Table 2 Mechanisms by which sedation might promote ICU-acquired infection

Prolongation of exposure to risk factors

   Longer duration of mechanical ventilation, and ICU stay

[17, 23]

Prospective cohorts/5183, and 252; respectively

Durations of mechanical ventilation and ICU stay significantly longer in patients receiving sedation compared with those without sedation

Microaspiration

   Neurologic impairment

[23]

Prospective cohort/360

Heavy sedation significantly associated with microaspiration confirmed by pepsin-positive tracheal aspirate

   Impaired tubular esophageal motility

[34]

Prospective cohort/21

Esophageal motility significantly reduced in sedated patients compared to healthy controls

Microcirculatory disturbances

[35]

Prospective cohort/10

Sedation induced an increase in cutaneous blood flow, a decrease in reactive hyperemia, and alterations of vasomotions

Gastrointestinal motility disturbances

   Opioids

[40]

Double-blind, placebo-controlled, randomized study comparing the effects of lactulose, polyethylene glycol, or placebo on defecation/308

Morphine administration associated with a longer time before first defecation, except in the polyethylene glycol group

   Dexmedetomidine and clonidine

[47]

Animal study/NA

Clonidine and dexmedetomidine concentration-dependently increased peristaltic pressure threshold and inhibited peristalsis

Immunomodulatory effects

-

-

Please see Table 3 for details