Efficacy and safety of lung recruitment in pediatric patients with acute lung injury.

OBJECTIVE: To assess the safety and efficacy of a recruitment maneuver, the Open Lung Tool, in pediatric patients with acute lung injury and acute respiratory distress syndrome. DESIGN: Prospective cohort study using a repeated-measures design. SETTING: Pediatric intensive care unit at an urban tertiary children's hospital. PATIENTS: Twenty-one ventilated pediatric patients with acute lung injury. INTERVENTION: Recruitment maneuver using incremental positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS: The ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (Pao2/Fio2 ratio) increased 53% immediately after the recruitment maneuver. The median Pao2/Fio2 ratio increased from 111 (interquartile range, 73-266) prerecruitment maneuver to 170 (interquartile range, 102-341) immediately postrecruitment maneuver (p < .01). Improvement in Pao2/Fio2 ratio persisted with an increase of 80% over the baseline at 4 hrs and 40% at 12 hrs after the recruitment maneuver. The median Pao2/Fio2 ratio was 200 (interquartile range, 116-257) 4 hrs postrecruitment maneuver (p < .05) and 156 (interquartile range, 127-236) 12 hrs postrecruitment maneuver (p < .01). Compared with prerecruitment maneuver, the partial pressure of arterial carbon dioxide (Paco2) was significantly decreased at 4 hrs postrecruitment maneuver but not immediately after the recruitment maneuver. The median Paco2 was 49 torr (interquartile range, 44-60) prerecruitment maneuver compared with 48 torr (interquartile range, 43-50) immediately postrecruitment maneuver (p = .69), 45 torr (interquartile range, 41-50) at 4 hrs postrecruitment maneuver (p < .01), and 43 torr (interquartile range, 38-51) at 12 hrs postrecruitment maneuver. Recruitment maneuvers were well tolerated except for significant increase in Paco2 in three patients. There were no serious adverse events related to the recruitment maneuver. CONCLUSIONS: Using the modified open lung tool recruitment maneuver, pediatric patients with acute lung injury may safely achieve improved oxygenation and ventilation with these benefits potentially lasting up to 12 hrs postrecruitment maneuver.

Anemia, blood loss, and blood transfusions in North American children in the intensive care unit.

RATIONALE: Minimizing exposure of children to blood products is desirable. OBJECTIVES: We aimed to understand anemia development, blood loss, and red blood cell (RBC) transfusions in the pediatric intensive care unit (PICU). METHODS: Prospective, multicenter, 6-month observational study in 30 PICUs. Data were collected on consecutive children (<18 yr old) in the PICU for 48 hours or more. MEASUREMENTS AND MAIN RESULTS: Anemia development, blood loss, and RBC transfusions were measured. A total of 977 children were enrolled. Most (74%) children were anemic in the PICU (33% on admission, 41% developed anemia). Blood draws accounted for 73% of daily blood loss; median loss was 5.0 ml/day. Forty-nine percent of children received transfusions; 74% of first transfusions were on Days 1-2. After adjusting for age and illness severity, compared with nontransfused children, children who underwent transfusion had significantly longer days of mechanical ventilation (2.1 d, P < 0.001) and PICU stay (1.8 d, P = 0.03), and had increased mortality (odds ratio [OR], 11.6; 95% confidence interval [CI], 1.43-90.9; P = 0.02), nosocomial infections (OR, 1.9; 95% CI, 1.2-3.0; P = 0.004), and cardiorespiratory dysfunction (OR, 2.1; 95% CI, 1.5-3.0; P < 0.001). High blood loss per kilogram body weight from blood draws (OR, 1.11; 95% CI, 1.03-1.2; P = 0.01) was associated with RBC transfusion more than 48 hours after admission. The most common indication for transfusion was low hemoglobin (42%). Pretransfusion hemoglobin values varied greatly (mean, 9.7 +/- 2.7 g/dl). CONCLUSIONS: Critically ill children are at significant risk for developing anemia and receiving blood transfusions. Transfusion in the PICU was associated with worse outcomes. It is imperative to minimize blood loss from blood draws and to set clear transfusion thresholds.

Application of the acute respiratory distress syndrome network low-tidal volume strategy to pediatric acute lung injury.

In summary, most of the available data suggest that pediatric patients should be ventilated with low tidal volumes. The 6-mL/kg IBW tidal volume strategy as used in the ARDSNet studies is a reasonable target, having since been rigorously tested in several large, clinical trials (adult and pediatric). The mortality associated with ALI in these studies has never been lower, certainly supporting continued use of the 6 mL/kg target tidal volume as the "gold standard" and, thus, eliminating any equipoise in designing a pediatric trial comparing 6 mL/kg to a larger tidal volume. With mortality rates in children from ALI nearing 8% to 22% and with no clear surrogate outcomes identified to date, the sample sizes needed to show a significant clinical effect would be prohibitively large. Nonetheless, future research should compare 6 mL/kg IBW to even smaller tidal volumes or to high frequency ventilation in an attempt to further reduce the mortality associated with ALI and ARDS in the pediatric population.

Cumulative fluid intake minus output is not associated with ventilator weaning duration or extubation outcomes in children.

OBJECTIVE: The effect of fluid balance on respiratory outcomes for critically ill children has not been evaluated. The only indicator of fluid balance routinely recorded across our intensive care units was estimated fluid intake and output. We sought to determine whether cumulative intake minus output (I-O) at the start of weaning predicted weaning duration and whether cumulative I-O at extubation predicted extubation failure. DESIGN: Prospective observational study. SETTING: Ten pediatric intensive care units. PATIENTS: Cumulative I-O was recorded daily for 301 mechanically ventilated children (<18 yrs of age) from November 1999 through April 2001. INTERVENTIONS: Cumulative I-O was recorded during a study of weaning strategies and extubation failure in which mechanical ventilation of the majority of patients during weaning and extubation was managed according to a protocol that did not include fluid balance indicators. Outcomes were the time to successful removal of ventilatory support and the rate of initial extubation failure. MEASUREMENTS AND MAIN RESULTS: Relationships between cumulative I-O and outcomes were assessed by means of proportional hazards and logistic regression. The mean cumulative I-O per kilogram of ideal body weight at the start of weaning was 101 mL (sd, 180). Cumulative I-O at the time weaning was initiated did not predict duration of mechanical ventilator weaning. The mean cumulative I-O per kilogram of ideal body weight at extubation was 136 mL (sd, 237). Cumulative I-O at extubation did not predict extubation outcome. There was an association between cumulative I-O at extubation and the duration of weaning in cases not managed by a protocol. CONCLUSION: Although routinely recorded, cumulative fluid I-O does not appear to have clinical utility in cases managed according to a mechanical ventilator protocol in which tidal volume and oxygenation on minimal levels of ventilator support are systematically tested.

Lung aeration changes after lung recruitment in children with acute lung injury: a feasibility study.

RATIONALE: There are several adult studies using computed tomography (CT-scan) to examine lung aeration changes during or after a recruitment maneuver (RM) in ventilated patients with acute lung injury (ALI). However, there are no published data on the lung aeration changes during or after a RM in ventilated pediatric patients with ALI. OBJECTIVE: To describe CT-scan lung aeration changes and gas exchange after lung recruitment in pediatric ALI and assess the safety of transporting patients in the acute phase of ALI to the CT-scanner. METHODS: We present a case series completed in a subset of six patients enrolled in our previously published study of efficacy and safety of lung recruitment in pediatric patients with ALI. INTERVENTION: RM using incremental positive end-expiratory pressure. RESULTS: There was a variable increase in aerated and poorly aerated lung after the RM ranging from 3% to 72% (median 20%; interquartile range 6, 47; P = 0.03). All patients had improvement in the ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (PaO(2) /FiO(2)) after the RM (median 14%; interquartile range: 8, 72; P = 0.03). There was a decrease in the partial pressure of arterial carbon dioxide (PaCO(2)) in four of six subjects after the RM (median -5%; interquartile range: -9, 2; P = 0.5). One subject had transient hypercapnia (41% increase in PaCO(2)) during the RM and this correlated with the smallest increase (3%) in aerated and poorly aerated lung. All patients tolerated the RM without hemodynamic compromise, barotrauma, hypoxemia, or dysrhythmias. CONCLUSIONS: Lung recruitment results in improved lung aeration as detected by lung tomography. This is accompanied by improvements in oxygenation and ventilation. However, the clinical significance of these findings is uncertain. Transporting patients in early ALI to the CT-scanner seems safe and feasible.

Effect of mechanical ventilator weaning protocols on respiratory outcomes in infants and children: a randomized controlled trial.

CONTEXT: Ventilator management protocols shorten the time required to wean adult patients from mechanical ventilation. The efficacy of such weaning protocols among children has not been studied. OBJECTIVE: To evaluate whether weaning protocols are superior to standard care (no defined protocol) for infants and children with acute illnesses requiring mechanical ventilator support and whether a volume support weaning protocol using continuous automated adjustment of pressure support by the ventilator (ie, VSV) is superior to manual adjustment of pressure support by clinicians (ie, PSV). DESIGN AND SETTING: Randomized controlled trial conducted in the pediatric intensive care units of 10 children's hospitals across North America from November 1999 through April 2001. PATIENTS: One hundred eighty-two spontaneously breathing children (<18 years old) who had been receiving ventilator support for more than 24 hours and who failed a test for extubation readiness on minimal pressure support. INTERVENTIONS: Patients were randomized to a PSV protocol (n = 62), VSV protocol (n = 60), or no protocol (n = 60). MAIN OUTCOME MEASURES: Duration of weaning time (from randomization to successful extubation); extubation failure (any invasive or noninvasive ventilator support within 48 hours of extubation). RESULTS: Extubation failure rates were not significantly different for PSV (15%), VSV (24%), and no protocol (17%) (P =.44). Among weaning successes, median duration of weaning was not significantly different for PSV (1.6 days), VSV (1.8 days), and no protocol (2.0 days) (P =.75). Male children more frequently failed extubation (odds ratio, 7.86; 95% confidence interval, 2.36-26.2; P<.001). Increased sedative use in the first 24 hours of weaning predicted extubation failure (P =.04) and, among extubation successes, duration of weaning (P<.001). CONCLUSIONS: In contrast with adult patients, the majority of children are weaned from mechanical ventilator support in 2 days or less. Weaning protocols did not significantly shorten this brief duration of weaning.

The feasibility of conducting clinical trials in infants and children with acute respiratory failure.

Designing robust clinical trials in critically ill, mechanically ventilated children requires an understanding of the epidemiology and course of pediatric respiratory failure. As part of a clinical trial, we screened all mechanically ventilated children in nine large pediatric intensive care units (ICUs) across North America for 6 consecutive months. Of 6,403 total ICU admissions, 1,096 (17.1%) required mechanical ventilator support for a minimum of 24 hours. Of these, 701 (64%) met one or more exclusion criteria for trial enrollment. Common reasons for exclusion were upper airway obstruction (13.5%) and cyanotic congenital heart disease (11.5%). Life support interventions were restricted for 9.7% of patients, and 5.5% were chronically ventilator dependent. In the patients who were eligible for respiratory failure studies, 62.4% had an acute primary diagnosis of pulmonary disease, 14.2% neurologic disease, and 8.9% cardiac disease. Chronic underlying conditions were present in 43.2% of the patients. The most common acute diagnosis was bronchiolitis in infants (43.6%) and pneumonia in children 1 year old and older (24.5%). Mortality was rare (1.6%), and the median duration of ventilation was 7 days. The design of clinical trials in critically ill children is feasible but must account for the diverse population, infrequent mortality, and short duration of mechanical ventilation.