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Avaliação da eficácia do watchpat no diagnóstico da saos : um estudo metodológico
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Abstract(s)
A síndrome de apneia obstrutiva do sono (SAOS) é um distúrbio respiratório que está associada a importantes complicações neurocognitivas e cardiovasculares que podem ser revertidas com o tratamento. O método gold standard para diagnosticar SAOS é a polissonografia (PSG), no entanto este método não se encontra acessível em todos os laboratórios, é limitado pelo seu custo de execução e tempos de espera para a realização do exame. O WatchPAT (WP) é um teste de diagnóstico domiciliário de apneia do sono baseado na tecnologia de tonometria arterial periférica (PAT) e um método relativamente novo para estudar a apneia do sono. Esta tecnologia foi validada por vários estudos para diagnóstico de SAOS, contudo nenhum desses estudos foi realizado na população portuguesa.
Os objetivos deste estudo foram: verificar a validade do equipamento WP 300 comparativamente à PSG nível 1 e avaliar a correlação entre as variáveis medidas por um aparelho portátil para estudo do sono (WP 300) e os medidos pelo método gold standard (PSG) na população portuguesa.
Para tal realizou-se um estudo observacional, transversal, numa amostra consecutiva de doentes referenciado para a realização de PSG, nos quais foi realizado, simultaneamente, estudo do sono com o WP. Foram incluídos 46 participantes (56.5% do género masculino; idade média 53.78 ± 11.3 anos; índice de massa corporal (IMC) 29.0 ± 4.3 Kg/m2).
Da análise comparativa dos parâmetros obtidos, realça-se a sobrestimação pelo WP dos valores médios do tempo total do sono (TTS), índice de apneia e hipopneia (IAH) e saturação média de O2, com diferenças estatisticamente significativas relativamente aos resultados obtidos pela PSG (p<.05), ainda que estas variáveis tenham apresentado boas correlações. Quanto ao diagnóstico de SAOS determinado pelo WP para um limiar de dessaturação de 3%, observou-se uma concordância baixa entre os dois métodos (k=.338), obtendo-se uma sensibilidade de 91%, uma especificidade de 40%, um valor preditivo positivo de 76%, um valor preditivo negativo de 67% e uma exatidão de 74%. Contudo, os dois métodos apresentaram uma boa concordância (k=.615), para um limiar de 4%. Quanto aos diferentes níveis de gravidade do IAH obtidos pelos testes com o WP no limiar de dessaturação de 3%, a concordância foi melhorando progressivamente em função da gravidade da SAOS, sendo bem ilustrada no crescimento dos coeficientes K, passando de .048 na classe ligeira para .934 na classificação grave.
O desempenho diagnóstico demonstrado pelo WP indica de forma clara que este método não poderá substituir, em circunstância alguma, a PSG. Nos casos de ausência de SAOS ou SAOS ligeira diagnosticados pelo WP, é recomendado que seja repetido o exame por uma PSG. Consideramos, assim, que o WP não é um método de diagnóstico de SAOS alternativo ou adjuvante para a PSG, embora se reconheça a sua utilidade como método de rastreio em casos selecionados.
Obstructive sleep apnea syndrome is a respiratory disorder that is associated with significant neurocognitive and cardiovascular complications that can be reversed with treatment. Polysomnography (PSG) is the gold standard method for the diagnosis of obstructive sleep apnea syndrome. However, this method is not available in all laboratories and is limited by its cost and the waiting times for the test to be performed. WatchPAT (WP) is a home diagnostic test for sleep apnea based on peripheral arterial tonometry (PAT) technology and is a relatively new method for studying sleep apnea. This technology has been validated for the diagnosis of obstructive sleep apnea syndrome by several studies, however, none of these studies have been performed in a portuguese population. The objectives of this study were: to verify the validity of the WP 300 equipment compared to PSG level 1 and to evaluate the correlation between the variables measured by a portable sleep study device (WP 300) and those measured by the gold standard method (PSG) in a portuguese population. Therefore an observational, cross-sectional study was carried out in a consecutive sample of patients referred for PSG, in whom a sleep study was simultaneously performed with the WP. A total of 46 participants were included (56.5% male; mean age 53.78 ± 11.3 years; body mass index (BMI) 29.0 ± 4.3 kg/m2). From the comparative analysis of the obtained parameters, it is worth to highlight the overestimation by WP of the mean values of total sleep time, apnea-hypopnea index (AHI) and mean oxygen saturation, with statistically significant differences in relation to the results obtained by PSG (p<.05), although these variables presented good correlations. Regarding the diagnosis of OSAS determined by WP using a 3% desaturation threshold, a low agreement was observed between the two methods (k=.338), obtaining a sensitivity of 91 %, a specificity of 40%, a positive predictive value of 76%, a negative predictive value of 67% and an accuracy of 74%. However, the two methods presented a good agreement (k=.615) when using a 4% threshold. Regarding the different levels of severity of the AHI obtained by the WP using the 3% desaturation threshold, the agreement progressively improved in function of the severity of obstructive sleep apnea syndrome, being well illustrated with the growth of the K coefficients, going from .048 in the mild classification to .934 in the severe classification. The diagnostic performance demonstrated by WP clearly indicates that this method can not replace PSG under any circumstances. In cases of absence of obstructive sleep apnea syndrome or mild obstructive sleep apnea syndrome diagnosed by WP, it is recommended to repeat the examination using PSG. We therefore consider that WP is not an alternative or adjuvant method for the diagnosis of obstructive sleep apnea syndrome, although we recognised its usefulness as a screening method in selected cases.
Obstructive sleep apnea syndrome is a respiratory disorder that is associated with significant neurocognitive and cardiovascular complications that can be reversed with treatment. Polysomnography (PSG) is the gold standard method for the diagnosis of obstructive sleep apnea syndrome. However, this method is not available in all laboratories and is limited by its cost and the waiting times for the test to be performed. WatchPAT (WP) is a home diagnostic test for sleep apnea based on peripheral arterial tonometry (PAT) technology and is a relatively new method for studying sleep apnea. This technology has been validated for the diagnosis of obstructive sleep apnea syndrome by several studies, however, none of these studies have been performed in a portuguese population. The objectives of this study were: to verify the validity of the WP 300 equipment compared to PSG level 1 and to evaluate the correlation between the variables measured by a portable sleep study device (WP 300) and those measured by the gold standard method (PSG) in a portuguese population. Therefore an observational, cross-sectional study was carried out in a consecutive sample of patients referred for PSG, in whom a sleep study was simultaneously performed with the WP. A total of 46 participants were included (56.5% male; mean age 53.78 ± 11.3 years; body mass index (BMI) 29.0 ± 4.3 kg/m2). From the comparative analysis of the obtained parameters, it is worth to highlight the overestimation by WP of the mean values of total sleep time, apnea-hypopnea index (AHI) and mean oxygen saturation, with statistically significant differences in relation to the results obtained by PSG (p<.05), although these variables presented good correlations. Regarding the diagnosis of OSAS determined by WP using a 3% desaturation threshold, a low agreement was observed between the two methods (k=.338), obtaining a sensitivity of 91 %, a specificity of 40%, a positive predictive value of 76%, a negative predictive value of 67% and an accuracy of 74%. However, the two methods presented a good agreement (k=.615) when using a 4% threshold. Regarding the different levels of severity of the AHI obtained by the WP using the 3% desaturation threshold, the agreement progressively improved in function of the severity of obstructive sleep apnea syndrome, being well illustrated with the growth of the K coefficients, going from .048 in the mild classification to .934 in the severe classification. The diagnostic performance demonstrated by WP clearly indicates that this method can not replace PSG under any circumstances. In cases of absence of obstructive sleep apnea syndrome or mild obstructive sleep apnea syndrome diagnosed by WP, it is recommended to repeat the examination using PSG. We therefore consider that WP is not an alternative or adjuvant method for the diagnosis of obstructive sleep apnea syndrome, although we recognised its usefulness as a screening method in selected cases.
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Keywords
Polissonografia Síndrome de Apneia do Sono Tonometria Arterial Periférica WatchPAT Polysomnography Sleep Apnea Syndrome Peripheral Arterial Tonometry WatchPAT