Rationale: Spontaneous breathing during mechanical ventilation increases transpulmonary pressure and Vt, and worsens lung injury. Intuitively, controlling Vt and transpulmonary pressure might limit injury caused by added spontaneous effort. Objectives: To test the hypothesis that, during spontaneous effort in injured lungs, limitation of Vt and transpulmonary pressure by volume-controlled ventilation results in less injurious patterns of inflation. Methods: Dynamic computed tomography was used to determine patterns of regional inflation in rabbits with injured lungs during volume-controlled or pressure-controlled ventilation. Transpulmonary pressure was estimated by using esophageal balloon manometry [Pl(es)] with and without spontaneous effort. Local dependent lung stress was estimated as the swing (inspiratory change) in transpulmonary pressure measured by intrapleural manometry in dependent lung and was compared with the swing in Pl(es). Electrical impedance tomography was performed to evaluate the inflation pattern in a larger animal (pig) and in a patient with acute respiratory distress syndrome. Measurements and Main Results: Spontaneous breathing in injured lungs increased Pl(es) during pressure-controlled (but not volume-controlled) ventilation, but the pattern of dependent lung inflation was the same in both modes. In volume-controlled ventilation, spontaneous effort caused greater inflation and tidal recruitment of dorsal regions (greater than twofold) compared with during muscle paralysis, despite the same Vt and Pl(es). This was caused by higher local dependent lung stress (measured by intrapleural manometry). In injured lungs, esophageal manometry underestimated local dependent pleural pressure changes during spontaneous effort. Conclusions: Limitation of Vt and Pl(es) by volume-controlled ventilation could not eliminate harm caused by spontaneous breathing unless the level of spontaneous effort was lowered and local dependent lung stress was reduced.

The role of preserving spontaneous effort during mechanical ventilation and its interaction with mechanical ventilation have been actively investigated for several decades. Inspiratory muscle activities can lower the pleural components surrounding the lung, leading to an increase in transpulmonary pressure when spontaneous breathing effort is preserved during mechanical ventilation. Thus, increased transpulmonary pressure provides various benefits for gas exchange, ventilation pattern, and lung aeration. However, it is important to note that these beneficial effects of preserved spontaneous effort have been demonstrated only when spontaneous effort is modest and lung injury is less severe. Recent studies have revealed the ‘dark side’ of spontaneous effort during mechanical ventilation, especially in severe lung injury. The ‘dark side’ refers to uncontrollable transpulmonary pressure due to combined high inspiratory pressure with excessive spontaneous effort and the injurious lung inflation pattern of Pendelluft (i.e., the translocation of air from nondependent lung regions to dependent lung regions). Thus, during the early stages of severe ARDS, the strict control of transpulmonary pressure and prevention of Pendelluft should be achieved with the short-term use of muscle paralysis. When there is preserved spontaneous effort in ARDS, spontaneous effort should be maintained at a modest level, as the transpulmonary pressure and the effect size of Pendelluft depend on the intensity of the spontaneous effort.

An association between respiratory muscle weakness and sarcopenia may provide a clue to the mechanism of sarcopenia development. We aimed to clarify this relationship among community-dwelling older adults. In total, 117 community-dwelling older adults were assessed and classified into 4 groups: robust, respiratory muscle weakness, sarcopenia, and respiratory sarcopenia. The respiratory sarcopenia group (12%) had a significantly higher percentage of males and had lower BMI, skeletal muscle index, skeletal muscle mass, phase angle, and oral function than the robust group (32.5%). All physical functions were significantly lower. The respiratory muscle weakness group (54.7%) had a significantly lower BMI and slower walking speed, compared with the robust group. The sarcopenia group (0.8%) was excluded from the analysis. The percent maximum inspiratory pressure was significantly lower in both the respiratory muscle weakness and respiratory sarcopenia groups, compared with the robust group. Almost all participants with sarcopenia showed respiratory muscle weakness. In addition, approximately 50% had respiratory muscle weakness, even in the absence of systemic sarcopenia, suggesting that respiratory muscle weakness may be the precursor of sarcopenia. The values indicating physical function and skeletal muscle mass in the respiratory muscle weakness group were between those in the robust and the respiratory sarcopenia groups.

Background: Ultrasonography (US) is a feasible and accessible method for the measurement of skeletal muscle mass. This technique presents acceptable intra-rater reliability; however, there are a few reports on its inter-rater reliability. Additionally, relative reliability should equally be inspected to determine the presence of systematic errors. Therefore, this study aimed to investigate the intra- and inter-rater reliabilities and absolute reliability of rectus femoris muscle thickness as measured using US. Methods: The participants included in our study comprised 12 healthy young men (26.5 ± 3.9 years. Rectus femoris muscle thickness was measured from the right side of the thigh using US by two trained physical therapists. Inter- and intra-rater reliabilities were determined using the intraclass correlation coefficient (ICC) (1, 1) and ICC (2, 1) methods, respectively. Absolute reliability was evaluated using Bland − Altman analysis. Additionally, we calculated the minimal detectable change at the 95% level of confidence (MDC ₉₅ ). Result: According to the results of the Bland − Altman analysis, no fixed or proportional errors were present. The ICC (1, 1) was 0.95, and the ICC (2, 1) was 0.70. The MDC ₉₅ values of rectus femoris thickness for the intra- and inter-rater reliabilities were 2.0 mm and 4.3 mm, respectively. Conclusions: In our study, intra- and inter-rater reliabilities were measured at “excellent” and “moderate” levels in the healthy individuals based on a previously defined scale. Moreover, we determined the measurement error for quantifying rectus femoris thickness. Therefore, the measurement of rectus femoris thickness using US could be considered applicable in clinical research.

We investigated the effect of local injections of danazol suspension (DZS) into the uterine cervix. In the cervix, danazol (DZ) reached high concentrations 1 and 4–6 h after injection; then it decreased. In the endometrium, the DZ level reached a peak 1 h after injection, and then declined. On the other hand, the DZ concentration tended to increase with time after injection in ovarian tissue and it remained at a relatively constant level for more than 2 days. During treatment with DZS, various subjective symptoms and clinical findings gradually improved from the 4th week after the start of injection onward. Moreover, an improvement of subjective symptoms was observed in all the patients by the 24th week.