Search

Background: Cheyne-Stokes respiration is characterized by periodic breathing that alternates with hypopnea or apnea.Objective: To describe the effect of theophylline on near-fatal Cheyne-Stokes respiration.Design: Case report.Setting: Tertiary referral center.Patient: A 48-year-old diabetic woman with a history of three cardiorespiratory arrests, a normal coronary arteriogram, normal left ventricular function, and severe Cheyne-Stokes respiration.Measurements: Oxygen saturation, intra-arterial blood pressure, central venous pressure, chest wall movement, electrocardiography, electromyography, electroencephalography, electro-oculography, minute ventilation, arterial blood gases, and serum theophylline levels.Results: After intravenous administration of 1.2 mg of theophylline at 0.6 mg/kg per hour (serum level, 5.6 microg/mL), both Cheyne-Stokes respiration and oxygen desaturation were markedly attenuated. After infusion of 2.4 mg of theophylline (serum level, 11.6 microg/mL), Cheyne-Stokes respiration resolved completely. No change was seen with placebo. Cheyne-Stokes respiration did not recur during outpatient treatment with oral theophylline.Conclusion: Theophylline may be a rapid and effective therapy for life-threatening Cheyne-Stokes respiration. [ABSTRACT FROM AUTHOR]

The objective of the study was to identify symptoms of men presenting for an outpatient urology visit that prompted referral for a Home Sleep Apnea Test (HSAT) to assess for obstructive sleep apnea (OSA) by a single provider. To assess the proportion of patients referred for the HSAT who underwent the test and, out of these patients, the proportion of men diagnosed with sleep apnea, we performed a retrospective chart review of men 18-99 years old seen by a single provider in the Department of Urology referred for an HSAT to evaluate for presenting symptoms. Patients with a prior diagnosis of OSA were excluded. Eighteen patients were identified (mean age at time of referral 51 + SD 13 years). Half of patients reported erectile dysfunction/concerns, 56% reported nocturia, 44% had been diagnosed with testosterone deficiency, and 39% reported low libido. Nearly all (89%) of patients snored, all reported fatigue, 56% were over the age of 50, 44% had a BMI >35, and 78% had hypertension. Twelve patients completed the HSAT, all of whom were diagnosed with OSA for which continuous positive airway pressure (CPAP) therapy was initiated. Men presenting with genitourinary concerns to an outpatient urology clinic may also have OSA. About half of included patients reported genitourinary concerns. Hundred percent of patients who completed their sleep study were diagnosed with OSA. Genitourinary concerns, in addition to signs and symptoms commonly associated with OSA, should prompt consideration of sleep apnea evaluation.

Adult mosquitoes were previously collected and tested for West Nile virus during an intense WNV outbreak in 2003-2004 along the Cache la Poudre River in Colorado, USA. A subset of these mosquitoes was also tested for infection with trypanosomatids using nested PCR to amplify 18S rRNA. Of the 69 pools of Culex pipiens that were screened for both pathogens, 4.3% were positive for WNV and 11.6% tested positive for trypanosomes; no pools were found to be co-infected with both pathogens. One hundred and forty-three pools of Culex tarsalis, considered to be the principal WNV vector in this area, were tested in the same manner. 7.7% were positive for WNV and 20.3% of these pools tested positive for trypanosomes. Five pools of C. tarsalis were found to be co-infected with both pathogens, which was approximately 2.2 times more frequent than would be expected if these pathogens are independent of each other. Sequencing and maximum parsimony analysis of 18S rRNA revealed that four of the isolates arise in or near clades of described avian trypanosomes, likely indicating that these are vectored pathogens between birds and mosquitoes. Unexpectedly, the majority (24/28, 86%) of our positive samples form their own separate clade within the order Trypanosomatida with 100% bootstrap support. We have identified a potential new clade of trypanosomatids that exist within important mosquito vectors and discuss the potential ecological connections between these trypanosomes, arboviruses and mosquitoes.

A dilemma can arise when attempting to distinguish a nocturnal seizure from a parasomnia because both phenomena can be characterized by a general increase in motor and autonomic activity with a transient reduction in the level of consciousness. An additional problem is that an accurate clinical diagnosis generally relies heavily on a detailed history. As sleep related disorders occur at a time when the patient is not fully cognizant, polysomnographic analysis can on occasion supplement for the intrinsic paucity of detailed history. Simultaneously, correlating the clinical and polysomnographic analysis immediately prior to, during, and following an event of interest, can be helpful in differentiating nocturnal seizures from parasomnias.

Background: The chemoreflexes are an important mechanism for regulation of both breathing and autonomic cardiovascular function. Abnormalities in chemoreflex mechanisms may be implicated in increased cardiovascular stress in patients with obstructive sleep apnea (OSA). We tested the hypothesis that chemoreflex function is altered in patients with OSA., Methods and Results: We compared ventilatory, sympathetic, heart rate, and blood pressure responses to hypoxia, hypercapnia, and the cold pressor test in 16 untreated normotensive patients with OSA and 12 normal control subjects matched for age and body mass index. Baseline muscle sympathetic nerve activity (MSNA) was higher in the patients with OSA than in the control subjects (43+/-4 versus 21+/-3 bursts per minute; P<0. 001). During hypoxia, patients with OSA had greater increases in minute ventilation (5.8+/-0.8 versus 3.2+/-0.7 L/min; P=0.02), heart rate (10+/-1 versus 7+/-1 bpm; P=0.03), and mean arterial pressure (7+/-2 versus 0+/-2 mm Hg; P=0.001) than control subjects. Despite higher ventilation and blood pressure (both of which inhibit sympathetic activity) in OSA patients, the MSNA increase during hypoxia was similar in OSA patients and control subjects. When the sympathetic-inhibitory influence of breathing was eliminated by apnea during hypoxia, the increase in MSNA in OSA patients (106+/-20%) was greater than in control subjects (52+/-23%; P=0.04). Prolongation of R-R interval with apnea during hypoxia was also greater in OSA patients (24+/-6%) than in control subjects (7+/-5%) (P=0.04). Autonomic, ventilatory, and blood pressure responses to hypercapnia and the cold pressor test in OSA patients were not different from those observed in control subjects., Conclusions: OSA is associated with a selective potentiation of autonomic, hemodynamic, and ventilatory responses to peripheral chemoreceptor activation by hypoxia.

Background: Altered cardiovascular variability is a prognostic indicator for cardiovascular events. Patients with obstructive sleep apnea (OSA) are at an increased risk for cardiovascular disease. We tested the hypothesis that OSA is accompanied by alterations in cardiovascular variability, even in the absence of overt cardiovascular disease., Methods and Results: Spectral analysis of variability of muscle sympathetic nerve activity, RR interval, and blood pressure were obtained during undisturbed supine rest in 15 patients with moderate-to-severe OSA, 18 patients with mild OSA, and 16 healthy control subjects in whom sleep disordered breathing was excluded by complete overnight polysomnography. Patients with OSA were newly diagnosed, never treated for OSA, and free of any other known diseases. Patients with moderate-to-severe OSA had shorter RR intervals (793+/-27 ms) and increased sympathetic burst frequency (49+/-4 bursts/min) compared with control subjects (947+/-42 ms; 24+/-3 bursts/min; P=0.008 and P<0.001, respectively). In these patients, total variance of RR was reduced (P=0.01) and spectral analysis of RR variability showed an increase in low frequency normalized units, a decrease in high frequency normalized units, and an increase in the ratio of low to high frequency (all P<0.05). Even though blood pressure was similar to that of the control subjects, blood pressure variance in patients with moderate-to-severe OSA was more than double the variance in control subjects (P=0.01). Patients with mild OSA also had a reduction in RR variance (P=0.02) in the absence of any significant difference in absolute RR interval. For all patients with OSA, linear regression showed a positive correlation (r=0.40; P=0.02) between sleep apnea severity and blood pressure variance., Conclusions: Cardiovascular variability is altered in patients with OSA. This alteration is evident even in the absence of hypertension, heart failure, or other disease states and may be linked to the severity of OSA. Abnormalities in cardiovascular variability may be implicated in the subsequent development of overt cardiovascular disease in patients with OSA.

Background: Obese humans are reported to have increased muscle sympathetic nerve activity (MSNA). Obstructive sleep apnea (OSA) may also be accompanied by increased MSNA. Because there is a high prevalence of OSA in obese humans, it is possible that high MSNA reported in obese subjects may in fact reflect the presence of OSA in these subjects. We tested the hypothesis that obesity, per se, in the absence of OSA, is not accompanied by increased MSNA., Methods and Results: We measured MSNA in 25 healthy normal-weight subjects and 30 healthy sedentary obese subjects. All subjects were screened by history and examination to exclude subjects with OSA or hypertension. OSA was further excluded by overnight polysomnographic studies. Despite careful screening, polysomnography revealed that 1 of 25 normal-weight subjects and 9 of 30 obese subjects had occult OSA (P=0.015). MSNA was similar in normal-weight subjects (41+/-3 bursts per 100 heartbeats) and obese subjects without sleep apnea (42+/-3 bursts per 100 heartbeats, P=0.99). MSNA in the 9 obese subjects with occult OSA was 61+/-8 bursts per 100 heartbeats, which was higher than MSNA in normal-weight subjects without sleep apnea (P=0.02) and higher than MSNA in obese subjects without sleep apnea (P=0.02)., Conclusions: Obesity alone, in the absence of OSA, is not accompanied by increased sympathetic activity to muscle blood vessels.

Background: Muscle sympathetic nerve activity (MSNA) is increased in patients with obstructive sleep apnea (OSA). We tested the hypothesis that tonic activation of excitatory chemoreceptor afferents contributes to the elevated sympathetic activity in OSA., Methods and Results: Using a double-blind, randomized, vehicle-controlled design, we examined the effects of chemoreflex deactivation (by comparing effects of breathing 100% oxygen for 15 minutes with effects of breathing room air for 15 minutes) on MSNA, heart rate, blood pressure, and minute ventilation in 14 untreated patients with OSA and in 12 normal subjects matched for age and body mass index. All control subjects underwent overnight polysomnography to exclude the existence of occult OSA. Baseline MSNA was markedly elevated in the patients with OSA compared with the control subjects (44+/-4 versus 30+/-3 bursts per minute; P=.01). In both control subjects and patients with OSA, heart rate decreased during administration of 100% oxygen but did not change during administration of room air. By contrast, both MSNA (P=.008) and mean arterial pressure (P=.02) were significantly reduced during chemoreflex deactivation by 100% oxygen only in patients with OSA but not in control subjects., Conclusions: Tonic activation of excitatory chemoreflex afferents may contribute to increased efferent sympathetic activity to muscle circulation in patients with OSA.

Aspirin (acetylsalicylic acid [ASA]) from 75 to 1,300 mg/day is an effective agent in the secondary prevention of stroke. Although no properly designed study has been performed, circumstantial evidence suggests that the favorable effect of ASA for stroke may be enhanced by higher doses. Ticlopidine is more effective than 1,300 mg/day of ASA, and clopidogrel is at least as effective as 325 mg of ASA a day; but, for various reasons, ASA at higher doses is still first choice by many. Three studies have shown no benefit of adding dipyridamole to ASA. A fourth did, but, in addition to other problems, the results are no better than those obtained by higher doses of ASA alone. ASA is an effective alternate to warfarin for patients with atrial fibrillation and contraindications to warfarin. Until a proper study has been performed, ASA is not recommended for the prevention of stroke in a low-risk asymptomatic elderly population.

Using serum biotin concentration as the indicator, a previous study reported biotin deficiency resulting from long-term anticonvulsant therapy. However, serum biotin may not be a good indicator of tissue biotin status. Using better indicators of biotin status in anticonvulsant-treated subjects, we found increased urinary excretion of biotin catabolites and 3-hydroxyisovaleric acid, an organic acid produced in greater quantities secondary to reduced activity of a biotin-dependent carboxylase. We conclude that anticonvulsant treatment led to increased biotin catabolism and probably to reduced biotin status.

We evaluated the utility of accurate clinical and electrophysiologic characterization in the diagnosis of the rhythmic movement disorder. Seven children with an age range of 1-12 years, referred for evaluation of relatively violent nocturnal behaviors, were clinically assessed during split-screen, video-polysomnographic monitoring sessions, as they experienced unusual nocturnus movements. Differential diagnoses included self-injurious waking behaviors, seizures, and parasomnias such as somnambulism (sleepwalking), pavor nocturnus (night terrors), and the rhythmic movement disorder (headbanging, bodyrocking, and legbanging). The character of movements, level of responsiveness, and electrophysiologic stage of sleep was determined during typical spells. In all the subjects experienced 37 periods of headbanging, bodyrocking, and legbanging that were strongly associated with stage 2 non-rapid eye movement sleep and K-complexes. The patients were unresponsive during and amnestic for the events. Because the differential for the rhythmic movement disorder includes a large number of disorders associated with abnormal and at times violent nocturnal movements, diagnosis can be greatly enhanced by documenting suspected nocturnal behaviors with thorough clinical assessment during split-screen, video-polysomnographic analysis.

Objective: To demonstrate the utility of accurate clinical and electroencephalographic characterization of provoked cataplexy spells in the diagnosis of narcolepsy., Methods: Four individuals, three with suspected and one with known narcolepsy, were clinically assessed during split-screen, video polysomnographic monitoring sessions after cataplectic events were induced by emotional provocation., Results: The subjects experienced a total of nine cataplectic-like events, one occurring spontaneously (sleep paralysis) in association with a hypnagogic hallucination. During all events, the patients appeared to be sleeping with polysomnographic rapid eye movement sleep patterns, but when questioned they were able to give appropriate verbal responses. The diagnosis of narcolepsy was substantiated in all cases using standard overnight polysomnograms and multiple sleep latency tests., Conclusion: The diagnosis of narcolepsy can be greatly enhanced by documenting cataplexy with thorough clinical assessment and demonstration of typical rapid eye movement sleep patterns during provoked spells in the course of polysomnographic monitoring sessions.

Blood pressure, heart rate, sympathetic nerve activity, and polysomnography were recorded during wakefulness and sleep in 10 patients with obstructive sleep apnea. Measurements were also obtained after treatment with continuous positive airway pressure (CPAP) in four patients. Awake sympathetic activity was also measured in 10 age- and sex-matched control subjects and in 5 obese subjects without a history of sleep apnea. Patients with sleep apnea had high levels of nerve activity even when awake (P < 0.001). Blood pressure and sympathetic nerve activity did not fall during any stage of sleep. Mean blood pressure was 92 +/- 4.5 mmHg when awake and reached peak levels of 116 +/- 5 and 127 +/- 7 mmHg during stage II sleep (n = 10) and rapid eye movement (REM) sleep (n = 5), respectively (P < 0.001). Sympathetic activity increased during sleep (P = 0.01) especially during stage II (133 +/- 9% above wakefulness; P = 0.006) and REM (141 +/- 13%; P = 0.007). Peak sympathetic activity (measured over the last 10 s of each apneic event) increased to 299 +/- 96% during stage II sleep and to 246 +/- 36% during REM sleep (both P < 0.001). CPAP decreased sympathetic activity and blood pressure during sleep (P < 0.03). We conclude that patients with obstructive sleep apnea have high sympathetic activity when awake, with further increases in blood pressure and sympathetic activity during sleep. These increases are attenuated by treatment with CPAP.

Objective: To polysomnographically determine, using split-screen electroencephalographic-video analysis, the cause of violent sleep-related activity in a patient whose differential diagnosis includes sleep walking (somnambulism), pavor incubus (adult night terrors), nocturnal seizures, psychogenic wandering, and rapid eye movement sleep behavior disorder., Setting: The patient was referred to the University of Iowa, Department of Neurology Sleep Disorders Center, Iowa City, from the local community to evaluate a history of violent dreams associated with injury. The subject presented with a subdural hemorrhage that was discovered with magnetic resonance imaging., Outcome: The diagnosis of rapid eye movement sleep behavior disorder was confirmed after a characteristic spell of violent behavior, with an associated dream, was captured polysomnographically.