Assessment of pulmonary function in the early phase of ARDS in pediatric patients.

Scant data are available on lung function in acute respiratory distress syndrome (ARDS) in pediatric patients. We measured respiratory mechanics by single-breath occlusion and maximum expiratory flow-volume curves by forced deflation in ten critically ill infants with clinical ARDS. Ten mechanically ventilated infants without lung disease served as the control group. To assess the severity of the lung injury in the infants with ARDS, we modified an adult scoring system that calculates a score (from 0 to 4; > 2.5 indicates severe lung injury) based on the extent of chest radiographic changes, degree of hypoxemia, amount of positive end-expiratory pressure (PEEP), and total respiratory system compliance. The lung injury scores of our patients were in the range of 2.75 to 3.75. The lung injury scores of the control group were zero. The predominant alteration in lung function was restrictive, as characterized by a significant decrease in total respiratory system compliance (0.41 +/- 0.13 ml/cmH2O/kg versus 1.12 +/- 0.16 ml/cmH2O/kg of controls; P < 0.001) and forced vital capacity (21.5 +/- 6.5 ml/kg versus 59.2 +/- 6.3 ml/kg of controls; P < 0.001). Maximum expiratory flow rates at 10% forced vital capacity were significantly increased (23.6 +/- 20.1 ml/kg/sec versus 8.4 +/- 2.5 ml/kg/sec of controls; P < 0.05), confirming the absence of any significant obstructive abnormalities. The passive expiratory flow-volume curves were curvilinear and convex in shape, indicating inhomogeneous lung pathology. The inhomogeneous distribution of lung injury in ARDS restricts the validity of respiratory mechanics measurements that rely on a single-compartment model. However, the forced deflation technique allows accurate spirometric assessments of the severity of restrictive (and obstructive) lung function changes in intubated infants with severe ARDS. Such measurements can be incorporated into lung injury scoring systems to classify the severity of the disease process for the purpose of outcome evaluation and to evaluate the effect of therapeutic interventions.

Cuffed endotracheal tubes in pediatric intensive care.

We prospectively studied 282 consecutive tracheal intubations (243 patients) in a pediatric intensive care unit during a 7-month period to compare cuffed and uncuffed endotracheal tube (ETT) utilization and outcome. The incidence of postextubation stridor in each ETT group was the major outcome measure after controlling for various patient risk factors. Patients whose ETTs were inserted in the operating room, who were less than 1 year of age, or who had ETTs in place for less than 72 hours were more likely to have had insertion of an uncuffed ETT. Patients whose ETTs were inserted in the emergency department or who were more than 5 years of age were more likely to have had insertion of a cuffed ETT. Those who had a cuffed ETT were older (mean 8.1 vs 2.5 years) and had ETTs in place longer (mean 6.1 vs 3.7 days) than patients with an uncuffed ETT. Of the 188 patients who subsequently had removal of their ETTs, the overall incidence of postextubation stridor was 14.9%, with no significant difference between the two ETT groups even after controlling for patient age, duration of intubation, trauma, leak around ETT before extubation, and pediatric risk of mortality score. Two patients in the cuffed ETT group and four patients in the uncuffed ETT group required reintubation for severe postextubation stridor. Long-term follow-up identified 33 patients (17%) who required hospital readmission. None of these was admitted with an upper airway problem. Two patients who previously had insertion of a cuffed ETT subsequently received tracheostomies for the primary purpose of long-term mechanical ventilation unrelated to any problem with the upper airway. We conclude that cuffed endotracheal intubation is not associated with an increased risk of postextubation stridor or significant long-term sequelae.

Intensive care course and outcome of patients infected with respiratory syncytial virus.

PICU admissions of 97 children positive for respiratory syncytial virus on fluorescent antibody screening were reviewed; 68% of 44 patients without history of preceding disease (Group I) and 79% of 53 patients with preceding pulmonary, cardiac, or other disease (Group II) required ventilation. In Group I ventilated children weighted significantly less (P = 0.001) and were of lower chronological (P = 0.02) and post-conceptional ages (P = 0.02) than those not ventilated. Eighteen infants ventilated for apnea weighted significantly less (P = 0.003), were more often born at less than or equal to 37 weeks gestation (P = 0.001) and were at lower post-conceptional age than 11 infants ventilated for progressive respiratory deterioration. There was no significant difference in mean weight, chronological age, post-conceptional age, CO2, or pH between 12 admissions with BPD who required ventilation for RSV infection and 5 who did not require ventilation. Ribavirin administration to five ventilated patients with BPD did not significantly alter the duration of intubation of PICU stay. Six patients with cardiac disease required longer periods of ventilation than others (Group I, P = 0.001; all others in Group II, P = 0.04). No deaths occurred in Group I, while 6 of 53 (11%) patients in Group II died. In this series immuno compromise placed patients at greatest risk of dying. Mechanical ventilation can be safely managed in previously healthy, RSV infected infants and should be initiated before significant cardiorespiratory compromise arises.

Varying tracheal cross-sectional area during respiration in infants and children with suspected upper airway obstruction by computed cinetomography scanning.

An ultrafast cinetomography computed tomographic scanner (cine-CT) was used to evaluate infants and children (n = 15) with suspected obstruction of the larynx or trachea. One scan sequence provided a single image at each of eight cross-sectional levels (volume-mode study). Each study, lasting 224 ms, covered the distance between the supraglottic area and the carina. Each patient also underwent a "dynamic" study at a specific level of interest determined from the volume-mode study. Forty images within 2.3 s covered at least one respiratory cycle. The images were displayed as a closed-loop movie and dynamic changes in laryngeal and tracheal caliber with respiration were monitored and quantitated. Tracheal boundaries were outlined either by a trackball-guided cursor (freehand) or semi-automated computer edge detection, and cross-sectional areas and diameters were determined. Reproducibility was tested among three investigators' freehand drawings and two automated computer drawings, at the same and at varying image intensities. The coefficient of variation for the computer-assisted records (0.2%) was smaller than for the best freehand drawing (1.5%). Tracheal diameters were reproducible, but with greater intra-individual investigator variability. Four normal tracheas had close to published measurements with conventional CT scanners. Cine-CT gives objective tracheal dimensions and their variation during respiration; it provides good anatomical detail above the carina, and also of the extra- and intra-thoracic vessels if injected with contrast medium.

Cell-mediated immunity in hepatic amoebiasis.

Cell-mediated immunity (CMI) was measured by blastic transformation of peripheral blood lymphocytes in 26 patients with amoebic liver abscess (ALA) and matched control subjects with no demonstrable clinical amoebiasis. During active disease, the mean mitogenic response, measured by the stimulation index of the patients' lymphocytes to Entamoeba histolytica antigen, was increased (mean +/- SD: 25.98 +/- 46.62 compared with 11.27 +/- 21.39), whereas that to phytohaemagglutinin (PHA) was reduced (54.80 +/- 56.26 compared with 111.70 +/- 70.61). Both these results were statistically significant (P less than 0.01); they do not, however, appear to be due to a quantitative defect in T-cell numbers, as both total peripheral lymphocytes (3332 +/- 1450 cells/microliters compared with 2447 +/- 531 cells/microliters) and T-cells (2652 +/- 1128 cells/microliters compared with 1908 +/- 386 cells/microliters) were significantly elevated in the patients (P less than 0.01). When these tests were repeated two months later in 12 cured patients they were found to be comparable to those of the control subjects. The results indicate that there is a transient cellular sensitization to amoebic antigen together with an increase in T-lymphocytes and an impairment of the mitogenic response of lymphocytes to PHA. The significance of these findings is discussed.

The phytohaemagglutinin response and lymphocyte subpopulations in young Blacks and Indians with insulin-dependent diabetes mellitus.

The lymphocyte transformation response to phytohaemagglutinin (PHA) and the relative numbers of T, B and null lymphocytes were studied in 32 insulin-dependent diabetics and 32 healthy matched controls. The mean stimulation index (Sl) of the 18 patients with poorly controlled diabetes mellitus was significantly lower than that of controls. No difference was seen in the mean Sl values of well-controlled diabetics compared with controls. Neither the well-controlled group nor the poorly controlled group showed any significant differences in the mean counts of the various lymphocyte subpopulations when compared with controls.