Severe Acute Hypoxemic Respiratory Failure Research Articles

The role of extracorporeal membrane oxygenation in congenital diaphragmatic hernia

The aim of this paper is to review the role of extracorporeal membrane oxygenation (ECMO) in neonates with severe acute hypoxemic respiratory failure secondary to congenital diaphragmatic hernia (CDH). The difficulties in identifying patients with fatal lung hypoplasia are highlighted and the role of adjunctive therapies on ECMO (surfactant, inhaled nitric oxide, high-frequency ventilation and liquid lung distension) as well as the timing of surgical repair is discussed. Survivors of severe CDH who have been supported on ECMO have significant late mortality and morbidity. There remains a need for a randomized controlled trial of the role of ECMO in neonates with severe CDH.

Outcome of mechanical ventilation for acute respiratory failure in patients with pulmonary fibrosis.

During the course of idiopathic pulmonary fibrosis patients may need invasive mechanical ventilation because of acute respiratory failure. We reviewed the charts of all patients with idiopathic pulmonary fibrosis admitted to our ICU for mechanical ventilation to describe their ICU course and prognosis. Retrospective, observational case series, from December 1996 to March 2001, in an 18-bed medical ICU in a tertiary university hospital. Fourteen consecutive patients with idiopathic ( n=11) or secondary ( n=3) pulmonary fibrosis admitted to the medical ICU for mechanical ventilation. Relevant factors of history and hospital course such as diagnostic and therapeutic interventions were retrieved as well as laboratory and radiological results. All patients were admitted for severe acute hypoxemic respiratory failure (PaO(2)/FIO(2) 111+/-64 mmHg), with a high clinical suspicion of lower respiratory tract infection. Despite ventilatory support and adjunctive therapies (antibiotics, steroids, or immunosuppressive drugs), all patients gradually worsened and eventually died in the ICU after a mean stay of 7.6+/-4.6 days. In this study mechanical ventilation for acute respiratory failure in pulmonary fibrosis patients was associated with a 100% mortality, despite aggressive therapeutic and diagnostic procedures.

Extracorporeal life support outcome for 128 pediatric patients with respiratory failure

Purpose: The aim of this study was to describe a single-center experience with pediatric extracorporeal life support (ECLS) and to determine variables predictive of outcome in pediatric patients, both before the institution of ECLS and while on support.Methods: From October 1985 to September 1998 the authors supported 128 children with severe acute hypoxemic respiratory failure (n = 121, Pao2/FIO2 ratio = 58 = ± 29) or acute hypercarbic respiratory failure (n = 7, PaCO2 = 128 ± 37), despite maximal conventional ventilation. Mode of access included venoarterial bypass (VA, n = 64), venovenous bypass (VV, n = 53), and VV to VA bypass (n = 11). The techniques used included lung rest, pulmonary physiotherapy, diuresis to dry weight using hemofiltration if needed, minimal anticoagulation, and optimal systemic oxygen delivery.Results: The median age was 1.4 years (range, 2 weeks to 17 years). The mean duration of ECLS was 288 ± 240 hours (range, 4 to 1148 hours or 0.2 to 47.8 days). Lung compliance increased from 0.32 ± 0.02 mL/cm H2O/kg to 0.59 ± 0.03 mL/cm H2O/kg in survivors, but only increased from 0.34 ± 0.02 mL/cm H2O/kg to 0.35 ± 0.02 mL/cm H2O/kg in nonsurvivors (P < .002 comparing change between survivors and nonsurvivors). Mean body weight decreased from 9% ± 2% over dry weight to 4% ± 2% in survivors, whereas in nonsurvivors the mean body weight increased from 25% ± 5% over dry weight to 35% ± 7% (P < .001). Outcome results by diagnosis were pneumonia, 73%; acute respiratory distress syndrome, 67%; and airway support, 60%, with overall lung recovery occurring in 77%, and hospital survival in 71%. Multivariate logistic regression modelling of patients with hypoxemic respiratory failure found the only pre-ECLS variable significantly associated with outcome to be pH (P < .05). Variables during the course of ECLS significantly associated with decreased survival were the presence of creatinine greater than 3.0 (P < .01), the need for inotropes (P < .04), failure to return the patient to dry weight (P < .04), and lung compliance that did not improve significantly. (P < .01).Conclusions: ECLS provides life support in severe respiratory failure in children, allowing time for injured lungs to recover. Pre-ECLS predictors, such as pH and variables during ECLS, such as presence of renal failure, improvement in compliance, return to dry weight, and the need for inotropes on ECLS, may be useful for predicting outcome.

Multicenter randomized controlled trial of the effects of inhaled nitric oxide therapy on gas exchange in children with acute hypoxemic respiratory failure

Objectives and background: To determine whether inhaled nitric oxide (iNO) therapy can attenuate the progression of lung disease in acute hypoxemic respiratory failure, we performed a multicenter, randomized, masked, controlled study of the effects of prolonged iNO therapy on oxygenation. We hypothesized that iNO therapy would improve oxygenation in an acute manner, slow the rate of decline in gas exchange, and decrease the number of patients who meet pre-established oxygenation failure criteria. Study design: A total of 108 children (median age 2.5 years) with severe acute hypoxemic respiratory failure from 7 centers were enrolled. After consent was obtained, patients were randomized to treatment with iNO (10 ppm) or mechanical ventilation alone for at least 72 hours. Patients with an oxygenation index ≥40 for 3 hours or ≥25 for 6 hours were considered treatment failures and exited the study. Results: Patient age, primary diagnosis, pediatric risk of mortality score, mode of ventilation, and median oxygenation index (35 ± 22 vs 30 ± 15; iNO vs control; mean ± SEM) were not different between groups at study entry. Comparisons of oxygenation indexes during the first 12 hours demonstrated an acute improvement in oxygenation in the iNO group at 4 hours (-10.2 vs -2.7, mean values; P < .014) and at 12 hours (-9.2 vs -2.8; P < .007). At 12 hours 36% of the control group met failure criteria in contrast with 16% in the iNO group ( P < .05). During prolonged therapy the failure rate was reduced in the iNO group in patients whose entry oxygenation index was ≥25 ( P < .04) and in immunocompromised patients ( P < .03). Conclusions: We conclude that iNO causes an acute improvement in oxygenation in children with severe AHRF. Two subgroups (immunocompromised and an entry oxygen index ≥25) appear to have a more sustained improvement in oxygenation, and we speculate that these subgroups may benefit from prolonged therapy. (J Pediatr 1999;134:406-12)

Timing of recovery of lung function after severe hypoxemic respiratory failure in children.

To describe the timing of recovery of lung function after severe acute hypoxemic respiratory failure (AHRF) in children. A serial observational follow-up study of clinical and lung function measurements up to 53 months after acute illness. University pediatric intensive care unit in a national children's hospital. Five critically ill children aged 5-14 years. None Clinical recovery: each patient required a 3-5 month convalescence before being able to attend full-time school because of lethargy and dyspnea. All patients developed wheeze 3-12 months after illness and four received long-term bronchodilator therapy. Lung function recovery: for both the forced vital capacity (FVC) and forced vital capacity in the first second (FEV1) four patients had abnormally low values, regaining only 60-70% of predicted values for their height and sex, and all of this improvement had occurred by 6-12 months after illness. Beyond this interval, patients remained on their same FVC and FEV1 centile. FEV1/FVC ratios were consistently within the normal range, indicating a predominantly restrictive defect. Changes in peak expiratory flow exhibited a time course of improvement similar to the other lung function tests. In children, pulmonary recovery after severe AHRF may occur for 6-12 months. A 1-year follow-up could offer a rational single point for assessment of outcome and long-term counselling of child and parents.

Extracorporeal life support for 100 adult patients with severe respiratory failure.

The authors retrospectively reviewed their experience with extracorporeal life support (ECLS) in 100 adult patients with severe respiratory failure (ARF) to define techniques, characterize its efficacy and utilization, and determine predictors of outcome. Extracorporeal life support maintains gas exchange during ARF, providing diseased lungs an optimal environment in which to heal. Extracorporeal life support has been successful in the treatment of respiratory failure in infants and children. In 1990, the authors instituted a standardized protocol for treatment of severe ARF in adults, which included ECLS when less invasive methods failed. From January 1990 to July 1996, the authors used ECLS for 100 adults with severe acute hypoxemic respiratory failure (n = 94): paO2/FiO2 ratio of 55.7+/-15.9, transpulmonary shunt (Qs/Qt) of 52+/-22%, or acute hypercarbic respiratory failure (n = 6): paCO2 84.0+/-31.5 mmHg, despite and after maximal conventional ventilation. The technique included venovenous percutaneous access, lung "rest," transport on ECLS, minimal anticoagulation, hemofiltration, and optimal systemic oxygen delivery. Overall hospital survival was 54%. The duration of ECLS was 271.9+/-248.6 hours. Primary diagnoses included pneumonia (49 cases, 53% survived), adult respiratory distress syndrome (45 cases, 51 % survived), and airway support (6 cases, 83% survived). Multivariate logistic regression modeling identified the following pre-ECLS variables significant independent predictors of outcome: 1) pre-ECLS days of mechanical ventilation (p = 0.0003), 2) pre-ECLS paO2/FiO2 ratio (p = 0.002), and 3) age (years) (p = 0.005). Modeling of variables during ECLS showed that no mechanical complications were independent predictors of outcome, and the only patient-related complications associated with outcome were the presence of renal failure (p < 0.0001) and significant surgical site bleeding (p = 0.0005). Extracorporeal life support provides life support for ARF in adults, allowing time for injured lungs to recover. In 100 patients selected for high mortality risk despite and after optimal conventional treatment, 54% survived. Extracorporeal life support is extraordinary but reasonable treatment in severe adult respiratory failure. Predictors of survival exist that may be useful for patient prognostication and design of future prospective studies.

Early Response to Inhaled Nitric Oxide and Its Relationship to Outcome in Children With Severe Hypoxemic Respiratory Failure

To examine whether the early response to inhaled nitric oxide (iNO) is a measure of reversibility of lung injury and patient outcome in children with acute hypoxemic respiratory failure (AHRF). Retrospective review study. Pediatric ICUs. Thirty infants and children, aged 1 month to 13 years (median, 7 months) with severe AHRF (mean alveolar arterial oxygen gradient of 568+/-9.3 mm Hg, PaO2/fraction of inspired oxygen of 56+/-2.3, oxygenation index [OI] of 41+/-3.8, and acute lung injury score of 2.8+/-0.1). Eighteen patients had ARDS. The magnitude of the early response to iNO was quantified as the percentage change in OI occurring within 60 min of initiating 20 ppm iNO therapy. This response was compared to patient outcome data. There was a significant association between early response to iNO and patient outcome (Kendall tau B r=0.43, p < 0.02). All six patients who showed < 15% improvement in OI died; 4 of the 11 patients (36%) who had a 15 to 30% improvement in OI survived, while 8 of 13 (61%) who had a > 30% improvement in OI survived. Overall, 12 patients (40%) survived, 9 with ongoing conventional treatment including iNO, and 3 with extracorporeal support. In AHRF in children, greater early response to iNO appears to be associated with improved outcome. This may reflect reversibility of pulmonary pathophysiologic condition and serve as a bedside marker of disease stage.

Dose-response to inhaled nitric oxide in acute hypoxemic respiratory failure of newborn infants: a preliminary report.

In acute hypoxemic respiratory failure of term and near-term neonates, extra- and intrapulmonary right-to-left shunting contribute to refractory hypoxemia. Inhaled nitric oxide (NO) decreases pulmonary arterial pressure and improves ventilation-perfusion mismatch in a variety of animal models and selected human patients. We report on 10 consecutive term and near-term newborns with severe acute hypoxemic respiratory failure due to diaphragmatic hernia, meconium aspiration syndrome, group B streptococcus sepsis, pneumonia or acute respiratory distress syndrome, who received increasing doses of inhaled NO (up to 80 ppm) to improve the arterial partial pressure of oxygen (PaO2). The response to NO and the optimum NO concentration which improved PaO2 varied considerably between patients. Improvement of PaO2 was absent or poor (less than 10 mm Hg) in the 4 newborns with meconium aspiration syndrome and in 1 patient with congenital diaphragmatic hernia, while in the other 5 patients inhaled NO increased the mean (+/- SE) PaO2 from 41 +/- 6 to 57 +/- 9 mm Hg (P < 0.05). Optimum NO concentrations determined by dose-response measurements performed during the first 8 hr of NO inhalation were 8-16 ppm except for 2 newborns with congenital diaphragmatic hernia who required 32 ppm to effectively increase PaO2. Four of the 5 patients in whom the PaO2 rose by more than 10 mm Hg received inhaled NO for extended periods of time (5 to 23 days) with no signs of tachyphylaxis. The optimum NO concentration dropped to less than 3 ppm after prolonged mechanical ventilation or when intravenous prostacyclin was given concomitantly.(ABSTRACT TRUNCATED AT 250 WORDS)