High-frequency oscillatory ventilation for adult patients with ARDS.

High-frequency oscillatory ventilation (HFOV) is characterized by the rapid delivery of small tidal volumes (Vts) of gas and the application of high mean airway pressures (mPaws). These characteristics make HFOV conceptually attractive as an ideal lung-protective ventilatory mode for the management of ARDS, as the high mPaws prevent cyclical derecruitment of the lung and the small Vts limit alveolar overdistension. In this review, we will summarize the literature describing the use of HFOV in adult patients with ARDS. In addition, we will discuss recent experimental studies of HFOV that have advanced our understanding of its mechanical properties. We identified 2 randomized controlled trials (RCTs) and 12 case series evaluating HFOV in adults with ARDS. In these studies, HFOV appears to be safe and consistently improves oxygenation when used as a rescue mode of ventilation in patients with severe ARDS. The two RCTs comparing HFOV to conventional ventilation revealed encouraging results but failed to show a mortality benefit of HFOV over conventional ventilation. Further research is needed to identify optimal patient selection, technique, the actual Vt delivered, and the role of combining HFOV with other interventions, such as recruitment maneuvers, prone positioning, and nitric oxide.

Clinical characteristics and outcome of severe melioidosis requiring intensive care.

STUDY OBJECTIVE: To describe the clinical characteristics and outcome of patients with severe melioidosis requiring intensive care. DESIGN: Retrospective chart review. SETTING: Two ICUs from a tertiary-care teaching hospital. PATIENTS: Twenty-seven adult ICU patients with microbiologically documented melioidosis. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The median age was 59 years with a male preponderance (26:1). Twenty patients (74%) had medical comorbidities, with diabetes mellitus being the most common (59.3%). Almost all patients (96.3%) were bacteremic. Twenty patients (74.1%) presented with pneumonia. Twenty patients (74.1%) were in septic shock, and 16 patients (59.3%) had ARDS. Twelve patients (44.4%) required hemodialysis. The patients had a median of three organ dysfunctions, and the median APACHE (acute physiology and chronic health evaluation) II score was 27. The overall mortality was 48.1%. Mortality among patients with septic shock was 60%. The median ICU length of stay for survivors and nonsurvivors was 11 days and 2 days, respectively. Multivariate analysis revealed that the number of organ dysfunctions is an independent predictor of mortality (odds ratio, 8.2; 95% confidence interval, 1.3 to 51.4). CONCLUSIONS: The outcome of severe melioidosis requiring intensive care is poor, with death being predicted by the number of organ dysfunctions.

Pulmonary capillaritis in IgA nephropathy.

Pulmonary capillaritis presenting as diffuse alveolar hemorrhage is a rare manifestation in patients with IgA nephropathy. A 20-year-old male with hemodialysis dependent, end-stage renal failure presented with recurrent hemoptysis and respiratory failure. A histologic diagnosis of pulmonary capillaritis was established by transbronchial lung biopsy. He was successfully treated with intravenous methylprednisone and plasma exchange followed by oral prednisone and cyclophosphamide. This report highlights the independent renal and pulmonary manifestations of IgA nephropathy and the management of the resultant diffuse alveolar hemorrhage with aggressive immunosuppression.

Clinical use of high-frequency oscillatory ventilation in adult patients with acute respiratory distress syndrome.

OBJECTIVE: High-frequency oscillatory ventilation (HFOV) is an emerging ventilatory strategy for adults that has been used successfully in the neonatal and pediatric population. This modality utilizes high mean airway pressures to maintain an open lung and low tidal volumes at a high frequency that allow for adequate ventilation while at the same time preventing alveolar overdistension. With the current understanding that excessive lung stretch and inadequate end-expiratory ventilatory volume may be injurious to the lungs, HFOV seems to be the ideal lung-protective ventilatory mode. During the past 8 yrs, there have been increasing numbers of studies describing its use in adult patients with acute respiratory distress syndrome. This article aims to review the published studies of HFOV in adults with acute respiratory distress syndrome with regard to its safety and efficacy. DATA SOURCE: To assist us with our review, we did a search of MEDLINE (from 1966 to present) and EMBASE (1980 to present) databases to identify adult, clinical, English-language, research articles related to HFOV use. In addition, we reviewed relevant animal and mechanical ventilation studies. We did not perform a formal systematic review. DATA SYNTHESIS: The application of HFOV was mainly reported as a rescue ventilatory mode in adult patients with acute respiratory distress syndrome who were thought to have failed conventional ventilation. In these patients, HFOV has consistently been shown to improve oxygenation without obvious increases in complications measured. There was only one randomized, controlled trial comparing HFOV with conventional ventilation. This study showed that there was a nonsignificant trend toward a lower mortality rate in the HFOV group. In addition, HFOV was as effective and safe as conventional ventilation. Although there are limitations, multiple studies have shown that earlier initiation of HFOV in patients with severe acute respiratory distress syndrome may also be associated with a lower mortality. CONCLUSIONS: HFOV seems to be safe and effective for adults with severe acute respiratory distress syndrome who have failed conventional ventilation. Further research is needed to determine the ideal patients, timing, and optimal technique with which to provide HFOV. When considering HFOV as an early, lung-protective mode of ventilation, there is still a need to perform an adequately powered, randomized, controlled trial comparing it with the best available form of conventional ventilation. However, we believe that such a trial should wait until we have a better understanding of HFOV in adults.