Influence of airway management on ventilator-associated pneumonia: evidence from randomized trials

OBJECTIVE: Ventilator-associated pneumonia (VAP) is a serious complication of critical illness, conferring increased morbidity and mortality. Many interventions have been studied to reduce the risk of VAP. We systematically reviewed the influence of airway management on VAP in critically ill patients. DATA SOURCES: Studies were identified through searching MEDLINE and EMBASE from 1980 through July 1997 and by searching SCISEARCH, the Cochrane Library, bibliographies of primary and review articles, personal files, and contact with authors of the randomized trials. STUDY SELECTION: We selected randomized trials evaluating ventilator circuit and secretion management strategies on the rate of VAP. DATA EXTRACTION: Two investigators independently abstracted key data on design features, the population, intervention, and outcome of the studies. DATA SYNTHESIS: The frequency of ventilator circuit changes and the type of endotracheal suction system do not appear to influence VAP rates (3 trials, none with significant difference; range of relative risks [RRs], 0.84-0.91). However, lower VAP rates may be associated with avoidance of heated humidifiers and use of heat and moisture exchangers (5 trials, only 1 showing a significant difference; range of RRs, 0.34-0.86), use of oral vs nasal intubation (1 trial; RR, 0.52; 95% confidence interval, 0.24-1.13), subglottic secretion drainage vs standard endotracheal tubes (2 trials, 1 showing a significant difference; range of RRs, 0.46-0.57), and kinetic vs conventional beds (5 trials, only 1 showing a significant difference; range of RRs, 0.35-0.78). CONCLUSIONS: Some ventilator circuit and secretion management strategies may influence VAP rates in critically ill patients. Whether these strategies are adopted in practice depends on several factors such as the magnitude and precision of estimates of benefit and harm, as well as access, availability, and costs.     

The use of fine needle aspiration biopsy in the management of thyroid disease

Fine needle aspiration biopsy is now a first line investigation in thyroid disease. The purpose of this study was to evaluate the results of this technique in comparison with routine histopathology. A total of 593 aspirations over a four year period were included. There were 390 (65.7%) solitary nodules, 124 (20.9%) multinodular goiters, 66 (11.1%) diffuse goitres and 13 (2.2%) recurrent post thyroidectomy nodules. Radioisotope scanning in 386 cases showed 325 (84.2%) cold nodules, 54 (14.0%) warm nodules and 7 (1.8%) hot nodules. There were 458 (77.2%) colloid goitres and cysts, 14 cases of thyroiditis (2.2%) and 30 malignancies diagnosed on fine needle aspiration biopsy. In 19 cases (3.2%) a diagnosis of follicular neoplasm and in 29 cases (4.9%) a diagnosis of suspicious aspirate was made. Histological results were available in 176 cases. In 108 cases findings of histology and FNAB were compared with radioisotope scanning. A sensitivity of 92.8% and 42.8%, a specificity of 90.1% and 98.7% and accuracy index of 90.3% and 94.3% was found, when considering suspicious cases alternatively as positives and negatives. Surgery was recommended in all suspicious cases to prevent reduction in sensitivity of the technique. Fine needle aspiration biopsy was found to be a highly effective procedure which can obviate a lot of unnecessary surgery in thyroid lesions.     

Small airway closure and positive end-expiratory pressure in mechanically ventilated patients with chronic obstructive pulmonary disease

The effects of positive end-expiratory pressure (PEEP) on alveolar recruitment and closing volume were studied in ten supine, sedated, and paralyzed patients with chronic obstructive respiratory disease and acute respiratory failure. We applied PEEP (0, 5, 10, and 15 cm H2O) and constructed inflation static volume-pressure (V-P) curves. In all patients, the static V-P curves obtained at different PEEP levels were superimposed on each other, indicating that with PEEP there was no recruitment of previously atelectatic lung units. However, the static V-P curves exhibited an inflection point, which should reflect the critical pressure (Po) required to reopen all closed airways, whilst the corresponding lung volume (Vo) reflects the opening volume. On average, Vo was 0.71 L above the relaxation volume of the respiratory system (Vr). All patients, however, exhibited dynamic hyperinflation, i.e., with zero PEEP (ZEEP) the end-expiratory lung volume (EELV) was 0.54 L above Vr. Nevertheless, in seven patients the EELV on ZEEP was below Vo, resulting in cyclic reopening and closure of small airways with each breathing cycle, with concomitant mechanical stresses on the peripheral airways that may lead to low-volume barotrauma. Such barotrauma may be prevented by increasing with PEEP the EELV to Vo.     

Decrease in costs for management of lower airway disease in the pediatric intensive care unit

PURPOSE: Hypertensive patients exhibit exaggerated cardiovascular responses to tracheal extubation. This study was undertaken to examine the inhibitory effects of calcium channel blockers, nicardipine and diltiazem, on haemodynamic changes after tracheal extubation. METHODS: Sixty hypertensive patients (ASA physical status II) undergoing elective orthopaedic (upper and lower extremity) surgery received, in a randomized, double-blind manner, 30 micrograms.kg-1 nicardipine, 0.2 mg.kg-1 diltiazem or saline (as a control) (n = 20 of each) i.v. before tracheal extubation. Changes in heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before and after tracheal extubation. RESULTS: The HR, MAP and RPP increased after tracheal extubation in the control group (P < 0.05). The increases in these haemodynamic variables were attenuated with nicardipine or diltiazem. The inhibitory effects of diltiazem on these cardiovascular responses to tracheal extubation were greater than those of nicardipine (HR; 86 +/- 7 vs 101 +/- 10, RPP; 11,437 +/- 1,575 vs 14,675 +/- 2,874, mean +/- SD, P < 0.05). CONCLUSION: Compared with nicardipine, administration of diltiazem produced greater attenuating the circulatory responses to tracheal extubation in hypertensive patients.     

慢性阻塞性肺疾病患者气道过敏毒素C3a的变化

目的:研究补体裂解产物过敏毒素(C3a)在慢性阻塞性肺疾病(chronic obstruct1ve pulmonary disease,COPD)发病中的作用.方法:纳入COPD患者64例,其中男性51例、女性13例,COPD急性加重期患者组31例、稳定期患者组33例;另有健康对照25例.在入选时收集受试者的一般情况、测定肺功能、将诱导痰离心后留取痰液上清液测定C3a,对细胞沉渣进行炎症细胞分类计数.结果:COPD急性加重期组的诱导痰中C3a水平较COPD稳定期组及对照组升高,分别为44.2(13.2～48.5)μg/L、5.5(3.6～20.7)μg/L、1.7(0.1～5.9)μg/L,组间差异有统计学意义(Z=-2.974、-3.145,P=0.003、0.002).COPD稳定期组的诱导痰中C3a水平较对照组升高,但两组间差异无统计学意义(P＞0.017).健康对照组中的吸烟者与非吸烟者的诱导痰中C3a水平分别为1.97(0.12～6.27)μg/L、1.36(0.09～5.57)μg/L,两者差异无统计学意义(P＞0.05).COPD急性加重期患者组的诱导痰中C3a水平与炎症细胞总数呈正相关(r=0.543,P＜0.05).结论:C3a在COPD患者诱导痰中的水平增高,且与疾病的严重程度相关,提示其在疾病发生、发展中可能存在重要的作用.     

The hypoxaemia in chronic obstructive pulmonary disease (COPD) and its management

Three cDNAs that encode two-component phosphorelay-mediator-like proteins were cloned from Arabidopsis thaliana. Putative proteins (ATHP1-3) contain an HPt (Histidine-containing Phospho transfer)-like domain with a conserved histidine and some invariant residues that are involved in phosphorelay. Growth retardation of YPD1-disrupted yeast cells was reversed with ATHPs, which indicates that ATHPs function as phosphorelay mediators in yeast cells. The ATHP genes are expressed more in roots than in other tissues, similar to the expression of genes for a sensor histidine kinase, ATHK1, and response regulators ATRR1-4. These results suggest that ATHPs function as two-component phosphorelay mediators between sensor histidine kinase and response regulators in Arabidopsis.     

Vietnam: appropriate management of a pediatric hospital in the context of limited resources

The presence of any pulsatile mass suggests an underlying aneurysm. When such masses occur in the buttock, the differential diagnosis includes aneurysms arising from branches of gluteal vessels or aneurysms developing in a persistent sciatic artery (PSA). The investigation and management of two patients with pulsatile masses are described. Review of the embryologic aspects of these masses and the important literature on the subject led to the conclusions that when a pulsatile buttock mass is encountered, an anomalous PSA should be suspected. A gluteal artery aneurysm can be treated by ligation or occlusion, but for a sciatic artery aneurysm surgical ablation is necessary and distal perfusion must be achieved postoperatively.     

Pediatric thyroid nodules: management in the era of fine needle aspiration

BACKGROUND/PURPOSE: Thyroid nodules are rare in children. The need to uncover malignancy is the most challenging dilemma in management. The aim of this report was to determine whether management of pediatric thyroid nodules has changed in the era of fine-needle aspiration (FNA) cytology. METHODS: Twenty-four children with thyroid nodules comprised the study group. Demographic characteristics, clinical manifestations, imaging results, FNA cytology results, surgical therapy, complications, and pathological reports were reviewed retrospectively. FNA cytology results were categorized as either benign, malignant, suspicious, or insufficient. RESULTS: Girls outnumbered boys (five to one) with a mean age of 14.9 years. Nineteen nodules were benign and five malignant. Malignancy was characterized by localized tenderness, multiglandular appearance, and fixation to adjacent tissues. Ultrasound scans and nuclear scans gave no clue toward management because cystic, hot, and warm nodules figured among malignant cases. FNA in 18 children achieved 80% accuracy, 60% sensitivity, 90% specificity, 75% positive, and 81% negative predictive value. Physical examination findings, persistence of the nodule, and progressive growth decided for surgery in most children. CONCLUSIONS: FNA is a safe adjunctive test that plays a minor role in the decision to withhold surgery. Its greatest strength is to resolve, in case of suspicious or malignant cytology, that a more radical procedure will be needed. Clinical judgement as determined by serial physical findings continues to be the most important factor in the management of thyroid nodules in children.     

Effect of blood gas derangement on QTc dispersion in severe chronic obstructive pulmonary disease: evidence of an electropathy?

Mature myocardium utilizes calcium released by the sarcoplasmic reticulum (SR) for cell contraction. Transient exposure of mature myocytes to caffeine is known to directly trigger Ca2+ release from the SR. In contrast, neonatal rabbit heart cells rely on transsarcolemmal Ca2+ influx for tension generation. SR function is decreased in immature heart and appears to play a minimal role as a calcium source. Accordingly, we hypothesized that neonatal rabbit myocytes would not respond to a caffeine pulse. Isolated neonatal and adult myocytes were paced to load the SR with calcium and then exposed to a 1-s pulse of 10 mM caffeine. As previously described, adult myocytes exhibited a brisk contraction in response to caffeine. Unexpectedly, neonatal myocytes also exhibited a similar, brisk response. These caffeine-induced contractions were not dependent on extracellular Ca2+ but were dependent upon the loading of SR Ca2+ stores. When SR Ca2+ stores were depleted by exposure to caffeine, mature myocytes exhibited only small, slow contractions in response to electrical field stimulation. Replenishing the SR Ca2+ stores resulted in normal, brisk contractions. In contrast, electrically stimulated contractions in immature myocytes were largely unaffected by caffeine-induced SR depletion. Thus, although neonatal myocytes are capable of loading and releasing calcium from the SR, such SR calcium release is not normally required for contraction in the developing heart. The minor role of SR Ca2+ release in immature rabbit heart may not result from immaturity of the SR, but rather from an inadequate mechanism to trigger SR calcium release.     

Undetectable maternal serum unconjugated estriol levels in the second trimester: risk of perinatal complications associated with placental sulfatase deficiency

OBJECTIVE: Our purpose was to determine the prevalence of undetectably low second-trimester maternal serum unconjugated estriol levels and the association with increased perinatal morbidity or mortality in pregnancies at risk for placental sulfatase deficiency. STUDY DESIGN: Nine centers in New England identified singleton pregnancies with undetectably low unconjugated estriol levels. Each unexplained case was matched with four controls; pregnancy outcome information was sought. RESULTS: Among 130,295 pregnancies surveyed, undetectably low unconjugated estriol levels were identified in 167 (13/10,000). Explanations included fetal death (53), overestimated gestational age (50), nonpregnancy (12), and chromosome abnormalities (5). The 41 unexplained cases were compared with 163 matched controls. Male offspring were more frequent (85%) among cases than among controls (55%). Although rates of perinatal complications were not significantly different, primary cesarean sections occurred about twice as often among cases. No perinatal deaths occurred. CONCLUSIONS: Neither severity of symptoms nor perinatal morbidity or mortality currently warrant routine interpretation of unexplained undetectably low unconjugated estriol levels as a marker for placental sulfatase deficiency.     

Neutrophil serine proteinases and defensins in chronic obstructive pulmonary disease: effects on pulmonary epithelium

Neutrophils have the capacity to accumulate in high numbers in the lung during infection and inflammation. Because they play an important role in host defence against infection, but may also cause tissue injury, these cells are thought to be involved in the pathogenesis of various inflammatory lung disorders, including chronic bronchitis and chronic obstructive pulmonary disease. Neutrophil products that may mediate tissue injury at sites of neutrophil-dominated inflammation include the neutrophil serine proteinases elastase, cathepsin G and proteinase 3, and the nonenzymatic defensins. One of the targets of the neutrophil is the lung epithelium, and in vitro studies have revealed that both the serine proteinases and neutrophil defensins markedly affect the integrity of the epithelial layer, decrease the frequency of ciliary beat, increase the secretion of mucus, and induce the synthesis of epithelium-derived mediators that may influence the amplification and resolution of neutrophil-dominated inflammation. Both neutrophil elastase and defensins induce the release of the neutrophil chemoattractant chemokine interleukin-8 from respiratory epithelial cells. The alpha1-proteinase inhibitor (alpha1-PI) is a well-characterized inhibitor of neutrophil elastase, that also blocks the cytotoxic and stimulatory activity of defensins towards epithelial cells. The elastase inhibitory activity of alpha1-PI is also abrogated by the binding of defensins to this inhibitor. Incubation of epithelial cells with neutrophil defensins in combination with either elastase or cathepsin G resulted in decreased effects on the epithelial cells compared with those observed when the cells were incubated with defensins, elastase or cathepsin G separately. These results suggest that neutrophil defensins and serine proteinases cause injury and stimulate epithelial cells to produce chemokines that attract more neutrophils to the site of inflammation. The effects of neutrophil defensins and serine proteinases on epithelial cells appear to be restricted by proteinase inhibitors and by inhibitory interactions between these sets of neutrophil granule proteins.     

Hyperkalemia in end-stage renal disease: mechanisms and management

Clinical investigations in the past few years have enhanced the understanding of the mechanisms of hyperkalemia in patients with ESRD. The results of these studies have led to modifications in the acute treatment and prevention of hyperkalemia in this patient population. They have confirmed the efficacy of intravenous insulin, while raising doubts about the utility of intravenous bicarbonate, for the acute treatment of hyperkalemia. Moreover, the beta-adrenergic agonist albuterol has been shown to be a useful adjunct to insulin for acutely lowering plasma potassium. Finally, there has been enhanced recognition of nondietary factors that can predispose to hyperkalemia in patients with ESRD, including prolonged fasting and the use of nonselective beta-adrenergic blockers. These new insights may improve the clinical management of hyperkalemia in patients with renal failure.     

Hyperthyroidism: diagnosis and management of Graves' disease

Hyperthyroidism, or thyrotoxicosis, results when the body's tissues are exposed to excessive levels of thyroid hormone. Hyperthyroidism affects 2% of women but only one-tenth as many men. Graves' disease is the most common form of hyperthyroidism, often occurring in young adults. It is an autoimmune disorder with an important genetic component. Hyperthyroidism's hallmarks include goiter and myriad signs and symptoms related to increased metabolic activity in virtually all body tissues. Increased sensitivity to circulating catecholamines adds to the clinical picture. Diagnosed by patient history, physical examination, and laboratory tests, Graves' disease is treated with antithyroid drugs, radioactive iodine, and/or surgery, plus supportive therapy. A good treatment outcome can be expected; long-term follow-up is indicated.