Respiratory Care

Compare outcomes between physician-directed and protocol-directed weaning from mechanical ventilation in pediatric patients.

Prospective-randomized.

Pediatric and cardiac intensive care units in a 307-bed tertiary referral hospital for children.

The control group (physician-directed) was weaned according to individual physician order for reduc-tion in minute ventilation, positive end-expiratory pressure, and ordered oxygen saturation parameters for reduction in fraction of inspired oxygen (F10). The study group (protocol-directed) was weaned according to a predetermined algorithm developed for the purpose of this investigation.

The study enrolled 223 patients (116 physician-directed, 107 protocol-directed). All patients were mon-itored for hemodynamics, ventilator parameters, arterial blood gas values when available, oxygen saturation, weaning time, pre-weaning time, extubation time, and time on Fro, ≥ 0.40. We also moni-tored the incidence of reintubation, subglottic stenosis, tracheitis, and pneumonia. The protocol-directed group had additional measurements of actual versus predicted minute volume, comparisons of respi-ratory rate (actual versus predicted for age), and presence of spontaneous breathing effort for 10 consecutive minutes. Data analysis was done according to intent to treat.

There was no significant difference in 12-hour and 24-hour pediatric risk of mortality (PRISM III) scores between groups. The protocol-directed group overall had shorter total ventilation time, weaning time, pre-weaning time, time to extubation, and time on F10, > 0.40, although after stratification for respiratory diagnosis, only the difference in weaning time remained significant. There was no difference in the incidence of reintubation, new-onset tracheitis, subglottic stenosis, or pneumonia.

Protocol-directed weaning resulted in a shorter weaning time than physician-directed weaning in these pediatric patients.

Endotracheal suctioning of mechanically ventilated, very-low-birthweight infants for removal of respiratory secretions can be associated with morbidity. Routine endotracheal suctioning is inadvisable, but the safe minimum endotracheal suctioning frequency for prevention of airway obstruction has not been determined.

Decreasing suctioning frequency from every 4 hours to every 8 hours (plus as needed) would have no clinically important effect on the primary outcomes (nosocomial bloodstream infection [BSI], ventilator-associated pneumonia [VAP], and bacterial airway colonization) or secondary outcomes (reintubation rates, need for postural drainage, severity of bronchopulmonary dysplasia [BPD], neonatal mortality, duration of mechanical ventilation, and duration of hospitalization).

We conducted a sequential retrospective study of 90 very-low-birthweight infants who were mechanically ventilated for longer than 7 days and who underwent endotracheal suctioning every 4 hours (plus as needed) and 90 similar infants who underwent endotracheal suctioning every 8 hours (plus as needed). Two-pass endotracheal suctioning used during the study period required predetermined measurement of the suction catheter and prior instillation of saline.

The 2 treatment groups were similar in demographic and clinical characteristics, including survival (90% and 85%), age at time of death (28 and 33 d), mean birth-weight (926 and 934 g), gestational age (27 and 27 wk), duration of ventilation (29 and 27 d), and duration of stay (55 and 53 d). Regardless of suctioning frequency, airway colonization with Gram-positive cocci occurred in the majority of patients by 2 weeks of life. Forty-three percent of the infants suctioned every 4 hours and 44% of those suctioned every 8 hours became airway colonized with Gram-negative bacilli. No Gram-negative bacilli species was more likely to be associated with either treatment group. VAP was diag-nosed in 5 of the infants suctioned every 4 hours and in 9 of the infants suctioned every 8 hours. Nosocomial BSI occurred in 18 of the infants suctioned every 4 hours and in 21 of the infants suctioned every 8 hours. The difference in incidence of VAP and BSI was due to a Pseudomonas aeruginosa epidemic that started before the change in suctioning frequency. During hospitalization, approximately one fourth of the patients in each group required postural drainage and were reintubated 11 and 10 times per 100 ventilator days, respectively. A comparable number of infants in each group developed severe BPD and were discharged home on oxygen. Suctionings per patient per ventilator day were 6 for the group suctioned every 4 hours and 4 for the group suctioned every 8 hours (p < 0.01).

A low-frequency suctioning regimen (every 8 hours plus as needed) can be implemented without increasing the incidence of nosocomial BSI, VAP, bacterial airway colonization, frequency of reintubation, need for postural drainage, severity of BPD, neonatal mor-tality, duration of mechanical ventilation, or duration of hospitalization. Although the minimum suctioning frequency for removal of unwanted respiratory secretions is yet to be established, a substantial reduction in endotracheal suctioning frequency appears to be safe.

Mechanical ventilator failures expose patients to unacceptable risks and are expen- sive. By identifying factors that correlate with the amount of time between consecutive ventilator failures, we might reduce patient risk, save money, and shed light on a number of important questions concerning whether reliability changes as a function of time.

Investigate the correlation between several explanatory variables and the time between consecutive ventilator failures and address the following questions: (1) Are ventilators as safe and reliable following repairs as they were before failing? (2) Does reliability change significantly as a ventilator is used or ages? (3) Does a hospital's particular operating environment play a role in ventilator reliability? (4) Are ventilator service contracts worth the money?

A retrospective review was conducted using repair and maintenance records from 2 hospitals: a 570-bed teaching hospital and a 410-bed local community hospital. Records were examined from a total of 66 individual ventilators, of 5 different brands, used between July 1, 1991, and January 3, 2001. The ventilators included 13 Tyco-Mallinckrodt Infant Star, 10 Bird VIP, 11 Bird 6400ST, 16 Bird 8400STi, and 16 Tyco-Mallinckrodt 7200ae. The dependent variable was the operating time between or before unexpected mechanical failures; this was determined by the difference between hours logged on the ventilator hour meter at the time of failure and that recorded when the study began, or when the ventilator was new. Thereafter (when applicable), the time before failure was the difference in hours at consecutive failures. Seven independent explanatory covariates were selected and analyzed as potential correlates with time between failures. Another independent variable, the site of ventilator use (community or teaching hospital), was also tested for significance. Data were analyzed using the Cox proportional hazard model, the multiple-groups survival statistic, and the Cox-Mantel test.

In 2,567,365 hours of ventilator operation, 290 observations were recorded (226 failures and 64 censored observations). Two of the 7 covariates were judged time-dependent, excluded from the Cox model, and evaluated using other techniques. Of the 5 remaining covariates, 2 were significantly related to reliabil- ity, both indirectly. There was no difference in reliability, regardless of how many times a ventilator had been previously repaired, but hospital environment did significantly affect reliability.

Ventilator reliability depends on a number of factors. This study indicates that, on average, ventilator reliability improves the more a ventilator is used and the longer the brand has been commercially available. The number of previous ventilator repairs did not affect reliability, but the hospital environ- ment did. These data, if validated, should help to enhance our understanding of ventilator reliability and could eventually have profound economic and safety implications as well.