Quantifying ventilation by X-ray velocimetry in healthy adults.

RATIONALE: X-ray velocimetry (XV) has been utilized in preclinical models to assess lung motion and regional ventilation, though no studies have compared XV-derived physiologic parameters to measures derived through conventional means. OBJECTIVES: To assess agreement between XV-analysis of fluoroscopic lung images and pitot tube flowmeter measures of ventilation. METHODS: XV- and pitot tube-derived ventilatory parameters were compared during tidal breathing and with bilevel-assisted breathing. Levels of agreement were assessed using the Bland-Altman analysis. Mixed models were used to characterize the association between XV- and pitot tube-derived values and optimize XV-derived values for higher ventilatory volumes. MEASUREMENTS AND MAIN RESULTS: Twenty-four healthy volunteers were assessed during tidal breathing and 11 were reassessed with increased minute ventilation with bilevel-assisted breathing. No clinically significant differences were observed between the two methods for respiratory rate (average Δ: 0.58; 95% limits of agreement: -1.55, 2.71) or duty cycle (average Δ: 0.02; 95% limits of agreement: 0.01, 0.03). Tidal volumes and flow rates measured using XV were lower than those measured using the pitot tube flowmeter, particularly at the higher volume ranges with bilevel-assisted breathing. Under these conditions, a mixed-model based adjustment was applied to the XV-derived values of tidal volume and flow rate to obtain closer agreement with the pitot tube-derived values. CONCLUSION: Radiographically obtained measures of ventilation with XV demonstrate a high degree of correlation with parameters of ventilation. If the accuracy of XV were also confirmed for assessing the regional distribution of ventilation, it would provide information that goes beyond the scope of conventional pulmonary function tests or static radiographic assessments.

Electrocardiographic markers for the prediction of ventricular arrhythmias in patients with systemic sclerosis.

SSc is an autoimmune disease characterized by microvascular damage, endothelial dysfunction and fibrosis of the skin and the internal organs. Cardiac manifestation in patients with SSc is one of the major organ involvements. Approximately 20% of SSc patients suffer from primary cardiovascular disease and another 20% may have secondary cardiac involvement. Although cardiac arrhythmias are mostly linked to myocardial fibrosis, atrioventricular conduction abnormalities are secondary to the fibrosis of the pulse conduction system. Despite the severe consequences of ventricular rhythm disturbances in patients with SSc, the exact role of electrocardiographic markers in the prediction of these arrhythmias has not yet been clearly elucidated. Therefore, the question is whether certain ECG parameters reflecting ventricular repolarization may help to recognize scleroderma patients with increased risk for ventricular arrhythmias and sudden cardiac death.

Cardiovascular risk factors differently affect the survival of patients undergoing manual or mechanical resuscitation.

BACKGROUND: Chest compression is a decisive element of cardio-pulmonary resuscitation (CPR). By applying a mechanical CPR device, compression interruptions can be minimised. We examined the efficiency of manual and device-assisted resuscitation as well as the effects of cardiovascular risk factors on the outcome of resuscitation. METHODS: In our retrospective, randomised 3-year study the data of adult patients suffering non-traumatic, out-of-hospital, sudden cardiac death (SCD) were analysed (n = 287). The data were retrieved by processing case reports, Utstein sheets and acute coronary syndrome sheets. We compared the data of patients undergoing manual (n = 232) and device-assisted resuscitation (LUCAS-2, n = 55). The primary endpoint was the on-site restoration of spontaneous circulation (ROSC). RESULTS AND CONCLUSION: In 37% of the cases ROSC happened. With respect to ROSC an insignificantly more favourable tendency was demonstrated in the case of device-assisted resuscitation (p = 0.072). In the Lucas group, a higher success rate occurred even in the case of prolonged resuscitation. We found a better outcome in the Lucas group in the case of CPR started a longer time after the SCD (p < 0.05). A positive correlation was established between age and unsuccessful resuscitation (p = < 0.017; r = 0.125). An unfavourable correlation was observed between hypertension and the outcome of resuscitation (p = 0.018; r = 0.143). According to our results the presence of left ventricular hypertrophy poses 5.1-fold risk of unsuccessful CPR (CI: 4.97-5.29). Advanced age and structural heart diseases can play a role in the genesis of SCD. Importantly, left ventricular hypertrophy and hypertension negatively affect survival.

Functional imaging for assessing regional lung ventilation in preclinical and clinical research.

Dynamic heterogeneity in lung ventilation is an important measure of pulmonary function and may be characteristic of early pulmonary disease. While standard indices like spirometry, body plethysmography, and blood gases have been utilized to assess lung function, they do not provide adequate information on regional ventilatory distribution nor function assessments of ventilation during the respiratory cycle. Emerging technologies such as xenon CT, volumetric CT, functional MRI and X-ray velocimetry can assess regional ventilation using non-invasive radiographic methods that may complement current methods of assessing lung function. As a supplement to current modalities of pulmonary function assessment, functional lung imaging has the potential to identify respiratory disease phenotypes with distinct natural histories. Moreover, these novel technologies may offer an optimal strategy to evaluate the effectiveness of novel therapies and therapies targeting localized small airways disease in preclinical and clinical research. In this review, we aim to discuss the features of functional lung imaging, as well as its potential application and limitations to adoption in research.

Changes in tongue morphology predict responses in pharyngeal patency to selective hypoglossal nerve stimulation.

STUDY OBJECTIVES: The major goal of the study was to determine whether changes in tongue morphology under selective hypoglossal nerve therapy for obstructive sleep apnea were associated with alterations in airway patency during sleep when specific portions of the hypoglossal nerve were stimulated. METHODS: This case series was conducted at the Johns Hopkins Sleep Disorders Center at Johns Hopkins Bayview Medical Center. Twelve patients with apnea implanted with a multichannel targeted hypoglossal nerve-stimulating system underwent midsagittal ultrasound tongue imaging during wakefulness. Changes in tongue shape were characterized by measuring the vertical height and polar dimensions between tongue surface and genioglossi origin in the mandible. Changes in patency were characterized by comparing airflow responses between stimulated and adjacent unstimulated breaths during non-rapid eye movement sleep. RESULTS: Two distinct morphologic responses were observed. Anterior tongue base and hyoid-bone movement (5.4 [0.4] to 4.1 [1.0] cm (median and [interquartile range]) with concomitant increases in tongue height (5.0 [0.9] to 5.6 [0.7] cm) were associated with decreases in airflow during stimulation. In contrast, comparable anterior hyoid movement (tongue protrusion from 5.8 [0.5] to 4.5 [0.9] cm) without significant increases in height (5.2 [1.6] to 4.6 [0.8] cm) were associated with marked increases in airflow during sleep. CONCLUSIONS: Tongue protrusion with preservation of tongue shape predicted increases in patency, whereas anterior movement with concomitant increases in height were associated with decreased pharyngeal patency. These findings suggest that pharyngeal patency can be best stabilized by stimulating lingual muscles that maintain tongue shape while protruding the tongue, thereby preventing it from prolapsing posteriorly during sleep. CITATION: Fleury Curado T, Pham L, Otvos T, et al. Changes in tongue morphology predict responses in pharyngeal patency to selective hypoglossal nerve stimulation. J Clin Sleep Med. 2023;19(5):947-955.

Cardiopulmonary Resuscitation With Mechanical Chest Compression Device During Percutaneous Coronary Intervention. A Case Report.

Sudden cardiac death is a leading cause of death worldwide, whereby myocardial infarction is considered the most frequent underlying condition. Percutaneous coronary intervention (PCI) is an important component of post-resuscitation care, while uninterrupted high-quality chest compressions are key determinants in cardiopulmonary resuscitation (CPR). In our paper, we evaluate a case of a female patient who suffered aborted cardiac arrest due to myocardial infarction. The ambulance crew providing prehospital care for sudden cardiac arrest used a mechanical chest compression device during advanced CPR, which enabled them to deliver ongoing resuscitation during transfer to the PCI laboratory located 20 km away from the scene. Mechanical chest compressions were continued during the primary coronary intervention. The resuscitation, carried out for 2 h and 35 min, and the coronary intervention were successful, as evidenced by the return of spontaneous circulation and by the fact that, after a short rehabilitation, the patient was discharged home with a favorable neurological outcome. Our case can serve as an example for the effective and safe use of a mechanical compression device during primary coronary intervention.

A comparison of automated and manual sleep staging and respiratory event recognition in a portable sleep diagnostic device with in-lab sleep study.

STUDY OBJECTIVES: The objectives were to develop and validate an algorithm for editing WatchPAT scoring and assess the accuracy in an unselected clinical population as well as age and sex substrata. METHODS: Two hundred sixty-two participants were enrolled to undergo WatchPAT simultaneously with in-lab polysomnography (PSG) recordings for developing (n = 30), optimizing (n = 62), and validating (n = 170) an algorithm to review and edit respiratory events and sleep architecture of WatchPAT recordings, which was based on visual inspection of WatchPAT signals. Apnea-hypopnea index (AHI) and sleep indices were compared with PSG-derived and automated WatchPAT indices. RESULTS: Although estimation of total sleep time (TST) was comparable between automated and manual algorithm, estimation of rapid eye movement (REM) sleep time was markedly improved with manual editing from 0.48, 23.0 min (-43.9 to 89.8) to 0.64, 18.3 min (-32.6 to 69.1) (correlation with PSG, mean difference [reference range] from PSG, respectively). Manual scoring also improved correlation and agreement with PSG AHI from 0.65, 2.5 events/h (-24.0 to 28.9) to 0.81, -4.5 events/h (-22.5 to 13.6) as well as concordance for categorical agreement of sleep-disordered breathing severity and concordance for detecting severe REM-related sleep-disordered breathing. Interscorer reliabilities were excellent for TST and AHI, while good for REM sleep time. The automated algorithm performed better in younger than in older patients, while performed similarly between men and women with respect to concordance statistics. The manual algorithm markedly improved concordances more in older patients and women than in their counterparts. CONCLUSIONS: Our manual editing algorithm improves correlation and agreement with PSG-derived sleep and breathing indices. Sex and age influence the accuracy of automated analysis and the performance of manual editing on AHI concordance.

Handling of Ventricular Fibrillation in the Emergency Setting.

Ventricular fibrillation (VF) and sudden cardiac death (SCD) are predominantly caused by channelopathies and cardiomyopathies in youngsters and coronary heart disease in the elderly. Temporary factors, e.g., electrolyte imbalance, drug interactions, and substance abuses may play an additive role in arrhythmogenesis. Ectopic automaticity, triggered activity, and reentry mechanisms are known as important electrophysiological substrates for VF determining the antiarrhythmic therapies at the same time. Emergency need for electrical cardioversion is supported by the fact that every minute without defibrillation decreases survival rates by approximately 7%-10%. Thus, early defibrillation is an essential part of antiarrhythmic emergency management. Drug therapy has its relevance rather in the prevention of sudden cardiac death, where early recognition and treatment of the underlying disease has significant importance. Cardioprotective and antiarrhythmic effects of beta blockers in patients predisposed to sudden cardiac death were highlighted in numerous studies, hence nowadays these drugs are considered to be the cornerstones of the prevention and treatment of life-threatening ventricular arrhythmias. Nevertheless, other medical therapies have not been proven to be useful in the prevention of VF. Although amiodarone has shown positive results occasionally, this was not demonstrated to be consistent. Furthermore, the potential proarrhythmic effects of drugs may also limit their applicability. Based on these unfavorable observations we highlight the importance of arrhythmia prevention, where echocardiography, electrocardiography and laboratory testing play a significant role even in the emergency setting. In the following we provide a summary on the latest developments on cardiopulmonary resuscitation, and the evaluation and preventive treatment possibilities of patients with increased susceptibility to VF and SCD.

The Efficacy of Low-Level Continuous Positive Airway Pressure for the Treatment of Snoring.

STUDY OBJECTIVES: To assess effects of low-level continuous positive airway pressure (CPAP) on snoring in habitual snorers without obstructive sleep apnea (OSA). METHODS: A multicenter prospective in-laboratory reversal crossover intervention trial was conducted between September 2013 and August 2014. Habitual snorers were included if they snored (inspiratory sound pressure level ≥ 40 dBA) for ≥ 30% all sleep breaths on a baseline sleep study (Night 1), and if significant OSA and daytime somnolence were absent. Included participants then underwent a CPAP titration study at 2, 4, or 6 cm H2O (Night 2) to examine snoring responses to step-increases in nasal pressure, a treatment night at optimal pressure (Night 3), followed by baseline night (Night 4). At each pressure, snoring intensity was measured on each breath. Snoring frequency was quantified as a percentage of sleep breaths at thresholds of 40, 45, 50, and 55 dBA. Sleep architecture and OSA severity were characterized using standard measurements. RESULTS: On baseline sleep studies, participants demonstrated snoring at ≥ 40 dBA on 53 ± 3% and ≥ 45 dBA on 35 ± 4% of breaths. Snoring frequency decreased progressively as nasal pressure increased from 0 to 4 cm H2O at each threshold, and plateaued thereafter. CPAP decreased snoring frequency by 67% and 85% at 40 and 45 dBA, respectively. Intervention did not alter sleep architecture and sleep apnea decreased minimally. CONCLUSIONS: Low-level CPAP below the range required to treat OSA diminished nocturnal snoring, and produced uniform reduction in nightly noise production below the World Health Organization's limit of 45 dBA. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT01949584.