All tracheotomies were performed electively using the routine methods employed in children by most authorities. The immediate aftercare, including daily stoma care, suctioning, and change of tracheotomy tube, was done under strict protocols of hygiene and sterility.
Antibiotic Policy During the Study
No prophylaxis was implemented at any stage during both episodes of artificial ventilation. Systemic antibiotics were given only in case of infection. Infection was diagnosed on clinical signs of infection, including temperature of 38.5°C, leukocytosis > 12,000X109/L, elevated C-reactive protein (CRP) >15 μg/mL, combined with tracheal aspirates yielding >106 CFU/mL. All five requirements had to be fulfilled for the diagnosis of infection. Tracheobronchitis was distinguished from pneumonia by the absence of chest radiographic changes. Infection due to Gram-positive bacteria was, in general, treated with a first-generation cephalosporin, while a third-generation cephalosporin was administered in children who developed a lower airway infection caused by Gram-negative bacilli. Infection, in general, was treated with a 5-day course of antibiotics, followed by clinical reevaluation of the patient.
Definitions
1. Carriage or the carrier state existed when the same bacterial strain was isolated from at least two consecutive throat samples, in any concentration over a period of at least 1 week.
2. Colonization of the lower airways was defined as the presence of a microorganism in the lower airways. The diagnostic sample yielded <106, CFU/mL of diagnostic sample. The concentration of leukocytes in the lower airway secretions was, in general, few ( + ) or moderate ( + + ), on a semiquantitative scale of +, + + , + + + (many).
3. Infection of the lower airways was defined as a microbiologically proved diagnosis of local and/or systemic inflammation.
The diagnostic sample obtained from the lower airways yielded >106 CFU/mL of sample, and there were many leukocytes in the lower airway secretions.
(a) Tracheobronchitis was defined as follows: purulent endotracheal aspirate (WBC + + + ), and temperature >38.5°C, and leukocytosis (WBC >12,000X109/L) or leukopenia (WBC <4,000X109/L), and >106 CFU/mL of tracheal aspirate, and elevated CRP >15 μg/mL.
(b) Bronchopneumonia was the same five criteria as above, combined with the presence of a new or progressive pulmonary infiltrate on chest radiograph for >48 h.
4. Primary endogenous colonization or infection was defined as colonization or infection of the lower airways caused by a PPM isolated from the lower airway secretions, and carried by the patient in the throat at the time of admission to the PICU and/or tracheotomy.
5. Secondary endogenous colonization or infection was defined as colonization or infection of the lower airways caused by a PPM isolated from the tracheal aspirate, and not carried in the throat at the time of admission to the PICU and/or tracheotomy, but appearing later.
6. Exogenous colonization or infection was defined as colonization or infection of the lower airways caused by a PPM isolated from the tracheal aspirate and that was not previously carried by the child in the throat at any time.