RationaleDelivery of continuous positive airway pressure (CPAP) is the standard treatment for obstructive sleep apnoea in children and adults. Treatment adherence is a major challenge, as many patients find the CPAP mask uncomfortable. The study aim was to demonstrate the feasibility of delivered CPAP through customised nasal masks by assessing mask leak and comfort of customised masks compared to commercially available CPAP masks.MethodsSix healthy adult volunteers participated in a crossover study including commercial masks in three different sizes (petite, small/medium and large) from the same supplier and a customised mask fabricated for each subject using three-dimensional facial scanning and modern additive manufacturing processes. Mask leak and comfort were assessed with varying CPAP levels and mask tightness. Leak was measured in real time using an inline low-resistance Pitot tube flow sensor, and each mask was ranked for comfort by the subjects.ResultsMask leak rates varied directly with CPAP level and inversely with mask tightness. When ranked for comfort, three subjects favoured the customised mask, while three favoured a commercial mask. The petite mask yielded the highest mask leaks and was ranked least comfortable by all subjects. Relative mask leaks and comfort rankings for the other commercial and customised masks varied between individuals. Mask leak was comparable when comparing the customised masks with the highest ranked commercial masks.ConclusionCustomised masks successfully delivered target CPAP settings in all six subjects, demonstrating the feasibility of this approach.

The enteric nervous system (ENS) regulates the motor, secretory and defensive functions of the gastrointestinal tract. Enteric neurons integrate mechanical and chemical inputs from the gut lumen to generate complex motor outputs. How intact enteric neural circuits respond to changes in the gut lumen is not well understood. We recorded intracellular calcium in live‐cell confocal recordings in neurons from intact segments of mouse intestine in order to investigate neuronal response to luminal mechanical and chemical stimuli. Wnt1‐, ChAT‐ and Calb1‐GCaMP6 mice were used to record neurons from the jejunum and colon. We measured neuronal calcium response to KCl (75 mM), veratridine (10 μM), 1,1‐dimethyl‐4‐phenylpiperazinium (DMPP; 100 μM) or luminal nutrients (Ensure®), in the presence or absence of intraluminal distension. In the jejunum and colon, distension generated by the presence of luminal content (chyme and faecal pellets, respectively) renders the underlying enteric circuit unresponsive to depolarizing stimuli. In the distal colon, high levels of distension inhibit neuronal response to KCl, while intermediate levels of distension reorganize Ca2+ response in circumferentially propagating slow waves. Mechanosensitive channel inhibition suppresses distension‐induced Ca2+ elevations, and calcium‐activated potassium channel inhibition restores neuronal response to KCl, but not DMPP in the distended colon. In the jejunum, distension prevents a previously unknown tetrodotoxin‐resistant neuronal response to luminal nutrient stimulation. Our results demonstrate that intestinal distension regulates the excitability of ENS circuits via mechanosensitive channels. Physiological levels of distension locally silence or synchronize neurons, dynamically regulating the excitability of enteric neural circuits based on the content of the intestinal lumen. Key points How the enteric nervous system of the gastrointestinal tract responds to luminal distension remains to be fully elucidated. Here it is shown that intestinal distension modifies intracellular calcium levels in the underlying enteric neuronal network, locally and reversibly silencing neurons in the distended regions. In the distal colon, luminal distension is integrated by specific mechanosensitive channels and coordinates the dynamics of neuronal activation within the enteric network. In the jejunum, distension suppresses the neuronal calcium responses induced by luminal nutrients. Physiological levels of distension dynamically regulate the excitability of enteric neuronal circuits.

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