BACKGROUND: Administering anesthetics to the obese population requires caution because of a variety of reasons including possible interactions with the inflammatory process observed in obese patients. Propofol and dexmedetomidine have protective effects on pulmonary function and are widely used in short-and long-term sedation, particularly in intensive care unit settings in lean and obese subjects. However, the functional and biological effects of these drugs in obesity require further elucidation. In a model of diet-induced obesity, we compared the short-term effects of dexmedetomidine versus propofol on lung mechanics and histology, as well as biological markers of inflammation and oxidative stress modulation in obesity.

METHODS: Wistar rats (n= 56) were randomly fed a standard diet (lean) or experimental diet (obese) for 12 weeks. After this period, obese animals received sodium thiopental intraperitoneally and were randomly allocated into 4 subgroups:(1) nonventilated (n= 4) for molecular biology analysis only (control);(2) sodium thiopental (n= 8);(3) propofol (n= 8); and (4) dexmedetomidine (n= 8), which received continuous IV administration of the corresponding agents and were mechanically ventilated (tidal volume= 6 mL/kg body weight, fraction of inspired oxygen= 0.4, positive end-expiratory pressure= 3 cm H 2 O) for 1 hour.

RESULTS: Compared with lean animals, obese rats did not present increased body weight but had higher total body and trunk fat percentages, airway resistance, and interleukin-6 levels in the lung tissue (P= 0.02, P= 0.0027, and P= 0.01, respectively). In obese rats, propofol, but not dexmedetomidine, yielded increased airway resistance, bronchoconstriction index (P= 0.016, P= 0.02, respectively), tumor necrosis factor-α, and interleukin-6 levels, as well as lower levels of nuclear factor-erythroid 2–related factor-2 and glutathione peroxidase (P= 0.001, Bonferroni-corrected t test).

CONCLUSIONS: In this model of diet-induced obesity, a 1-hour propofol infusion yielded increased airway resistance, atelectasis, and lung inflammation, with depletion of antioxidative enzymes. However, unlike sodium thiopental and propofol, short-term infusion of dexmedetomidine had no impact on lung morphofunctional and biological variables.