Gaurav Nigam

Nasal Expiratory Positive Airway Pressure Devices (Provent) for OSA: A Systematic Review and Meta-Analysis

Objective. To quantify the effectiveness of nasal expiratory positive airway pressure (nasal EPAP) devices or Provent as treatment for obstructive sleep apnea (OSA). Methods. PubMed and six other databases were searched through November 15, 2015, without language limitations. Results. Eighteen studies (920 patients) were included. Pre- and post-nasal EPAP means ± standard deviations (M ± SD) for apnea-hypopnea index (AHI) in 345 patients decreased from 27.32 ± 22.24 to 12.78 ± 16.89 events/hr (relative reduction = 53.2%). Random effects modeling mean difference (MD) was −14.78 events/hr [95% CI −19.12, −10.45], p value < 0.00001. Oxygen desaturation index (ODI) in 247 patients decreased from 21.2 ± 19.3 to 12.4 ± 14.1 events/hr (relative reduction = 41.5%, p value < 0.00001). Lowest oxygen saturation (LSAT) M ± SD improved in 146 patients from 83.2 ± 6.8% to 86.2 ± 11.1%, MD 3 oxygen saturation points [95% CI 0.57, 5.63]. Epworth Sleepiness Scale (ESS) M ± SD improved (359 patients) from 9.9 ± 5.3 to 7.4 ± 5.0, MD −2.5 [95% CI −3.2, −1.8], p value < 0.0001. Conclusion. Nasal EPAP (Provent) reduced AHI by 53.2%, ODI by 41.5% and improved LSAT by 3 oxygen saturation points. Generally, there were no clear characteristics (demographic factors, medical history, and/or physical exam finding) that predicted favorable response to these devices. However, limited evidence suggests that high nasal resistance could be associated with treatment failure. Additional studies are needed to identify demographic and polysomnographic characteristics that would predict therapeutic success with nasal EPAP (Provent).

A systematic review on prevalence and risk factors associated with treatment- emergent central sleep apnea

Introduction: Treatment-emergent central sleep apnea (TECSA) is the appearance of central apneas and hypopneas after significant resolution of the obstructive events has been attained using positive airway pressure (PAP) therapy. The aim of the study was to determine the prevalence of TECSA and to understand what factors are associated with its development. Methods: PubMed, MEDLINE, Scopus, Web of Science and Cochran Library databases were searched with Mesh headings to locate studies linking TECSA and obstructive sleep apnea (OSA). Results: Nine studies were identified that reported the prevalence of TECSA ranging from 5.0% to 20.3%. Prevalence of TECSA for studies using only full night titration was between 5.0% and 12.1% where as it was between 6.5% and 20.3% for studies using split-night polysomnogram. The mean effective continuous PAP (CPAP) setting varied between 7.5 cm and 15.2 cm of water for patients in TECSA group and between 7.4 cm and 13.6 cm of water for the group without TECSA. Conclusions: The aggregate point prevalence of TECSA is about 8% with the estimated range varying from 5% to 20% in patients with untreated OSA. The prevalence tends to be higher for split-night studies compared to full night titration studies. TECSA can occur at any CPAP setting although extremely high CPAP settings could increase the likelihood. Male gender, higher baseline apnea-hypopnea index, and central apnea index at the time of diagnostic study could be associated with the development of TECSA at a subsequent titration study.

Sleep Related Scratching: A Distinct Parasomnia?

ABSTRACT Pruritus (itching) during the sleep period can present as a symptom of dermatological or systemic disease, or as a parasomnia. Sleep related scratching as a primary parasomnia, exclusively confined to sleep in the absence of coexisting dermatological disorders, has not been well described. This case series describes three such patients, and discusses potentially relevant pathophysiology that can underlie itching or pain. Such cases of sleep related scratching may merit nosologic classification apart from previously defined parasomnias.

Exploring sleep disorders in patients with chronic kidney disease

Kidney disorders have been associated with a variety of sleep-related disorders. Therefore, researchers are placing greater emphasis on finding the role of chronic kidney disease (CKD) in the development of obstructive sleep apnea and restless legs syndrome. Unfortunately, the presence of other sleep-related disorders with CKDs and non-CKDs has not been investigated with the same clinical rigor. Recent studies have revealed that myriad of sleep disorders are associated with CKDs. Furthermore, there are a few non-CKD-related disorders that are associated with sleep disorders. In this narrative review, we provide a balanced view of the spectrum of sleep disorders (as identified in International Classification of Sleep disorders-3) related to different types of renal disorders prominently including but not exclusively limited to CKD.

Nasal Dilators (Breathe Right Strips and NoZovent) for Snoring and OSA: A Systematic Review and Meta-Analysis

Objective. To systematically review the international literature for studies evaluating internal (NoZovent) and external (Breathe Right Strips) nasal dilators as treatment for obstructive sleep apnea (OSA). Study Design. Systematic review with meta-analysis. Methods. Four databases, including PubMed/MEDLINE, were searched through September 29, 2016. Results. One-hundred twelve studies were screened, fifty-eight studies were reviewed, and fourteen studies met criteria. In 147 patients, the apnea-hypopnea index (AHI) was reported, and there was an improvement from a mean ± standard deviation (M ± SD) of 28.7 ± 24.0 to 27.4 ± 23.3 events/hr, p value 0.64. There was no significant change in AHI, lowest oxygen saturation, or snoring index in OSA patients when using nasal dilators. However, a subanalysis demonstrated a slight reduction in apnea index (AI) with internal nasal dilators (decrease by 4.87 events/hr) versus minimal change for external nasal dilators (increase by 0.64 events/hr). Conclusion. Although nasal dilators have demonstrated improved nasal breathing, they have not shown improvement in obstructive sleep apnea outcomes, with the exception of mild improvement in apnea index when internal nasal dilators were used.

Rapid Eye Movement (REM) rebound on initial exposure to CPAP therapy: a systematic review and meta-analysis

ObjectiveRapid Eye Movement (REM) rebound is a polysomnographic phenomenon where a substantial increase in REM sleep is noted in patients with untreated obstructive sleep apnea (OSA) when first undergoing continuous positive airway pressure (CPAP) titration. The objectives of this study are to determine: 1) the percentage of patients experiencing REM rebound during CPAP titrations, 2) to quantify the relative increase in REM sleep duration and 3) to identify if there are patient variables associated with REM rebound.MethodsFour databases (including PubMed/Medline) were systematically searched through March 12, 2017.ResultsFour hundred sixty-seven articles were screened, 58 were reviewed in full-text form and 14 studies met the criteria for inclusion in this review. Eleven of the fourteen studies noted a statistically significant increase in amount of REM sleep during the titration night, compared to baseline sleep study. Pre- and post-CPAP REM sleep duration percentage means ± standard deviations (M ± SD) in 1119 patients increased from 13.8 ± 8.2% to 20.0 ± 10.1%; random effects modeling demonstrated a mean difference of 7.86 (%) [95% CI 5.01, 10.70], p-value <0.00001, corresponding to a 57% relative increase in REM sleep duration. The standardized mean difference (SMD) is 0.90 [95% CI 0.59, 1.22], representing a large magnitude of effect.ConclusionsIn studies reporting REM rebound, the REM sleep duration increased by 57% during the first CPAP titration night compared to the baseline sleep study. The prevalence of REM rebound varied between 23 and 46%. A low amount of REM sleep on the diagnostic PSG predicted REM rebound.

Use of Auto-titrating Positive Airway Pressure Devices for Sleep-disordered Breathing: The Good, the Bad and the Ugly

Auto-titrating positive airway pressure (APAP) devices are an effective treatment alternative for certain patients with obstructive sleep apnea (OSA). In patients with positional sleep apnea and sleep stage dependent OSA, APAP devices may be more preferable than continuous positive airway pressure (CPAP). The myriad of APAP machines currently available employ increasingly sophisticated mathematical algorithms to identify and ameliorate respiratory disturbances. The cardiovascular benefits accrued from consistent CPAP usage still remain to be proven with APAP use. Although a reasonable alternative to CPAP, APAP titration or treatment should not be used in patients in whom OSA coexists with risk factors for central sleep apnea and hypoventilation syndromes.

Natural history of treatment-emergent central sleep apnea on positive airway pressure: A systematic review

INTRODUCTION: Treatment-emergent central sleep apnea (TECSA) is observed in some patients when they are treated with positive airway pressure (PAP) after significant resolution of the preexisting obstructive events in patients with obstructive sleep apnea. The objective of this study was to systematically review the literature for studies describing the natural history of TECSA. METHODS: PubMed, Medline, Scopus, Web of Science, and Cochran Library databases were searched through June 29, 2017. RESULTS: Five studies were identified that discussed the natural history of TECSA. TECSA developed in 3.5%–19.8% of PAP-treated patients. Treatment-persistent central sleep apnea (TPCSA), representing protracted periods of PAP therapy-related central apneas, was noted in 14.3%–46.2% of patients with TECSA. Delayed-TECSA (D-TECSA) represents an anomalous TECSA entity appearing weeks to months after initial PAP therapy. D-TECSA was observed in 0.7%–4.2% of OSA patients undergoing PAP treatment (after at least 1 month). In patients with TECSA, a higher apnea–hypopnea index (AHI) and central apnea index at their baseline study or a higher residual AHI at their titration study may be associated with an increased likelihood of conversion to TPCSA. CONCLUSIONS: Overall, TECSA developed in 3.5%–19.8% of PAP-treated patients with OSA. The vast majority will experience complete resolution of central apneas over a few weeks to months. Unfortunately, about a third of patients with TECSA may continue to exhibit persistence of central sleep apnea on reevaluation. A small proportion may experience D-TECSA after few weeks to several months of initial exposure to PAP therapy.

Drug rash with eosinophilia and systemic symptoms (DRESS) caused by phenytoin

Drug rash with eosinophilia and systemic symptoms (DRESS) is a rare but potentially life-threatening condition with high mortality. Diagnosis is challenging due to variable clinical presentation and a protracted latency period following initiation of the offending drug. DRESS is a complex interplay that starts by introduction of the offending drug, reactivation of viruses and activation of the immune system. Herpes virus reactivation is considered a diagnostic marker and indicator of illness severity. Prompt recognition and the removal of offending agent remain the key to successful treatment. In cases of severe organ involvement, corticosteroids, immunoglobulins, antiviral and specialist consultation may be helpful. Here we present a case of a 36-year-old African-American male who presented with symptoms mimicking sepsis with an associated skin eruption that was diagnosed as DRESS.

Probing the prevalence of central sleep apnea in patients with chronic kidney disease.

Dear editor, It is with great interest that we read the editorial written by Silva et al. Here, they briefly discussed the crucial possibility of underestimation in the prevalence of central sleep apnea (CSA) in patients with chronic kidney disease (CKD) as determined by a recent systematic review conducted by Nigam et al. [1] In that systematic review, Nigam et al. reported an aggregate point prevalence of CSA in adults with CKD to be about 10 % while acknowledging that the overall prevalence of CSA in CKD varies widely between 0 and 75 %. This systematic review demonstrates that our understanding of the association of CSA and CKD is still evolving. The results of our investigation while important, are still preliminary. Various pathophysiological mechanisms leading to the development of CSA have fluid overload as the common denominator. It is likely that timing of the sleep study and changes in volume status related to duration and type of dialysis affect the presence and severity of reported CSA. Hypothetically, extraction of extra fluid after dialysis should improve the severity of CSA. Whether all modalities of dialysis will lead to transient improvement in CSA severity remains to be seen, pending further clinical investigation. Unfortunately, the goal of our study was not to determine the changes in CSA severity with changes in total body water in patients with CKD. A systematic review with meta-analysis on that topic may be able to provide more clarity, although heterogeneity in constituent studies and limited available data may impede an exhaustive analysis. Is 10 % aggregate point prevalence denoting proportion of CSA in patients affected with CKD, an underestimation? Given the aforementioned wide heterogeneity of 0–75 % in prevalence of CSA in CKD, this is certainly a possibility. The CSA index should ideally include both central apneas and central hypopneas [2]. Our systematic review found that only three of the eight constituent studies undertook the arduous task of recording and reporting central hypopnea index when calculating the overall CSA index. The aggregate point prevalence of CSA in CKD when including only the studies that report both central apnea and central hypopnea indices turns out to be 33.3 %, which is significantly higher than the overall aggregate point prevalence of 9.6 %, calculated by including all eight studies [3]. Limited sample size and inconsistencies around criteria used to define hypopneas in constituent studies remain the limitations of any such estimation. We agree that timing of the sleep study in relation to last run of dialysis could also impact the estimation rates for CSA prevalence. We believe our calculation of 10 % aggregate point prevalence provides the best conservative estimate that can be deduced based on the data available till date. To conclude, our work revealed that there is a definite association of CSA with CKD, but the strength of this association is not completely understood. This is due to a myriad of limitations and lack of congruity in reported results from the constituent studies. At the very least, future studies should unanimously utilize the * Gaurav Nigam dr.nigamgaurav@gmail.com