Diagnostic performance of nocturnal oximetry in the detection of obstructive sleep apnea syndrome: a Brazilian study.

OBJECTIVE: Due to the increasing prevalence of obstructive sleep apnea (OSA), more practical diagnostic methods than polysomnography (PSG) have become necessary. This research aims to analyze the performance of nocturnal oximetry (NO) in the diagnosis of OSA. METHODS: In this cross-sectional study, we analyzed 41 variables provided by the oximetry of all PSG performed by the LabSono of University Hospital Gaffrée and Guinle, a total of 83 exams. We evaluated the correlation coefficients (Spearman) between these data and the Apnea/Hypopnea Index (AHI) and then calculated the diagnostics performances, by the area under the curve (ROC) (AUC), of the best correlated variables and their respective cutoffs, in the identification of an AHI ≥ 15/h. RESULTS: Virtually all oximetric data showed good correlations with AHI, except for some temporal data. We chose 5 of them and calculated their diagnostic performances. T < 90% shows AUC of 0.904 (0.835-0.972) and, at cutoff > 19 min, a sensitivity (Sens.) of 75.68% and specificity (Spec.) of 95.65%. DO3/10Total, AUC 0.936 (0.888-0.989), and at the cutoff > 51 has Sens. 97.3% and Spec. 76.09%. ODI3/10/h has AUC 0.932 (0.884-0.988), at the cutoff > 7/h, Sens. 97.3% and Spec. 78.26%. DO4/5Total AUC 0.932 (0.882-0.981), at the cutoff > 64 has Sens. 86.49% and Spec. 82.61% and ODI4/5/h has AUC 0.930 (0.880-0.981), the cutoff > 5.69/h Sens. 97.3% and Spec. 73.91%. CONCLUSIONS: Our study concludes that NO is accurate in identifying AHI > 15/h, and provides reliable information on PSG replacement, which could make the diagnosis of OSA cheaper and more comfortable.

Is phrenic nerve conduction affected in patients with difficult-to-treat asthma?

Objective The aim of this study was to obtain data on phrenic neuroconduction and electromyography of the diaphragm muscle in difficult-to-treat asthmatic patients and compare the results to those obtained in controls. Methods The study consisted of 20 difficult-to-treat asthmatic patients compared with 27 controls. Spirometry, maximal inspiratory and expiratory pressure, chest X-ray, phrenic neuroconduction and diaphragm electromyography data were obtained. Results The phrenic compound motor action potential area was reduced, compared with controls, and all the patients had normal diaphragm electromyography. Conclusion It is possible that a reduced phrenic compound motor action potential area, without electromyography abnormalities, could be related to diaphragm muscle fiber abnormalities due to overload activity.

Phrenic nerve conduction studies: normative data and technical aspects.

OBJECTIVE: The aim of the present study was to define normative data of phrenic nerve conduction parameters of a healthy population. METHODS: Phrenic nerve conduction studies were performed in 27 healthy volunteers. RESULTS: The normative limits for expiratory phrenic nerve compound muscle action potential were: amplitude (0.47 mv - 0.83 mv), latency (5.74 ms - 7.10 ms), area (6.20 ms/mv - 7.20 ms/mv) and duration (18.30 ms - 20.96 ms). Inspiratory normative limits were: amplitude (0.67 mv - 1.11 mv), latency (5.90 ms - 6.34 ms), area (5.62 ms/mv - 6.72 ms/mv) and duration (13.77 ms - 15.37 ms). CONCLUSION: The best point of phrenic nerve stimulus in the neck varies among individuals between the medial and lateral border of the clavicular head of the sternocleidomastoid muscle and stimulation of both sites, then choosing the best phrenic nerve response, seems to be the appropriate procedure.

Is phrenic nerve conduction affected in patients with difficult-to-treat asthma? / A neurocondução do nervo frênico está alterada na asma de difícil controle?

ABSTRACT Objective The aim of this study was to obtain data on phrenic neuroconduction and electromyography of the diaphragm muscle in difficult-to-treat asthmatic patients and compare the results to those obtained in controls. Methods The study consisted of 20 difficult-to-treat asthmatic patients compared with 27 controls. Spirometry, maximal inspiratory and expiratory pressure, chest X-ray, phrenic neuroconduction and diaphragm electromyography data were obtained. Results The phrenic compound motor action potential area was reduced, compared with controls, and all the patients had normal diaphragm electromyography. Conclusion It is possible that a reduced phrenic compound motor action potential area, without electromyography abnormalities, could be related to diaphragm muscle fiber abnormalities due to overload activity.

RESUMO Objetivo O objetivo do presente estudo foi obter dados da neurocondução do frênico e exame com agulha do diafragma em pacientes com asma de difícil controlee comparar com um grupo normal. Métodos O estudo consiste em realizar radiografia de tórax, espirometria, pressão máxima inspiratória e expiratória, neurocondução do nervo frênico e eletromiografia do músculo diafragma em 20 pacientes asmáticos de difícil controle e comparar com 27 controles. Resultados Encontramos redução da área do potencial de ação muscular composto do nervo frênico e a eletromiografia do musculo diafragma estava normal em todos os pacientes. Conclusão É possível que a redução da área do potencial de ação muscular composto do nervo frênico nos pacientes com asma de difícil controle associado a eletromiografia normal do músculo diafragma esteja relacionada as alterações da fibra muscular do mesmo devido à sobrecarga de atividade.

Phrenic nerve conduction studies: normative data and technical aspects / Aspectos técnicos e normatização da neurocondução do nervo frênico

ABSTRACT Objective: The aim of the present study was to define normative data of phrenic nerve conduction parameters of a healthy population. Methods: Phrenic nerve conduction studies were performed in 27 healthy volunteers. Results: The normative limits for expiratory phrenic nerve compound muscle action potential were: amplitude (0.47 mv - 0.83 mv), latency (5.74 ms - 7.10 ms), area (6.20 ms/mv - 7.20 ms/mv) and duration (18.30 ms - 20.96 ms). Inspiratory normative limits were: amplitude (0.67 mv - 1.11 mv), latency (5.90 ms - 6.34 ms), area (5.62 ms/mv - 6.72 ms/mv) and duration (13.77 ms - 15.37 ms). Conclusion: The best point of phrenic nerve stimulus in the neck varies among individuals between the medial and lateral border of the clavicular head of the sternocleidomastoid muscle and stimulation of both sites, then choosing the best phrenic nerve response, seems to be the appropriate procedure.

RESUMO Objetivo: O objetivo do presente estudo foi definir os dados normativos de condução do nervo frênico de uma população saudável. Métodos: Foram realizados estudos de condução do nervo frênico em 27 voluntários saudáveis. Resultados: Os limites normais do potencial de ação muscular composto do nervo frênico durante a expiração foram: amplitude (0.47 mv - 0.83 mv), latência (5.74 ms - 7.10 ms), área (6.20 ms/mv - 7.20 ms/mv) e duração (18.30 ms - 20.96 ms). E durante a inspiração os limites normais foram: amplitude (0.67 mv - 1.11 mv), latência (5.90 ms - 6.34 ms), área (5.62 ms/mv - 6.72 ms/mv) e duração (13.77 ms - 15.37 ms). Conclusão: O melhor ponto de estímulo do nervo frênico no pescoço varia entre a borda medial e lateral da cabeça clavicular do músculo esternocleidomastóideo. Estimular ambos os locais e escolher a melhor resposta do nervo frênico parece ser o procedimento mais adequado.