Domiciliary Diagnosis and Follow up in Obstructive Apnoea Syndrome

The aim of our study was to evaluate the effectiveness of a home programme (diagnosis and follow-up) in patients with Obstructive Sleep Apnea (OSA) syndrome treated with CPAP and to analyze the cost of this approach.

Detailed Description: We conducted a prospective comparative study. Patients referred for suspected OSAS were evaluated. In the first visit patients completed four questionnaires: Epworth sleepiness scale, Impact Functional Illness Questionnaire (FOSQ), activity questionnaire and symptom questionnaire.

Patients were randomised to three groups:

• Group A (domiciliary group): home based diagnosis by home respiratory polygraphy (RP) and home review conducted by a specialist nurse
• Group B (Hospital group): hospital based diagnosis by polysomnography (PSG) and clinical review conducted by a Pulmonologist
• Group C (mixed group): home based diagnosis by home respiratory polygraphy (RP) and clinical review conducted by a Pulmonologist

Following the diagnostic test (PSG or RP), patients were visited by the Pulmonologist, who identified the need for CPAP treatment.

Patients were evaluated after 1,3 and 6 months of CPAP treatment. In all follow-up visits compliance was evaluated by objective methods and questionnaires described above were filled in.

In domiciliary group, phone calls or hospital appointments were made if low compliance was detected or if some problem with treatment was detected.

Instrumentation.

• Conventional PSG was performed in hospital supervised by a trained nurse. PSG used for the study was Somnostar alfa®. Parameters obtained were: electroencephalogram (C3-A2, C4-A1), electrooculogram electromyogram, electrocardiogram (V2 modified), respiratory effort by thoracic and abdominal resistance bands, air flow with nasal cannula pressure connected to a transducer, oxygen saturation with a pulseoximeter, and snoring with a selective microphone. PSG was manually interpreted in 30 seconds epochs, according to Rechschaffen and Kales criteria.The apnea-hypopnea index (AHI) was defined as the number of apneas-hypopneas divided by the number of hours of sleep. OSA diagnosis was done if AHI was >10 /h.
• Respiratory polygraphy was performed in a non-attended way in patient's home. The nurse who monitorized the patient in the home setting, instructed the patient on the proper use of the RP. A validated respiratory polygraphy system corresponding to ASDA level III (Stardust®) was used. The parameters monitorized were: nasal flow, chest movement, oxyhemoglobin saturation, pulse and body position. The same cardio-respiratory variables that we identified in PSG, were registered. An event rate (number of apneas + number of hypopnea divided by the number of hours recorded)> 15 was considered as a diagnosis. The study were recorded by computer system and manually interpreted by a physician. In case of invalid registration we performed a second PR. If in doubt after the second study a PSG was performed.

Follow-up visits and assessment of compliance:

• Hospital monitoring group: Effective compliance was calculated by mean of the CPAP hour meter, dividing the total number of hours timer by the number of days of use. We discounted 10% of the time, which is the average time of ineffective pressure. Patients were considered adherent if they use CPAP at least 4 hours during 70% of the week
• Follow-up visits by nurses: This group of patients was treated at home through a system of fixed pressure CPAP (REMstar Pro, Respironics ®), with a memory card which can store information about the number of hours of effective pressure. It also allows to know the number of days of CPAP use. In all visits the nurse collect the memory card for later analysis, which was performed by a physician.The nurse responsible for the program evaluated the need of reinforcing in order to get an optimal compliance. If it was considered necessary, the patient was evaluated by the Pulmonologist either by mean of a phone call or of an hospital appointment. All patients in this group were contacted by phone at least once during the first month of CPAP treatment