O037 Genioglossus motor control following the return to sleep after brief arousal

Rationale Arousal from sleep has been shown to elicit a prolonged increase in genioglossus muscle activity that persists following the return to sleep and may protect against airway collapse. We hypothesised that this increased genioglossal activity following return to sleep after an arousal is due to persistent firing of inspiratory single motor units (SMUs) recruited during the arousal. Methods 34 healthy participants were studied overnight while wearing a nasal mask/pneumotachograph to measure ventilation and with 4 intramuscular genioglossus SMU electrodes. During stable N2 and N3 sleep, auditory tones were played to induce brief (3-15s) AASM arousals. Ventilation and genioglossus SMUs were quantified for 5 breaths before the tone, during the arousal and for 10 breaths after the return to sleep. Results A total of 1089 tones were played and gave rise to 236 SMUs recorded across arousal and the return to sleep in 20 participants (age 23±4.2 years and BMI 22.5±2.2kg/m2). Ventilation was elevated above baseline during arousal and the first post-arousal breath (p<0.001). The peak firing frequency of expiratory and tonic SMUs was unchanged during arousal and return to sleep, whereas inspiratory modulated SMUs were increased during the arousal and for 4 breaths following the return to sleep (p<0.001). Conclusions The prolonged increase in genioglossus activity that occurs on return to sleep after arousal is a result of persistent activity of inspiratory SMUs. Strategies to elevate inspiratory genioglossus SMU activity may be beneficial in preventing/treating obstructive sleep apnea.

CPAP - The choice of the mask does matter

We present a case of a patient with uncorrected Obstructive Sleep Apnea (OSA) despite good CPAP compliance with an oronasal mask who was referred to our tertiary care multidisciplinary sleep unit. We present here our systematic and comprehensive re-evaluation of the case, accompanied by an image of the polysomnography recordings that exemplify each step in the process, which concludes with a change to nasal CPAP and a transition to BPAP treatment. Keywords: obstructive sleep apnea; CPAP; BPAP; oronasal mask; nasal mask.

Intermittent abdominal pressure ventilation: feasibility and efficacy in neuromuscular disease. A case report

he standard treatment for patients with neuromuscular respiratory failure is non-invasive ventilation (NIV) as non-invasive ventilation support-setting (NVS). NVS is administered through a nasal or face mask and/or mouthpiece with the potential to cause nasal ulcers, discomfort, and/or aesthetic issues, resulting in poor compliance. We reported the observation of a 45-year-old woman with limb-girdle muscular dystrophy (LGMD), secondary to Dysferlin deficiency, who was on NVS since 2017 for nocturnal hypoventilation. In 2018, despite nocturnal ventilation, due to weight gain and daytime hypoventilation, a nasal mask was introduced. We initiated daytime intermittent abdominal pressure ventilation (IAPV) to mitigate cosmetic problems, improving in pO2 and decreasing in pCO2 versus baseline (52>84 mmHg, 46>33 mmHg respectively) at 6 (85 mmHg, 42 mmHg) and 18 months (93 mmHg, 38 mmHg), respectively. IAPV was effective, safe, and well-tolerated in our patients who did not tolerate standard daytime NVS with the known interface.

Interface leakage during neonatal CPAP treatment: a randomised, cross-over trial

ObjectiveTo determine leakage for two neonatal continuous positive airway pressure (CPAP) interfaces and evaluate leak-corrective manoeuvres.DesignThe ToNIL (Trial of NCPAP Interface Leakage) study was a randomised, clinical, cross-over trial with data collection between August 2018 and October 2019. The primary outcome was blinded to the treating staff.SettingOne secondary, 8-bed neonatal intensive care unit (NICU) and three larger (>15 beds), academic NICU referral centres.PatientsNewborn infants with CPAP were screened (n=73), and those with stable spontaneous breathing, low oxygen requirement, postmenstrual age (PMA) over 28 weeks and no comorbidities were eligible. In total, 50 infants were included (median PMA 33 completed weeks).InterventionsLeakage was measured for both prongs and nasal mask, before and after leak-corrective manoeuvres. Interface application was performed in a randomised order by a nurse, blinded to the measured leakage.Main outcome measures30 s average leakage, measured in litres per minute (LPM).ResultsAnalyses showed a significantly lower leakage (mean difference 0.86 LPM, 95% CI 0.07 to 1.65) with prongs (median 2.01 LPM, IQR 1.00–2.80) than nasal mask (median 2.45 LPM, IQR 0.99–5.11). Leak-corrective manoeuvres reduced leakage significantly for both prongs (median 1.22 LPM, IQR 0.54–1.87) and nasal mask (median 2.35 LPM, IQR 0.76–4.75).ConclusionsLarge leakages were common for both interfaces, less with prongs. Simple care manoeuvres reduced leakage for both interfaces. This is the first report of absolute leakage for nasal interfaces and should encourage further studies on leakage during CPAP treatment.

A Study on the Efficacy and Safety of a New Endoscopic Nasal Mask for Intravenous Anaesthesia With Respiratory Retention: a Randomized Controlled Trial

Background: General anaesthesia is the most common choice for day surgery, and a laryngeal mask airway is the most commonly used airway management method in general anaesthesia. Many of the complications of laryngeal mask airways are not conducive to a rapid recovery and discharge. The main purpose of this study was to verify the effectiveness and safety of a new endoscopic nasal mask for anaesthesia for a short surgery.Methods: This is a randomized controlled study of 96 patients who were scheduled to undergo hysteroscopy, breast mass resection or great saphenous vein lesion resection. They were randomly divided into two groups. After entering the operating room, 48 patients in the control group were treated with LMA-assisted ventilation, and 48 patients in the experimental group were subjected to assisted ventilation with the new endoscopic nasal mask. Both groups were given dexmedetomidine combined with sufentanil, propofol, dexamethasone, parecoxib sodium, dezocine and ramosetron to complete the intravenous general anaesthesia.The main observation indexes included the occurrence of hypoxemia (SpO2<90%) after anaesthesia induction; the occurrence of hypercapnia (PetCO2>50 mmHg) due to respiratory depression and changes in the PaO2 and PaCO2 values in the arterial blood gas analysis (ABG) results.Results: The occurrence of hypoxemia (SPO2<90%) in the experimental group and the control group was not significantly different (P>0.05). The occurrence of hypercapnia (PetCO2>50 mmHg) in the experimental group was significantly reduced compared to that in the control group (P<0.05), and the difference was statistically significant. According to the results of the preoperative and postoperative arterial blood gas analysis, there was no statistically significant difference in PaO2 and PaCO2 between the two groups (P>0.05). Conclusion: Both methods are safe and effective for anaesthesia during a short operation. The new endoscopic nasal mask can quickly and effectively provide effective ventilation . It is convenient for anaesthesia airway management for clinical short day surgery.Trial registration: Trial Registration: www.chictr.org.cn; registration no.: ChiCTR2000032548; date of registration: 3rd May 2020

Odor Canopy: A Method for Comfortable Odorant Delivery in MRI

Functional magnetic resonance imaging (fMRI) has become the leading method for measuring the human brain response to sensory stimuli. However, olfaction fMRI lags behind vision and audition fMRI for two primary reasons: First, the olfactory brain areas are particularly susceptible to imaging artefacts, and second, the olfactory stimulus is particularly difficult to control in the fMRI environment. A component of the latter is related to the odorant-delivery human-machine interface, namely the point where odorants exit the dispensing apparatus to reach at the nose. Previous approaches relied on either nasal cannulas or nasal masks, each associated with particular drawbacks and discomforts. Here we provide detailed descriptions and instructions for transforming the MRI head-coil into an olfactory microenvironment, or odor canopy, where odorants can be switched on and off in less than 150 milliseconds without cannula or mask. In a proof-of-concept experiment we demonstrate that odor canopy provides for clearly dissociable odorant presence and absence, with no non-olfactory cues. Moreover, we find that odor canopy is rated more comfortable than nasal-mask, and we demonstrate that using odor canopy in the fMRI generates a typical olfactory brain-response. We conclude in recommending this approach for minimized discomfort in fMRI of olfaction.