The American review of respiratory disease
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In an attempt to assess the action of the sternocleidomastoid muscles on the human rib cage, we studied the pattern of rib cage motion in 2 patients with complete transection of the upper cervical cord. Measurements of rib cage motion were obtained with magnetometers and chest roentgenograms, and concentric needle electrodes were used to record the electromyograms (EMG) of various respiratory muscles. Spontaneous quiet breathing elicited a large amount of phasic inspiratory EMG activity not only in the sternocleidomastoids, but also in the trapezii, platysma, mylohyoid, and sternohyoid muscles. ⋯ During spontaneous inspiration both patients showed a clear-cut decrease in lower rib cage transverse diameter, and they both had a cranial displacement of the sternum and an increase in upper rib cage anteroposterior diameter that was disproportionately larger than the increase in lower rib cage anteroposterior diameter. Radiographic measurements confirmed these deformations but also demonstrated that the upper rib cage transverse diameter increased rather than decreased with inspiration. These results indicate that: (1) Patients with high tetraplegia use many neck muscles in addition to the sternocleidomastoids to breathe; (2) The synchronous contraction of these muscles acts to pull the sternum cranially, expands the upper rib cage, and causes paradoxical inward displacement of the lateral walls of the lower rib cage; (3) As in dogs, the motion of the upper rib cage in humans is more tightly linked to the sternum than that of the lower rib cage.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. Rev. Respir. Dis. · Jun 1986
Assessment of lung injury in the adult respiratory distress syndrome using multiple indicator dilution curves.
To assess its usefulness as an index of lung injury in critically ill patients with respiratory failure, the lung microvascular permeability surface area product for urea (14C-PSu) was measured using a multiple radioisotopic indicator dilution technique in 10 patients with the adult respiratory distress syndrome (ARDS) and in a control population of 5 patients without ARDS. The mean values for 14C-PSu and for extravascular lung water (EVLW) were both significantly elevated in patients with ARDS compared with those in control patients (14C-PSu: 18.7 +/- 4.4 versus 7.6 +/- 0.7, p less than 0.05; EVLW: 676 +/- 55 versus 269 +/- 53, p less than 0.001); 14C-PSu and EVLW were significantly correlated (R = 0.52, p less than 0.001). In the patients with ARDS, 14C-PSu and oxygenation, assessed as the alveolar-arterial oxygen difference, did not appear to be correlated. ⋯ These data suggest that measurement of 14C-PSu in critically ill patients is a clinically applicable parameter that reflects the degree of microvascular injury in groups of patients. However, our study did not indicate a clear advantage of 14C-PSu over EVLW in assessing lung injury in this patient population. The variability in 14C-PSu control patients also suggests that directional changes in 14C-PSu, as a measure of changes in the degree of lung microvascular dysfunction, should be interpreted with caution.