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Papers by Abdulghani Sankari

Individuals living with spinal cord injury or disease (SCI/D) are at increased risk for sleep-dis... more Individuals living with spinal cord injury or disease (SCI/D) are at increased risk for sleep-disordered breathing (SDB), with a prevalence that is three-to fourfold higher than the general population. The main features of SDB, including intermittent hypoxemia and sleep fragmentation, have been linked to adverse cardiovascular outcomes including nocturnal hypertension in patients with SCI/D. The relationship between SDB and SCI/D may be multifactorial in nature given that level and completeness of injury can affect central control of respiration and upper airway collapsibility differently, promoting central and/or obstructive types of SDB. Despite the strong association between SDB and SCI/D, access to diagnosis and management remains limited. This review explores the role of SCI/D in the pathogenesis of SDB, poor sleep quality, the barriers in diagnosing and managing SDB in SCI/D, and the alternative approaches and future directions in the treatment of SDB, such as novel pharmacologic and nonpharmacologic treatments. CHEST 2019; 155(2):438-445 KEY WORDS: central sleep apnea; continuous positive airway pressure; multiple sclerosis; OSA; sleep apnea; sleep-disordered breathing; spinal cord injury; tetraplegia Sleep disturbances, including sleep-disordered breathing (SDB), are common albeit underrecognized in individuals with spinal cord injury or disease (SCI/D). 1,2 This review explores the relationship between SCI/D and SDB, discusses the pathogenesis of SDB after acute and chronic SCI/D, outlines a diagnostic and management approach, and identifies barriers to optimal management of this condition. Epidemiology of SDB in Patients With SCI/D Improved acute care after traumatic injury has resulted in increased survival for patients with SCI/D and increased likelihood of experiencing chronic diseases common in ABBREVIATIONS: CSA = central sleep apnea; HSAT = home sleep apnea testing; PAP = positive airway pressure; Pcrit = critical closing pressure; SCI = spinal cord injury; SCI/D = spinal cord injury or disease; SDB = sleep-disordered breathing

rationale Sleep-disordered breathing (SDB) is strongly linked to adverse cardiovascular outcomes ... more rationale Sleep-disordered breathing (SDB) is strongly linked to adverse cardiovascular outcomes (cardiovascular diseases (CVD)). Whether heart rate changes measured by nocturnal R-R interval (RRI) dips (RRI dip index (RRDI)) adversely affect the CVD outcomes is unknown. Objectives To test whether nocturnal RRDI predicts CVD incidence and mortality in the Wisconsin Sleep Cohort study (WSCS), independent of the known effects of SDB on beat-to-beat variability. Methods The study analysed electrocardiograph obtained from polysomnography study to assess the nocturnal total RRDI (the number of RRI dips divided by the total recording time) and sleep RRDI (the number of RRI dips divided by total sleep time). A composite CVD risk as a function of total and sleep RRDI was estimated by Cox proportional hazards in the WSCS. results The study sample consisted of 569 participants from the WSCS with no prior CVD at baseline were followed up for up to 15 years. Nocturnal total RRDI (10-unit change) was associated with composite CVD event(s) (HR, 1.24 per 10-unit increment in RRDI (95% CI 1.10 to 1.39), p<0.001). After adjusting for demographic factors (age 58±8 years old; 53% male; and body mass index 31±7 kg/m 2), and apnoea-hypopnoea index (AHI 4%), individuals with highest total nocturnal RRDI category (≥28 vs<15 dips/hour) had a significant HR for increased incidence of CVD and mortality of 7.4(95% CI 1.97 to 27.7), p=0.003). Sleep RRDI was significantly associated with new-onset CVD event(s) (HR, 1.21 per 10-unit increment in RRDI (95% CI 1.09 to 1.35), p<0.001) which remained significant after adjusting for demographic factors, AHI 4%, hypoxemia and other comorbidities. Conclusion Increased nocturnal RRDI predicts cardiovascular mortality and morbidity, independent of the known effects of SDB on beat-to-beat variability. The frequency of RRDI is higher in men than in women, and is significantly associated with new-onset CVD event(s) in men but not in women. IntrOduCtIOn Sleep-disordered breathing (SDB) is a disorder characterised by the occurrence of recurrent episodes of apnoea and hypo-pnoea, resulting in a cascade of physiological responses including hypoxemia,

Rizwan A, Sankari A, Bascom AT, Vaughan S, Badr MS. Nocturnal swallowing and arousal threshold in... more Rizwan A, Sankari A, Bascom AT, Vaughan S, Badr MS. Nocturnal swallowing and arousal threshold in individuals with chronic spinal cord injury.Respiratory complications are potential causes of death in patients with spinal cord injury (SCI). Nocturnal swallowing could be related to transient arousals and could lead to fragmented sleep in SCI patients. However, the impact of nocturnal swallowing on breathing and sleep physiology in SCI is unknown. The objectives of this study were 1) to determine whether nocturnal swallowing is more common in SCI than in able-bodied (AB) subjects, 2) to determine the role of nocturnal swallowing on arousal threshold (ArTh) in SCI individuals with sleep-disordered breathing (SDB), and 3) to determine the effect of continuous positive airway pressure (CPAP) treatment on nocturnal swallowing. A total of 16 SCI and 13 AB subjects with SDB completed in-laboratory polysomnography with a pharyngeal catheter. A swallowing event (SW) was defined as a positive spike in pharyn-geal pressure and was used to calculate the swallow index (SI) defined as a number of SW/total sleep time. Each SW was assessed for a relationship to the sleep stages and respiratory cycle phases, and associated arousals and ArTh were calculated. SI was higher in the SCI group compared with AB subjects during wake and different sleep stages (P 0.05). SWs were found to be significantly higher in the late expiratory phase in the group with SCI compared with the other respiratory phases and were eliminated by CPAP (P 0.05). ArTh for the subjects with SCI was significantly lower (P 0.05) compared with the AB subjects. Nocturnal swallowing is more common in SCI than in AB individuals who have SDB, particularly during the expiratory phase. The ArTh is significantly lower in SCI (indicat-ing increased arousal propensity), which may contribute to the mechanism of sleep disturbances in SCI.

Respiratory complications in patients with spinal cord injury (SCI) are common and can have a neg... more Respiratory complications in patients with spinal cord injury (SCI) are common and can have a negative impact on the quality of patients' lives. Previously, we found that intradiaphragmatic administration of the nanoconjugate-bound A 1 adenosine receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) induced recovery of diaphragm function following SCI in rats. When administered immediately following the injury, recovery was observed as early as 3 days following SCI and it persisted until the end of the study, 28 days after the drug delivery. The recovery was observed using diaphragmatic electromyography (EMG) as well as phrenic nerve recordings; both of which were conducted under anesthetized conditions. Confounding effects of anesthetic may make data interpretation complex in terms of the impact on overall ventilatory function and clinical relevance. The objective of the present study was to test the hypothesis that intradiaphragmatic administration of nanoconjugate-bound DPCPX, enhances recovery of ventilation following SCI in the unanesthetized rat. To that end, Sprague-Dawley rats underwent C2 spinal cord hemisection (C2Hx) on day 0 and received either: (i) 0.15 μg/kg of nanoconjugate-bound DPCPX or (ii) vehicle control (50 μl distilled water). To assess ventilation, unrestrained whole body plethysmography (WBP) was performed on day 0 (immediately before the surgery) and 3, 7, 14, 21 and 28 days following the SCI. Frequency, tidal volume, and minute ventilation data were analyzed in two minute bins while the animal was calm and awake. We found that a single administration of the nanoconjugate-bound A 1 adenosine receptor antagonist facilitated recovery of tidal volume and minute ventilation following SCI. Furthermore, the treatment attenuated SCI-associated increases in respiratory frequency. Taken together, this study suggests that the previously observed DPCPX nanoconjugate-induced recovery in diaphragmatic and phrenic motor outputs may translate to a clinically meaningful improvement in ventilatory function in patients with SCI.

Rationale: Current scoring criteria of non-apneic events (ie, hypopnea) require the presence of o... more Rationale: Current scoring criteria of non-apneic events (ie, hypopnea) require the presence of oxyhemoglobin desaturation and/or arousal. However, other sleep study parameters may help to identify abnormal respiratory events (REs) and assist in making more accurate diagnosis. Objectives: To investigate whether non-apneic REs without desaturation or cortical arousal are associated with respiratory and cardiac consequences. Methods: Thirteen participants with sleep disturbances (snoring and/or excessive day time sleepiness), were screened using attended in laboratory pol-ysomnography (PSG) while monitoring pressure and airflow via a nasal mask with an attached pneumotach. To separate the contribution of the upper airway resistance (R UA) and total pulmonary resistance (R L), supraglottic and esophageal pressures were measured using Millar pressure catheters. R L and R UA were calculated during baseline and hypopneas. R L was defined as the resistive pressure divided by the maximal flow during inspiration and expiration. Hypopnea was defined 30% decrease in flow with 3% desaturation and/or cortical arousal. REs was defined as 30% decrease in the flow without desaturation and/or cortical arousal. In eight subjects continuous positive airway pressure (CPAP) was titrated to optimal pressure. R-R interval (RRI) was defined as consecutive beat-to-beat intervals on single lead electrocardiograph (ECG) during baseline, RE/hypopnea and on optimal CPAP. Results: REs associated with increased expiratory R UA (14.6 ± 11.3 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), and increased expiratory R L relative to baseline (29.2 ± 14.6 vs. 20.9 ± 11.0 and 23.7 ± 12.1 vs. 14.3 ± 5.6 cmH 2 O L −1 s −1 during inspiration and expiration, respectively; p < .05). RRI decreased significantly following RE and hypopnea relative to baseline (804.8 ± 33.1 vs. 806.4 ± 36.3 vs. 934.3 ± 45.8 ms; p < .05). Optimal CPAP decreased expiratory R UA (4.0 ± 2.5 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), decreased inspiratory R L (12.6 ± 14.1 vs. 7.5 ± 4.5 cmH 2 O L −1 s −1 ; p < .05), and allowed RRI to return to baseline (p < .05). RRI dips index was an independent predictor of sleep-disordered breathing (SDB) when non-apneic REs were accounted for in symptomatic patients (p < .05). Conclusions: Non-apneic REs without cortical arousal or desaturation are associated with significant respiratory and heart rate changes. Optimal CPAP and the reduction of resistive load are associated with the normalization of heart rate indicating potential clinical benefit.

Sleep-disordered breathing (SDB) is prevalent in individuals with chronic spinal cord injury (SCI... more Sleep-disordered breathing (SDB) is prevalent in individuals with chronic spinal cord injury (SCI), but the exact mechanism is unknown. The aim of this study was to investigate whether peripheral chemoreceptors activity is enhanced in individuals with chronic SCI compared to abled-bodied control subjects using CO 2 and O 2 chemical tests. In protocol (1) 30 subjects (8 cervi-cal [cSCI], 7 thoracic [tSCI] and 15 able-bodied [AB]) were studied to determine the ventilatory response to hyperoxia during wakefulness in the supine position. In protocol (2) 24 subjects (6 cSCI, 6 tSCI, and 12 AB subjects) were studied to determine the ventilatory response to a single breath of CO 2 (SBCO 2). The chemoreflex response to SBCO 2 was calculated as ΔV E /ΔCO 2 (L/min/mmHg). The ventilatory response to hyperoxia was defined as the % change in V T following acute hyperoxia compared to preceding baseline. During hyperoxia SCI subjects had a significant decrease in V T and V E (63.4 AE 21.7% and 63.1 AE 23.0% baseline, respectively, P < 0.05) compared to AB (V T : 87.1 AE 14.3% and V E : 91.38 AE 15.1% baseline, respectively, P < 0.05). There was no significant difference between cSCI and tSCI in the V T or V E during hyperoxia (P = NS). There was no significant correlation between AHI and V E % baseline (r = À0.28) in SCI and AB (n = 30). SCI participants had a greater ventilatory response to an SBCO 2 than AB (0.78 AE 0.42 L/min/mmHg vs. 0.26 AE 0.10 L/min/mmHg, respectively, P < 0.05). Peripheral ventilatory chemoresponsiveness is elevated in individuals with chronic SCI compared to able-bodied individuals.

Sankari A, Bascom AT, Riehani A, Badr MS. Tetraplegia is associated with enhanced peripheral chem... more Sankari A, Bascom AT, Riehani A, Badr MS. Tetraplegia is associated with enhanced peripheral chemoreflex sensitivity and ventila-tory long-term facilitation. Cardiorespiratory plasticity induced by acute intermittent hypoxia (AIH) may contribute to recovery following spinal cord injury (SCI). We hypothesized that patients with cervical SCI would demonstrate higher minute ventilation (V ˙ E) following AIH compared with subjects with thoracic SCI and able-bodied subjects who served as controls. Twenty-four volunteers (8 with cervical SCI, 8 with thoracic SCI, and 8 able-bodied) underwent an AIH protocol during wakefulness. Each subject experienced 15 episodes of isocapnic hypoxia using mixed gases of 100% nitrogen (N 2), 8% O2, and 40% CO2 to achieve oxygen saturation 90% followed by room air (RA). Measurements were obtained before, during, and 40 min after AIH to obtain ventilation and heart rate variability data [R-R interval (RRI) and low-frequency/ high-frequency power (LF/HF)]. AIH results were compared with those of sham studies conducted in RA during the same time period. Individuals with cervical SCI had higher V ˙ E after AIH compared with able-bodied controls (117.9 23.2% vs. 97.9 11.2%, P 0.05). RRI decreased during hypoxia in all individuals (those with cervical SCI, from 1,009.3 65.0 ms to 750.2 65.0 ms; those with thoracic SCI, from 945.2 65.0 ms to 674.9 65.0 ms; and those who were able-bodied, from 949 75.0 to 682.2 69.5 ms; P 0.05). LH/HF increased during recovery in individuals with thoracic SCI and those who were able-bodied (0.54 0.22 vs. 1.34 0.22 and 0.67 0.23 vs. 1.82 0.23, respectively; P 0.05) but remained unchanged in the group with cervical SCI. Our conclusion is that patients with cervical SCI demonstrate ventilatory long-term facilitation following AIH compared with able-bodied controls. Heart rate responses to hypoxia are acutely present in patients with cervical SCI but are absent during posthypoxic recovery. hypoxia; long-term facilitation; acute intermittent hypoxia; plasticity; cardiac autonomic response; spinal cord injury SPINAL CORD INJURY (SCI) IS the second most common cause of paralysis, affecting more than one million individuals in the United States alone (44). Unfortunately, life expectancy in patients with SCI remains less than the general population, despite improved critical care, targeted rehabilitation, and longer short-term survival (53). Cardiac and respiratory disorders are the two leading causes of morbidity and mortality in patients with SCI (18). In fact, patients with SCI experience repetitive episodes of hypoxia during sleep due to impaired cough, decreased lung volume, impaired chest wall mechanics (16, 49), and higher prevalence of sleep-disordered breathing (SDB) than the general population (47, 48, 52). The ensuing, intermittent hypoxia can induce sensory long-term facilitation (LTF), which manifests by increased peripheral chemo-responsiveness , enhanced LTF following acute intermittent hypoxia (AIH) (41), and increased propensity to central apnea in a similar fashion to that of patients with obstructive sleep apnea (11). Intermittent hypoxia-induced neural plasticity may play an important role in motor and sensory recovery following SCI (39). Likewise, cardiac and respiratory plasticity induced by AIH may contribute to respiratory recovery following SCI. Tester et al. (56) demonstrated ventilatory LTF in patients with SCI under hypercapnic conditions. However, the presence of hypercapnia during the recovery period may have amplified the ventilatory response. Furthermore, the study did not assess the effect of SCI level on the magnitude of ventilatory LTF, nor did it assess the associated cardiac responses to hypoxia. The purpose of this study was to determine whether LTF evoked by AIH is dependent on the level of SCI and is coupled by cardiac autonomic modulations. Patients with tetraplegia are at risk for developing hypocapnic apneic threshold, indicating increased breathing instability, compared with individuals with thoracic SCI and those who are able-bodied (48). We hypothesized that patients with cervical SCI would demonstrate higher V ˙ E following AIH compared with individuals with thoracic SCI and subjects who served as able-bodied controls. Results of this study have been previously reported in the form of abstracts (8).

We read with great interest the article by Goh et al. 1 on ambulatory blood pressure (BP) monitor... more We read with great interest the article by Goh et al. 1 on ambulatory blood pressure (BP) monitoring and diurnal urine production in 44 tetraplegic and 10 paraplegic spinal cord injury (SCI) patients. Data were obtained retrospectively to quantify diurnal BP patterns including nocturnal hypertension and to measure diurnal urine production. The authors concluded that 'ambulatory BP monitoring in patients with SCI and clinically significant BP disorders detected a high incidence of reversed dipping and nocturnal hypertension.' In addition, the authors speculated that 'elevated nocturnal BP may contribute to nocturnal diuresis that might cause relative volume depletion and thereby contribute to daytime orthostatic hypotension.' After reading these conclusions and on the basis of available evidence of very high prevalence of sleep-disordered breathing (SDB) and cardiovascular morbidities in SCI patients, we felt compelled to write this letter. Our major concern is that the authors do not report information on sleep-related disorders as contributors to the mechanism of nocturnal hypertension in SCI patients. Further, new data (summarized below) suggest that under-recognition of SDB could contribute to the increased prevalence of hypertension and cardiovascular disorders in this population of patients. In fact, more than half of patients with SCI are obese or overweight, leading to an increased risk for both SDB and cardiac diseases. 2 Our group has been studying SDB among SCI patients, and, we have found that SDB, defined by the apnea–hypopnea index ⩾ 5 events per hour, was present in 77% of chronic SCI patients, with rates higher among those with cervical compared with thoracic injuries (93% vs 55%, respectively, Po0.05). 3 One in four cervical SCI had Cheyne–Stokes respiration pattern during their overnight laboratory sleep study, and one in five had hypertension or cardiac disease. Furthermore, nearly all patients had poor sleep quality and daytime sleepiness or fatigue as measured by the Pittsburgh Sleep Quality Index, the Fatigue Severity Scale and the Epworth Sleepiness Scale. In the manuscript, the authors did not report information on whether or not patients had SDB or whether other cardiovascular comorbidities were present. We also are interested in the rates of diagnosis of SDB (obstructive sleep apnea and/or central sleep apnea) in SCI patients receiving usual clinical care, and, to that end, we reviewed medical records of patients who were included in the local Spinal Cord Injury and Disorders Outcomes database at the John D Dingell VA Medical Center. We identified a total of 168 veterans with SCI/or disorder. We found that only 37 patients (22%) were evaluated for SDB and 34 (20%) had SDB diagnosis confirmed by the sleep study, of whom only 6 patients (18%) were using the positive airway pressure (PAP) therapy. Moreover , 89 (53%) of SCI veterans had hypertension and 26 (16%) had cardiovascular disease (including one or more of the following diagnoses: myocardial infarction, coronary artery disease and/or chronic heart failure), which may be caused or exacerbated by untreated SDB. The strong relationship between untreated SDB and nocturnal hypertension had been repeatedly confirmed in able-bodied individuals with SDB. Ambulatory BP monitoring allows accurate assessment of circadian BP changes, which can identify a blunted nocturnal decline in BP and indicate the possible secondary cause of hypertension, such as sleep apnea. Specifically, the non-dipping BP phenomenon measured by ambulatory BP monitoring was found in untreated patients with SDB and was associated with poor outcome. Therefore, on the basis of above findings, it is unfortunate that in this manuscript the authors did not assess the presence of SDB in these patients. We thank Goh et al. for their efforts to address these important problems in SCI patients. However, awareness of sleep disorders as potentially treatable risk factors for nocturnal hypertension and altered diurnal ambulatory BP is critical to achieving the best outcomes for SCI patients. In this vulnerable population, the lack of awareness and treatment of SDB among SCI patients may represent a form of healthcare disparity for the disabled. The consequences of untreated SDB and associated cardiovascular disorders are severe and could contribute to the higher mortality rate in this population. We therefore recommend consideration of SDB as a possible underlying variable explaining the findings reported in this paper. CONFLICT OF INTEREST The authors declare no conflict of interest. ACKNOWLEDGEMENTS

A high prevalence of sleep-disordered breathing (SDB) after spinal cord injury (SCI) has been rep... more A high prevalence of sleep-disordered breathing (SDB) after spinal cord injury (SCI) has been reported in the literature; however, the underlying mechanisms are not well understood. We sought to determine the effect of the withdrawal of the wakefulness drive to breathe on the degree of hypoventilation in SCI patients and able-bodied controls. We studied 18 subjects with chronic cervical and thoracic SCI (10 cervical, 8 thoracic SCI; 11 males; age 42.4 AE 17.1 years; body mass index 26.3 AE 4.8 kg/m 2) and 17 matched able-bodied subjects. Subjects underwent polysomnography, which included quantitative measurement of ventilation, timing, and upper airway resistance (R UA) on a breath-by-breath basis during transitions from wake to stage N1 sleep. Compared to able-bodied controls, SCI subjects had a significantly greater reduction in tidal volume during the transition from wake to N1 sleep (from 0.51 AE 0.21 to 0.32 AE 0.10 L vs. 0.47 AE 0.13 to 0.43 AE 0.12 L; respectively, P < 0.05). Moreover, end-tidal CO 2 and end-tidal O 2 were significantly altered from wake to sleep in SCI (38.9 AE 2.7 mmHg vs. 40.6 AE 3.4 mmHg; 94.1 AE 7.1 mmHg vs. 91.2 AE 8.3 mmHg; respectively, P < 0.05), but not in able-bodied controls (39.5 AE 3.2 mmHg vs. 39.9 AE 3.2 mmHg; 99.4 AE 5.4 mmHg vs. 98.9 AE 6.1 mmHg; respectively, P = ns). R UA was not significantly altered in either group. In conclusion, individuals with SCI experience hypoventilation at sleep onset, which cannot be explained by upper airway mechanics. Sleep onset hypoventilation may contribute to the development SDB in the SCI population.

Introduction Obesity and heart failure are strongly associated with sleep-disordered breathing (S... more Introduction Obesity and heart failure are strongly associated with sleep-disordered breathing (SDB). However, the determinants of cardiac dysfunction in patients with SDB are not known. Methods We studied 90 patients suspected of having SDB (66 % women and 67 % black), age 50.4±13.4 years and body mass index (BMI) 38.6±9.8 kg/m 2. Apnea–hypopnea index (AHI) and nadir pulse oximetry (SpO 2) were determined by polysomnography recordings. Left atrial (LA) diameter and left ventricular posterior wall (LVPW) thickness were determined by echocardiography. Patients who had EF<50 %, estimated right ventricular systolic pressure >45 mmHg or valvular heart disease were excluded. Results Univariate analysis revealed a positive correlation between LA diameter and each of BMI, neck circumference (NC), and AHI (coefficients, 0.28, 0.34, and 0.36, respectively ; p<0.05). Multivariable linear regression analysis revealed that BMI was the only independent predictor of LA enlargement (coefficient 0.02, p<0.05). LVPW thickness correlated with BMI, NC, and AHI (correlation coefficients were 0.43, 0.47, and 0.33, respectively; p<0.05). Multivariable linear regression analysis revealed a significant relationship between LVPW thickness and each of BMI and NC (coefficients 0.016 and 0.007, respectively; p<0.05) but not AHI. BMI and LVPW associated with nadir SpO 2 (r=−0.60, p<0.01 and r=−0.21, p=0.05; respectively), and BMI was a predictor of nadir SpO 2 during sleep (B=−0.59; CI: −0.84, −0.33; p=0.01). Conclusions Obesity can predict cardiovascular morbidity and nocturnal hypoxemia independent of the severity of the SDB. Our findings suggest the independent contribution of excess body weight on cardiac dysfunction and hypoxia in SDB patients.

Respiratory Physiology & Neurobiology, 2013

We hypothesized that administration of clonidine would decrease the hypocapnic apnoeic threshold ... more We hypothesized that administration of clonidine would decrease the hypocapnic apnoeic threshold (HAT) and widen the CO 2 reserve during non-REM sleep. Methods: Ten healthy subjects (4 females) (age 22.3 ± 3.0 years; BMI 25.5 ± 3.4 kg/m 2 ) were randomized to receive placebo or 0.1 mg/45 kg of clonidine on 2 separate nights. Ventilation and upper airway resistance were monitored during wakefulness and sleep. Two separate experiments were performed: Protocol 1 (n = 8), CO 2 reserve, HAT and HcVR were determined using non-invasive hyperventilation (NIV) to induce hypocapnia for at least 3 min; Protocol 2 (n = 6), peripheral hypocapnic ventilatory response (HcVR) was determined by NIV using short (3 breaths) hyperventilation. Results: Clonidine decreased the systolic blood pressure by 12 ± 10 mmHg but did not affect baseline ventilation or upper airway resistance during wakefulness or sleep. Protocol (1), clonidine was associated with decreased HAT relative to placebo (37.3 ± 3.3 mmHg vs. 39.7 ± 3.4 mmHg, P < 0.05), increased CO 2 reserve (−3.8 ± 1.3 mmHg vs. −2.8 ± 1.2 mmHg, P < 0.05), and decreased HcVR (1.6 ± 0.6 L/min/mmHg vs. 2.5 ± 1.3 L/min/mmHg, P < 0.05). Protocol (2), administration of clonidine did not decrease peripheral HcVR compared to placebo (0.5 ± 0.3 L/min/mmHg vs. 0.7 ± 0.3 L/min/mmHg, P = NS). Conclusion: Clonidine is associated with diminished susceptibility to hypocapnic central apnoea without significant effect on ventilation or upper airway mechanics. Reduced susceptibility to hypocapnic central apnoea is not explained by the peripheral chemoreceptor pathway. This suggests a central rather than a peripheral effect of clonidine on the susceptibility to hypocapnic central apnoea.

A42. MONITORING IN THE ICU, 2009

ABSTRACT Pusle oximetry is routinely used in the intensive care units (ICU) for continuous oxygen... more ABSTRACT Pusle oximetry is routinely used in the intensive care units (ICU) for continuous oxygenation assessment. In critically ill patients, however, when peripheral tissue is poorly perfused, the signal from the pulsatile blood flow is impaired leading to a less accurate estimate of SaO2. The purpose of this study is to examine the accuracy of pulse oximeter in ICU patients who are on mechanical ventilation in comparison to SaO2 obtained by simultaneous arterial blood gas (ABG). Secondary outcome is to examine the detrimental effect of vasopressors on the accuracy of pulse oximetry measurements. Design: Prospective observational study in tertiary care medical ICU. Measurements: pulse oximetry obtained simultaneously with ABG, vital signs, and use of vasopressors. Inclusion criteria: All adult patients aged 18 -89 yo who are admitted to intensive care unit and mechanically ventilated. Exclusion criteria: Age <18 yo, severe anemia (Hgb <8), pregnancy, Methemoglobulinemia, Carbon monoxide exposure or toxicity, and pigmented skin. SpO2 and O2 Sat from 91 mechanically ventilated patients were compared using Bland-Altman analysis. 21 patients (25%) had vasopressors during the data collection. Results: see table Results Mean Difference (%) 95%CI Upper limits of agreement (%) Lower limits of agreement (%) All (N=91) -1.9 2.3 -1.7,-2.1 2.8 -6.7 Vasopressors (N=24) -1.9 1.8 -1.5,-2.3 1.7 -5.5 No vasopressors (N=67)-1.9 2.4 -1.7, -2.1 2.9-6.7 Conclusion: Oxygen saturation can be accurately measured using pulse oximetry in mechanically ventilated patients. Vasopressors do not impair the accuracy of pulse oximetry measurements above 90%.

A68. UPPER AIRWAY AND RESPIRATORY PHYSIOLOGY, 2010

Sleep disordered breathing (SDB) is more common in males than in females. The exact mechanism for... more Sleep disordered breathing (SDB) is more common in males than in females. The exact mechanism for the gender difference is not known. Hypocapnia vs. altered ventilatory drive may play a role in the gender difference in SDB. The purpose of this investigation was to ascertain a gender difference in the effect of hypocapnic hypoxia on inspiratory and expiratory upper airway resistance (R ). Methods: 3-minute UA periods of hypocapnic hypoxia were induced in 10 normal males and females (aged 30±8 yrs) matched for BMI during stable sleep. We measured airflow using a pneumotachometer and supraglottic pressure (Psg) using a transducer-tipped catheter (Millar). R was UA measured during inspiratory and expiratory phases at peak flow. Upper airway expiratory distending pressure (ΔP ) was defined as the UA difference in Psg between nadir inspiratory and peak expiratory pressures. Inspiratory flow limitation was defined as the dissociation between pressure and flow expressed as % from all breaths analyzed. Results: See table

B72. CONSEQUENCES OF SLEEP DISORDERED BREATHING: CLINICAL ASPECTS, 2010

A68. UPPER AIRWAY AND RESPIRATORY PHYSIOLOGY, 2010

Page 1. / Thematic Poster Session / Sunday, May 16/8:15 AM-4:00 PM / Area K, A68 UPPER AIRWAY AND... more Page 1. / Thematic Poster Session / Sunday, May 16/8:15 AM-4:00 PM / Area K, A68 UPPER AIRWAY AND RESPIRATORY PHYSIOLOGY Hall G (First Level), Morial Convention Center Effect Of Neuromuscular Activity On Upper Airway Mechanics During Sleep ...

Sleep and Breathing, 2005

Titration of continuous positive airway pressure (CPAP) is performed to determine the CPAP settin... more Titration of continuous positive airway pressure (CPAP) is performed to determine the CPAP setting to prescribe for an individual patient. A prediction equation has been published that could be used to improve the success rate of CPAP titrations. The goals of this study were: (1) to test the hypothesis that the use of the prediction equation would achieve a higher rate of successful CPAP titrations; (2) to validate the equation as an accurate predictor of the prescribed CPAP setting and determine the factors that influence the accuracy of the prediction equation. A total of 224 patients underwent CPAP titration prior to using the equation, with a starting pressure of 5 cm H 2 O. A total of 192 patients underwent CPAP titration using the equation-predicted CPAP level as the starting pressure (median starting pressure of 8 cm H 2 O [interquartile range 7, 10 cm H 2 O]). The percentage of successful studies, as defined by a 50% decrease in the apnea-hypopnea index (AHI) and a final AHI ≤10 cm H 2 O, increased from 50% to 68% (p<0.001), while the number of patients who were prescribed a CPAP level that had not been tested decreased from 22% to 5% (p<0.001). The equation was not accurate in predicting the prescribed level of CPAP, with only 30.8% of the patients with a prescribed pressure ≤3 cm H 2 O of the predicted pressure. Female gender was the only predictor of a prescribed pressure ≤3 cm H 2 O from the predicted pressure (odds ratio 3.45, 95% confidence intervals 1. 67, 7.13, p<0.001). A CPAP prediction equation modestly increases the rate of successful CPAP titrations by increasing the starting pressure of the titration. The equation does not accurately predict the prescribed CPAP level, reaffirming the need for a titration study to determine the optimal prescribed level in a given patient.

Respiratory Physiology & Neurobiology, 2003

Altered chemoresponsiveness has been postulated to explain the gender difference in the incidence... more Altered chemoresponsiveness has been postulated to explain the gender difference in the incidence of sleep disordered breathing (SDB). The purpose of this investigation was to ascertain a gender difference in the effect of hypocapnic hypoxia on ventilation. Hypocapnic hypoxia was induced in stable NREM sleep for 3 min periods. In the first analysis, hypoxic ventilatory response in a steady state (SHVR) was defined as the amount of change in minute ventilation (VI) between mean room air (RA) and hypoxia divided by the change in Sa O2 between RA and hypoxia (DeltaVI/DeltaSa O2). The mean group SHVR values were 0.23+/-0.15 and 0.20+/-0.10 L/min per %SaO2, for men and women, respectively (P = ns). In the second analysis, we analyzed the decline in ventilatory parameters after the cessation of hypoxia. There was no difference in VI between the genders (men, 5.6+/-1.7 L/min vs. women, 4.9+/-1.9 L/min, P = ns). We conclude that the gender difference in SDB is not explained by a difference in the ventilatory response to hypocapnic hypoxia.

Avicenna Journal of Medicine, 2012

frequency as type-I diabetes and twice that of asthma. It is estimated from the Wisconsin cohort ... more frequency as type-I diabetes and twice that of asthma. It is estimated from the Wisconsin cohort that the prevalence of OSAHS in the United States of America is 9-24% for men and 4-9% for women who were not obese (body mass index <30 kg/m 2 ) and aged 30-60 years old. Although epidemiological data from the Arab countries are lacking, especially related to OSHAS prevalence, it is estimated that millions of patients suffer from OSAHS in the Middle East and Arab countries [ ].

Respiratory Physiology & Neurobiology, 2013

A42. MONITORING IN THE ICU, 2009

A68. UPPER AIRWAY AND RESPIRATORY PHYSIOLOGY, 2010

B72. CONSEQUENCES OF SLEEP DISORDERED BREATHING: CLINICAL ASPECTS, 2010

A68. UPPER AIRWAY AND RESPIRATORY PHYSIOLOGY, 2010

Sleep and Breathing, 2005

Respiratory Physiology & Neurobiology, 2003

Avicenna Journal of Medicine, 2012