Objectives Shear wave elastography is non-invasive ultrasound method and provides quantitative information on the elasticity of soft tissue. However, the universal velocity scale for quantification has not been developed. The aim of the study is to determine the shear wave velocities of abdominal muscle during anesthetic induction for future development on the universal scale. Methods We enrolled 75 adult patients undergoing elective surgery with ASA-PS I – III in the period between December 2018 and March 2021. We measured and calculated the shear wave velocity (SWV) before and after opioid administration (i.e., the baseline at rest and opioid-induced rigidity condition), and after muscle relaxant administration (i.e., zero reference condition). The SWV value was adjusted for the subcutaneous fat thickness by our proposed corrections. The SWVs after the adjustment were compared among the values in baseline, rigidity, and relaxation using one-way repeated-measures ANOVA and post hoc Tukey-Kramer test. A p-value of < 0.05 was considered to be statistically significant. UMIN Clinical Trials Registry identifier UMIN000034692, registered on October 30th, 2018. Results The SWVs in the baseline, opioid-induced rigidity, and muscle relaxation conditions after the adjustment were 2.08 ± 0.48, 2.41 ± 0.60, and 1.79 ± 0.30 m/s, respectively (p < 0.001 at all comparisons). Conclusion The present study suggested that the SWV as reference was 1.79 m/s and that the SWVs at rest and opioid-induced rigidity were ~ 10% and ~ 30% increase from the reference, respectively. The SWV adjusted for the subcutaneous fat thickness may be scale points for the assessment of muscle tone.

Postreperfusion syndrome presenting as posttransplant portal hypertension due to prolonged elevation of pulmonary vascular resistance and the role of nitroglycerin in diagnosis and treatment: a case report of Budd-Chiari syndrome.

Purpose Shear-wave elastography is a non-invasive ultrasound method that provides quantitative information on the elasticity of soft tissues. However, a universal velocity scale for quantification has yet to be developed. This study aimed to determine the shear-wave velocities (SWVs) of the abdominal muscles during anaesthesia induction for future development of a universal scale. Methods We enrolled 75 adult patients who received elective surgery with an American Society of Anesthesiologists physical status of I–III from December 2018 to March 2021. We measured and calculated the SWVs before and after opioid administration (baseline at rest and opioid-induced rigidity condition) and after muscle relaxant administration (zero reference condition). The SWV value was adjusted for subcutaneous fat thickness using our proposed corrections. The SWVs after the adjustment were compared among the values at baseline, opioid-induced rigidity, and complete muscle relaxation using one-way repeated-measures analysis of variance and post-hoc Tukey–Kramer tests. Significance was set at p < 0.05. Results The SWVs in the baseline, opioid-induced rigidity, and complete muscle relaxation conditions after adjustment were 2.08 ± 0.48, 2.41 ± 0.60, and 1.79 ± 0.30 m/s, respectively (p < 0.001 for all comparisons). Conclusion The SWV as reference was 1.8 m/s, and the SWVs at rest and opioid-induced rigidity were ~ 10% and ~ 30% higher than the reference, respectively. SWV adjusted for subcutaneous fat thickness may be a scale point for the assessment of muscle tone. Clinical trial registration: UMIN Clinical Trials Registry identifier UMIN000034692, registered on October 30th, 2018