This is a retrospective study of patients with LTB who were intubated and ventilated in the ICU of our institution during the period January 1993 to December 1996. Over this 4-year period, 82 black children (58 males and 24 females) with a median age of 12.5 months (range 1-96 months) and median weight of 8.6 kg (range 3.7-25 kg) were treated. Of the 82 patients who were intubated, 85% were intubated in the operating room by a senior anaesthetist following a controlled gas induction. Patients with epiglottits, spasmodic croup and a previous history of upper airway problems were excluded from the present study.
The upper airway component (laryngotracheitis) of the disease (LTB) was based on the following clinical and chest radiographic criteria: barking cough, coryza, fever, inspiratory stridor and the `steeple sign' of the trachea in children who had a preintubation chest radiograph (which indicates upper airway narrowing). The following grading system for inspiratory stridor was used: grade 1, inspiratory stridor only; grade 2, as grade1 plus expiratory stridor; grade 3, as grade 2 plus pulsus paradoxus; and grade 4, as grade 3 plus cyanosis/mental obtundation . All patients admitted into the ICU had either grade 3 or grade 4 stridor. The lower airway (bronchitic) component of the disease (LTB) was based on any of the following criteria either alone or in combination on admission to the ICU: PaO2:FIO2 ratio; the need for positive-pressure mechanical ventilation; the presence of bronchopneumonia on chest radiography; atelectasis; and use of antibiotics.
Bronchopneumonia was defined as an infiltrate in any one or more of the four quadrants on the chest radiograph. Specimens from the trachea were not routinely examined or cultured to detect viral or bacterial isolates.
Steroids given were dexamethasone in 44 patients (0.4 mg/kg every 12 h for four doses), hydrocortisone in 17 patients (2.1 mg/kg, every 6 h for 28 doses on average) and prednisolone (1 mg/kg daily for an average of 5 days) in nine patients. The timing of steroids was either from admission, from just before extubation, or both at admission and before extubation. Extubation criteria were not documented, even though it is unit policy to wait for an air leak of about 15-20% of the tidal volume (Siemens 900C ventilator; Siemens, Solna, Stockholm, Sweden) in patients with upper airway swelling in particular, as well as to adhere to traditional weaning criteria in general .
Antibiotics were started at admission to the ICU either empirically (for bronchopneumonia) or during ICU stay for proven or suspected infection, on the basis of chest radiography, blood cultures and blood counts. Atelectasis was diagnosed on the chest radiograph on the basis of tracheal deviation, shift of the lung fissures and infiltrates. The number of days of intubation was counted from the time of initial intubation to the time of extubation. The PaO2:FIO2 ratio was used to document severity of shunt on admission (severity of lower airway disease). A grading system was used as follows: grade 4, PaO2:FIO2 <100; grade 3, PaO2:FIO2<200; grade 2, PaO2:FIO2<300; grade 1, PaO2:FIO2 >300.
Database management and statistical analysis were performed with SAS software, version 6.12 (SAS Institute Inc, Cary, NC, USA). The age, weight and intubation days (all non-normal distribution) as well as the PaO2:FIO2 ratios (ordinal data) are expressed as median (range). Univariate and multivariate logistic analysis were tested for reintubation with the following predictive variables: age, steroids, pneumonia, intubation days, PaO2:FIO2 ratio, atelectasis and antibiotics. The results were expressed as estimated coefficients, P value and odds ratio (95% confidence intervals) for each variable. P < 0.05 was considered statistically significant.