suggestions for short term study

hi there
could you please help me in searching a good research topic for a short term (intervention or observation of 3-5 days) study:
patient group: postvalvular surgery/ post CABG/ neonates( in ICU)
area of interest: role of chest binder, bronchial hygiene therapy, ventilators
facilities available: ultrasonography, ABG, radiographs other than routine monitoring in ICUs

please post some references as well if possible
thank you