Obstructive sleep apnoea syndrome: is the "half-night polysomnography" an adequate method for evaluating sleep profile and respiratory events?

Abstract

Recently, to reduce the costs of polysomnography, split-night studies have been introduced into routine practice: the first part of the night is used to make the diagnosis of obstructive sleep apnoea syndrome (OSAS) and the second part to achieve an appropriate level of continuous positive airway pressure. Since this split-night protocol has not yet been validated by the comparison of polysomnographic pictures obtained in the first and second parts of the night, the aim of this study was to evaluate sleep profile and respiratory disturbances in the first part (PSG1) and second (PSG2) portion of a standard full-night polysomnographic examination (PSGtot) in a group of OSAS patients.Twenty nine consecutive OSAS patients, aged 54±10 yrs; body mass index (BMI) 40±6 kg·m -2 (mean±SD values), were studied by separate analyses of PSG1, PSG2 and PSGtot.PSG1 was found to have a low sensitivity value (66%). A significant difference was found between apnoea-hypopnoea indices (AHI) recorded in PSG1, PSG2 and PSGtot (mean±SD, AHI1 33±27, AHI2 45±28, AHItot 40±25 events·h -1 , respectively; p<0.01). A strong correlation was observed between AHItot and AHI1 (r=0.89) and between AHItot and AHI2 (r=0.92), but a weaker correlation between AHI1 and AHI2 (r=0.66). These correlations became weaker when patients were subdivided into two different classes on the basis of disease severity. PSG1 was representative of PSGtot and similar to PSG2 only in those patients with rapid eye movement (REM) phase sleep in the first part of the night.We conclude that split-night protocols are not appropriate for evaluating sleepdisordered breathing in obstructive sleep apnoea syndrome patients when rapid eye movement phase sleep does not occur in the first part of the night.

Predicting Continuous Positive Airway Pressure from a Modified Split-Night Protocol in Moderate to Severe Obstructive Sleep Apnea-Hypopnea Syndrome

“…In 88% of these reproducible patients, optimal effective CPAP levels were reached despite using stricter indicators for CPAP titration and successful CPAP titration as compared to previous reports (7,9,10,(13)(14)(15)(16)(17) (13)(14)(15). If the subject had low AHI during the diagnostic period, the diagnostic part might be expanded into a fullnight protocol, thereby reducing the false-negative diagnostic rate in the split-night protocol.…”

“…In contrast, in most previous reports on split-night study AHI of 5-40 events/h is an indicator for CPAP titration (9,10,(13)(14)(15)(16)(17) and events/ h is an indicator for successful CPAP titration (7,14,15 (15), since the standard duration of diagnostic split-night study has been suggested to be !2 hours, which might leave the remaining sleep time insufficient for CPAP titration (9,10 …”

“…There might be some concerns on a shortened diagnostic protocol: 1) too little REM sleep is not representative of the 2nd part (13) …”

La polisomnografía en noche dividida es eficaz para titular la presión en la ventilación con presión positiva continua ("CPAP") en pacientes con apnea obstructiva del sueño

“…Esta consiste en realizar una PSG estándar en la primera parte de la noche para realizar el diagnóstico, mientras que la segunda parte se establece la presión necesaria de CPAPn para el tratamiento. Algunos autores rechazan el estudio de PSG en noche dividida, argumentando que por el escaso tiempo de registro, la gravedad del SAHOS sería minimizada y que no sería posible titular adecuadamente a los pacientes 18 .…”

Full polysomnography versus home sleep study: searching for the optimal procedure

“…This has the major disadvantage that it halves the time available for introduction of CPAP, perhaps the most critical moment in management. In addition, the first and second halves of the night are not equivalent [19].…”