The effect of local anesthetic aerosol inhalation on the ventilatory response and the sensation of breathlessness to CO2 rebreathing was studied in seven healthy male subjects with permanent tracheal stomas after laryngectomy for carcinoma. Inhalation of bupivacaine aerosol sufficient to abolish the cough reflex to mechanical probing below the carina increased the ventilatory response to CO2 in six of seven subjects compared with saline control. This was achieved by an increase in both respiratory frequency (f) and tidal volume (VT) in four subjects, f in one subject, and VT in one subject. All subjects reported that they were more breathless on rebreathing after bupivacaine aerosol. The six subjects who recorded breathlessness with a visual analog scale (VAS) indicated its onset at a lower minute ventilation (VE) and gave higher VAS scores for equivalent levels of VE after threshold. We conclude that the enhanced CO2 sensitivity and breathlessness on rebreathing after airway anesthesia results from altered lower airway receptor discharge.

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.

Introduction Proximal row carpectomy (PRC) is a motion-sparing procedure for radiocarpal arthritis with reliable results. Traditionally, proximal capitate arthritis is a contraindication to PRC; however, PRC with modifications are proposed to circumvent this contraindication. PRC modifications can be broadly grouped into capitate resurfacing (CR) and capsular interposition (CI) procedures which could expand PRC indications. Our primary question was to characterize the outcomes achievable with various PRC modifications. Our secondary question was to determine which PRC modification was the optimal procedure when capitate arthritis was present. Methods A systematic review was conducted to examine the outcomes of modified PRC procedures. Independent reviewers appraised multiple databases for PRC studies with modifications for capitate arthritis in adult patients (age >18 years) with a minimum of three cases and extractable outcomes. Modified PRC procedures included capsular/allograft interposition, resurfacing capitate pyrocarbon implants, and osteochondral grafting. Pertinent outcomes included patient demographics, range-of-motion, grip strength, patient-reported outcomes, and complications, including salvage rates. Results Overall, 18 studies met the inclusion criteria—10 studies (n = 147) on CI and 8 studies on CR (n = 136). PRC with CI had the greatest flexion–extension arc and grip strength. Complications were marginally higher in the CR group (4%), while the CI group had a higher conversion to total wrist arthrodesis (10%). Conclusion Techniques to address capitate arthritis center around resurfacing or soft tissue interposition. PRC modifications with CI produces better range-of-motion and grip strength but higher conversion to total wrist arthrodesis. Higher conversion rates may be attributable to longer follow-up periods in studies examining CI compared with CR. Level of Evidence This is a Level III study.

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