2003, Number 6
Evaluación de la memoria a corto plazo en pacientes con apnea del sueño antes y después del tratamiento con CPAP
Sánchez AI, Bermúdez MP, Buela-Casal G
Full text
Language: Spanish
References: 28
Page: 55-61
PDF size: 204.54 Kb.
ABSTRACT
Obstructive Sleep Apnea Syndrome (OSAS) is a disorder characterized by an obstruction in the upper respiratory airway during sleep. This obstruction provokes a series of complete respiratory pauses (apneas) or partial respiratory pauses (hypopnea) of a duration surpassing 10 seconds, along with a reduction in the arterial oxygen saturation. During sleep, the presence of awakenings, loud snoring, as well as a loss or suppression of the most profound sleep phases (phases III and IV of NREM sleep and REM phase) take place. During the day, the patient exhibits a very varied range of symptoms which affects his daytime functioning. Specifically, the most significant symptoms are excessive daily somnolence, changes in mood and cognitive functioning, fatigue, irritability, cephaleas, etc. It is estimated that OSAS affects 2-4% of the general adult population. It mainly affects middle-aged males. A very high percentage of patients are obese, snorers, as well as habitual consumers of alcohol, tobacco and hypnotic sedatives before sleep, etc.OSAS is one of the disorders which most deteriorates the cognitive execution of patients, where deficits in short term memory, verbal training, perception, thinking and communication are observed, as well as a deficit in the so-called executive functions, and in this process a significant decrease in the ability to initiate new mental processes, a tendency to commit persistent errors and a deterioration in cognitive processes of planification and execution are the main symptoms observed. It has been considered that the possible factors responsible for these cognitive deficits are both, the lack of oxygen during sleep and excessive daytime somnolence.
Nowadays, Continuous Positive Airway Pressure: CPAP is the treatment most used for this sleep disorder. The functioning of CPAP consists in administering a continuous air flow, higher than the environmental pressure, on the upper respiratory airway, by means of a nasal mask. This pressure avoids obstruction of the upper respiratory airway, which allows patients to sleep without experiencing sleep interruptions. The level of pressure necessary to achieve this objective must be determined individually for each patient during the nocturnal sleep recording.
Diverse studies have evaluated the efficacy of treatment in the symptomology of OSAS, although the results are not conclusive; in other words, cases have been identified in which patients have improved significantly in some cognitive functions, whilst in others, these improvements were not observed in spite of the decrease found in levels of daytime somnolence. Therefore, in this study, and in regard to the results of previously analysed studies, the objective was to evaluate the effects of CPAP on the short term memory of patients with OSAS after a month of treatment.
Material and method
The sample was made up of 44 patients (42 men and 2 women) with OSAS, who were chosen from a hospital center. The diagnostic criteria used for the selection of these patients was that they presented an index of apnea-hypopnea›10. The age range varied between 30 and 65 (X= 47.84 and DT= 8.15). In all the patients CPAP was used as an alternative therapy. The obstructive apneas are defined as the cessation of air flow during sleep accompanied by respiratory movements with duration of over 10 seconds. The hypopnea was defined as an episode in which partial obstruction of the upper respiratory airways resulted in a significant decrease in air flow.
In order to establish a diagnosis of OSAS, a cardio-respiratory polygraph was taken during all the sleeping hours for each one of the patients. This diagnostic technique, which is simpler than the polysomnograph, has made possible in the last few years, to diagnose this disorder and/or treat a greater number of patients. The procedure includes an electrocardiogram and recordings of thoracic and abdominal movements, air flow through the nose and mouth and the level of oxygen saturation in the blood. The patients chose presented ratios of somnolence pathologies according to Epworth’s Somnolence Scale. The test of WAIS digits in direct and inverse order was used to evaluate short term memory.
For treatment of the disorder, the systems CPAP Nasal SULLIVAN and the System CPAP PV 100 were used. Both have an apparatus that generates air, a mask, an air tube to connect the generator to the mask, an adjustable frame to hold the mask onto the head and a pad for the nose. The pressures used, oscillated between 5 and 12 cms H20.
Before the sleep recording, a medical examination and interview was carried out for each patient with the objective of obtaining any data of special relevance for the disorder diagnosis. E.g. most frequent symptoms, family and personal history, consumption of alcohol and tobacco, approximate period of time in which the symptoms began to appear, etc. During this first interview, the information provided by relatives (especially the partner) about the symptoms shown by the patient, was assessed. Once the examination was completed, the patient was given an appointment to sleep in the sleep unit, that same night, in which the first cardio-respiratory polygraph would be taken. The recording began at 11.30 p.m. approximately and finalized at 7.30 a.m. with a recording of 6 hours of sleep.
The following morning the sleep recording was analyzed to determine if the patient did or did not show obstructive sleep apnea, and the degree of the disorder. The parameters analyzed were as follows: a) Total obstructive apneas, minimum and maximum duration and index of apneas; b) Total hypopneas, minimum and maximum duration and index of hypopneas; c) De-saturation throughout the night and average fall; d) Average and minimum level of SAO2%, and e)Index of apneas-hypopneas. Once the analysis was complited, the selected subjects for the study were those patients who presented an apnea-hypopnea index higher than 10 and those who had established the CPAP as alternative therapy. In addition to the data obtained in the polygraph, the information which the patient himself and his family provided about the symptoms the patient exhibited, were also assessed.
Once the diagnosis was concluded, psychological evaluation tests were carried out in the same place and under the same conditions for each subject. Its application was individual. Within the experimental procedures, the following variables were controlled: age, environmental variables (light, noise, temperature), food ingested, the time of day at which the evaluation was made, consumption of alcohol or tobacco, etc. Once this phase was concluded, an appointment was made for the patient to sleep for a second night in the sleep unit to carry out an adaptation to the CPAP. All the patients were given an appointment at approximately one month after the CPAP therapy had begun, in which a new evaluation of short term memory was made. During the follow-up period a specialized team evaluated the compliance of treatment which involved a further 5.51 hours of treatment per month.
In order to analyse these data, a quasi-experimental multivaried design of repeated measurements was made which allowed us to verify if there existed a main effect of the treatment factor with CPAP.
Results
The results of the variance analysis indicate statistical significant differences in short term memory after a month of treatment (p‹0.05), and to be specific, an increment in the number of digits recorded with reference to the base situation was observed.
Conclusions
The previous results show that the CPAP improves the cognitive functioning of the patients with OSAS, incrementing the number of digits recorded in a short term memory task, which may be due, amongst other reasons, to an improvement in the level of daytime somnolence or rather, to a significant improvement in the levels of oxygen saturation (SaO2).
REFERENCES