Lung volume recruitment acutely increases respiratory system compliance in individuals with severe respiratory muscle weakness.

The aim of the present study was to determine whether lung volume recruitment (LVR) acutely increases respiratory system compliance (Crs) in individuals with severe respiratory muscle weakness (RMW). Individuals with RMW resulting from neuromuscular disease or quadriplegia (n=12) and healthy controls (n=12) underwent pulmonary function testing and the measurement of Crs at baseline, immediately after, 1 h after and 2 h after a single standardised session of LVR. The LVR session involved 10 consecutive supramaximal lung inflations with a manual resuscitation bag to the highest tolerable mouth pressure or a maximum of 50 cmH2O. Each LVR inflation was followed by brief breath-hold and a maximal expiration to residual volume. At baseline, individuals with RMW had lower Crs than controls (37±5 cmH2O versus 109±10 mL·cmH2O-1, p<0.001). Immediately after LVR, Crs increased by 39.5±9.8% to 50±7 mL·cmH2O-1 in individuals with RMW (p<0.05), while no significant change occurred in controls (p=0.23). At 1 h and 2 h post-treatment, there were no within-group differences in Crs compared to baseline (all p>0.05). LVR had no significant effect on measures of pulmonary function at any time point in either group (all p>0.05). During inflations, mean arterial pressure decreased significantly relative to baseline by 10.4±2.8 mmHg and 17.3±3.0 mmHg in individuals with RMW and controls, respectively (both p<0.05). LVR acutely increases Crs in individuals with RMW. However, the high airway pressures during inflations cause reductions in mean arterial pressure that should be considered when applying this technique.

Reduction in Bladder-Related Autonomic Dysreflexia after OnabotulinumtoxinA Treatment in Spinal Cord Injury.

Bladder-related events, including neurogenic detrusor overactivity, are the leading cause of autonomic dysreflexia in spinal cord injured individuals. Self-reported autonomic dysreflexia is reduced following onabotulinumtoxinA treatment for neurogenic detrusor overactivity; however, none of these trials have assessed autonomic dysreflexia events using the clinical cutoff of an increase in systolic blood pressure ≥20 mm Hg. This study used a prospective, open-labelled design from 2013 to 2014 to quantitatively assess the efficacy of one cycle 200 U intradetrusor-injected onabotulinumtoxinA (20 sites) on reducing the severity and frequency of bladder-related autonomic dysreflexia events and improving quality of life. Twelve men and five women with chronic, traumatic spinal cord injuries at or above the sixth thoracic level, and concomitant autonomic dysreflexia and neurogenic detrusor overactivity, underwent blood pressure monitoring during urodynamics and over a 24 h period using ambulatory blood pressure monitoring pre- and 1 month post-treatment. Post-onabotulinumtoxinA, autonomic dysreflexia severity was reduced during urodynamics (systolic blood pressure increase: 42 ± 23 mm Hg vs. 20 ± 10 mm Hg, p < 0.001) and during bladder-related events across the 24 h period (systolic blood pressure increase: 49 ± 2 mm Hg vs. 26 ± 22 mm Hg, p = 0.004). Frequency of 24 h bladder-related autonomic dysreflexia events was also decreased post-onabotulinumtoxinA (4 ± 2 events vs. 1 ± 1 events, p < 0.001). Autonomic dysreflexia and incontinence quality of life indices were also improved post-onabotulinumtoxinA (p < 0.05). Intradetrusor injections of onabotulinumtoxinA for the management of neurogenic detrusor overactivity in individuals with high level spinal cord injuries decreased the severity and frequency of bladder-related episodes of autonomic dysreflexia, and improved bladder function and quality of life.

Characterisation of baroreflex sensitivity of recreational ultra-endurance athletes.

Altered autonomic function has been identified following ultra-endurance event participation among elite world-class athletes. Despite dramatic increases in recreational athlete participation in these ultra-endurance events, the physiological effects on these athletes are less known. This investigation sought to characterise changes in surrogate measures of autonomic function: heart rate variability (HRV), blood pressure variability (BPV) and baroreceptor sensitivity (BRS) following ultra-endurance race participation. Further, we sought to compare baseline measures among ultra-endurance athletes and recreationally active controls not participating in the ultra-endurance race. Recreational ultra-endurance athletes (n = 25, 44.6 ± 8.2 years, 8 females) and recreationally active age, sex and body mass index matched controls (n = 25) were evaluated. Measurements of HRV, BPV and BRS were collected pre- and post-race for recreational ultra-endurance athletes and at baseline, for recreationally active controls. Post-race, ultra-endurance athletes demonstrated significantly greater sympathetic modulation [low frequency (LF) power HRV: 50.3 ± 21.6 normalised units (n.u.) to 65.9 ± 20.4 n.u., p = 0.01] and significantly lower parasympathetic modulation [high frequency (HF) power HRV: 45.0 ± 22.4 n.u. to 23.9 ± 13.1 n.u., p < 0.001] and BRS. Baseline measurements BRS (spectral: 13.96 ± 10.82 ms·mmHg(-1) vs. 11.39 ± 5.33 ms·mmHg(-1)) were similar among recreational ultra-endurance athletes and recreationally active controls, though recreational ultra-endurance athletes demonstrated greater parasympathetic modulation of some HRV and BPV measures. Recreational ultra-endurance athletes experienced increased sympathetic tone and declines in BRS post-race, similar to previously reported elite world-class ultra-endurance athletes, though still within normal population ranges.

A segmental evaluation of arterial stiffness before and after prolonged strenuous exercise.

We aimed to investigate the effects of a single session of prolonged strenuous exercise (PSE) on arterial stiffness by measuring pulse wave velocity (PWV) before and after competition in an ultramarathon. A total of 20 routine ultramarathon competitors (UM) completed baseline and postrace evaluation of central PWV (cPWV), upper-limb PWV (uPWV), and lower-limb PWV (lPWV) using carotid artery - femoral artery, carotid artery - finger, and femoral artery - toe segments, respectively. Fourteen additional age- and gender-matched normally active participants (NA) took part in the identical baseline evaluation but did not participate in the race. Average ultramarathon completion time was 30 h 47 min. Mean arterial blood pressure was reduced after exercise (before exercise (pre), 92 ± 7 mm Hg; after exercise (post), 84 ± 7 mm Hg; P < 0.001), whereas heart rate was increased (pre, 57 ± 10 beats·min(-1); post, 73 ± 12 beats·min(-1); P < 0.001). Also, lPWV (pre, 11.8 ± 3.6 m·s(-1); post, 9.6 ± 2.6 m·s(-1); P < 0.05) and uPWV (pre, 5.0 ± 0.53 m·s(-1); post, 4.4 ± 0.8 m·s(-1); P < 0.01) were reduced after exercise. No change in cPWV occurred (pre, 4.1 ± 0.8 m·s(-1); post, 3.9 ± 1.3 m·s(-1); P = 0.55). At baseline, the NA group had significantly increased cPWV in comparison with the UM group (UM, 4.1 ± 0.8 m·s(-1); NA, 7.4 ± 1.3 m·s(-1); P < 0.001). Acute participation in PSE influenced peripheral but not central arterial stiffness. Those who routinely participate in PSE have reduced central arterial stiffness as compared with normally active, age- and gender-matched controls.