Acute Respiratory Failure

Acute respiratory failure in critically ill patients with cancer. Diagnosis and management

Respiratory failure remains a common cause of admission to the ICU for patients with cancer, regardless of the nature of malignancy. The diagnosis and management of ARF in patients with cancer poses special challenges to the intensivist. Depending on the type of cancer, the degree of immunosuppression, underlying comorbidities, the modality of cancer treatment, progression or spread of underlying cancer, and disease- or therapy-associated complications are the most common causes of ARF in these patients. Despite significant advances in antineoplastic therapies and supportive management in the ICU, the mortality rate of patients with cancer with ARF remains high. Severity-of-illness scoring systems and mortality probability models, although useful in discriminating between survivors and nonsurvivors in large groups of critically ill patients, should not be used alone to justify reluctance in admitting individual patients with cancer with potentially reversible respiratory failure to the ICU. Close collaboration between oncologists and intensivists will ensure the establishment of clear goals and direction of treatment for every patient with cancer who requires mechanical ventilation.

Bacteremia due to viridans streptococci in neutropenic patients: a review

Viridans streptococci have long been considered, with the exception of the ability to cause endocarditis, as minor pathogenic agents. More recently, however, these bacteria have become a major concern in neutropenic patients undergoing a chemotherapeutic treatment. In this high-risk population, they can be responsible for up to 39% of bacteremia cases and are the most frequent cause of this type of infection. The most frequently isolated species in blood cultures are Streptococcus mitis and Streptococcus sanguis II. Viridans streptococcus bacteremia can be accompanied by serious complications, like adult respiratory distress syndrome (ARDS) (3% to 33%), shock (7% to 18%) or endocarditis (7% to 8%). Mortality rates range from 6% to 30%. Case-control studies have identified the following risk factors: severe neutropenia (< 100 neutrophils/mm3), prophylactic antibiotic treatments with quinolone or co-trimoxazole, absence of intravenous antibiotics at the time of bacteremia, high doses of cytosine arabinoside, oropharyngeal mucositis, and heavy colonization by viridans streptococci. The introduction of penicillin in prophylactic antibiotic treatments has reduced the incidence of these infections, but the long-term use of penicillin could be compromised by the emergence of resistant strains.

Adult respiratory distress syndrome in severely neutropenic children

It has been suggested that polymorphonuclear cells (PMNs) are required for the development of the adult respiratory distress syndrome (ARDS). We investigated the occurrence of ARDS with acute respiratory failure in 30 children with severe neutropenia (less than 500 PMNs/mm3) who met the clinical diagnostic criteria for ARDS and in whom postmortem histopathology findings were available within 7 days of the onset of ARDS. In 26 patients the histopathology was consistent with ARDS. In 12/26 children no white blood cells (WBC) were found in the lung tissue, 10/26 had moderate infiltration of mononuclear cells, 2/26 had massive tumor cell infiltration, and in 2/26 PMNs were found. Thus, in at least 22/26 patients ARDS developed without neutrophilic infiltration of the lungs. The maximum active lung infection rate was found to be 69% (18/26) by endotracheal and post mortem lung cultures and histology. Thus 5/26 children had ARDS without any WBC in the lung tissue. We conclude, as have other studies in adults that the absence of PMNs does not protect children from the development of ARDS and that the mechanism which involves PMNs is probably only one of several pathways for diffuse alveolar damage, some of which is neutrophil-independent.