Although use of dexmedetomidine was associated with a greater duration of NIV vs placebo ( @ -LSB- @-@ -RSB- vs. @ -LSB- @-@ -RSB- h , P = @ ) , the total ventilation duration ( NIV + invasive ) was similar ( @ -LSB- @-@ -RSB- days vs. @ -LSB- @-@ -RSB- days , P = @ ) .