Shrinking lung syndrome: vanishing in non-rapid eye movement sleep.

Shrinking lung syndrome is a rare complication of systemic lupus erythematosus; its impact on sleep-disordered breathing is not well understood. We describe a case of a 36-year-old female with systemic lupus erythematosus experiencing shrinking lung syndrome and frequent pain crises. We review manifestations of her disease during non-rapid eye movement (NREM) and rapid eye movement sleep. Shrinking lung syndrome with its restrictive physiology and associated diaphragmatic myopathy is expected to decrease minute ventilation during NREM and rapid eye movement sleep. Normalization of respiratory rate during NREM, as opposed to rapid eye movement and awake state, should alert clinicians to dysfunctional breathing that is suppressed in NREM when cortical breathing is overridden by involuntary breathing. Recognition of dysfunctional breathing disorders by sleep providers is important for addressing all contributors to dyspnea in patients with systemic lupus erythematosus; polysomnogram can be a valuable tool in detecting incongruent ventilation parameters that deviate from expected NREM and rapid eye movement norms and point to dysfunctional breathing disorders. Abnormalities in respiratory rate and gas exchange that improve or vanish in NREM sleep can serve as an additional diagnostic clue of dysfunctional breathing disorders. CITATION: Saleh D, Loewen A. Shrinking lung syndrome: vanishing in non-rapid eye movement sleep. J Clin Sleep Med. 2023;19(11):1975-1979.

Impact of wait times for treatment on clinical outcomes in patients with obstructive sleep apnoea: protocol for a randomised controlled trial.

Background: Obstructive sleep apnoea (OSA) is a common chronic condition that is associated with significant morbidity and economic cost. Prolonged wait times are increasingly being recognised as a barrier to diagnosis and treatment of many chronic diseases; however, no study to date has prospectively evaluated the impact of wait times on health outcomes in OSA. Objective: The purpose of this study is to determine whether treatment outcomes for individuals with OSA differ between patients managed using an expedited versus standard pathway. Methods: A pragmatic randomised controlled trial design will be used with a target sample size of 200 adults. Participants with clinically significant uncomplicated OSA will be recruited through referrals to a large tertiary care sleep centre (Calgary, AB, Canada) and randomised to either early management (within 1 month) or usual care (∼6 months) with a 1:1 allocation using a concealed computer-generated randomisation sequence. The primary outcome will be adherence to positive airway pressure (PAP) therapy at 3 months after treatment initiation. Secondary outcomes will include change in sleepiness, quality of life, patient satisfaction, and patient engagement with therapy from baseline to 3 months after PAP initiation, measured using validated questionnaires and qualitative methods. Anticipated results: This study will determine whether expedited care for OSA leads to differences in PAP adherence and/or patient-reported outcomes. More broadly, the findings of this study may improve the understanding of how wait time reductions impact health outcomes for other chronic diseases.

Study Design of the Phase 3 Sparsentan Versus Irbesartan (DUPLEX) Study in Patients With Focal Segmental Glomerulosclerosis.

INTRODUCTION: Focal segmental glomerulosclerosis (FSGS), a histologic lesion in the kidney caused by varied pathophysiological processes, leads to end-stage kidney disease in a large proportion of patients. Sparsentan is a first-in-class orally active compound combining endothelin type A (ETA) receptor blockade with angiotensin II type 1 (AT1) receptor antagonism in a single molecule. A Randomized, Multicenter, Double-Blind, Parallel, Active-Control Study of the Effects of Sparsentan, a Dual Endothelin Receptor and Angiotensin Receptor Blocker, on Renal Outcomes in Patients With Primary FSGS (DUPLEX) study evaluates the long-term antiproteinuric efficacy, nephroprotective potential, and safety profile of sparsentan compared with an AT1 receptor blocker alone in patients with FSGS. METHODS: DUPLEX is a multicenter, international, phase 3, randomized, double-blind, active-controlled study of sparsentan in patients with FSGS. Approximately 300 patients aged 8 to 75 years, inclusive (United States), and 18 to 75 years, inclusive (outside United States) will be randomized 1:1 to daily treatment with sparsentan or irbesartan. After renin-angiotensin-aldosterone system inhibitor washout, treatment will be administered for 108 weeks, with the final assessment at week 112, four weeks after withdrawal of study drug. RESULTS: The primary endpoint will be the slope of estimated glomerular filtration rate from week 6 to week 108. A novel surrogate efficacy endpoint, the proportion of patients achieving urinary protein-to-creatinine (UP/C) ratio of ≤1.5 g/g and >40% reduction from baseline in UP/C (FSGS partial remission endpoint: FPRE), will be evaluated at a planned interim analysis at week 36. Safety and tolerability of sparsentan will also be assessed. CONCLUSION: The phase 3 DUPLEX study will characterize the long-term antiproteinuric efficacy and nephroprotective potential of dual ETA and AT1 receptor blockade with sparsentan in patients with FSGS.

Monitoring Cough Effectiveness and Use of Airway Clearance Strategies: A Canadian and UK Survey.

BACKGROUND: Regular monitoring combined with early and appropriate use of airway clearance can reduce unplanned hospital admissions for patients with neuromuscular disease (NMD) and spinal cord injury (SCI). We aimed to describe and compare knowledge of guidelines, monitoring of cough effectiveness, clinician prescription/provision of airway clearance strategies, and service provision constraints in the United Kingdom and Canada. METHODS: This was a cross-sectional survey of clinicians affiliated with NMD and SCI clinics in Canada, 2016 attendees at the Home Mechanical Ventilation Conference in the United Kingdom, and United Kingdom physiotherapist networks. RESULTS: We received 155 surveys (92 from Canada; 63 from the United Kingdom). More UK respondents (76%) were aware of airway clearance guidelines than Canadian (56%) respondents (P = .02). Routine assessment of cough effectiveness was reported by more UK respondents (59%) than Canadian (42%) respondents (P = .044). Cough peak flow (CPF) was the most common method used in both countries, although it was more commonly used in the UK (96%) than in Canada (81%, P = .02). Fewer Canadian respondents reported using CPF before initiation of airway clearance (81% vs 94%, P = .046), and fewer Canadian respondents showed results to patients for technique feedback (76% vs 97%, P = .007). Similar participant numbers reported using CPF after initiation to ensure adequate technique (73% vs 72%, P = .92). Mechanical insufflation-exsufflation (MI-E) + lung volume recruitment (LVR) + manually assisted cough when CPF ≤ 270 L/min was most routinely recommended (41% overall). Monotherapy was infrequent (LVR 15%, manually assisted cough 7%, and MI-E 4%). More Canadians identified constraints on service provision, specifically insufficient public funding for equipment (68% vs 39%, P = .002) and inadequate community workers' knowledge (56% vs 34%, P = .002). Funding for community support was a common constraint in both countries (49% vs 42%). CONCLUSIONS: The somewhat variable cough effectiveness monitoring and airway clearance practices identified in this survey confirm the need for further work on knowledge translation related to guideline recommendations and the need to address common constraints to optimal service delivery.

Predictors of successful completion of diagnostic home sleep testing in patients with chronic kidney disease.

PURPOSE: Obstructive sleep apnea (OSA) is common among patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Home sleep testing is used to diagnose OSA in many studies investigating sleep-disordered breathing in this population. However, failure to successfully complete the test is a significant source of participant exclusion from research studies and delayed diagnosis in clinical practice. The objective of the study was to identify potential factors impeding acceptance and successful completion of home sleep testing in patients with kidney disease. METHODS: Four hundred and nineteen patients were recruited from nephrology clinics and dialysis units. Following completion of a sleep and medical history questionnaire, all patients were invited to perform a single night, home sleep study. Acceptance or refusal of the test was noted, as well as the success of the sleep study, as determined by a review of the raw data by a sleep medicine physician. RESULTS: Male gender (OR = 1.61, CI = 1.02-2.53), hypertension (OR = 2.01, CI = 1.17-3.45), and snoring (OR = 1.75, CI = 1.11-2.77) were associated with sleep test acceptance. Older patients were less likely to accept the test (OR = 0.48, CI = 0.30-0.76). Diabetics were less likely to complete the sleep test successfully (OR = 0.28, CI = 0.12-0.66). CONCLUSIONS: Advanced age is an important factor in test refusal and complications of diabetes contributes to test failure. Symptom matching may be a source of selection bias, as patients with risk factors for OSA are more likely to accept the diagnostic test.

Short-term potentiation in the control of pharyngeal muscles in obstructive apnea patients.

STUDY OBJECTIVES: To determine if activation of the genioglossus (GG) muscle during obstructive apnea events involves short-term potentiation (STP) and is followed by sustained activation beyond the obstructive phase (after-discharge). DESIGN: Physiological study. SETTING: Sleep laboratory in a tertiary hospital. PARTICIPANTS: Twenty-one patients with obstructive apnea. INTERVENTIONS: Polysomnography on continuous positive airway pressure (CPAP) with measurement of genioglossus activity. Brief dial-downs of CPAP to induce obstructive events. MEASUREMENTS AND RESULTS: Peak, phasic, and tonic genioglossus activities were measured breath-by-breath before, during, and following three-breath obstructions. Tonic but not phasic activity increased immediately following the first obstructed breath (4.9 ± 1.6 versus 3.6 ± 1.2 %GGMAX; P = 0.01) under conditions where stimuli to genioglossus activation were likely constant, strongly implicating STP in mediating recruitment of tonic activity. Both phasic and tonic activities declined slowly after relief of obstruction (after-discharge). Decay time constants were systematically shorter for phasic than for tonic activity (7.5 ± 3.8 versus 18.1 ± 8.4 sec; P < 0.001). Decay time-constant of peak activity correlated with tonic, but not phasic, recruitment. Cortical arousal near the end of obstruction resulted in a lower after-discharge (P < 0.01). Contribution of tonic activity to the increase in peak activity (6-65%Peak), as well as the decay constant (6-30 sec), varied considerably among patients. CONCLUSIONS: Short-term potentiation contributes to recruitment of the genioglossus during obstructive episodes and results in sustained tonic activity beyond the obstructive phase, thereby potentially preventing recurrence of obstruction. Wide response differences among subjects suggest that this mechanism may contribute to severity of the disorder. The after-discharge is inhibited following cortical arousal, potentially explaining arousals' destabilizing effect.

Limitations of split-night polysomnography for the diagnosis of nocturnal hypoventilation and titration of non-invasive positive pressure ventilation in amyotrophic lateral sclerosis.

Split-night polysomnography is performed at our centre in all patients with ALS who require assessment for nocturnal hypoventilation and their response to non-invasive ventilation. The purpose of this study was to determine how successful this practice has been, reflected by whether a complete assessment was achieved by a single split-night polysomnogram. We undertook a systematic, retrospective review of all consecutive split-night polysomnograms in ALS patients between 2005 and 2012. A total of 47 cases were reviewed. Forty-three percent of patients had an incomplete test, resulting in a recommendation to repeat the polysomnogram. Poor sleep efficiency and absence of REM sleep in the diagnostic portion of the study were strongly associated with incomplete studies. Clinical variables that reflect severity of ALS (FVC, PaCO2, ALSFRS-R) and use of REM-suppressing antidepressants or sedative-hypnotics were not associated with incomplete split-night polysomnogram. In conclusion, a single, split-night polysomnogram is frequently inconclusive for the assessment of nocturnal hypoventilation and complete titration of non-invasive positive pressure ventilation in patients with ALS. Poor sleep efficiency and absence of REM sleep are the main limitations of split-night polysomnography in this patient population.

The prevalence of restless legs syndrome across the full spectrum of kidney disease.

STUDY OBJECTIVES: Although restless legs syndrome (RLS) is common and well recognized as an important and potentially treatable cause of sleep disruption in end-stage renal disease (ESRD), few studies have evaluated the prevalence of RLS and its impact on sleep in the non-dialysis-dependent chronic kidney disease (CKD) population. The objectives of the study were to determine the prevalence of RLS across the full spectrum of kidney disease and to assess the impact of RLS on sleep quality and daytime function. METHODS: Five hundred patients were recruited from nephrology clinics and were stratified according to estimated glomerular filtration rate (EGFR): eGFR ≥ 60 mL/min/1.73m(2) (n = 127), CKD (eGFR < 60, not on dialysis, n = 242), and ESRD (on hemodialysis, n = 131). All subjects completed a sleep and medical history questionnaire, an RLS questionnaire, the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS). RESULTS: The prevalence of RLS did not differ among the three groups (18.9% [eGFR ≥ 60], 26% (CKD), and 26% (ESRD) p = 0.27). However, many symptoms of sleep disruption were more common in patients with RLS, and RLS was independently correlated with the PSQI score both in the full cohort (OR = 2.63, CI = 1.60-4.00, p < 0.001) and the CKD group (OR = 2.39, CI = 1.20-4.79, p = 0.014). CONCLUSIONS: RLS is common in non-dialysis-dependent CKD patients and is an important source of sleep disruption.

Diagnostic value of screening instruments for identifying obstructive sleep apnea in kidney failure.

BACKGROUND: Patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD) have a high prevalence of obstructive sleep apnea (OSA) that can have significant clinical implications. An accurate clinical screening tool for OSA that identifies patients for further diagnostic testing would assist in the identification of this comorbidity. The Berlin Questionnaire (BQ), Adjusted Neck Circumference (ANC), and STOP-BANG questionnaire are 3 such instruments that have been validated in patients with normal kidney function. OBJECTIVE: The objective of this study was to determine the validity of these screening instruments in patients with CKD and ESRD, using overnight cardiopulmonary monitoring to diagnose OSA. METHODS: One hundred seventy-two patients were recruited from nephrology clinics and hemodialysis units (CKD: n = 109; ESRD: n = 63). All patients completed the BQ, ANC, STOP-BANG, and overnight cardiopulmonary monitoring to diagnose OSA (respiratory disturbance index [RDI] ≥ 15). Sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for the BQ, ANC, and STOP-BANG. RESULTS: Obstructive sleep apnea was present in 41 CKD patients (38%) and 32 ESRD patients (51%). All screening instruments had satisfactory sensitivity (56% to 94%) but poor specificity (29% to 77%) and low accuracy (51% to 69%) in both CKD and ESRD patients with RDI ≥ 15. Using an RDI ≥ 30 yielded similar results. CONCLUSIONS: Current screening questionnaires do not accurately identify patients at high risk for OSA or rule out the presence of OSA in patients with CKD and ESRD. Consequently, objective monitoring during sleep is required to reliably identify sleep apnea in these patient populations.

Clinical presentation of obstructive sleep apnea in patients with chronic kidney disease.

BACKGROUND: Obstructive sleep apnea (OSA) is an important and common comorbidity in patients with chronic kidney disease (CKD). However, few studies have addressed how OSA presents in this patient population and whether it is clinically apparent. OBJECTIVE: The objectives of this study were to determine if the prevalence and severity of sleep related symptoms distinguished CKD patients with OSA from those without apnea, and whether the clinical presentation of OSA in CKD patients differed from the general OSA population. METHODS: One hundred nineteen patients were recruited from outpatient nephrology clinics. All patients completed a sleep history questionnaire, the Epworth Sleepiness Scale (daytime sleepiness, ESS > 10), the Pittsburgh Sleep Quality Index (poor sleep quality, PSQI > 5), and underwent overnight cardiopulmonary monitoring for determination of sleep apnea (respiratory disturbance index ≥ 15). CKD patients with OSA (n = 46) were compared to (1) CKD patients without OSA (n = 73) and (2) OSA patients without CKD (n = 230) who were referred to the sleep centre. RESULTS: The prevalence of OSA symptoms and PSQI scores did not differ between CKD patients with OSA and CKD patients without apnea. Although the prevalence of daytime sleepiness was higher in CKD patients with OSA compared to CKD patients without apnea (39% vs. 19%, p = 0.033), both daytime sleepiness and other symptoms of sleep apnea were considerably less frequent than in OSA patients without a history of kidney disease. CONCLUSIONS: The presence of OSA in patients with CKD is unlikely to be clinically apparent. Consequently, objective cardiopulmonary monitoring during sleep is required to reliably identify this comorbidity.

Declining kidney function increases the prevalence of sleep apnea and nocturnal hypoxia.

BACKGROUND: Sleep apnea is an important comorbidity in patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Although the increased prevalence of sleep apnea in patients with ESRD is well established, few studies have investigated the prevalence of sleep apnea in patients with nondialysis-dependent kidney disease, and no single study, to our knowledge, has examined the full spectrum of kidney function. We sought to determine the prevalence of sleep apnea and associated nocturnal hypoxia in patients with CKD and ESRD. We hypothesized that the prevalence of sleep apnea would increase progressively as kidney function declines. METHODS: Two hundred fifty-four patients were recruited from outpatient nephrology clinics and hemodialysis units. All patients completed an overnight cardiopulmonary monitoring test to determine the prevalence of sleep apnea (respiratory disturbance index ≥ 15) and nocturnal hypoxia (oxygen saturation < 90% for ≥ 12% of monitoring). Patients were stratified into three groups based on estimated glomerular filtration rate (eGFR) as follows: eGFR ≥ 60 mL/min/1.73 m(2) (n = 55), CKD (eGFR < 60 mL/min/1.73 m(2) not on dialysis, n = 124), and ESRD (on hemodialysis, n = 75). RESULTS: The prevalence of sleep apnea increased as eGFR declined (eGFR ≥ 60 mL/min/1.73 m(2), 27%; CKD, 41%; ESRD, 57%; P = .002). The prevalence of nocturnal hypoxia was higher in patients with CKD and ESRD (eGFR ≥ 60 mL/min/1.73 m(2), 16%; CKD, 47%; ESRD, 48%; P < .001). CONCLUSIONS: Sleep apnea is common in patients with CKD and increases as kidney function declines. Almost 50% of patients with CKD and ESRD experience nocturnal hypoxia, which may contribute to loss of kidney function and increased cardiovascular risk.

Genioglossus activity available via non-arousal mechanisms vs. that required for opening the airway in obstructive apnea patients.

It is generally believed that reflex recruitment of pharyngeal dilator muscles is insufficient to open the airway of obstructive apnea (OSA) patients once it is closed and, therefore, that arousal is required. Yet arousal promotes recurrence of obstruction. There is no information about how much dilator [genioglossus (GG)] activation is required to open the airway (GG Opening Threshold) or about the capacity of reflex mechanisms to increase dilator activity before/without arousal (Non-Arousal Activation). The relationship between these two variables is important for ventilatory stability. We measured both variables in 32 OSA patients (apnea-hypopnea index 74 ± 42 events/h). GG activity was monitored while patients were on optimal continuous positive airway pressure (CPAP). Zopiclone was administered to delay arousal. Maximum GG activity (GG(MAX)) and airway closing pressure (P(CRIT)) were measured. During stable sleep CPAP was decreased to 1 cmH(2)O to induce obstructive events and the dial-downs were maintained until the airway opened with or without arousal. GG activity at the instant of opening (GG Opening Threshold) was measured. GG Opening Threshold averaged only 10.4 ± 9.5% GG(Max) and did not correlate with P(CRIT) (r = 0.04). Twenty-six patients had >3 openings without arousal, indicating that Non-Arousal Activation can exceed GG Opening Threshold in the majority of patients. GG activity reached before arousal in Arousal-Associated Openings was only 5.4 ± 4.6% GG(MAX) below GG Opening Threshold. We conclude that in most patients GG activity required to open the airway is modest and can be reached by non-arousal mechanisms. Arousals occur in most cases just before non-arousal mechanisms manage to increase activity above GG Opening Threshold. Measures to reduce GG Opening Threshold even slightly may help stabilize breathing in many patients.

Response of genioglossus muscle to increasing chemical drive in sleeping obstructive apnea patients.

STUDY OBJECTIVES: Subjects with a collapsible upper airway must activate their pharyngeal dilators sufficiently in response to increasing chemical drive if they are to maintain airway patency without arousal from sleep. Little is known about the response of pharyngeal dilators to increasing chemical drive in these subjects. We wished to determine, in obstructive apnea patients, the response of the genioglossus to increasing chemical drive and the contribution of mechanoreceptor feedback to this response. DESIGN: Physiological study. SETTING: University-based sleep laboratory. PATIENTS: 20 patients with obstructive apnea. INTERVENTIONS: Genioglossus activity was monitored during overnight polysomnography on optimal continuous positive airway pressure (CPAP). Intermittently, inspired gases were altered to produce different levels of ventilatory stimulation. CPAP was then briefly reduced to 1.0 cm H(2)O (dial-down), inducing an obstruction. MEASUREMENTS AND RESULTS: Without mechanoreceptor feedback (i.e., on CPAP) the increase in genioglossus activity as ventilation increased from 6.1 ± 1.4 to 16.1 ± 4.8 L/min was modest (ΔTonic activity 0.3% ± 0.5%maximum; ΔPhasic activity 1.7% ± 3.4%maximum). Genioglossus activity increased immediately upon dial-down, reflecting mechanoreceptor feedback, but only when ventilation before dial-down exceeded a threshold value. This threshold varied among patients and, once surpassed, genioglossus activity increased briskly with further increases in chemical drive (1.1% ± 0.84%GG(MAX) per L/min increase in V(E)). CONCLUSIONS: In sleeping obstructive apnea patients: (1) Mechanoreceptor feedback is responsible for most of the genioglossus response to chemical drive. (2) Mechanoreceptor feedback is effective only above a threshold chemical drive, which varies greatly among patients. These findings account in part for the highly variable relation between pharyngeal mechanical abnormalities and apnea severity.

Sleep disruption in patients with sleep apnea and end-stage renal disease.

OBJECTIVES: Sleep apnea (SA) is common in patients with end-stage renal disease (ESRD) and such patients are likely to suffer additional sleep disruption associated with restless legs syndrome (RLS) and periodic leg movements (PLM). Our objective was to evaluate sleep quality in ESRD patients who are newly diagnosed with SAand determine the additional contribution of PLM to sleep disruption. METHODS: Two groups of patients with SA (apnea-hypopnea index (AHI) > 15) were compared, one with ESRD (n = 12) and the other with normal renal function (n = 18), using a sleep history questionnaire, sleep diary, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, polysomnography (1 night) and actigraphy (6 nights). RESULTS: The prevalence of RLS was higher in ESRD patients (60% vs 6%, p < 0.001). ESRD patients had shorter total sleep time (TST) (264 +/- 78 vs 330 +/- 46 min, p = 0.01), lower sleep efficiency (68 +/- 20 % vs 81 +/- 11 %, p = 0.03), and more stage 1 NREM sleep (23 +/- 18 vs 8 +/- 5 % TST, p = 0.002). ESRD patients had a higher frequency of PLM (31 +/- 37 hr-1 vs 8.0 +/- 16 hr-1, p = 0.02) and PLM-related arousals (15 +/- 18 hr-1 vs 1 +/- 2 hr-1, p = 0.003). Actigraphy demonstrated a higher movement and fragmentation index in ESRD patients (23 +/- 10 % sleep time vs 17 +/- 6 % sleep time, p = 0.04). CONCLUSIONS: The co-existence of PLM is an additional source of sleep disruption in patients with ESRD and SA. Treatment of PLM, in addition to treatment of sleep apnea, may be required to improve sleep quality in this patient population.

Determinants of ventilatory instability in obstructive sleep apnea: inherent or acquired?

STUDY OBJECTIVES: Certain respiratory control characteristics determine whether patients with collapsible upper airway develop stable or unstable breathing during sleep, thereby influencing the severity of obstructive apnea (OSA). These include arousal threshold (T(A)), response to transient hypoxia and hypercapnia (Dynamic Response) and the increase in respiratory drive required for arousal-free airway opening (T(ER)). We wished to determine whether these characteristics are inherent or are acquired during untreated OSA. DESIGN: T(A), Dynamic Response, and T(ER) were measured in patients with severe OSA before and after treatment with continuous positive airway pressure (CPAP). Changes observed after treatment were deemed to have been acquired during untreated OSA. SETTING: University-based sleep laboratory. PATIENTS: 15 patients with severe OSA. INTERVENTIONS: (1) 30-sec alterations in inspired gases during sleep on CPAP. (2) Brief dial-downs of CPAP (dial-downs) both during air breathing and when ventilation was increased to different levels. MEASUREMENTS AND RESULTS: T(A): the increase in ventilation associated with a 50% probability of arousal (T(A)50). Dynamic Response: the increase in ventilation on the 5th breath following breathing 3% CO2 in 11% to 15% O2. T(ER): the increase in ventilation prior to dial-downs that was associated with an arousal-free airway opening during dial-down. CPAP therapy (10.5 +/- 4.3 months) resulted in marked reduction in Dynamic Response (131% +/- 95% to 52% +/- 34% baseline ventilation, P < 0.005), a decrease in T(A)50 (134% +/- 78% to 86% +/- 47% baseline ventilation, P < 0.05), and no change in T(ER). CONCLUSIONS: T(ER) may be an inherent characteristic. Untreated OSA results in an increase in dynamic response to asphyxia and an increase in arousal threshold.

Improving rates of pneumococcal vaccination on discharge from a tertiary center medical teaching unit: a prospective intervention.

BACKGROUND: Pneumococcal disease causes significant morbidity and mortality in at-risk individuals, and is complicated by emerging antibiotic resistance. An effective, safe and cost-effective vaccine is available, but despite this many patients who would benefit from pneumococcal vaccination remain unvaccinated. The purpose of this study was to determine the rates of missed opportunities to provide pneumococcal vaccination to patients being discharged from a tertiary center medical teaching unit and to determine if a nurse coordinator-based intervention would increase rates of pneumococcal vaccination prior to discharge home. METHODS: We conducted a prospective, controlled study in the setting of a Medical Teaching Unit at a tertiary care centre to assess the impact of a nurse coordinator based intervention on the rates of vaccination of eligible patients on discharge home. The rates of vaccination during an eight-week usual-care period (February 20 to April 16, 2002) and an eight-week intervention period (April 22 to June 16, 2002) were compared. RESULTS: Prior to the intervention none of thirty-eight eligible patients were vaccinated prior to discharge home from the Medical Teaching Unit. After the intervention 27 (54%) of fifty eligible patients were vaccinated prior to discharge. CONCLUSION: There are significant missed opportunities to provide pneumococcal vaccination to inpatients who are discharged home from a medical unit. Using a patient care coordinator we were able to significantly improve the rates of vaccination on discharge.

Validity of ICD-9-CM administrative data for determining eligibility for pneumococcal vaccination triggers.

The purpose of this study was to evaluate the efficacy of medical record administrative data as coded by the International Classification of Diseases, Ninth Revision, for triggering pneumococcal vaccination reminders of patients following discharge from a tertiary care adult teaching hospital. A retrospective computerized search was conducted using administrative discharge data to detect patients admitted to the medical teaching unit who met clinical criteria for pneumococcal vaccination according to Canadian immunization guidelines. For identification of persons eligible for vaccination, administrative discharge data showed a sensitivity of 83% (confidence interval [CI], 0.73-0.92) and a specificity of 78% (CI, 0.64-0.91), with a positive predictive value of 87% (CI, 0.83-0.90) and a negative predictive value of 72% (CI, 0.58-0.86). The reasonably high specificity and sensitivity of diagnostic codes in administrative data could be used to trigger appropriate pneumococcal vaccination among eligible patients after hospital discharge.

Thunderclap headache and reversible segmental cerebral vasoconstriction associated with use of oxymetazoline nasal spray.

Oxymetazoline is a sympathomimetic amine found in over-the-counter nasal decongestants. We report a case of chronic use of nasal oxymetazoline associated with thunderclap headache due to reversible segmental intracranial vasoconstriction.

Stage of chronic kidney disease predicts seroconversion after hepatitis B immunization: earlier is better.

BACKGROUND: Hepatitis B virus (HBV) infection remains a concern in dialysis populations, and vaccination programs have been less successful than those in the general population. Reasons for poor response include malnutrition, uremia, and the generalized immunosuppressive state of patients with chronic kidney disease (CKD). This prospective cohort study evaluated factors impacting on the effectiveness of a vaccination program before dialysis therapy initiation, including level of kidney function. METHODS: All patients receiving care in the Kidney Function Clinic (St Paul's Hospital, Vancouver, Canada) were screened for previous HBV infection or vaccination. Those who were marker negative were administered a standardized hepatitis B vaccination schedule recommended for patients with CKD. The primary outcome measure, seroconversion, is defined as hepatitis B surface antibody titer greater than 10 IU 3 months after completion of the vaccination schedule. RESULTS: The study population of 165 patients included 64% men with a mean age of 60 years, mean serum creatinine level of 3.4 +/- 1.5 mg/dL (300 +/- 133 micromol/L), and median estimated glomerular filtration rate (GFR) of 20 mL/min (interquartile range, 14 to 20). Seroconversion rate was 82%. Multivariate analyses showed the independent predictive value of level of GFR. The model showed that patients with the lowest level of kidney function and who were older and had diabetes were less likely to seroconvert (P < 0.05). CONCLUSION: This is the largest study to show in a well-characterized cohort that patients with higher GFR levels are more likely to respond to hepatitis B vaccination programs with seroconversion, independent of other factors. Future studies will explore specific mechanisms to explain this phenomenon.