Journal of applied physiology
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Multiple breath nitrogen washout (MBNW) indices provide insight into ventilation heterogeneity globally [lung clearance index (LCI)] and within acinar (Sacin) and conducting (Scond) airways. Normal aging leads to an accelerated deterioration of Sacin in older adults, but little is known about the contribution of peripheral airway function to changes in pulmonary function indices reflecting expiratory airflow [forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)] and gas trapping [residual volume (RV)/total lung capacity (TLC)] with aging. We aimed to examine associations between MBNW and FEV1/FVC as well as RV/TLC in healthy adults, and to determine if these relationships differ in older (≥50 yr) versus younger subjects (<50 yr). ⋯ NEW & NOTEWORTHY This study explores associations between multiple breath nitrogen washout (MBNW) and standard pulmonary function indices reflecting expiratory airflow [forced expiratory volume in one second (FEV1)/forced vital capacity (FVC)] and gas trapping [residual volume (RV)/total lung capacity (TLC)] in healthy adults across a wide range of ages. We have demonstrated statistically significant relationships between MBNW and FEV1/FVC as well as RV/TLC. These findings provide novel evidence of the contribution of peripheral airway function to changes in standard pulmonary function indices with aging.
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Transcranial Doppler (TCD) ultrasonography is a noninvasive technique allowing continuous recording of cerebral blood flow (CBF) velocity. However, it is unclear whether the CBF estimated by TCD would be reliable for the comparison between individuals. The present study aimed to clarify the relationship between middle cerebral artery blood flow (MCA BF) measured by TCD and regional and total CBF measured by single-photon emission computed tomography (SPECT-CBF) with a quantification software program, a three-dimensional stereotaxic region of interest template. ⋯ These findings suggest that both mean MCA V and MCA BF with TCD ultrasonography would be useful for CBF comparison between individuals especially in the temporal region, although estimated blood flow with arterial area seems to be better than using simple flow velocity. NEW & NOTEWORTHY Correlations between middle cerebral artery blood flow (MCA BF) calculated by the product of MCA blood flow velocity (MCA V) and middle cerebral artery cross-sectional area and regional and total cerebral blood flow (CBF) measured by single-photon emission computed tomography (SPECT-CBF) were stronger as compared with those between MCA V and SPECT-CBF. These findings suggest that both mean MCA V and MCA BF would be useful for CBF comparison between individuals although estimated blood flow with arterial area seems to be better than using simple flow velocity.
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The validity and safety of using supramaximal verification (Smax) to confirm a maximal effort during cardiopulmonary exercise testing (CPET) in people with cystic fibrosis (CF) and/or those with severe disease has been questioned. Therefore, this study aimed to investigate these concerns in children, adolescents, and adults with mild-to-severe CF lung disease. Retrospective analysis of 17 pediatric and 28 adult participants with CF [age range: 9.2-62.9 y; forced expiratory volume in 1 s: 66.7% (range: 29.9%-102.3%); 30 men] who completed a routine ramp-incremental cycling test to determine peak oxygen uptake (V̇o2peak) was studied. ⋯ Given the clinical importance of aerobic fitness in people with CF, incorporating Smax is recommended to provide a safe and valid measure of V̇o2max in children, adolescents, and adults who span the spectrum of CF disease severity. NEW & NOTEWORTHY Incorporating supramaximal verification into cardiopulmonary exercise testing protocols did not increase the frequency of adverse events or perceived discomfort versus a single-phase incremental exercise test in people with mild-to-severe cystic fibrosis. Furthermore, a valid measure of maximal oxygen uptake (V̇o2max) was obtained from 85.7% of pediatric and 96.4% of adult exercise tests, whereas peak oxygen uptake underestimated aerobic fitness in comparison with V̇o2max in 21.4% of cases (by up to 24.4%).
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Neurogenic orthostatic hypotension (NOH) is a cardinal feature of autonomic dysfunction. The cortical autonomic network (CAN) is a network of brain regions associated with autonomic function. Therefore, our objective was to investigate whether impairment of CAN structures is involved in the pathophysiology of NOH. ⋯ Our result reveal that patients with autonomic dysfunction caused by postganglionic sympathetic impairment also have impaired activation of structures within the cortical autonomic network. Impaired activation is evident during a test of sympathetic, but not parasympathetic, activation. Impaired cortical autonomic networks associated with sympathetic activation may be involved in the pathophysiology of NOH.
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Evidence suggests that septic shock patients with chronic arterial hypertension may benefit from resuscitation targeted to achieve higher blood pressure values than other patients, possibly as a result of altered renal autoregulation. The effects of different vasopressor agents on renal autoregulation may be important in this context. We investigated the effects of arginine vasopressin (AVP) and norepinephrine (NE) on renal autoregulation in ovine septic shock. ⋯ After development of shock, the autoregulatory threshold was lower with AVP than with NE (59±5 vs. 65±7 mmHg, p=0.010). However, RBF was higher with NE both at the start of autoregulatory measurements (206±58 vs. 170±52 mL/min; p=0.050) and at the autoregulatory threshold (191±53 vs. 150±47 mL/min; p=0.008). As vasopressors may have different effects on renal autoregulation, blood pressure management in patients with septic shock should be individualized and take into account drug-specific effects.