The suprasternal notch as a landmark of chest compression depth in CPR.

OBJECTIVE: This study was performed to determine a landmark for chest compression depth for adult cardiopulmonary resuscitation (CPR) using chest computed tomography and to evaluate the validity of the landmark. METHODS: The external anteroposterior diameters (EAPDs) of each chest at the suprasternal notch (SN) and the lower half (LH) of the sternum were measured. We analyzed the differences in the EAPDs between the LH and the SN in each EAPD group in the LH of the sternum as follows: less than 20.00, 20.00 to 21.99, 22.00 to 23.99, greater than or equal to 24.00. We compared the differences in the EAPDs between the 2 points with 50 mm and the chest compression depth on simulated one-fourth external chest compressions for each EAPD group on the LH of the sternum. RESULTS: The mean difference in the EAPDs between the SN and the LH was 5.16 ± 0.91 mm. The differences in the EAPDs between the SN and the LH of the sternum with 50 mm did not indicate a significant difference. The mean one-fourth EAPD at the LH of the sternum was 5.50 ± 0.53 mm. There was not a significant difference in the residual chest depth on one-fourth simulated chest compression for each EAPD group on the LH of the sternum. CONCLUSIONS: The SN may have value as a functional landmark for chest compression depth in adult CPR. Our findings combined with the simulated one-fourth chest compressions were more consistent with the depth between 50 and 60 mm recommended by the 2015 CPR guidelines.

Cell-recycle continuous fermentation of Enterococcus faecalis RKY1 for economical production of lactic acid by reduction of yeast extract supplementation.

Both lactic acid productivity and cell growth were linearly correlated with yeast extract supplementation in batch fermentation. During conventional continuous operation, although fresh feed was introduced into the bioreactor with a significantly low dilution rate (0.04 h(-1)), the amount of yeast extract employed was not enough to maintain the growth of microorganism. However, when the fresh feed contained 100 g/l glucose and 2 g/l yeast extract during cell-recycle continuous operation at a dilution rate of 0.04 h(-1), more than 90 g/l lactic acid was continuously produced, with the average productivity of 3.72 g/l·h. In this experiment, 82 g of yeast extract (77% of reduction yield) could be reduced for the production of 1 kg of lactic acid compared with batch fermentation of a similar volumetric productivity.