco , Índice de Gravidade de DoençaRESUMO
OBJECTIVE: To characterize changes in lung mechanics and right ventricular output (RVO) during incremental/decremental continuous distending pressure (CDP) maneuvers in newborn infants receiving high-frequency oscillatory ventilation, with the aim of evaluating when open lung maneuvers are needed and whether they are beneficial. STUDY DESIGN: Thirteen infants on high-frequency oscillatory ventilation were studied with a median (IQR) gestational age of 261 (253-291) weeks and median (IQR) body weight of 810 (600-1020) g. CDP was increased stepwise from 8 cmH2O to a maximum pressure and subsequently decreased until oxygenation deteriorated or a CDP of 8 cmH2O was reached. The lowest CDP that maintained good oxygenation was considered the clinically optimal CDP. At each CDP, the following variables were evaluated: oxygenation, respiratory system reactance (Xrs), and RVO by Doppler echocardiography. RESULTS: At maximal CDP reached during the trial, 19 [1] cmH2O (mean [SEM]), oxygenation markedly improved, and Xrs and RVO decreased. During deflation, oxygenation remained stable over a wide range of CDP settings, Xrs returned to the baseline values, and RVO increased but the baseline values were not readily restored in all patients. CONCLUSION: These results suggest that Xrs and RVO are more sensitive than oxygenation to overdistension and they may be useful in clinical practice to guide open lung maneuvers.