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AIMS: Cerebral amyloid angiopathy (CAA)-related inflammation (CAA-RI) is a potentially reversible manifestation of CAA, histopathologically characterised by transmural and/or perivascular inflammatory infiltrates. We aimed to identify clinical, radiological and laboratory variables capable of improving or supporting the diagnosis of or predicting/influencing the prognosis of CAA-RI and to retrospectively evaluate different therapeutic approaches. METHODS: We present clinical and neuroradiological observations in seven unpublished CAA-RI cases, including neuropathological findings in two definite cases. These cases were included in a systematic analysis of probable/definite CAA-RI cases published in the literature up to 31 December 2021. Descriptive and associative analyses were performed, including a set of clinical, radiological and laboratory variables to predict short-term, 6-month and 1-year outcomes and mortality, first on definite and second on an expanded probable/definite CAA-RI cohort. RESULTS: Data on 205 definite and 100 probable cases were analysed. CAA-RI had a younger symptomatic onset than non-inflammatory CAA, without sex preference. Transmural histology was more likely to be associated with the co-localisation of microbleeds with confluent white matter hyperintensities on magnetic resonance imaging (MRI). Incorporating leptomeningeal enhancement and/or sulcal non-nulling on fluid-attenuated inversion recovery (FLAIR) enhanced the sensitivity of the criteria. Cerebrospinal fluid pleocytosis was associated with a decreased probability of clinical improvement and longer term positive outcomes. Future lobar haemorrhage was associated with adverse outcomes, including mortality. Immunosuppression was associated with short-term improvement, with less clear effects on long-term outcomes. The superiority of high-dose over low-dose corticosteroids was not established. CONCLUSIONS: This is the largest retrospective associative analysis of published CAA-RI cases and the first to include an expanded probable/definite cohort to identify diagnostic/prognostic markers. We propose points for further crystallisation of the criteria and directions for future prospective studies.
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Angiopatia Amiloide Cerebral , Humanos , Angiopatia Amiloide Cerebral/complicações , Angiopatia Amiloide Cerebral/diagnóstico , Angiopatia Amiloide Cerebral/patologia , Hemorragia Cerebral , Inflamação/patologia , Imageamento por Ressonância Magnética , Prognóstico , Estudos Prospectivos , Estudos RetrospectivosRESUMO
Sarcoidosis is an inflammatory multisystemic disease of unknown etiology characterized by the formation of non-caseating granulomas. Sarcoidosis can affect any organ, predominantly the lungs, lymphatic system, skin and eyes. While > 90% of patients with sarcoidosis have lung involvement, an estimated 5% of patients with sarcoidosis have clinically manifest cardiac sarcoidosis (CS), whereas approximately 25% have asymptomatic, clinically silent cardiac involvement verified by autopsy or imaging studies. CS can present with conduction disturbances, ventricular arrhythmias, heart failure or sudden cardiac death. Approximately 30% of < 60-year-old patients presenting with unexplained high degree atrioventricular (AV) block or ventricular tachycardia are diagnosed with CS, therefore CS should be strongly considered in such patients. CS is the second leading cause of death among patients affected by sarcoidosis after pulmonary sarcoidosis, therefore its early recognition is important, because early treatment may prevent death from cardiovascular involvement. The establishment of isolated CS diagnosis sometimes can be quite difficult, when extracardiac disease cannot be verified. The other reason for the difficulty to diagnose CS is that CS is a chameleon of cardiology and it can mimic (completely or almost completely) different cardiac diseases, such as arrhythmogenic cardiomyopathy, giant cell myocarditis, dilated, restrictive and hypertrophic cardiomyopathies. In this review article we will discuss the current diagnosis and management of CS and delineate the potential difficulties and pitfalls of establishing the diagnosis in atypical cases of isolated CS.
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IgG4-related (IgG4-RD) disease is a relatively newly identified, chronic autoimmune disorder that can affect any organ system. The disease is relatively rare. It has mostly systemic presentation, however it can also appear in isolated form in one single organ. In our report, we demonstrate an elderly male patient's case with IgG4-RD presented in the form of diffuse meningeal inflammation and hypertrophic pachymeningitis with one-sided cranial nerve and intraventricular involvement.
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Doença Relacionada a Imunoglobulina G4 , Meningite , Humanos , Masculino , Idoso , Doença Relacionada a Imunoglobulina G4/complicações , Doença Relacionada a Imunoglobulina G4/diagnóstico , Imunoglobulina G , Hipertrofia , Inflamação , Nervos Cranianos , Imageamento por Ressonância MagnéticaRESUMO
CANOMAD (chronic ataxic neuropathy, ophthalmoplegia, M-protein agglutination, disialosyl antibodies) syndrome is a rare polyneuropathy. IgM paraproteins react with ganglioside-containing disialylated epitopes resulting in dorsal root ganglionopathy and B-lymphocyte infiltration of cranial and peripheral nerves. Clinical features include ataxia, slight muscle weakness, areflexia, sensory- and cranial nerve symptoms. Case studies have reported the efficacy of rituximab and intravenous immunoglobulin (IVIg) treatments. We present the case of a 57-year-old man, who had difficulty walking, with numbness and clumsiness in all limbs. He had areflexia, vibratory sensation loss and ataxia. Laboratory tests showed IgM monoclonal components and disialosyl antibodies in the serum. Nerve conduction studies indicated severe sensorimotor demyelinating polyneuroradiculopathy. Despite IVIg and rituximab treatments, the patient's disease course gradually worsened and he died of respiratory failure. Neuropathological examination revealed dorsal column- and dorsal root atrophy with mixed mononuclear cell infiltration. This article aims to draw attention to this syndrome, and the use of early potent immunosuppressive treatment to improve patients' quality of life.
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Anemia Hemolítica Autoimune , Ataxia , Oftalmoplegia , Insuficiência Respiratória , Evolução Fatal , Humanos , Masculino , Pessoa de Meia-Idade , Polineuropatias , Qualidade de VidaRESUMO
Lower respiratory tract illness (LRTI) is a leading cause of mortality and morbidity in children. Sensitive and noninvasive infant lung function techniques are needed to measure risk for and impact of LRTI on lung health. The objective of this study was to investigate whether lung function derived from the intra-breath forced oscillation technique (FOT) was able to identify healthy infants at risk of LRTI in the first year of life.Lung function was measured with the novel intra-breath FOT, in 6-week-old infants in a South African birth cohort (Drakenstein Child Health Study). LRTI during the first year was confirmed by study staff. The association between baseline lung function and LRTI was assessed with logistic regression and odds ratios determined using optimal cut-off values.Of the 627 healthy infants with successful lung function testing, 161 (24%) had 238 LRTI episodes subsequently during the first year. Volume dependence of respiratory resistance (ΔR) and reactance (ΔX) was associated with LRTI. The predictive value was stronger if LRTI was recurrent (n=50 (31%): OR 2.5, ΔX), required hospitalisation (n=38 (16%): OR 5.4, ΔR) or was associated with wheeze (n=87 (37%): OR 3.9, ΔX).Intra-breath FOT can identify healthy infants at risk of developing LRTI, wheezing or severe illness in the first year of life.
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Pulmão/fisiopatologia , Testes de Função Respiratória , Mecânica Respiratória , Infecções Respiratórias/fisiopatologia , Antropometria , Feminino , Humanos , Lactente , Masculino , Morbidade , Razão de Chances , Oscilometria , Valor Preditivo dos Testes , Análise de Regressão , Sons Respiratórios/fisiopatologia , Risco , África do Sul/epidemiologiaRESUMO
BACKGROUND AND OBJECTIVE: Selecting 'healthy' preschool-aged children for reference ranges may not be straightforward. Relaxing inclusion criteria for normative data does not affect spirometry z-scores. We therefore investigated the effect of similarly relaxing inclusion criteria in preschoolers on reference ranges for respiratory impedance (Zrs) using a modified forced oscillation technique (FOT). METHODS: The International Study of Asthma and Allergies in Childhood questionnaire classified 585 children into a healthy and five mutually exclusive groups. Zrs was measured between 4 and 26 Hz and resistance (R) and compliance (C) obtained by model fitting. Prediction models were determined using mixed effect models and z-scores compared between healthy children and the five groups. RESULTS: Zrs data were obtained for 494 participants (4.30 ± 0.7 years) on 587 occasions. Comparison of the Zrs z-scores between the healthy children and the health groups found significant differences in children with asthma, current wheeze and respiratory symptoms, but not in children born preterm or with early-life wheeze. Adding these two groups to the healthy dataset had no significant effect on the distribution of z-scores and increased the size of the dataset by 22.3%. CONCLUSION: Our data suggest that preschool-aged children born preterm or with early-life wheeze can be included in FOT reference equations, while those with asthma, current wheeze and respiratory symptoms within 4 weeks of testing should be excluded. This more inclusive approach results in more robust FOT reference ranges.
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Resistência das Vias Respiratórias , Asma/fisiopatologia , Complacência Pulmonar , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Nascimento Prematuro/fisiopatologia , Valores de Referência , Sons Respiratórios , EspirometriaRESUMO
Tracking of the within-breath changes of respiratory mechanics using the forced oscillation technique may provide outcomes that characterise the dynamic behaviour of the airways during normal breathing.We measured respiratory resistance (Rrs) and reactance (Xrs) at 8â Hz in 55 chronic obstructive pulmonary disease (COPD) patients and 20 healthy controls, and evaluated Rrs and Xrs as functions of gas flow (V') and volume (V) during normal breathing cycles. In 12 COPD patients, additional measurements were made at continuous positive airway pressure (CPAP) levels of 4, 8, 14 and 20â hPa.The Rrs and Xrsversus V' and V relationships displayed a variety of loop patterns, allowing characterisation of physiological and pathological processes. The main outcomes emerging from the within-breath analysis were the Xrsversus V loop area (AXV) quantifying expiratory flow limitation, and the tidal change in Xrs during inspiration (ΔXI) reflecting alteration in lung inhomogeneity in COPD. With increasing CPAP, AXV and ΔXI approached the normal ranges, although with a large variability between individuals, whereas mean Rrs remained unchanged.Within-breath tracking of Rrs and Xrs allows an improved assessment of expiratory flow limitation and functional inhomogeneity in COPD; thereby it may help identify the physiological phenotypes of COPD and determine the optimal level of respiratory support.
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Resistência das Vias Respiratórias , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/terapia , Idoso , Estudos de Casos e Controles , Pressão Positiva Contínua nas Vias Aéreas , Impedância Elétrica , Expiração , Feminino , Humanos , Hungria , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Respiração , Testes de Função Respiratória/métodosRESUMO
RATIONALE: Individual assessment of airway obstruction in preschool-age children requires sensitive and specific lung function methods with low demand of cooperation. Although the forced oscillation technique (FOT) is feasible in young children, conventional measurements of respiratory impedance (Zrs) have limited diagnostic power in individuals. OBJECTIVE: To find descriptors of within-breath Zrs that are sensitive indicators of airway obstruction during tidal breathing in children. METHODS: Zrs was measured with (i) a standard multifrequency FOT (4-26â Hz) to assess the mean values of resistance and reactance for whole breaths and (ii) a 10â Hz signal to track the within-breath changes. Various Zrs measures obtained in healthy children (n=75) and those with acute wheeze (n=31) were investigated with receiver operator characteristic (ROC) analysis. The cut-off values obtained for airway obstruction were then tested in children with recurrent wheeze (n=20) before and after administration of salbutamol. RESULTS: The largest area under the ROC curve (0.95) was observed for the tidal changes of resistance between the zero-flow values (ΔR). The ΔR cut-off value of 1.42â hPaâ s/L detected airway obstruction with sensitivity of 92% and specificity of 89% in children with acute wheeze and distinguished children with recurrent wheeze (16/20 above the cut-off value) from healthy children (22/23 below the cut-off value). Furthermore, ΔR significantly decreased after salbutamol in wheezy children but remained unchanged in healthy children. CONCLUSIONS: New lung function measure ΔR is able to detect airway obstruction with high sensitivity and specificity and is suitable for use in lung function testing in young children.
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Resistência das Vias Respiratórias/fisiologia , Pneumopatias Obstrutivas/diagnóstico , Volume de Ventilação Pulmonar/fisiologia , Resistência das Vias Respiratórias/efeitos dos fármacos , Albuterol/farmacologia , Antropometria/métodos , Asma/complicações , Asma/diagnóstico , Asma/fisiopatologia , Broncodilatadores/farmacologia , Criança , Pré-Escolar , Feminino , Humanos , Pneumopatias Obstrutivas/complicações , Pneumopatias Obstrutivas/fisiopatologia , Masculino , Curva ROC , Recidiva , Testes de Função Respiratória/métodos , Sons Respiratórios/etiologia , Sons Respiratórios/fisiopatologia , Sensibilidade e EspecificidadeRESUMO
Introduction: Angiocentric gliomas (AG) in brainstem location are exceedingly rare and might cause differential diagnostic problems and uncertainty regarding the best therapeutic approach. Hereby, we describe the clinicopathological findings in a brainstem AG presenting in a toddler child and review the literature. Case report: A 2-year-old boy presented with 5 weeks history of gait disturbances, frequent falls, left-sided torticollis and swallowing problems. MRI head showed a T2-hyperintense, partly exophytic mass lesion centred in the pontomedullary region, raising the possibility of diffuse midline glioma. The exophytic component was partially resected by suboccipital craniotomy, leaving intact the infiltrative component. Ventriculoperitoneal shunt was implanted due to postoperative hydrocephalus. Histological examination revealed a moderately cellular tumour consisted of bland glial cells infiltrating the brain parenchyma and radially arranged around the blood vessels. By immunohistochemistry, the tumour strongly expressed S100 and GFAP in addition to intense nestin positivity, while OLIG2 was negative in the perivascular tumour cells. DNA methylation array profiled the tumour as "methylation class diffuse astrocytoma, MYB or MYBL1-altered subtype B (infratentorial)" and an in-frame MYB::QKI fusion was identified by RNA sequencing, confirming the diagnosis of angiocentric glioma. The patient has been initially treated with angiogenesis inhibitor and mTOR inhibitor, and now he is receiving palliative vinblastine. He is clinically stable on 9 months follow-up. Conclusion: Brainstem AG may cause a diagnostic problem, and the surgical and oncological management is challenging due to unresectability and lack of response to conventional chemo-radiation. In the future, genetically-tailored therapies might improve the prognosis.
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Astrocitoma , Neoplasias Encefálicas , Glioma , Masculino , Humanos , Pré-Escolar , Neoplasias Encefálicas/diagnóstico , Neoplasias Encefálicas/terapia , Neoplasias Encefálicas/patologia , Glioma/patologia , Astrocitoma/patologia , Tronco Encefálico/patologiaRESUMO
INTRODUCTION: Mechanisms underlying lung dysfunction after preterm birth are poorly understood. Studying phenotypes of prematurity-associated lung disease may aid understanding of underlying mechanisms. Preterm-born children with and without lung dysfunction and term controls were assessed using oscillometry before and after exercise, and after postexercise bronchodilation. METHODS: Preterm-born children, born at gestation of 34 weeks or less, were classified into those with prematurity-associated obstructive lung disease (POLD; FEV1 < LLN, FEV1 /FVC < LLN), prematurity-associated preserved ratio of impaired spirometry (pPRISm; FEV1 < LLN, FEV1 /FVC ≥ LLN) and compared to preterm (FEV1 ≥ LLN) and term controls (%predicted FEV1 > 90%). All children underwent cardiopulmonary exercise, and oscillometry assessment at baseline, postexercise, and after postexercise bronchodilator administration. RESULTS: From 241 participants aged 7-12 years, complete data were available from 179: 15 children with POLD and 11 with pPRISm were compared with 93 preterm and 60 term controls. POLD group, when compared to both control groups, had impaired impedance, greater resistance, more negative (greater magnitude) reactance at low frequencies, and also had decreased compliance. pPRISm group demonstrated impaired reactance and compliance compared to term controls. No differences were noted between the preterm and term controls. Exercise had little impact on oscillometry values, but children with POLD had greatest improvements after postexercise bronchodilator administration, with decreased resistance and decreased magnitude of reactance, particularly at low frequencies. CONCLUSION: Preterm-born children with obstructive airway disease had the greatest oscillometry impairments and the largest improvements after postexercise bronchodilator compared to control groups. Oscillometry can potentially be used to identify preterm-born children with lung disease to institute treatment.
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Doenças do Recém-Nascido , Pneumopatias Obstrutivas , Pneumopatias , Nascimento Prematuro , Criança , Feminino , Humanos , Recém-Nascido , Broncodilatadores/uso terapêutico , Broncodilatadores/farmacologia , Oscilometria , Volume Expiratório Forçado , Pulmão , EspirometriaRESUMO
Background: Oscillometry has been employed widely as a non-invasive and standardized measurement of respiratory function in children and adults; however, limited information is available on infants. Aims: To establish the within-session variability of respiratory impedance (Zrs), to characterize the degree and profile of intra-breath changes in Zrs and to assess their impact on conventional oscillometry in newborns. Methods: 109 healthy newborns were enrolled in the study conducted in the first 5 postpartum days during natural sleep. A custom-made wave-tube oscillometry setup was used, with an 8-48 Hz pseudorandom and a 16 Hz sinusoidal signal used for spectral and intra-breath oscillometry, respectively. A resistance-compliance-inertance (R-C-L) model was fitted to average Zrs spectra obtained from successive 30-s recordings. Intra-breath measures, such as resistance (Rrs) and reactance (Xrs) at the end-expiratory, end-inspiratory and maximum-flow points were estimated from three 90-s recordings. All natural and artifact-free breaths were included in the analysis. Results: Within-session changes in the mean R, C and L values, respectively, were large (mean coefficients of variation: 10.3, 20.3, and 26.6%); the fluctuations of the intra-breath measures were of similar degree (20-24%). Intra-breath analysis also revealed large swings in Rrs and Xrs within the breathing cycle: the peak-to-peak changes amounted to 93% (range: 32-218%) and 41% (9-212%), respectively, of the zero-flow Zrs magnitude. Discussion: Intra-breath tracking of Zrs provides new insight into the determinants of the dynamics of respiratory system, and highlights the biasing effects of mechanical non-linearities on the average Zrs data obtained from the conventional spectral oscillometry.
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Összefoglaló. Bevezetés: A kórboncolás hozzájárul a súlyos akut légzoszervi szindrómát okozó koronavírus-2 (SARS-CoV-2-) fertozés klinikopatológiai vonatkozásainak megismeréséhez. Célkituzés: A SARS-CoV-2-fertozöttek boncolása során gyujtött tapasztalatok bemutatása. Módszer: Egymást követoen boncolt, védooltásban nem részesült, SARS-CoV-2-fertozött elhunytak klinikai adatait, makro- és mikroszkópos észleleteit összegeztük; a tüdokimetszéseket SARS-CoV-2-nukleokapszid-immunfestéssel vizsgáltuk. Eredmények: A boncolást a halálok megállapítására (n = 14), tumorgyanú (n = 9), illetve törvényi kötelezettség (n = 3) miatt végeztük. A fertozést a klinikai észlelés vagy a boncolás során (n = 4) végzett SARS-CoV-2-nukleinsav-teszt igazolta. A tünetes betegség átlagos hossza 12,9 nap volt. 21 betegnél (medián életkor 69 év; 18 férfi) állt fenn COVID-19-pneumonia, mely 16 esetben önmagában, 4 esetben bakteriális pneumoniával vagy álhártyás colitisszel szövodve okozott halált; 1 antikoagulált pneumoniás beteg heveny retroperitonealis vérzésben halt meg. 3 betegnél a halált disszeminálódott malignus tumor, 1 betegnél coronariathrombosis, 1 mentálisan retardált betegnél pedig pulmonalis emboliás szövodmény okozta. A COVID-19-pneumoniás tüdok nehezek, tömöttek és vörösen foltozottak voltak. Szövettanilag a betegség idotartamától függoen diffúz alveolaris károsodás korai exsudativ vagy késobbi proliferativ fázisa látszott atípusos pneumocytákkal; gyakori volt a microthrombosis (n = 7), a macrothrombosis (n = 5), illetve a pulmonalis embolia (n = 4). A SARS-CoV-2-immunfestés pozitívnak bizonyult az esetek 38,5%-ában, dominálóan az exsudativ fázisban. Minden elhunyt társbetegség(ek)ben szenvedett, így magasvérnyomás-betegségben (n = 17), érelmeszesedésben (n = 14), 2-es típusú diabetesben (n = 8), rosszindulatú daganatban (n = 6), krónikus obstruktív tüdobetegségben (n = 4), elhízásban (n = 3), vesetranszplantáció utáni immunszuppresszióban (n = 3). Következtetés: Az irodalmi adatokkal összhangban, halálos COVID-19-pneumonia túlnyomóan idos, társbetegség(ek)tol sújtott férfiakban alakult ki. A boncolási gyakorlatban a SARS-CoV-2-nukleokapszid-immunfestéstol a diffúz alveolaris károsodás korai fázisában várható pozitivitás. Orv Hetil. 2021; 162(45): 1791-1802. INTRODUCTION: Autopsy is an important tool for the evaluation of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Objectice: The aim of this study was to present our experience with autopsies of patients diagnosed with SARS-CoV-2 infection. METHOD: Clinical data, macroscopic and microscopic findings of consecutive postmortems of non-vaccinated SARS-CoV-2 patients are summarized. Lung samples were evaluated with SARS-CoV-2 nucleocapsid immunohistochemistry. RESULTS: Autopsies were performed to determine the cause of death (n = 14), suspected tumours (n = 9) or due to legal obligation (n = 3). SARS-CoV-2 infection was verified by ante mortem (n = 22) and post mortem (n = 4) polymerase chain reaction. The mean duration of symptomatic disease was 12.9 days. Of 21 patients with COVID-19 pneumonia, 16 died of respiratory failure, 4 had additional bacterial pneumonia or Clostridioides difficile infection, and 1 developed hemorrhagic complication (n = 1). Other causes of death included disseminated malignancies (n = 3), coronary thrombosis (n = 1) and pulmonary embolism (n = 1). The affected lungs were heavy and had patchy red appearance. Exudative or proliferative phases of diffuse alveolar damage (DAD) were detected with atypical pneumocytes. Microthrombosis (n = 7), macrothrombosis (n = 5) and pulmonary embolism (n = 4) were frequent. The SARS-CoV-2 immunohistochemical reaction was positive in 38.5% of cases. All patients had co-morbidities, namely, hypertension (n = 17), atherosclerosis (n = 14), diabetes (n = 8), malignancies (n = 6), chronic obstructive pulmonary diseases (n = 4), obesity (n = 3) and immunosuppression after kidney transplantation (n = 3). CONCLUSION: Fatal COVID-19 pneumonia occurred mostly in elderly males with co-morbidities. In the autopsy practice, the SARS-CoV-2 nucleocapsid immunohistochemical reaction may confirm the infectious etiology in the early phase of DAD. Orv Hetil. 2021; 162(45): 1791-1802.
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COVID-19 , Hipertensão , Idoso , Humanos , Masculino , SARS-CoV-2RESUMO
Oscillometric measurements of respiratory system resistance (Rrs) in infants are usually made via the nasal pathways, which not only significantly contribute to overall Rrs but also introduce marked flow (V')-dependent changes. We employed intrabreath oscillometry in casts of the upper airways constructed from head CT images of 46 infants. We examined oscillometric nasal resistance (Rn) in upper airway casts with no respiratory flow (R0) and the effect of varying V' on Rn by simulating tidal breathing. A characteristic nonlinear relationship was found between Rn and V', exhibiting segmental linearity and a prominent breakpoint (V'bp) after log-log transformation. V'bp was linearly related to the preceding value of end-expiratory volume acceleration (Vâ³eE; on average r2 = 0.96, P < 0.001). Rn depended on V', and R at end-expiration (ReE) showed a strong dependence on Vâ³eE in every cast (r2 = 0.994, P < 001) with considerable interindividual variability. The intercept of the linear regression of ReE versus Vâ³eE was found to be a close estimate of R0. These findings were utilized in reanalyzed Rrs data acquired in vivo in a small group of infants (n = 15). Using a graphical method to estimate R0 from ReE, we found a relative contribution of V'-dependent nonlinearity to total resistance of up to 33%. In conclusion, we propose a method for correcting the acceleration-dependent nonlinearity error in ReE. This correction can be adapted to estimate R0 from a single intrabreath oscillometric measurement, which would reduce the masking effects of the upper airways on the changes in the intrathoracic resistance.NEW & NOTEWORTHY Oscillometric measurements of respiratory system resistance (Rrs) in infants are usually made via the nasal pathways, which not only significantly contribute to overall Rrs but also introduce marked flow acceleration-dependent distortions. Here, we propose a method for correcting flow acceleration-dependent nonlinearity error based on in vitro measurements in 3D-printed upper airway casts of infants as well as in vivo measurements. This correction can be adapted to estimate Rrs from a single intrabreath oscillometric measurement.
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Resistência das Vias Respiratórias , Respiração , Humanos , Lactente , Modelos Lineares , Oscilometria , Respiração ArtificialRESUMO
BACKGROUND: Lung function data in healthy newborn infants are scarce largely due to lack of suitable techniques, although data for developmental and prenatal exposure studies are much needed. We have modified the forced oscillation technique (FOT) for the measurement of respiratory mechanical impedance (Zrs) in unsedated sleeping infants in the first 3 days of life. METHODS: Zrs was measured during 30-s epochs of quiet sleep in term neonates born via spontaneous vaginal delivery with a non-invasive FOT between 8 and 48 Hz. Total respiratory resistance (R), compliance (C) and inertance (I) were obtained by fitting Zrs spectra. Cluster analysis was used to determine a set of minimal Zrs spectra representing optimal respiratory mechanics for each infant. RESULTS: Successful measurements were obtained in each of the first 3 days in 30/38 (78.9%) neonates. Group mean (± SD) values of R, C, I, and resonant frequency pooled for the 3 days were 45.9 ± 16.6 hPa s L(-1), 0.97 ± 0.21 ml hPa(-1), 0.082 ± 0.031 hPa s(2) L(-1) and 19.2 ± 3.2 Hz, respectively. Within-session variability represented by coefficient of variation was 5.34 ± 3.18% for R and 13.80 ± 8.57% for C. Greater between-session variability was observed for the individual infants; however, the only statistically significant change over time was a 13% increase in R from day 1 to day 2. Parameter interdependence was significant (r(2) = 0.63) between R and I reflecting the large contribution of the upper airways to the total Zrs. CONCLUSIONS: Noninvasive measurement of Zrs can be made in neonates during natural sleep with a high success rate, even in the first hours of life.