[An experimental study on the safety of intratracheal drug administration].

Objective: To explore whether injury and repair occur in the trachea and the lung after intra-tracheal administration of different drugs.

Methods: Wistar rats were randomly divided into 5 groups, a normal group, a blank control (BC) group, a normal saline (NS) group, a lidocaine (LD) group and an amikacin (AK) group. For the latter 3 groups, normal saline, lidocaine and amikacin were injected into trachea by needle puncture. Scanning electron microscope was used to observe the ultra-structural changes of the epithelium, and the percentage of the area of damage (PAD) in tracheal mucosa was calculated. Moreover, pathological changes of the mucous membrane of bronchioles and alveolar epithelial cells were also examined, and the degree of lung pathology was semi-quantified.

Results: Two hours after the injection of the 3 drugs, derangement and edema of the cilia were evident by scanning electron microscopy. The PAD of the NS group, the LD group and the AK group were (94.2 ± 3.2)%, (93.1 ± 3.0)% and (95.5 ± 1.8)%, respectively; all being significantly higher than that of the BC group (1.3 ± 0.3)%. For the NS group and the LD group, the PAD decreased significantly after 24 h, which were (73.7 ± 7.8)% and (81.0 ± 4.6)% respectively, and returned to normal at 48 h and 96 h. While for the AK group, the damage began to improve at 72 h [PAD (62.1 ± 5.2)%], and recovered at 96 h. Airway epithelial derangement and cell edema in the alveoli and the bronchioles also occurred 2 h after drug injection, and inflammatory cell infiltration became evident at 24 h. At this time, the score of pathology was 1.80 ± 0.84, 2.60 ± 0.55 and 2.80 ± 0.45 for the NS group, the LD group and the AK group, respectively; all being higher than that of the BC group (0). These pathological changes recovered totally after 72 h for the NS and the LD groups, and 96 h for the AK group.

Conclusions: Intra-tracheal administration of normal saline, lidocaine and amikacin in rats led to reversible airway mucosal and lung tissue damages.