The relationship between periodic limb movement during sleep and dyslipidaemia in patients with obstructive sleep apnea

Periodic limb movements during sleep and obstructive sleep apnea are both associated with increased sympathetic tone, and have been proposed as risk factors for heart diseases and, in particular, cardiovascular disease. As sympathetic system activation may lead to dyslipidaemia, periodic limb movements during sleep could be an additional risk factor for cardiovascular disease in patients with obstructive sleep apnea. The aim of the study was to determine whether the presence of periodic limb movements during sleep affects serum lipid levels in obstructive sleep apnea. Total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, non- high-density lipoprotein cholesterol and triglyceride levels were investigated in 4138 patients with obstructive sleep apnea in the European Sleep Apnea Database (ESADA) cohort, divided into those with periodic limb movements during sleep index ≥ 15 per hr (n = 628) and controls (n = 3510). ANCOVA adjusted for age, sex, body mass index, apnea-hypopnea index, alcohol intake, smoking status, diabetes, insomnia and study site was used to assess differences in lipids between periodic limb movements during sleep and controls. Patients with periodic limb movements during sleep (24% female, 54.4 ± 12.1 years, body mass index 31.9 ± 5.8 kg m-2 , apnea-hypopnea index 36.7 ± 25.4 per hr) had higher triglyceride (1.81 ± 1.04 versus 1.69 ± 0.90 mmol L-1 , p = 0.002) and lower high-density lipoprotein cholesterol (1.19 ± 0.34 versus 1.24 ± 0.37 mmol L-1 , p = 0.002) levels, whilst there was no difference in either total cholesterol (4.98 ± 1.10 versus 4.94 ± 1.07 mmol L-1 ), low-density lipoprotein cholesterol (3.04 ± 0.96 versus 2.98 ± 0.98 mmol L-1 ) or non- high-density lipoprotein cholesterol (3.78 ± 1.10 versus 3.70 ± 1.05 mmol L-1 ) concentrations (all p > 0.05). The results remained unchanged after most sensitivity analyses. Patients with obstructive sleep apnea with periodic limb movements during sleep had more prevalent cardiovascular disease (11% versus 6%, p < 0.01). Periodic limb movements during sleep in obstructive sleep apnea is associated with dyslipidaemia independently of important confounders. Our results highlight periodic limb movements during sleep as an additional risk factor for cardiovascular disease in obstructive sleep apnea.

Serum Urotensin II Levels Are Elevated in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) has become major public concern and is continuously investigated in new aspects of pathophysiology and management. Urotensin II (UII) is a powerful vasoconstrictor with a role in cardiovascular diseases. The main goal of this study was to evaluate serum UII levels in OSA patients and matched controls. A total of 89 OSA patients and 89 controls were consecutively enrolled. A medical history review and physical examination of the participants was conducted, with polysomnography performed in the investigated group. UII levels and other biochemical parameters were assessed according to the standard laboratory protocols. The median AHI in the OSA group was 39.0 (31.4-55.2) events/h, and they had higher levels of hsCRP when compared to control group (2.87 ± 0.71 vs. 1.52 ± 0.68 mg/L; p < 0.001). Additionally, serum UII levels were significantly higher in the OSA group (3.41 ± 1.72 vs. 2.18 ± 1.36 ng/mL; p < 0.001), while positive correlation was found between UII levels and hsCRP (r = 0.450; p < 0.001) and systolic blood pressure (SPB) (r = 0.317; p < 0.001). Finally, multiple regression analysis showed significant association of UII levels with AHI (0.017 ± 0.006, p = 0.013), SBP (0.052 ± 0.008, p < 0.001) and hsCRP (0.538 ± 0.164, p = 0.001). As UII levels were associated with blood pressure and markers of inflammation and OSA severity, it might play an important role in the complex pathophysiology of OSA and its cardiometabolic complications.

Sleep and Lifestyle Habits of Medical and Non-Medical Students during the COVID-19 Lockdown

It has been shown that the measures of social distancing and lockdown might have had negative effects on the physical and mental health of the population. We aim to investigate the sleep and lifestyle habits as well as the mood of Croatian medical (MS) and non-medical students (NMS) during the COVID-19 lockdown. The cross-sectional study included 1163 students (21.6% male), whose lifestyle and sleep habits and mood before and during the lockdown were assessed with an online questionnaire. The shift towards later bedtimes was more pronounced among NMS (~65 min) compared to MS (~38 min), while the shift toward later wake-up times was similar in both MS (~111 min) and NMS (~112 min). All students reported more frequent difficulty in falling asleep, night-time awakenings and insomnia (p < 0.001) during lockdown. A higher proportion of MS reported being less tired and less anxious during lockdown compared to pre-lockdown (p < 0.001). Both student groups experienced unpleasant moods and were less content during lockdown compared to the pre-lockdown period (p < 0.001). Our results emphasize the need for the promotion of healthy habits in the youth population. However, the co-appearance of prolonged and delayed sleep times along with decreased tiredness and anxiety among MS during lockdown reveals their significant workload during pre-lockdown and that even subtle changes in their day schedule might contribute to the well-being of MS.

The Associations between Results in Different Domains of Cognitive and Psychomotor Abilities Measured in Medical Students

We aimed to investigate the associations between intelligence quotient test scores obtained using the Raven's Advanced Progressive Matrices (APM) and psychomotor testing using the Complex Reactionmeter Drenovac (CRD) test battery, while taking into account previous theoretical approaches recognizing intelligent behavior as the cumulative result of a general biological speed factor reflected in the reaction time for perceptual detections and motor decisions. A total of 224 medical students at the University of Split School of Medicine were recruited. Their IQ scores were assessed using Raven's APM, while the computerized tests of CRD-series were used for testing the reaction time of perception to visual stimulus (CRD311), psychomotor limbs coordination task (CRD411), and solving simple arithmetic operations (CRD11). The total test-solving (TTST) and the minimum single-task-solving (MinT) times were analyzed. On the CRD11 test, task-solving times were shorter in students with higher APM scores (r = -0.48 for TTST and r = -0.44 for MinT; p < 0.001 for both). Negative associations between task-solving times and APM scores were reported on CRD311 (r = -0.30 for TTST and r = -0.33 for MinT, p < 0.001 for both). Negative associations between task-solving times in CRD411 and APM scores (r = -0.40 for TTST and r = -0.30 for MinT, p < 0.001 for both) were found. Faster reaction time in psychomotor limbs coordination tasks, the reaction time of perception to visual stimulus, and the reaction time of solving simple arithmetic operations were associated with a higher APM score in medical students, indicating the importance of mental speed in intelligence test performance. However, executive system functions, such as attention, planning, and goal weighting, might also impact cognitive abilities and should be considered in future research.

Baseline clusters and the response to PAP treatment in obstructive sleep apnea patients – longitudinal data from the ESADA cohort

Introduction

The European Sleep Apnea Database was used to identify distinguishable obstructive sleep apnoea (OSA) phenotypes and to investigate the clinical outcome during positive airway pressure (PAP) treatment.

Method

Prospective OSA patient data were recruited from 35 sleep clinics in 21 European countries. Unsupervised cluster analysis (anthropometrics, clinical variables) was performed in a random sample (n=5000). Subsequently, all patients were assigned to the clusters using a conditional inference tree classifier. Responses to PAP treatment change in apnoea severity and Epworth sleepiness scale (ESS) were assessed in relation to baseline patient clusters and at short- and long-term follow-up.

Results

At baseline, 20 164 patients were assigned (mean age 54.1±12.2 years, 73% male, median apnoea–hypopnoea index (AHI) 27.3 (interquartile range (IQR) 14.1–49.3) events·h⁻¹, and ESS 9.8±5.3) to seven distinct clusters based on anthropometrics, comorbidities and symptoms. At PAP follow-up (median 210 [IQR 134–465] days), the observed AHI reduction (n=1075) was similar, whereas the ESS response (n=3938) varied: largest reduction in cluster 3 (young healthy symptomatic males) and 6 (symptomatic males with psychiatric disorders, −5.0 and −5.1 units, respectively (all p<0.01), limited reduction in clusters 2 (obese males with systemic hypertension) and 5 (elderly multimorbid obese males, −4.2 (p<0.05) and −3.7 (p<0.001), respectively). Residual sleepiness in cluster 5 was particularly evident at long-term follow-up (p<0.05).

Conclusion

OSA patients can be classified into clusters based on clinically identifiable features. Importantly, these clusters may be useful for prediction of both short- and long-term responses to PAP intervention.

20 164 patients from the European Sleep Apnea Database were assigned to seven phenotypic clusters at baseline. A limited reduction in daytime sleepiness following positive airway pressure treatment was shown in two out of seven clusters.https://bit.ly/3byAUHe

Management of obstructive sleep apnea in Europe - A 10-year follow-up

OBJECTIVE

In 2010, a questionnaire-based study on obstructive sleep apnea (OSA) management in Europe identified differences regarding reimbursement, sleep specialist qualification, and titration procedures. Now, 10 years later, a follow-up study was conducted as part of the ESADA (European Sleep Apnea Database) network to explore the development of OSA management over time.

METHODS

The 2010 questionnaire including questions on sleep diagnostic, reimbursement, treatment, and certification was updated with questions on telemedicine and distributed to European Sleep Centers to reflect European OSA management practice.

RESULTS

26 countries (36 sleep centers) participated, representing 20 ESADA and 6 non-ESADA countries. All 21 countries from the 2010 survey participated. In 2010, OSA diagnostic procedures were performed mainly by specialized physicians (86%), whereas now mainly by certified sleep specialists and specialized physicians (69%). Treatment and titration procedures are currently quite homogenous, with a strong trend towards more Autotitrating Positive Airway Pressure treatment (in hospital 73%, at home 62%). From 2010 to 2020, home sleep apnea testing use increased (76%-89%) and polysomnography as sole diagnostic procedure decreased (24%-12%). Availability of a sleep specialist qualification increased (52%-65%) as well as the number of certified polysomnography scorers (certified physicians: 36%-79%; certified technicians: 20%-62%). Telemedicine, not surveyed in 2010, is now in 2020 used in diagnostics (8%), treatment (50%), and follow-up (73%).

CONCLUSION

In the past decade, formal qualification of sleep center personnel increased, OSA diagnostic and treatment procedures shifted towards a more automatic approach, and telemedicine became more prominent.

Blockade of alpha2-adrenergic receptors in the caudal raphe region enhances the renal sympathetic nerve activity response to acute intermittent hypercapnia in rats

The study investigated the role of alpha2-adrenergic receptors of the caudal raphe region in the sympathetic and cardiovascular responses to the acute intermittent hypercapnia (AIHc). Urethane-anesthetized, vagotomized, mechanically ventilated Sprague-Dawley rats (n=38) were exposed to the AIHc protocol (5×3 min, 15 % CO2+50 % O2) in hyperoxic background (50 % O2). alpha2-adrenergic receptor antagonist-yohimbine was applied intravenously (1 mg/kg, n=9) or microinjected into the caudal raphe region (2 mM, n=12) prior to exposure to AIHc. Control groups of animals received saline intravenously (n=7) or into the caudal raphe region (n=10) prior to exposure to AIHc. Renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP) and heart rate (HR) were monitored before exposure to the AIHc protocol (T0), during five hypercapnic episodes (THc1-5) and at 15 min following the end of the last hypercapnic episode (T15). Following intravenous administration of yohimbine, RSNA was significantly greater during THc1-5 and at T15 than in the control group (P<0.05). When yohimbine was microinjected into the caudal raphe region, AIHc elicited greater increases in RSNA during THc1-5 when compared to the controls (THc1: 138.0+/-4.0 % vs. 123.7+/-4.8 %, P=0.032; THc2: 137.1+/-5.0 % vs. 124.1+/-4.5 %, P=0.071; THc3: 143.1+/-6.4 % vs. 122.0±4.8 %, P=0.020; THc4: 146.1+/-6.2 % vs. 120.7+/-5.7 %, P=0.007 and THc5: 143.2+/-7.7 % vs. 119.2+/-7.2 %, P=0.038). During THc1-5, significant decreases in HR from T0 were observed in all groups, while changes in MAP were observed in the group that received yohimbine intravenously. These findings suggest that blockade of the alpha2-adrenegic receptors in the caudal raphe region might have an important role in sympathetic responses to AIHc.

Sleep medicine catalogue of knowledge and skills - Revision

The 'catalogue of knowledge and skills' for sleep medicine presents the blueprint for a curriculum, a textbook, and an examination on sleep medicine. The first catalogue of knowledge and skills was presented by the European Sleep Research Society in 2014. It was developed following a formal Delphi procedure. A revised version was needed in order to incorporate changes that have occurred in the meantime in the International Classification of Sleep Disorders, updates in the manual for scoring sleep and associated events, and, most important, new knowledge in sleep physiology and pathophysiology. In addition, another major change can be observed in sleep medicine: a paradigm shift in sleep medicine has taken place. Sleep medicine is no longer a small interdisciplinary field in medicine. Sleep medicine has increased in terms of recognition and importance in medical care. Consequently, major medical fields (e.g. pneumology, cardiology, neurology, psychiatry, otorhinolaryngology, paediatrics) recognise that sleep disorders become a necessity for education and for diagnostic assessment in their discipline. This paradigm change is considered in the catalogue of knowledge and skills revision by the addition of new chapters.

The COVID-19 Lockdown and CPAP Adherence: The More Vulnerable Ones Less Likely to Improve Adherence?

PURPOSE

Due to the possible interplay of factors predisposing to severe COVID-19 outcomes and negative health consequences of poorly controlled OSA, adherence to continuous positive airway pressure (CPAP) therapy among OSA patients might be crucial during COVID-19 pandemics. Lockdown-related changes in CPAP adherence were investigated in CPAP users willing to participate in this study. Pre-lockdown adherence, age, gender, comorbidities and anxiety were analyzed as predictors of COVID-19 lockdown adherence.

PATIENTS AND METHODS

A cross-sectional study performed at Split Sleep Medicine Center included 101 severe OSA patients (78.2% male). CPAP memory cards were assessed during 6 months of pre-lockdown and 40 days of lockdown (March/April 2020) period. A total of 81 patients in pre-lockdown met good CPAP adherence criteria (≥4 hours/night on 70% nights).

RESULTS

CPAP adherence improved during COVID-19 lockdown in the total sample of severe OSA patients. The percentage of adherent nights and CPAP usage hours per night increased during lockdown in good pre-lockdown CPAP adherers (p=0.011 and p=0.001, respectively), women (p=0.003 and p=0.001, respectively) and respondents younger than 58 years (p=0.007 and p<0.001, respectively). Out of 20/101 poor pre-lockdown CPAP adherers, 9 have shifted to good lockdown adherence. When comorbidities, BMI and anxiety were taken into account, older and male respondents were recognized as less likely to improve CPAP usage hours during lockdown (R²=9.4%; p=0.032).

CONCLUSION

The lockdown-related CPAP adherence improved in severe OSA patients, with a shift in almost half of poor pre-lockdown adherers towards good lockdown CPAP adherence. Women, younger and good pre-lockdown CPAP adherers were more adherent during lockdown. Despite being vulnerable groups for both OSA and COVID-19, no expected adherence improvements were observed in men and older patients.

Auto-adaptive positive airway pressure improves lung function and arterial stiffness parameters in patients with severe obstructive sleep apnea syndrome over a 1 year follow-up

OBJECTIVE

Auto-adaptive positive airway pressure (APAP) is an emerging therapeutic modality for obstructive sleep apnea (OSA) patients. However, their associated physiological effects have not been well-defined. Therefore, we aimed to investigate the impact of a 1 year APAP treatment on lung function and arterial stiffness parameters.

APPROACH

This study enrolled male patients with newly diagnosed severe OSA who have undergone APAP treatment. A total of 35 patients completed a 1 year follow up. Blood pressure, arterial stiffness (PWV, cAIx, pAIx, cSBP), and lung function readings (FEV₁, FVC, FEV₁/FVC, PEF) were obtained basally and after 1, 3, 6, and 12 months of treatment.

MAIN RESULTS

A gradual increase in FEV₁ has been observed over the follow-up (2.92 ± 0.88 versus 3.07 ± 0.92 versus 3.18 ± 0.93 versus 3.28 ± 0.93 versus 3.41 ± 0.97 L), while PWV showed a gradual decrease over the follow-up (9.72 ± 1.64 versus 9.32 ± 1.73 versus 8.89 ± 1.65 versus 8.53 ± 1.61 versus 8.46 ± 1.60 m s^-1), as measured by absolute values. Linear mixed effects model analysis revealed a statistically significantly higher FEV₁ values (coefficient of 0.11, 0.20, and 0.33 for 3rd month, 6th month, and 12th month, respectively, P < 0.001) and lower PWV values (coefficient of -0.69, -0.63, and -0.34 for 3rd month, 6th month, and 12th month, respectively, P < 0.001), after the initiation of APAP treatment.

SIGNIFICANCE

We conclude that APAP treatment improves main lung function and arterial stiffness parameters in male patients with severe OSA over a 1 year follow-up.

Impact of Sleep Apnea on Cardioembolic Risk in Patients With Atrial Fibrillation: Data From the ESADA Cohort

BACKGROUND AND PURPOSE

An accurate determination of the cardioembolic risk in patients with atrial fibrillation (AF) is crucial to prevent consequences like stroke. Obstructive sleep apnea (OSA) is a known risk factor for both AF and stroke. We aim to explore a possible association between OSA and an increased cardioembolic risk in patients with AF.

METHODS

We assessed data from the ESADA (European Sleep Apnea Database) cohort where patients with known AF and OSA were included. Parameters of OSA severity and related hypoxia like lowest Spo₂ and 4% oxygen desaturation index were analyzed. Patients were stratified according to their cardioembolic risk estimated with the CHA₂DS₂-VASc score.

RESULTS

From the initial cohort of 14 646 patients, a final set of 363 patients were included in the analysis. Indices of hypoxia during sleep were associated with increased CHA₂DS₂-VASc score (4% oxygen desaturation index 17.9 versus 29.6 versus 30.5 events/hour and the lowest Spo₂ 81.2 versus 77.8 versus 77.5% for low, moderate, and high cardioembolic risk, respectively, P<0.05).

CONCLUSIONS

These results support the potential role of OSA-related hypoxia in the risk for cardioembolic complications such as stroke in patients with AF.

Clusters of sleep apnoea phenotypes: A large pan-European study from the European Sleep Apnoea Database (ESADA)

BACKGROUND AND OBJECTIVE

To personalize OSA management, several studies have attempted to better capture disease heterogeneity by clustering methods. The aim of this study was to conduct a cluster analysis of 23 000 OSA patients at diagnosis using the multinational ESADA.

METHODS

Data from 34 centres contributing to ESADA were used. An LCA was applied to identify OSA phenotypes in this European population representing broad geographical variations. Many variables, including symptoms, comorbidities and polysomnographic data, were included. Prescribed medications were classified according to the ATC classification and this information was used for comorbidity confirmation.

RESULTS

Eight clusters were identified. Four clusters were gender-based corresponding to 54% of patients, with two clusters consisting only of men and two clusters only of women. The remaining four clusters were mainly men with various combinations of age range, BMI, AHI and comorbidities. The preferred type of OSA treatment (PAP or mandibular advancement) varied between clusters.

CONCLUSION

Eight distinct clinical OSA phenotypes were identified in a large pan-European database highlighting the importance of gender-based phenotypes and the impact of these subtypes on treatment prescription. The impact of cluster on long-term treatment adherence and prognosis remains to be studied using the ESADA follow-up data set.

Feasibility study of determining a risk assessment model for obstructive sleep apnea in children based on local findings and clinical indicators

OBJECTIVE

To test a feasible and reliable model for diagnosing obstructive sleep apnea (OSA) in children, based on the clinically relevant parameters, in comparison to a polysomnography.

METHODS

A total of 94 children with the suspected underlying OSA were included in the analyses. An association between clinical parameters (modified Mallampati score, tonsil size, adenoid size, age, gender, and body mass index) and apnea-hypopnea index (AHI) obtained following an overnight polysomnography was assessed, and significant variables were incorporated in the logistic regression model. Also, the sensitivity and specificity calculations of the model with the inclusion of ROC curve analysis were performed.

RESULTS

All tee local clinical parameters were significantly associated with AHI (P < 0.001). The most significant correlation with AHI was shown with the modified Mallampati score (r = 0.723), following with tonsil size (r = 0.673), and adenoid size (r = 0.502). The sensitivity of the tested model was 84%, and specificity was 74%.

CONCLUSION

This study derived a model based on the local clinical findings that significantly overlapped with the results of an overnight polysomnography, in diagnosing OSA in children.

Health-Related Quality of Life in Patients After Surgically Treated Midface Fracture: A Comparison with the Croatian Population Norm

Aim

To evaluate the health-related life quality of patients after surgically treated midface fractures.

Patients and Methods

This retrospective cohort study compared the 36-Item Short Form Health Survey (SF-36) scores of 42 male patients following surgically treated maxillary or zygomatic fractures with the reported normative data of the SF-36 for the Croatian population.

Results

The current study showed that the health-related life quality of surgically treated patients was comparable to similar age, gender, and regional demographics in the Croatian population norm. However, we revealed a significant deterioration of the “Emotional wellbeing” domain in younger patients (P = 0.03) and a severely affected domain of “Physical functioning” in older patients (P = 0.049).

Conclusion

There was a significant negative psychological impact from facial trauma on younger patients. In contrast, older patients were more prone to physical impairment. Therefore, follow-up visits are an opportunity to screen and refer younger patients to mental health services in a timely manner to prevent severe psychological difficulties and an opportunity to identify older patients who require physical therapy.

Bone metabolism parameters and inactive matrix Gla protein in patients with obstructive sleep apnea†

STUDY OBJECTIVES

The aim of this study was to investigate differences in dual-energy X-ray absorptiometry (DXA) parameters, trabecular bone score (TBS), bone turnover markers and inactive matrix Gla protein (dp-ucMGP) between patients with obstructive sleep apnea (OSA) and healthy controls.

METHODS

This study enrolled 53 male patients diagnosed with OSA, and 50 age- and body mass index (BMI)-matched control subjects. All participants underwent DXA imaging, TBS assessment and blood sampling for biochemical analysis of bone metabolism markers.

RESULTS

Mean apnea-hypopnea index (AHI) score of OSA patients was 43.8 ± 18.8 events/h. OSA patients had significantly higher plasma dp-ucMGP levels in comparison to controls (512.7 ± 71.9 vs. 465.8 ± 50.9 pmol/L, p < 0.001). OSA and control group did not significantly differ regarding standard DXA results, while TBS values were significantly lower in the OSA group (1.24 ± 0.17 vs. 1.36 ± 0.15, p < 0.001). AHI score was a significant independent correlate of plasma dp-ucMGP levels (β ± SE, 1.461 ± 0.45, p = 0.002). In addition, TBS retained a significant relationship with dp-ucMGP values (β ± SE, -93.77 ± 38.1, p = 0.001).

CONCLUSIONS

dp-ucMGP levels are significantly higher in patients with OSA and correlate with disease severity. In addition, TBS values in OSA patients are lower in comparison with the control group and decrease with disease severity.

Hyperoxia blunts renal sympathetic nerve activity response to acute intermittent hypercapnia in rats

Activation of the sympathetic nervous system plays an important role in the pathophysiology of sleep-related breathing disorders. The aim of the present study was to examine the effects of different levels of hypercapnia in the presence of various background oxygen levels on the magnitude of sympathoexcitation, measured by the renal sympathetic nerve activity (RSNA) in the acute intermittent hypercapnia (AIHc) rat model. The study was conducted on 56 urethane-anesthetized, vagotomized and mechanically ventilated Sprague-Dawley rats (n = 7/group). Each experimental group was subjected to a distinct AIHc protocol that varied in the applied levels of hypercapnia and background oxygen. Mean arterial pressure and RSNA were analyzed in 7 experimental time points: baseline, five hypercapnic episodes (each lasting 3 min) and 15 minutes following the last hypercapnic episode. Exposure to severe hypercapnia (FiCO₂ = 0.15) evoked an increase in RSNA, which was preserved throughout the protocol, whereas in moderate hypercapnia (FiCO₂ = 0.05) groups there was a trend of progressive diminution of RSNA magnitude following the first hypercapnic episode. Exposure to severe hypercapnia elicited significantly greater RSNA response during first hypercapnic episode and it was enhanced during subsequent episodes compared to exposure to moderate hypercapnia. Additionally, hyperoxic₂ background (50% O₂) blunted the RSNA response to AIHc compared to room air background, both in severe and moderate hypercapnia groups. Mean arterial blood pressure was preserved throughout the experimental protocol in all studied groups. These findings indicate that acute intermittent hypercapnia evokes increased renal sympathetic nerve activity that is dependent on the severity of hypercapnic exposures and the background oxygen level.

Psychomotor Performance in Patients with Obstructive Sleep Apnea Syndrome

PURPOSE

Determinants of obstructive sleep apnea (OSA) are hypoxemia and hypercapnia, as well as (micro) arousals from sleep, resulting in chronic sleep fragmentation, sleep deprivation, and excessive daytime sleepiness (EDS). All of the above-mentioned factors might contribute to psychomotor impairment seen in OSA patients. Additionally, this study aimed to assess the contribution of BMI, age, EDS assessed with Epworth sleepiness scale (ESS), and severity of OSA assessed with apnea-hypopnea index (AHI) to the reaction time on chronometric tests in OSA patients and controls. It is hypothesized that moderate and severe OSA have adverse effects on reaction time of perception to visual stimulus, of solving simple arithmetic operations, and of psychomotor limbs coordination assessed by chronometric psychodiagnostic test battery.

PATIENTS AND METHODS

This study was conducted on 206 male participants; 103 of them had moderate or severe OSA diagnosed by whole-night polysomnography/polygraphy. Control participants (N=103), matched to patients with OSA by age and BMI, had no reported OSA in their medical history, no increased risk for OSA, nor EDS. All participants were assessed with three chronometric psychodiagnostic tests, measuring the reaction time of perception to visual stimulus, of solving simple arithmetic operations, and of psychomotor limbs coordination.

RESULTS

Participants from the OSA group achieved impaired results compared to control participants in minimum single task solving time in speed of solving simple arithmetic operations (3±0.9 and 2.6±0.6, P<0.001), and in minimum solving time of a single task in complex psychomotor limbs coordination (0.69±0.2 and 0.61±0.1, P=0.007). Regression analysis revealed no significant contribution of daytime sleepiness to the results achieved in each of the tests.

CONCLUSION

It is concluded that severe OSA impaired speed of perception, convergent, and operative thinking. Moreover, it is suggested that EDS did not contribute to poor psychomotor outcome in patients with OSA in this study, when age was controlled for.

Prevalence of obstructive sleep apnea in male patients with surgically treated maxillary and zygomatic fractures

Background

Midface fractures can cause airway obstruction and breathing disturbances. The purpose of the present study was to determine the prevalence of undiagnosed obstructive sleep apnea (OSA) among patients with surgically treated maxillary and zygomatic fractures.

Methods

We retrospectively analyzed the medical records of 44 patients who had undergone surgical treatment of maxillary or zygomatic fractures between Jan. 1, 2003, and Dec. 31, 2013 at a single centre. All participants underwent polygraphy testing and were asked to complete the STOP (snoring, tiredness, observed apnea and high blood pressure) questionnaire, Nasal Obstruction Symptom Evaluation (NOSE) scale and Epworth Sleepiness Scale.

Results

There were 27 participants (61%) with maxillary fracture and 17 (39%) with zygomatic fracture. Obstructive sleep apnea was diagnosed in 24 (54%) of the 44 participants, of whom 15 (62%) had maxillary fractures and 9 (38%) had zygomatic fractures. Participants with OSA had a mean Apnea–Hypopnea Index (AHI) of 15.5 (standard deviation [SD] 9.7) events/h, compared to 2.4 (SD 1.5) events/h for those without OSA (p < 0.001). Of the 30 participants with nose obstruction, 18 (60%) had an AHI of 5 or greater.

Conclusion

The results suggest that the prevalence of OSA was higher in surgical patients with midface fractures, independent of the type of fracture, than in the general population. The NOSE scale results showed significant correlation with the presence of OSA.

Sleep-disordered breathing is associated with brain vascular reactivity in spinal cord injury

OBJECTIVE

To determine the population-level odds of individuals with spinal cord injury (SCI) experiencing fatigue and sleep apnea, to elucidate relationships with level and severity of injury, and to examine associations with abnormal cerebrovascular responsiveness.

METHODS

We used population-level data, meta-analyses, and primary physiologic assessments to provide a large-scale integrated assessment of sleep-related complications after SCI. Population-level and meta-analyses included more than 60,000 able-bodied individuals and more than 1,800 individuals with SCI. Physiologic assessments were completed on a homogenous sample of individuals with cervical SCI and matched controls. We examined the prevalence of (1) self-reported chronic fatigue, (2) clinically identified sleep apnea, and 3) cerebrovascular responsiveness to changing CO₂.

RESULTS

Logistic regression revealed a 7-fold elevated odds of chronic fatigue after SCI (odds ratio [OR] 7.9, 95% confidence interval [CI] 3.5-16.2), and that fatigue and trouble sleeping are correlated with the level and severity of injury. We further show that those with SCI experience elevated risk of clinically defined sleep-disordered breathing in more than 600 individuals with SCI (pooled OR 3.1, 95% CI 1.3-7.5). We confirmed that individuals with SCI experience a high rate of clinically defined sleep apnea using primary polysomnography assessments. We then provide evidence using syndromic analysis that sleep-disordered breathing is a factor strongly associated with impaired cerebrovascular responsiveness to CO₂ in patients with SCI.

CONCLUSIONS

Individuals with SCI have an increased prevalence of sleep-disordered breathing, which may partially underpin their increased risk of stroke. There is thus a need to integrate sleep-related breathing examinations into routine care for individuals with SCI.

Adropin and Inflammation Biomarker Levels in Male Patients With Obstructive Sleep Apnea: A Link With Glucose Metabolism and Sleep Parameters

STUDY OBJECTIVES

The main objectives of the study were to determine plasma adropin, systemic inflammation biomarker levels, and glucose metabolism parameters in patients with moderate and severe obstructive sleep apnea (OSA) compared to healthy controls.

METHODS

In this study, we included 50 male patients with OSA (25 moderate and 25 severe) and 25 age- and sex-matched control subjects. All subjects underwent fasting sampling of peripheral blood for laboratory analyses.

RESULTS

Adropin plasma levels were significantly lower in the severe OSA group in comparison with the moderate and control groups (4.50 ± 1.45 versus 6.55 ± 1.68 versus 8.15 ± 1.79 ng/mL, P < .001). Plasma biomarkers of systemic inflammation were significantly increased in patients with moderate OSA (interleukin [IL]-6 and tumor necrosis factor alpha [TNF-α]) and severe OSA (IL-6, TNF-α, high-sensitivity C-reactive protein) when compared with controls (P < .001). Adropin levels showed a significant negative correlation with IL-6 (r = -.419, P < .001), TNF-α (r = -.540, P < .001), fasting glucose (r = -.331, P = .004), hemoglobin A1c (r = -.438, P < .001), homeostatic model assessment insulin resistance index (r = -.213, P = .046), and polysomnographic parameters including apnea-hypopnea index (r = -.615, P < .001) and oxygen desaturation index (r = -.573, P < .001). A multivariate regression analysis showed that plasma adropin remained as a significant negative predictor of severe OSA status, when adjusted for age and body mass index and computed along with other inflammatory biomarkers in the regression model (odds ratio 0.069, 95% confidence interval 0.009-0.517, P = .009).

CONCLUSIONS

Plasma adropin concentrations significantly correlate with indices of disease severity in patients with OSA, suggesting that adropin potentially plays an important role in the complex pathophysiology of the disease.

Clinical presentation of patients with suspected obstructive sleep apnea and self-reported physician-diagnosed asthma in the ESADA cohort

Obstructive sleep apnea (OSA) and asthma are often associated and several studies suggest a bidirectional relationship between asthma and OSA. This study analyzed the characteristics of patients with suspected OSA from the European Sleep Apnea Database according to presence/absence of physician-diagnosed asthma. Cross-sectional data in 16,236 patients (29.1% female) referred for suspected OSA were analyzed according to occurrence of physician-diagnosed asthma for anthropometrics, OSA severity and sleepiness. Sleep structure was assessed in patients studied by polysomnography (i.e. 48% of the sample). The prevalence of physician-diagnosed asthma in the entire cohort was 4.8% (7.9% in women, 3.7% in men, p < 0.0001), and decreased from subjects without OSA to patients with mild-moderate and severe OSA (p = 0.02). Obesity was highly prevalent in asthmatic women, whereas BMI distribution was similar in men with and without physician-diagnosed asthma. Distribution of OSA severity was similar in patients with and without physician-diagnosed asthma, and unaffected by treatment for asthma or gastroesophageal reflux. Asthma was associated with poor sleep quality and sleepiness. Physician-diagnosed asthma was less common in a sleep clinic population than expected from the results of studies in the general population. Obesity appears as the major factor raising suspicion of OSA in asthmatic women, whereas complaints of poor sleep quality were the likely reason for referral in asthmatic men.

Phrenic long-term depression evoked by intermittent hypercapnia is modulated by serotonergic and adrenergic receptors in raphe nuclei

Intermittent hypercapnia evokes prolonged depression of phrenic nerve activity (phrenic long-term depression, pLTD). This study was undertaken to investigate the role of 5-HT and α2-adrenergic receptors in the initiation of pLTD. Adult male urethane-anesthetized, vagotomized, paralyzed, and mechanically ventilated Sprague-Dawley rats were exposed to a protocol of acute intermittent hypercapnia (AIHc; 5 episodes of 15% CO2in air, each episode lasting 3 min). The experimental group received microinjection of the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT), the broad-spectrum 5-HT antagonist methysergide, or the α2-adrenergic antagonist yohimbine, whereas the control group received microinjection of 0.9% saline into the caudal raphe region. Peak phrenic nerve activity (pPNA) and burst frequency ( f) were analyzed during baseline (T0), during 5 hypercapnic episodes (THc1–THc5), and at 15, 30, and 60 min after the end of the last hypercapnic episode. In the control group, pPNA decreased 60 min after the end of the last hypercapnic episode compared with baseline values, i.e., pLTD developed ( P = 0.023). In the 8-OH-DPAT group, pPNA significantly decreased at T15, T30, and T60 compared with baseline values, i.e., pLTD developed ( P = 0.01). In the methysergide and yohimbine groups, AIHc did not evoke significant changes of the pPNA at T15, T30, and T60 compared with baseline values. In conclusion, activation of 5-HT1Areceptors accentuated induction of pLTD, whereas blockade of α2-adrenergic receptors prevented development of pLTD following AIHc in anesthetized rats. These results suggest that chemical modulation of 5-HT and α2-adrenergic receptors in raphe nuclei affects hypercapnia-induced pLTD, offering important insights in understanding the mechanisms involved in development of respiratory plasticity.

NEW & NOTEWORTHY Hypercapnia is a concomitant feature of many breathing disorders, including obstructive sleep apnea. In this study, acute intermittent hypercapnia evoked development of phrenic long-term depression (pLTD) 60 min after the last hypercapnic episode that was preserved if the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide was microinjected in the caudal raphe region before the hypercapnic stimulus. This study highlights that both 5-HT and adrenergic receptor activation is needed for induction of pLTD in urethane-anesthetized rats following intermittent hypercapnia exposure.

Effects of CPAP therapy on cognitive and psychomotor performances in patients with severe obstructive sleep apnea: a prospective 1-year study

STUDY OBJECTIVES

We prospectively investigated the effects of continuous positive airway pressure (CPAP) on long-term cognitive and psychomotor performances, and excessive daytime sleepiness in severe obstructive sleep apnea (OSA) patients.

METHODS

A total of 40 patients were recruited and 23 patients with severe OSA fully completed the study protocol to investigate the effects of CPAP therapy on psychomotor performance at 1, 3, and 6 months and 1 year following initiation of the therapy. Psychomotor CRD-series tests measuring reaction times of light stimulus perception, solving simple arithmetic operations, and complex psychomotor limb coordination, were used in this study. The data collected following CPAP therapy were compared to baseline values prior to the CPAP treatment for each patient.

RESULTS

All of the measured variables improved following CPAP treatment. However, the most pronounced effect was observed in improvement of reaction times to complex psychomotor limb coordination test (p < 0.05). Self-reported evaluation of excessive daytime sleepiness measured by Epworth Sleepiness Scale (ESS) showed significant decrease from 10.0 ± 1.1 before to 3.5 ± 0.5 (p < 0.001), after 1 year on CPAP therapy.

CONCLUSIONS

The CPAP therapy improved cognitive and psychomotor performance on CRD-series tests with the most significant improvement observed in complex psychomotor limb coordination of severe OSA patients.

Improvement of Cognitive and Psychomotor Performance in Patients with Mild to Moderate Obstructive Sleep Apnea Treated with Mandibular Advancement Device: A Prospective 1-Year Study

STUDY OBJECTIVES

This study aimed to provide the evidence on effect of mandibular advancement device (MAD) therapy on long-term cognitive and psychomotor performance, excessive daytime sleepiness, and quality of life in patients with mild to moderate obstructive sleep apnea (OSA).

METHODS

A total of 15 patients with mild to moderate OSA were treated with MAD therapy and they were followed up after 3 mo and 1 y of therapy. The patients were tested on three different tests of cognitive and psychomotor performance using the computer-based system Complex Reactionmeter Drenovac (CRD-series) at baseline and at the time of follow-up, and the 36-Item Short Form Health Survey (SF-36) questionnaire and Epworth Sleepiness Scale were used to assess their quality of life and excessive daytime sleepiness, respectively.

RESULTS

The mean apnea-hypopnea index (AHI) decreased significantly from 22.9 ± 5.9 events/h at baseline, to 9.7 ± 4.5 events/h after 1 y of MAD therapy (p < 0.001). There was significant improvement on all three CRD-series tests used after 1 y of MAD therapy, considering total test solving time (TTST) and minimal single task solving time (MinT), whereas total number of errors committed during the tests (TE) remained unchanged. Self-reported measures, excessive daytime sleepiness, and three domains of quality of life, social functioning, general health perception, and health change following MAD therapy showed significant improvements after 1 y of MAD therapy.

CONCLUSIONS

This study demonstrates significant improvements in cognitive and psychomotor performance, particularly in the domain of perceptive abilities, convergent thinking (constructing and solving simple mathematical tasks) and psychomotor reaction times, excessive daytime sleepiness, and quality of life in patients with mild to moderate OSA following MAD therapy.

Genetic variants in RBFOX3 are associated with sleep latency

Time to fall asleep (sleep latency) is a major determinant of sleep quality. Chronic, long sleep latency is a major characteristic of sleep-onset insomnia and/or delayed sleep phase syndrome. In this study we aimed to discover common polymorphisms that contribute to the genetics of sleep latency. We performed a meta-analysis of genome-wide association studies (GWAS) including 2 572 737 single nucleotide polymorphisms (SNPs) established in seven European cohorts including 4242 individuals. We found a cluster of three highly correlated variants (rs9900428, rs9907432 and rs7211029) in the RNA-binding protein fox-1 homolog 3 gene (RBFOX3) associated with sleep latency (P-values=5.77 × 10(-08), 6.59 × 10(-)(08) and 9.17 × 10(-)(08)). These SNPs were replicated in up to 12 independent populations including 30 377 individuals (P-values=1.5 × 10(-)(02), 7.0 × 10(-)(03) and 2.5 × 10(-)(03); combined meta-analysis P-values=5.5 × 10(-07), 5.4 × 10(-07) and 1.0 × 10(-07)). A functional prediction of RBFOX3 based on co-expression with other genes shows that this gene is predominantly expressed in brain (P-value=1.4 × 10(-316)) and the central nervous system (P-value=7.5 × 10(-)(321)). The predicted function of RBFOX3 based on co-expression analysis with other genes shows that this gene is significantly involved in the release cycle of neurotransmitters including gamma-aminobutyric acid and various monoamines (P-values<2.9 × 10(-11)) that are crucial in triggering the onset of sleep. To conclude, in this first large-scale GWAS of sleep latency we report a novel association of variants in RBFOX3 gene. Further, a functional prediction of RBFOX3 supports the involvement of RBFOX3 with sleep latency.

Morning cortisol levels and glucose metabolism parameters in moderate and severe obstructive sleep apnea patients

Obstructive sleep apnea (OSA) has been associated with dysregulation of the hypothalamic-pituitary-adrenal axis and alterations in glucose metabolism with increased risk for type 2 diabetes. The aim of the current study was to compare morning plasma cortisol levels and glucose metabolism parameters between moderate (apnea-hypopnea index (AHI): 15-30 events/h) and severe OSA patients (AHI >30 events/h), with respective controls. A total of 56 male OSA patients, 24 moderate (AHI = 21.1 ± 5.3) and 32 severe (AHI = 49.7 ± 18.1), underwent a full-night polysomnography, oral glucose tolerance test (OGTT), and measurement of morning plasma cortisol levels. These groups were compared to 20 matched subjects in a control group. Morning plasma cortisol levels were statistically lower in severe OSA group than in moderate OSA and control groups (303.7 ± 93.5 vs. 423.9 ± 145.1 vs. 417.5 ± 99.8 pmol/L, P < 0.001). Significant negative correlations were found between morning plasma cortisol levels and AHI (r = -0.444, P = 0.002), as well as oxygen desaturation index (r = -0.381, P = 0.011). Fasting plasma glucose (5.0 ± 0.5 vs. 5.4 ± 0.7 vs. 4.9 ± 0.6 mmol/L, P = 0.009) was higher in the severe OSA group compared to moderate OSA and controls. Homeostasis model assessment insulin resistance (HOMA-IR) was higher in the severe OSA group compared to moderate OSA and controls (4.6 ± 3.7 vs. 2.7 ± 2.0 and 2.2 ± 1.8, respectively, P = 0.006). In conclusion, our study showed that morning plasma cortisol levels measured at 8 a.m. were significantly lower in severe OSA patients than those in moderate OSA group and controls. Morning plasma cortisol levels showed a negative correlation with AHI and oxygen desaturation index. Additionally, this study confirmed the evidence of glucose metabolism impairment in moderate and severe OSA patients, with more pronounced effect in the severe OSA patients group.

The relationship between sleep habits and academic performance in dental students in Croatia

INTRODUCTION

It is well accepted that sleep and lifestyle habits affect academic success in students. However, sleep patterns and sleep problems amongst dental students have been insufficiently addressed in the literature. The purpose of this study was to evaluate sleep habits of dental students and the relationship between sleep habits and academic performance.

MATERIALS AND METHODS

A self-administered questionnaire on sleep habits, academic performance and lifestyle was administered. The participants were 447 dental students from Split University Dental Medicine School and Zagreb University Dental Medicine School from the six academic years. The subjects were classified into two groups based on academic success (high-performing vs. low-performing students) for comparison of sleep and lifestyle habits.

RESULTS

Amongst the whole group of students, average bedtime and wake time during weekday was significantly earlier compared with weekend. Main findings indicate that students with high academic performance had earlier bedtimes during weekdays and weekends, earlier wake times during weekends and shorter sleep latency compared with low academic performing students.

CONCLUSION

Self-reported academic performance of dental students in Croatia is associated with timing of sleep and wakefulness, rather than with total sleep time duration.

Remifentanil reversibly abolished phrenic long term facilitation in rats subjected to acute intermittent hypoxia

The aim was to investigate whether intravenous infusion of remifentanil would depress phrenic long term facilitation (pLTF) evoked by acute intermittent hypoxia (AIH) in adult, male, urethane anaesthetized Sprague-Dawley rats, bilaterally vagotomized, paralyzed and mechanically ventilated. The experimental group received a remifentanil infusion (0.5 μg/kg/min i.v., n=12), whereas the control group (n=6) received saline. Rats were exposed to AIH protocol. Phrenic nerve amplitude (PNA), burst frequency (f) and breathing rhythm parameters (Ti, Te, Ttot) were analyzed during 5 hypoxias and at 15, 30, and 60 minutes after the final hypoxia, and compared to baseline values. At the end of the experiment, the infusion of remifentanil was stopped and phrenic nerve activity was compared to baseline values prior to remifentanil infusion. In the control group, peak phrenic nerve activity (pPNA) significantly increased at 60 min (T60, increase by 138.8±28.3%, p=0.006) after the last hypoxic episode compared to baseline values, i.e. pLTF was induced. In remifentanil treated rats, there were no significant changes in peak phrenic nerve activity at T60 compared to baseline values (decrease by 5.3±16.5%, p>0.05), i.e. pLTF was abolished. Fifteen minutes following cessation of remifentanil infusion, pPNA increased by 93.2±40.2% (p<0.05) and remained increased compared to pre-remifentanil-infusion values for more than 30 minutes, i.e. pLTF could be observed after cessation of the remifentanil infusion. In conclusion, the short acting μ-opioid receptor agonist, remifentanil, reversibly abolished phrenic long term facilitation in urethane anesthetized rats.

Craniofacial morphology of Croatian patients with obstructive sleep apnea

Currently, there is no information available regarding craniofacial morphology of Croatian patients with obstructive sleep apnea (OSA). The aim of the study was to determine the craniofacial characteristics of patients with OSA and to assess the association of cephalometric and anthropometric variables related to craniofacial morphology with the apnea hypopnea index (AHI). Anthropometric measurements and upright lateral cephalometric radiographs were obtained from 20 male patients with OSA and 20 male controls. The 20 OSA patients were classified into two groups on the basis of body mass index (BMI) as obese and non-obese. Twenty three variables were identified and calculated for each cephalometric radiograph. OSA was defined as AHI > or = 5/hour. The OSA patients showed greater body mass index (BMI), neck circumference (NC) and cranial index (CI) and lower facial index (FI) compared to the controls (p < 0.01). The patients with OSA showed significant cephalometric features as opposed to the controls: smaller linear distance between gonion and menton and anterior cranial base, greater linear distance from the hyoid bone to the mandibular plane, and from the posterior nasal spine to the tip of the soft palate. Furthermore, they showed reduced upper airway width at two levels: the nasopharynx, and the region of posterior airway space, smaller linear distance from the hyoid bone to the posterior wall of the nasopharynx and greater upper airway length. They also displayed significantly increased craniocervical angulation, larger angle between supramentale, menton and hyoid bone and larger angle between posterior nasal spine, supramentale and hyoid bone. The obese OSA patients showed greater neck circumference (NC) compared with the non-obese OSA. The obese OSA patients showed significant cephalometric features compared with the non-obese OSA patients: larger craniocervical angles larger angle between the third cervical vertebra, the centre of sella turcica and the posterior nasal spine, furthermore, greater linear distance between the hyoid bone and the third cervical vertebra and smaller linear distance from the hyoid bone to the posterior wall of the nasopharynx. In our study, AHI was significantly correlated with cephalometric measurements S-Go, S-H, H-C3 and S-PNS-C3.

A K(ATP) channel gene effect on sleep duration: from genome-wide association studies to function in Drosophila

Humans sleep approximately a third of their lifetime. The observation that individuals with either long or short sleep duration show associations with metabolic syndrome and psychiatric disorders suggests that the length of sleep is adaptive. Although sleep duration can be influenced by photoperiod (season) and phase of entrainment (chronotype), human familial sleep disorders indicate that there is a strong genetic modulation of sleep. Therefore, we conducted high-density genome-wide association studies for sleep duration in seven European populations (N=4251). We identified an intronic variant (rs11046205; P=3.99 × 10(-8)) in the ABCC9 gene that explains ≈5% of the variation in sleep duration. An influence of season and chronotype on sleep duration was solely observed in the replication sample (N=5949). Meta-analysis of the associations found in a subgroup of the replication sample, chosen for season of entry and chronotype, together with the discovery results showed genome-wide significance. RNA interference knockdown experiments of the conserved ABCC9 homologue in Drosophila neurons renders flies sleepless during the first 3 h of the night. ABCC9 encodes an ATP-sensitive potassium channel subunit (SUR2), serving as a sensor of intracellular energy metabolism.

Croatian medical students see academic dishonesty as an acceptable behaviour: a cross-sectional multicampus study

AIM

To provide insights into the students' attitude towards academic integrity and their perspective of academic honesty at Croatian medical schools.

METHODS

A cross-sectional study using an anonymous questionnaire containing 29 questions on frequency of cheating, perceived seriousness of cheating, perceptions on integrity atmosphere, cheating behaviour of peers and on willingness to report misconduct. Participants were third-year (preclinical) and fifth-year (clinical) students from all four Croatian Schools of Medicine. Outcome measures were descriptive statistical correlates and differences in students' self-reported educational dishonesty, perceptions of cheating behaviour and medical school integrity atmosphere.

RESULTS

Of the 1074 students enrolled in the third and fifth year, 662 (62%) completed the questionnaire. A large proportion of the students (97%) admitted using some method of cheating and 78% admitted engaging in at least one form of misconduct. About 50% had a lenient attitude towards six acts of academic dishonesty. Only 2% reported another student for cheating. Risk factors for cheating were strongly correlated with students' perceptions of peer cheating behaviour, peer approval of cheating, low perception of seriousness of cheating and inappropriate severity level of exams and teaching materials.

CONCLUSIONS

Cheating is prevalent in Croatian medical schools and academic dishonesty is seen as acceptable behaviour among numerous future Croatian doctors.

[Risk for sleep apnea syndrome and excessive daily sleepiness in chronic hemodialysis patients]

Sleeping disorders are common among chronic hemodialysis (HD) patients and obstructive sleep apnea (OSA) syndrome frequency is often underestimated.

AIM

fo examine the risk for OSA in chronic HD patients.

METHOD

The study included all chronic HD patients in University Hospital Osijek (N=180), mean age 63 years, 92 men. They were treated by maintenance HD for median 3 years (0-26). The patients fulfilled the Croatian version of STOP and Epworth Sleepiness Scale (ESS) questionnaires.

RESULTS

According to the STOP questionnaire, 80.6% of the patients have the risk for OSA, with significant difference in gender distribution (P=0.002). 27.2% of the patients declared excessive daytime sleepiness. The patients at risk for OSA have significantly more expressed excessive daytime sleepiness in comparison with the patients without the risk (P=0.017). 55% of the patients were obese, without more expressed excessive daytime sleepiness. Mean daytime sleepiness score was 4.41. According to the ROC analysis, the cutoff score for the risk for OSA assessed by STOP questionnaire at ESS was 2, with sensitivity 71% and specificity 57,1% (AUC 0.644, P=0.003). OSA related risks and comorbidities were present in the forms of snoring in 43,3%, excessive daytime sleepiness in 77,2%. observed apnea during sleep in 6.7%, arterial hypertension in 90%, diabetes mellitus in 6.7%, asthma in 7.8%, depression in 10.6% and gastroesophageal reflux in 38% patients.

DISCUSSION

Chronic HD patients in the University Hospital Osijek have high risk for OSA, with significant gender related difference more frequent in women). Epidemiologic studies of OSA to date showed higher prevalence in men. Increase in the global prevalence of obesity goes along with OSA prevalence. Our study did not find obesity to be a risk for OSA. Furthermore, our study showed lower value of cut-off score in excessive daytime sleepiness as the risk for OSA according to the STOP questionnaire than was officially recommended for ESS. Mean daytime sleepiness score determined by our study of 4.41 was obviously lower than in several other studies on thc patients diagnosed with sleeping disorders. The survey performed in the Centre for Sleeping Medicine in Split proposed ethnicity, life habits, sociologic and cultural factors as reasons for such broad variations in the results of mean daytime sleepiness obtained in their and other authors' studies Both the STOP questionnaire and the ESS can successfully discriminate healthy from OSA subjects. However, STOP questionnaire showed to be better predictor for OSA than ESS in the Centre for Sleeping Medicine in the Split survey. While our study found significantly less patients with excessive daytime sleepiness (according to the results of ESS) than the proportion of the patients at risk for OSA by STOP questionnaire (with significantly higher daytime sleepiness in the patients at risk or OSA), polysomnography should be performed in the patients at risk and the results compared afterwards. Objective measurements are needed, but this does not change the fact that there is still a need for studies aimed to find clinical predictors for OSA for different countries with distinct life habits and different languages. Therefore, standardized questionnaire version is necessary.

CONCLUSION

The patients on chronic HD in University Hospital Centre Osijek had high frequency of risk for sleep apnea syndrome, especially women. The risk related risks and comorbidities in those patients were also common. Excessive daytime sleepiness was significantly higher in those with risk for OSA and the risk related cut-off score for excessive daily sleepiness was lower than the official for ESS. Polysomnography should be performed in the patients at risk also to assess specificity of STOP and ESS questionnaires in the patients at maintenance HD.

Acute intermittent hypoxia induces phrenic long-term facilitation which is modulated by 5-HT1A receptor in the caudal raphe region of the rat

Obstructive sleep apnoea (OSA) is characterized by periods of upper airway collapse accompanied by repeated episodes of hypoxia. In experimental animals repeated bouts of hypoxia may evoke sustained augmentation of phrenic nerve activity, known as phrenic long-term facilitation (pLTF). This form of physiological compensation might contribute to stable breathing, minimizing the occurrence of apnoeas and/or hypopnoeas during sleep in patients with OSA. Serotonin (5-HT) has been shown to modulate respiratory neuronal activity, possibly via projections originating in the raphe nuclei. Our model focuses on the effects of 5-HT1A receptors blockade by selective antagonist WAY-100635 into the caudal raphe region on phrenic long-term facilitation after exposure to acute intermittent hypoxia (AIH) episodes. Adult, male, urethane-anaesthetized, vagotomized, paralyzed and mechanically ventilated Sprague-Dawley rats were exposed to AIH protocol. Experimental group received microinjection of WAY-100635 into the caudal raphe nucleus, whereas the control group received saline into the same site. Peak phrenic nerve activity and respiratory rhythm parameters were analysed during five hypoxic episodes, as well as at 15, 30 and 60 min after the end of hypoxias. In the control group, 1 h post-hypoxia pLTF was developed. Microinjections of selective 5-HT1A receptor antagonist WAY-100635 into the raphe nuclei prior to the AIH protocol prevented induction of pLTF. These results suggest that 5-HT1A receptor activation at supraspinal level is important for induction of pLTF, which is suggested to be an important respiratory neuroplasticity model in animal studies that possibly correlates with OSA in humans.

Blood pressure dipping and salivary cortisol as markers of fatigue and sleep deprivation in staff anesthesiologists

Anesthesiologists often work extended duty shifts that result in acute and chronic sleep loss and circadian disruption. Stress caused by sleep deprivation, together with excessive workload could contribute to acute increases in blood pressure (BP) and sympathetic nervous system activity. Non-dipping pattern of BP is considered an additional risk factor for cardiovascular events and target organ damage. We hypothesized that there would be significant changes of cardiovascular parameters when comparing work on call during the 24-hour in-hospital shift (24-HD) versus ordinary working day (8-HD) combined with changes of dipping pattern and altered diurnal cortisol secretion, measured by salivary cortisol (SC). Following local Medical Ethics Committee approval, 12 out of 36 staff anesthesiologists (8 male, 4 female), 33-61 years old, participated in this study. Ambulatory BP monitor was used for noninvasive 24-hour ambulatory BP and heart rate (HR) monitoring. Each participant was monitored continuously during the 8-HD, as well as during the 24-HD. Saliva for analysis of cortisol levels was collected six times a day (at 8 am, 11 am, 2 pm, 5pm, 8pm, and 11 pm) both during 8-HD and on 24-HD. There was a significant decrease in number of diastolic dippers on call vs. diastolic dippers on ordinary working day (4/12 vs. 10/12, p=0.036), and non significant decrease of systolic dippers (3/12 vs. 7/12, p =0.214). There were no significant differences in SC values between 8-HD and 24-HD at all observed time points. However, the SC values measured during the night were markedly elevated on both days compared with reference values and the shapes of SC curves were altered. The lack of diastolic BP dipping could be more sensitive indicator of stress among staff anesthesiologists than systolic BP dipping. The shape of SC diurnal curve in terms of elevated night values could be another indicator of their chronic fatigue.

Succinylcholine use in adult anesthesia - A multinational questionnaire survey

There are no definitive evidence based standards regarding use of succinylcholine (SCh) for anesthesia induction. However, there is a global trend toward eliminating SCh not only in elective, but also in emergency surgery in adults. The aim of the study was to survey the use of SCh in adult elective and emergency anesthesia practice in several European countries and the United States by questionnaire. One hundred and seventy anesthesiologists out of 201 possible, from six institutions in five countries (Croatia, Bosnia and Herzegovina, Hungary, United Kingdom, and the United States) anonymously completed the questionnaire about their use of SCh. The questionnaire was structured to assess the respondents': frequency of use of SCh in adult surgery (elective and emergency), reasons for use or rejection of SCh, positive and negative attributes of SCh, and observed side effects in their practice. Differences in use were tested using X2-test when appropriate. There was a significant difference in the use of SCh between countries for elective surgery with the lower use in UK and Hungary (chi2=45.8, p <0.001). One hundred and seventeen (69%) use it regularly. In emergency surgery 165 (97%) anesthesiologists use it without any significant difference among countries (chi2=2.13, p<0.711). The top indications for SCh use were anticipated difficult intubation/ventilation (74%), caesarean section (54%), and obesity and/or hiatus hernia (49%). The top reasons against SCh use were adequate substitutes (87%), fear of arrhythmias (45%), and anaphylaxis (19%). The most desirable reported drug features were: rapid onset (88%), short duration (64%), and effective relaxation (61%). Forty-six per cent of the surveyed anesthesiologists stated they had never experienced a complication with its use. The most frequently reported side effects were myalgias (47%), bradycardias (42%), and prolonged blockade (39%). Allergic reactions were reported by 13%, and asystole by 12% of physicians. From our survey it is possible to conclude that succinylcholine is still regularly used, at least by surveyed anesthesiologists in Europe and USA, in adult anesthesia practice, especially in elective surgery for which it may be least suited. This reflects the discrepancies between the international guidelines for the use of SCh and the clinical practice of many anesthesiologists in different countries. The regional differences in SCh usage may be considered through anesthesia cultures and practice variations depending on country.

Vitiligo and glaucoma - an association or a coincidence? A pilot study

Our aim was to draw attention of clinicians, dermatovenereologists and ophthalmologists to the possible association of vitiligo and ocular findings characteristic of primary open angle glaucoma (POAG). According to our clinical experience, POAG is relatively often diagnosed or previously diagnosed in patients treated for vitiligo. We found no literature report directly connecting vitiligo and POAG. The articles mentioning glaucoma, i.e. increased intraocular pressure (IOP), are mainly based on secondary type of glaucoma as a direct consequence of vitiligo treated by corticosteroids. On the other hand, there is a substantial number of articles elaborating the association of vitiligo with ocular findings in known clinical syndromes. During a 2-year period, from May 2007 to May 2009, 42 patients with vitiligo were examined at University Department of Dermatology and Venereology and referred for previously appointed ophthalmologic examination at University Department of Ophthalmology, Split University Hospital Center. All patients with vitiligo underwent complete ophthalmologic examination including visual field analysis, in order to treat and follow up or diagnose newly discovered POAG. Of 42 patients with vitiligo suspect of glaucoma, POAG was confirmed in 24 (57%) patients. Age median of all vitiligo patients was 56 (range 19-82) years. In patients with vitiligo and glaucoma, the duration of vitiligo was twofold that recorded in patients with vitiligo alone, the difference being statistically significant (z=3.3; P<0.001). The risk of developing glaucoma in vitiligo patients was 4.4-fold in >56 age group versus <56 age group and 3.5-fold in patients with >13 year versus patients with <13 year duration of vitiligo. Multivariate logistic regression for glaucoma development according to vitiligo duration (< or =13 years vs. > or =13 years) and patient age (< or =56 years vs. > or =56 years) pointed to the association of glaucoma development and age and yielded a 92% probability for the association of glaucoma development and vitiligo duration. Therefore, we believe that patients treated for vitiligo should regularly undergo complete ophthalmologic examination with special attention paid to POAG irrespective of age, sex, severity, localization and duration of the disease. Although performed in a relatively small sample and over short period of time, the results of this pilot study demonstrated that this association was not accidental. Additional studies in a greater sample of vitiligo patients and POAG are expected to provide definitive answers and conclusion on the association of these two diseases.

[Succinylcholine use by anesthesiologists in Croatia--is it really abandoned?]

The aim was to establish the prevalence of succinylcholine use among Croatian anesthesiologists in adult elective and emergency surgery, as well as in pediatric surgery, regarding gender, position, working place, and working experience of physicians. The anesthesiologists were expected to express their personal opinions regarding the drug, as well as experienced side effects in their own clinical practice. A total of 125 anesthesiologists (out of 590 in Croatia) from both university and county hospitals in Croatia anonymously filled out the questionnaire regarding the use of succinylcholine (Appendix 1). The questionnaire was structured to assess the use of succinylcholine in adult elective and emergency surgery, and in pediatric anesthesia, to obtain the reasons for the preference or rejection of succinylcholine, and information about observed side effects. The differences in use regarding gender, position, working place, and working experience were tested using chi-squared test and Fisher's exact test. p < 0.05 was considered significant. Vast majority (approximately 70%) of anesthesiologists in Croatia still use succinylcholine. The percentages of anesthesiologists that never use succinylcholine in adult elective, adult emergency and pediatric surgery were 20%, 6%, and 31%, respectively. There were no significant differences in the use of succinylcholine regarding position, working place, and working experience, but male anesthesiologists used it less frequently in pediatric anesthesia compared with their female colleagues (chi2 = 5.08; p = 0.02). Forty-two per cent never experienced a complication from the drug use. The most frequently reported side effects were bradycardias (67%) and myalgias (54%), followed by prolonged blockade (33%), and allergy (33%). Asystole was reported by 10% of the respondents. In conclusion, succinylcholine is still widely used by anesthesiologists in Croatia. The majority of surveyed physicians were aware of its possible dangerous adverse effects, but still use it in certain situations. Therefore, indications and contraindications for its use deserve expert consensus guidelines based on the available scientific evidence.