Damping of the double giant dipole resonance

A microscopic approach is proposed to the damping of the double giant dipole resonance ͑DGDR͒. The double-time Green's function method is used to derive a closed set of coupled equations for the propagation of two-phonon excitation through the field of incoherent nucleon pairs. The analytical expressions for the width and energy shift of the DGDR are obtained. The numerical calculations are performed for 90 Zr, 90 Sn, and 208 Pb for several characteristics of the DGDR at zero as well as nonzero temperatures T. The results are found in reasonable agreement with existing experimental systematics for the width and energy of the DGDR. As compared to the estimation within the harmonic picture, the anharmonicity leads to a noticeable enhancement of the integrated photoabsorption cross section ͑IPACS͒ over the DGDR region. The DGDR width is found to increase sharply with increasing T at Tр3 MeV, but goes to a saturation at T Ͼ3 MeV. The harmonic limit for the DGDR width is restored already at Tу1.5 MeV. It is shown that the IPACS of the DGDR can also be enhanced compared to its harmonic value if it is built on a hot GDR

Successful lung-protective ventilatory management during the VV-ECMO in a severe COVID-19 pneumonia patient with extensive pneumomediastinum and subcutaneous emphysema: a case report

BACKGROUND: Ventilatory management of respiratory failure with pneumomediastinum/subcutaneous emphysema is not established. Herein, we report a case of severe COVID-19 pneumonia with extensive pneumomediastinum/subcutaneous emphysema, rescued by thorough lung-protective ventilatory management after applying the VV-ECMO. CASE PRESENTATION: A 68-year-old male with no medical history was admitted to a local hospital and diagnosed with COVID-19 pneumonia. His pulmonary parameters worsened during invasive ventilation due to the development of pneumomediastinum/subcutaneous emphysema, and then he was transferred to our hospital. On arrival, we immediately decided to apply VV-ECMO and switch to ultraprotective ventilation. After maintaining the initial ventilation with a neuromuscular blocking agent for 2 days, we gradually increased PEEP while limiting PIP to 25 cmH2O. The patient was weaned off VV-ECMO on day 10; he was transferred to the medical ward after extubation. CONCLUSIONS: Lung-protective ventilatory management should be performed thoroughly during VV-ECMO in severe COVID-19 pneumonia with pneumomediastinum/subcutaneous emphysema