Biomedical subjects

Giora Pillar

Publications and source records attributed to Giora Pillar.

26 records · Page 2Linked to original sources

PubMed2003

Long-term intermittent exposure to high ambient CO2 causes respiratory disturbances during sleep in submariners.

BACKGROUND: During most of the cruise, submarines are detached from their environment. Therefore, O(2) levels are relatively low (19 kPa, 144 mm Hg) and CO(2) levels are high (1 kPa, 7.6 mm Hg). There are, however, periods during ventilation of the submarine in which CO(2) levels drop and O(2) levels increase. The objective of this study was to determine whether these unique gas changes might result in sleep-disordered breathing in submariners. METHODS AND MATERIALS: The sleep of eight healthy soldiers was assessed three times: (1) control night, in submarine docking; (2) at the beginning of the cruise (reflecting acute exposure to gas changes); and (3) at the end of the cruise (chronic exposure to gas changes). Each night was divided to three parts because of different CO(2) levels (secondary to ventilation of the submarine). Sleep and breathing were measured using the portable Watch PAT100 device (Itamar Medical, Ltd; Caesarea, Israel) to detect breathing abnormalities during sleep. RESULTS: Sleep and breathing data were categorized according to four CO(2) conditions: acute moderate (inhaled CO(2) levels of 2.3 to 5 mm Hg during first 1 to 2 nights of the cruise); acute high (inhaled CO(2) levels of 5 to 9.2 mm Hg during the first 1 to 2 nights of the cruise); chronic moderate (inhaled CO(2) levels of 2.3 to 5 mm Hg during nights 9 to 10 of the cruise); and chronic high (inhaled CO(2) levels of 5 to 9.2 mm Hg during nights 9 to 10 of the cruise). Respiratory disturbance index (RDI) was significantly higher in the chronic moderate CO(2) condition than the chronic high condition (18.9/h vs 8/h, p < 0.005). RDI did not correlate with CO(2) levels during the first nights of the cruise (R = - 0.2, not significant), but significantly negatively correlated with it during the last nights of the cruise (R = - 0.56, p < 0.05). CONCLUSIONS: We conclude that during an 11-day cruise, submariners adapt to high CO(2) levels, as evidenced by the significant dependence of RDI on CO(2) during the final but not initial days of the cruise. This adaptation resulted in a significant increase in RDI when CO(2) levels declined during the later nights of the cruise.

Adult↗

PubMed2003

Sleep apnoea in the older adult : pathophysiology, epidemiology, consequences and management.

Sleep apnoea is a breathing disorder in sleep usually caused by repetitive upper airway obstruction. Its primary symptoms include snoring, daytime sleepiness and decreased cognitive functioning. Risk factors for the condition include obesity, anatomical abnormalities, aging, and family history. It has been associated with hypertension, cardiovascular and pulmonary diseases and increased mortality. The prevalence of sleep apnoea increases with age, although the severity of the disorder, as well as the morbidity and mortality associated with it, may actually decrease in the elderly. A decline in cognitive functioning in older adults with sleep apnoea may resemble dementia. Medical management of sleep apnoea rarely relies on drug treatment, as the few drugs (antidepressants and respiratory stimulants) tested for treatment have been found to be ineffective, or cause tolerance or serious adverse effects and complications. The treatment of choice for sleep apnoea is continuous positive airway pressure, a device which generates positive air pressure through a nose mask, creating a splint which keeps the airway unobstructed throughout the night. Weight loss significantly decreases or eliminates apnoeas. Oral appliances are used to enlarge the airway at night by moving the tongue and mandible forward. Positional therapy involves avoiding the supine position during sleep in patients who mostly have apnoeas while lying on their back. Surgical management may also be considered, although with great caution in the elderly, because of their increased risk of complications related to surgery. Surgical procedures include nasal reconstruction, somnoplasty, laser-assisted uvuloplasty, uvulopalatopharyngoplasty, genioglossus advancement and hyoid myotomy, and maxillomandibular advancement for severe cases when other treatments have failed. As a last option, tracheostomy may be performed.

Aged↗

PubMed2002

The male predisposition to pharyngeal collapse: importance of airway length.

Obstructive sleep apnea is an important disorder because of both its prevalence and its cardiovascular and neurocognitive sequelae. Despite the fact that male sex is a major risk factor for this disorder, the mechanisms underlying this predisposition are unclear. To understand the pathophysiologic basis of the male predisposition for pharyngeal collapse, we performed a detailed analysis of the anatomic and physiologic features of the upper airway in a cohort of normal and near-normal subjects (equal number of men and women). Although no important physiologic (genioglossal electromyogram, airflow resistance) differences were observed between sexes, a number of anatomic differences were apparent. The pharyngeal airway length was substantially longer in men compared with women. There was also an increased cross-sectional area of the soft palate and an increased airway volume in men compared with women. Using signal-averaged anatomic data from male and female subjects, we developed representative male and female finite element airway models. This model demonstrated the male airway to be substantially more collapsible than the female airway, solely on the basis of anatomic differences. This study suggests that the male predisposition to pharyngeal collapse is anatomically based, primarily as the result of an increased length of vulnerable airway as well as increased soft palate size.

Adult↗

PubMed2002

Autonomic arousal index: an automated detection based on peripheral arterial tonometry.

Arousals from sleep are associated with increased sympathetic activation and are therefore associated with peripheral vasoconstriction. We hypothesized that digital vasoconstrictions as measured by peripheral arterial tonometery (PAT), combined with an increase in pulse rate, would accurately reflect arousals from sleep, and can provide an autonomic arousal index (AAI). Based on a previously studied group of 40 sleep apnea patients simultaneously recorded by both polysomnography (PSG) and PAT systems, an automated algorithm using the PAT signal (and pulse rate derived from it) was developed for detection of arousals from sleep. This was further validated in a separate group of 96 subjects (85 patients referred with suspected obstructive sleep apnea and 11 healthy volunteers mean age 46.2+/-14.4 years, BMI 28.5+/-5.4 kg/m2). All underwent a whole night PSG with simultaneous PAT recording. The PSG recordings were blindly manually analyzed for arousals based on American Academy of Sleep Medicine (AASM) criteria, while PAT was scored automatically. There was a significant correlation between PSG and PAT arousals (R=0.82, p<0.0001) with a good agreement across a wide range of values, with a ROC curve having an area under the curve (AUC) of 0.88. We conclude that automated analysis of the peripheral arterial tonometry signal can detect EEG arousals from sleep, in a relatively quick and reproducible fashion.

Arousal↗

PubMed2002

Pharyngeal pressure and flow effects on genioglossus activation in normal subjects.

Pharyngeal dilator muscles are clearly important in the pathogenesis of obstructive sleep apnea syndrome. Substantial data support the role of local mechanisms in mediating pharyngeal dilator muscle activation in normal humans during wakefulness. Using a recently reported iron lung ventilation model, we sought to determine the stimuli modulating genioglossus activity, dissociating the influences of pharyngeal negative pressure, from inspiratory airflow, resistance, and CO(2). To achieve this aim, we used two gas densities at several levels of end-tidal CO(2) and a number of intrapharyngeal negative pressures. The correlations between genioglossus electromyography (GGEMG) and epiglottic pressure across a breath remained robust under all conditions (R values range from 0.71 +/- 0.07 to 0.83 +/- 0.05). In addition, there was no significant change in the slope of this relationship despite variable gas density or CO(2) levels. Although flow also showed strong correlations with genioglossus activity, there was a significant change in the slope of the GGEMG/flow relationship with altered gas density. For the group averages across conditions (between breath analysis), the correlation with GGEMG was robust for negative pressure (R(2) = 0.98) and less strong for other variables such as flow and resistance. These data suggest that independent of central pattern generator activity, intrapharyngeal negative pressure itself modulates genioglossus activity both within breaths and between breaths.

Adult↗

PubMed2002

DRB11502-DQB10601-DQA10103 and DRB104-DQB1*0302 in Jewish hypersomnolent patients.

OBJECTIVES: Narcolepsy is a sleep disorder with a genetic association with the haplotype DRB1*1501, DQA1*0102, DQB1*0602. This haplotype has been described in different ethnic groups suffering from narcolepsy (Japanese, Caucasian, African Americans, Jews). In a recent study we have found the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in three patients with hypersomnolence. The similarity of this haplotype to the narcoleptic haplotype DRB1*1501, DQB1*0602 and DQA1*0102 has raised the question of whether this haplotype is a marker for sleepiness, or rather indicates a variant of non-cataplectic narcolepsy. This study was conducted to further investigate this question. METHODS: HLA-DNA analysis was carried out in 20 healthy Jewish patients (age 23.9+/-6.3 years; 13 Ashkenazi, seven non-Ashkenazi) who had objective measures of hypersomnolence. All underwent whole-night polysomnography, multiple sleep latency test and tissue typing. RESULTS: HLA-DNA analysis revealed HLA-DR2 in eight patients of whom five (25%) carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103 (vs. 1.4% in the Israeli population, P<0.0001). Six patients were diagnosed as non-cataplectic narcoleptics. Five of them carried the haplotype DRB1*1502, DQB1*0601, DQA1*0103. Forty percent of the patients carried the haplotype DRB1*04, DQB1*0302, which was not statistically different from its prevalence in the healthy Israeli population (25%). CONCLUSIONS: This is the first report describing the haplotype DRB1*1502, DQB1*0601, DQA1*0103 in narcoleptic patients (non-cataplectic). This haplotype is close but different from the already known narcoleptic haplotype DRB1*1501, DQA1*0102, DQB1*0602. We assume that this haplotype represents a variant of non-cataplectic narcolepsy rather than association with hypersomnolence. However, in order to conclude whether this haplotype is a marker for the lack of cataplexy, or represents a variant of non-cataplectic narcolepsy, a larger group of patients should be investigated.

Journal Article↗

PubMed2002

Severe hypersomnolence after pituitary/hypothalamic surgery in adolescents: clinical characteristics and potential mechanisms.

OBJECTIVES: After resection of hypothalamic/pituitary tumors, children are at risk for development of hormonal deficiencies, obesity, and hypersomnolence. However, the prevalence and pathophysiology of these complications are unclear. The purpose of this study was to assess the prevalence and severity of hypersomnolence in children after resection of pituitary tumors and to study the potential factors that contribute to this sleepiness if present. We further hypothesized that decrements in orexin levels may contribute to the sleepiness. METHODS: Six children who underwent hypothalamic/pituitary surgery were identified. Five of these patients and 5 matched control subjects underwent overnight polysomnography followed by a multiple sleep latency test. Children who had a primary sleep disorder (eg, obstructive sleep apnea) underwent treatment and were restudied subsequently (n = 2). Blood levels of pituitary hormones were measured. Blood and cerebrospinal fluid (CSF) were drawn from 4 patients and 3 control subjects to measure orexin levels. RESULTS: Endocrine control was appropriate in all children. Although patients had longer sleep duration but similar sleep efficiency than control subjects, relatively severe daytime somnolence was present (mean sleep latency: 10.3 +/- 5.3 minutes vs 26.2 +/- 1.1 minute in control subjects). Sleepiness did not correlate with body mass index or age. Furthermore, serum and CSF orexin levels did not differ between patients and control subjects. CONCLUSIONS: Severe daytime sleepiness is frequent among children who undergo pituitary/hypothalamic surgery and does not seem to result from inappropriate cortisol or thyroxine replacement, disturbed nocturnal sleep, or low levels of orexin in the serum or CSF. We therefore speculate that other, unidentified neurohormonal mechanisms may mediate the excessive sleepiness of these patients.

Adolescent↗

PubMed2000

Post-traumatic stress disorder and sleep-what a nightmare!

According to DSM IV criteria, sleep disturbances are incorporated in the definition of post-traumatic stress disorder (PTSD). These include the re-experiencing symptoms (nightmares, criteria B) and a hyperarousal state (difficulty initiating and maintaining sleep, criteria D). PTSD patients commonly complain of sleep disturbances. Moreover, insomnia, restless sleep and trauma-related dreams might be the primary complaint of some patients. However, although subjective sleep disturbances are considered characteristic of PTSD, sleep laboratory studies have provided inconsistent evidence of objective sleep disorders. A variety of sleep architectures and sleep patterns has been reported in PTSD. However, only a few studies have controlled for comorbidities. Thus, uncertainty exists to what extent the sustained complaints of sleep disturbances in chronic PTSD are specifically related to the impact of exposure to traumatic stress, or rather are a consequence of comorbid disorders. Specific changes in REM sleep suggest a pathophysiologic role of REM sleep abnormality in PTSD (e.g. anxiety dreams, increased REM density, exaggerated startle response, decreased dream recall and elevated awakening thresholds from REM sleep). However, again, studies have failed to show consistent changes in percentage of REM sleep or in REM latency. There might be a coexistence of pressure to REM along with inhibitory forces of REM that result in high variability of REM parameters across patients. Alternatively, changes in REM sleep might reflect the effect of comorbid psychiatric disorders that results in inconsistent findings between patients. The current review tries to address these issues based on recent studies carried out in this field.

Journal Article↗