Emilia Sforza

Time-dependent variation in cerebral and autonomic activity during periodic leg movements in sleep: implications for arousal mechanisms

OBJECTIVESnA hierarchy in arousal response has been proposed for spontaneous arousal by analyzing the temporal changes in heart rate (HR) and electroencephalographic (EEG) activity. To address the question as to whether the same continuum may be proposed in sleep disorders, we performed temporal spectral EEG and HR analyses during periodic leg movements (PLM) associated or not with microarousal (MA).nnnMETHODSnData were obtained in 12 patients with restless leg syndrome and/or PLM syndrome. PLMs were classified into 3 types including PLM associated with MA, PLM without MA, and PLM associated with delta or K-complex bursts. HR and EEG spectral analyses were done for 10s before and 10s after the PLM onset.nnnRESULTSnEach type of PLM was associated with a typical EEG and autonomic pattern consisting of an increase in HR and delta band activity before the PLM, regardless of the presence or absence of MA. Thereafter, a rise in delta, alpha and beta(2) activity was noted associated with tachycardia. This was greater when MA or bursts of slow wave activity were present. In the period following the PLM, HR, delta and alpha power showed a long-lasting decrease with values significantly below the baseline.nnnCONCLUSIONSnFrom these data, we can conclude that: (1) cardiac and cerebral changes occur in association with PLM even when MA cannot be detected; (2) the combined increase in delta activity and HR before the onset of PLM suggests that these changes are part of the arousal response during PLM; (3) the graded arousal response during PLM confirms that the human arousal response involves a progression of central nervous system activation from brainstem to cortical level.

Personality, anxiety and mood traits in patients with sleep-related breathing disorders: effect of reduced daytime alertness

OBJECTIVEnThe etiology of depression and personality disorders in patients with sleep-disordered breathing (SDB) is not well defined and it is still unclear if they are directly related to the severity of the disease. In this study we test the hypothesis as to whether daytime sleepiness largely contributes to appearance of mood disorders.nnnMETHODSnSixty patients diagnosed as having snoring (n=16) or OSA (n=44) were examined. Daytime sleepiness was assessed by the administration of the Epworth Sleepiness Scale (ESS) and by the Maintenance Wakefulness Test (MWT). The Hospital Anxiety (HAD-A) and Depression (HAD-D) Scale and the Temperament and Character Inventory (TCI) questionnaires were used for psychopathological evaluation.nnnRESULTSnThe mean HAD-A score was 6.9+/-0.45 and the average HAD-D score was 4.6+/-0.48, with no significant difference between snorers and OSA patients. Anxiety was present in 16% of cases and depression in 7%. The HAD-D score was related to the ESS score (R=0.37, P=0.003), the mean sleep latency at the MWT (R=-0.34, P=0.04), and the mean low SaO(2), ESS score alone explaining the 17% of variance in the HAD-D score. Compared to controls, there were no differences in almost all TCI scores, with novelty-seeking temperament score higher in patients. No relationships were found between HAD or TCI scores and apnea density.nnnCONCLUSIONSnWe conclude that among patients evaluated for SDB, higher depression scores show an association with reduced daytime alertness, which therefore may have important effects on mood.

Determinants of altered quality of life in patients with sleep-related breathing disorders

Recent reports have suggested that altered quality of life and well-being are reported by patients with sleep-related breathing disorders (SRBD). There seems to be no data available in the literature on factors underlying these behavioural consequences. In this study, health-related quality of life (HRQL) scores were examined in SRBD patients in order to establish which factors are implicated in these disturbances. The study group consisted of 130 patients: 49 snorers and 81 patients with obstructive sleep apnoea. The Medical Outcome Survey Short Form-36 questionnaire was administered the morning after the sleep study and scores for the eight dimension scores were obtained. Patients data were compared to normative sex- and age-matched data. In comparison with normal values, scores for all HRQL dimensions were decreased in SRBD patients, with a greater impact on subscores for “vitality”, “physical role”, “social functioning”, “mental health” and “role emotional” dimensions. While impairment in physical function was mostly influenced by sleep stage and obesity, subjective daytime sleepiness mainly affected the other dimensions. The authors conclude that the altered health-related quality of life of sleep-related breathing disorder patients is a multifactorial phenomenon depending on the interaction of sleep stages, daytime sleepiness and obesity, with no significant contribution of sleep fragmentation, hypoxaemia and apnoea recurrence.

Simplified diagnostic procedure for obstructive sleep apnoea syndrome: lower subsequent compliance with CPAP

The aim of this study was to investigate whether a simplified diagnostic procedure based on ambulatory monitoring with MESAM IV altered subsequent compliance with continuous positive airway pressure (CPAP) in obstructive sleep apnoea (OSA) patients. During a period of 16 months, 60 patients with symptoms evocative of OSA and positive MESAM recording were prescribed CPAP after titration with standard polysomnography. Compliance was followed during 2 yrs based on built-in time counters and was compared with the compliance in two comparison groups: an equal number of equally severely affected patients diagnosed with standard polysomnography during the 18 months (8 months before and 8 months after) preceding and following the study period and a group of 48 patients with an estimated similar apnoea/hypopnoea index but less typical clinical and/or MESAM features, diagnosed as having OSA based on polysomnography during the study period. The three groups were not different by age, body mass index, or sleepiness score. Patients diagnosed with the ambulatory procedure had higher drop-out rates (21.7% versus 10% and 6.25%; p<0.05) and lower rates of use of their CPAP (43+/-0.3 h x night(-1)) than any of the control groups (53+/-0.2 and 5.6+/-0.2 h x night(-1), p<0.05). In conclusion, there is a risk that ambulatory diagnostic procedures alter the relationship of patients to their disease and/or the medical staff so that subsequent compliance with treatment may be decreased. The greatest care concerning compliance should be taken before an ambulatory-based diagnostic procedure is implemented.

Performance vigilance task and sleepiness in patients with sleep-disordered breathing

Altered vigilance performance has been documented in patients with sleep-related breathing disorders (SRBDs). Sleep fragmentation, sleepiness, respiratory disturbances and nocturnal hypoxaemia have been suggested as the pathogenesis of these deficits, yet it remains difficult to find a good correlation between performance deficits and the above factors. In the present study, which performance measure better characterised SRBD patients and the main factors implicated in these disturbances were examined. The study group consisted of 152 patients and 45 controls, all examined using a performance vigilance task and subjective sleepiness assessment. Speed and accuracy in the psychomotor vigilance task (PVT) were measured in patients and controls. Objective daytime sleepiness was assessed in the patient group using the maintenance of wakefulness test. In comparison with controls, PVT accuracy rather than speed seems to be affected in SRBD patients, with lapses and false responses significantly greater in patients with more severe objective sleepiness and higher apnoea/hypopnoea index. Although slowing and increased variability in reaction time were associated with shorter sleep latency in the maintenance of wakefulness test, subjective sleepiness, sleep fragmentation, nocturnal hypoxaemia and apnoea/hypopnoea index influenced mainly PVT accuracy. It is concluded that vigilance impairment, sleep fragmentation and severity of disease may partially and differentially contribute to the diurnal performance consequences found in sleep-related breathing disorders. Since the psychomotor vigilance task worsening is more marked in accuracy that in speed, measurement of lapses and false responses would better characterise the degree of diurnal impairment in these patients.

Nocturnal Pollakiuria Is a Symptom of Obstructive Sleep Apnea

An increased urine excretion has been reported in obstructive sleep apnea (OSA) patients, but it is not clear whether it results in an increased number of nocturnal micturitions. The present study was aimed at investigating the frequency of nocturnal micturitions in OSA patients using a standardized questionnaire prospectively given to 102 OSA patients and 86 healthy male subjects. The frequency of nocturnal micturitions was significantly greater in the OSA patients than in the healthy subjects (more than 70% of the OSA patients with an apnea+hypopnea index > 50 reported nocturnal micturitions more than twice a week versus less than 25% of the healthy subjects, p < 0.0001). The number of nocturnal micturitions was also greater in the OSA patients than in the healthy subjects. There was an effect of age on the frequency of nocturnal micturitions; however, when age-matched subsamples were considered, there was still a significant difference between OSA patients and healthy subjects. In a subgroup of 25 OSA patients reevaluated after at least 1 year of home treatment with nasal continuous positive airway pressure the reported frequency of nocturnal micturitions had significantly decreased (p < 0.001). These results suggest that investigations aimed at establishing a diagnosis of OSA should be part of the work-up of patients complaining of nocturnal pollakiuria.

Nocturnal evolution of respiratory effort in obstructive sleep apnoea syndrome: influence on arousal threshold.

It has been recently described that the overnight increase in maximal end-apnoeic oesophageal pressure (P(oes,max)), considered as an index of the arousal threshold to occlusion, mostly contributes to apnoea lengthening during the night. However, the rise in apnoea duration could also be caused by changes in hypoxaemia, chemosensitivity and upper airway resistance. To better define the relative contributions of each of these factors, we examined the recordings of nine patients. Before apnoea, the mean pulmonary resistance at peak inspiratory flow (RPIF) was computed. During apnoea, all swings in oesophageal pressure (P(oes)) were measured to define the P(oes,max), the increase from the minimum to the maximum (deltaP(oes)), the rate of increase in P(oes) (RP(oes)) and the P(oes) at the first occluded breath (P(oes,1)). A gradual and significant increase in apnoea duration (p=0.02), P(oes,max) (p=0.02) and deltaP(oes) (p=0.006) was present across the night without any changes in oxygen saturation, RPIF, and P(oes,1). The slope of increase in P(oes,max), apnoea duration and deltaP(oes) was correlated with the apnoea/hypopnoea index. We conclude that in obstructive sleep apnoea, the nocturnal rise in apnoea duration is attributable more to an increase in the arousal threshold related to apnoea recurrence than to changes in chemosensitivity and upper airway resistance.

URINARY EXCRETION OF PROSTANOIDS DURING SLEEP IN OBSTRUCTIVE SLEEP APNOEA PATIENTS

1. Given the unexplained frequent association between systemic hypertension and obstructive sleep apnoea (OSA), the secretion of prostanoids during sleep was investigated (more specifically, the ratio of prostacyclin (PGI2) to thromboxane A2 (TxA2), since they have marked opposite effects on vascular tone). Prostacyclin has vasodilating effects, whereas thromboxane results in vasoconstriction.