A cortical contribution to breathing is determined by the presence of a Bereitschaftspotential, a low amplitude negativity in the averaged electroencephalographic (EEG) signal, which begins ∼1 s before inspiration. It occurs in healthy individuals when external inspiratory loads to breathing are applied. In chronic obstructive pulmonary disease (COPD), changes in the lung, chest wall and respiratory muscles produce an internal inspiratory load. We hypothesized that there would be a cortical contribution to quiet breathing in COPD and that a cortical contribution to breathing with an inspiratory load would be linked to dyspnoea, a major symptom of COPD. EEG activity was analysed in 14 participants with COPD (aged 57-84 years), 16 healthy age-matched (57-87 years) and 15 young (18-26 years) controls during quiet breathing and inspiratory loading. The presence of Bereitschaftspotentials, from ensemble averages of EEG epochs at Cz and FCz, were assessed by blinded assessors. Dyspnoea was rated using the Borg scale. The incidence of a cortical contribution to quiet breathing was significantly greater in participants with COPD (6/14) compared to the young (0/15) (P = 0.004) but not the age-matched controls (6/16) (P = 0.765). A cortical contribution to inspiratory loading was associated with higher Borg ratings (P = 0.007), with no effect of group (P = 0.242). The data show that increased age, rather than COPD, is associated with a cortical contribution to quiet breathing. A cortical contribution to inspiratory loading is associated with more severe dyspnoea. We propose that cortical mechanisms may be engaged to defend ventilation with dyspnoea as a consequence.

Key points Ageing is associated with changes in the respiratory system including in the lungs, rib cage and muscles. Neural drive to the diaphragm, the principal inspiratory muscle, has been reported to increase during quiet breathing with ageing. We demonstrated that low‐threshold motor units of the human diaphragm recruited during quiet breathing have similar discharge frequencies across age groups and shorter discharge times in older age. With ageing, motor unit action potential area increased. We propose that there are minimal functionally significant changes in the discharge properties of diaphragm motor units with ageing despite remodelling of the motor unit in the periphery. Abstract There are changes in the skeletal, pulmonary and respiratory neuromuscular systems with healthy ageing. During eupnoea, one study has shown relatively higher crural diaphragm electromyographic activity (EMG) in healthy older adults (>51 years) than in younger adults, but these measures may be affected by the normalisation process used. A more direct method to assess neural drive involves the measurement of discharge properties of motor units. Here, to assess age‐related changes in neural drive to the diaphragm during eupnoea, EMG was recorded from the costal diaphragm using a monopolar needle electrode in participants from three age groups (n ≥ 7 each): older (65–80 years); middle‐aged (43–55 years) and young (23–26 years). In each group, 154, 174 and 110 single motor units were discriminated, respectively. A mixed‐effects linear model showed no significant differences between age groups for onset (group mean range 9.5–10.2 Hz), peak (14.1–15.0 Hz) or offset (7.8–8.5 Hz) discharge frequencies during eupnoea. The motor unit recruitment was delayed in the older group (by ∼15% of inspiratory time; p = 0.02 cf. middle‐aged group) and had an earlier offset time (by ∼15% of inspiratory time; p = 0.04 cf. young group). However, the onset of multiunit activity was similar across groups, consistent with no global increase in neural drive to the diaphragm with ageing. The area of diaphragm motor unit potentials was ∼40% larger in the middle‐aged and older groups (P < 0.02), which indicates axonal sprouting and re‐innervation of muscle fibres associated with ageing, even in middle‐aged participants.

Surgical resection is recommended for all mucinous cystic neoplasms (MCNs) of the pancreas as a result of: 1) lack of an accurate tumor marker for invasive cancer; 2) young age at diagnosis; and 3) historical studies revealing 36 per cent incidence of malignancy in resected lesions. This study compares the clinicopathologic and prognostic features of our series of resected MCNs to recent studies using the current International Association of Pancreatology (IAP) system. Thirty-eight resected MCNs were identified. Almost all patients were female (97.4%); median age at diagnosis was 53.5 years (interquartile range [IQR], 41.3 to 61.0). The majority occurred in the body/tail of the pancreas (86.8%); median size on computed tomography/magnetic resonance imaging was 5.0 cm (IQR, 3 to 8.8). Comparison of the five high-grade (HG, 13.2%) and 33 low-grade (86.8%) MCNs revealed that 1) patients were similar in age (55.0 vs 52.0 years, respectively) and 2) HG lesions were significantly larger on preoperative imaging (9.9 vs 3.5 cm) and final pathology (10.9 vs 3.5 cm). These data, taken together with five recent studies that adhere to the 2012 IAP criteria (385 total MCNs), reveal that a cutoff of less than 3 cm without mural nodules would have only missed one (0.26%) HG lesion. Surveillance of these lesions may be appropriate for some patients.

Simultaneous electromyographic recordings from the human costal and crural diaphragm during voluntary augmented breathing and involuntary rebreathing show that the increase in inspiratory crural diaphragm activity was ~60% of the increase in costal diaphragm activity. However costal to crural diaphragm activation did not differ between the two tasks. The dissociation in the amplitude of activation of the costal and crural diaphragm becomes apparent only as the drive to breathe increases above tidal breathing.