Incidence of colonization, nosocomial pneumonia, and mortality in critically ill patients using a Trach Care closed-suction system versus an open-suction system: prospective, randomized study.

Eighty-four intubated, mechanically ventilated patients were prospectively evaluated for incidences of colonization and nosocomial pneumonias dependent on whether they received endotracheal suctioning by an "open" suction method vs. "closed" suction (Trach Care Closed Suction System) method. Results show that closed suctioning is associated with a significant (67% vs. 39% p less than .02) increase in colonization compared with open suctioning. However, difference in the incidence of nosocomial pneumonia was not significantly (26% vs. 29%) different between closed and open suctioning. Differences in severity of illness (Acute Physiology and Chronic Health Evaluation II and Therapeutic Intervention Scoring System), age, sex, presence of NG tubes, use of H2 antagonists or antacids, use of antibiotics, and history of smoking were all nonsignificant. Survival analysis demonstrated that the probability of survival without developing nosocomial pneumonia was greater among closed-suctioning patients vs. open-suctioned patients (p less than .03). This study shows that suctioning performed via the Trach Care closed-suction system increases the incidence of colonization but not the incidence of nosocomial pneumonia, and may actually decrease mortality when compared with open-suction systems.

Isolation of human platelet membrane microparticles from plasma and serum.

Methods have been developed to isolate human platelet membrane fragments from plasma and serum. Rabbit antibody produced against the human platelet membrane glycoprotein complex, IIb/IIIa, was utilized in an immunoelectrophoretic assay to evaluate the amount of this antigen in various microparticle preparations. The serum concentration of platelet microparticles was more than tenfold greater than that observed for plasma (65 micrograms/ml versus 4.4 micrograms/ml, respectively). Ultrastructural evaluation of either plasma or serum-derived microparticles disclosed a variety of membrane fragments and membrane-bound vesicles with occasional fragments of red blood cells, white blood cells, and platelets. In contrast, microparticle preparations derived from isolated washed platelets after thrombin stimulation contained a heterogeneous array of membrane fragments, vesicles, and granules but no identifiable red cell, white cell, or platelet fragments. Thus, these studies demonstrate that normal human plasma and serum contain platelet membrane fragments that are produced during cell activation. If a similar loss of platelet membranes occurs in vivo following reversible platelet activation, it is possible that the resulting membrane modifications may be of importance in both the structural and functional changes that develop during platelet senescence.

Human polymorphonuclear leukocyte phagocytosis in pregnancy. Development of inhibition during gestation and recovery in the postpartum period.

The phagocytosis of S. aureus by normal human PMN leukocytes was inhibited by pregnancy serum. Control sera from normal adult nulliparous women, from men, and from cord blood all functioned normally in support of phagocytosis. However, particle ingestion was reduced significantly (p less than 0.001) when leukocytes were in 15% pregnancy serum obtained at term. To determine at what stage in pregnancy the inhibition of phagocytosis could first be detected, sera were obtained from multiple pregnant donors and pooled according to week of gestation. Significantly fewer bacteria were ingested in each of the serum pools obtained after week 16 of pregnancy and the inhibitory effect persisted through gestation. Following delivery, less inhibition was detected as early as 2 days post partum. Phagocytosis assays were performed in six matched maternal and cord serum pairs. Five of the six maternal sera showed inhibition of phagocytosis; one pregnancy and all cord sera functioned normally in support of bacterial ingestion by normal granulocytes. Since neutrophils are essential to the development of rheumatoid arthritis and certian other inflammatory disorders, the subsidence of these diseases during gestation and their exacerbation post partum could be related, at least in part, to the inhibitory effects of pregnancy serum on leukocyte functions.