Effect of the NLRP3 inflammasome on increased hypoxic ventilation response after CIH exposure in mice.

BACKGROUND: Chronic intermittent hypoxia (CIH) increases the hypoxic ventilation response (HVR). The downstream cytokine IL-1ß of the NLRP3 inflammasome regulates respiration by acting on the carotid body (CB) and neurons in the respiratory center, but the effect of the NLRP3 inflammasome on HVR induced by CIH remains unclear. OBJECTIVE: To investigate the effect of NLRP3 on the increased HVR and spontaneous apnea events and duration induced by CIH, the expression and localization of NLRP3 in the respiratory regulatory center of the rostral ventrolateral medulla (RVLM), and the effect of CIH on the activation of the NLRP3 inflammasome in the RVLM. METHODS: Eighteen male, 7-week-old C57BL/6 N mice and eighteen male, 7-week-old C57BL/6 N NLRP3 knockout mice were randomly divided into CON-WT, CON-NLRP3-/-, CIH-WT and CIH-NLRP3-/- groups. Respiratory changes in mice were continuously detected using whole-body plethysmography. The expression and localization of the NLRP3 protein and the formation of apoptosis-associated speck-like protein containing CARD (ASC) specks were detected using immunofluorescence staining. RESULTS: NLRP3 knockout reduced the increased HVR and the incidence and duration of spontaneous apnea events associated with CIH. The increase in HVR caused by CIH partially recovered after reoxygenation. After CIH, NLRP3 inflammasome activation in the RVLM, which is related to respiratory regulation after hypoxia, increased, which was consistent with the trend of the ventilation response. CONCLUSION: The NLRP3 inflammasome may be involved in the increase in the HVR and the incidence and duration of spontaneous apnea induced by CIH. NLRP3 inhibitors may help reduce the increase in the HVR after CIH, which is important for ensuring sleep quality at night in patients with obstructive sleep apnea.

Physiological responses during static apnoea efforts in elite and novice breath-hold divers before and after two weeks of dry apnoea training.

This study examined the effect of breath-hold (BH) training on apnoeic performance in novice BH divers (NBH:n = 10) and compared them with data from elite BH divers (EBH:n = 11). Both groups performed 5-maximal BHs (PRE). The NBH group repeated this protocol after two weeks of BH training (POST). The NBH group during BH efforts significantly increased red blood cell concentration (4.56 ± 0.16Mio/µl) by 5.06%, hemoglobin oxygen saturation steady state duration (110.32 ± 29.84 s) by 15.48%, and breath-hold time (BHT:144.19 ± 47.35 s) by 33.77%, primarily due to a 59.70% increase in struggle phase (71.85 ± 30.89 s), in POST. EBH group exhibited longer BHT (283.95 ± 36.93 s) and struggle-phase (150.10 ± 34.69 s) than NBH (POST). Elite divers recorded a higher peak MAP (153.18 ± 12.28 mmHg) compared to novices (PRE:123.70 ± 15.65 mmHg, POST:128.30 ± 19.16 mmHg), suggesting that a higher peak MAP is associated with a better BHT. The concurrent abrupt increase of diaphragmatic activity and MAP, seen only in the EBH group, suggests a potential interaction. Additionally, apnoea training increases red blood cells concentration in repeated apnoea efforts and increases BH stamina.

Apnea management during WATCHMAN device deployment with apneic oxygenation: A case report of three cases.

WATCHMAN is a percutaneous left atrial appendage closure device that is implanted in patients who are unsuitable for anticoagulation therapy for atrial fibrillation. During WATCHMAN implantation, inducing apnea in the patient is preferable to allow stable deployment. We present three cases in which apneic oxygenation was employed to maintain oxygenation during apnea, and oxygen reserve index (ORiTM) was measured to evaluate its safety and efficacy. Oxygen was administered continuously via the endotracheal tube during apnea. During all four apneic events in three patients (mean duration of 356 seconds), the ORi values maintained above 0.24, which is generally considered the threshold of partial pressure of arterial oxygen (PaO2) > 100 mmHg. Transcutaneous oxygen saturation and PaO2 remained above 99% and 300 mmHg, respectively. There were no respiratory or circulatory complications during or after the surgery.

Sudden Unexpected Death in Epilepsy and Respiratory Defects in a Mouse Model of DEPDC5-Related Epilepsy.

OBJECTIVES: DEPDC5 is a common causative gene in familial focal epilepsy with or without malformations of cortical development. Its pathogenic variants also confer a significantly higher risk for sudden unexpected death in epilepsy (SUDEP), providing opportunities to investigate the pathophysiology intersecting neurodevelopment, epilepsy, and cardiorespiratory function. There is an urgent need to gain a mechanistic understanding of DEPDC5-related epilepsy and SUDEP, identify biomarkers for patients at high risk, and develop preventive interventions. METHODS: Depdc5 was specifically deleted in excitatory or inhibitory neurons in the mouse brain to determine neuronal subtypes that drive epileptogenesis and SUDEP. Electroencephalogram (EEG), cardiac, and respiratory recordings were performed to determine cardiorespiratory phenotypes associated with SUDEP. Baseline respiratory function and the response to hypoxia challenge were also studied in these mice. RESULTS: Depdc5 deletion in excitatory neurons in cortical layer 5 and dentate gyrus caused frequent generalized tonic-clonic seizures and SUDEP in young adult mice, but Depdc5 deletion in cortical interneurons did not. EEG suppression immediately following ictal offset was observed in fatal and non-fatal seizures, but low amplitude rhythmic theta frequency activity was lost only in fatal seizures. In addition, these mice developed baseline respiratory dysfunction prior to SUDEP, during which ictal apnea occurred long before terminal cardiac asystole. INTERPRETATION: Depdc5 deletion in excitatory neurons is sufficient to cause DEPDC5-related epilepsy and SUDEP. Ictal apnea and respiratory dysregulation play critical roles in SUDEP. Our study also provides a novel mouse model to investigate the underlying mechanisms of DEPDC5-related epilepsy and SUDEP. ANN NEUROL 2023;94:812-824.

Rebounds of sevoflurane concentration during simulated trigger-free pediatric and adult anesthesia.

BACKGROUND: In trigger-free anesthesia a volatile anesthetic concentration of 5 parts per million (ppm) should not be exceeded. According to European Malignant Hyperthermia Group (EMHG) guideline, this may be achieved by removing the vapor, changing the anesthetic breathing circuit and renewing the soda lime canister followed by flushing with O2 or air for a workstation specific time. Reduction of the fresh gas flow (FGF) or stand-by modes are known to cause rebound effects. In this study, simulated trigger-free pediatric and adult ventilation was carried out on test lungs including ventilation maneuvers commonly used in clinical practice. The goal of this study was to evaluate whether rebounds of sevoflurane develop during trigger-free anesthesia. METHODS: A Dräger® Primus® was contaminated with decreasing concentrations of sevoflurane for 120 min. Then, the machine was prepared for trigger-free anesthesia according to EMHG guideline by changing recommended parts and flushing the breathing circuits using 10 or 18 l⋅min- 1 FGF. The machine was neither switched off after preparation nor was FGF reduced. Simulated trigger-free ventilation was performed with volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) including various ventilation maneuvers like pressure support ventilation (PSV), apnea, decreased lung compliance (DLC), recruitment maneuvers, prolonged expiration and manual ventilation (MV). A high-resolution ion mobility spectrometer with gas chromatographic pre-separation was used to measure sevoflurane in the ventilation gas mixture in a 20 s interval. RESULTS: Immediately after start of simulated anesthesia, there was an initial peak of 11-18 ppm sevoflurane in all experiments. The concentration dropped below 5 ppm after 2-3 min during adult and 4-18 min during pediatric ventilation. Other rebounds of sevoflurane > 5 ppm occurred after apnea, DLC and PSV. MV resulted in a decrease of sevoflurane < 5 ppm within 1 min. CONCLUSION: This study shows that after guideline-compliant preparation for trigger-free ventilation anesthetic machines may develop rebounds of sevoflurane > 5 ppm during typical maneuvers used in clinical practice. The changes in rate and direction of internal gas flow during different ventilation modes and maneuvers are possible explanations. Therefore, manufacturers should provide machine-specific washout protocols or emphasize the use of active charcoal filters (ACF) for trigger-free anesthesia.

Effect of reverse Trendelenburg position and positive pressure ventilation on safe non-hypoxic apnea period in obese, a randomized-control trial.

PURPOSE: There is an elevated incidence of hypoxemia during the airway management of the morbidly obese. We aimed to assess whether optimizing body position and ventilation during pre-oxygenation allow a longer safe non-hypoxic apnea period (SNHAP). METHODS: Fifty morbidly obese patients were recruited and randomized for this study. Patients were positioned and preoxygenated for three minutes in the ramp position associated with spontaneous breathing without additional CPAP or PEEP (RP/ZEEP group) or in the reverse Trendelenburg position associated with pressure support ventilation mode with pressure support of 8 cmH2O and an additional 10 cmH2O of PEEP while breathing spontaneously (RT/PPV group) according to randomization. RESULTS: The SNHAP was significantly longer in the RT/PPV group (258.2 (55.1) vs. 216.7 (42.3) seconds, p = 0.005). The RT/PPV group was also associated to a shorter time to obtain a fractional end-tidal oxygen concentration (FEtO2) of 0.90 (85.1(47.8) vs 145.3(40.8) seconds, p < 0.0001), a higher proportion of patients that reached the satisfactory FEtO2 of 0.90 (21/24, 88% vs. 13/24, 54%, p = 0.024), a higher FEtO2 during preoxygenation (0.91(0.05) vs. 0.89(0.01), p = 0.003) and a faster return to 97% oxygen saturation after ventilation resumption (69.8 (24.2) vs. 91.4 (39.2) seconds, p = 0.038). CONCLUSION: In the morbidly obese population, RT/PPV, compared to RP/ZEEP, lengthens the SNHAP, decreases the time to obtain optimal preoxygenation conditions, and allows a faster resuming of secure oxygen saturation. The former combination allows a more significant margin of time for endotracheal intubation and minimizes the risk of hypoxemia in this highly vulnerable population. TRIAL REGISTRATION: NCT02590406, 29/10/2015.

The effect of capnography on the incidence of hypoxia during sedation for EGD and colonoscopy in mildly obese patients: a randomized, controlled study.

BACKGROUND: By continually monitoring end-tidal carbon dioxide concentrations, capnography can detect abnormal ventilation or apnoea early. This randomized, controlled study explored the effect of early intervention with capnography on the incidence of hypoxia in mildly obese patients undergoing sedation for esophagogastroduodenoscopy (EGD) and colonoscopy. METHODS: This is a single-center, randomized, single-blind, parallel-assignment, controlled trial. Mildly obese patients (28 kg/m2 ≤ BMI < 40 kg/m2) undergoing sedation for EGD and colonoscopy were randomly assigned to either the standard or capnography group. Standard cardiopulmonary monitoring equipment was used in both groups, and additional capnography was performed in the capnography group. In the event of inadequate alveolar ventilation during sedation, five interventions were administered in sequence (a-e) : a: increasing oxygen flow (5 L/min); b: a chin lift or jaw thrust maneuver; c: placement of the nasopharyngeal airway and chin lift; d: mask positive-pressure ventilation, and e: ventilator-assisted ventilation with tube insertion. The primary outcome was the incidence of hypoxia (SpO2 < 90%, ≥ 10 s) in each group. The secondary outcomes included the incidence of severe hypoxia (SpO2 ≤ 85%), subclinical respiratory depression (90% ≤ SpO2 < 95%), interventions, minimum SpO2 during operation, patient satisfaction, endoscopist satisfaction, and other adverse events of anesthesia sedation. RESULTS: 228 patients were included (capnography group = 112; standard group = 113; three patients were excluded) in this study. The incidence of hypoxia was significantly lower in the capnography group than in the standard group (13.4% vs. 30.1%, P = 0.002). Subclinical respiratory depression in the capnography group was higher than that of the standard group (30.4% vs. 17.7%, P = 0.026). There was only a 5.4% incidence of severe hypoxia in the capnography group compared with 14.2% in the standard group (P = 0.026). During sedation, 96 and 34 individuals in the capnography and standard groups, respectively, underwent the intervention. There was a statistically significant difference (P < 0.0001) in the number of the last intraoperative intervention between the two groups ( a:47 vs. 1, b:46 vs. 26, c:2 vs. 5, d:1 vs. 2, e:0 vs. 0 ). No significant differences were found between the two groups in terms of minimum SpO2 during operation, patient satisfaction, or endoscopist satisfaction rating. There was no statistically significant difference in adverse events of anesthesia sedation between the two groups. CONCLUSION: Capnography during sedation for EGD and colonoscopy allows for the detection of apnea and altered breathing patterns in mildly obese patients before SpO2 is reduced. Effective intervention measures are given to patients within this time frame, which reduces the incidence of hypoxia and severe hypoxia in patients. TRIAL REGISTRATION: Ethical approval was granted by the Medical Ethics Committee (Chairperson Professor Tian Hui) of Qilu Hospital, Shandong University ((Ke) Lun Audit 2021 (186)) on 15/07/2021. The study was registered ( https://www.chictr.org.cn ) on 23/10/2021(ChiCTR2100052234). Designed and reported using CONSORT statements.

Long-term follow-up on the effects of sodium oxybate on daytime sleepiness and sleep architecture in patients with narcolepsy type 1. / Efecto a largo plazo del oxibato de sodio en la somnolencia diurna y en la estructura del sueño en pacientes con narcolepsia de tipo 1.

INTRODUCTION: Sodium oxybate (SXB) was administered for the first time in 1979 in 16 patients with narcolepsy with cataplexy (NT1) that improved up to 20 months. AIMS: To evaluate the effect of SXB on daytime sleepiness and sleep architecture by video-polysomnography in a sample of 23 NT1 adult patients (13 men, 10 females) treated up to three years. Additional goal was to study the presence of sleep comorbidities. PATIENTS AND METHODS: NT1 patients were diagnosed according to International Classification of Sleep Disorders, third edition. We conducted a longitudinal observational study and a video-polysomnography comparing the sleep parameters of patients treated with an initial nocturnal dose of 4.5 g of SXB after six months (FU-1), one year (FU-2) and three years (FU-3) of uninterrupted treatment. Video-polysomnography parameters were analyzed including apnea-hypopnea and periodic leg movements indexes. RESULTS: Patients were HLA-DQB1*06:02 positive except a familial case. Thirteen patients (56%) discontinued SXB treatment over the three-year of the study. The two-nightly doses has been one of the reason for discontinuing treatment as well as insufficient compliance, mild or severe side effects, comorbidities and pregnancy. We found significant differences at FU-2 in sleep structure with an increased in stage N2 (p < 0.03) and a higher periodic leg movements index (p < 0.01). At FU-3 we found significant differences in sleep structure with an increase in stage N1 (p = 0.03) and in comorbidities (periodic leg movements and apnea-hypopnea indexes). There was not significant change on daytime sleepiness during the study. CONCLUSIONS: SXB was administered in low-medium doses. Two-nightly doses and sleep fragmentation linked to sleep comorbidities at long-term lead to drug withdrawal.

TITLE: Efecto a largo plazo del oxibato de sodio en la somnolencia diurna y en la estructura del sueño en pacientes con narcolepsia de tipo 1.Introducción. El oxibato de sodio (SXB) se utilizó en 1979 en 16 enfermos con narcolepsia-cataplejía (NT1) que mejoraron tras 20 meses de tratamiento. Objetivos. Evaluar el efecto del SXB en la somnolencia diurna y en la estructura del sueño mediante videopolisomnografía en una muestra de 23 enfermos de NT1 (13 hombres y 10 mujeres) tratados durante tres años. Investigamos adicionalmente la presencia de comorbilidad. Pacientes y métodos. Diagnosticamos a los enfermos de acuerdo con la Clasificación Internacional de Trastornos del Sueño, tercera edición. Realizamos un estudio longitudinal, observacional y de videopolisomnografía, comparando los parámetros de sueño y los índices de apnea-hipopnea y de movimientos periódicos de las piernas de los enfermos, tratados con una dosis nocturna inicial de 4,5 g de SXB al cabo de seis meses (C-1), un año (C-2) y tres años (C-3) de tratamiento ininterrumpido. Resultados. Todos los enfermos eran HLA-DQB1*06:02 positivos, excepto un caso familiar. Trece enfermos (56%) interrumpieron el tratamiento debido a las dos tomas nocturnas, así como a la presencia de efectos secundarios, comorbilidad y embarazo. Encontramos diferencias significativas en C-2 en la estructura del sueño con aumento del estadio N2 (p < 0,03) y del índice de movimientos periódicos de las piernas (p < 0,01). En el control C-3 encontramos diferencias significativas en la estructura del sueño con aumento del estadio N1 (p = 0,03), y de los índices de movimientos periódicos de las piernas y de apnea-hipopnea. Conclusiones. El SXB se administró en dos dosis nocturnas, lo que, unido a la fragmentación del sueño y a la aparición de comorbilidades, condujo a la interrupción del tratamiento a largo plazo.

[A sub-merged arrhythmia... and an up-emerged female swimmer. A case of atrioventricular nodal reentry tachycardia in a young female swimmer surfacing from dynamic apnea]. / Un'aritmia sommersa e una nuotatrice riemersa. Un caso di tachicardia sopraventricolare da rientro nodale in una giovane nuotatrice in riemersione dall'apnea dinamica.

The irrefutable benefits of physical activity as a tool for the prevention and treatment of several clinical conditions, including cardiovascular diseases, are nowadays widely recognized. However, physical exercise may trigger adverse events in subjects with underlying heart disease, often undiagnosed and asymptomatic. It is fundamental to consider that various sports disciplines have peculiar and specific physiological and metabolic adaptations, and it is essential to consider the individual profile of the subject, including gender. We report the case of an agonistic female swimmer with a history of tachycardia heartbeat when resurfacing from dynamic apnea, in whom a diagnosis of atrioventricular nodal reentrant tachycardia was made. This case report provides practical evidence of the importance of a personalized approach, in both individual sex- and sport-specific terms, to optimize the diagnostic and therapeutic pathways.

Análisis de causas atribuidas a "BRUE" entre los años 2017 a 2020 / Analysis of etiologies attributed to "BRUE" between the years 2017 to 2020

El término BRUE describe un evento en un lactante menor, repentino, breve, ya resuelto y sólo aplica cuando no existe una explicación para este episodio. Es escasa la literatura nacional e internacional sobre el estudio etiológico en BRUE. Objetivos: Caracterizar lactantes con episodio de BRUE y hacer un análisis etiológico. Métodos: Estudio retrospectivo, descriptivo lactantes hospitalizados por BRUE. Resultados: Se encontraron 50 lactantes con BRUE, la mayoría de ellos presentó un solo evento y ninguno requirió reanimación cardiopulmonar. Las características principales de los eventos fueron apnea, cianosis y tono disminuido. Las etiologías encontradas, más habituales, fueron reflujo gastro-esofágico, infección respiratoria, mala técnica alimentaria y crisis epilépticas. La evaluación clínica fue el principal elemento diagnóstico. Discusión: Nuestro análisis etiológico concuerda con la literatura nacional e internacional. La anamnesis y examen físico son la principal herramienta diagnóstica. Es fundamental contar con guías, adaptadas a la realidad nacional y local, que dirijan el estudio de lactantes con BRUE.

BRUE is an event occurring in an infant when the observer reports a sudden, brief, and now-resolved episode. BRUE is a diagnosis of exclusion and is used only when there is no explanation for the event after conducting an appropriate history and physical examination. There is little literature on the etiological study in BRUE. Objectives: To characterize infants with a BRUE episode and to carry out an etiological analysis. Methods: A retrospective study including infants who have experienced a BRUE between the years 2017 to 2020. Results: 50 infants with BRUE, most of them presented a single event and none required cardiopulmonary resuscitation. The main characteristics of the events were apnea, cyanosis and decreased tone. The most common etiologies found were gastroesophageal reflux, respiratory infection, poor feeding technique, and seizures. History and physical examination are the fundamental diagnostic tools. Discussion: Our etiological analysis agrees with the national and international literature. The clinical evaluation was the main diagnostic tool. It is essential to create local guidelines for the evaluation investigation and management of infants with BRUE.

Isolated ictal apnea in neonatal age: Clinical features and treatment options. A systematic review.

BACKGROUND: Among autonomic seizures apnea still represent a challenge for physicians, and it might constitute the only isolated sign of neurological disorder. The aim of this review is to describe ictal apnea (IA) and its treatment options. METHODS: MeSH and keywords were combined: "neonatal seizures", "ictal neonatal apnea", "apneic seizures". All identified papers were screened for neonatal seizures titles and abstracts; case reports describing patients with IA as an isolated manifestation of neonatal seizures were included. RESULTS: Eight studies including a total of 13 patients were identified. Among 13 patients, 9 were full-term and 4 were preterm neonates. All patients developed IA within twenty-one days from birth. Etiologies of seizures included: temporal lobe hemorrhage (3 pt), occipital stroke (1 pt), hypoxic-ischemic encephalopathy (HIE) (1 pt), parasagittal injury (1 pt), 18 trisomy (2 pt). Five patients showed no structural CNS alterations. Ten patients had the ictal focus localized in the temporal lobe; the occipital lobe was the second most involved site. Phenobarbital was administered in 76 % of cases with IA (10 pt), and showed efficacy in 74 % of them; 2 required a second anti-epileptic drug (AED) to reach seizure control. Levetiracetam was given to 11 % (2 pt) successfully. Only one was treated with midazolam and one did not require any anticonvulsant. CONCLUSIONS: Not homogeneous data and paucity of isolated IA currently reported in literature limits agreement about definition, management and treatment of entity, however an ever-growing attention is needed, and EEG/aEEG, despite their possible controversies in the diagnosis, should be performed to investigate unexplained forms of apnea.

Efficacy of capnographic and bispectral index monitoring on trans-oral therapeutic endoscopy: A prospective observational study.

BACKGROUND AND AIM: Oral therapeutic and invasive endoscopy requires deep sedation to reduce patient distress due to prolonged examination and procedures. The usefulness of capnography and bispectral index (BIS) monitoring in the early hypoxia detection in oral therapeutic and invasive endoscopy has yet to be evaluated. This study aimed to investigate the clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures. METHODS: This is a prospective observational study. Trans-oral non-intubated therapeutic and/or invasive endoscopic procedures were performed with conventional monitoring (pulse oximetry, pulse, and blood pressure) as well as additional monitoring (BIS and end-tidal CO2 concentration). Hypoxia is defined as oxygen saturation of <90% that lasts >15 s. The clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures were investigated with the risk factors for hypoxia in each patient. RESULTS: Patients with hypoxia had significantly more apneas detected using capnography than other patients. The multivariate analysis revealed the detected apnea by capnography as an independent risk factor for hypoxia (odds ratio: 3.48[95% confidence interval: 1.24-9.78], P = 0.02). The BIS was not significantly different as a risk factor for hypoxia; however, per-event analysis revealed significantly decreased BIS values over time in 3 min before hypoxic events. CONCLUSIONS: Apnea detected by capnography was an independent predictor of hypoxia. The BIS value was not associated with hypoxia events; however, it showed a significant downward trend before hypoxia events.

Association between nocturnal oxygen desaturation and ischaemic stroke outcomes.

CLINICAL RATIONALE FOR THE STUDY: This study aimed to assess the association between nocturnal hypoxemia and early acute ischaemic stroke (AIS) outcomes in patients without oxygen supplementation. MATERIAL AND METHODS: One hundred and six AIS patients consecutively admitted to the stroke unit were included in this study. Baseline demographic and medical data and arterial blood saturation (SpO2) measurements during night-sleep (from 10pm to 6am) were examined for their association with stroke outcomes, including the National Institutes of Health Stroke Scale (NIHSS) score on the 7th day or differences between the NIHSS score on the 1st day and the 7th day after stroke onset. Measurements of SpO2 were made using a pulse oximeter of the Spacelabs Medical Inc. (USA) monitoring system, and the number of apnoea episodes and their duration were recorded by ECG Holter with respiration monitoring (CardioMem®, Getamed, GE). RESULTS: The study showed that age (Spearman's r = 0.207, p = 0.033) and parameters attributable to anaemia (RBC r = -0.205, p = 0.035, Hb r = -0.225, p = 0.02 and HCT r = -0.196, p = 0.044), atrial fibrillation and ischaemic changes in both brain hemispheres (p = 0.023 and 0.01, respectively) were correlated with the study outcomes. In terms of saturation parameters, we demonstrated that the 'total desaturation burden' (i.e. [100% minus actual measured SpO2%] x apnoea duration) and multiple apnoeas of longer than 20 seconds were correlated with worse functional outcomes. Measures of shorter desaturation episodes (i.e. SpO2 oxygen desaturation index (ODI) at 3% and 4%, and time-weighted desaturations below the determined thresholds (SpO2 from 95% to 85%) demonstrated non-significant associations with the study outcomes. CONCLUSIONS AND CLINICAL IMPLICATIONS: This study demonstrated that long-lasting desaturation episodes during the night, depicted by the 'total desaturation burden', were correlated with worse functional outcomes in AIS, while measures of shorter desaturation episodes were not correlated. In future clinical trials, indications for oxygen supplementation should include the methodology of personalised medicine and introduce individual approaches based on specially formulated, novel multifactorial algorithms.

High prevalence of patent foramen ovale in recreational to elite breath hold divers.

OBJECTIVES: During apnea diving, a patent foramen ovale may function as a pressure relief valve under conditions of high pulmonary pressure, preserving left-ventricular output. Patent foramen ovale prevalence in apneic divers has not been previously reported. We aimed to determine the prevalence of patent foramen ovale in apneic divers compared to non-divers. DESIGN: Cross sectional. METHODS: Apnea divers were recruited from a training camp in Cavtat, Croatia and the diving community of Split, Croatia. Controls were recruited from the population of Split, Croatia and Eugene, Oregon, USA. Participants were instrumented with an intravenous catheter and underwent patent foramen ovale screening utilizing transthoracic saline contrast echocardiography. Appearance of microbubbles in the left heart within 3 cardiac cycles indicated the presence of patent foramen ovale. Lung function was measured with spirometry. Comparison of patent foramen ovale prevalence was conducted using chi-square analysis, p < .05. RESULTS: Apnea divers had a significantly higher prevalence of patent foramen ovale (19 of 36, 53%) compared to controls (9 of 36, 25%) (X2 (1, N = 72) = 5.844, p = .0156). CONCLUSIONS: Why patent foramen ovale prevalence is greater in apnea divers remains unknown, though hyperbaria during an apnea dive results in a translocation of blood volume centrally with a concomitant reduction in lung volume and alveolar hypoxia during ascent results in hypoxic pulmonary vasoconstriction. These conditions increase pulmonary arterial pressure, increasing right-atrial pressure allowing for right-to-left blood flow through a patent foramen ovale which may be beneficial for preserving cardiac output and reducing capillary hydrostatic forces.

Association between Self-Perceived Periodic Limb Movement during Sleep and Excessive Daytime Sleepiness Depend on Restless Leg Symptoms in Korean Adolescents.

Although periodic limb movement during sleep (PLMS) and restless legs syndrome (RLS) are common in children and adolescents, they are relatively overlooked as a target of treatment. PLMS has been evaluated as having a lower clinical significance than RLS. This study examined the relationship of socio-behavioral factors of PLMS in Korean adolescents and checked whether PLMS is associated with excessive daytime sleepiness (EDS), depending on whether restless legs symptoms accompany it. In a cross-sectional study, 25,789 adolescents between 12 and 18 years of age (15.76 ± 1.73 years; female 51.49%) were evaluated using an online survey. Various self-report questionnaires were used to assess PLMS and RLS symptoms, EDS, sleep habits, and various socio-behavioral factors. The prevalence of self-perceived PLMS and restless legs symptoms were 903 (3.50%) and 1311 (5.08%), respectively. Of the 1311 participants, 399 had self-perceived PLMS. The odds ratios (ORs) for self-perceived PLMS in participants with restless legs symptoms were: males (OR = 1.528; 95% CI: 1.145-2.040), usually/always experienced apnea apnea (OR, 3.006; 95% CI, 1.954-4.624), increased proneness to Internet addiction (OR = 1.013; 95% CI: 1.001-1.025), sometimes/often consuming coffee (OR = 1.312; 95% CI: 1.015-1.695), EDS (OR = 0.826; 95% CI: 0.488-1.398), and perceived insufficient sleep (OR = 1.143; 95% CI: 0.835-1.565). The male gender, witness apnea, consuming coffee, and being prone to Internet addiction were identified as factors significantly associated with self-perceived PLMS in participants with restless legs symptoms. However, EDS and insufficient sleep were associated with self-perceived PLMS in the absence of restless legs symptoms.

Apnoeic oxygenation with high-flow oxygen for tracheal resection and reconstruction surgery.

BACKGROUND: Tracheal resection and reconstruction are the most effective treatments for tracheal stenosis, but the difficulties are surgery and maintaining ventilation performed on the patient's same airway. High-flow oxygen has begun to be applied to prolong the apnoea time in the tracheal anastomosis period for tracheal resection and reconstruction. This study aims to evaluate the effectiveness of apneic conditions with high-flow oxygen as the sole method of gas exchange during anastomosis construction. METHODS: A prospective study was performed on 16 patients with tracheal stenosis, with ages ranging from 19 to 70, who underwent tracheal resection and reconstruction from April 2019 to August 2020 in 108 Military Central Hospital. During the anastomosis phase using high flow oxygen of 35-40 l.min-1 delivered across the open tracheal with an endotracheal tube (ETT) at the glottis in apnoeic conditions. RESULTS: The mean (SD) apnoea time was 20.91 (2.53) mins. Mean (SD) time anastomosis was 22.9 (2.41) mins. The saturation of oxygen was stable during all procedures at 98-100%. Arterial blood gas analysis showed mean (SD) was hypercapnia and acidosis acute respiratory after 10 mins of apnoea and 20 mins apnoea respectively. However, after 15 mins of ventilation, the parameters are ultimately returned to normal. All 16 patients were extubated early and safely at the end of the operation. There were no complications, such as bleeding, hemothorax, pneumothorax, or barotrauma. CONCLUSION: High-flow oxygen across the open tracheal under apnoeic conditions can provide a satisfactory gas exchange to allow tubeless anesthesia for tracheal resection and reconstruction.

Central Apneas Are More Detrimental in Female Than in Male Patients With Heart Failure.

Background Central apneas (CA) are a frequent comorbidity in patients with heart failure (HF) and are associated with worse prognosis. The clinical and prognostic relevance of CA in each sex is unknown. Methods and Results Consecutive outpatients with HF with either reduced or mildly reduced left ventricular ejection fraction (n=550, age 65±12 years, left ventricular ejection fraction 32%±9%, 21% women) underwent a 24-hour ambulatory polygraphy to evaluate CA burden and were followed up for the composite end point of cardiac death, appropriate implantable cardioverter-defibrillator shock, or first HF hospitalization. Compared with men, women were younger, had higher left ventricular ejection fraction, had lower prevalence of ischemic etiology and of atrial fibrillation, and showed lower apnea-hypopnea index (expressed as median [interquartile range]) at daytime (3 [0-9] versus 10 [3-20] events/hour) and nighttime (10 [3-21] versus 23 [11-36] events/hour) (all P<0.001), despite similar neurohormonal activation and HF therapy. Increased chemoreflex sensitivity to either hypoxia or hypercapnia (evaluated in 356 patients, 65%, by a rebreathing test) was less frequent in women (P<0.001), but chemoreflex sensitivity to hypercapnia was a predictor of apnea-hypopnea index in both sexes. At adjusted survival analysis, daytime apnea-hypopnea index ≥15 events/hour (hazard ratio [HR], 2.70; 95% CI, 1.06-7.34; P=0.037), nighttime apnea-hypopnea index ≥15 events/hour (HR, 2.84; 95% CI, 1.28-6.32; P=0.010), and nighttime CA index ≥10 events/hour (HR, 5.01; 95% CI, 1.88-13.4; P=0.001) were independent predictors of the primary end point in women but not in men (all P>0.05), also after matching women and men for possible confounders. Conclusions In chronic HF, CA are associated with a greater risk of adverse events in women than in men.

Postictal Death Is Associated with Tonic Phase Apnea in a Mouse Model of Sudden Unexpected Death in Epilepsy.

OBJECTIVE: Sudden unexpected death in epilepsy (SUDEP) is an unpredictable and devastating comorbidity of epilepsy that is believed to be due to cardiorespiratory failure immediately after generalized convulsive seizures. METHODS: We performed cardiorespiratory monitoring of seizure-induced death in mice carrying either a p.Arg1872Trp or p.Asn1768Asp mutation in a single Scn8a allele-mutations identified from patients who died from SUDEP-and of seizure-induced death in pentylenetetrazole-treated wild-type mice. RESULTS: The primary cause of seizure-induced death for all mice was apnea, as (1) apnea began during a seizure and continued for tens of minutes until terminal asystole, and (2) death was prevented by mechanical ventilation. Fatal seizures always included a tonic phase that was coincident with apnea. This tonic phase apnea was not sufficient to produce death, as it also occurred during many nonfatal seizures; however, all seizures that were fatal had tonic phase apnea. We also made the novel observation that continuous tonic diaphragm contraction occurred during tonic phase apnea, which likely contributes to apnea by preventing exhalation, and this was only fatal when breathing did not resume after the tonic phase ended. Finally, recorded seizures from a patient with developmental epileptic encephalopathy with a previously undocumented SCN8A likely pathogenic variant (p.Leu257Val) revealed similarities to those of the mice, namely, an extended tonic phase that was accompanied by apnea. INTERPRETATION: We conclude that apnea coincident with the tonic phase of a seizure, and subsequent failure to resume breathing, are the determining events that cause seizure-induced death in Scn8a mutant mice. ANN NEUROL 2021;89:1023-1035.

Amygdala lesions reduce seizure-induced respiratory arrest in DBA/1 mice.

Sudden unexpected death in epilepsy (SUDEP) is the most common cause of death in patients with refractory epilepsy. Human studies and animal models suggest that respiratory arrest is the initiating event leading to death in many cases of SUDEP. It has previously been reported that the onset of apnea can coincide with the spread of seizures to the amygdala, and apnea can be reproduced by electrical stimulation of the amygdala. The aim of the current work was to determine if the amygdala is required for seizure-induced respiratory arrest (S-IRA) in a mouse model of SUDEP. Experiments were performed on DBA/1 mice that have audiogenic seizures with a high incidence of fatal postictal respiratory arrest. Electrolytic lesions of the amygdala significantly reduced the incidence of S-IRA without altering seizures, baseline breathing, or the hypercapnic ventilatory response. These results indicate that the amygdala is a critical node in a pathway to the lower brainstem that is needed for seizures to cause respiratory arrest. SIGNIFICANCE STATEMENT: Sudden unexpected death in epilepsy is the most common cause of mortality in patients with refractory epilepsy, and S-IRA is thought to be important in the pathophysiology in many cases. In a patient with epilepsy, the onset of apnea has been shown to coincide with spread of seizures to the amygdala, and in multiple patients, apnea was induced by stimulation of the amygdala. Here, we show that lesions of the amygdala reduced the incidence of S-IRA and death in a mouse model of SUDEP. These results provide evidence that the amygdala may be a critical node in the pathway by which seizures influence the brainstem respiratory network to cause apnea. This article is part of the Special Issue NEWroscience 2018.