New strategies for mechanical ventilation. Lung protective ventilation.

Although research is ongoing, and there are no definitive data to mandate the final answer to the question of which ventilation strategies result in the most optimal outcomes, the consensus of clinicians today suggests that we limit FIO2 to nontoxic levels, limit ventilating pressures and volumes, and use PEEP levels adequate to recruit alveoli and prevent tidal collapse. The critical care nurse must remain vigilant in his or her review of current literature to maintain knowledge of the current recommendations for optimal MV strategies.

Are frequent inner cannula changes necessary?: A pilot study.

OBJECTIVE: To determine the incidence of obstruction and colonization in adult patients in the surgical and medical intensive care units who received inner cannula changes daily versus those who did not. DESIGN: Quasi-experimental prospective study using a convenience sample of patients randomly assigned to one of two methods. SETTING: Mid-Atlantic university-affiliated tertiary care center. PATIENTS: Sixty patients within 24 hours of receiving a surgical tracheostomy. OUTCOME MEASURES: Obstruction and bacterial colonization of inner cannula. INTERVENTIONS: All inner cannulas were checked daily for obstruction and cultured on postoperative days 1 and 3. RESULTS: No statistically significant difference was noted in colonization (p = 0.13) between protocols, and no obstructions were noted in either. CONCLUSION: The study suggests that the routine practice in critical care units of changing tracheostomy inner cannulas may be unnecessary. Although the results of this study are limited, and may not be generalized to other populations, it demonstrates that practice standards related to the care of tracheostomy inner cannula need to be challenged.

Design, testing, and results of an outcomes-managed approach to patients requiring prolonged mechanical ventilation.

BACKGROUND: Outcomes management that uses critical pathways may decrease costs while improving outcomes for patients who require prolonged mechanical ventilation. OBJECTIVE: To study the efficacy of an outcomes-managed approach to weaning patients from prolonged (more than 3 days) mechanical ventilation. METHODS: A method of multidisciplinary care delivery was designed that included an outcomes manager, a care pathway for patients receiving mechanical ventilation, and weaning protocols. Data collection consisted of three parts: a retrospective review of 124 patients who required prolonged ventilation during a 1-year period before implementation of the care model, a 6-month prospective study in which 91 patients were alternately assigned by month to an outcomes-managed approach or a non-outcomes-managed approach, and a 6-month prospective study of 90 patients in which an outcomes-managed approach without alternate-month assignment was used. RESULTS: Outcomes management had no significant effect on total duration of mechanical ventilation or length of stay in the hospital, days of mechanical ventilation without tracheostomy, days of mechanical ventilation with tracheostomy, or outcome (weaned, withdrawal from mechanical ventilation, death, or transfer without weaning). However, duration of mechanical ventilation was 1.3 days shorter, length of stay in the hospital was 2.1 days shorter, and the cost per case was $ 3341 less for patients in the outcomes-managed group than for patients in the non-outcomes-managed group. CONCLUSION: Outcomes-managed care did not have a significant effect on duration of ventilation, length of stay in the hospital, or outcome in patients receiving long-term mechanical ventilation.

Preventing complications of mechanical ventilation: permissive hypercapnia.

Research suggests that the forces exerted on the lungs by mechanical ventilators may cause as much damage to the lungs as the original pathologic process. In an attempt to limit additional injury to damaged lungs and improve the morbidity and mortality of patients requiring mechanical ventilation, investigators have proposed a controversial method of ventilatory management, permissive hypercapnia. This method attempts to maintain adequate oxygenation while allowing ventilation to decrease; carbon dioxide increases. The use of permissive hypercapnia is advocated in patients with acute lung injury and status asthmaticus. Ventilating pressures and volumes are lowered, with a resultant lower minute ventilation. Few adverse effects have been noted when this process has occurred gradually. By using permissive hypercapnia from the initiation of mechanical ventilation, it is possible to support the body through the resolution of the disease process while preventing additional lung injury.

Prenatal diagnosis of tetrasomy 47,XY,+i(12p) confirmed by in situ hybridization.

A case of tetrasomy i(12p) detected prenatally is reported. The patient, a black, 32-year-old G3P2002 at 24 weeks' gestation with an unremarkable family history presented herself for prenatal care. Ultrasound examination showed a fetus with diminished femoral and humeral lengths, and hydramnios. A level II scan confirmed the presence of an omphalocele. Amniocentesis at 31 weeks showed 47,XY,+i(12p) karyotype. An infant with multiple congenital anomalies was delivered at 34 weeks. The infant died after 5 h. Genetic and ultrasonographic examinations in the third trimester were helpful in the investigation of this fetus with multiple congenital anomalies. The careful, complete team counselling afforded by this approach enabled the mother and family to be well adjusted to the strong possibility (and subsequent reality) of an abnormal infant.

Long survival in a 69,XXY triploid male.

We report on an infant with a 69,XXY chromosome constitution who survived for 10 1/2 months; this is the longest survival reported with this condition to date. The infrequency of this disorder, data on natural history, and improved survival, possibly due to better management of respiratory illness and prematurity, are all factors worth noting in counseling on such rare conditions. Genotyping demonstrated the extra genome to be of maternal origin.

Preleukemia and leukemia with 12p- and 19q+ chromosome alterations following Alkeran therapy.

Among 20 patients with acute nonlymphocytic leukemia or dysmyelopoietic preleukemia secondary to Alkeran therapy for another tumor, four had a del(12)(p11-p12) and four had a translocation to 19q13 among multiple karyotypic alterations in their neoplastic hematopoetic clones. It is suggested that these two cytogenetic abnormalities may occur nonrandomly in such hemic disorders and may play a limited role in their pathogenesis.

Progressive preleukemia with a chromosomally abnormal clone in a kindred with the Estren-Dameshek variant of Fanconi's anemia.

One of two sisters with hypoplastic anemia and increased chromosomal fragility, but no clinical stigmata of Fanconi's anemia (FA), progressed to preleukemia (with a clone of chromosomally abnormal cells in the bone marrow), and then to acute nonlymphocytic leukemia. The findings indicate that constitutional genetic instability can lead to karyotypically aberrant neoplastic clones in the Estren-Dameshek variant of FA as well as in the more typical chromosomal fragility syndromes.

Ph1-positive acute leukemia with a 17q;21q translocation.

Chromosome studies on the neoplastic cells of an adult patient with poorly differentiated acute leukemia revealed two Ph1-positive subpopulations, with and without a 17q;21q (q22;q22) translocation. The breakpoints appeared to be the same as in the 8;21 and 15;17 translocations of acute mytelogenous leukemia (AML) and acute promyelocytic leukemia (APL), emphasizing the significance of rearrangements involving these sites in the pathogenesis of acute leukemia. Terminally, there was clonal evolution, with the new predominant subline having an additional translocation, 1q;19q, resulting in trisomy for most of 1q and, apparently, additional selective advantage.

Cytogenetics of childhood preleukemia.

Chromosome studies were done on ten children with childhood preleukemia characterized by anemia, thrombocytopenia, blasts in the circulation, and hypercellular marrow with excess blasts. The syndrome was clinically similar to adult preleukemia (myelodysplastic disorder). A chromosomally abnormal clone was found in the marrow in five patients: three with monosomy 7; one with a chromosome No. 21 replaced by two isochromosomes for 21q; and one with multiple alterations including an extra, abnormal chromosome No. 7. It was not apparent that a karyotypic change indicated a worse prognosis. The observed chromosome abnormalities appeared to overlap less with those in acute nonlymphocytic leukemia occurring de novo than is the case in adults, perhaps reflecting differing contributions of genetic and environmental factors to the pathogenesis of the disease at different ages.