#	Search history
#1	(TS="critical care") or (TS="life support") or (TS="intensive care") or (TS="coronary care") or (TS="cardiothoracic unit") or (TS=(ICU or ITU or CCU or CTU)) or (TS="critical* ill*")
#2	(TS="Respiration, Artificial") or (TS="Ventilators, Mechanical") or (TS="artificial* respirat*") or (TS="mechanical* ventilat*") or (TS="positive pressure ventilat*") or (TS="non invasive ventilat*")
#3	#1 or #2
#4	(TS="lateral position*") or (TS="lateral rotat*") or (TS="lateral recumben*") or (TS="lateral turn*" ) or (TS="lateral decubit*") or (TS="lateral tilt*") or (TS="side lying") or (TS="side position*") or (TS="lateral" and TS=Posture) or (TS="dependent position*")
#5	(TS="prone position*") or (TS="supine position*") or (TS="head down tilt") or (TS="dorsal position*") or (TS= recumben*) or (TS="horizontal position*") or (TS="ventral decubit*" ) or (TS="head tilt") or (TS=Trendelenburg) or (TS="vertical position*") or (TS="degree* position*") or (TS="backrest elevat*") or (TS="head elevat*") or (TS=Fowler*) or (TS="semi recumben*" or TS="semirecumben*") or (TS=sitting) or (TS="upright position*") or (TS=position* and TS=Posture)
#6	#4 or #5
#7	#3 and #6
#8	(TS="random* control* trial*") or (TS="clinical trial*") or (TS=((singl* or doubl* or trebl* or tripl*) SAME (blind* or mask*))) or (TS=placebo*) or (TS=random*) or (TS=(control* or prospectiv* or volunteer*))
#9	#7 and #8