Evaluating the validity of responsiveness to inhaled nitric oxide in pediatric patients with ARDS: an analytic tool

Pediatric Acute Hypoxemic Respiratory Failure: Management of Oxygenation

Acute hypoxemic respiratory failure (AHRF) is one of the hallmarks of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are caused by an inflammatory process initiated by any of a number of potential systemic and/or pulmonary insults that result in heterogeneous disruption of the capillary-pithelial interface. In these critically sick patients, optimizing the management of oxygenation is crucial. Physicians managing pediatric patients with ALI or ARDS are faced with a complex array of options influencing oxygenation. Certain treatment strategies can influence clinical outcomes, such as a lung protective ventilation strategy that specifies a low tidal volume (6 mL/kg) and a plateau pressure limit (30 cm H2O). Other strategies such as different levels of positive end expiratory pressure, altered inspiration to expiration time ratios, recruitment maneuvers, prone positioning, and extraneous gases or drugs may also affect clinical outcomes. This article reviews state-of-the-art strategies on the management of oxygenation in acute hypoxemic respiratory failure in children.

Ventilation strategies and adjunctive therapy in severe lung disease

Respiratory failure caused by severe lung disease is a common reason for admission to the pediatric and neonatal intensive care units. Efforts to decrease morbidity and mortality have fueled investigations into innovative methods of ventilation, kinder gentler ventilation techniques, pharmacotherapeutic adjuncts, and extracorporeal life support modalities. This article discusses the rationale for and experience with some of these techniques.

Utilidad del óxido nítrico inhalado en paciente con síndrome de distrés respiratorio agudo y tetralogía de Fallot no intervenida

Utility of inhaled nitric oxide in the treatment of acute respiratory distress syndrome (ARDS) with pulmonary hypertension (PHT) is controversial and there are few studies in the literature that evaluate its effects during prolonged administration. We analyze the case of a 45 day old male patient with un-operated Fallot's tetralogy who developed ARDS and PHT with non-cardiac cause, that required prolonged mechanical ventilation (30 days) and administration of inhaled nitric oxide (INO). Before the INO, the oxygenation index was 19, and at a few minutes of its application it decreased to 15. The patient developed a dependence on INO, tolerating its gradual weaning. Administration could be interrupted at 27 days on onset. We did not observe toxic effects during the administration of INO.

Effects of Inhaled Nitric Oxide Administration on Early Postoperative Mortality in Patients Operated for Correction of Atrioventricular Canal Defects

OBJECTIVE

Postoperative pulmonary hypertension (POPH) substantially increases mortality after repair of congenital heart diseases. Inhaled nitric oxide (NO) has been reported as an effective and specific means of controlling POPH crisis. No randomized, placebo-controlled study has addressed the ability of NO administration to reduce mortality. Such a trial could raise ethical questions.

DESIGN

Observational study with historical control subjects based on multivariate confounder scores.

SETTING

Surgical pediatric ICU in a university hospital.

PATIENTS

Two hundred ninety-four records of patients operated on for atrioventricular (AV) canal between 1984 and 1994 who presented with severe POPH.

INTERVENTIONS

All variables found to be predictive for death by univariate tests were entered in a multivariate forward stepwise logistic regression model. Two paired groups regarding risk factors for death and only differing for POPH treatment (NO or conventional treatment) were constructed on the basis of predicted values obtained from this model. Twenty-five patients received NO, and 39 control patients, operated on between 1984 and 1994, received conventional treatment for POPH.

MEASUREMENTS AND RESULTS

Postoperative pulmonary pressure, date of operation, and occurrence of an infectious complication were retained in the model. The comparison between the two paired groups showed a significant difference in mortality (24%; 95% confidence interval [CI], 7 to 41%; vs 56%; 95% CI, 37 to 75%, respectively; p = 0.02).

CONCLUSIONS

This study suggests that there is a high probability for postoperative mortality reduction associated with administration of inhaled NO when severe POPH occurs in children operated for complete repair of AV canal.

Acute lung injury and acute respiratory distress syndrome

Acute lung injury and acute respiratory distress syndrome are an important challenge for pediatric intensive care units. These disorders are characterized by a significant inflammatory response to a local (pulmonary) or remote (systemic) insult resulting in injury to alveolar epithelial and endothelial barriers of the lung, acute inflammation and protein rich pulmonary edema. The reported rates in children vary from 8.5 to 16 cases / 1000 pediatric intensive care unit (PICU) admissions. The pathological features of ARDS are described as passing through three overlapping phases - an inflammatory or exudative phase (0-7 days), a proliferative phase (7-21 days) and lastly a fibrotic phase (from day 10). The treatment of ARDS rests on good supportive care and control of initiating cause. The goal of ventilating patients with ALI/ARDS should be to maintain adequate gas exchange with minimal ventilator induced lung injury. This can be achieved by use of optimum PEEP, low tidal volume and appropriate FiO2. High frequency ventilation can improve oxygenation but does affect the outcomes. Prone positioning is a useful strategy to improve oxygenation. Pharmacological strategies have not made any significant impact on the outcomes. Preliminary data suggests some role for use of corticosteroids in non-resolving ARDS. The mortality rates have declined over the last decade chiefly due to the advances in supporting critically ill patients.