In intubated patients, respiratory variation of IVC diameter by 16% had fairly high diagnostic accuracy for predicting fluid responsiveness, but only when the tidal volume (TV) was ≥8 mL/kg and positive end-expiratory pressure (PEEP) ≤5 cm H2O.
Patients in PEA arrest with organized cardiac activity on bedside ultrasound appear to have better survival than those with disorganized, agonal cardiac activity and may respond to treatments not usually performed in standard ACLS, like continuous vasoactive drips during arrest.
Point of care ultrasound may be very useful during CPR, but it should not get in the way of chest compressions. If you're going to use it, get in there quick and get out of the way or choose a view that allows continuous chest compressions (i.e. subxiphoid).